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Über dieses Buch

The Light Metals symposia at the TMS Annual Meeting & Exhibition present the most recent developments, discoveries, and practices in primary aluminum science and technology. The annual Light Metals volume has become the definitive reference in the field of aluminum production and related light metal technologies. The 2020 collection includes papers from the following symposia: • Alumina and Bauxite• Aluminum Alloys, Processing and Characterization• Aluminum Reduction Technology• Cast Shop Technology• Cast Shop Technology: Recycling and Sustainability Joint Session• Electrode Technology for Aluminum Production


Inhaltsverzeichnis

Frontmatter

Alumina and Bauxite

Frontmatter

Impacts of Mineralogy on Soluble Phosphorus Concentrations During Low Temperature Processing of Jamaican Bauxites

Jamaica has about 7.1% of world bauxite reserves. Traditionally, local refineries process good-settling low phosphorusPhosphorus bauxites. As these ores become scarce, mining areas with poor-settling high phosphorusPhosphorus bauxites are being explored. In preparation for having to process these bauxites, this study sought to identify the main minerals that influence soluble phosphorusPhosphorus concentrations. Four correlations for predicting soluble phosphorusPhosphorus during low temperature digestion were applied to both the currently-mined and future bauxite resources. Soluble phosphorusPhosphorus concentrations were successfully predicted from total phosphorusPhosphorus in the bauxite. A simple mine-specific correlation that adjusts based on the calcium to phosphorusPhosphorus (CaO:P2O5) ratio in the bauxites was able to predict soluble phosphorusPhosphorus to within ±15% of measured values. The correlation was applicable even to ores with highly variable compositions. If the phosphorusPhosphorus impurity in the future bauxite is taken as crandalliteCrandallite , a correlation that over-predicts the measured soluble phosphorusPhosphorus by about 20–30% can be used to assess lime requirements for phosphorusPhosphorus control. CrandalliteCrandallite , calcite and silica were the main minerals that influence soluble phosphorusPhosphorus concentrations.

Michael D. Coley, Anthony M. Greenaway, Khadeen E. Henry-Herah

Effects of the Granular Properties of Bauxite Pisolithes on the Solid/Liquid Separation in Liquid Fluidized Beds of Classifiers

Bauxite pisolites found in the Cape York region of Australia are typically near-spherical particlesParticles . Ore extracted from the Andoom (Weipa) deposit is processed through a beneficiation plant to remove the finer fraction; these finer particlesParticles will otherwise lead to material handling problems. A key component of the beneficiation flowsheet is a fluidized bed classifier, where fine particlesParticles are removed via an overflow system. The objective of this project was to study and understand the solid/liquid separation phenomena taking place in the fluidized bed, especially determining the role of the granular properties in controlling the separation mechanisms. Laboratory-scale experiments, using a transparent tank and glass beads of controlled grain size in place of bauxite, allowed an accurate observation of the fluidized bed behavior. Computer modeling, using multi-phase flow, was used to perform numerical simulationsNumerical simulations of the experimental setup and establish the relative effects of the parameters that control the separation processes in the fluidized bed.

T. Grillot, G. Simard, R. Chesnaux, D. Boudeville, L. Perrachon

Mineralogical Assessment of the Solid Phase Obtained on Leaching of Brazilian Red Mud

The main residue generated during the Bayer Process is the red mud or bauxite residue. In 2015, the quantity of red mud stored around the world reached 4 billion tonnes. The composition of the red mud varies according to the bauxite used in the alumina extraction process. The main components of the residue are iron, aluminum, silicon and titanium. Besides that, the red mud is the major source of scandiumScandium, which is considered a critically important metal. Hydrometallurgical processing is the main route used for scandiumScandium extraction from red mud. However, the effect of acid reaction in the red mud is not studied in-depth. For this reason, the goal of this work is the mineral assessmentMineral assessment of the solid phase obtained on leaching of Brazilian red mud. Thermodynamic simulations were carried out using FactSage 7.2 software to predict which phases can be formed during the leaching. The software is not explored for hydrometallurgical reactions in the literature. The Brazilian sample was leached by sulfuric acid 20%. The solid/liquid ratio was 1/10 and samples were analyzed in different time reactions at 25 °C. Results showed that the mineral phases obtained were in agreement with the thermodynamic simulation calculated using FactSage software. Also, the software has demonstrated to be an important tool for leaching studies.

A. B. Botelho Junior, D. C. R. Espinosa, J. A. S. Tenório

Low-Quality Aluminum-Containing Raw Materials: Experience, Problems and Prospects

Aluminum containing materials—nephelinesNepheline, leucites, clays, and industry-related wastes are considered as raw materials to produce aluminaAlumina and coproducts as an alternative to bauxite. The current industrial processing of aluminosilicate raw materials by the sintering methodSintering method is characterized by high energy consumption, which ultimately affects its cost competitiveness in comparison with bauxite processing by the Bayer process. Variants of processing alumosilicate raw materialsAlumosilicate raw materials in the areas of increasing the complexity of its use, modification of technology to reduce payback period and energy consumption are given. Practical experience is considered and other options for obtaining aluminaAlumina from nonconventional raw materials are discussed. The presented options allow for significantly reducing the cost of obtained aluminaAlumina and expanding the scope of raw materials that can be considered for processing.

Vadim Lipin, Ekaterina Sofronova

Inhibition of Kaolinite Dissolution in Bayer Liquor Through Lithium Addition

With increasing reactive silica in bauxite, sodium hydroxide consumption increases due to the increased precipitation of desilication productsDesilication products in the Bayer process. In this study, we report on how the presence of lithiumLithium in Bayer liquor inhibits the dissolution of kaoliniteKaolinite. The inhibition was studied at a temperature of 90 °C with residence times up to 6 h, and with Li:Si molar ratios of 0, 0.1, 0.5 and 1. The inhibition effect is attributed to the localised precipitation of Li/Al LDHLi/Al LDH (LiAl2(OH)7·2H2O) or adsorption of Li+ on the kaoliniteKaolinite surface. This phenomenon enables a low temperature digestion process to be contemplated whereby gibbsite is selectively dissolved in the presence of kaoliniteKaolinite, potentially leading to significant savings in sodium hydroxide as well as a low-alkaline bauxite residue. Economic trade-offs between lithiumLithium addition rates and sodium hydroxide savings are discussed.

Horace Ogilvie, James Vaughan, Hong Peng

Ionic Effect of NaCl and KCl on the Flotation of Diaspore and Kaolinite Using Sodium Oleate as Collector

The major type of bauxite in China is low-grade diasporic bauxite, which is mainly composed of diasporeDiaspore and kaoliniteKaolinite. Separation of silicate minerals by flotationFlotation technology can meet the requirements of Bayer process, but Na+, K+ and Cl− deriving from mineral dissolution and entrainment in flotationFlotation water will inevitably mix in the flotationFlotation slurry, which will affect the flotation of bauxite. The results of flotationFlotation show that NaClNaCl and KCl have little effect on the flotation of diasporeDiaspore, but NaCl has a beneficial effect on kaoliniteKaolinite flotation. It may be attributed to the ion size order Na+ < K+ < Cl−. Na+ has the ability to enter the layer spacing of kaoliniteKaolinite due to its smaller size, which increases the zeta potential and the dipole-dipole force between kaoliniteKaolinite and sodium oleate, therefore improving the flotationFlotation of kaoliniteKaolinite. In addition, Na+ has “salt effect” on the anionic collector, which also promotes the flotation of kaolinite. This study may have some reference significance to the industry flotation of diasporic bauxite.

Chaojun Fang, Shichao Yu, Hong Peng, Xiaowei Deng, Jun Wang

Quantifying the Effect of Seeds on Gibbsite Crystallization—Mathematical Modelling of Particle Size Distribution

A critical step in the Bayer processBayer Process is the crystallizationCrystallization of gibbsite (γ-Al(OH)3) from the caustic aluminate solution. It is necessary to add small gibbsite crystals as seeds in the crystallizationCrystallization circuit, which act as sites for the crystal growthCrystal growth and as material for agglomeration. Mathematical models are particularly useful in this context because they provide the particle evolution of the crystals as a function of time, together with the mass balances and reaction kinetics of crystallizationCrystallization . This work presents the particle size distributionParticle size distribution (PSD) modellingModelling of the Companhia Brasileira de Alumínio (CBA) aluminaAlumina refinery, developed in order to study seed effects, assisting the optimization and maximization of the process yield and aluminaAlumina quality.

Thiago T. Franco, Marcelo M. Seckler

Experimental Study on Flow Field Characteristics in Seed Precipitation Tank and Influence on Physical Properties of Al(OH)3 Products

Compared with the traditional air-mixing seed precipitation tank, the mechanical stirring seed precipitation tank has the characteristics of low energy consumption, less knot at the bottom of the tank, and uniform slurry mixing. In this paper, a new type of HSG/HQG combination impeller is used to study the liquid–solid two-phase mixing system in the mechanical stirring seed precipitation tank. The combination of PIVPIV software technology and experimental tank test is used to study the internal flow of the stirred tank. The properties of the field and various types of agitator are tested, and the physical properties of the seed decomposition products are tested under different impeller types and speeds. The results show that under the same physical parameters, using new HQG/HSG impeller structure, the crystal morphologyCrystal morphology of the seed products is better, the average particle sizeParticle size is more uniform, and the wear indexWear index and specific surface areaSpecific surface area are improved.

Xiangyu Zou, Yan Liu, Xiaolong Li, Ting’an Zhang

Application of Advanced Oxidative Process for Organic Compounds Removal from Bayer Liquor

One of the major problems in the aluminaAlumina industry is organics in Bayer liquorBayer liquor. It causes a decrease in aluminaAlumina quality and an increase in processing costs. It occurs due to the organic matter content present in bauxite. Among the technologies available to remove these organic compounds, the advanced oxidative processes (AOP) is one option. This technique consists of the degradation of recalcitrant compounds by the formation of radicals, such as the OH·. OzonationOzonation involves the injection of O3 for OH· generation. The process can be improved by adding H2O2, accelerating reaction kinetics. The aim of this work was to remove the organic compounds present in Bayer liquorBayer liquor through the injection of O3 and O3/H2O2 in a batch reactor. The effect of reagents’ concentration and temperature was evaluated. Results showed that increasing temperature raises the organic degradation in higher concentrations.

Miguel Antonio Soplin, Amilton Barbosa Botelho Junior, Marcela dos Passos Galluzzi Baltazar, Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa

A Review of Comprehensive Utilization of High-Iron Red Mud of China

With the increasing requirement of environmental protection, the treatment of red mudRed mud has become a more and more important issue. Depending on the various ironIron contents, red mudRed mud can be divided into low-ironIron red mudRed mud and high-ironIron red mudRed mud . This paper reviews the comprehensive utilizationComprehensive utilization of high-ironIron red mudRed mud of China. In particular, this paper reviews the methods for iron recoveryIron recovery from red mudRed mud : physical recoveryRecovery , hydrometallurgical recoveryRecovery and pyrometallurgical recoveryRecovery . This paper then introduces a new technique proposed by Northeastern University of China which can achieve high iron recoveryIron recovery and additional values from the molten slag. It is much preferred over the current methods. This method eliminates the pelletizing and sintering processes in blast furnace ironmaking shortening the technological process and saves energy greatly. The information should help to improve the future large-scale, high-value and zero wasteZero Waste utilizationUtilization of red mudRed mud .

Ting’an Zhang, Kun Wang, Yan Liu, Guozhi Lyu, Xiaofei Li, Xin Chen

Conversion Behavior of Iron-Containing Minerals in the Process of Dissolving High-Iron Bauxite by Starch Hydrothermal Method

The starchStarch is used as a reducing agent to simultaneously reduce the ironIron oxide during the hydrothermal dissolutionDissolution of the diasporeDiaspore . Thermodynamic calculation and experiments studied the hydrothermal reductionReduction behavior of ironIron oxide in alkaline solution, thermodynamic calculations show that Fe2O3 can be converted to Fe3O4 under appropriate redox conditions. Fe2O3 will dissolve in an alkaline aqueous solution to form FeO2−, and part of the FeO2− moiety will be converted to Fe(OH)4− in an alkaline aqueous solution having a temperature higher than 373 K. The starchStarch is degraded under alkaline hydrothermal conditions, releasing an aldehyde group to form a strong reductionReduction system, and reducing Fe3+ to Fe2+, and Fe3+ further reacts with Fe2+ to form Fe3O4. In this process, the temperature and alkali concentration in this process have a great influence on the hydrothermal reductionReduction of Fe2O3. The experimental results show that when the treatment temperature is 260 °C, the alkali concentration is 210 g/L, the time is 60 min, the lime/dry ore is 7%, the starchStarch /dry ore is 10%, and the magnetic separationMagnetic separation strength is 0.08 T. At this point, the aluminumAluminum dissolutionDissolution rate was 98.57%, the ironIron reductionReduction rate was 98.41%, the magnetic separationMagnetic separation rate was 97.0% or more, and the TFe grade was 73.5%.

Yongfei He, Yiyong Wang, Hun Jin, Ning Zhe, Xingyuan Wan

Disc Magnetic Separator Applied to the Extraction of Magnetite in Bauxite Residue

The valorizationValorization of bauxite residueBauxite Residue (BR) generated by the Bayer processBayer Process is a major challenge for the aluminaAlumina industry, for both economical and environmental reasons. Iron oxidesIron oxides , mainly goethite and hematiteHematite , are major constituents of bauxite residueBauxite Residue (BR) that also have a potential economic value. Many attempts have been reported in the literature, of reducing these species to magnetic iron oxidesIron oxides , such as magnetiteMagnetite , followed by its recoveryRecovery using magnetic separationMagnetic separation . No commercial success has however been reported to date. The initial steps of our detailed study, undertaken on the magnetic separationMagnetic separation process to extract the ironIron compounds from calcined bauxite residueBauxite Residue (BR) , have shown that a basic magnetic separator cannot recover the magnetiteMagnetite content. A homemade lab-scale disc magnetic separator has been fabricated and the influence of key parameters, such as solids concentration, feed flow rate, rotational speed, etc., was quantified. However, regardless of the equipment performance, the results are highly dependent on the material submitted to magnetic separationMagnetic separation . In order to properly evaluate the various parameters’ influence, and the efficiency of the separation process, an ideal mixture of magnetic material (magnetiteMagnetite ) and non-magnetic material (“as is” bauxite residueBauxite Residue (BR) ) was prepared and submitted to the disc magnetic separator. The collected material is enriched to more than 90 wt% magnetic content, from an initial 30 wt%.

Y. Robert, G. Simard, S. Fortin

Recovery of Iron from High-Iron Bayer Red Mud by Smelting Reduction

The high-iron Bayer red mudHigh-iron Bayer red mud , which contains 30–50% ironIron , is regarded as low-grade ironIron ore. With the global scarcity of ironIron supply worldwide, how to effectively utilize the ironIron in high-ironIron red mudRed mud has attracted more and more attention in recent decades. In this paper, the technology to recoveryRecovery of ironIron from high-ironIron red mudRed mud was developed with smelting reductionSmelting reduction followed by rapid cooling to separate the metal from slag. The effects of various experiment parameters such as temperature, basicity and reductionReduction time on iron recoveryIron recovery from red mudRed mud was studied in detail. The results showed that the separation between metal and slag was complete. The content of ironIron in metal and iron recoveryIron recovery ratio were 94.06 and 80.16% with basicity of 0.9 smelting at 1600 °C for 30 min. The optimum experiment result were of great significance to achieve large-scale, high-value utilizationUtilization of red mudRed mud .

Kun Wang, Yan Liu, Guozhi Lyu, Xiaofei Li, Xin Chen, Ting’an Zhang

Bayer Process Towards the Circular Economy—Metal Recovery from Bauxite Residue

On a global basis, 150 million tons of bauxite residueBauxite Residue (BR) (BR) are produced every year and the total inventory are estimated in 4.6 billion tons. BR still contains significant amounts of valuable metalsValuable metals such as Fe (6.8–71.9%), Ti (2.5–22.6%), Al (2.12–28.4%) and rare earth elements (REE) and can be considered a potential secondary source of raw materials. Its utilizationUtilization to recover these metals would follow the principles of the circular economy in mining sector and environmental impact mitigation. In 2017, Brazil produced 11 million tons of aluminaAlumina and around 8.8–16.5 million tons of BR. Here we evaluate the potential for wet direct magnetic iron recoveryIron recovery from a Brazilian BR using different magnetic field intensities. The BR had an ironIron concentration of 40.08% Fe2O3 where hematiteHematite was the main ironIron mineral phase. Particle size distributionParticle size distribution analysis and wet sieving assessment indicated a high concentration of finesFines (D90 < 43.7 μm), as well as, a narrow size distribution curve. The overall iron recoveryIron recovery was 11.5% w/w and the magnetic product achieved 59% Fe2O3. The data showed that all the coarser particles in the feed (8.34% w/w, < 100 μm) reported to the magnetic product while the finesFines were in the non-magnetic fraction, proving that particle sizeParticle size is fundamental for wet magnetic separationMagnetic separation of paramagnetic materials. Looking at the rough number, an ironIron magnetic recoveryRecovery rate of 11.5% could potentially recover around 0.3–0.6 million tons of ironIron annually.

Paula de Freitas Marques Araújo, Patricia Magalhães Pereira Silva, Andre Luiz Vilaça do Carmo, Fernando Gama Gomes, Alex Mota dos Santos, Raphael Vieira da Costa, Caio César Amorim de Melo, Adriano Reis Lucheta, Marcelo Montini

Bayer Process Towards the Circular Economy—Soil Conditioners from Bauxite Residue

Large-scale bauxite residueBauxite Residue (BR) (BR) reuse is still a challenge for aluminaAlumina producers worldwide. Agronomic applications for BR can be a sustainable and economically viable option for soil fertility improvement in countries where agriculture plays a crucial economic role, such as Brazil. This study reports a biological approach to partial BR alkalinity neutralizationNeutralization, allowing its safe application as a soil conditioner for fertility improvement in acidic tropical soils. Microcosm tests were established to assess the effect of incorporating local agro-industrial organic residues into the BR to generate acidity, while highly fertile undisturbed soil was added as a microbial inoculum. BR amendment with organic residues exhibited a fast pH neutralisation (from 10 to 6.5 at the second day of incubation). Results confirmed that the locally available organic residues and the soil added to BR improved its physical and chemical characteristics, allowing further research into its agronomic effects.

Roseanne Barata Holanda, Patricia Magalhães Pereira Silva, Andre Luiz Vilaça do Carmo, Alice Ferreira Cardoso, Raphael Vieira da Costa, Caio César Amorim de Melo, Adriano Reis Lucheta, Marcelo Montini

Brazilian Bauxite Residue Physical–Chemical Characterization and Acidic Neutralization Potential

Physical-chemical evaluation of Brazilian (Amazon region) bauxite residueBauxite Residue (BR) (BR) and analysis of its acid neutralizationNeutralization capacity (ANC) using, hydrochloric (HCl), sulfuric acid (H2SO4) and citric acid (C3H8O7) were carried out to assess the potential application of BR as soil ameliorant. Analysis indicated a particle sizeParticle size average size (D50) of 6.04 μm, 1.65 g cm−3 density and 18.28 mS cm−1 electrical conductivityElectrical conductivity. Mineral phases determined by XRD showed hematiteHematite, aluminous goethite, anatase, sodalite, gibbsite and quartz, in agreement with XRF (%) elemental characterization: Fe (24.38), Al (11.20), Si (7.91), Na (8.11), Ti (3.24), Ca (0.79), Zr (0.71), S (0.06), V (0.07) and Mn (0.09). ANC analyses conducted after 21 days indicated a lower acid consumption and pH equilibrium for H2SO4 and HCl (1.75 and 1.00 mol H+ kg−1, respectively and ~pH8) when comparing with C3H8O7 (2 mol H+ kg−1). Results validate and provide basis for an effective use of BR in agronomic applications.

Patricia Magalhães Pereira Silva, Andre Luiz Vilaça do Carmo, Roseanne Barata Holanda, Fernando Gama Gomes, Emanuele Nogueira, Raphael Vieira da Costa, Caio César Amorim de Melo, Adriano Reis Lucheta, Marcelo Montini

Effect of Concentrations and Pressures of CO2 on Calcification–Carbonation Treatment of Bauxite Residue

The calcification-carbonization process is attracting attention as a new, feasible method for clean production of aluminaAlumina and treatment of red mudRed mud. The carbonization stage within the overall process was investigated, and the effects of CO2 concentrationCO2 concentration and pressurePressure on the recoveryRecovery of sodium oxideSodium oxide and aluminaAlumina from red mudRed mud were studied in detail. The results showed that when the CO2 total pressurePressure is 1.2 MPa and the CO2 concentrationCO2 concentration is 99.99%, the recoveryRecovery of aluminaAlumina and sodium oxideSodium oxide reached 40.08% and 93.16%, respectively. Similar results can also be achieved when the CO2 partial pressurePressure is 1.2 MPa and the CO2 concentrationCO2 concentration is only 60%. And the main phase of solid slag is converted from hydrogarnet to CaCO3. This study aims to provide a theoretical basis for the industrialization of calcification-carbonization method.

Xi Chao, Ting-an Zhang, Guo-zhi Lv, Yang Chen

Comprehensive Utilization of Red Mud Through the Recovery of Valuable Metals and Reuse of the Residue

An integrated technological route for comprehensive utilizationComprehensive utilization of red mudRed mud through the extraction of valuable components and reuse of the magnetic residue is proposed. In this study, inductively coupled plasma atomic emission spectroscopy, X-ray fluorescence, X-ray powder diffraction, and vibrating sample magnetometer were used to characterize the process. The process includes sintering, alkaline leaching to recover Na and Al, and removal of lead ions from wastewater by magnetic residue containing magnesium ferriteMagnesium ferrite. The effects of various parameters were systematically investigated, and the optimal conditions were determined as: sintering temperature of 1150 °C and duration of 60 min, the mole ratio of CaO/SiO2 of 3, Na2O/Al2O3 of 1.2, and MgO/Fe2O3 of 1 in the raw material. Under the conditions, the results showed that approximately 74% Al and 95% Na were recovered from red mudRed mud by this route. The leach residue exhibits magnetic and adsorptionAdsorption properties, its adsorptionAdsorption capacity reaching about 70 mg/g at the initial Pb2+ concentration of 80 mg/L. Therefore, it may be a promising candidate in wastewater treatment and other fields.

Fei Lyu, Li Wang, Jiande Gao, Honghu Tang, Wei Sun, Yuehua Hu, Runqing Liu, Lei Sun

A Review of Research on Alumina Extraction from High-Alumina Fly Ash and a New Method for Preparing Alumina by Electrotransformation

When bauxite and aluminaAlumina resources are limited, high-alumina fly ashHigh-alumina fly ash becomes a potential aluminumAluminum resource. The comprehensive utilizationComprehensive utilization of high value-added elements in high-alumina fly ashHigh-alumina fly ash is of great significance to resource circulation. In order to solve the difficult comprehensive utilizationComprehensive utilization of valuable components in high-aluminaAlumina ash problem, the existing traditional research methods of high-aluminaAlumina ash are firstly summarized and compared in this paper. Following the review, a new method for the treatment of high-alumina fly ashHigh-alumina fly ash by electrotransformationElectrotransformation is proposed. This new method can realize reductionReduction in slag volumes, with no waste acid, no alkali input required. It can be concluded that this new method can effectively treat high-alumina fly ashHigh-alumina fly ash and realize the comprehensive utilizationComprehensive utilization of valuable components of high-alumina fly ashHigh-alumina fly ash .

Xiu-xiu Han, Ting-an Zhang, Guo-zhi Lv, Xi-juan Pan, Da-xue Fu

Effect of Sodium Alkali Concentration on Calcification–Carbonization Process

The calcification-carbonization method is a recently developed hydrometallurgical treatment process which can effectively realize the scale of Bayer process residueBayer process residue for aluminiumAluminium and sodium recoveryRecovery . In order to reduce the water consumption in the process, and increase extraction efficiency of the low alkali concentration solution generated in the process, the effects of varying alkali concentration of the calcification reaction solution and the alkali concentration of the carbonization reaction solution on the calcification carbonization process were investigated. The experimental results showed that at low alkali concentration (Na2O < 50 g/L), the solution had no significant effect on the calcification-carbonization process, as Al2O3 recovery rateAl2O3 recovery rate fluctuates between 34–37%. As the alkali concentration of the solution increases (Na2O > 50 g/L), the Al2O3 recovery rateAl2O3 recovery rate decreases to less than 20%.

