9th International Symposium on High-Temperature Metallurgical Processing

In conventional copper production, anode copper is produced from concentrate in three furnaces in a process that entails four oxidation steps and one reduction step. Three types of slags are produced that require further treatment to recover copper. Dongying Fangyuan Nonferrous Metals recently developed a simplified process which requires only two custom-designed furnaces instead of the conventional smelting, converting and refining furnaces. The first furnace continuously produces high-grade matte (>75 wt% Cu) that contains little iron (<2 wt% Fe). The liquid matte is continuously fed to the second furnace, which produces anode copper. The new process significantly reduces the capital and operating costs and increases productivity and environmental sustainability. This paper presents fundamental concepts that enable the simplified process to be developed. The detailed operations in Dongying Fangyuan Nonferrous Metals are also described.

Treatment of polymer-based wastes has a tremendous potential for generating alternative energy, reducing greenhouse gas emissions, creating economic and environmental benefits, and achieving a sustainable development of the energy sector. During the past few decades, plastic wastePlastic waste generation increased at a greater rate than the population, with the move towards single-use products. Also with raising the cost of oil-based products, greater emphasis should be placed upon the usage of plastic/polymer in the waste stream as a supplementary source of fuel. This study presents a techno-economicTechno-economic analysis of the recycling potential of plastic wastePlastic waste in AustraliaAustralia by evaluating the possible use of these wastes as a reductant in steel making incinerators. The study tries to shed light on a possible cost effective alternative route in the smart treatment of waste plastic in AustraliaAustralia.

Recently, effective utilization of by-product slag as aggregate for concrete has been expected from the viewpoints of depletion of natural crushed stone and suppression of environmental loads. We developed a new process for continuous solidification of blast furnace slag as coarse aggregate. In this process, molten slag is continuously poured into molds, and the slag is solidified at the thickness of 20–30 mm. The flow rate of the molten slag is 1 t/min, and maximum production per ladle is about 30 t. After solidification, blast furnace slag coarse aggregate (BFG) is produced by crushing and adjusting the particle size of the solidified slag. The new BFG has water absorption of less than 1%, and concrete containing the BFG has the same fresh property and compressive strength after 28 day as concrete using natural crushed stone aggregate.

This paper introduces an oxygen-enriched flash smelting (OFS) process for lead smelting. Compared with the bath smelting, OFS has many advantages, including wide adaptability, high yield, low energy consumption, little uncontrolled emission, and considerable metals recoveries. Test results showed that increasing CaO could effectively reduce lead content in the slag, and the appropriate mass ratios of FeO-to-SiO₂ and CaO-to-SiO₂ were 1.15 and 0.6, respectively. The testing and commissioning indicated when OFS was used to treat material containing 30% of lead, the residual lead in slag could decrease to 4–10%. Furthermore, after zinc volatilization using an ore-smelting electric furnace, contents of lead, zinc, silver, gold and copper in the final slag were below 2%, 2%, 6 g/L, 0.1 g/L and 1%, respectively. The total recoveries of lead, zinc, silver, gold, copper and sulfur were above 98, 90, 99.5, 99.5, 85 and 98%, respectively.

Iron ore sintering is an essential process in modern iron and steel production. It has the largest emission of the PM (particulate matter) in the iron and steel industry, accounting for about 40% of the total emission. The physical and chemical properties of PM₁₀ and PM_2.5 in the iron ore sintering were introduced, and the research development of PM emission reduction was also summarized. The potential future development of PM emission reduction by chemical agglomeration and capture in the iron ore sintering process was also carried out. The interface chemistry relationships between PM and polymer, such as sodium carboxy methyl cellulose (CMC) and polyacrylamide (PAM), in agglomerates were also investigated in this paper. It is significant to reveal the characteristics of PM and develop the emission reduction technology of PM for the cleaner production of iron ore sintering.

Spraying medium to achieve an energy-saving and emission reduction for iron ore sintering has been researched, such as spraying natural gas, coke oven gas, oxygen, sintering flue gas and gas from annular cooler. This paper focuses on effect of spraying steam on sintering surface on reduction of NOx and dioxin emissions in practical sintering production in Shougang Jingtang. It can be found that, with the increase of sintering bed spraying steam amount, NOx and dioxin of flue gas showed a decreasing trend. As spraying steam 1 t/h for 550 m2 sintering machine in Jingtang, NOx content decreases 2.6–9.5 mg/Nm3, and dioxin decreases 0.007–0.014 TEG ng/Nm3.

Based on the study of artificial neural networkArtificial neural network, the neural model was established for the prediction of germaniumGermanium extraction from zinc oxide dustZinc oxide dust by microwave alkaline roasting-waterWater leachingleachingMicrowave alkaline roasting. Alkali-material mass ratio, microwave heating temperature, liquid-solid ratio, aging time, leaching time and leaching temperature were the significant factors for the process. The results indicated that the neural network prediction model was reliable, and the forecast values fitted well with the actual experimental values. The model could be used to predict the regeneration experiments with high credibility and practical significance. The accuracy of convergence of the model reached 10−5.

The application of the bottom-blowing in the steelmaking process of EAF can effectively shorten the mixing time of the molten bath, accelerate the removal of carbon, phosphorus and sulfur, and improve the production efficiency and product quality. Information about the effects of changing molten steel velocity during the smelting process would help to accurately model molten bath dynamics. In this study, numerical simulation software was employed to simulate the EAF steelmaking process under variable eccentric bottom-blowing gas flow situations. Velocity field data were obtained for the different bottom-blowing schemes. When other nozzles’ bottom-blowing gas flow rates were maintained at 133 L/min, the average velocity of molten steel in EBT (Eccentric Bottom Tapping Area) was increased from 2.8 × 10−3 to 3.4 × 10−3 m/s with the eccentric gas flow rate of bottom-blowing from 100 to 267 L/min, the average velocity of molten steel in the bath increased from 4.3 × 10−3 to 4.6 × 10−3 m/s with the eccentric gas flow rate of bottom-blowing from 100 to 267 L/min.

This paper is a contribution to the theory and quantitative understanding of the processes for the production of magnesium, calcium and strontium metals by metallothermic process. In the present study, effect of reductant type was investigated. Thermodynamic simulation of system was made by Fact Sage 6.4 program. In order to produce magnesium metal, effects of reductants “FeSi, Al, Si and CaC₂” were investigated. To understand Calcium-oxideCalcium-oxide reduction system, effects of Al and CaF₂ addition were investigated for different temperatures. In the last simulations, SrO reduction parameters were simulated. Al used as main reductant and BaO, CaO, CaC₂ were added to green mixture as a functional additive. Finally probable phases and minimum reduction temperatures are determined.

The production and consumption of Direct Reduced Iron (DRI) are continuously increasing, as a consequence of the impact of shale gas extraction technology on the Natural Gas (NG) market. Considering this context, DRI may improve the Blast Furnace (BF), Electric arc Furnace (EAF) and LD converter’s productivities and consequently their competitiveness. In this work the results of a cooperative research conducted by PUC-Rio University and a Brazilian mining company are presented. Laboratory-scale simulation tests, using DR commercial pellets and typical industrial operational parameters of a benchmarked DR shaft furnace, were conducted and planned using statistical and factorial analysis. In the simulated experiments, the following three regions of the DR shaft furnace were considered: Reduction Zone (RZ), Transition Zone (TZ) and Cooling Zone (CZ). Three stages were considered in the research development: (i) the reactions and equations concerning pelletPellets Metallization metallization and Carbon precipitation were analyzed; (ii) experiments focused on the definition of the carburization kinetic equations occurring in the Transition and Cooling zones, and finally, (iii) aimed to develop the “METCARB” model, a computational program conceived to simulate mathematically the metallization and carbonization reactions along the height of the furnace. In conclusion, a comparison is made with industrial results in order to validate the resulting “METCARB” model.