Yang Chen, Ting-an Zhang, Guo-zhi Lv, Xi Chao

Aluminum Alloys, Processing and Characterization

Frontmatter

Stress Characterization of Bore-Chilled Sand Cast Aluminum Engine Blocks in As-Cast and T7 Condition with Application of Neutron Diffraction

In an effort to improve vehicle fuel efficiency, aluminumAluminum (Al) alloys have been gaining upward momentum for use in automotive powertrain components such as engine blocks. Al alloys are lightweight and have good mechanical strength at engine operating temperatures; making them a suitable choice for engine block production. However, during the manufacturing process factors such as inhomogeneous cooling ratesCooling rates and/or coefficients thermal expansion mismatches in multi-material castings can lead to the development of residual stress. This is of particular concern for the relatively thin cylinder bridges, which are exposed to large thermo-mechanical loading during engine operation. The castingCasting process used at Nemak for I6 engine block production does not utilise cast-in liners and therefore may be also be suitable for future mass-produced linerless blocks. This paper utilizes neutron diffractionNeutron diffraction and SEM/EDS to determine how the elimination of cast-in liners as well as a T7 heat treatment effects the magnitude of residual stress in cast Al (A319 type alloy) engine blocks. It was observed that the T7 treatment resulted in a significant reductionReduction of the strain/stress in the Al cylinder bridge (up to ~50% of the radial stress at the top of the bridge). In addition, the absence of the cast-in Fe liners allowed for unrestricted natural contraction of the Al bridge; leading to a combination of low tension and moderate compression as compared to the typically high tensile stress.

J. Stroh, D. Sediako, G. Byczynski, A. Lombardi, A. Paradowska

Molecular Dynamics Simulations of the Solidification of Pure Aluminium

Despite the continuous and remarkable development of experimental techniques for the investigation of microstructures and the growth of nuclei during the solidificationSolidification of metals, there are still unknown territories around the topic of nucleationNucleation during solidificationSolidification. Such nanoscale phenomena can be effectively observed by means of Molecular DynamicsMolecular Dynamics (MD) simulations which can provide a deep insight into the formation of nuclei and the induced crystal structures. In this study, MD simulations have been performed to investigate the solidificationSolidification of AluminiumAluminium melt and the effects of process parameters such as the cooling rate and hydrostatic pressurePressure on the final properties of the solidified material. A large number of AluminiumAluminium atoms have been used in order to investigate the grain growth over time solidificationSolidification. The population of the Face Centred Cubic (FCC) and amorphous (or non-crystalline) phases has been recorded during the evolution of the process to illustrate the nanoscale mechanisms during solidificationSolidification. Finally, the exothermic nature of the solidificationSolidification process has been effectively captured by measuring the temperature of the Al atoms during grain formation.

Michail Papanikolaou, Konstantinos Salonitis, Mark Jolly

Nanoindentation and Cavitation-Induced Fragmentation Study of Primary Al3Zr Intermetallics Formed in Al Alloys

Mechanical propertiesMechanical properties of primary Al3Zr crystals and their in situ fragmentationFragmentation behaviour under the influence of a single laser induced cavitationCavitation bubble have been investigated using nanoindentationNanoindentation and high-speed imagingHigh-speed imaging techniques, respectively. Linear loading of 10 mN was applied to the intermetallics embedded in the Al matrix using a geometrically well-defined diamond nano-indenter to obtain the mechanical propertiesMechanical properties at room temperature conditions. Primary Al3Zr crystals were also extracted by dissolving the aluminiumAluminium matrix of an Al-3wt% Zr alloy. The extracted primary crystals were also subjected to cavitationCavitation action in deionized water to image the fracture sequence in real time. FragmentationFragmentation of the studied intermetallics was recorded at 500,000 frames per second. Results showed that the intermetallic crystals fail by brittle fracture mode most likely due to the repeatedly-generated shock waves from the collapsing bubbles. The results were interpreted in terms of fracture mechanics using the nanoindentationNanoindentation results.

Abhinav Priyadarshi, Tungky Subroto, Marcello Conte, Koulis Pericelous, Dmitry Eskin, Paul Prentice, Iakovos Tzanakis

In Situ Neutron Diffraction Solidification Analyses of Rare Earth Reinforced Hypoeutectic and Hypereutectic Aluminum–Silicon Alloys

The recognised potential of rare earth (RERare earth (RE) metals) additions such as cerium (CeCe) and lanthanum (LaLa) for strengthening aluminum alloysAluminum alloys has led to an area of research focused on the development of new alloys, targeting powertrain applications that require high temperature strength and creep resistance. In an attempt to further improve the mechanical propertiesMechanical properties of the Al–Si system, this paper addresses the effects that RERare earth (RE) metals additions have on the microstructureMicrostructure and phase evolution during solidificationSolidification. This study presents the results of in situ solidificationSolidification studies using neutron diffractionNeutron diffraction and microstructural analyses using scanning electron microscopyElectron microscopy with energy-dispersive spectroscopy of Al7Si3.5RE and Al18Si8RE alloys, where numerical notation indicates composition in wt%. We find that the RERare earth (RE) metals additions lead to the formation of globular Al20Ti2(CeCe6LaNd) and rod-like Si3Al2(CeCe 3LaLa2Nd) intermetallics in the Al7Si3.5RE alloy. We also find that Si and Cu additions in the Al18Si8RE alloy transforms the solid structure of the rod-like Si3Al2(CeCe 3LaLa2Nd) intermetallic to a fibrous twin-layered material comprised of alternating Si3CeCe1Al1(LaLa6Nd3Cu2Pr) and Al5Si4CeCu(LaLa6Nd3Pr) constituents. Furthermore, the high RERare earth (RE) metals content in the Al18Si8RE alloy leads to a prolonged solidificationSolidification range which may increase the alloy’s susceptibility to porosity formation.

J. Stroh, D. Sediako, D. Weiss, V. K. Peterson

Influence of TiB2 Particles on Modification of Mg2Si Eutectic Phase in Al–Zn–Si–Mg–Cu Cast Alloys

In this study, the effect of TiB2 particles on the modification of eutectic phase in Al–Zn–Si–Mg–Cu system alloys is investigated. The microstructureMicrostructure showed that an excellent effect can be achieved after the addition of TiB2 particles. The morphology of eutectic Mg2Si changed from large Chinese script to fine polygonal shape with a significant reductionReduction in size. Modified eutectic Mg2Si particles were investigated using an optical microscope and field emission scanning/transmission electron microscope, and it was confirmed that TiB2 particles acted as nucleationNucleation sites for the eutectic Mg2Si phase, and the grain size change of Al–Zn–Si–Mg–Cu alloy with increasing TiB2 contents was analyzed by polarizing microscope. The mechanical propertiesMechanical properties were also improved by the modified of eutectic Mg2Si phase. This manuscript also investigated the reason for the improvement in mechanical propertiesMechanical properties with the modification of the microstructures. Upon these results, a possible mechanism of eutectic Mg2Si phase modificationPhase modification by the addition of TiB2 particles is proposed.

Byung Joo Kim, Sung Su Jung, Yong Ho Park, Young Cheol Lee

A Statistical Analysis to Study the Effect of Silicon Content, Surface Roughness, Droplet Size and Elapsed Time on Wettability of Hypoeutectic Cast Aluminum–Silicon Alloys

In this study, the effect of silicon content, surface roughness, water droplet size, and elapsed time on contact angle (CA) of AluminumAluminum-Silicon alloys were examined. To study wettability the static water contact angle was measured on a given sample using a goniometer. A laser confocal microscopy was used for measuring surface roughness. A full factorial designFactorial design was utilized for the designDesign of the experiment that includes all possible combinations of the independent factors and their levels (120 combinations). CA for each combination was measured three times, so in total 360 CA measurements were performed. To find the significant factors in CA variation and correlation between the significant factors and CA, Analysis of VarianceAnalysis of Variance (ANOVA) and Regression AnalysisRegression Analysis were performed, respectively. A significance level (α) of 0.05 was used for all statistical analyses. Contact angle values averaged 77° ± 5° with maximum value of 90º and minimum value of 64º, respectively. ANOVA results show that surface roughness and droplet size are significant factors. Regression analysisRegression Analysis shows that CA increases by increasing surface roughness and water droplet size.

Amir Kordijazi, Swaroop Kumar Behera, Omid Akbarzadeh, Marco Povolo, Pradeep Rohatgi

Aluminum Trace Elements Analyses Using Epsilon 1 Meso EDXRF Technique

The amount of alloying materials and trace elements in aluminumAluminum metal are usually measured by Optical emission spectroscopy (OESOES) technique, which is an accurate and reliable method applied in most aluminumAluminum smelters and downstream industries. In absence of an OESOES machine, it is extremely difficult to decide the amount of alloying materials required for each aluminumAluminum alloy, and certification of final aluminumAluminum product cannot be carried out. In this study, a new analytical application is developed as a backup for OESOES using Epsilon1 Meso Energy Dispersive machine (EDXRFEDXRF). The application is capable to measure the trace elements in aluminumAluminum metal with high accuracy.

Hussain Al Halwachi

Effect of Cooling Rate During Solidification of Aluminum–Chromium Alloy

Controlling the distribution of alloying elements in aluminum castingAluminum Casting and designing new processing practices are supported by an enhanced understanding of the thermodynamics and kinetics of solidificationSolidification at industrial scales. While the behavior of eutectic forming elements such as copper has received a lot of attention, the interactions of peritectic-forming elements such as chromium is understudied. We herein use a time-dependent nucleationNucleation model and evaluate its prediction for industrially-observed cooling ratesCooling rates . The predictions are obtained from the calculation of the incubation time of nuclei in the liquid. This characteristic time is computed at various temperatures, and the results are presented in the form of a time-temperature diagram. The diagrams enable to compare theoretical cooling ratesCooling rates for phase selection for industrially relevant practices such as DC castingDC casting and Twin roll castingTwin roll casting .

G. Muthusamy, S. Wagstaff, A. Allanore

Effects of Si on the Electrical Conductivity, Microhardness, Microstructure and Hot Tearing of Al–0.8Fe–0.5Mg–0.4Ni Alloys

Electrified automotive powertrains require new Al alloys with high castability and high electrical conductivityElectrical conductivity . This research presents the effects of Si on the electrical conductivityElectrical conductivity , microhardnessMicrohardness , microstructureMicrostructure and hot tearingHot tearing of Al–0.8 wt% Fe–0.5 wt% Mg–0.4 wt% Ni–x wt% Si alloys. The Al–Fe–Mg–Ni–Si alloys were prepared by mixing pure Al, Fe, and Ni, as well as Al–50 wt% Mg and Al-50 wt% Si master alloys at 720 °C. Silicon contents of 0.15 and 0.30 wt% were examined. The alloys were characterized using microhardnessMicrohardness testing, optical and electron microscopyElectron microscopy , X-ray diffraction, electrical conductivityElectrical conductivity measurements and hot tearingHot tearing susceptibility testing. The microstructureMicrostructure of the Al–Fe–Mg–Ni–Si alloys contained fibrous as well as elongated or rounded Al3Ni and Al9FeNi intermetallics, with Mg and Si contained in the Al solid solution. Increasing Si content from 0.15 to 0.30 wt% in the Al–Fe–Mg–Ni–Si alloys resulted in more rounded intermetallics but nearly constant microhardnessMicrohardness (~46 HV) and electrical conductivityElectrical conductivity (~50 %IACS). The hot tearingHot tearing susceptibility of the Al–Fe–Mg–Ni–Si alloys was more severe than a modified A380 alloy but did not result in a complete separation of the castingCasting .

Stephanie Kotiadis, Adam Zimmer, Abdallah Elsayed, Eli Vandersluis, C. Ravindran

The Efficacy of Replacing Metallic Cerium in Aluminum–Cerium Alloys with LREE Mischmetal

The ongoing development of aluminum–cerium alloysAluminum–Cerium Alloys has produced materials exhibiting elevated temperatureElevated temperature mechanical propertyMechanical properties retention, long term microstructural stability, and flexible processability compared to traditional aluminum alloysAluminum alloys, accommodating the growing demand for high temperature aluminum alloysAluminum alloys not requiring the use of high-cost elements like scandiumScandium. To date, reported Al–CeCe alloy compositions contain large amounts of elemental cerium. Mischmetal (MM), a mixture of lanthanum, cerium, and other light rare earth elements (LREE) is less expensive and more available than pure cerium. The chemical similarity of the LREEs means there is possibility to use MM as the primary alloy addition, lowering alloy cost. This talk will report the effect of using MM instead of cerium in a 12 wt% binary alloy on mechanical propertiesMechanical properties, phase constituency, thermal stability, and load sharing. Results will show that MM can be substituted completely for cerium with a mostly positive impact on alloy performance.

Zachary C. Sims, David Weiss, Orlando Rios, Hunter B. Henderson, Michael S. Kesler, Scott K. McCall, Michael J. Thompson, Aurelien Perron, Emily E. Moore

Effects of Sc and Y on the As-Cast Microstructure of AA6086

AA6086 is a novel Al–Mg–SiAl–Mg–Si alloy that contains more Si and Cu than AA6082, as well as 0.15–0.25 wt% Zr. This new alloy is distinguished by its improved tensile strength and hardness, with a convenient ductility (max. UTS = 490 MPa, Brinell hardness 140 HBW, elongation at fracture 10%). Additions of rare-earth elements can further improve these properties. In order to clarify their influence, we prepared several alloys containing either individual or combined additions of Sc and Y in the range 0.2–1.0% Sc and 0.1–1.0% Y. The alloys were melted and then cast into copper moulds. They were investigated by optical microscopy and SEM with EDS. There are several microstructural constituents in the as-cast state. The additions of Sc and Y resulted in the appearance of scandiumScandium - and yttriumYttrium -rich phases. The effects of Sc and Y on the grain size were determined using the ASTM E112 standard. With small additions of Sc (0.2 wt%) we already detected a difference in the grain size for the range of 1.5 G in comparison with AA6086. Larger additions of Sc (1 wt%) greatly increased the grain-size number, up to 4.5 G. In the centre of the grains were Al3(Sc, Zr) particles, which are effective grain refiners. However, the grain-refinement effects were minor when we used Y. The additions of Sc and Y also affected the formation of α-AlMnSi and the solidificationSolidification sequence, which will be explained in detail.

Sandi Žist, Varužan Kevorkijan, Matej Steinacher, Franc Zupanič

Ternary Interactions and Implications for Third Element Alloying Potency in Al–Ce-Based Alloys

Recently developed Al-CeCe -based alloys offer numerous beneficial attributes, including high temperature strength retention, resistance to microstructural coarseningCoarsening , and excellent castability. Binary alloys around the eutectic composition of ~11 wt% CeCe contain a characteristic large volume fraction of eutectic Al11CeCe 3 laths. However, further alloying additions to improve properties can stabilize a myriad of ternary Al-CeCe -X phases that complicate alloying efficacy in unexpected ways, as relative intermetallic stability often changes between solidificationSolidification and solutionizing temperatures. Unlike in many Al alloys that can be solution treated to a single phase, Al-CeCe and Al-CeCe -X intermetallics form during solidificationSolidification and their morphology is largely retained during heat treatment, similar to composite materials. This morphological stability remains even after stoichiometric changes. Here, empirical relationships for third element alloying potency in Al-CeCe -based alloys are derived, using Mg and Cu additions as prototypes for non-interacting and interacting elements, respectively. The relationships pair analytical calculations with empirical phase composition measurements as an aid to alloy designAlloy Design . While not a substitute for CALPHAD-based approaches, the empirical approach based on direct measurement can supplement in Al-CeCe -based alloys where the low diffusivity of CeCe often results in non-equilibrium phase compositions.

Hunter B. Henderson, David Weiss, Zachary C. Sims, Michael J. Thompson, Emily E. Moore, Aurélien Perron, Fanqiang Meng, Ryan T. Ott, Orlando Rios

Development and Analysis of Al7075 Alloy Materials Using Press and Sinter Processing

Al7075Al7075 alloy composition powders of ready to press Alumix 431/D and gas atomized pre-alloyed Al7075Al7075 were consolidated using press and sinter processingPress and sinter processing for structural application. Both powders exhibit similar overall compositions except for a small Sn content in Alumix 431/D and are very compressible using admixed and die wall lubricants. Green compacts were delubed and sintered in N2 (g) for 60 min. at temperatures guided by thermal analysis of powders. Sintering results show that Alumix 431/D increases from green density to near theoretical density due to a low melting temperature transient liquid phase that forms at the majority of powder particle interfaces. Alternatively, pre-alloyed Al7075Al7075 does not increases in density during sintering from green density due to the formation of only a supersolidus transient liquid at the melting temperature of the powder. The supersolidus liquid phase that forms during sintering of Al7075Al7075 powder does so at a minority of powder particle interfaces thus not facilitating sintering density increase. These results indicate that development of Al7075Al7075 materials for net or near shape processingNear shape processing using press and sinter methods should technically work towards near theoretical density materials exhibiting homogeneous microstructures and compositions to maximize structural properties.

Steven C. Johnson, Corey D. Clark, Jason S. Alvarez

Formation of Rare Earth Intermetallics in Al–Cu Cast Alloys

The present research study aimed at investigating the effect of additions of CeCe and LaLa rare earth (RERare earth (RE) metals ) elements on intermetallic formation in Al-1.2Si-2.4Cu-0.4 Mg-0.4Fe-0.6Mn-0.15Ti (wt%) alloy, coded B0. Microstructural characteristics were examined under low solidification rateSolidification rate (~0.7°C/s). The result show that two main types of RERare earth (RE) metals -containing intermetallic phases were formed: (i) a grey phase in the form of sludge, with a fixed composition Al21Ti2RE (CeCe /LaLa ), and (ii) white RERare earth (RE) metals -containing intermetallic phases (resulting from reaction of the RERare earth (RE) metals (CeCe /LaLa ) with Si, Fe, and Cu); the latter exhibited several compositions: Al11RE(CeCe /LaLa )3(Cu,Fe)4Si2, Al4CeCe 3Si2, Al5LaLa 3Si2 and Al6LaLa 2(Cu,Fe)2Si.

M. G. Mahmoud, A. M. Samuel, H. W. Doty, F. H. Samuel

Retrogression Forming and Reaging of AA7075-T6 Alclad to Produce Stampings with Peak Strength

A retrogressionRetrogression heat treatment was combined with simultaneous warm forming to produce cross-shaped stampings from AA7075AA7075-T6 Alclad sheet. This process is termed retrogressionRetrogression forming. A maximum-allowed-retrogressionRetrogression-forming-time, which includes sheet heat up, transfer, and stamping, was predicted by calculation to achieve peak-aged strength through a single reaging heat treatment after forming. Sheets of 1.6-mm-thick AA7075AA7075-T6 Alclad were stamped at 200 °C to a depth of 45 mm within 2 s without splitting. The formed geometry exhibits a complexity appropriate to automotive structural components. These stampings were then subjected to one of two reaging heat treatments. A full reaging heat treatment of 120 °C for 24 h produced strength levels in excess of the original, peak-aged T6 alloy sheet. A simulated paint bake heat treatment at 185 °C for 25 min recovered 95% of the strength lost during warm forming. Successful retrogressionRetrogression forming and reaging of AA7075AA7075-T6 provides new possibilities for stamping high-strengthHigh-strength aluminum alloysAluminum alloys into complex geometries without sacrificing strength.

Katherine E. Rader, Jon T. Carter, Louis G. Hector, Eric M. Taleff

High Cycle Fatigue Properties of the Zr-Modified Al–Si–Cu–Mg Alloy at Elevated Temperatures

The Al–Si–Cu–Mg alloy with 0.14 wt%Zr addition has been studied against the counterparts of commercially used EN-AC-42000 (Al7Si0.5Cu) baseline alloy for the effect of Zr on the high cycle fatigueFatigue (HCF) properties at elevated temperatures. It was found that the fatigueFatigue life was significantly improved by 8-10 times at the high stress amplitude of 140 MPa in the Zr-modified alloy at all different temperatures. The fatigueFatigue strength coefficient, $$ \sigma_{f}^{{\prime }} $$, of the baseline alloy was 574.9, 589.8, and 514.8 MPa at 150, 200, and 250 °C, respectively, which was greatly increased to 1412.3, 620.1, and 821.6 MPa for the Zr-modified alloy. The improved fatigueFatigue properties could be mainly ascribed to: (1) the refined microstructureMicrostructure, with α-Al grain size decreasing from 335 ± 18 to 253 ± 41 μm and the secondary dendrite arm spacing (SDAS) dropping from 39 to 28 μm; (2) the reduced porosity; and (3) the additional precipitatesPrecipitates strengthening effect by the Al–Si–Zr–Ti dispersoidsDispersoids.

Guangyu Liu, Paul Blake, Shouxun Ji

Effect of Mo on Elevated-Temperature Low-Cycle Fatigue Behavior of Al-Si 356 Cast Alloy

Components of diesel engines are often subjected to cyclic loading at elevated temperatureElevated temperature during operation, which may cause their fatal fatigueFatigue failure. In this study, elevated-temperature low-cycle fatigueLow-cycle fatigue (LCF) tests were conducted at 300 °C on Al-Si 356 cast alloys with MoMo addition. Various strain amplitudes of 0.1, 0.2, 0.4 and 0.6% was applied. Results showed that a high volume of finer dispersoidsDispersoids formed with addition of MoMo. Compared with the base alloy free of MoMo, a higher fatigueFatigue strength but reduced plastic strain at all studied strain amplitudes was obtained in the alloy containing MoMo. Smaller fatigueFatigue striation spacing was observed in MoMo-containing alloy, indicating its better fatigueFatigue crack propagation resistance. However, the total LCF cycle at 300 °C in the alloy with MoMo was moderately decreased due to the fast growth of crack to the final rupture. FatigueFatigue parameters were calculated from test data for fatigueFatigue life estimation.

S. Chen, K. Liu, X.-G. Chen

State Parameter-Based Simulation of Temperature- and Strain Rate Dependent Flow Curves of Al-Alloys

When simulating the material behavior during thermo-mechanical processes, the understanding of the microstructureMicrostructure evolution is fundamental. Therefore, state parameter-based models are utilized to describe physical effects such as work hardeningWork hardening , precipitation hardening, solid solution hardening and cross core diffusion. Using the thermo-kinetic software package MatCalc, temperature- and strain rate dependent flow curves of compression tests are successfully simulated. The theoretical background of the underlying physical models and the influence of alloying elements on the cross core diffusion behavior are discussed. Various Al-alloys are investigated and the experimentally obtained flow curves are evaluated in terms of initial strain hardening rate, initial yield stress and saturation stress. In Al-alloys, especially the effect of Mg is dominant due to its ability to diffuse from the compression side to the tension side of the dislocations core, leading to additional barriers for the dislocation movement.

Bernhard Viernstein, Philipp Schumacher, Benjamin Milkereit, Ernst Kozeschnik

Coarsening-Resistance of a Severely Deformed Al-0.2 wt% Sc Alloy

Second-phase Al3Sc particles play an important role in several aspects of material performance. These include increasing strength, stabilizing microstructureMicrostructure and increasing recrystallization temperature and thermal stability. The present work was conducted to investigate the stability of Al3Sc particles in a severely deformed Al-0.25 wt% Sc alloy at room temperature in comparison to that of Al2Cu precipitatesPrecipitates in an Al-Cu alloyAl-Cu alloy . Microstructural examination and hardness tests showed that the Al3Sc particles were coarseningCoarsening resistant with substantially higher stability than Al2Cu and the hardness of the Al-0.25Sc alloy remained almost constant while an apparent hardness drop was observed for the Al-Cu alloyAl-Cu alloy .

Yan Huang

The Effect of Modified Strain-Induced Melt Activation (Modified SIMA) Process on the Microstructure and Mechanical Properties of Al-7Si Alloy

In this study, hypo-eutectic aluminumAluminum -silicon (Al-Si) alloy has been developed through modified strain-induced melt activation (modified SIMA) process. Microstructural features of modified SIMA processed Al-7Si alloy is fine, globular α-Al grain and uniformly distributed fragmented eutectic silicon. The developed alloy shows remarkable ultimate tensile strength (UTS, 204 MPa) with exceptionally achieved ductility (El, 30%). Globular morphology of α-Al grain and fine fibrous, uniformly distributed eutectic silicon maintain a proper balance in the strength and ductility of modified SIMA processed Al-7Si alloyAl-7Si alloy .

Chandan Choudhary, K. L. Sahoo, D. Mandal

Effect of Mg on Flow Behavior of Al–Mg Alloys and Its Constitutive Modeling Using Finite Element Analysis

Al–Mg alloysAl–Mg alloys are one of the most widely used materials for automotive and marine applications due to their relatively higher strength and superior corrosion properties in marine environmentEnvironment. However, with increasing magnesium content in these alloys, the engineering workability decreases. The flow behaviorFlow behavior of AA5052 and AA5083 alloys were studied by performing the tensile test along the rolling direction at various temperatures and strain rates, ranging from room temperature (RT)—400 °C and 0.001–1 s−1 respectively, using Gleeble®Gleeble® 3800 thermomechanical simulator to study the effect of Mg content on various state variables. These experiments were used to determine material model coefficients at different test conditions for both the alloys. Johnson–Cook (JC) material model was used to describe the material behavior with finite element simulations in commercial finite element analysis package ABAQUS™ABAQUS™. The simulationSimulation results based on a calibrated JC model depicted a close agreement with the experimental results.

Shahin Ahmad, Vilas Tathavadkar, Alankar Alankar, K. Narasimhan

Influence of Thermal Treatment and Design Parameters on the Fatigue Life of Automotive Control Arm Fabricated from A357 Semi-solid Alloy

Suspension control arm is considered one of the most significant automotive components as a mechanical part that is responsible of linking the wheels of the vehicle to the chassis. The materials and designDesign of such components are the matter of research that mainly focus on the enhancement of its performance considering safety and cost factors. FatigueFatigue failure is considered a common problem that faces these parts due to variable dynamic loadings. Currently, the research trend is to manufacture this part from aluminumAluminum A357 semi-solidA357 Semi-solid alloys, produced by Rheocasting using SEED technology, due to its significant characteristic and performance. This work aims at investigating an innovative thermal treatment and designDesign parameters to enhance the fatigueFatigue life of the automotive control arm. The results revealed that the interrupted thermal aging as well as the modified trussed designDesign show superior quality and performance concerning the fatigueFatigue life.

Mohamed Attia, Khaled Ragab, Mohamed Bouazara, X. Grant Chen

The Formation of Al6(Fe, Mn) Phase in Die-Cast Al–Mg Alloys

In aluminium alloysAluminium alloys, ironIron is a common impurity as it is unavoidably picked up in practice. The excessive Fe is strongly prone to form various intermetallic phases. These Fe-rich intermetallics are generally brittle and act as stress raisers to weaken the coherence with Al matrix, therefore decreasing elongation. However, Fe addition in Al–Mg alloysAl–Mg alloys may be beneficial because of the improvement in the yield strength with the scarification of ductility of die-castDie-cast aluminium alloysAluminium alloys. The morphology of intermetallic phases has a vital effect on the properties of aluminium alloysAluminium alloys. In the present work, the 3D morphology of Al6(Fe, Mn)Al6(Fe, Mn) in die-castDie-cast Al–MgAl–Mg–Mn alloys with different levels of Fe contents were revealed. The formation of Al6 (Fe, Mn)Al6(Fe, Mn) was also studied through crystal features and solidificationSolidification behaviours.

Xiangzhen Zhu, Shouxun Ji

Spark Plasma Sintering of Graphene Nanoplatelets Reinforced Aluminium 6061 Alloy Composites

Over the years, high performance lightweight aluminiumAluminium matrix composites have, mainly due to their excellent mechanical propertiesMechanical properties , found wide applications in automobile and aerospace applications. In the present study, Graphene NanoPlatelets based reinforced aluminium alloyAluminium alloys AA6061 composites have been prepared through spark plasma sintering with four different loadings, i.e. 0.1, 0.5, 1 and 3 wt%. Through property characterisation of the obtained composites, it was established that a higher content of nano reinforcement had a substantial effect on the resulting microstructureMicrostructure , as well as on the electrical conductivityElectrical conductivity that proved to increase due to uniform distribution of the graphene network around the grains. An increase in the hardness and compressive strength was also obtained. The associated strengthening mechanism is discussed. A 2-dimensional physical model based on the bridging effect of graphene nanoplatelets in a composite matrix is presented, and its correlation with experimental results is discussed.

Mahmood Khan, Rafi Ud-Din, Abdul Wadood, Wilayat Husain Syed, Shahid Akhtar, Ragnhild Elizabeth Aune

Effects of Mn and Mo Micro-additions on Al–Zr–Sc–Er–Si Mechanical Properties

Dilute Al–Zr–Sc–Er–Si alloys strengthened by coherent L12 Al3(Sc, Er, Zr) nanoprecipitates have potential applications at temperatures higher than 400 °C. In this research, the effects of micro-additions of 0.25 at.% Mn and/or 0.10 at.% MoMo to a dilute Al-0.08Zr-0.014Sc-0.008Er-0.09Si (at.%) alloy were investigated using atom-probe tomographyAtom-probe tomography , as well as mechanical testing after different heat treatments. Molybdenum and manganese result in solid-solution strengthening. Aging at 400 °C leads to the formation of core-shell (L12 structure) nanoprecipitates, with Mn partitioning to the core, and MoMo partitioning to both the core and nanoprecipitate/matrix interface. Manganese-modified L12 nanoprecipitates exhibit a higher number density, while MolybdenumMolybdenum -modified L12 nanoprecipitates display an improved coarseningCoarsening resistance.

Shipeng Shu, Anthony De Luca, David N. Seidman, David C. Dunand

Nanotreating High-Zinc Al–Zn–Mg–Cu Alloy by TiC Nanoparticles

High-zinc Al–Zn–Mg–Cu alloys offer the highest strength among all aluminum alloysAluminum alloys mostly due to high-volume precipitatesPrecipitates after heat treatment. However, the high zinc content makes the alloys more sensitive to hot cracking and stress corrosion cracking during solidificationSolidification and solid state processing. Recently, a revolutionary method, Nanotreating, becomes significant in metals processing by introducing ceramic nanoparticles into metals. It is an emerging method to modify the microstructures (both primary and secondary phases) during solidificationSolidification, deformation and heat treatment. In this work, In situ TiC nanoparticles were added into Al–8.6Zn–2.8Mg–1.8Cu alloy to study the nanotreating effects. The grain size of the as-cast alloy has been reduced significantly from 272.3 μm to about 30.4 μm by 1 vol% TiC nanoparticles. The size of remaining large secondary phase after heat treatment were reduced significantly as well. Furthermore, the hardness was enhanced. Nanotreating is promising as an effective approach to modify the microstructureMicrostructure, relieve the manufacturing difficulty, and enhance the properties of the high-zinc Al–Zn–Mg–Cu alloys for widespread applications.

Jie Yuan, Min Zuo, Maximilian Sokoluk, Gongcheng Yao, Shuaihang Pan, Xiaochun Li

Microstructure and Mechanical Response of an Artificially Aged Al–Mg–Si Alloy: Experiments and Modeling

An extrusion of an Al-0.65Mg-0.92Si alloy (wt%) containing 0.2 wt% Cr was selected and its isothermal aging response at 170 °C was characterized. Tensile properties were measured in the T4 (6 months at room temperature) and T6 (170 °C/10 h) conditions and differences in the yield strength and the work-hardening response are attributed to the β″ precipitatesPrecipitates that result during artificial aging. Single crystal micropillars with [111] loading axis were milled from the alloy in the T6 condition, tested in uniaxial compression and the data were analyzed to obtain the critical resolved shear stress. MicrostructureMicrostructure in the T4 and T6 conditions was investigated by transmission electron microscopyElectron microscopy and dispersoidsDispersoids chemistry and precipitate type, morphology and size distribution were quantified; an analytical model for precipitation kineticsPrecipitation kinetics of β″ precipitatesPrecipitates by assuming a cylindrical morphology and an aspect ratio that changed with aging time, has been developed and precipitatesPrecipitates size, distribution, volume fraction and residual Mg and Si content in solid solution are determined and compared to experimental results. The intent is to eventually extend the precipitation model to understand the effect of alloy composition on precipitation kineticsPrecipitation kinetics and then relate microstructureMicrostructure evolution to flow behaviorFlow behavior through yield strength and work hardeningWork hardening .

Yoojin Kim, Sharvan Kumar

Effect of Zn Additions on the Mechanical Properties of High Strength Al–Si–Mg–Cu Alloys

In this study, the effect of Zn additionsZn additions on the mechanical propertiesMechanical properties of Al–Si–Mg–Cu alloys was investigated. From the results, it has been found that the formation of Mg–Zn intermetallic compounds is considered to be the main reason for the sharp changes in the mechanical propertiesMechanical properties of this alloy system. The microstructureMicrostructure showed that Mg–Zn intermetallic compounds were formed between the reinforcement phase like Mg2Si phase and the matrix became more brittle as the amount of Zn addition was increased. Upon these results, we could confirm that the formation of Mg–Zn intermetallic compounds and brittle matrix are the main reasons for the remarkable changes in the mechanical propertiesMechanical properties of this alloy system.

Sung Su Jung, Soo Been Hwang, Byung Joo Kim, Yong Ho Park, Young Cheol Lee

Utilization of 3D Printed Materials in Expendable Pattern Casting Process

While lost foam castingCasting process offers advantages of producing complex parts without the needs of parting line, draft and core, this process requires long lead time and only works for high volume applications due to the tooling requirements. With recent developments of 3D printing3D Printing technology, the limitations of this process can be mitigated. UtilizationUtilization of 3D printed materials instead of foam will allow the production of pattern materials at lower cost and shorter lead time, and also, low-volume production. The objective of this study was to explore the feasibility of producing cast parts using expendable castingCasting process with 3D printed materials (PLA, ABS, and PVA) as patterns. These materials were printed in a shape of fluidity spiralFluidity Spiral with different sizes and infill designs, and were then poured with A356.0 AluminumAluminum. Results showed that this process can be used as an alternative method to produce cast aluminumAluminum components.

Dika Handayani, Nicole Wagner, Victor Okhuysen, Michael Seitz, Kyle Garibaldi

Hemming Evolution of 6xxx Aluminum Alloys in the Course of Natural Aging Following the Continuous Annealing

The thermomechanical processing steps immediately following the continuous annealing in a production line were simulated in the lab to understand the evolution of hemmingHemming behavior of AA6016 and AA6005A in the course of natural agingNatural aging (NA). After solution heat treatment and quench samples received various post-treatments namely pre-straining (PS) and pre-aging (PA) followed by NA. The results show that the hemmingHemming performance of both alloys significantly drop immediately after quenching followed by a milder decrease up to 1 month of NA. The significant drop of the work hardeningWork hardening and dynamic recoveryRecovery rate during the first hour of NA after quench may explain the degradation of hemmingHemming . PS shows a similar effect as NA on the work hardeningWork hardening rate without affecting the dynamic recoveryRecovery rate noticeably. PA decreases the work hardeningWork hardening and the dynamic recoveryRecovery rate considerably.

M. Lalpoor, E. Lambrechts, A. Miroux, C. Bollmann, C. Yu

The Effect of Deformation Mode and Microstructure on the IGC Susceptibility of Al–Mg–Si–Cu Alloys for Automotive Applications

Intergranular corrosionIntergranular corrosion (IGC) can occur in 6000 series alloys due to the formation of corrosion-active Mg2Si phases or copper-enriched nanofilms at the grain boundaries. The formation of these films highly depends on the alloy composition and thermomechanical history such as the deformation degree and the grain morphologyGrain morphology . The present study explores the underlying mechanisms of IGC of different industrially-used extruded, rolled, and cast 6000 series aluminumAluminum alloys with high copper contents using standardized immersion tests (DIN EN ISO 11846 B). A particular focus is set on the influence of processing parameters on the grain size and morphology and their effect on the corrosion susceptibility. The results are correlated to the microstructureMicrostructure using optical light microscopy, Barker etchings and scanning electron microscopy. The corrosion susceptibility as well as the corrosion mechanism was found to be highly dependent on the processing routeProcessing route , the resulting grain structureStructure and the dislocation accumulation through deformation.

R. Müller-Jena, J. Becker, T. Beyer, T. Hentschel, M. Rosefort, A. Stieben, D. Zander

Evolution of Grain Refinement in AA5083 Sheet Metal Processed by ECAP

Achieving superplasticity requires a homogeneous, fine-grained microstructureMicrostructure with (primarily) globular grains. Equal-Channel Angular Pressing (ECAPECAP) is an established method that produces considerable grain refinement. While there is substantial knowledge about work hardening and grain refinement during ECAPECAP of bulk materials, there is only little information on the effect of ECAPECAP on sheet materials. In the present study, AA5083AA5083 aluminumAluminum sheets are deformed by single and multiple passes using a 120° die that enables processing of sheet metals following novel ECAPECAP routes, like route D. The effect of different ECA-processing routes on microstructural evolution is characterized by EBSD and supported by additional micro-hardness measurements. Our first results presented here clearly show that microstructural evolution during sheet metal ECAPECAP is strongly path dependent. Our study highlights the challenges of sheet metal ECAPECAP (e.g., microstructural gradients) for producing ultrafine-grained microstructures for superplastic applications.

Christian Illgen, Philipp Frint, Maximilian Gruber, Wolfram Volk, Martin F.-X. Wagner

Mechanical and Microstructural Behavior of Dissimilar AA2014-T6 and AA7075-T6 Aluminium Alloys Joined by Friction Stir Welding

The present work aims to investigate the mechanical and microstructural properties of dissimilar welding of 2014-T6 and 7075-T6 aluminiumAluminium alloys of 6 mm thick sheets, using butt welded friction stir weldingFriction stir welding . The two distinct materials welded with the perpendicular to the rolling direction of the dissimilar weld zone. The welded joint was tested in tension at room temperature to investigate the mechanical response and also to observe the differences with the parent materials. The diversity in the properties across the weld and its material mixing behavior have considered by resolving the thermal cycle, hardness test, and microstructural analysis. Plastic deformation along with recrystallization during the welding process resulted in the formation of distinct zones which could be identified by their respective microstructures. SEM/EDS analysis was carried out to analysis the precipitates, which influenced the properties of the joints. Based on the present study, 840 rpm with 30 mm/min weld speed seemed to be optimum.

Mohammad Adil, Jyoti Mukhopadhyay

High Strength Nanotreated Filler Material for TIG Welding of AA6061

Incorporating structural parts into functional assemblies using a variety of techniques, such as bolting, riveting, brazing, and welding is important for today’s industry and society. When joining AA6061 by Tungsten Inert Gas welding, designers so far had to rely on filler materials, such as ER5356 and ER4043 to dilute the joints melting zone and therefore suppress AA6061’s intrinsic susceptibility to hot cracking. However, welding with dissimilar alloys as filler materials is always a tradeoff between enabling the material for fusion welding and accepting drawbacks of the diluted melting zone’s properties. In this work, a low volume fraction of titanium carbide particles were incorporated into AA6061 to fabricate filler rods. The fabricated AA6061-TiC filler material was further used to TIG weld AA6061 base material. The welds produced by using the nanotreated filler rods were free of cracks and showed exceptional mechanical propertiesMechanical properties in both as welded and post weld heat treatment condition. The new nanotreated AA6061 filler materials offer a great potential for widespread applications.

Maximilian Sokoluk, Gongcheng Yao, Shuaihang Pan, Chezheng Cao, Xiaochun Li

Optimization of Thermo-Mechanical Processes of Continuous Casting Products Using High Magnesium Aluminum Alloys in Automotive Industry Applications

5XXX series alloys are preferred in the automotiveAutomotive industry due to its high strength and formability. 5XXX series aluminumAluminum alloys, which are difficult to produce under the scope of our work, are sustainable and suitable for high quality expectations of automotiveAutomotive sector; The conditions of continuous castingContinuous casting, which enable efficient production, have been determined and the thermo-mechanical processes required by the final products have been developed. 57545754 aluminumAluminum alloy sheets, which have many applications in the automotiveAutomotive sector, come to the fore and increase their usage areas every day due to its high strength, weldability and deep formability properties. In the analysis of the study, industrial scale production and laboratory prototype studies were evaluated comparatively for each production stage. In the context of these evaluations, microstructureMicrostructure analysis and thermo-mechanical propertiesMechanical properties were investigated in detail. In addition, due to the high visual expectation of the automotiveAutomotive sector, surface properties at every stage of production were analyzed by measurable methods.

Görkem Demir, Ali Ulaş Malcıoğlu, Sümbüle Sağdiç, Ali Ulus, Salim Aslanlar, Erdinç İlhan

Plastic Flow of AA6013-T6 at Elevated Temperatures and Subsequent Reaging to Regain Full Strength

Combining a retrogressionRetrogression heat treatment with simultaneous warm formingForming can increase the formability of peak-aged, high-strengthHigh-strength aluminumAluminum alloys while allowing peak-aged strength to be recovered through a single reaging heat treatment after formingForming . This process is termed retrogressionRetrogression -forming Forming -and-reaging (RFRA). This study investigates the applicability of RFRA to AA6013AA6013 -T6 sheet material. Elevated-temperature tensile tests were performed at temperatures from 230 to 250 °C and strain rates from 3.2 × 10−3 to 10−1 s−1. Tensile tests were followed by reaging with a simulated paint-bake heat treatment. Flow stress at a true strain of 0.10 ranges from 230 MPa (250 °C and 3.2 × 10−3 s−1) to 290 MPa (230 °C and 10−1 s−1), significantly lower than the room-temperature yield strength of 360 MPa in the T6 condition. The average elongation to rupture and reduction in area from elevated-temperature tests are 22% and 56%, respectively, which are similar to the room-temperature values for the T4 condition. Elevated-temperature testing reduced material hardness compared to the original T6 condition. Subsequent reaging with a simulated paint-bake raised hardness to 96% of the T6 condition in un-deformed material, but slightly decreased the hardness of the deformed material. Recommendations for implementing RFRA of AA6013AA6013 -T6 are presented.

Katherine E. Rader, Jon T. Carter, Louis G. Hector, Eric M. Taleff

Influence of Chemical Composition and Pre-deformation on the Age-Hardening Response of Al-Mg-Si Alloys

AlMgSi (6xxx) alloys are widely used in the lightweight construction of automotiveAutomotive structures. In addition to light weighting, the recycling of aluminumAluminum alloys plays an important role for the optimization of the carbon footprintCarbon footprint in the automotiveAutomotive industry. On the one hand, optimized AlMgSi alloys require a narrow tolerance window, both for chemistry and process parameters, and on the other hand, increasing recycling rates are a challenge to achieve a defined chemistry. In this work, the influences of alloy chemistry, grain size, pre-deformation and heat treatment parameters such as quench rate and time/temperature profiles were analyzed. 20 different AlMgSi alloys, both with and without Cu, quench rates from 500 K/min to 30,000 K/min and ageing procedures including and excluding pre-deformation and natural ageing were systematically examined. For the alloy 6082 (AlMgSiMn) yield strength values above 400 MPa and elongation to fracture values exceeding 20% were measured.

A. Wimmer

Hot Deformation and Die-Quenching of 6000-Series Alloys—The Effect of Quench-Interruption Temperature

The automotiveAutomotive industry face demands to produce lightweight vehicles and substituting steel with aluminiumAluminium is a straightforward solution. Age hardenable aluminiumAluminium alloys are attractive candidates when the aim is a combination of high strength and good ductility. To obtain a solution that is suitable for high-volume production, an integrated hot formingForming and in-die quenching process has been developed. The method involves less operations and less handling than the conventional production process. However, the developed method changes the temperature exposure of the part and hence alters the precipitation and clustering sequence during hardening. In the present work, the effect of the modified temperature sequence has been investigated and, in particular, the effect of direct artificial ageing (DAA) has been studied. The potential benefits of DAA are less time needed for production and less space needed for storage. A lab-scale set-up, with the ability to simulate the industrial scale integrated formingForming and quenching method, has been built. By application of a water-cooled compression tool combined with subsequent age-hardening we have explored the effect of the in-die quenching on three different age hardenable alloys. The temperature experienced by the blank has been measured throughout the process, and the effect of variations in the quench-interruption temperature has been investigated. For AA6082, the results indicate that for selected temperatures, the effect of changing the closed-die time is minimal, and that the effect of room temperature storage (RTS) is negligible.

Tanja Pettersen, Benedikte Jørgensen Myrold, Calin Daniel Marioara, Ola Jensrud

Descriptors and Predictors: New Tools for the Predictive Modelling of Production Paths and the Properties of Aluminum-Based End-Products

The processing-path vectors that describe industrial processes usually consist of a few hundreds of components. Therefore, the modelling of the end-product’s properties with such multi-component processing-path vectors is costly and often lacks sufficient accuracy for industrial applications. A possible solution is to replace such complex processing paths with the much simpler, but properly selected, mathematical structures called descriptors. In the multicomponent vector space used in this work, the descriptor is the distance between the vector of the selected and the vector of the average processing path. The next step in finding a correlation between the processing paths and the set of properties as pairs of events, and vice-versa, is to calculate the conditional probabilities of all the available pairs, either taken from regular production and/or virtually generated. This conditional or posterior probability is actually the probability that the vector of the processing path $$ \overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}}{pp}_{i} $$ will result in a set of properties given by the appropriate vector $$ \overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {P}_{i} $$ if the processing path is realized. The predictor, $$ \varvec{PRED}\left( {\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}}{pp}_{i} ,\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {P}_{i} ,\varvec{\pi}_{i} } \right) $$, the tool used in this study, is a triplet of data giving the probability $$ \varvec{\pi}_{i} $$ that the processing path $$ \overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}}{pp}_{i} $$ will result in a particular set of properties $$ \overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}}{ P}_{i} $$. Finally, to find a sufficiently strong relationship between the processing paths and the set of properties, or vice-versa, it is necessary to recognize and select only those triplets (i.e., predictors), from all those possible, that have a probability of achieving higher than that required in the model, $$ P_{required} $$, (usually higher than 95%). The algorithm was validated by predicting the properties of randomly selected samples taken from the 150 different technological paths of the standard alloy AA 6110, and vice-versa, by predicting the chemical composition of the samples with known mechanical propertiesMechanical properties. Typically, for the standard alloy AA 6110, the following quality of prediction was achieved: $$ Precision = approx. 90\% $$$$ Recall = approx. 65\% $$$$ F - Measure = approx. 75\% $$

Varužan Kevorkijan

Effect of Extrusion Parameters on Microstructural and Mechanical Properties of EN AW 6063

ExtrusionExtrusion is a plastic formingForming process that uses cylinder shaped raw materials. Direct extrusionExtrusion method which is one of the two extrusionExtrusion types, manufactures products by forcing billets with a ram throughout the dies. By the effect of high deformation amount and elevated temperature products called profiles acquire their final properties. ExtrusionExtrusion parameters can be classified into two main topics as temperature and deformation based and these parameters highly affects the final properties of extruded products. With this concept, effect of extrusionExtrusion speed and billet heating temperature on properties of EN AW 6063 alloy were investigated in this study. Precise characterization techniques were utilized to evaluate microstructural and mechanical propertiesMechanical properties of the samples. Additionally, computer aided simulation software called QFormQForm was used for simulation of extrusionExtrusion process and final material properties and outputs of software were compared with experimental results.

Mehmet Buğra Güner, Cem Mehmetalioğlu, Osman Halil Çelik, Murat Konar, Görkem Özçelik

Simulation Study on Equal Channel Right Angular Extrusion Process of Aluminum Alloy 6061

Simulation of aluminum alloy 6061Aluminum alloy 6061 equal channel right angle extrusionEqual channel right angle extrusion is performed by using Deform-3D finite element software. The microstructureMicrostructure changes before and after extrusionExtrusion deformation is investigated through experiment corresponding to simulation working condition. The results show that the uniformity of the deformation process is affected by the factors such as friction coefficient and extrusionExtrusion paths. The single-pass extruded specimens show a lot of long banded structures along the shear direction. After the first extrusionExtrusion, the sample rotates 90° along the axis for the second extrusionExtrusion along the same path, and the grain refinement and distribution uniformity are enhanced. The suitable friction coefficient is beneficial to the accumulation of equivalent strain value. The grain is elongated along the extrusionExtrusion direction during deformation and the elongated direction is affected by the friction factors. The Angle between the elongated direction and the friction surface is from 0 to 45°.

Wenhuan Jiang, Liangying Wen, Huan Yang, Mengjun Hu, Meilong Hu, Jiahuan Jiang, Paul K.-L. Song

Characterization of Dynamic Material Property of AlSi10 Mg Aluminum Alloy Under High Strain Rate Compressive Loading

The aim of this paper is to characterize the dynamic material property of the aluminumAluminum alloy, AlSi10 Mg under high strain rateStrain rate compressive loading. From literature reviews, it was found that the characteristic of dynamic deformationDynamic deformation behaviors of aluminumAluminum alloys under both compressive and tensile loading conditions by using split Hopkinson pressure bar techniques were different. In this work, we performed experiments at high strain rateStrain rate compressive loadings on selective laser melted (SLM) samples with a split Hopkinson pressure bar. The samples were produced at five different layer orientations, such as 0°, 30°, 45°, 60°, and 90° with three different global energy density (GED) values. The GED value of a sample is related to laser power, scan speed, hatch spacing, and layer thickness of the SLM process. In our study, we found the characteristic material deformation behavior depends on building layer orientations and the GED values.

Md Salah Uddin, Kristofer Kuelper, Brahmananda Pramanik

Current Efficiency for Direct Production of an Aluminium–Titanium Alloy by Electrolysis in a Laboratory Cell

The electrochemical production of an aluminiumAluminium -titanium alloy in situ during aluminiumAluminium reduction in fluoride-based melts was investigated. Experiments were carried out in a laboratory cell at 0.9 A/cm2 and temperatures 960 and 970 °C. TiO2 was added as a raw material along with alumina. Bath samples were collected regularly and analyzed with ICP-MS to estimate the co-deposition rate of titanium during the experiment. Apparent current efficiencies were recorded, and analysis of deposit was carried out by ICP-MS to complete the material balance and calculate the real current efficiencies. The content of titanium was varied up to 1 wt% and alumina concentration in the bath was below saturation.

Omar Awayssa, Rauan Meirbekova, Gudrun Saevarsdottir, Gudjon Atli Audunsson, Geir Martin Haarberg

Corrosion Inhibition Effect of Aloe Saponaria Gel on the Corrosion Resistance of Aluminum

The most effective and efficient corrosion inhibitors are organic compounds that have pi bonds, heteroatoms (P, S, N and O), and inorganic compounds, such as chromates, dichromates, nitrites and so on. However, the use of these compounds has been questioned lately, due to the negative effects they cause in the environment, hence the growing interest in seeking to replace them. The inhibiting effect of Aloe SaponariaAloe Saponaria gel on the corrosion process of aluminumAluminum in an acid medium of 0.5 M HCl was analyzed. Measurements of polarization potentiodynamic, Electrochemical ImpedanceImpedance Spectroscopy and weight loss were employed, in acid medium in absence and presence of the inhibitor, at different concentrations (10, 20, 30% v/v), at the following temperatures: 293, 308, 315 and 323 K. The results obtained in the different concentrations show an increase in the efficiency of the inhibitor effect at 293 K.