The submerged lance smelting furnace (SLS) for copper smelting has been developed and used by Dongying Fangyuan Nonferrous Metals Co., Ltd. The technology has shown advantages such as high oxygen enrichment, good feed adaptability, short processing time, high SO₂ concentration for acid plant, and auto-thermal operation. In this study, computational fluid dynamics (CFD) was used to investigate the gas/matte two-phase flow characteristics and the chemical reactions in the SLS during typical operational conditions. The Eulerian-Eulerian approach was employed to model the phase interactions. The chemical reactions were modeled by calculating the mass transfer coefficients and using the eddy-dissipation model. The simulation was conducted using the commercial software ANSYS Fluent®. The developed CFD model is able to predict the flow, temperature, and species distributions inside the SLS under various operating conditions.

Calcium ferrite, as the main bonding phase in the sintering process, greatly influences the property of sintered ore. Ultrasonic vibration has been widely applied to the treatment of metals to improve the properties of metals. In this work, ultrasonic vibration was introduced into the calcium ferrite and numerical simulation was carried out by solving the Rayleigh-Plesset equation to investigate the influence of ultrasonic conditions, including frequency, power and initial radii of cavitation bubbles on the cavitation bubbling behavior in calcium ferrite melt. The results indicated that lower ultrasonic frequency, higher power, and an appropriate initial radius of bubble promotes ultrasonic cavitation.

Commercial ceramic carbide operations require large thermal and mechanical energy inputs in order to produce a powder product. A process that could reduce the energy requirements needed to make these materials would allow for these materials to be implemented in a greater number of industrial applications. In this study, silicon carbide (SiC), tungsten carbide (WC), and molybdenum carbide (Mo₂C) were synthesized via the carbothermal reduction of activated carbon loaded with silicate, tungstate, and molybdate anions adsorbed from aqueous solutions. Carburization was carried out under reducing and inert gas atmospheres, at temperatures lower than those utilized by commercial operations. Silicon carbide “whiskers” were synthesized under H₂ at 1400 °C, while molybdenum carbide and mixed crystals of WC, W₂C, and W were synthesized at temperatures below 1000 °C. X-ray diffraction and scanning electron microscopy were used to characterize the carburization products, and inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to determine the degree of adsorption onto the activated carbon matrix.

In the 1990s, LiFePO₄ (LFP) was discovered as a cathode material for lithium ion batteries and was successfully used in the variety of devices such as power tools, E-bikes and grid accumulators. New challenges associated with use of lithium ion batteries for automotive applications demand higher performance and operating requirements, yet these requirements need to be achieved at affordable cost and without compromising vehicle safety. The advantages of LFP as a cathode material include thermal stability, limited environmental impact and potential of low cost as compared to the cathode chemistries containing cobalt. Currently, solid state and hydrothermal processes are used to synthesize LFP at the industrial scale. However, they require multiple, time-consuming steps and costly precursors. Recently, a melting-casting process to produce LFP cathode material was investigated. The motivation behind this new process is the great flexibility of raw materials including chemical makeup and particle size, and the use of lower cost, commodity chemicals, with the benefits of increased kinetics in the molten state and energy efficiencies leading to overall process cost savings. Also, if successful this process could represent a novel application of conventional casting. Melting lithium-, iron- and phosphorus-bearing precursors in near stoichiometric ratios and casting LFP material that forms around 1000 °C requires fewer processing steps and shorter reaction time. Initially, electric resistance furnaces were utilized to melt the precursors to synthesize LFP. In this investigation, induction furnace was utilized to significantly reduce the melting cycle time. Various precursors and process parameters were tested from small laboratory samples of less than 1 kg to pilot-scale casting of approximately 40 kg. Cast LFP samples were evaluated using SEM/EDX microscope, differential scanning calorimetry, thermal analysis, X-ray diffraction and battery assemblies in coin cells, and compared against commercial LFP product.

The first bottom blown copper smelting furnace (BBF) has been successfully operated for 10 years at Dongying Fangyuan Nonferrous Metals. In addition to many advantages of the BBF reported previously, stable operation with spinel-containing slags enabled the BBF refractories to achieve three-year campaign life. Understanding of the degradation mechanisms of the magnesia-chromite refractory will be able to further prolong the service life of the refractories and develop new refractories. In the present study, the post-mortem refractories were collected from different locations of the BBF during the annual maintenance. It is the first systematic study for the used refractories of a BBF. The phases present in the refractories and their compositions have been determined by Electron Probe X-Ray Microanalysis. The degradation mechanisms of the refractories are discussed based on the analyses. The results will be used to optimize the operation and select proper refractories in the furnaces.

Perovskite easily forms during sintering of vanadium titanium magnetite (VTM) and is unfavorable for the following blast furnace. Steelmaking can concomitantly produce a great quantity of oxidized scale composed mainly of FeO and Fe₃O₄. Calcium ferrite (CaO·Fe₂O₃, CF) can be formed by oxidized scale with lime in air atmosphere and then added to the VTM during sintering. X-ray diffraction (XRD) results indicated that perovskite is not generated at low temperature but only when the temperature increases to 1473 K in the CF–TiO₂ system. Therefore, VTM sintering can be performed with a low-temperature process with doping of CF. Perovskite formation is mainly divided into two steps. First, CF melts and produces CaO. TiO₂ and CaO then combine to produce perovskite. This paper also discussed the reaction mechanism of CaO–Fe₂O₃–TiO₂ ternary system to compare the generation routes of perovskite.

In recent years, a new process of “direct reduction-electric furnace smelting separation” has been put forward and developed for recovering the iron, vanadium, titanium and chromium to make full use of the chromium-bearing vanadium titanium magnetite. In the present work, FactSage, one of the most frequently-used thermodynamic calculation software, was used to calculate the migration of Fe, V, Cr and Ti with different n_C/n_O (mole ratio of carbon and oxygen). The calculation results indicate that the recoveries of Fe, V and Cr increase with increasing n_C/n_O and temperature respectively. In addition, the recoveries of Fe, V and Cr are up to 90% when the n_C/n_O value is more than 1.15.

Lime was made by the calcination of limestone in a high pressure resistance furnace. The lime mineralogical phases and micro-morphologies was characterized by field emission scanning electron microscopy (FE-SEM). The lime activity degree was determined by acid-base titration, and the lime pore distribution was measured by mercury intrusion porosimetry (MIP). The results show that with the increase of calcination pressure, the lime activity degree is increased, and the lime develops a large pore structure. The desulphurization experiments were carried out in the induction melting furnace using active lime with different activity degrees as a desulfurizer. The results show that the desulfurization performance of lime is closely related to the activity degree. There is a strong positive linear relationship between the desulfurization rate and the lime’s activity degree.

Continuous development of lead recycling technologies has driven the increasing contribution of secondary lead in battery manufacturing over the years. This review presents and compares the different technologies available for pyrometallurgical processing of secondary lead materials. Smelting is most often achieved in reverberatory, blast, rotary or electric arc furnaces, using single or two stage routes. Thermal refining is the most common technique used for the production of lead and its alloys. Some improvements in battery breaking technologies and emission control have also specifically contributed to improve the performance of the smelting and refining units. Recycling lead is facing the challenge of increasing production while meeting more and more stringent regulations. This review will also include an analysis of the current secondary lead market as well as an economic outlook for the years to come in regards to rapidly changing environmental standards.

In this study, some experiments were performed for the dimensional control, pre-treatment, getting salt, metallic aluminum and aluminum oxide into the solution of 15 kg aluminum black dross obtained from a private company which recycles aluminium drosses. Water leaching experiments are done for removing salts and aluminum nitride. Temperature stirring speed, solid-liquid rate are investigated while water leaching experiments. Removing of AlN is provided at 25 °C at a rate of 42.48%, at 80 °C at a rate of 86.4%. Leaching experiments performed with NaOH. NaOH concentration and time was analyzed. Efficiency of including metallic aluminum into the solution is determined to be 98% approximately. Melting (fusion) experiments were performed with NaOH at high temperatures to include aluminum oxide in the structure of the remaining after dissolving process into the solution and after dissolving the resulting structures in water, efficiency of including aluminum into the solution is determined to be 85%.