Malena Soledad Friedrich, Alicia Esther Ares, Claudia Marcela Méndez

Experimental Investigation of MgAl2O4 Spinel Formation in Oxidation of Al–Mg Alloys

Formation of MgAl2O4-spinelSpinel in oxidationOxidation of Al–Mg alloys containing a range of Mg content from 0.5 to 5 mass% was experimentally investigated and compared with that in phase diagrams with O2 partial pressure. The relation between oxidationOxidation kinetics and β-Al3Mg2 fraction was examined based on cross-sectional surface observation after oxidationOxidation under a harsh condition and Scheil-Gulliver cooling calculation. With increasing Mg content up to 5 mass% from 2.5 mass%, the fraction of β-Al3Mg2 phase significantly increased. According to the phase diagramPhase diagram with O2 partial pressure at 500 °C calculated by FactSage 7.1, the oxide that first appeared was MgOMgO, the most favourable reaction product in this system. After the MgOMgO formation, the concentration in the surrounding area would become relatively Mg-poor and consequently, MgAl2O4-spinelSpinel was possibly formed as secondary oxide. Continuous consumption of Mg to form MgOMgO and spinelSpinel would cause a further reduction of Mg concentration in the residue and then, lead to Al2O3 formation. As a result of cross-sectional surface observation by scanning electron microscopy, both Mg-rich and Mg-poor areas on the surface of Al-5 mass% Mg alloy sample after oxidationOxidation at 500 °C for 24 h under an ambient atmosphere were found.

Young-Ok Yoon, Seong-Ho Ha, Bong-Hwan Kim, Hyun-Kyu Lim, Shae K. Kim

Impact of Dispersion Hardening by Alumina Nano Particles on Mechanical Properties of Al 1100

The paper presents a study on the effect of adding a small amount of particles to a technically pure aluminumAluminum alloy on its structureStructure and mechanical propertiesMechanical properties. For this purpose laboratory castings of Al 1100 alloy with the addition of 0.5 and 1.0 wt% Al2O3 were produced. The introduction of master alloys containing particles into the melt was accompanied by ultrasonic treatment. Images of the structureStructure of the alloys obtained showed that ultrasonic treatment contributes to producing a material with zero porosity; this fact is also confirmed by the measurement of density which values are close to the theoretical ones. Analysis of mechanical propertiesMechanical properties revealed that the conditional yield strength, tensile strength and hardness of the nanocomposite with a metal matrix Al 1100/wt. nano Al2O3 were prone to increase with increasing the percentage of aluminumAluminum oxide in the matrix alloy while reducing the plasticity. This behavior of studied alloys reinforced with nanoparticles is a consequence of refining the grain structureStructure of the material during crystallization due to the presence of particles acting as inoculants.

Ilya Zhukov, Alexander Kozulin, Anton Khrustalev, Evgeny Moskvichev, Alexander Vorozhtsov, Dmitry Lychagin

Investigation of Temperature Variation During Friction Drilling of 6082 and 7075 Al-Alloys

Friction drillingFriction drilling is used to process special holes with a bushing and a boss in thin sheet metals without producing chips via a non-traditional tool-drill. Friction drillingFriction drilling parameters involve the feed rate, rotational speed and profile dimensions of the drilling tool, which directly affect the induced bushings dimensions, as well as, the microstructureMicrostructure of the produced hole. In the present study, friction drillingFriction drilling parameters were manipulated during the performance of friction drillingFriction drilling of 6082 and 7075 Al-alloys, moreover, the temperature variation in the tool-work-piece interface was recorded during the drilling processes via an infrared camera and four thermocouples located at different positions near the drilling zone. During the formation of the bushing and the boss in the investigated aluminumAluminum sheet metals, the minimum measured temperature was 220 °C and the maximum measured temperature was 380 °C. It was found that the temperature in the tool-work-piece interface increased with the reduction of the feed rates and the increase of both of the rotating speeds and the tool cone angles. Furthermore, the surface roughnessSurface roughness values of the drilled holes were found to be increased with the increase of the rotational speeds.

Nadia Hamzawy, Mahmoud Khedr, Tamer S. Mahmoud, Iman EI-Mahallawi, Tarek A. Khalifa

Study on the Anti-EMF of Al-Er Master Alloy Prepared by Er2O3 as Erbium Source

Al-Er master alloyAl-Er master alloy is an excellent refining agent, which can improve the recrystallization temperature of Al alloy. At 750 °C, Al-Er alloy is prepared by electrodeposition in molten KF (25 wt%)-LiF (20 wt%)-ErF3 (10 wt%)-KCl (45 wt%) system with Er2O3Er2O3 as the source of Er, the sinking Al liquid as cathode, and the anti-EMFAnti-EMF is studied. The results show that under the condition of 16 A/dm2, the anti-EMFAnti-EMF increases first and then stabilizes with the increase of electrolysis time. After adding Er2O3Er2O3 (2 wt%), the anti-EMFAnti-EMF drops by 0.19 V on average, and the feeding period measured is 6 min. Finally, when 750 °C, the electrolysis time is 24 min, and the current density is 12 A/dm2, the Er concentration in alloys reached the maximum of 3.65%, and the current efficiencyCurrent efficiency reached 74.64%. By XRD and SEM characterization, alloy components are mainly Al3Er, and few of Al12Er. The phase of Al-Er alloy distribution is more uniform.

Hongguang Kang, Jidong Li, Chaogang Zhang, Qian Wang, Yiyong Wang, Zhe Ning, Jilin Lu, Jing Li

Aluminum Reduction Technology

Frontmatter

Comparison Between Different Laminated Aluminum Busbars Expansion Joints in Terms of Mechanical Performance and Relative Costs

Laminated aluminumAluminum expansion joints are an integral part of any busbar system and are commonly used in potline and substation DC circuits. These elements not only transfer electrical current from one rigid conductor to the next, but also deform to absorb thermal expansion in a controlled manner, therefore avoiding the generation of excessive thermomechanical stresses elsewhere in the system. Different geometries and construction techniques have been proposed throughout the years to accomplish a given specific task, such as accommodating longitudinal displacements from long conductors, for instance. It was found that, in practice, different designs respond differently to combinations of axial and transverse displacements. The objective of this work is to compare different laminated aluminumAluminum busbars expansion joints in terms of their capacity to accept imposed displacements as well as fabrication and installation costsFabrication and Installation Costs. Three distinct topologies were assessed by means of both empirical testing and numerical modeling and the different findings are discussed. Recommendations are made for further developments.

André Felipe Schneider, Daniel Richard, David Leroux, Olivier Charette, Francis Quintal

Demo Retrofit Study of a Chinese Inspired Cell Technology

For many years, the authors have been demonstrating their cell modeling tools and cell retrofit skills using those modeling tools to present demonstration cell retrofit studies. One recent series of cell retrofit studies leads to the presentation of a cell design predicted to be able to operate at 10 kWh/kg of Al. The authors now embark on a new demonstration retrofit study this time using a Chinese cell technology inspired base case as a starting point. There are plenty of public domain information on Chinese cell technology: potshell, busbar and lining design, so that Chinese cell technology inspired base case cell design is quite similar to existing Chinese cell technologies. This first retrofit study aims at demonstrating the huge potential of productivity increase that those existing Chinese cell technologies represent without compromising the power efficiency.

Marc Dupuis, Valdis Bojarevics

Mass Transport by Waves on the Bath Metal Interface in Electrolysis Cell

The movement of waves on the surface of a fluid is always accompanied by a displacement of the fluid particles in the waveWave propagation direction, this is called the Stokes driftStokes drift. This phenomenon can be found in aluminum electrolysisAluminum electrolysis cells. More or less regular oscillations animate the interface between the electrolyte bath and the metal in a cell. It is well known that material, such as rafts of undissolved aluminaAlumina and solidified bath and cryolite snow can float on the metal-bath interface. So these objects can be transported by waves on the interface. The purpose of this paper is to review the literature on the works already done about the surface waves, interface waves and Stokes driftStokes drift. Then the mass transport induced by these waves will be estimated for the case of the metal bath interface in the electrolysis cells.

L. Rakotondramanana, L. I. Kiss, S. Poncsák, S. Guérard, J.-F. Bilodeau

Numerical Investigation of Flow Field Effect on Ledge Shape in Aluminum Reduction Cell by Coupled Thermo-Flow Model

A coupled thermo-flow modelCoupled thermo-flow model was developed to calculate the three-dimensional ledge in a 400 kA aluminum reduction cellAluminum Reduction Cell. The results show that the three-dimensional ledge and shell temperature have a good agreement with the industrial test values. The mechanism of flow field influencing the ledge shape was proposed. Based on this model, a reverse flow experiment was designed to analyze the effect of electromagnetic forceElectromagnetic force on ledge shape. Moreover, the effect of anode gas on ledge profile was discussed.

Hongliang Zhang, Qiyu Wang, Shuai Yang, Jie Li, Jinding Liang, Ling Ran

Study of Heat Distribution Due to ACD Variations for Anode Setting

The carbon anodes in a Hall-Héroult cellHall-Héroult cell are continuously consumed and thus require periodic replacement. During the setting of a cold new anode, bath freezes around it, causing the anode current flow to be impeded and redistributed to the other anodes. The anode settingAnode setting event introduces significant disturbances which affects cell stability and thermal balance. Common work practices, such as anode beam raising, affect the bath temperature in the entire cell, even for regions far away from where the anodes will be set. With measurements of anode current distribution, control strategies for anode settingAnode setting can be optimized and improved, for example by preheating the region where anodes will be set. In this paper, the effects of raising groups of anodes on the distribution of bath temperature is investigated. The results show that heat generation can be targeted to specific regions in the bath, as well as to minimize the unwanted effect on ledge profile. Additionally, contrary to simple intuition, raising anodes in a particular bath region is shown to have a greater effect on other bath regions.

Choon-Jie Wong, Yuchen Yao, Jie Bao, Maria Skyllas-Kazacos, Barry J. Welch, Ali Jassim

Anodic Incident Detection through Multivariate Analysis of Individual Anode Current Signals

Anodic incidentsAnodic incident occurLaJambe, David when an aluminumPoulin, Éric electrolysisDuchesne, Carl cell short circuits at a specific anode position as a result of a spikeSpike or other deformation forming on the bottom surface of the anode. These undesirable process events reduce the current efficiency of the affected cell, which makes early detection critical for minimizingTessier, Jayson losses. This paper describes the development of an anodic incidentAnodic incident detection system based on monitoring individual anode currentAnode current signals with a multivariate Principal Component Analysis (PCA)Principal Component Analysis (PCA) model. The model and monitoring system were developed and tested using 2422 individual anode currentAnode current signals collected from an aluminum smelter. The results indicate that anode currentAnode current signals may be useful for detecting anodic incidentsAnodic incident in advance relative to regular detection methods based on typical process signals. Anodic incidentsAnodic incident appear to alter the correlation structure of individual anode currentAnode current signals, which could make detection possible by monitoring the Squared Prediction Error (SPE) statistic.

David LaJambe, Éric Poulin, Carl Duchesne, Jayson Tessier

Fault Detection and Diagnosis of Alumina Feeding System Using Individual Anode Current Measurement

With the growth in sizes of the Hall-Héroult cells, the detection and diagnosis of faults in the Hall-Héroult processHall-Héroult process is becoming more difficult, as the information from the cell resistance, which is obtained from the line current and cell voltage, only indicates overall conditions of the cell. In order to achieve improved process efficiencyEfficiency, the measurement of individual anode currentIndividual anode current has been studied extensively in recent years. Unlike conventionally measured line current and cell voltage, individual anode currents provide information about the localized cell conditions. This paper presents a method to detect faults in the aluminaAlumina feedingFeeding system in the Hall-Héroult cells from individual anode currentIndividual anode current measurement. It involves the dynamic estimation of the feedingFeeding system operating conditions by incorporating a mass balance model, without using physical sensors attached to the feeders. This method is shown to be effective in observing feeder failure, evaluating the seriousness of the fault and identifying failed feeder location.

Yuchen Yao, Jie Bao, Maria Skyllas-Kazacos, Barry J. Welch, Ali Jassim

Change of Anode Operation Pattern from Single to Double Staircase at Albras

Most essential operational procedures in prebaked cells are performed with cranes in Albras, which leads to high usage and dependence of these equipments, making it difficult to handle possible failures. The old anode change pattern was single staircase, where anodes were replaced one at a time. Aiming to improve logistics and reduce crane time usage, Albras has tested a new anode operation strategy, where two anodes are changed per cell at the same time, running a not standard sequence during the transition period. Due to expected pot instability increase, several parameters as bath generation, temperature, noise and anode effectAnode effect were tracked to evaluate process impactsProcess Impacts. Anode current pick up and current distribution measurement were also analyzed together with time of activity, comparing cells in single and in double anode changeDouble anode change strategy. This paper also discusses further strategies to keep cells in double anode pattern more stable after anode change operation.

Camila R. Silva, Vanderlei O. Fernandes, Nilton F. Nagem, Ivar E. V. Sousa

An Advanced Nonlinear Control Approach for Aluminum Reduction Process

With the increase in amperage and associated reduction of electrolyte volume to anode surface ratio, the existing cell controlCell Control method is facing more challenges due to greater variability in process conditions spatially and temporally. Therefore, it is beneficial to develop advanced control strategies that can achieve a more balanced cell with even distribution of, e.g., aluminaAlumina concentration and individual anode currentIndividual anode current, and hence improve energy efficiencyEfficiency and reduce greenhouse gas emission. In this paper, an advanced nonlinear control approach is developed, which determines the optimal local control actions based on the measurements including the individual anode currentIndividual anode current and cell voltage. This new approach is flexible as it can optimize the control action to achieve different cell performance targets. This work illustrates the effectiveness of the proposed control with an example of improving the current efficiencyCurrent efficiency. Also, different performance targets are discussed, which provide the potential for the proposed control method to have optimal control targets for best cell efficiencyEfficiency.

Jing Shi, Yuchen Yao, Jie Bao, Maria Skyllas-Kazacos, Barry J. Welch, Ali Jassim

Model Based Approach for Online Monitoring of Aluminum Production Process

In Hall-Heroult processDa Silva Moreira, Lucas José for aluminium production, Besançon, Gildas estimating theFerrante, Francesco alumina concentration andFiacchini, Mirko the anode-cathodeRoustan, Hervé distance (ACD) remains a challenge. One of the difficulties arises from the fact that it is not possible to measure those quantities continuously during the pot operation. This article presents a novel approach for an online estimating alumina concentration and ACD in a regular aluminum-reduction pot cell using a Linear Kalman FilterKalman filter. This is done by using an appropriate dynamical model for the pot, which is obtained by combining the first principle modeling and experimental identification of alumina concentration behavior from irregularly sampled data. Moreover, a dynamical model for the pot resistance is identified as a function of the alumina concentration and ACD data. The proposed approach is validated on an industrial platform.

Lucas José da Silva Moreira, Gildas Besançon, Francesco Ferrante, Mirko Fiacchini, Hervé Roustan

Predictive Analytics for Enhancing Productivity of Reduction Cells

With increasing energy prices and lower LME, aluminumAluminum smelters across the globe are focusing on reducing specific energy consumption. Increasing current efficiencyCurrent efficiency (CE) not only reduces energy but also increases productivity. Since, early 1990s, fundamental studies and lab-scale experiments have provided insights on CE and its dependence on process parametersProcess parameters, however these were based on ideal conditions and actual plant data should also be considered. This article presents a predictive modelPredictive model for CE utilizing machine learningMachine learning algorithm (random forest regressor) on 360 kA pot-line data. The model helps in identifying the optimal parameter range to maximize CE of individual pot. Results are compared with fundamental and lab-scale experiments published in literature, showing good agreement in most cases along with few insights. Impact of parameters such as cathode drop, bath height, composition, etc. has been discussed.

Shanmukh Rajgire, Abhijeet Vichare, Amit Gupta, Devendra Pathe

Restart of Shutdown Pots: Troubles, Solutions and Comparison with Normal Pots to Improve Results

It is recognized that the premature failure of the pots is a big challenge and worked on the projects to do sidelining and repairing of the shutdown pots to restart. This “Pioneering Work” was carried out at Hindalco Industries Limited, Renukoot, which is recognized as a worldwide leader in this field of AluminiumAluminium Production. This paper provides failure analysis of low amperage Hall-Heroult cell and an overview of the sidelined pot. It provides method of sidelining, cathode change, baking, and performance of sideline pots. The paper also makes comparisons for new pots of same life with the sidelined pots, benefits and way forwards. One of the main objectives of this project is the comparison of the sidelined pot with normal pots. The present work is a part of the project “Side-Lining of low amperage Hall-Héroult cellHall-Héroult cell”. The experiments were performed in some selected pots to observe and analyze the parameters like baking conditions, cell noise, cell voltage and cathode lining drop.

Ved Prakash Rai, Vibhav Upadhyay

Electrochemical Behaviour of Cu-Al Oxygen-Evolving Anodes in Low-Temperature Fluoride Melts and Suspensions

Cu-based alloys have been considered as promising candidates (along with the Fe-Ni alloys) for the inert anodes material in aluminiumAluminium reduction cells with low-temperature electrolytes. However, low purity of aluminiumAluminium due to the contamination by anode corrosionCorrosion products is a problem yet to be solved. Introduction of alumina suspensionAlumina suspension as an electrolyte has been presented recently as a possible solution for providing commercial purity aluminiumAluminium produced with the metallic anode. An attempt to characterize the CuAl-based anodes electrochemical performance in KF-AlF3KF-AlF3-Al2O3 melts and suspensions has been made and presented. The effects of the suspensionSuspension (or melt) properties, the anode composition and the temperature on the electrochemical behaviour of the anode and the kineticsKinetics of the oxide layer formation during polarization are studied. The 90Cu-10Al anode in the KF-AlF3KF-AlF3-Al2O3 suspensionSuspension with the cryolite ratio 1.3 and the dispersed phase volume fraction not more than 0.12 is found to be the good option for further investigations.

Andrey S. Yasinskiy, Sai Krishna Padamata, Peter V. Polyakov, Aleksandr S. Samoilo, Andrey V. Suzdaltsev, Andrey Yu. Nikolaev

Alumina Concentration Measurements in Cryolite Melts

The alumina dissolutionAlumina dissolution is one of the most important processes for advanced aluminiumAluminium electrolysis. For a better understanding and improvements on the dissolution process, it is important to find an effective and reliable method to perform in situ measurements in the cryolite melt, obtaining in this way the variation in aluminaAlumina concentration during the entire electrolysis process. Electromotive force (emf) measurements between an electrochemical aluminaAlumina sensor made of graphite and two reference electrodes (a graphite quasi-reference electrode and an aluminiumAluminium reference electrode), were performed during the addition of aluminaAlumina and throughout the entire process of dissolution. Cell reactions between the aluminaAlumina sensor and the two reference electrodes were derived, and the theoretical cell voltages were calculated. The cell voltage measurements were analyzed and compared with the theoretical calculations to determine the reliability of the electrochemical sensor and verify the validity of the basis and assumptions used in this work for the determination of aluminaAlumina concentration.

Luis Bracamonte, Karoline Nilsen, Christian Rosenkilde, Espen Sandnes

The Influence of Polarisation on the Wetting of Graphite in Cryolite-Alumina Melts

The wetting properties of graphiteGraphite were measured with the immersion/emersion technique in a high temperature aluminaAlumina reductionReduction cell. The wetting was measured at untreated, polarised and anode effectAnode effect polarised samples. Most measurements were made in melts with 1 wt% aluminaAlumina, although some measurements were performed at higher aluminaAlumina content. As long as passivation (i.e. anode effect) was not initiated polarisation improved the wettability significantly and the wetting increased with increased polarisation. AnodesAnode polarised to anode effect exhibited consistently very poor wetting. Most of the decrease in wetting occurred during the first few seconds of the anode effectAnode effect, with full de-wetting from about 60 s.

Henrik Åsheim, Ingrid A. Eidsvaag, Asbjørn Solheim, Henrik Gudbrandsen, Geir M. Haarberg, Espen Sandnes

Oxidation Study of Zinc Sulfite on the Removal of Sulfur Dioxide from Aluminum Electrolysis Flue Gas by Zinc Oxide

As the high sulfur petroleum coke consumption gradually increase in the production of pre-baked anode, SO2 is produced higher than the new environmental protection standard at the process of aluminum electrolysisAluminum electrolysis . Aiming at this problem, zinc oxide desulfurizationDesulfurization process is put forward to remove low concentration SO2 and zinc sulfate heptahydrate is obtained as the final desulfurizationDesulfurization product in this paper. The effects of the concentration of zinc sulfiteZinc sulfite , initial pH value, temperature, stirring speed and gas flow rate on the oxidationOxidation rate of zinc sulfiteZinc sulfite oxidationOxidation were investigated by orthogonal experiment. The results showed that the stirring speed was the greatest effect on the oxidationOxidation rate of zinc sulfiteZinc sulfite , followed by the initial pH value, the gas flow rate, the temperature and the initial concentration of zinc sulfiteZinc sulfite . The optimal experimental conditions were 1% of zinc sulfiteZinc sulfite , initial pH 3, temperature 30 °C, oxygen flow rate 0.5 L/min, and stirring speed 360 r/min.

Xuejiao Cao, Ting-an Zhang, Yan Liu, Weiguang Zhang, Simin Li

Electrolysis of Low-temperature Suspensions: An Update

Among different “novel” technologies for eco–friendly aluminiumAluminium production with zero greenhouse gas emissionsGreenhouse gas emissions, the electrolysis of alumina suspensionAlumina suspension (or slurrySlurry) based on halide melts deserves more attention than it got recently. The original idea of the slurrySlurry was first proposed by Theodor R. Beck and has been modified and developed basically by Petr V. Polyakov. This paper presents a comprehensive analysis of the current status of this technology, future opportunities, and the new experimental results, which have not been published yet. This overview covers the properties of high-temperature suspensions, including sedimentationSedimentation behaviour and apparent electrical conductivity; anodic process on oxygen-evolving electrodes, including the polarization characteristics and the bubble behaviour at vertical anodes; cathodic process on wettable substrates; primary electrolysis results; and the general considerations touching upon the possible cell designs and the thermal balance. The future scope of the technology and possible applications are discussed.

Andrey Yasinskiy, Andrey Suzdaltsev, Sai Krishna Padamata, Petr Polyakov, Yuriy Zaikov

Adapting Modern Industrial Operation Parameters in a Standardized Laboratory Cell for Measuring Current Efficiency for Aluminium Deposition: Unexpected Challenges and Lessons Learned

“Current efficiencyCurrent efficiency” is an important cell parameter which shows how efficiently current is used to produce aluminiumAluminium. Operational parameters that affect current efficiencyCurrent efficiency have been widely studied in the aluminium industryAluminium Industry, and factors like electrolyte composition and superheat have been changed to improve the current efficiencyCurrent efficiency. However, the industrial cell is a complex system where all parameters are closely interrelated, which makes it difficult to change any parameter independently. Sterten and Solli developed a laboratory cell specifically designed to study current efficiencyCurrent efficiency. Many studies have been made using the cell to study the effect of various operational parameters on current efficiencyCurrent efficiency. As a result of improved understanding, the operational parameters presently used by the industry have changed, which is reflected by new operating condition standards for the laboratory cell. This study focuses on the challenges faced when implementing new standards in the current efficiencyCurrent efficiency laboratory cell; these standards (11.5% AlF3, 5% CaF2, 4% Al2O3, cryolite ratio 2.2, temperature 965 °C) are comparable to typical parameters in the aluminium industryAluminium Industry today.

R. Meirbekova, O. Awayssa, G. M. Haarberg, G. Saevarsdottir

Aluminium Smelter Crust—Phase Distribution and Structure Analysis of Top Zone Layer

Anode cover materialAnode cover material (ACM) partly fuses at the bottom where it interacts with anode and bath in the aluminiumAluminium reduction cell. This consolidated material is defined as the top crustCrust in the cell, and plays a crucial role in maintaining heat balance, protecting the carbon anode from air-burning and absorbing the fluorides evaporation in the cells. Previous studies have been conducted to illustrate the crustCrust formation and properties. However, there is rarely a systematic structural analysis of crustCrust in the vertical direction due to the complexity and inhomogeneity of industrial crustCrust . In the present study, the phase composition of crustCrust was systematically analysed in the vertical direction, and five zones were identified based on the phase composition. Furthermore, two types of particles are identified in top zone (1) namely: smelter grade aluminaAlumina (SGA) and crushed bath particles (CBPs). A systematic analysis on CBPs have shown four types of structural features.

Shanghai Wei, Jingjing Liu, George Allan, Tania Groutso, John J. J. Chen, Mark P. Taylor

Influence of Anode Cover Material Particle Size Composition on Its Physical Property and Insulation Performance

Main physical propertyPhysical property and service performance on aluminum electrolysisAluminum electrolysis cell of five groups anode cover materials with different particle composition was examined. The results showed that with the decrease of particle sizeParticle size, bulk density increased from 1.56 to 1.62 g/cm3 and then decreased to 1.52 g/cm3, and repose angle decreased from 41.2° to 38.3°. On the whole thermal conductivity at working temperature decreased as particle sizeParticle size decreased, it decreased from 1.21 to 0.91 W/m K and then decreased slowly. Covering material surface average heat dissipation decreased when used on cell as particle sizeParticle size decreased, when particle sizeParticle size of covering material reduced to a certain extent, covering material surface average heat dissipation decreased to 2100–2200 W/m2, continuing decreasing particle sizeParticle size, no obvious insulationInsulation improving was got. Through the study, one cover materials was choen, and it particle composition was: <0.25 mm 29.85%, 0.25–2 mm 30.29%, 2–8 mm 29.65%, and >8 mm 10.21%.

Changlin Li, Junqing Wang, Yunfeng Zhou, Bin Fang, Yanfang Wang, Qingguo Jiao

Lab Scale Experiments on Alumina Raft Formation

During feeding of aluminaGylver, Sindre Engzelius into a Hall-Héroult cell,Solheim, Asbjørn raftsRafts floatingGudbrandsen, Henrik on the bathFollo, Åste Hegglid surfaceEinarsrud, Kristian Etienne may be formed. In this study, rafts were created in a laboratory furnace by adding 4 g secondary alumina in industrial bath. Samples were withdrawn from the bath in a time interval between 30 and 300 s. The experiments show that at 970 $$^\circ $$C, raftsRafts will be formed within 30 s, and then slowly dissolve again with a constant rate of 0.8 g/min. Pores were found in the samples, giving extra buoyancy to the raftRafts, thus increasing the floating time. Same experimental setup was used to investigate the effect of preheating of alumina, where it was found that coherent raftsRafts will form up to at least 500 $$^\circ \mathrm{C}$$.

Sindre Engzelius Gylver, Asbjørn Solheim, Henrik Gudbrandsen, Åste Hegglid Follo, Kristian Etienne Einarsrud

Mass- and Heat Transfer During Dissolution of Alumina

Dissolution of aluminaAlumina in industrial aluminiumAluminium cells is a complicated process, not least because it involves formation of agglomerates, and it involves mass- and heat transferHeat transfer phenomena taking place simultaneously. In the present study, the diffusion coefficientDiffusion coefficient of aluminaAlumina in cryolitic melts was measured using a rotating aluminaAlumina disc. It was found that the temperature dependence of the diffusion coefficientDiffusion coefficient is relatively large. The enthalpies for heating of aluminaAlumina, conversion, and dissolution are summarised. The addition of 1 wt% aluminaAlumina causes adiabatic cooling of typically 10–12 °C in a normal industrial bath. The dissolution can be regarded as being purely mass transferMass transfer controlled, since the heat required for dissolution only brings about 1 °C temperature drop from the bath bulk to the aluminaAlumina surface. The bath at the aluminaAlumina surface is saturated in aluminaAlumina and has a lower liquidus temperature than the bulk. Alumina dissolutionAlumina dissolution can, therefore, take place in a supercooled bath.

Asbjørn Solheim, Egil Skybakmoen

The Rate of HF Formation During Addition of Alumina to NaF-AlF3 Melts

A major contributor to HF gas evolution during aluminiumAluminium electrolysis is the hydrolysisHydrolysis of aluminaAlumina water. The objectives of this work were to investigate the kineticsKinetics of HF generation, and how water residence time in the atmosphereAtmosphere above the bath influences the HF formationHF formation. The HF concentration in the off-gas was measured during additions of aluminaAlumina to a NaF-AlF3 melt (r = 2.2). The aluminaAlumina water release rate upon rapid heating was also measured separately when aluminaAlumina was added to a hot empty quartz cell. In the melt experiments, the residence time of the aluminaAlumina water was varied by changing the nitrogen gas flow rate through the experimental reactor. The HF formationHF formation occurred instantly and the rate determining step is the aluminaAlumina water release rate. For the range in this study, there was no effect of residence time of the gas in the reaction chamber on the amount of HF formed.

Karen S. Osen, Dian Mughni Fellicia, Christian Rosenkilde, Camilla Sommerseth, Ole Kjos

Validation of the Gravimetric Method to Properly Follow Alumina Dissolution in Cryolitic Bath

Alumina dissolutionAlumina dissolution is now one of the greatest concerns about Hall-Héroult processHall-Héroult process optimization. To tackle alumina dissolutionAlumina dissolution kineticsKinetics, a gravimetric methodGravimetric method was developed. This method follows the apparent weight of an aluminaAlumina sample while immersed in a cryolitic bath. Then, from the weight over time curve, it is possible to identify the forces acting on the sample especially the change of gravity and buoyancy forces. The experimental results obtained by this method were compared to four other values: namely the data found in the literature, values computed with a CFD model, the total mass loss of aluminaAlumina disc samples over time and finally to a sample boundary displacement method. The boundary displacement and the CFD model have also demonstrated the strong dependence of the dissolution rate on the convection pattern around the sample.

Jonathan Alarie, Thomas Roger, László I. Kiss, Sándor Poncsák, Sébastien Guérard, Jean-François Bilodeau

Development of a Mathematical Model to Simulate Raft Formation

The aluminumAluminum industry searches to improve the incorporation of the aluminaAlumina into the electrolyte bath. This paper presents the development of a model to simulate the flow of aluminaAlumina particles with the thermal exchange between the particles and the liquid. The first part of the model focuses on the interaction between spherical particles and their environment using the Discrete Element MethodDiscrete Element Method. The second part uses the equations of the Smoothed Particle Hydrodynamics to simulate the thermal exchange between the particles themselves and with the liquid. The thermal sub-model includes the phase change to integrate the raft formation with the solidification of the bath. To validate the thermal sub-model, a low temperature model and schlieren imaging was used. This method consists to observe a thermally disturbed area with the refraction of light. The experimental study involved the injection of organic particles into the water. The particles were previously cooled with liquid nitrogen. Finally, some thermal tuning factors are settled to adjust the calculated thermally disturbed area to the results of the visualization. A high-speed camera was used to study different injection methods and the results were compared to the simulations to validate the model.

T. Roger, K. Fraser, L. Kiss, S. Poncsák, S. Guérard, J. F. Bilodeau, G. Bonneau

Efficient Alumina Handling

The paper describes various testing procedures of powder testing and identifies new concepts of material handling from the ship to the smelter. Options are discussed and the different concepts are described. Based on extensive laboratory tests a decision matrix for materials handling is laid out. Compared to many other powderous materials, aluminaAlumina is easy to handle in terms of controlling the material flow. But segregation and attritionAttrition of the material has to be minimized. AttritionAttrition is sometimes seen as a material inherent behaviour, but it is highly influenced by the way the material is conveyed. High velocities of pneumatic conveyingConveying and direct impact has to be avoided. To reduce scalings at take off points, pressure drops have to be kept at low levels. Finally, in this paper a layout for a multipurpose aluminaAlumina terminal is described and discussed.

Jan Paepcke, Arne Hilck, Michael Altmann-Rinck, Andrej Meinhardt

Status Analysis of Particle Size Distribution and Attrition Index of the Smelter Grade Alumina

Smelter Grade AluminaAlumina (SGA) is used as the raw material in primary aluminumPrimary Aluminum electrolysis. The current aluminum reductionAluminum reduction technology has strict requirement to the particle size distributionParticle size distribution of SGA during the whole production process. This paper investigated the particle sizeParticle size parameters of industrial SGA on the Chinese market. The tested parameters include the particle size distributionParticle size distribution and the attrition indexAttrition index of 14 kinds of fresh SGA and 7 secondary SGA, respectively. The relationship between the particle size distributionParticle size distribution and the attrition indexAttrition index is discussed, and the influence of dry scrubbing system on the aluminaAlumina particle sizeParticle size is considered as well. At last, this paper tries to propose an evaluation criterion based on the combination of particle size distributionParticle size distribution and attrition indexAttrition index.

Youjian Yang, Xiaojuan Pang, Junfeng Qi, Wenju Tao, Zhaowen Wang, Fengguo Liu, Aimin Liu, Jiangyu Yu, Bingliang Gao, Zhongning Shi, Xin Shu

The Effect of Hard Scale Deposition on the Wall Heat Flux of a Cold Finger

A cylindrical cooled probe (cold-finger placed in cross-flow)Cold-finger has been used to investigate foulingFouling in the off-gas duct located upstream from the gas cleaning system during primary aluminium production. Hard scale was formed on the front side of the probe whereas loose deposits accumulated on the rear side, causing inhomogeneous foulingFouling resistance along the cold-fingerCold-finger circumference. Thermocouples and heat flux sensors allowed for the monitoring of the global and local heat transferHeat transfer on both the front and rear sides of the probe. Additionally, the off-gas velocity upstream of the probe was monitored. Regression analysis of the heat transferHeat transfer data produced was performed to calculate the foulingFouling resistances from multiple experiments. Finally scale thickness was measured after the experiments and used to estimate its thermal conductivity.

Daniel Perez Clos, Sverre Gullikstad Johnsen, Petter Nekså, Ragnhild Elizabeth Aune

The Application of Intelligent Breaking and Feeding Technology for Aluminium Reduction Pot

Reducing voltage to achieve lower energy consumption has been a constant goal for aluminiumAluminium pot linePot Line operators. However, voltage reduction could be accompanied with breaker jamBreaker jam and elephant legElephant leg, having many disadvantages. In this paper, three different breaker jamBreaker jam identification solutions have been tested based on analysis of the core parameters that have the greatest impact on breaker jamBreaker jam and elephant legElephant leg. On the foundation of site practices and experiments, a new intelligent breakingBreaking and feedingFeeding technology, which consists of following key features, has been developed: breakingBreaking in groups + single-point feedingFeeding + use pressure sensor to identify breaker jamBreaker jam + unlink breakingBreaking and feedingFeeding sequence + intelligent feedingFeeding technology + energy compensation technology. This technology has been applied to some Chinese smelters and has achieved good results. Hence, breaker jamBreaker jam and elephant legElephant leg can be reduced by 80%, breaker and cylinder life can be prolonged by 20–30% and energy consumption can be saved by 0–50kWh/t-Al.

Bo Hong, Qinghong Tian, Zhiyang Chen, Xiaotian Tan, Shiping Yu

Reducing the Carbon Footprint: Aluminium Smelting with Changing Energy Systems and the Risk of Carbon Leakage

This paper presents an analysis of the smelting trends and potential opportunities to reduce the overall greenhouse gas emissionsGreenhouse gas emissions from the primary aluminumPrimary Aluminum industry in total, both direct emissions from the production processes and indirect emissions from the electric power used. Presently, 71% of the aluminumAluminum is produced with electricity from fossil fueled power plants, and while the introduction of wind and solar generation of electricity is accelerating, these have technical constraints and limitations. On average, indirect emissions from the power used dominate as emission source, so de-carbonizing the electricity production through low-emission power sources is crucial for the primary aluminumPrimary Aluminum production in order to meet carbon emission targets. Globally the best result will be achieved by maximizing aluminumAluminum production in regions that can provide low emission power. However, national or political objectives can sometimes counter this by re-directing the use of existing hydro power used by aluminumAluminum smelters to eliminate local emissions from the process, in order to meet national goals. While this may reduce carbon emissions regionally, the result may be an increase in the industry’s global emissions through increased production capacity using non-renewable high emission level power sources in other regions. Indeed, the carbon footprintCarbon footprint of primary aluminumPrimary Aluminum production has increased significantly this century due to an increasing transition of the energy mix towards fossil based power.

Gudrun Saevarsdottir, Halvor Kvande, Barry J. Welch

Measurement System for Fugitive Emissions in Primary Aluminium Electrolysis

Fugitive emissions fromOlsen Myklebust, Håkon Aleksander Hartvedt primary aluminium productionAarhaug, Thor A. is a concernTranell, Gabriella both for occupational health and the environment. Current measuring equipment for in-situ measurements of such emissions is generally large and expensive or lacks the required time and spatial resolution to provide accurate information on the source of the emissions. This research is aimed at testing and evaluating distributed micro sensors for in-situ monitoring of dust intensity in the electrolysis hall. Multiple sensors are tested simultaneously in clusters at each location to study variation between individual sensors, giving a statistical average. These clusters are spread out in the relevant areas to map how the emission varies over both time and location based on operational activities such as anode changes. The sensor system yielded results that could be correlated to the process activities, and also showed clear variation in the fractions of PM10 and PM2.5 measured for different process operations.

Håkon Aleksander Hartvedt Olsen Myklebust, Thor A. Aarhaug, Gabriella Tranell

Validation of QCL CF4 Gas Analyzer for Sensitivity and Selectivity

Quantum cascade lasers (QCL) has open the mid-infrared (mid-IR) spectral range for laser gas monitors. For perfluorocarbonPerfluorocarbon gases (PFCs) such as CF4, continuous emission monitors are now commercially available. Since these instruments can only make use of a narrow IR band, spectral interference from other gas species is not easily resolved. In this paper a commercial QCL CF4 analyser is validated with respect to sensitivity and selectivity. In the laboratory, the laser was mounted on a 0.3-m measurement cell. A gas mixer provided humidified gas mixtures of CF4 and methane. The results indicated that while there was no interference from water in the range up to 8000 ppm H2O, a small interference from methane was observed. This was quantified to be approximately 3 ppb CF4 per ppm of methane. The sensitivity of the instrument was found to be 10.5 ppb CF4 for one-meter light path.

Thor Anders Aarhaug

A Laboratory Study of the HF Generation Potential of Particulate Fluorides from Cell Emissions

The injection type dry scrubberDry scrubber is the most commonly used technology in the aluminium smeltingAluminium smelting industry to manage HF emissions. One limitation of this technology is its sensitivity to temperature and humidity. Previous studies of smelter operation data and experimental work have demonstrated a clear link between the increase in temperature and/or humidity and increase in HF concentration in the treated off-gas at the dry scrubberDry scrubber stack. In this study, the generation of gaseous HF through a hydrolysisHydrolysis reaction between gas stream humidity and particulate fluorides has been tested under controlled laboratory conditions. The aim is to identify the HF generation potential of various particulate fluoride phases from cell emissions, and to understand the effect of temperature and humidity on the main reactive fluoride material(s). A range of particulate fluorides were tested, including purchased high purity fluorides and laboratory generated materials such as crushed bath and condensed fumeCondensed fume. Results to date show the most significant HF generation bath phase to be the condensed fumeCondensed fume phase NaAlF4NaAlF4. However, two iron fluoride phases which were minor impurities in the lab generated fume were also found to be significant HF generation contributors.

Jenny H. Hung, James B. Metson

Method Development to Estimate Total Low Voltage and High Voltage PFC Emissions

Perfluorocarbons (PFCPFC) emissions must be reported as accurate as possible. The aluminumAluminum industry is using a consistent method to estimate high voltage PFCPFC emissions. However, a new or improved method is needed to account for low voltage PFCPFC emissions. Thus, equipment sensitivity and time frequency must be revised to estimate both high and low voltage emissions, during not only anode effects above 8 volts, but also during pot disturbances that affect pot noise and therefore can make the contribution of low voltage emissions significant higher. Preliminary results showing the variability of low voltage and estimation of total PFC emissionsTotal PFC emissions is presented from recent PFCPFC measurement campaigns at two Alcoa smelters.

Luis Espinoza-Nava, Christine Dubois, Eliezer Batista

Update on SO2 Scrubbing Applied in Primary Aluminium Smelters

This paper presents an update on SO2 scrubbingSO2 Scrubbing in the primary aluminium industryAluminium Industry . Discussed is how sulfur enters the electrolysis process. It starts with calcining cokes with explanations why full desulfurizationDesulfurization during calcining is not pursued. This means the throughput of sulfur must be managed within smelter operations. To provide insight in where the sulfur goes a mass balance is presented for a generic 500 ktpa smelter. Based on this sulfur emissions can be managed with or without scrubbing. Some scenarios are discussed that don’t need scrubbing but for when scrubbing is required, an overview of the options is presented.

Stephan Broek

Optimization of a Gas Treatment Center Equipped with Extended Surface Bag Filters

The primary aluminumPrimary Aluminum industry is facing a continuous challenge of improving its environmental footprint while increasing the overall metal production at the same time. Part of this challenge can be overcome by developing a good knowledge of technologies that can optimize the performance of environmental controls. In that context, test work was performed in 2017 and 2018 on the Gas Treatment CenterGas treatment center (GTCGTC) installed at Rio Tinto’s AP60 Technology Center (AP60) located in Jonquière, Quebec, Canada. Part of the R&D initiatives of the smelter, the AP60 GTCGTC was originally provided with standard filter bagsFilter bags except for one filtrationFiltration module that was equipped with extended surface filter bagsExtended surface filter bags (ESB). After almost 5 years of operation, in 2017 the original bags were approaching the end of their useful life and presented the opportunity to consider a full conversion to ESBs. The purpose of the test work was to acquire a deep understanding about control of process parametersProcess parameters to optimize the GTCGTC performance if ESB filters would be installed in all filtrationFiltration modules. In this paper, the results of the test work are discussed.

Julie Dontigny, Stephan Broek, Philippe Martineau, Mario Dion, Raymond Emond

Update on the Abart Gas Treatment and Alumina Handling at the Karmøy Technology Pilot

During spring of 2018 Hydro started up the new ambitious Karmøy Technology Pilot (KTP) with the aim to achieve significant step changes in the specific energy consumption and at the same time define new industry standards in environmental impacts to the atmosphereAtmosphere. These goals will require energy improvements and updated improved abatement solutions for all aspects of the production including: a fully integrated updated AbartAbart gas treatment centre with dual duct systems for forced suction, anode cooling boxes with forced suction, new integrated heat exchangers, the Alfeed aluminaAlumina distribution, fluoride (AlF3) transport, and crushed bath mixing and transport. The expected “Improvements on the AbartAbart Gas Treatment and AluminaAlumina Handling at the Karmøy Technology Pilot” was presented at TMS 2018 [1]. This paper reviews the final results and experiences after reaching stable operation with even lower emissions than targeted emissions [2].

Anders Sørhuus, Sivert Ose, Eivind Holmefjord, Håvard Olsen, Bent Nilsen

The Australian Energy Crisis, Its Impact on Domestic Aluminium Smelting and Potential Solutions

Australia is facing an ongoing energy crisisEnergy crisis , driven by a combination of reduced ‘base-load’ capacity and reliability from an ageing coal-fired power station fleet, as well as the rapid uptake of variable wind and solar generation that has yet to be fully buffered by energy storageStorage . Furthermore, investment in new generating capacity and interstate grid connectivity has not kept pace with thermal power retirements. This is due to policy uncertainty around the future of high CO2 power generation, rising fuel prices, the unviability of nuclear power, and the plummeting cost of clean but variable renewable generation. The resulting national grid is proving to be susceptible to unexpected shocks and high peak spot-pricing, and is only predicted to become more volatile. Unsurprisingly, Australia’s aluminiumAluminium (Al) smelters are facing immense challenges operating in this environment. As well as potline outages occurring, smelters face an uncertain future when it comes to negotiating base-load contracts at below the cost-of-generation they have historically relied on, as the economics of base-load demand is constantly eroding and being replaced with the need to value flexible electricity consumption. This article examines some of the impacts and explores some of the pathways and opportunities that smelters can use to survive and even prosper, including power modulationModulation and the provision of ‘demand-side response’ services to the national energy grid.

David S. Wong, Geoff Matthews, Alton T. Tabereaux, Tim Buckley, Mark M. Dorreen

Recycling of the Flue Gas from Aluminium Electrolysis Cells

RecyclingRecycling of the flue gasFlue gas from aluminiumAluminium reduction cells is a possible method for increasing the CO2 concentration, thereby enabling CO2 capture. The present paper represents a preliminary study concerning some of the consequences in the electrolysis cells. The energy balance in a hypothetic 400 kA cell was estimated, and it turned out that the heat flow into the superstructure could be kept constant by decreasing the thickness of the anode cover materialAnode cover material even with a very hot gas. RecyclingRecycling gives a higher amount of collectible heat from the cells, mainly because of higher temperature in the gas entering the cell. It will be advantageous to apply catalytic burning of CO to CO2, which represents considerable extra heat. Increased sulfuric acid dewpoint may represent a challenge. It is also necessary to address the amount of hydrogen fluorideHydrogen Fluoride that re-evolves from the secondary aluminaAlumina at high superstructure temperature.

Asbjørn Solheim, Samuel Senanu

Utilization of Waste Heat for Pre-heating of Anodes

Carbon anodes are replacedGrimstad, Martin on a regular basis in Hall–Héroult cells as theyElstad, Kim Ronny are consumed by electrochemical reactions. Solheim, Asbjørn Upon insertion of new anodes, bath will freezeEinarsrud, Kristian Etienne locally as a result of low bath superheat and comparatively low anode temperature, creating an insulating layer on the anode surface, thereby delaying further production. In the current work the potential for pre-heating anodes directly utilizing waste heatWaste heat from off-gas and spent anode butts is investigated using a numerical model realized in COMSOL and industrial measurements at the Alcoa Mosjøen smelter. Anode core temperatures over 150 $$^{\circ }$$C and surface temperatures over 250 $$^{\circ }$$C were found when using butts as a direct heat source. Frozen bath samples from both pre-heated and regular anodes were collected and analysed using computer tomography (CT) in order to assess how various heating strategies influences frozen bath morphology.

Martin Grimstad, Kim Ronny Elstad, Asbjørn Solheim, Kristian Etienne Einarsrud

Toward Minimizing the of Co-evolution of PFC Emission in EGA Smelter

Primary aluminumPrimary Aluminum smelters are known to be a dominate source for the PFCPFC emission where changes in spatial condition of Hall-Héroult reduction cell would result to the co-evolution of CF4. EGA smelters have gone through various process and design upgrade programs, which resulted in allowing creeping amperage to meet production requirements. Increasing production output is usually associated with reduction in bath to amperage ratio while aiming to operate at low energy input target. Sequentially, the company has developed a special program to enhance its advance cell controlCell Control logic to allow operating at higher anode current density while maintaining low PFCPFC emission. This paper investigates major activities where the co-evolution of PFCPFC emission was detected as an anode settingAnode setting activity and condition of operating at low aluminaAlumina concentration in electrolyte. In-house developed individual anode currentIndividual anode current along with continuous monitoring of PFCPFC emission in reduction cell were deployed to validate the study.

Ali Jassim, Najeeba Al Jabri, Sergey Akhmetov, Daniel Whitfield, Barry Welch

Development and Application of GP500+ Energy Saving Aluminum Reduction Cell

AluminumAluminum smelters are always seeking opportunities to increase capacity and reduce energy consumption to survive in today’s brutal competition. At present, 500 kA level reduction cell technology becomes the mainstream technology in China. GAMI (Guiyang AluminumAluminum and MagnesiumMagnesium Design and Research Institute Co., Ltd.) has successfully developed GP500+GP500+ energy savingEnergy saving cell and the technology has been applied to the first pot linePot Line in 2017. This paper focuses on technical developments of GP500+GP500+ energy savingEnergy saving cells ranging from shell, superstructure, busbar, lining, cell controlCell Control system and remote support service. The industrial performance is also included.

Zhuojun Xie, Song He, Hongmin Ao

Cast Shop Technology

Frontmatter

Hands-Free Casting at AMAG Casting GmbH—It Is Possible!

The start-up of the aluminumAluminum rolling slab casting process is one of the most critical procedures in terms of casthouse-safetyCasthouse-Safety . In many casthouses, it is common practice that the staff works directly at the launder system and on the casting table during the whole start-up, until the steady-state phase is reached. Operators are needed along the launder system (furnaceFurnace spout control, opening of launder gates, CFF check etc.) and on the casting table (priming of the distribution bag, filling control etc.), but there are a lot of risks, which, upon materializing, can have a tremendous adverse impact on human health: wet starter-blocks, bleed-outs, hang-ups etc. can lead to very harmful situations and therefore it’s best for the operators to start the process from a safe place, away from the launder system and casting table. This paper deals with all needed mechanical and automationAutomation systems, as well as casting techniques, to enable the casthouseCasthouse staff to control the start-up at a safe place.

Bernd Prillhofer, Rudolf Dobler, Thomas Mrnik

User-Friendly Surveillance Tools to Prevent Bleed-Out During Cast Start

Cast house operation implies high risk processes related to molten metal handling like charge preparation or cast startCast start. Hydro’s R&D center Bonn has the ambition to provide procedures and user-friendly tools helping to prevent these risks. Insufficient or deviating cooling conditions in the water curtain of the secondary cooling zone are common causes for bleed-outs, especially during cast startCast start with the risk of water-melt explosions. They typically rely on the flow conditions in the sump, the stress-strain conditions in the solidifying shell and insufficient water supply for cooling. Hydro’s “water tester” is a robust tool to check the water flow rate and distribution in the water curtain of all types of casting molds. It is well accepted by operators due to its easy and ergonomic use. The thermopile-array based “bleed-outBleed-out detector” represents an even more detailed analysis tool of the cooling features of the used molds. It is a cost-efficient tool visualizing the water and temperature distribution in the secondary cooling zone suitable to trigger alarms or even automatic cast aborts. This paper describes the technological approach and application cases for both tools.