Zinc is widely used for galvanization of steel plates due to its high corrosion resistance. Steel scraps containing waste zinc-coated steel plates are remelted for recycling of steel in electric arc furnace (EAF) process, in which zinc is concentrated in EAF dust ranging from 10 to 40 mass%. Therefore, recycling of zinc from EAF dust is important to secure zinc resource. Our group has proposed selective chlorination and evaporation method recovering zinc as a form of chloride from EAF dust. Since recovered zinc chloride may contain lead, iron and copper as impurities, purification of zinc chloride is essential for production of highly pure metallic zinc. In the present study, removal of lead chloride from molten zinc chloride-alkaliMolten zinc chloride-alkali chloride by cementation reaction adding zinc was investigated. Experimental results were analyzed and discussed thermodynamically and kinetically as well as the feasibility and limitation of this process were examined.

Pyrometallurgical processes for recovering platinum group metals (PGMsPGMs) from spent catalystSpent catalyst have been the focus of current research for many years. They suffer from high energy consumption, large trapping agent consumption and huge slag production. Because of versatility of PGMs-containing spent catalystsSpent catalyst, comprehensive recovery of valuable metals from these catalysts from an experimental point of view remains a challenge. In this study, thermodynamic analysisThermodynamic analysis of pyrometallurgical smeltingSmelting process in the presence of various additives for efficient recovery of PGMsPGMs was performed. It showed that addition of sodium saltsSodium salts would promote the migration and separation of the precious metals from carrier of the spent catalystSpent catalyst. By replacing calcium oxide with sodium carbonate and sodium borate, the smeltingSmelting temperature could be reduced by more than 200 °C, which agreed well with the experimental findings.

FFC process could be used to prepare titanium foams. The mixed oxides CaO-TiO₂ with mole ratio 1:2 were sintered into CaTiO₃-TiO₂ mixture. CaTiO₃-TiO₂ was then used as cathode and electrolyzed in molten CaCl₂ to prepare porous titanium. The porous titanium with the porosity of about 72.15% was first fabricated. The internal pores are in the presence of circular cavities and the pore size is in the range of 50–100 μm. Compared with the powder metallurgy technique using the space-holder this method promises to be lower cost and less processing. It is potential to fabricate titanium foams using FFC process.

The copper in slag is mainly in the form of Cu₂S, and it’s easy to make matte suspended in slag. The sulfur in slag can be removed by oxidative process, and the copper sulfides can be converted into oxides, then the copper can be easily reduced and separated. Thermodynamic calculation by FactSage7.0 shows that the sulfur in slag can be removed by air, while the activity of Cu₂O will increase, and the Cu₂S cannot be reduced, while Cu₂O is easily reduced into metal. The oxidation and reduction of molten copper slag were carried out and agreed well with theoretical calculations. Sulfur in slag can be dropped to 0.23 wt%, and the utilization rate of air is in the range of 14.98–73.39%. The copper recovery rate can reach 83.82% and the residue copper can be reduced to 0.28 wt%.

SiO₂ and Al₂O₃ in the metallurgical slagMetallurgical slag of nickel laterite ore have great recyclingRecycling values. In this work, Si and Al were extracted from the slag in NaOH based molten saltsMolten salts through alkali roasting and water leaching process for preparing zeolite materials. The extraction ratio of SiO₂ increases with increased temperature and appropriately prolonged time, and more than 80% SiO₂ can be recycled from the slag after roasting at 550 °C. Si and Al from the slag are in the filtered liquor for producing zeolite materials, while Mg, Ca, Fe and other impurities remain in the leached residues. Adding Na₂CO₃ into the alkalin-slag roasting process can reduce the amount of pure NaOH used with minor decrease in extraction ratio of SiO₂, while make better separation of Ca to avoid it getting into the filtered liquor. Adding Al₂O₃ into the alkalin roasting process can replace part of more expensive NaAlO₂ addition that is required for preparing zeotite material, which may bring out a minor decrease in extraction ratio of SiO₂ due to formation of NaAlSiO₄ in the filtered residues. Quality X zeolite and 4A zeolite materials can be made from the starting liquor containing Si and Al recycled from the laterite nickel slag through alkali roasting and water leaching process.

Typical copper drossCopper dross, the byproduct of lead bullion pyrometallurgical refining for copper removal, mainly contains Pb, Cu, S, As, Sb and Sn etc. In traditional treatment process, copper drossCopper dross is transformed to be copper matte by smelting with iron scarp and iron pyrite. Here, a new treatment process of converting-vacuum distillation (CVD) was proposed and investigated. Based on this concept, the converting process was tentatively investigated in this paper. The results of element distribution of converting samples showed the sample has three layers. The upper layer is mainly sulfides of lead and copper, the middle layer is mainly copper arsenide, and the lower layer is lead arsenide and crude lead. On the condition of oxygen flow rate 400 ml/min, the converting temperature 1000 °C, the holding time 1 h, the converting time 10 min, the lead copper alloy containing 0.17% S was obtained.

Carbon steels have less than 0.02% copper and have low atmospheric corrosion resistance. The addition of at least 0.20 wt% Cu improves this property. Also, 0.8 wt% Cu in steel shows a hardening potential for developing high strength corrosion resistant steels. Copper slags containing 42–45% of iron, silica and minor amounts of copper were used for producing Fe–Cu alloys by reducing the oxides contained in the slag to obtain a Fe-0.84 wt% Cu alloy, which could be suitable as feeding material to manufacture a corrosion resistance steel, and also would be an alternative for minimizing the copper industry’s environmental impact, and to introduce the application of the Circular Economy concept to the natural resources exploitation, especially in countries where their economy is strongly based in mining and metallurgical extraction.

As a result of the consumption and the rising cost of raw materials for ironmaking, steel producers have increased their utilization of low-cost, low-grade raw materials such as high alumina iron ore. The effect of Al₂O₃ and the Al₂O₃/SiO₂ ratio on the viscosity, surface tension and sulfide capacity of the CaO–SiO₂–Al₂O₃–MgO–TiO₂ blast furnace slag system were studied in the present work. At a fixed CaO/SiO₂ ratio of 1.20, 9 mass pct MgO, and 1 mass pct TiO₂, the viscosity increases with an increase in Al₂O₃ content at a range of 16–24 mass pct, and decreases when the Al₂O₃ is higher than 24 mass pct. Increasing Al₂O₃/SiO₂ from 0.47 to 0.92 causes a slight decrease in viscosity of the slags and has an opposite effect when Al₂O₃/SiO₂ is more than 0.92. The surface tension increases with increasing Al₂O₃ content at a fixed Al₂O₃ content and Al₂O₃/SiO₂ at a fixed CaO content. The desulfurizing capacity decreases with increasing of Al₂O₃ content, while increases with increasing Al₂O₃/SiO₂ at a fixed CaO content.

Electro-titania slag is generally used as the raw material for titanium dioxide production by sulfate process. The phase composition of titanium as well as their disseminated grain size have significant effect on the acidolysis of titanium. Anosovite is considered as the most favorable Ti-bearing phase due to its high acidolysis efficiency, while silicates and rutile are not soluble in concentrated sulfuric acid. Different cooling rates will play a significant effect on the phase structure and particle size, which directly affects the acidolysis ratio of titania slag. In this paper, the influence on acidolysis ratio of titania slag at different cooling rates was studied. The results revealed that slower cooling rate resulted in the formation of larger particle size and a comparatively higher acidolysis ratio was obtained. On the contrast, rapid cooling was disadvantageous to the leaching of titanium as the smaller particle size anosovite was wrapped by glass phases.

Ferrous-calcium-silicate (FCS) based slag has been used in the copper industry over the last two decades. The FCS slag has also been used in a secondary copper processing such as in black copper smelting which has different operation conditions compared to that of typical primary copper processing. In the process, a variety of copper bearing scraps from sources such as industrial waste, consumer waste and electronic waste (e-waste) are used. The valuable metals in these secondary resources are distributed in different phases during the process. Understanding the behaviour of the valuable elements at the relevant conditions is vital for optimizing the process and to maximize the recovery of the elements. In this study, we investigated the structure of Ge-containing FCS-based slag at different conditions (oxygen partial pressure and temperature) using Fourier-Transform Infrared (FTIR) spectroscopy to explore the effect of the polymerization on the behaviour of the valuable element Ge in the slag. It was found that experimental parameters significantly influence the slag structure, and therefore, the partitioning of Ge in the slag. A correlation between the distribution ratio of Ge and the slag structure has developed in the current study.