M. Badowski, D. Krings, G. U. Gruen, W. Droste, Ph. Meslage, B. Jaroni

Beryllium Reduction Potential in AlMg Cast Alloys

BerylliumBeryllium is used in many aluminium-magnesiumAluminium-magnesium alloys to minimize molten metal oxidationOxidation and oxide entrainment. As berylliumBeryllium containing dust and fumes have detrimental effects on health, its use has to be limited. The reduction potential of berylliumBeryllium has been investigated for AlMg3, AlMg5 and AlMg10 cast alloysCast alloys as well as Al99.85 as a reference material by thermogravimetric analysis (TGA). The samples were alloyed with Be contents between 3–57 ppm to measure the oxidationOxidation inhibiting effect over time. During TGA, the weight gain by oxidationOxidation of each sample was measured continuously for 21 h at 750 °C in laboratory scale. The results show that the Be inhibiting effect is lost after a period of time. The samples were analysed by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and electron microscopy (SEM) to further understand the oxidationOxidation mechanism. Finally, the results were used to derive a predictive modelPredictive model for the required Be content to protect an AlMg alloy.

J. Steglich, A. Basa, A. Kvithyld, N. Smith, I. Zerbin

Accurate Real-Time Elemental (LIBS) Analysis of Molten Aluminum and Aluminum Alloys

Real-time LIBSLIBS (laser induced breakdown spectroscopy) analysis for monitoring and process control in an aluminumAluminum smelter is reported. Chemical analysisChemical analysis was carried out directly in a casting launder as well as with robotic sample feedingFeeding at a crucibleCrucible skimming station. Using this system, ppm-level quantification limits have been demonstrated for certain trace elements. For most of the elements studied, measurement uncertainty is lower than observed in OES (optical emission spectroscopy) analysis on corresponding process samples. Furthermore, LIBSLIBS analysis allows the time-varying concentration of elements in the melt to be monitored on a minute-by-minute basis. Our results confirm that for many technologically important elements, LIBSLIBS analysis represents a competitive alternative to laboratory OES, provided that suitable access to the liquid aluminumAluminum can be ensured. This approach improves plant safety by reducing the need for manual sampling of liquid metal, eliminates operator-related errors in chemical analysisChemical analysis and is critical for automationAutomation of casthouseCasthouse operations.

Sveinn Hinrik Gudmundsson, Jon Matthiasson, Kristjan Leosson

Industrial Verification of Two Rotor Fluxing in Large Crucibles

CrucibleCrucible fluxingFluxing is a well known method to reduce the alkaline metal content in potroom metal in an Aluminium smelterAluminium smelter. By doing this the need to perform melt treatment inside the casthouseCasthouse furnaceFurnace will normally be eliminated. This approach has also made it possible with one-furnaceFurnace-practice inside the casthouseCasthouse, casting is done from the same furnaceFurnace as the potroom metal is poured into. Other benefits are also documented by crucibleCrucible fluxingFluxing as increased lifetime of the furnaceFurnace lining and reduced metal loss. Hycast has been supplying crucibleCrucible fluxingFluxing (RAM) to the AluminiumAluminium business for three decades. In this solution the active medium is AluminiumAluminium Fluoride (AlF3) which is added together with Argon to ensure mixing (RAM). Recently Hycast has developed a solution for crucibleCrucible fluxingFluxing in large crucibles with a closed lid used for crane tapping. This paper is about the different technical solutions and the measured performance during industrial operation. The main challenge when designing the new RAM was the closed lids on the crucibles. A small hatch in the lid gives access for the rotors into the crucibleCrucible. The AlF3 addition rate, rotor speed, and the effect of one versus two rotors are investigated. Halftimes of SodiumSodium (Na) for the two-rotor version is ~0.3 min/mt. For the one-rotor version the half time of SodiumSodium is ~0.5 min/mt. The temperature loss was lower than expected and the rotor torque higher than expected for the two-rotor RAM stations.

Terje Haugen, Arild Håkonsen, Vegard Innerdal

Dynafeed: An Improved Crucible Transfer System

Tilting tables are commonly used as a means for transferring liquid metal from crucibles to furnaces or other types of equipment, including open mold casting machines such as sow casters. Transferring metal from crucibles often requires a series of non-productive tasks including moving the crucibles manually with an overhead crane. The Dynafeed tilting table was developed to eliminate the requirement for an overhead crane, accepting the crucibleCrucible directly from the transport truck. A first version was developed for a sow casting machine, allowing for the use of larger crucibles while eliminating the overhead crane. Other configurations are used for transfer to furnaces and contingency sow casting. The purpose of this paper is to describe the principle of the Dynafeed and the various possibilities raised by this technology.

André Tremblay, Jean-Francois Desmeules, Martin Dubois

Metal Transfer from Furnace to Furnace—A Case Study

Siphoning is a well known method to transfer metal from a container to another while minimizing drossDross generation. It is often used to transfer the metal from crucibles to furnaces or from furnaceFurnace to furnaceFurnace. Many existing systems suffer from siphonSiphon blocking or slow cycle times. A system was recently designed and supplied to transfer metal from a melting furnaceFurnace to a casting furnaceFurnace. Fully automated operation allows for the transfer of a full load at the touch of a button. The unit is totally autonomous, featuring a preheating system and a positioning mechanism that detects the condition of the siphonSiphon during transfer. A full scale prototype was designed and built to test the control system with water prior to the commissioning. The purpose of this paper is to describe the application, its challenges and the solutions applied, to ensure above expectation performance.

Olivier Dion-Martin, Pierre Jeanroy, Jean-Francois Desmeules, Marek Varadinek

Heavily Loaded Areas in Aluminum Melting Furnaces and Possible Refractory Solutions

Due to the trend to modern melting and recyclingRecycling furnaceFurnace technologies, the requirements for the refractoriesRefractories in the AluminumAluminum CasthouseCasthouse are increasing constantly. The operating temperatures have increased and the chemical attack is more intense. Especially in the areas of the belly band, ramp slope and sill the established lining concepts have reached their limits. The previously well-proven anti-wetting agents of wear-lining material decomposes earlier and the concrete infiltrates with liquid AluminumAluminum. We have responded to these challenges by developing a novel monolithic wear lining refractory with an inorganic binder and a very effective anti-wetting agent. This special additive is highly temperature stable and thus still effective at increased process temperatures. By using the novel material, the life time of the refractory lining was increased significantly. This paper shares theoretical aspects of the refractory technology as well as practical experience and results of the collaborative work with Trimet AluminumAluminum SE.

Thomas Schemmel, Rüdiger Pfaar, Uwe Kremer

Mold Shape Control for Direct Chill Ingot Casting

AluminumAluminum direct chill ingot castingIngot casting with dynamic rolling face mold walls provides many benefits to casters and rolling mills. Among these are higher casting speeds, less scalp, mold size flexibility and more consistent ingot stacking. A newly developed system uses 3 active and 2 passive points on each rolling face mold wall to control the ingot’s profile. Positioning the points along the mold wall prior to a cast allows profile optimization for nearly any mold size. The active points are controlled to move the rolling face mold walls up to a predetermined position at any particular cast length. The mold rolling face displacement is developed to match the alloy, casting speed and other factors. The operational principle, as well as laboratory results are presented.

Craig Cordill

Continuous Monitoring of Butt Curl Development During DC Casting—Development and Application

Cast startCast start situations for rolling ingot DC castingDC casting can represent severe risks for cast shop workers due to unforeseen development of butt curlButt curl of individual ingots. Hydro’s R&D center Bonn has the ambition to provide procedures and related tools helping to preventing these risks. In order to react on the critical development of butt curlButt curl of individual ingots in a casting unit a monitoring of relative motion of the bottom side of the solidifying ingot to the starter block is required. This means a continuous distance measurement under extremely harsh conditions. Possible solutions must be watertight, heat resistant, need wireless data transmission capabilities and implementation and preparation of the system have to be user-friendly. Current status of the development includes real-time visualization and data storageStorage in the process control system. This paper describes the technological approach, the testing under plant conditions and application examples of the system.

Werner Ewald Droste, Daniel Krings, Gerd-Ulrich Gruen, Mark Badowski, Markus Hagen

Constellium’s Mould Technology for Al Alloy Slab DC Casting

DCC mould developments aim at meeting criteria either internal or external to the cast shop. To the first category belong operational robustness, mould simplicity, mould versatility in terms of alloys and water quality, that is the possibility to obtain very high recovery rates whatever the alloy hot crackingHot cracking or curling tendency, in any casthouseCasthouse regardless of its particular water supply. To the second category belongs the minimisation, potentially the suppression of butt sawing before rolling. Constellium has striven to suppress butt cracking during start-up and surface cracks in steady state. This has led us to reconsider the choice of jets angles and start-up strategies of the commercially available technologies, and eventually to develop our own mould technology, now patented and widely deployed within Constellium.

Ph. Jarry, O. Ribaud, L. Jouët-Pastré, E. Waz, P. Delaire, P.-Y. Menet, M. Bertherat, P. Celle

Fluid Flow Analyses and Meniscus Behavior During the Horizontal Single Belt Casting (HSBC) of Aluminum Alloy AA6111 Strips

The Horizontal Single Belt Casting (HSBC) process involves feedingFeeding molten metal, iso-kinetically, onto an intensively water-cooled, moving belt, which acts as the mold. Managing the bottom surface quality of the as-cast strip is a key factor in the success of the HSBC approach. The quality of strips is directly dependent on fluid flow behavior within the delivery system, the shape of the metal delivery system, the texture of the cooling substrate, meniscus behaviorMeniscus behavior at the oscillating triple point of contact between melt/cooling substrate/air at the refractory back-wall, as well as the interfacial heat transferHeat transfer between the melt and cooling substrate. The present research focusses on fluid flow analyses and meniscus behaviorMeniscus behavior during the HSBC casting of various aluminumAluminum alloys. High Performance Computational Fluid Dynamic Modelling was validated by full-scale casting experiments.

Roderick Guthrie, Mihaiela Isac, Donghui Li

Effect of Water Flow Distribution on the Performance of Aluminium Small-Form Ingot Chains

Small-form ingot castingIngot casting lines are widely used to produce pure and foundry aluminiumAluminium alloys due to their productivity and the convenience of small-form ingots for remelting and handling operations. The throughput of small-form ingot linesSmall-form ingot lines is typically determined by the length of the ingot chain. Longer chains allow higher productivity by maintaining the primary cooling time. To reduce this cooling time, fundamental understanding of the thermal dynamic is needed. This paper presents the effect of water flow distribution in cooling baths on ingot solidificationIngot solidification and ingot constraint stresses. The water flow parameters, in the cooling bath, were tested at three different sections. The complete ingot cooling profiles, mould temperature profiles and demoulding rate, as a function of the water flow distribution, were evaluated. Key process parametersProcess parameters and issues were identified during the study, and best practices were explored to secure ingot quality and casting performance.

Lei Pan, Eric Laplante, Francis Breton

Small Scale Oxidation Experiments on AlMg Alloys in Various Gas Fired Furnace Atmospheres

OxidationOxidation is of great interest in the casthouse, as oxidationOxidation equates to metal loss. Therefore, a method to study the oxidationOxidation in a casthouseCasthouse was developed and tested on AlMg alloys and AlMg alloys with berylliumBeryllium additions under a variety of atmospheres created by an airfuel or oxyfuel burners. Samples of around 65 grams with between 0 and 5% Mg were placed in small steel or ceramic crucibles and further placed in a gas-fired box furnaceFurnace for times between 10 min and 6 h. The sample mass was recorded after cooling to quantify the oxidationOxidation extent with respect to both alloy and atmosphereAtmosphere . Microscopic analysis of selected samples showed that a MgAl2O4 layer had formed on the surface and that at higher Mg contents internal oxidationOxidation occurred resulting in the formation of MgO or MgAl2O4 clusters in the melt. The results show promise for a method to give an increased understanding of the oxidationOxidation in the casthouseCasthouse .

A. Johansson, E. Solberg, M. Skramstad, T. Kvande, J. Lodin, N. Smith, M. Syvertsen, A. Kvithyld

Study of the Oxidation of an Al-5Mg Alloy in Various Industrial Melting Furnace Atmospheres

In an industrial furnaceFurnace , fired with a hydrocarbon-based fuel, the furnaceFurnace atmosphereAtmosphere will essentially consist of a mixture of the four species: CO2, H2O, O2 and N2, all of which thermodynamically will react with aluminiumAluminium . Earlier publications have addressed the question of the thermodynamic versus the kinetic driving forces for oxidationOxidation and drossDross formation of liquid aluminiumAluminium alloys. Most of these studies have been performed in a laboratory environment with samples in the order of magnitude of 1 g or less. This paper describes a series of tests, where 10 kg samples of an Al-5Mg alloy were molten in a pilot scale furnaceFurnace , using burners fired with LPG and LNG and with controlled flows of gas components to produce various mixtures of the four gaseous species. The weight gain of the samples were monitored to determine the degree of oxidationOxidation and drossDross formation.

Johannes Lodin, Martin Syvertsen, Anne Kvithyld, Anders Johansson, Egil Solberg, Thomas Kvande

Batscan™, Constellium In-melt Ultrasonic Inclusion Detector: Industrial Performance

The Constellium in-melt ultrasonic inclusion detector has been evaluated in the real conditions of an industrial castingCastings line. Various potential failure modes have been systematically investigated in order to develop reliable technical solutions in view of the final industrial version. The detector must meet strict requirements for industrial use. In particular, it must be fully automated and autonomous, with automatic safety procedures to preserve the device in case of metal level anomaly or other alert of the casting line supervision system. Data post-treatment has been developed on the acquisition system including a calibration procedure. In order to guarantee signal stability during the measurement, both the cooling system design and the assembly mode have been optimized. Typical events known to affect melt inclusion content will be illustrated, based on more than 1 year of industrial operation. This includes measurements at the casting furnace exit, degasser exit, and filter exit.

Jean-Louis Achard, Nicolas Ramel, Guido Beretta, Pierre-Yves Menet, Jocelyn Prigent, Pierre Le Brun

Benchmark and Practical Application of State of the Art Hydrogen Monitoring

The knowledge of the hydrogenHydrogen content in liquid aluminiumAluminium alloys is a prerequisite for an effective control of the degassingDegassing efficiency and therefore the quality of the final product. This paper describes the procedure and the results of an extensive benchmark study on the most common devices for online measurement of hydrogenHydrogen in castingCastings launders, AlscanAlscan and HycalHycal . Both devices were tested in lab scale experiments at various known hydrogenHydrogen levels, which were established by purging with different reference gas mixtures until equilibrium. In addition, extensive tests were carried out in a pilot castingCastings facility as well as in a production cast shop on different alloys and in various positions between holding furnace and castingCastings station. The results of these tests as well as the consequences for the following implementation and automation of the selected device are part of this paper.

A. Pelss, J. Morscheiser, S. Radwitz, J. Kremer, A. Gilles

Molten Aluminum Quality Evaluations for Thin Foil Products

In aluminumAluminum castingCastings, metal refining affects the quality of final material as well as the metal performance in the subsequent process. In particular, the importance of refining increases in foil product group as the thicknesses become thinner. PinholePinhole/hole performance is a consideration in the packaging foil product group. In this study, two different filters are used to refine 8XXX8XXX series aluminum alloyAluminum alloy during twin roll casting process. Inclusion analysis was performed from 8XXX8XXX series aluminum alloyAluminum alloy strips cast by industrial scale with optical emission spectrometer to observe effects of refining. The main examination of the study is the pinholePinhole/hole quantity and densityDensity analysis to determine the quality of final packaging foil?. All tests were evaluated by comparing the results of the 8XXX8XXX series aluminumAluminum sample cast with material produced using a standard filter.

Çisem Doğan, A. Ulaş Malcıoğlu, Anıl Ozkaya, Eren Toraman, Ali Ulus

Industrial Verification of One- and Two-Chamber Siphon Degassing

Removal of dissolved HydrogenHydrogen from liquid AluminiumAluminium prior to castingCastings is industrial standard today. This is done mainly to reduce porosityPorosity in the cast product but also to reduce hot tearing during casting and to improve mechanical propertiesMechanical properties of the finished product. The challenge the casthousesCasthouse face is to remove as much HydrogenHydrogen as possible with as low cost as possible. Cost drivers for degassingDegassing is energy and Argon consumption in addition to drain metal, maintenance and consumable parts. Hycast has for almost two decades supplied a drain free two-rotor siphon degassers for metal flow rates up to 75 mt/h (I-60 SIR), and has recently launched a one-rotor version for metal flow rates up to 25 mt/h (I-25 SIR). This paper is a summary of the industrial results gained over these years. The effect of the relative Argon flow rate to the metal flow rate, the alloy composition and the rotor speed on the removal efficiency is investigated. An analytical model is developed to estimate the effect of different process parameters and number of degassingDegassing chambers on the removal efficiency. One conclusion found from the measurements is that the HydrogenHydrogen concentration within one degassingDegassing chamber is close to constant - thus very close to complete mixing.

Arild Håkonsen, Terje Haugen

Evaluation of CFF and BPF in Pilot Scale Filtration Tests

Eight filtrationFiltration tests have been done at Hydro AluminiumAluminium’s reference centre at Sunndal. Two different grades of CFFCFF (Ceramic Foam FilterCeramic foam filter) and two different grits of BPFBPF (Bonded Particle Filter) from Pyrotek were tested. The alloy composition was the same for each test. The inclusion content in the melt was measured with LiMCALiMCA II and PoDFAPoDFA upstream and downstream the filter. Selected filters have been cut and analysed with image analysisImage analysis after use.

M. Syvertsen, I. Johansen, A. Kvithyld, S. Bao, U. Eriksen, B. E. Gihleengen, S. Akhtar, A. Bergin, A. Johansson

Dynaprime Filtration Technology Experience at Alcoa Baie-Comeau

The patented Dynaprime vibration assisted priming filter was developed in partnership by Alcoa and Dynamic Concept to provide high efficiency melt filtrationFiltration at competitive capital and operation costs. Following laboratory, pilot and plant testing, a first industrial unit was installed at the Baie-Comeau plant. After over a year of continuous operation, more than 100,000 t of critical products made including over 30,000 t of can body and can end, the technology is now mature and actual metallurgical and operational data is available. Several different alloys with different filtrationFiltration requirements are produced. The purpose of this paper is to present a summary of the plant experience with the equipment, including metallurgical results as well as operation and maintenance cost comparison with other filtrationFiltration technologies.

Francis Caron, Jean-Francois Desmeules

Improving Ultrasonic Melt Treatment Efficiency Through Flow Management: Acoustic Pressure Measurements and Numerical Simulations

The current challenge for upscaling the ultrasonic melt processingUltrasonic melt processing (USP) technology to industrial scale is in improving the treatment efficiency using a single-sonotrode setup. To achieve this, we suggest two innovative approaches: increasing the melt residence time and exploiting acoustic resonance. This can be achieved through flow management in a launder by partitions where the resonance length within the partitions is equal or at integer steps to the wavelength of the incident sound wave. This study focuses on acoustic pressureAcoustic pressure measurements at different partition configurations and flow conditions combined with numerical modelling of the process. The measurements are done both in liquid aluminumAluminum and in water as its transparent analogue. The acoustic pressureAcoustic pressure measurements are then used to assess melt treatment improvement through cavitationCavitation activity and pressure distribution in the launder as well as to verify and further develop the numerical model.

Tungky Subroto, Dmitry G. Eskin, Christopher Beckwith, Iakovos Tzanakis, Georgi Djambazov, Koulis Pericleous

Impact of TiB2 Particle Size Distribution on Grain Refining Effectiveness

Grain refiners of the Al–Ti–B system, including TiB2 particles, are added to molten aluminumAluminum to produce the fine grains. The effect of grain refinementGrain refinement significantly fluctuates among grain refinerGrain refiner manufacturers and the lots despite the same composition. Furthermore, although various features for the grain refiners exist, it is unclear which feature is the most effective for grain refiningGrain refining . The mechanism of grain refinementGrain refinement has been proposed that the TiB2 particles act as heterogeneous nuclei. The free growth model has become the standard model for the action of grain refiningGrain refining . This model assumes that the TiB2 particle size distribution influences the inoculation efficiency. However, there are few examples that verified the inoculation efficiency using a grain refinerGrain refiner with different TiB2 particle size distributions. In this study, the grain refinementGrain refinement effectiveness of several grain refiners using different manufacturers and different compositions was investigated. The TiB2 particle size distribution in the grain refinerGrain refiner was measured by image analysisImage analysis and applied to the grain size prediction model which was developed based on the free growth model. The experimental and calculated results were compared and discussed in order to clarify whether the new model can predict the grain size inoculated with each refiner.

Akihiro Minagawa

Effect of Nucleant Particle Size Distribution on the Grain Refining Efficiency of 7xxx Alloys

To refine the as-cast grains of aluminiumAluminium alloy products, the industry uses grain refiners of different natures, Al–Ti–B or Al–Ti–C. It is commonly known, that depending on their nature, grain refiners have different nucleant particle size distributions. In this work, we highlight the presence of significant differences in particle size distributions in grain refiners of the same nature depending on the producer, but also inconsistencies within production batches from the same manufacturer. We demonstrate the importance of the grain refinerGrain refiner nucleant size distribution on the grain refinerGrain refiner efficiency for aluminiumAluminium alloys by means of SEM analysis and grain refinerGrain refiner castingCastings tests. Based on our results, we emphasise the necessity of controlling the nucleant particle size distribution to assure grain refinerGrain refiner efficiency.

G. Salloum-Abou-Jaoude, Ph. Jarry, P. Celle, E. Sarrazin

Impact of Transition-Metal Elements on Grain Refiner Performance in AA6061

Grain refinementGrain refinement during aluminumAluminum castingCastings is beneficial for both Direct Chill (DC) casting of wrought alloys and shape casting of foundry alloys. The resulting equiaxed structure is essential for positive and predictable responses to post-casting treatments and final mechanical propertiesMechanical properties . In addition, the uniformity and refinement of the as-cast structure reduces hot-tearing susceptibility and thus leads to faster casting speeds. Recent developments on next-generation aluminumAluminum alloys incorporate transition metal elements to either enhance the amount of alpha iron-silicon intermetallicsIntermetallics , or modify fracture behavior through the precipitation of dispersoids during homogenization. The purpose of this investigation was to determine if certain of these transition-metal elements impact the grain refiningGrain refining performance of TiB2 in AA6061. Investigations were performed for Cr, V, and Zr as a function of time to determine if any substitutional reaction occurred during periods of time of interest to the casthouseCasthouse .

Elli Tindall, Samuel R. Wagstaff, Kathleen Bennett

Application Ultrasonic Technology Processing for Aluminum Treatment While Casting Slabs on Industrial Equipment of UC RUSAL

The article considers the opportunities of using ultrasonic treatmentUltrasonic treatment to create conditions conducive to modify of the structure, as well as conditions that reduce the consumption of the supplied modifying rod for large-sized slabs of 5052 alloy manufactured by DC castingDC casting . Established the effective power range of ultrasonic waves for influencing the melt and the effective flow rate of the modifying rod supplied together with the use of ultrasound. The reduction in modifier consumption is due to the effect of advanced cavitationCavitation on TiB2 agglomerates, as well as “activation”, i.e., wetting of potential nucleating particles, thereby creating more crystallization centers. It is shown that the use of ultrasonic treatmentUltrasonic treatment promotes the removal of dissolved gases from the melt in industrial production. The removal of gases, similar to the modifying of the structure, is promoted by cavitationCavitation , forming microzones of different partial pressure, grabbing the gases dissolved in the melt.

I. V. Kostin, A. Y. Krokhin, V. F. Frolov, S. G. Bochvar, I. V. Bobkov, N. E. Laschukhin

Influence of Liquid Jet Stirring and In-Situ Homogenization on the Intermetallics Formation During DC Casting of a 6xxx Al Alloy Rolling Ingot

Due to high cooling rate, the direct chill cast ingot solidifies under a non-equilibrium solidificationSolidification condition that results in the formation of non-equilibrium intermetallicsIntermetallics, which complicates the downstream processes. Therefore, it is essential to control the intermetallic formation during castingCastings. In the current study, we show the influence of jet stirringStirring and in situ homogenizationIn-situ homogenization on the formation of intermetallicsIntermetallics during DC castingDC casting of a 6xxx Al alloy rolling ingot. In particular, the intermetallic phase content through the ingot thickness has been characterized using various microscopes, a differential scanning colorimeter and X-ray diffractometer. Phenol intermetallic extraction has been used to facilitate the three dimensional chemistry and volume fraction of intermetallicsIntermetallics, with changes rationalized in terms of the effect of jet stirringStirring and in situ homogenizationIn situ homogenization pre-treatment.