Steelmaking slag contains useful elements such as P and Mn. Generally, in the carbothermic reduction of slag, not only P but also Mn are reduced and a Fe–P–Mn alloy is formed. In this study, the possibility of the separation of Mn and P was investigated. A mixture of synthesized slag and graphite was heated at 1773 K, and the compositions of the separated slag and metal were analyzed. The results showed that with a decrease in basicity, the reduction of P was enhanced but that of Mn was suppressed. Thus, under an optimum condition, steelmaking slag was separated into a Fe–P alloy and a high MnO-containing slag. Although further investigation is necessary, the formed alloy and slag could be used as raw materials for fertilizers and Fe–Mn alloys, respectively. This paper elucidates the concept of this process and the results of the fundamental experiments.

An oxygen sensor of zirconia-based solid electrolytes for in situ measurements of oxygen potential in high titanium slag was developed in the present study. With the facility, series of measurements of electromotive force were successfully conducted for different titanium slags at 1998 K under an argon atmosphere. Oxygen potential in the slag was calculated by the measured EMF and simultaneous readings of temperature using the modified Nernst equation. In addition, the relationship between slag compositions and the oxygen potential in the slag was explored in detail. It has been found that the oxygen potential increases with increasing FeO content in the slag and decreases with the increasing Ti₂O₃ content in the slag. The oxygen potential in the slag has been calculated thermodynamically and compared with the experimental measurements. The results showed that oxygen potential in the slag may be controlled by FeO/Fe equilibrium reaction.

An experimental investigation of the precipitation behavior of the Dy₂O₃ containing slag during cooling was carried out in this work. The slag with composition 45 wt% SiO₂—49 wt% CaO—6 wt% Dy₂O₃ was equilibrated at 1673, 1773 and 1873 K for 24 h in an argon atmosphere, and then quenched in water to determine the phase relations. The composition and microstructure of the equilibrated phases of the systems were determined by EPMA/WDS. The precipitation behavior of the REEs containing phases during cooling was studied by using an in-situ confocal scanning laser microscope (CLSM) observation technique combined with an infrared imaging furnace heating (IIF). Data resulting from this work aims to support further investigation on separation of rare earths from metallurgical slags.

The most used technology for recycling of spent alkaline batteries consists of crushing, magnetic separation and processing of the nonmagnetic fraction, black mass, using a rotary kiln. In the process only zinc is recovered and all manganese in the black mass is lost. According to the EU regulation for recycling of batteries, more than 50% of batteries should be recovered. To meet the demand, Swerea MEFOS has together with a major battery recycler IsoLogistics in Finland and Sweden developed technologies for efficient recovery of zinc and manganese aiming for >50% recovery. This paper will focus on a treatment process using a DC furnace to produce a ZnO- and a MnO-product. The process has been demonstrated in pilot scale, 1 ton/h. The major outcomes will be highlighted. Another approach by using thermal vacuum technology for distillation of zinc metal has also been demonstrated in laboratory scale which is also reported in this paper.

Exothermic riser sleeves are important tools to increase solidification duration, particularly for iron-steel casting. Increasing the time to solidus improved casting product quality by minimizing cavities. Therefore, process costs were significantly reduced. In comparison with the use of unsleeved risers, exothermic riser sleeves retain up to 30–35% of the heat and increase the duration to solidus by nearly 50%. Exothermic riser sleeves are a mixture of metallothermic-based exothermic and insulating materials that are manufactured in different sizes and shapes. Various suppliers produce these sleeves in different compositions. However, the designers must clearly understand the thermochemical and thermophysical properties. The purpose of the present study was to experimentally determine the effects of varying experimental parameters such as reaction duration, flammability and temperature change etc. on selected exothermic sleeves. The results were compared with thermodynamical simulations which were performed using the contents and the corresponding thermophysical properties of exothermic sleeves.

The interaction between a supersonic oxygen jet and liquid metal is a dominant factor affecting transport phenomena during the converter process. A systematic description of the interaction is of significant importance for a quantitative understanding of the transport phenomena. In this paper, cold model experiments and the corresponding numerical simulations were carried out to investigate the gas-slag-metal interaction inside an 80 t BOF converter. The effects of the operation parameters, such as inlet pressure, slag thickness and slag viscosity on the multiphase interaction have been studied. It has been found that the cavity profile is closely related to the operational conditionsOperational condition. The cavity depth increases with an increase in oxygen inlet pressure, whereas the cavity width is much less affected. The cavity profile is also clearly influenced by the thickness of the slag layer. The influence of slag viscosity on cavity profile is not significant under the present simulation conditions.

A field emission scanning electron microscope equipped with EBSD has been employed to evaluate the role of 0.013 wt% Nb on the evolution of the microstructure and texture of a novel thermomechanically processed low-alloy, medium-carbon steel. Specimens were subjected to hot-rolling with a total reduction of 80%, four passes in the recrystallization regime and four passes below the non-recrystallization temperature. Immediately after rolling, the strips were quenched to 420 °C and subsequently cooled slowly in a furnace to simulate strip coiling with transformation of austenite to bainite. The results showed that Nb microalloying results in a finer microstructure with a sharper texture when compared to an identical steel but without Nb. In addition, analysis of the retained austenite texture indicated that the main bcc texture components are the product transformed brass and copper components in the parent austenite.

Continuous casting of slabs is conducted with two successive steel flows: first from ladle to tundish, then from tundish to mold. There are certain process abnormalities related to ladle, tundish and mold. For example, change of submerged entry nozzle (SEN) is the one encountered during steel flow from tundish to mold. Tundish exchange is the abnormality taking place due to replacement of processed tundish with the new one at rest. Another example is the flow of steel from ladle to tundish without a ladle shroud. In this study, a statistical analysis was conducted related to the process abnormalities in slab casters of a steel plant. Slab surface defects observed in slab yard was incorporated in this analysis.

The difference on particle density causes mass and size segregation in the blast furnace throat, causing poor permeability in radial and circumferential direction. Understanding the effect of density difference on particle spatial-temporal distribution helps stabilize smooth operation and improve energy efficiency of blast furnace iron-making process. Based on discrete element method simulation, the influence of density difference on particle segregation behaviors is quantitatively characterized by the proposed method when the binary-sized particles are charged from parallel-type hopper of blast furnace. The results show that increasing the 4 mm particle density aggravates the mass segregation in circumferential and radial direction, and the maximum standard deviation of each ring reaches as great as 0.415. For size segregation, the difference on average mass fraction of small particle between center and edge ring decreases from 0.373 to 0.301. When increasing the 6 mm particle density, the similar particle segregation behaviors could be obtained.

The effects of B content and austenitizing temperature on hardenability and toughness of Cr–Mo alloy steel have been studied. The results show that the hardenability is deteriorated with increasing B content and austenitizing temperature. With increasing temperature, more and more B containing particles were dissolved in austenite and increase the amount of B atoms segregating at grain boundaries. Moreover, the coarsening grains reduce area of grain boundaries and also increase the amount of B atoms at unit grain boundary, excessive B atoms segregating at grain boundaries promotes precipitation of M₂B, which accelerates ferrite nucleation and reduces hardenability. The main elements in M₂B phase are Fe, Cr, Mo and B. The B atoms segregating at grain boundaries during austenitizing promote precipitation of M₂B during tempering which deteriorate toughness significantly.

In this paper the direct reduction melting separation-leaching process is investigated on recovering rare earth from rare earth Bayan Obo complex iron ore (REBOCIO). The REBOCIO was reduced and melting separated to produce iron nugget and rare-earth-rich slag at 1400 °C for 12 or 15 min. The RE₂O₃ is enriched into Ce_4.667(SiO₄)O or Ca₃Ce₂[(Si,P)₃O₄]₃F, which closely depend on chemical components, especially basic. The optimal acid-leaching parameters of rare earth elements from the rare earth slag are suggested as the hydrochloric acid concentration, the ratio of solid to liquid, leaching temperature, and the leaching time are 1 mol/L, 1:14, 50 °C and 120 min, respectively. The rare earth elements leaching efficiency are more than 95%. Adding of calcium CaCO₃ and sodium Na₂CO₃ in direct reduction process have great influence on leaching efficiency of thorium.