S. Kumar, J. Cracroft, R. B. Wagstaff

Digital Manufacturing for Foundries 4.0

The concept of smart foundriesSmart foundries aims at integrating and enabling smart technologies for digitalization of manufacturing operations. Foundries 4.0 refer to the inclusion of Industry 4.0 Industry 4.0 principles in traditional foundries. The casting process is known to be one of the most energy-intensive processes. Enabling sensor-based technologies, such as the Internet of Things (IoTs) for condition monitoring, can be an efficient means to bring down the energy costs. IoTs can also be implemented for real-time waste-monitoring. Embedded sensors can be utilized in determining excessive loads during the casting operation. This is very useful to identify overloading and in avoiding potential damage to the castingsCastings . Introduction of Additive ManufacturingAdditive manufacturing can reduce cycle time and material consumption. This paper aims to introduce the concept of Foundries 4.0. The key focus is to highlight the integration of digital technologies in establishing foundries of the future. Challenges involved in the establishment of smart foundriesSmart foundries are also discussed. A case-study discussing establishment of energy-efficient smart foundriesSmart foundries is also presented in this work.

Prateek Saxena, Michail Papanikolaou, Emanuele Pagone, Konstantinos Salonitis, Mark R. Jolly

Integrating Fluid Simulation with Virtual Die Casting Machine for Industry 4.0 and Operator Training

High Pressure Die CastingDie Casting is a complex manufacturing process in which molten metal is forced into a mold cavity under high pressure where it then cools and solidifies. An interactive virtual trainingTraining simulator is being developed which integrates fluid flow simulations with die castingDie Casting machine parameters to improve operator understanding of the process and ultimately improve casting quality. Methods for combining fluid simulationSimulation results with tools from the game industry for virtual realityVirtual reality and augmented reality applications in industry 4.0 Industry 4.0 are discussed.

John Moreland, John Estrada, Edwin Mosquera, Kyle Toth, Armin K. Silaen, Chenn Q. Zhou

Numerical Simulation of Wire Rod Casting of AA1370 and AA6101 Alloys

Wire rod castingWire rod casting , where molten aluminumAluminum is continuously fed into a trapezoidal cross-section of a rotating copperCopper wheel, are facing challenging issues with respect to the quality of the wire rod. Valuable insight into the solidificationSolidification of the bar emerging from the castingCastings wheel can be provided by numerical simulations. These must account for complex thermal and mechanical processes, especially bar shrinkage inside the mould cavity leading to air gap formation and reduced heat transfer. Numerical simulationNumerical simulation of this process is challenging, and limited studies have been published. A three-dimensional thermo-mechanical model has been applied for casting of EC grade 1370 alloy. Comparison to existing measurements has been done to obtain confidence in the model results and the applied boundary conditions. The model has then been used for an Al–Mg–Si alloyHypereutectic Al/Si alloy (AA6101) to propose a new speed for the casting wheel.

Dag Lindholm, Shahid Akhtar, Dag Mortensen

Influence of Nozzle Shape on Near-Surface Segregation Formation During Twin-Roll Casting of Aluminum Strips

The near-surface segregationSegregation is a characteristic defect of twin-roll cast strips. Intergranular intrusions and bleeds rolled into the strip surface deteriorate the mechanical propertiesMechanical properties and corrosion resistance. The following mechanisms cause these segregations: periodic fluctuation of the melt meniscus and low-pressure zones between the rolls and the solidified aluminumAluminum shells. The aim of this study is to identify how strong the influence of the first mechanism is. To adjust the meniscus length, two different nozzles—one conventional with a butt end and one tailored with a pointed end—are utilized. The lab scale twin-roll cast trials for the production of 3 mm strips from the aluminum alloyAluminum alloy EN AW-1050 are conducted in the vertical plane. The microsections with a total length of up to 300 mm are analyzed to establish the intensity and regularity of distribution of surface bleeds along the strips. Additionally, their mechanical propertiesMechanical properties are compared.

Olexandr Grydin, Mykhailo Stolbchenko, Mirko Schaper

Effect of Ultrasonic Treatment on the Eutectic Phase and Cu Content in the Al Matrix of Large-Scale 2219 Al Alloy Ingot

The modificationModification of coarsening eutectic phaseEutectic phase is particularly important for the performance of large-scale ingotLarge-scale ingot. In this study, the area fraction of coarsening eutectic phaseEutectic phase and the Cu contentCu content in the Al matrix were compared between ingots with and without ultrasonic treatmentUltrasonic treatment. The morphology of the eutectic phaseEutectic phase was investigated by SEM. Optical emission spectroscopy was used to determine the macroscopic Cu contentCu content and EPMA was applied to detect the Cu contentCu content in the Al matrix. Results showed that Cu atoms distributed more uniformly along the radius of the ingot after ultrasonic treatmentUltrasonic treatment. Meanwhile, the higher area fraction of coarsening eutectic phaseEutectic phase usually leaded to lower Cu contentCu content in the Al matrix, which could decrease the solubility of Cu and deteriorate the mechanical performance of the large-scale ingots, while this phenomenon was ameliorated in the ingot with ultrasonic treatmentUltrasonic treatment.

Li Zhang, Xiaoqian Li, Ripeng Jiang, Ruiqing Li, Lihua Zhang

Influence of Alloying Additives on the Electrochemical Behavior of Cast Al-5Zn Alloys

Cast Al-5 wt% Zn alloys are well known for their cathodic protection applications as sacrificial anodesAnode. Based on the previous studies, the electrochemical behaviorElectrochemical behavior of these anodes can be enhanced by addition of alloying elementsAlloying elements. These elements can be modifiers as magnesium (Mg), barium (Ba), (Cd) and etc. or they can act as depassivators like in the case of Indium (In), tin (Sn), titanium (Ti) and thallium (Tl). In the current investigation, alloying additivesAdditives includes Mg and Sn were added during melting of Al-5 wt% Zn alloy and the samples were immersed in a sodium chloride solution for 15 days to investigate their behavior as sacrificial anodesAnode. The results were compared to the standard Al-5Zn-0.02In anodesAnode. It was observed that addition of Sn or Mg increases the corrosion rate if added in certain amounts, exceeding the amount of addition results in adverse effects in terms of the alloy application as sacrificial anodes.

Mohamed Eissa Moussa, Hoda Elkilany, Shimaa El-Hadad, Madiha Shoeib

Thermal Analysis and Microstructure of Al-12%Si-2.5%Cu-0.4%Mg Cast Alloy with Ce and/or La Rare Earth Metals

This article aims to investigate the modificationModification response of the grain refined Al-12%Si-2.5%Cu-0.4%Mg alloy to rare earth metals addition with various La and/or Ce levels. Thermal analysisThermal analysis was used to evaluate the influence of cooling rate and rare earth element addition. MicrostructureMicrostructure was examined using optical microscopy, image analysisImage analysis and scanning electron microscopy. The results showed that 0.8% Cerium and 0.7% La brought about full modificationModification of eutectic Si particles, while the addition of both 0.8 wt% La and 0.55 wt% Ce reduced the eutectic temperature by ~8.47 °C. The addition of Ce and/or La has a noticeable effect on decreasing the eutectic Si phase size (area and length) and aspect ratio and increasing the particle roundness and circularity. The Ce- and/or La- rich intermetallic compounds are detected such as Al5.52Si1.31(Cu0.41, Ce0.59)Fe0.24, Al5.51Si1.36(Cu0.4, Mg0.1, La0.5), Al6.9Si3.3(La0.69, Ce0.31) and Al7.7Si2.5Cu0.75 La0.98Ce0.5and are believed to play a role in reducing the modificationModification effect of both additions.

Mahmoud Tash, Waleed Khalifa, Iman El-Mahallawi

Numerical Simulation of Temperature Field in 6061 Aluminum Alloy Vertical Twin-Roll Casting Process

Due to the lightweight production technology of automobiles, the demand for aluminum alloys is increasing. Therefore, the casting speed is increased to improve the production efficiency, but the high-speed continuous casting makes it difficult to control the casting and rolling process. In this paper, a two-dimensional mathematical model of the 6061 aluminum alloy double-roller pool domain is established. The flow, heat transfer and solidification process in molten pool were simulated by FLUENT software using finite volume method. The simulation calculations were carried out for different process parameters (casting speed, cooling strength and casting temperature), and the influence of different process conditions on temperature field distribution and freezing point position was analyzed to determine the reasonable process parameters of the material under high-speed casting conditions. Numerical calculations are performed by the solidification/melting model of the FLUENT software to provide guidance for the 6061 aluminum alloy twin roll casting.

Chaopan Xie, Xiaoping Liang, Yu Wang

Cast Shop Technology: Recycling and Sustainability Joint Session

Frontmatter

Constellium R&D Approach in Recycling, From Lab to Industrial Scale

Tilting Rotating FurnaceTilting Rotating Furnace (TRF) is a widely used technology for aluminium scrapAluminium scrap recyclingRecycling. Although being based on a very simple concept, the optimal operating conditions are not easy to define due to the large number of process parameters and antagonist performance indicators (e.g. productivity, metal recoveryMetal recovery, emissions). In order to improve process understanding, a lab TRF has been developed to investigate the effect of key parameters and identify the mechanisms governing the process performance. R&D achievements done for the recyclingRecycling of Used Beverage CansUsed Beverage Cans (UBC) with this lab furnace are presented together with their implementation at industrial scale. As an example, we quantified the effect of burnerBurner settings, salt fluxSalt flux chemistry, scrap contamination on metal recoveryMetal recovery. Environmental concerns were also considered in the study. An approach to reduce the emission of Volatile Organic Compounds (VOC) during UBC recyclingRecycling was developed. Mechanisms are proposed and recommendations were implemented at industrial scale.

A. Pichat, A. Vassel, P. Y. Menet, L. Jouët-Pastre

Representative Sampling, Fractionation and Melting of Al-Scrap

The production of deoxidation granules for steel metallurgy is done by the re-melting of aluminium scrapAluminium scrap in a two-chamber furnace. In order to determine the amounts of aluminiumAluminium, non-metals and foreign metals in mixed scrap of an Austrian Al-smelter, representative sampling of Al-scrap is first carried out. Subsequently, the obtained sample is divided manually into the different fractions. These are, on the one hand, the fractions of aluminiumAluminium and foreign metals like Cu, Fe, Zn and brass, and on the other hand, non-metals such as plastics, glass, wood and fines. Accurate characterization of the separated fines is done by TGA, TC, XRF and XRD analysis. Furthermore, melting experiments of the scrap on laboratory scale into a primary aluminiumAluminium melt are conducted according to the industrial process. The results are of great importance, since the quality of the scrap influences the melting process significantly and the purchasing department must adjust accordingly.

Stefan Wibner, Helmut Antrekowitsch, Barbara Falkensammer

Recycling of Aluminium from Mixed Household Waste

AluminiumAluminium is used in packaging due to its densityDensity, strength and preservative capabilities. This paper outlines a methodology to evaluate the recyclability of aluminiumAluminium waste, where parameters of scrap type, pre-treatment and remelting conditions are alternated in a factorial design, with measurements of yield and analysis of metal quality. In preliminary experiments three aluminiumAluminium waste materials were evaluated for recyclability. The methodology was tested on one of the waste materials from mixed household waste, named Cans, and will be described in detail. Cans was decoated at 300 and 550 °C. The decoated material was then remelted, 4 separate additions of ~2 kg per experiment, by submerging the sample material in molten aluminiumMolten aluminium. PorosityPorosity, oxide inclusion content and alloy composition were analysed to determine metal quality. The experimental results show that the yield of remelting, drossDross formation relative to melted sample material and the alloy composition of the remelted metal is dependent on decoating temperature. In conclusion: Cans are recyclable, with good quality and yield, when decoated before melting. Decoating at 550 °C improves metal yield and oxide inclusion content compared to decoating at 300 °C, however it also reduces magnesium content in the resulting alloy. Hopefully the methodology is useful for assessing the recyclability of an aluminiumAluminium-rich waste and for evaluating the effects of various process parameters during recyclingRecycling on metal yield and quality.

Sigvart Eggen, Kurt Sandaunet, Leiv Kolbeinsen, Anne Kvithyld

An Assessment of Recyclability of Used Aluminium Coffee Capsules

As a result of increasing demands for aluminiumAluminium in numerous sectors such as construction, automotive and transportation, its rate of consumption has sharply risen in recent decades. AluminiumAluminium is also used in containers for food- and drinks packaging due to its good formability, low densityDensity and corrosion resistance. The use of aluminiumAluminium in everyday products lead to complex end-of-life waste, such as coffee capsulesCoffee capsules , requiring advanced recyclingRecycling processes to achieve high metal recoveryMetal recovery and quality, which is essential to reduce environmental impact and economic cost. This study focuses on the recyclability of used coffee capsulesCoffee capsules via remelting under a salt fluxSalt flux . Results were evaluated for different aspects such as metal yield, metal purity as well as gas generation during treatment.

Mertol Gökelma, Fabian Diaz, Ilayda Elif Öner, Bernd Friedrich, Gabriella Tranell

Fractional Solidification for Purification of Recycled Aluminium Alloys

RecyclingRecycling Al is an up-to-date topic nowadays due to the economic benefits and sustainabilitySustainability , in fact recyclingRecycling Al employs only 5% of the energy necessary for its extraction from bauxite ore, saving 9 ton of CO2CO2 per 1 tonne of Al recycled. In this researchResearch project the principles of fractional solidificationFractional solidification have been applied to reduce the amount of impurities in model recycled Al alloys. A set-up based on isothermal squeezingIsothermal squeezing of a semi-solid alloy has been developed and tested. The ultrasonic vibration applied to the semi-solid material has proven to enhance the purification achievable, up to 65% of reduction in the concentration. A number of potential impurities, such as Si, Ni, Cu, have been tested. The role of solute partitioning during the process has been evaluated and characterised by optical microscopy and modelling.

Susanna Venditti, Dmitry Eskin, Alain Jacot

A Rapid Method of Determining Salt Flux Melting Point and Composition

Salt fluxes are commonly used in the recyclingRecycling of dirty or high surface area aluminumAluminum scraps and drosses. The salt fluxes perform many functions such as stripping away the oxide films and promoting droplet coalescence, but to be effective they must be in a molten state. The most common class of salt fluxes used in aluminumAluminum recyclingRecycling contain a mixture of sodium chloride (NaCl) and potassium chloride (KCl), and often minor amounts of a fluoride compound such as cryoliteCryolite. Fluxes are specified to certain chemical compositions to produce a defined melting point of the fluxFlux. The NaCl–KCl phase diagram is a simple eutectic system. By measuring the liquidus temperature of the mixture it is possible to accurately back calculate the composition of the blend and verify that the delivered fluxFlux matches the desired specifications. This paper describes a practical method for measuring the liquidus temperature and then inferring the fluxFlux composition.

Ray D. Peterson

Recovery of Aluminium Metal Using Ultrasonic Technique and Production of Al–Si Hypereutectic Alloys from 6063 Alloy’s Black Dross Using Silicon Lumps and Flux

The present work aimed to use an alternative method for the pre-treatment of the black dross samples to remove the unwanted components like nonmetallic and salt content by using the immersion method with diluted nitric acid and sulfuric acid during ultrasonic treatment, the process consists of the following three (3) unit operations: a. Immersing the black dross samples in 500 ml beaker filled with tap water, 1.43 M HNO3 and 0.735 M H2SO4 overnight after that expose the beaker with dross to ultrasonic for 4 h. b. Filtering the aluminium lumps from the tap water containing soluble and partially soluble alkali oxides and nonmetallic through sieve (d = 2 mm—mesh no. 10). c. Drying the aluminium lumps in an electric furnace at 120 °C for 2 h.

G. M. Taha, Ahmed S. Aadli, A. A. Ebnalwaled

Automatic Skimming Procedure for Reducing Aluminium Losses and Maintaining the Uniform Quality of the Molten Metal

Among the parameters involved in the production of aluminiumAluminium alloys, particularly demanding in terms of regulation are those involved in drossDross skimming. To reduce the aluminium lossesAluminium losses and maintain the uniform qualityUniform quality of the skimming, the skimming depth (drossDross removal) should be limited, as much as possible, to near the interface between the drossDross layer and the molten metal. The purpose of this work was the development of an automatic skimmingAutomatic skimming procedure. The position of the skimming spoon was guided by a continuous measurement of the temperature gradient across the drossDross layer, with the thermocouples positioned on its bottom edge. The efficiency of this novel procedure was validated by continuous tracing of the specific amount of skimmed drossDross (SASD)—the mass of skimmed drossDross per mass of produced molten metal. Although the SASD depends on several parameters (alloy composition, applied fluxes, as well as melting/skimming parameters), it was recognized as a valuable quantitative indicator of the quality and the efficiency of the melting procedure as well as of the quality of the molten metal produced.

Varužan Kevorkijan, Uroš Kovačec, Sandi Žist

Evaluation of the Effect of CO2 Cover Gas on the Rate of Oxidation of an AlMgSi Alloy

Small additions of beryllium (Be) to aluminumAluminum magnesium (AlMg) alloys have proven to decrease their oxidationOxidation rate during industrial liquid metal handling. As Be can cause respiratory health issues, it is desirable to evaluate alternative methods to inhibit the oxidationOxidation rate. Earlier work has revealed that small amounts of carbonCarbon dioxide (CO2CO2) to the surrounding atmosphere has a positive effect. In the present study the oxidationOxidation behavior of an aluminumAluminum magnesium silicon (AlMgSi) alloy has been investigated using a Differential Scanning Calorimetric (DSC) unit equipped with a Thermogravimetric Analyzer (TGA). Changes in both the heat fluxFlux and the mass have been monitored during exposer to 20% argon (Ar)Ar and 80% synthetic airSynthetic air, 99.999% pure Ar, and a gaseous mixture of 20% Ar, 76% synthetic airSynthetic air and 4% CO2CO2 at 750 °C for 7 h. The results revealed a one-step mass gain when heated in synthetic airSynthetic air, giving a total mass gain of 12.33% and an oxide layer thickness of >15 µm. Pure Ar had a positive effect on the oxidationOxidation rate lowering the mass gain to 2.80% and a thickness of ~10 µm. A mass gain of only 0.46% and a continuous dense oxide layer of 200–400 nm, with an additional granular discontinuous oxide layer of ~2 µm underneath, was obtained during heating in 4% CO2CO2. This confirms that even in the case of the AlMgSi alloyAlMgSi alloy, small amounts of CO2CO2 have a significant inhibiting effect on the oxidationOxidation rate.

Cathrine Kyung Won Solem, Kai Erik Ekstrøm, Gabriella Tranell, Ragnhild E. Aune

Electrode Technology for Aluminum Production

Frontmatter

The Development of Anode Shape, Size and Assembly Designs—Past, Present and Future Needs

The current shortage of green energy supply to meet the growing demand for aluminiumAluminium , together with a requirement to lower their Carbon footprintCarbon footprint , is driving smelters to shift to a high productivity, minimum energy cell operation while targeting minimum anodeAnode consumption. The anodeAnode shape, size, and setting pattern in the cells all have an impact on both the energy efficiency and net carbonCarbon consumption. Slots have been introduced to lower the resistance of the electrolyte. This has enabled increases in cell line current, but there has been a consequential reduction in the anodeAnode to cathodeCathode distance and electrolyte volume. Slots have also reduced the driving force for electrolyte flow and mixing. Increasing anodeAnode mass in the cells has resulted in longer times for the anodeAnode to heat up and draw full current. Thus these changes have introduced greater spatial variation in cell conditions, which have impacted cell performance. This paper aims to open up discussion toward determining the ideal anodeAnode design for smelters beyond the year 2020.

Barry J. Welch

10 Years of Anode Research and Development: Alcoa and Université Laval Experience

In 2009, Alcoa started an extensive researchResearch and development program with several professors from Université Laval in Quebec City. The program, mainly oriented into advanced modeling, carbonCarbon materials and advanced statistics, was aimed at improving our R&D capability by enhancing our core technical expertise. Universities offer a diverse in-depth fundamental expertise that is not necessarily available in-house, where industrial researchers are oftentimes more oriented into applied researchResearch . Universities also provide hi-tech specialized laboratory equipment not available within typical industry laboratories. After 10 years collaboration between Alcoa and Université Laval, about 60 students have graduated with a M.Sc. or a Ph.D. degree. The following summarizes different results obtained throughout this fruitful journey as well as key learnings on developing and maintaining the relationship between UniversityUniversity and Industry partner.

Jayson Tessier, Julien Lauzon-Gauthier, Mario Fafard, Houshang Alamdari, Carl Duchesne, Louis Gosselin

Carbon Anode Raw Materials—Where Is the Cutting Edge?

The CPCCPC and CTPCTP raw materials used for anode productionAnode production are both manufactured from byproducts of other industries which makes the aluminumAluminum industry dependent on others for two key raw materials. Despite this, the industry has made steady improvements in anodeAnode quality and performance over the last 50 years. Production processes for CPCCPC and CTPCTP have become more sophisticated but changes in feedstock availability for these raw two materials are starting to be felt by the industry. Average CPCCPC quality has changed quite significantly over the last 10 years but the industry has adapted well and this is expected to continue in the future. By contrast, CTPCTP quality has been quite stable over the last 10 years but the impact of declining coal tar production is starting to be felt by the industry. The paper will review current and future challenges for anodeAnode producers and where the cutting edge for anodeAnode raw materials lies today.

Les Edwards

Solids Flow Considerations and Their Impact in Smelter Carbon Plant Operations and Product Quality

Segregation and lack of material flow are common problems in smelter carbon plants. These problems can significantly impact plant operations and product quality. An understanding of the (practical) science of material flow, especially in/out of silos, bins, and hoppers are described, along with critical flow properties. Specific examples of flow problems are covered, along with approach(es) to ensure proper design and retrofit processes to eliminate various flow and segregation problems. Emphasis is given to the modern approach of using of the Discrete Element Method (DEM) to model granular material flows.

Brian H. Pittenger, Andrés D. Orlando

How to Improve the Environmental Efficiency of the Hall-Heroult Process While Producing and Using Carbon Anodes

Carbon anodesCarbon anodes will likely stay as the primary reduction medium in aluminiumAluminium smelting for years to come, despite the ongoing development of inert anodesAnode . This is due to the excess production of petroleum cokePetroleum coke as a by-product of hydrocarbon distillation and the CO2CO2 profile of energy production, making inert anodeAnode technology likely best suited for regions with hydropower as opposed to e.g. coal power. This means that industry must increase the environmental performance of the conventional Hall-Heroult process. We list several levers by which this can be achieved from an anodeAnode producer’s perspective. These levers include: Direct, examining factors to increase the efficiency of anode productionAnode production Indirect, examining factors that increase Potline efficiency and fuel consumption, examining potential to use renewable materials in anode productionAnode production . We conclude that there is still has a lot of potential to reduce the carbon footprintCarbon footprint of the Hall-Heroult process. The presentation is a combination of a literature review, and several industry examples.

Antti Koulumies, Ana Maria Becerra, Paul Merlin, Lasse Piechowiak, Martin Zapke

Trends in Anode Carbon Production Projects

In response to market conditions, there has been a reduction in concurrent major AluminiumAluminium smelter projects in the western world. Such projects are now constructed on average approximately every 5 years, at best. This is compared to the boom the industry experienced in the 1990s and 2000s when concurrent or back-to-back projects were the norm. The reduced number of projects has led to a perceived slowdown in innovationInnovation. In this discussion, the focus is on the anode productionAnode production sector within aluminiumAluminium smelting operations. When projects are built back-to-back the market is busy and, in turn, the key industry project players are busy. They are fully staffed and looking for any means to win their next project and maintain market share. This can be accomplished by developing the next great idea that helps lower capital cost, reduce operating costs, or improve facility reliability. In a perfect world all of these would be achieved, i.e. it would be the next great idea that differentiates them from the competition. Back-to-back projects also bring the benefits of learning through feedback and continuous improvement. Technology providers, equipment suppliers and Consultants use the rapid progression of multiple projects to develop ideas, test those ideas, get plant feedback, and then make improvements for the next project. This momentum of development and continuous improvement cannot be maintained at the pace major smelting projects are executed today. The appetite for companies to maintain their market share has not dwindled. In fact, some might say it is at its most fierce; in the current period one missed opportunity may be the difference between continued operation or closing shop for good. However, without an abundance of projects to fuel innovationInnovation, a shift was bound to occur. Gone are the days of bullish aluminiumAluminium price trends. The major projects of today undergo a barrage of evaluations and must meet seemingly impossible financial hurdles. In the metals sector, aluminiumAluminium is one of the most scrutinized metals due to high capital costs and in general, a long time to market. Only projects with the lowest capital cost and shortest schedule to production ramp-up are now approved. This pressure to deliver projects faster and at a lower cost than ever before is felt by all participants in the industry. A natural response to this pressure is the trend seen today, where the key players have shifted their innovationInnovation efforts from technical expertise, to project executionExecution. As key players struggle to maintain market share and remain relevant to the few remaining projects, they are thinking outside the box, but with a focus on project delivery. Repeated project executionExecution and sustained R&D resources are no longer available to drive innovationInnovation in plant design. Adapting and right sizing an existing design gives an advantage with faster equipment procurement. This is one of two means to achieve the impossibly tight schedules demanded for the major projects of today. The other is modularizationModularization, which allows a facility to be partially (or completely) erected offsite, thus giving the potential to reduce labor costs and advance the construction sequence by delivering “pre-assembled” blocks of e.g. a paste plant to site. ReplicationReplication and modularizationModularization are two examples of the shift in focus towards project delivery. This trend, while not necessarily improving our knowledge of the fundamentals of aluminiumAluminium smelting processes, has been a tremendous source of achievement within the industry. In some cases, the “outside the box” approach to project delivery has made the difference between realizing a project to completion and simply shelving another study report to collect dust. However, while the “game changing” anode productionAnode production technical developments of the past may not be evident, the work that is being done within the sector should be recognised. For example, equipment to detect and analyze anodeAnode cracks, and measure overall anodeAnode quality are being developed and refined. The effort and work that has resulted in maintaining anodeAnode quality with a generally ever-decreasing petroleum cokePetroleum coke quality also has to be commended. Although they are not the step changes seen in the past, these incremental changes are nonetheless important. Finally, there is a need to address what will be the most important advance in the modern history of the aluminiumAluminium smelting industry if it is successfully implemented; a development that will make many current technologists obsolete. Tremendous effort and energy are being invested in the development and realization of a functioning and viable inert anodeAnode and wettable cathodeCathode multipolar cell, i.e. the “green” reduction technologies. Does this mean that carbon anodesCarbon anodes have, or will, reach a plateau? Will there be continued investment in carbonCarbon anodeAnode technologies, knowing that a massive step change may be near? This presentation and discussion will focus on these subjects and demonstrate that innovationInnovation within the carbonCarbon anodeAnode sector is happening, but perhaps, not in a form that is evident to all.