ReductionReduction roasting followed by magnetic separationMagnetic separation is an important method for treating laterite nickel ores. In this work, garnieriteGarnierite type laterite ore from Yunnan province in China was reduced by methaneMethane under different conditions followed by magnetic separationMagnetic separation to obtain the ferronickel concentrate. The phase and microstructure transformations of garnieriteGarnierite in the reductionReduction process were investigated using XRD and SEM-EDS. The experimental results showed that reductionReduction temperature from 873 to 1173 K had only a small effect on content and recovery of nickel and iron. The content and recovery of nickel and iron in the concentrates increased slightly with prolonging reductionReduction time. In addition, the nickel and iron content decreased with increasing methaneMethane concentration, but the recovery of nickel and iron increases. A decrease in the iron content and recovery were observed when the dosage of sodium sulfate varied from 5 to 20% at a temperature of 1073 K and reducing time of 90 min, while the nickel content and recovery gradually increased.

To solve the problem that the sintered liquid phase fluidity characteristic of low silica (w(SiO₂) < 3 wt%) and high silica (w(SiO₂) > 7 wt%)) iron ores were different from actual sintering production with using the common method based on w(CaO)/w(SiO₂), a new improved method based on n(Fe₂O₃)/n(CaO) was proposed. The differences between two methods for iron ore fluidity detection were studied. The results show that when the common method is used to detect the liquid phase fluidity, as the content of SiO₂ increased from 2.12 to 11.68 wt%, the amount of CaO addition augmented from 7.88 to 32.65 wt% and the corresponding fluidity index changed from 0 to 5.68. The fluidity index has a linearly positive correlation with the content of SiO₂. The improved method could significantly reduce the effect of the change of CaO addition on the fluidity characteristic of iron ore which caused by the difference of SiO₂.

Magnetite powder and coke powder were used as experimental materials and H₂ as reducing agent in a high temperature vacuum tube furnace. The change rules of magnetite powder (MP), mixed coke powder and magnetite powder (MCMP), and carbon coated magnetite powder (CCMP) in the process of reduction were studied. The samples were determined by field emission scanning electron microscopy and X-ray diffraction. The results show that, with the increase of reduction time, the reduction degree of magnetite powder is improved. Under the same reduction conditions, the addition of coke powder improves the reduction rate. Compared with MP, when the reduction time was 120 min, the reduction degree of MCMP was 30% greater; and the reduction degree of CCMP was 39% greater. The mixed grinding of magnetite powder and coke powder is a better way to add carbon. Under the same reduction conditions, compared with MCMP, the reduction degree of CCMP was 9% greater when the reduction time was 120 min. After the reduction of CCMP, the number of pores in the sample increased and the structure was loose. The results of this study have some reference value for improving the reduction rate of magnetite powder.

The basic characteristics of iron ore, including assimilation, fluidity, cohesive phase strength and the ability to produce calcium ferrite, are often used to evaluate the sintering properties of iron ore and guide the optimization of iron ore blending. Six kinds of common iron ore used in a steel company in China were selected in this work. The basic characteristics of the single iron ore and blended iron ores were studied, as well as the difference between weighted averages of basic characteristic index of single iron ores and the real value of basic characteristic index of blended iron ore under different ore blending ratios. The results shew that the liquid phase liquidity, cohesive phase strength and calcium ferrite formation ability had a significant linear positive correlation with SiO₂ content. The weighted average of basic characteristic index of single iron ore cannot fully reflect the actual blended iron ore properties. The optimization of the blending ratio can be achieved through the detection of the basic characteristics of the mixed iron ore, combined with the basic characteristics of iron ores.

In this work, research of reduction process was studied by means of rotary kiln (φ1.5 m × 15 m) process anatomy in order to provide fine guidance to large-scale operation. It was shown that the average reduction degree of 89.96% and metallization ratio of 85.15% were obtained at the highest temperature of 977 °C and total residence time of 90 min. The generation amount of metallic iron in section of temperature higher than 900 °C and lower than 900 °C was 34.15 and 56.38%, respectively. The section of lower temperature of 830–900 °C played an important role in formation of metallic iron, making it possible for mini-pellet to reduce quickly at lower temperature. Two main tasks were completed for mini-pellets in rotary kiln: the reduction of iron oxides in the range of 15.0–4.5 m as well as migration and beneficiation of metallic iron, facilitating the subsequent separation of iron and gangue minerals.

Metal carbides (MCs), especially transition metal carbides have attracted a lot of attentions due to their unique properties, such as high strength and hardness, good chemical and thermal stability. In this paper, a new route was proposed for preparing TiC nanoparticles directly from TiO₂/C precursor by using solid oxide membrane (SOM) technology in molten CaCl₂. The TiO₂/C pellet pressed under 8 MPa was used as the cathode, and a yttria-stabilized zirconia (YSZ) tube filled with carbon-saturated liquid tin was served as the anode. This process employs an inert SOM to separate the anodic reaction area from the molten electrolyte to control the electrolysis process. The electrochemical process was carried out in molten CaCl₂ at 1000 °C and 4.0 V from 0.5 to 4 h. The characteristics of the phase composition and morphology of the electrolysis products were investigated. The product electrolyzed was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS). The results show that TiC nanoparticles can be obtained directly from TiO₂/C mixture at 1000 °C, 4.0 V and for 4 h in molten CaCl₂ and the current efficiency is calculated to be 74.1%. In conclusion, we suggest that the SOM process is a promising environmentally friendly and low energy costs electrochemical method for the facile and controllable electrodeoxidation of MO_x/C precursors to micro/nanostructured MCs.

A mass of Al₂O₃ tends to form during the continuous casting process of high manganese high aluminum steel, and the properties of mould flux and the quality of slab are seriously affected. The dissolution rate of Al₂O₃ into the CaO–SiO₂–MgO–Al₂O₃–F−−Na₂O−Li₂O−BaO−B₂O₃ slag system has been investigated at 1573 K by employing rotating cylinder method. This paper focuses on the effect of Na₂O, Li₂O, B₂O₃, F−, Al₂O₃ contents and (CaO+BaO)/(Al₂O₃+SiO₂) ratio on the dissolution rate. Experimental results show that the dissolution rate increases with increasing Na₂O, Li₂O, B₂O₃ contents and decreasing Al₂O₃ content, among which Li₂O has the greatest effect on increasing dissolution rate; the dissolution rate increases with increasing F− content in slag A-1, but decreases with that in slag A-2; the dissolution rate increases with (CaO+BaO)/(Al₂O₃+SiO₂) ratio within the range from 0.91 to 1.31. The dissolution rate of Al₂O₃ into molten flux is mainly affected by the viscosity of the molten flux and the thermodynamic driving force.

In order to improve the oxidation resistance of Cr–Mo–V steel for high-speed railway brake discs, a higher Cr was added to the steel. Effect of temperature on the oxidation behavior of brake disc steel with different Cr contents was studied by OM, SEM and XRD. The results show that the oxidation curves at 500 °C obey a linear oxidation law in 0–2 h and 2–20 h, respectively. The oxide layer is thin and the oxidation products are Fe₂O₃ and Fe₃O₄. The oxidation curve at 700 °C follows a linear law within 2 h. With the oxidation time extending, the oxidation curves follow a parabolic law and the oxide layer becomes thicker. Moreover, the oxide layer is divided into two layers. The outer oxide layer is loose and is mainly Fe₂O₃, while the inner layer is denser and consists of FeO and FeCr₂O₄. The oxide layer thickness reduces and the oxidation resistance of the steel is improved with Cr content is increased.

Ti₅Si₃/TiC composite has been successfully prepared from the titanium-rich slag/SiO₂/C mixtures precursors by an electrochemical process. The electrochemical production process was carried out in molten CaCl₂ salt at 1000 °C and 3.8 V. A pressed cylindrical pellet of titanium-rich slag/SiO₂/C mixtures served as a cathode, and a solid oxide oxygen-ion-conducting membrane (SOM) tube filled with carbon-saturated liquid tin acted as an anode. The phase transformation of the cathode pellets during electrolysis process was investigated, the microstructure of the obtained products was characterized. It is found that the reaction pathways can be divided into three main stages during the electro-reduction process. The first stage is the generation of calcium compound, the second stage is the electrochemical reduction of the compound, and the third stage is the formation of Ti₅Si₃/TiC composite. The prepared Ti₅Si₃/TiC composite exhibits homogenous and nodular particle morphology.

The evolution of chemical composition, size, proportion, and morphology of the Al-Ti-Mg-O inclusionsAl-Ti-Mg-O inclusions during the steelmaking process of Interstitial FreeInterstitial free steel (IF) steel from the RH to the Continuous Casting (CC) slab were investigated by means of Auto-SEM. Results showed that many of Al₂O₃ and MgO-Al₂O₃ type inclusions are modified by TiO_x, while most of their shapes are irregular due to the high melting temperature. The composition evolutions and melting characteristics of Al-Ti-Mg-OAl-Ti-Mg-O inclusions inclusions under different contents of [Al], [Ti] and [Mg] were estimated by using thermodynamic software Factsage 7.0. Resulted showed that estimated results are in good agreement with the analysis results of industrial samples. Both the Ti alloying and spontaneous enrichment would make a high Ti concentration environment that was in favor of the TiO_x existence. Moreover, more TiO_x component can modify MgO-Al₂O₃ spine inclusion into inclusions with a lower melting temperature.

In order to obtain the solubility of carbon in vanadium-bearing hot metal, graphite powder is used for the carburization experiments. The other kinds of carburizers, namely low nitrogen carburizer, anthracite and coke are used for carburization of vanadium-bearing hot metal weighing 500 g at temperature of 1450, 1500 and 1550 °C respectively. Carbon increments of low nitrogen carburizer, anthracite and coke fall in descending order. It was found by comprehensive analysis that anthracite is the most cost-effective carburizer among three carburizers. Magnitude of apparent rate constant of carburization reactions is 10−4 s−1. It is found that the carburization rate increase with temperature.

Iron precipitation occupies a vital position in the metallurgy industry, especially for treating iron-bearing sphalerite in hydrometallurgical processes. This paper emphasizes techniques for removing iron from high-iron sphalerite via hematite precipitation, and describes the results of research performed to examine ferrous oxydrolysis and precipitation. The behavior and mechanism of conversion between the iron phase and hematite residue at elevated temperature under pressure is ascertained by investigating the dissolving characteristic and thermodynamics stable area of hematite at sulfate system. The results show hematite precipitation went through the process of crystallization, dissolve, oxidation and precipitation of ferrous sulfate, and the overall iron precipitation was determined to be controlled by the rate of ferric sulphate hydrolysis rather than the oxidation of ferrous sulphate or the re-dissolution of ferrous sulphate crystals, or the transformation of basic ferric sulphate.

In this paper, the change of crystallization rate, dendrite arm spacing and dendrite width of mold flux with various magnetic field conditions were studied by experiment. Having found that the crystallization ratio of mold flux increased from 33 to 96.6%, the dendrite arm spacing decreased from 72.47 to 38.02 μm, the dendrite width decreased from 48.47 to 27.02 μm while the magnetic field frequency (f) equaled to 8 Hz and its strength (B) increased from 0 to 30 mT. The crystallization ratio of the mold flux increased from 91.9 to 96.1%, the dendrite arm spacing decreased from 60.53 to 28.08 μm,the dendrite width decreased from 42.53 to 24.08 μm when B equaled to 20 mT and f increased from 6 to 12 Hz. However, the XRD analysis indicated that the phase types of the mold flux under the experimental conditions did not transform. Results showed that an alternating magnetic field can promote the crystallization of mold flux and refine grain structure.

Adding limestone directly into converter is considered to be favorable to energy conservation and emission reduction by transferring the decomposition reaction of limestone from the shaft or rotary kiln to the converter. In this paper, the kinetics of limestone decomposing in early converter slag was studied at 1300–1400 °C, and the effects of slag temperature and stirring speed introduced to the slag bath were examined. The kinetic results based on shrinking core model analysis showed that the limestone decomposition was a mixed rate control of chemical reaction and heat conduction through the lime layer, which could be promoted at higher slag temperature by supplying more heat to the converter bath. In addition, the chemical reaction rate constant and effective thermal conductivity were determined.

A mathematical modelMathematical model of converterConverter slagging and steelmakingSteelmaking process by replacing part of lime with limestone is established. The rate equations of oxidation reactions and lime dissolution in converterConverter under the limestone substitution proportionLimestone substitution proportion increasing from 25 to 50% can be obtained and the effects of limestone substitution proportionLimestone substitution proportion on the variations of the composition of hot metal, slag and converterConverter gas during the steelmakingSteelmaking process are investigated. In the process of converterConverter slagging and steelmakingSteelmaking by replacing part of lime with limestone, increasing the hot metal temperature and the lance height could be favor to increase the content of FeO in the slag and accelerate the limestone decomposition and dissolution. With the limestone substitution proportionLimestone substitution proportion increasing from 25 to 50%, the maximum of oxygen supply ratio increases from 10.7 to 19.7% and the temperature drop of converterConverter bath is 8–60 °C.

As a shortage of information technology support, steel plant is unable to real-time tracking production cost of each working procedure, and can’t form the information feedback in time. Information integration technology for dynamic monitoring becomes a development trend of process control in advanced iron and steel enterprise. The paper based on the characteristics of EAF steelmaking process and requirements build the digital platform and process guidance model, which is designed to solve for smelting composition control, cost control, and optimizing guide in EAF steelmaking process. The model is including: data acquisition module, cost monitoring and calculation module, EAF endpoint carbon control module, alloy material optimization module, component monitoring and forecast module, process guidance module, data maintenance and query module.

In practical production process, the average of silicon content in hot metal (HM) of COREX process (the average is 1.58%) is obviously higher than that in blast furnace (the value is below 0.6%), which leads to an increase in the cost of steelmaking. In this work, the factors affecting and impact mechanism of silicon content in HM were investigated by statistical analysis using actual operating data. The analysis indicates that the fuel rate, binary basicity of slag and the temperature of HM are positively correlated with the silicon content, while the sulfur content of HM and binary basicity of burden are negatively correlated with the silicon content. On this basis, a back propagation neural network was developed to predict and control the silicon content in HM. All the findings of this work are useful for guiding and optimizing the COREX operation.

The influence of bottom blowing a CO₂–O₂ mixture on the bath temperature of a vanadium extraction converter was studied by using the characteristics of CO₂ with weak oxidizing. It was studied in two aspects: oxygen content and temperature. The experiments showed, when the ratio of the mixture of CO₂–O₂ was 2:8 at 1300 °C, the bottom blowing of the converter inhibited the heating up of the hot metal, thus keeping the temperature below the carbon vanadium transition temperature. At 1360 °C, the sensible heat absorption by CO₂ was 1.44 times that absorbed by O₂ per mole. Meanwhile, at 1300 °C, 20% CO₂ released the chemical heat of 13.58 kJ. So with the increase of the CO₂ ratio, the bath temperature was reduced. The research showed that the bottom blowing of a CO₂–O₂ mixture had an advantageous effect by decreasing the temperature of the vanadium extraction converter.

Grain size and porosity of the produced lime from limestone in early converter slag and the influence of slag temperature in the range of 1300–1400 °C were investigated. The experimental results showed that both the grain size and porosity of the produced lime depended significantly on the slag temperature. After the complete decomposition time of limestone, grain size and porosity changed under the role of CaO grain growth. Grain size evolved sharply with slag temperature, which was illustrated by an analysis on the relationship between grain size and reaction time. Meanwhile, higher porosity was reached at 1400 °C due to the higher concentration gradient of CO₂ between the reaction interface and slag bulk. A proposal to obtain the produced lime with finer grain size and higher porosity was given in this paper.

In order to reduce the Al₂O₃ inclusions in 50Cr5MoV roller steel produced by EBT-LF-VD-VC process in a steelmaking plant, the LF refining slag was optimized and the influence of optimized slags with different w(CaO)/w(Al₂O₃) ratios on reducing inclusions were investigated in the laboratory. The results showed that, when w(CaO) = 50–55%, w(Al₂O₃) = 25–30% and w(CaO)/w(Al₂O₃) = 1.5–2.0, this optimized slag can not only reduce massive Al₂O₃ come from aluminium deoxidation, but also change the remain into plastic CaO-MgO-Al₂O₃ spherical compound inclusions with 1–5 μm diameter, the harm on the performance of the steel was minimized.