Derek Santangelo

Development of a Soft Sensor for Detecting Overpitched Green Anodes

Increase in coke variabilityParis, Adéline over the past few years has led to frequent changesDuchesne, Carl in thePoulin, Éric optimumLauzon-Gauthier, Julien pitch demand (OPD) defined as the amount of pitch that yields the best anode properties for a given dry aggregate mix. Exceeding the OPD may cause post-baking anode stickingAnode sticking problems, thereby requiring additional operator interventions when unloading the baking furnaces and increasing losses due to scrapped anodes. This paper describes a new soft sensorSoft sensor developed for early detection of anodes with the potential to have sticking problems based on electrical resistivity measurements. Five resistivities measured at different points on approximately 120,000 individual anodes were used to build a Principal Component Analysis (PCA)Principal Component Analysis (PCA) model. A correlation was found between the anode stickingAnode sticking potential and the electrical resistivity data. It was shown that a breakdown in this correlation, as measured by the statistics of the Squared Prediction Error (SPE), may be used to detect post-baking sticking problems.

Adéline Paris, Carl Duchesne, Éric Poulin, Julien Lauzon-Gauthier

Diffusion Measurements of CO2 Within Carbon Anodes for Aluminium Smelting

A study of the CO/CO2CO2 diffusion coefficientsDiffusion coefficients within the carbonCarbon anodeAnode and cryoliteCryolite was carried out. Gas diffusion experiments were conducted to measure the diffusion coefficient of CO2CO2 in conjunction with anode characterizationAnode characterization using Mercury Intrusion Porosimetry (MIP). The diffusion coefficient value obtained varied from 1.38 × 10−6 m2/s to 7.89 × 10−6 m2/s in the temperature range from 25 to 960 °C. In addition, the diffusion coefficient of CO2CO2 in cryoliteCryolite at 960 °C was predicted to be 2.74 × 10−9 m2/s. Two verification studies were attempted to measure the diffusion coefficient in cryoliteCryolite, but no reliable results were obtained. The results from this study suggest the gas transport for bubble growth is controlled by gas flow in the anodeAnode due to slower diffusion coefficient value in cryoliteCryolite which is three orders of magnitude lower when gas diffusion coefficient for CO2CO2 through the anodeAnode samples.

Epma Putri, Geoffrey Brooks, Graeme A. Snook, Lorentz Petter Lossius, Ingo Eick

Testing of SERMA Technology on Industrial Anodes for Quality Control for Aluminum Production

CarbonCarbon anodeAnode quality has a strong influence on the electrolytic process, cost, energy use, and environmental emissionsEnvironmental emissions. The current practice by visual inspection and the testing of cores taken from 1.5 to 2% of the anodesAnode produced is prone to errors. A more reliable quality controlQuality control is desirable. The SERMA technology gives the electrical resistivity distribution in industrial anodes (green or baked) based on a simple and non-intrusive measurement technique. Since the electrical resistivity is a good indicator of anodeAnode quality, SERMA can be used for on-line quality controlQuality control. Its use in the paste plant would help eliminate defective green anodes and avoid their further processing. Testing of baked anodesAnode would help save energy by eliminating the use of high-resistivity anodes during the electrolysis. The SERMA technology has been tested on a number of industrial anodes. This article presents the results for both green and baked anodes tested.

Yasar Kocaefe, Duygu Kocaefe, Dipankar Bhattacharyay, Abderrahmane Benzaoui, Jean-François Desmeules

Modelling of Gas Injection on Anode Baking Furnace and Application to Operations

In the aluminiumAluminium industry, the carbon anodesCarbon anodes are baked in the anode baking furnaceAnode baking furnace by means of the combustion of both the volatile matters emitted by the green anodesAnode and the fuel injected. The essential objectives for baking furnaces are to achieve a uniform baking level while optimizing the fuel consumption, maintaining the refractoryRefractory condition, and limiting the emissions. Those requirements are strongly influenced by the fuel injection in the heating sections, and the precise study of this phenomenon is essential to better grasp the impact of the process parameters. In this paper, a 3D model for the combustion of pulses of gas in the heating sections will be presented. This model focuses on the flame behaviour in order to precisely represent the gas pulses, the quality of the combustion, the heat transfer and the emissions. The effect of the parameter variations on operation will also be presented.

Sandra Besson, Solène Bache, Arnaud Bourgier, Jean-Philippe Schneider, Thierry Conte

Higher Baking and Production Levels in Anode Baking Furnaces and Associated Challenges

In the aluminiumAluminium industry anode bakingAnode baking is often one of the most critical steps to achieve the appropriate anodeAnode quality in a safe and cost effective manner. Furthermore, many plants aim to increase the baking level and/or their production. This requires the baking furnaces to be operated at higher temperatures and shorter anodeAnode cycles, all while keeping the process safe. To achieve this, the process has to be optimised to avoid the risks associated with unburnt volatiles and an uncontrolled pitch front as well as excessive temperature increases. The present paper describes projects that were simultaneously executed in two of Rio Tinto’s North American smelters and describes the work performed to achieve both a higher baking level and higher production. Optimisation of the baking curves is discussed, along with the issues that arose during the project and the solutions that were put in place.

SyedArif Ali, Charles Lebel-Tremblay, Pierre-Yves Brisson, Alexandre Gagnon

Major Reconstruction of Central Casing of Open Top Baking Furnace with a View to Increase Its Lifespan and Reduce the Total Costs Comparing to Full Reconstruction

AluminiumAluminium Company of Greece operates with success its anode baking furnaceAnode baking furnace since its start-up more than five decades ago. Thermal and mechanical stresses created by the baking process however affected the integrity of the concrete casingConcrete casing in the central part. Distortions, deformations and cracks were indeed visible in comparison to the outside part of the casing. This paper goes through the different phases undertaken by AluminiumAluminium Company of Greece in order to successfully develop and safely realize the replacement of the casing wallsCasing walls in the central passage as well as the anodeAnode conveyor supporting structure while limiting costs and impacts on production and anodeAnode inventory. The article details the technical challenges and innovative solutions as well as the project and operation organization put in place in order to realize the work without any safety incident and in a strict schedule of ninety days.

Christos Zarganis, Eftychia Liantza, Harilaos Dolgyras, Giannakis Christos, Kosmetatos Dionysios, Christophe Molinier, Arnaud Bourgier

Regulation and Management of Anode Baking Furnace Production Cycle During Green Anode Crisis

Manufacturing of anodeAnode in aluminiumAluminium smelter includes 3 stages like green anodeGreen anode production, baking of green anodeGreen anode and rodding of baked anodeAnode . Green anodes undergo baking process in order to remove pitch volatiles, enhance its thermal and electrical conductivity, and reduce its reactivity level. Anode baking processAnode baking process is carried out in an open top ring-type furnace. Both from the construction and operation point of view, anode baking processAnode baking process is the costliest stage of anodeAnode manufacturing process. In baking furnaces, green anodesAnode are loaded, baked and unloaded from the furnace on continuous basis. Thus, the unavailability of green anodeGreen anode will interrupt the baked anode productionAnode production as well as lead to stoppage of Baking furnace. This paper presents and discuss the management of a crisis situation created due to the unavailability of green anodes and how, by regulating the baking furnace fire cycleFire cycle duration, a possible situation of furnace stoppage was averted.

Kalpataru Samal, Suryakanta Nayak

Sustainable Spent Pot Line Management Guidance

Spent Pot LiningSpent pot lining (SPL) is generated as a solid waste from the primary aluminium electrolysisAluminium electrolysis process. Approximately 25 kg of SPL is produced per tonne of primary aluminiumAluminium and a significant amount of the SPL generated today is stored in secure facilities or sites, at or near, aluminiumAluminium smelters. SPL is classified as a hazardous wasteHazardous waste in many jurisdictions which can complicate its transportation and end-of-life processing. There are various commercial options for treating SPL and there is also ongoing researchResearch on the use of SPL as a feedstock into other industrial processes and there have been a number of commercial partnerships in recent times. The International AluminiumAluminium Institute (IAI) has developed industry guidanceIndustry guidance that describes good practices for sustainable SPL management taking into consideration that sustainable or good practice is dependent on site-specific issues, local constraints, risks and regulatory regimes. Case studies, data and other supporting information has been collated to provide a comprehensive overview to support sustainable management of SPL across the aluminiumAluminium industry.

Pernelle Nunez

Purification of Graphite by Thermal Vacuum Treatment of Spent Potlining

The aluminiumAluminium industry is striving towards a lower environmental footprint, and the management of spent potliningSpent potlining (SPL) is high on the agenda. The reuse and recyclingRecycling alternatives of SPL are limited primarily due to its content of sodium, fluorides and cyanide. In this work, a thermal vacuum process for the purification of first cut SPL has been tested. The process consists of a vacuum furnace and an off-gas condensation system. Small scale trials using 1000 g first cut SPL samples were carried out, with varying particle sizes and furnace temperatures. All tests demonstrated significant distillation of sodium fluoride and cryoliteCryolite. The remaining residues contained up to 91% graphiteGraphite, with minor amounts of contaminants such as aluminiumAluminium oxide and calcium fluoride. Conclusively, the vacuum treatment process shows great potential for reuse of the challenging material of first cut SPL.

Kristin Sundby, Ulf Sjöström, Ellen Myrvold, Morten Isaksen

The LCL&L Process: A Sustainable Solution for the Treatment and Recycling of Spent Pot Lining

Spent pot liningSpent pot lining (SPL) is a hazardous wasteHazardous waste generated from the internal lining of Al electrolytic pots consisting of carbonCarbon and refractoryRefractory bricks. This residue is classified as a dangerous waste mainly because of its contamination by fluorides and cyanides, and its reactivity with water, generating explosive gases. Over the last several years, the aluminumAluminum industry has made some progress on the SPL issue by recognizing that landfilling in unlined sites is no longer acceptable to most local communities. In 2008, Rio Tinto inaugurated a new plant in Jonquière, Québec for the treatment of spent pot liningSpent pot lining, based on the “Low-Caustic Leaching and Liming” process (LCL&L) developed at the Rio Tinto Arvida ResearchResearch and Development Centre in the early 1990s. This plant treats 80 kt of stored and fresh SPL annually. The hydrometallurgical treatment detoxifies SPL and produces inert by-products, which are then used as raw materials in industries such as the cement industry. This paper describes the LCL&L process characteristics, including valorization routes for its by-products and some recent process improvements to reduce treatment costs with improved energy efficiency.

Laurent Birry, Stephane Poirier

Experimental Study on the Collecting Agent for Spent Potlining Flotation Index Optimization

Froth flotation is a low-cost SPL recyclingRecycling technique, which separates carbonCarbon in spent potliningSpent potlining (SPL) from other components. The carbonCarbon is enriched in the flotation concentrate since it has outstanding hydrophobicity, and cryoliteCryolite is enriched in the flotation tailing. During the process, NaF in SPL dissolves in water and can be recovered by evaporation and crystallization, whilst cyanides are decomposed. The recyclingRecycling efficiency is evaluated by flotation index which is greatly affected by the collecting agentCollecting agent . In this study, the effects of types, dosing times, dosage and emulsification of collecting agentCollecting agent on the flotation index were studied. The optimized collecting agentCollecting agent was adopted in a quadruple-roughing double-cleaning closed-circuit experiment. The results indicated that carbonCarbon grade and recovery of concentrate were higher than 80% and 95%, respectively, while the NaAl11O17 and Na3AlF6 were successfully concentrated in the floatation tailing.

Nan Li, Lei Gao, Kinnor Chattopadhyay

Environmental Benefits of Using Spent Pot Lining (SPL) in Cement Production

Spent pot liningSpent pot lining (SPL) is a toxic waste material produced during the pot replacement process in the aluminiumAluminium industry. This paper presents a comprehensive environmental assessment of a case study in the United Arab Emirates (UAE), where SPL from Emirates Global AluminiumAluminium (EGA) was used as a feedstock at a cement plant in Ras Al Khaimah, UAE. Three areas of environmental concern were studied: fuel savings and CO2CO2 reductions, changes in NOx emissions, and raw material repurposing and toxic substance destruction. The use of SPL in cement productionCement production is shown to yield significant environmental benefits in terms of reducing emissions and coal consumption and destroying toxic substances. These changes are primarily attributed to the fluoride content in SPL creating fluoride fluxingFluoride fluxing effects that reduce the high temperature requirements of the cement kiln. This initiative bolsters the concept of a circular economyCircular economy in which different industries collaborate to improve environmental sustainabilitySustainability.

Mohammad Al Jawi, Chun Man Chow, Srinivasa Pujari, Michael Pan, Tanvi Kulkarni, Mohamed Mahmoud, Heba Akasha, Salman Abdulla

Characteristic Analysis of Hazardous Waste from Aluminum Reduction Industry

The carbonCarbon dust, aluminumAluminum drossDross and spent potliningSpent potlining from aluminum reductionAluminum reduction cells are considered to be hazardous materials because they contain a large amount of soluble fluoride salts and trace amounts of toxic cyanides. Piling them outside or in landfill sites create environmental pollution and ecological problems. In this paper, the hazardous wastes were comprehensively investigated with scanning electron microscopy (SEM) and X-ray diffraction (XRD). It is found that the chemical compositions of these wastes are very complicated. A variety of fluoride salts and aluminumAluminum metal were embedded in pores and openings of lining materials such as carbonCarbon, silicon carbide and refractories. As a result, a variety of compounds have been formed. The disposal of hazardous wasteHazardous waste is hampered by these complex components. This work provides some insight into dealing with such hazardous wasteHazardous waste.

Mingzhuang Xie, Han Lv, Tingting Lu, Hongliang Zhao, Rongbin Li, Fengqin Liu

Energy Saving in Hall–Héroult Cell by Optimization of Anode Assembly Design

Over the past few decades, intensive researchResearch was carried out on developing anodeAnode assembly designs to reduce energy consumption in aluminum reductionAluminum reduction cell. The present researchResearch work was carried out in the aluminumAluminum company of Egypt (Egyptalum) smelter. A new anodeAnode assembly design was developed by inserting multiple steel nailsSteel nails into stubhole. The total anode voltage dropAnode voltage drop of the current anodeAnode design and that of the proposed design have been studied using thermo-electrical analysis via ANSYS simulationSimulation software. The developed model was validated by comparing predictions with the measurements from in situ experiments. A significant improvement of the electrical contact resistanceElectrical contact resistance (ECR) between cast iron thimble and carbonCarbon was achieved by this new design. The mean voltageVoltage drop reduction reached 30 mV, which can achieve estimated annual cost saving of $1,228,800 USD/year for a smelter producing 320k tons of aluminumAluminum.

Abdul-Mageed M. Shamroukh, S. A. Salman, William Berends, W. A. Abdel-Fadeel, G. T. Abdel-Jaber

High Temperature Creep Behaviour of Carbon-Based Cathode Material for Aluminum Electrolysis

The creep strainCreep strain of the semi-graphitic commercial cathodeCathode material used for aluminum productionAluminum production was measured on solid cylinder sample. Experimental results were obtained using a modified Rapoport equipment for the cathodeCathode material during aluminum electrolysisAluminum electrolysis with a cryoliteCryolite mole ratio (NaF/AlF3) of 2.5 and at a temperature of 950 °C under different stress levels. The coincident method proposed previously was applied to model the creep strainCreep strain of carbonCarbon-based cathodeCathode material. The test data were processed, and the creep characteristics of the cathodeCathode material were determined based on Graham creep equation. A relationship between creep coefficients and stress has been developed. Then, the creep characteristics of the cathodeCathode material were obtained by finite element numerical simulations. The model results were in accordance with the experimental ones. This work will contribute to controlling the quality of the carbon cathodeCarbon cathode and improving the cell designCell design.

Wei Wang, Kai Sun

Redesigning of Current Carrying Conductor—The Energy Reduction Initiative in Low Amperage Hall-Héroult Cell

To decrease specific energySpecific energy consumption, we worked on Variable Stub and Solid Busbar project. In Variable Stub project, we changed the geometry of the stub, which decreased stub-to-carbonCarbon voltageVoltage drop. Our smelter has busbars of small cross-section. The busbar voltageVoltage drop is very high, which could be reduced by increasing the cross-sectional area. One pot has three sets of new welded busbars: one set on anodeAnode ring attached to the superstructure, two sets of half cathodeCathode ring welded to anodeAnode riser. This change-over requires shunting the next pot for 3–4 h which is taken back into the circuit after job completion. This paper will discuss the new modified potsModified pots, benefits, way forward, gain obtained after implementing the variable stub and solid busbar in the pots and also all the steps which are adopted to change the busbar without shunting the potline.

Ved Prakash Rai, Vibhav Upadhyay

Ready-to-Use Cathodes for the Hall-Héroult Process

Ready-to-Use CathodeReady-to-Use Cathode (RuC®) blocks based on the use of copperCopper inside the cathodeCathode have been implemented in many aluminumAluminum smelters since 2015. The concept and key performance parameters are presented, along with measurements of cathodeCathode resistance, collector barsCollector bars current distributions and temperature at cell start-up and as function of cell age. Today more than 500 RuC® cathodes are in operation and more RuC® cells are started every day. Significant energy savings and improvement of the cell magneto-hydrodynamicMagneto-hydrodynamic state are achieved. The reduction of the maximum cathodeCathode surface current densityDensity should lead to longer cathodeCathode life. The concept allows the avoidance of cast iron rodding and recovery of copperCopper at the relining time. A new generation of cathodeCathode is ready to be implemented.

Markus Pfeffer, Oscar Vera Garcia, Louis Bugnion, Laure von Kaenel

Mechanism Understanding of Sodium Penetration into Anthracite Cathodes: A Perspective from Diffusion Coefficients

Sodium penetrationSodium penetration into carbonCarbon cathodes is an important cause of cell failure and efficiency loss, but it is a formidable task to unravel the detailed mechanism experimentally. Combined with MD simulationSimulation and DFT calculation, several diffusion coefficientsDiffusion coefficients were acquired to quantitatively analyze the behaviors of sodium penetrationSodium penetration for the first time. Especially, the transport diffusion coefficient of sodium vapor in the large-scale realistic anthracite cathodeAnthracite cathodes model was calculated as 6.132 * 10−10 m2/s, which was in outstanding agreement with experimental results. Owing to lower diffusion energy barrier, sodium was found to migrate faster along the grain boundaries than the other two solid diffusion pathways. The striking difference of corresponding diffusion coefficientsDiffusion coefficients in the order of magnitude indicated that sodium may migrate predominantly by vapor migration, rather than through solid diffusion, at least in anthracite cathodesAnthracite cathodes with high porosityPorosity. This fundamental researchResearch would contribute to the understanding of sodium penetrationSodium penetration mechanism and the optimization of cathodeCathode industry in the future.

Jiaqi Li, Hongliang Zhang, Jingkun Wang, Yunrui Wang

Anhydrous Carbon Pellets—An Engineered CPC Raw Material

The paper reports on a new technology Rain CarbonCarbon has been developing to produce an engineered calcined petroleum cokePetroleum coke (CPCCPC) product. AgglomerationAgglomeration of green petroleum cokePetroleum coke (GPC) fines through either granulation/pelletizing or briquetting can be used to produce a CPCCPC product with improved properties. Pelletizing GPC fines can produce high bulk densityBulk density pellets hereafter referred to as anhydrous carbonCarbon pellets or ACPACP. ACPACP densifies when calcined to produce a high bulk densityBulk density, free flowing CPCCPC product. The spherical particle shapeParticle shape provides improved particle packing densities compared to irregular shaped CPCCPC particles during anode productionAnode production. The paper will summarize key results including pilot anodeAnode properties showing improvements in baked anodeAnode densityDensity, electrical resistivity and other properties when using calcined ACPACP. A key benefit is the ability to produce a fully engineered CPCCPC product and Rain CarbonCarbon is currently constructing full scale, commercial plants to produce ACPACP.

Les Edwards, Maia Hunt, Christopher Kuhnt

Influence of Particle Shape and Porosity on the Bulk Density of Anode Grade Petroleum Coke

Bulk densityBulk density is a key property of anodeAnode grade petroleum cokePetroleum coke used in aluminum smeltingAluminum smelting and many studies have been undertaken on this parameter. These include previous work by BP that showed how particle shapeParticle shape could be modified by using different crushing technologies, and that changing shape parameters (i.e. sphericity and convexity) significantly influences coke bulk densityBulk density . In this initial study, a single coke was used to keep coke porosityPorosity relatively constant. This study has now been extended to include the testing of a number of different petroleum cokes (calcined using diverse calcining technologies) and anodeAnode butt samples to vary porosityPorosity as well as shape. The results of the extended study confirmed the findings of the initial study and were used to populate a simple model of the factors that impact bulk densityBulk density . This was then used to estimate the relative influence of particle shapeParticle shape and porosityPorosity on coke bulk densityBulk density .

Frank Cannova, Mike Davidson, Barry Sadler

An EXAFS and XANES Study of V, Ni, and Fe Speciation in Cokes for Anodes Used in Aluminum Production

The work has recently been published in Metallurgical and Materials Transactions B ( https://doi.org/10.1007/s11663-019-01676-z ).

Gøril Jahrsengene, Hannah C. Wells, Camilla Sommerseth, Arne Petter Ratvik, Lorentz Petter Lossius, Katie H. Sizeland, Peter Kappen, Ann Mari Svensson, Richard G. Haverkamp

Additive Selection for Coal Tar Pitch Modification in Aluminium Industry

In the aluminiumAluminium industry, the quality of anodesAnode has a direct impact on the production cost, energy consumption, and environmental emissionsEnvironmental emissions. AnodeAnode properties are strongly affected by the quality of binding between coke and pitch. One of the most promising avenues to enhance this binding is the modificationModification of pitch properties using additivesAdditives. They help increase the concentration of pitch surface functional groups and consequently improve coke-pitch interactions. The current work was undertaken to establish an additiveAdditives selection method which would yield improved coke wettability by modified pitch. This article describes the method and presents the results for three different additivesAdditives. Non-modified and modified pitches were characterized by carrying out wettability tests and FTIRFTIR analyses. Coking values (CV) of non-modified and modified pitches were also measured. The results show that it is possible to improve coke-pitch interactions via the utilization of additivesAdditives .

Julie Bureau, Armita Rastegari, Duygu Kocaefe, Yasar Kocaefe, Hans Darmstadt

Charcoal and Use of Green Binder for Use in Carbon Anodes in the Aluminium Industry

Carbon anodesCarbon anodes for aluminiumAluminium production are produced from calcined petroleum cokePetroleum coke (CPCCPC), recycled anodeAnode butts and coal tar pitchCoal tar pitch (CTPCTP). The CO2CO2 produced during anodeAnode consumption contributes to a substantial amount of the CO2CO2 footprint of this industrial process. Charcoal from wood has been suggested to partly replace coke in anodesAnode but high porosityPorosity, low electrical resistivity and high ash content contributes negatively to final anodeAnode properties. In this work, charcoal from Siberian larchSiberian larch and spruceSpruce was produced by heat treatmentHeat treatment to 800, 1200 and 1400 ℃ and acid-washed with H2SO4. Acid-washingAcid-washing resulted in reduced metal impurity and the porosityPorosity decreased with increasing heat treatmentHeat treatment. Pilot anodes were made from CTPCTP, CPCCPC with some additions of spruceSpruce and larch charcoal. Another set of pilot anodes were produced using a green binder. Compared to reference anodes, the CO2CO2 reactivity of anodes containing larch was less affected compared to anodesAnode containing spruceSpruce. The green binder was found to be highly detrimental for the anodes’ CO2CO2 reactivity properties. Electrochemical consumption increased for anodes containing both green binder, larch and spruceSpruce compared to the reference anodeAnode.

Camilla Sommerseth, Ove Darell, Bjarte Øye, Anne Støre, Stein Rørvik

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