The thermogravimetric method was selected for investigating the evaporation of Sb₂S₃ in the pressure range of 50–300 Pa and in the temperature range of 823–1123 K, the gas phase diffusion was the rate-determining step for Sb₂S₃. The volatilization rate was related to the temperature and pressure, that the logarithm of volatilization rate yielded a line with the reciprocal of temperature and pressure. The volatilization rate for Sb₂S₃ was between 0–0.023 g·cm−2·s. The apparent activation energy was between 65.8 and 60.6 kJ/mol.

The effects of ZrO₂, Y₂O₃ and Sc₂O₃, which are transition metal oxides, on the melting temperature, viscosity at 1300 °C, and break temperature of three mold fluxesMold flux (two weak-reactive type and one non-reactive type) designed for the high manganese and high aluminum steels, and one another conventional CaO-SiO₂ based mold flux is studied. The results indicate that the melting temperature and viscosity increases slightly, and the break temperature increases dramatically with the addition of ZrO₂, Y₂O₃ and Sc₂O₃ content in the conventional CaO-SiO₂ based mold fluxMold flux system. While, the addition of ZrO₂, Y₂O₃ and Sc₂O₃ in the weak-reactive or non-reactive mold fluxMold flux systems has a negligible influence on the melting temperature, viscosity and break temperature, suggesting that these transition metal oxides are possible to regulate radiation heat transfer without changing the basic properties of mold fluxesMold flux.

The roasting is the key step for the extraction of vanadium from vanadium slag by calcification roasting–acid leaching process. In this study, thermogravimetric analysis and kinetic study of vanadium slag in the presence of calcium oxide was investigated. The maximum oxidation degree was slightly increased by increasing temperature from 700 to 900 °C then almost unchanged further increasing temperature to 1000 °C. The reaction mechanism was analyzed through both Sharp method and ln-ln method. Results showed that the mechanism the reaction in the α range of 0.1–0.8 corresponded to the random nucleation and subsequent growth, as represented as (G(α) = [−ln(1−α)]1/3 = kt. The apparent activation energy was calculated to be 3.5 kJ/mol according to Arrhenius equation.

Mould flux is a vital functional material which is based on silicate including flux and framework material. The effects of magnetic field intensity and frequency on viscosity of mould flux were tested by rotational viscosity tester and a measurement device for electromagnetic characteristics of mould flux viscosity under high temperature conditions. The results show that: with the magnetic field intensity rising (0–30 mT), the viscosity of mould flux increases by 1.3–1.8 P. With the frequency rising (6–12 Hz), the viscosity of mould flux is increased by 1.2–1.4 P. When the binary basicity is 1.08, the viscous flow activation energy increases with the increase of the magnetic field intensity and frequency. It can be the main reason for the increase of mould flux viscosity that the electromagnetic forces disrupt the ordered structure of mould flux and make the ion migration rate increase.

In this study, microwave heating was used to dry the nickel laterite which contains plenty of free water, crystal water and hydroxy water. The results showed that compared with the conventional drying process, the microwave drying greatly improved the drying efficiency of nickel laterite. The whole microwave drying process can be divided into three stages according to the drying rates, namely, the rising stage, stable stage and declining stage. The effects of microwave power output and particle size were also studied in the range of 0.8–2.0 KW microwave power and 3–6 cm of particle size. The results showed that the drying time significantly decreased with the increase of microwave power and decrease of particle size. The phases transition of the sample during the microwave drying process were also discussed.

The COREX process, which is considered to be able to replace the blast furnace, still has some gaps to reach the designed productivity. The metallization degree is regarded as one of the limitations of the COREX process. In the present work, several parameters affecting the metallization degree of direct reduced iron (DRI) are analysed by SPSS software (Statistical Product and Service Solution). Melting rate, oxidation degree of reducing gas, oxidation degree of top gas, top gas consumption per ton of burden, temperature of reducing gas, and burden distribution index are confirmed as the main factors affecting metallization degree. Based on this, a linear equation has been developed for predicting metallization degree. Additionally, improving the melter gasifier vault temperature appropriately, increasing the proportion of high volatile matter coal, and optimizing the type and particle size of iron ore and the pattern of burden distribution have been shown to improve the metallization degree.

A new microwave roasting technology for the removal of Cl from zinc oxide dust is proposed in this paper. The effect of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The experimental results show that zinc oxide dust dechlorination rate can reach more than 95.66% and meet the requirements of wet smelting electrolysis when controlling the stirring speed of 60 r/min,roasting temperature of 650 ℃, holding time of 30 min. In addition, the effect of roasting temperature and holding time on removal efficiency of Cl was most significant. As a result, the Cl content was decreased without the risk of pollution. This makes it as a good choice for a more ecological treatment of zinc secondary resources.

The viscous behavior of molten slags has played an essential role in determining the performance and productivity of the ironmaking process. In this paper, the viscosity and free running temperature in CaO-SiO₂-Al₂O₃-9 mass%MgO-TiO₂ slag has been measured at different content of Al₂O₃ and Al₂O₃/SiO₂ ratio. In addition, the slags viscous activation energy has also been calculated. The results show that the TiO₂ as a basic oxide content from 1 to 5 mass% can reduce the viscosity and free running temperature, and moderate content of TiO₂ in high alumina blast furnace slag remains effective for reducing viscous activation energy and free running temperature.

The rotary hearth furnace iron nugget process is in line with China’s energy and resource condition. It has the advantages of short reaction time and high quality iron nugget. The fundamental study on the novel ironmaking process is meaningful. Based on CaO-SiO₂-Al₂O₃-FeO quaternary slag system, the effects of slag basicity and Al₂O₃ content on the melting of slag were studied. Using the iron concentrate as raw material, the effects of different slag basicity and Al₂O₃ content on the reduction and melting separation behaviors of carbon composite pellets, such as the starting temperature of melting separation and the morphology of melting separation were studied. Then, the relationship between the properties of slag and melting separation quality was established, which could provide standard for the selection of iron ore for the rotary hearth furnace iron nugget process.

Coke plays an important role on the actual blast furnace production (BF), and its quality significantly influences the BF ironmaking process. In this study, the effects of physical properties, chemical composition and high-temperature properties of coke on main technical indexes of blast furnace were investigated. Some coke indexes were defined to evaluate the coke quality. The main technical indexes of BF include production, quality of HM, and fuel consumption. The quantitative relationship between coke quality and main technical indexes of BF were obtained after a series of statistical analysis. What’s more, the effect of these coke quality indexes on blast furnace smelting process was also explored, and all the relationships obtained from the analysis will provide a theoretical basis for the appropriate use of coke in blast furnace. The most reasonable range of coke quality indexes can be determined combining with the actual production as well.

The kinetics study of blast furnace dust (BFD) recycling with flash reduction process at high temperature has been carried out using a high temperature drop tube furnace in laboratory scale. A combination characterization methods of chemical titration and SEM-EDS were used to track the reduction kinetics. The experiments using CO and CO₂ mixtures with range of CO/CO₂ (1:0, 1:1) at different temperature (1623–1723 K) and at different reduction time (1560–2340 ms) were conducted. It was found that the reduction degree increases with the increase of temperature and reduction time as well as CO concentration. The carbon contained in the original BFD has weak influence on the reduction potential in the form of gasification. The unreacted core model was adopted based on the observation of the cross section and the measurement of iron element content, the effective diffusion coefficient and reaction rate constant were determined and the rate controlling step was also analyzed.

To reduce coke consumption in blast furnace ironmaking, this study proposed a new method of applying iron-coke briquette prepared using hematite powder and pulverized coal to protect coke in BF iron making. Results showed that, with a ratio of hematite to coal of 2.0, the iron-coke briquette could obtain a satisfying compressive strength of more than 1500 N both before gasification and after being gasified by CO₂ for 1 h. The activation energy of the iron-coke briquette was 93–135 kJ/mol, which is lower than the coke and therefore could protect the coke in BF. The agglomeration and stratification of iron particles occur in the course of iron-coke briquette gasification and is beneficial to the improvement of the iron-coke briquette strength.

The microstructure and mechanical strength variations of chromite pellets preheated and roasted in air were studied systematically. The results show that the chromite (Fe,Mg)(Cr,Fe,Al)₂O₄ is oxidized to magnesium-rich (Mg,Fe)(Cr,Fe,Al)₂O₄ and ferrochromium complex oxide (Cr,Fe,Al)₂O₃ in the preheating process over 500 °C. When the temperature is higher than 1000 °C, the new phase (Cr,Fe,Al)₂O₃ is formed, which is mainly distributed in the outer layer of a single chromite particle. Inner the particles there are acicular (Cr,Fe,Al)₂O₃ and unoxidized (Fe,Mg)(Cr,Fe,Al)₂O₄, which forming an interwoven structure together. The oxidation rates of pellets can reach to superior limits in 20 min. With the temperature increasing from 950 to 1300 °C, the mechanical strength and oxidized rates increase to varying degrees correspondingly.

Spraying technology on sintering surface bed after ignition has become a hot research topic, with the purpose of achieving energy-saving, emission reduction and improvement of sintering indexes. In this paper spraying steam technology was researched from theory, experiment and practice. First of all, from the thermodynamic and kinetic analysis, the mechanism of sintering surface spraying steam was analyzed and its advantageous effect was confirmed. Based on this, sintering pot test and commercial trial were carried out respectively. The results shown that spraying steam is beneficial for increasing coke combustion efficiency with improving CO₂/(CO+CO₂) in the exhaust gas from 80% to about 85% level, through decreasing CO content of flue gas by more than 1000–2000 ppm. There was a suitable spraying amount to improve the quality of the sinter, and the spraying position of the steam cannot be excessively front and rear. Due to the low steam pressure (1 kg) and temperature (about 100 °C) compared with industrial steam (3 kg and 130 °C, respectively), the sinter quality such as yield index was affected by spraying steam in sintering pot test to a certain extent, and proper spraying amount (0.008 m3, 50 kg sinter) in sinter pot test is far smaller than application amount in commercial trial (2t/h). It is thought that suitable spraying steam parameters has a comprehensive effect of energy saving and quality improvement.

Grate bar is the key component of the sinter machine used for loading sinter and raw materials. Bar channels are sometimes bonded into blocks, which affects the service life of bar, and more importantly reduces the effective ventilation area of the sintering, affecting the normal production of sintering, resulting in unstable negative pressure, higher electricity consumption, and lower production and quality of sinter. In order to solve this problem, the systematic study was done on bonding materials of bars, based on which bonding mechanism of sinter grate bars was obtained. The KCl is an important characterization of bonding. Control standard of blending ore that prevents bonding is K₂O content below 0.06% and Cl content below 0.05%.

In view of the traditional evaluation index of sintering basic characteristics ignoring process information, several high temperature characteristic numbers, which contain process information, were used to evaluate the sintering basic characteristics more comprehensively in this paper. The evaluation model of iron ore properties was established based on the high temperature characteristic numbers with employing fuzzy mathematics. Then, with the constraint of sinter properties and the raw materials, the ore blending model was built, whose target was to obtain the lowest cost and the best sinter properties. A multi-objective fuzzy linear programming was used to solve the model in order to get the best ore matching schemes. The ore blending model was then applied to the practical production, which was proved to be dependable.

Characteristics of the gas-solid reduction reaction between iron ore sinter and carbon monoxide (CO) gas at 1273 K were studied with thermogravimetric analyzer. The microstructure, mineral compositions and porosity of sample were investigated prior to reduction, in the 30% reduced sample, in the 70% reduced sample, and in the fully reduced sample. At the reduction degree of 30%, the hematite and calcium ferrite was reduced to 44.4 and 60.4% respectively. At the reduction degree of 70%, all the hematite, calcium ferrite and magnetite were reduced to metal iron, only 36% wustite was left in the core area. The reduction reaction began with the loose structures and spread to the nearby area. In the area of micro-pores, the reducing gas can easily diffuse to the reaction interface to proceed the reduction reaction effectively. So increasing the content of micro-pores is an effective way to improve the reducibility of the sinter.

Molybdenum is a refractory metal that has melting point at ~2610 °C. It has high modulus of elasticity even at elevated temperatures. Almost 80% of molybdenum is used as alloying element for ferromolybdenum. When added to steel, molybdenum increases strength hardenability, toughness, elevated temperature strength and corrosion resistance. Molybdenum metal is produced from its sulphide ore through oxidizing roasting of molybdenite to produce molybdenum trioxide and then purification of molybdenum trioxide and hydrogen reduction of molybdenum trioxide. In this study molybdenite (MoS₂) is roasted in both chamber type furnace and rotary kiln under different conditions such as different temperatures and air atmospheres. Samples were taken off during the roasting process to analyze the sulphur content. After roasting experiments a kinetic study was carried out. Activation energies were calculated for both conditions and compared to each other. The raw materials and the products were characterized by using XRD and AAS.

In this paper, study on the influences of different Ti-bearing materials on MgO-bearing pellets metallurgical properties was carried out. The results show that, pellets compression strength will decrease while using ilmenite. However, TiO₂ reagents help to improve pellets compression strength. The reduction swelling decreases while using TiO₂ reagents, but different ilmenites have diverse impacts on the reduction swelling. Pellets compression strength will decrease and reduction swelling will be improved while adding magnesium additives. In order to produce qualified Magnesium-Titanium bearing pellets, the firing temperature should be no less than 1270 ℃.

Printed circuit boards (PCBs) contain plenty of toxic substances as well as valuable metals (e.g. Pb and Sn). In this study, supergravity as a novel technology was used to separate and recover different mass ratios (Pb/Sn) of Pb-Sn alloys from PCBs. In a supergravity field, liquid metal phase can permeate from the solid particles, and based on this, 200, 280 and 400 °C were selected to separate Pb and Sn from PCBs. The results showed that the gravity coefficient only affected the Pb-Sn alloy weight, and did not change the mass ratio of Pb/Sn. With the increase of gravity coefficient, the recovery values of Pb and Sn were increased. In the separation process, under the gravity coefficient of 1000 and separation time of 2 min, the recovery values of Pb were 33.13, 38.86 and 50.48% at the temperature of 200, 280 and 400 °C, respectively, and the recovery values of Sn were 23.31, 32.57, and 40.81%, respectively, and the mass ratios of Pb/Sn in the Pb-Sn alloys were 0.55, 0.40 and 0.64, respectively. This provided a new approach to recycle Pb and Sn from PCBs.

Due to complicated structure and composition of high-phosphorus iron oreHigh-phosphorus iron ore, pure substances were used to simulate the chemical composition of high-phosphorus iron oreHigh-phosphorus iron ore to study the reaction of fluorapatiteFluorapatite at different temperatures and effect of additivesAdditive. The gasification process of P during carbothermic reduction process was investigated using a quadrupole mass spectrometer gas analysis. It is found fluorapatiteFluorapatite was reduced to phosphorus which diffused into iron and gas phase. From the gas analysis, it was observed that PO and P gas species were vaporized around 800 °C. As the reduction temperature increased, the diffusion of phosphorus into iron was enhanced. The presence of Ca(OH)₂ as additivesAdditive not only promoted the reduction of iron oxide, but also decreased the degree of fluorapatiteFluorapatite reaction to inhibit P into iron.

In order to make full use of the chromium-bearing vanadium titanium magnetite with chromium, a new process of “direct reduction-electric furnace smelting separation” has been developed for recovering the iron, vanadium, titanium and chromium in recent years. In this paper, FactSage, one of the most frequently-used thermodynamic calculation software, was used to calculate the reduction degree of Fe, V and Cr with different n_C/n_O (mole ratio of carbon and oxygen). It was found that the suitable operating conditions of direct reduction process were n_C/n_O > 1.07 and T > 1473 K. In addition, the direct reduction experiment of Hongge vanadium titanium magnetite was carried out and the obtained samples after direct reduction were analyzed by XRD and chemical composition. The result shows that the metallization rate of carbon-containing pellet is nearly 90%.