REWAS 2022: Developing Tomorrow’s Technical Cycles (Volume I)

For more than a century, aluminumAluminum has played a major role in providing high-strength, low-weight mass reduction solutions to all forms of efficient transportation. As companies, governments, and consumers increasingly prioritize responsible environmental stewardship, the aluminum industry is collaborating to define the research and development goals necessary to ensure a sustainable future. At the helm of that collaboration is The Aluminum Association, its member companies, industry colleagues, and automotiveAutomotive customer base. Achieving measurable and impactful goals over the next decade will enable manufacturers to not only optimize aluminum applications in future passenger vehicles, but also maximize the value of the aluminumAluminum content in those vehicles as they are removed from service. The Aluminum Association’s new AutomotiveAutomotive Aluminum Roadmap outlines strategic priorities while recognizing how the changing landscape of mobility is increasingly connected and electric. Within that landscape, this manuscript and related presentation detail the reasons why aluminum is the fastest growing automotive materialMaterials, in what applications aluminumAluminum content continues increasing its share, and the impact consumer demand and government regulations have in directing automobile producers away from conventional internal combustion engines to increasingly electrified fleets.

A sustainable energy future is axiomatically an electric future whose realization depends in part upon electrochemical innovations. Two examples are stationary energy storage and carbon-free steelmaking. Grid-scale electricity storage not only treats the intermittency of renewable electric power generation (wind and solar) but also confers resilience to today’s grid. For example, the liquid metal battery provides colossal power capability on demand and long service lifetime at requisite low cost. In 2019, worldwide steel production, 1.869 billion tonnes, generated 9% of total anthropogenic CO2 emissions. As an example of novel approaches in this sector, molten oxide electrolysis represents an environmentally sound alternative to today’s carbon-intensive thermochemical process which produces an average 1.83 tonnes CO2 per tonne of steel. In the narratives of both of these emerging technologies, there are lessons more broadly applicable to innovation: pose the right question, engage young minds (not experts), establish a creative culture, and invent inventors.

The objective of this paper is to demonstrate the use of natural language processing tools to map the propensity of usage of specific solventsSolvent used for the fabrication of different perovskitePerovskite photovoltaic (PV) systems. This article focuses on implementing contextual natural language processing (NLP)Natural Language Processing (NLP) tool to identify different chemicals that appear in the synthesis of perovskite solar cells. This information is linked to the known level of hazard of those solvents. This work serves to demonstrate how by harnessing the tools of informatics, in this case NLP, offers a powerful framework to guide environmentally conscious selection of chemicals used in the manufacturing of perovskitePerovskite solar cells.

The physicochemical propertiesPhysiochemical properties, viscosityViscosity, density, and surface tensionSurface tension, are critical properties of liquid metals and alloys. These properties are needed for thermodynamics, solidification modelling, and materials properties databases. The discharge crucible method (DC) developed in 2003 has been used to measure and report these properties for a wide range of liquid metals and alloys, including Sb, Sn, Zn, Al, Al–Cu, Sb–Sn, Sn–Ag, and AZ91D. The results are compared with published data and models that are proposed to predict these property values. This method is based on a mathematical formulation that predicts the velocity of a stream draining from an orifice. The viscous losses are calculated using a discharge coefficient equation, and the gas–liquid surface tensionSurface tension is determined using the Young–Laplace overpressure induced in the jet. The model and experiments will be described along with the effect of nozzle shapes on the distribution of forces in the DC method, including the effect of wetting of the orifice. The aim is to define the optimal nozzle design for a good distribution of forces throughout a draining experiment.

The copperCopper industry is striving to achieve sustainable developments while providing copperCopper as an essential raw material for today’s electrical/electronic society. Copper resources are limited, and copperCopper production requires a large amount of energy, especially for ore processing. Meanwhile, the major end-product manufacturers are required to limit their carbon footprint of copperCopper material, especially by using recycled copper. Whether recycled copper alloys have undergone a life cycle assessment (LCA) at the time of manufacture is doubtful. Furthermore, no metal material can be recycled without a primary metal. If the required amount of copper alloy can be covered by recycled copper, an LCA evaluation of the recyclingRecycling process will be sufficient, but this situation seems unreasonable given the recent growth in copperCopper consumption. Therefore, in this presentation, I propose an integrated LCA evaluation that includes copper ore extraction, smelting, and recyclingRecycling processes.

SMS group is innovating and developing future solutions in the non-ferrous metals sector to enable the circular economy (CE). The recycling of valuable metals is one of the key enablers for the CE. SMS group offers numerous recycling solutions to recovery metals and other valuable substances from metal scraps, electronic wastesElectronic waste, batteries, catalysts, etc., which are based on a sequence of pyro- and/or hydrometallurgical process steps. This paper shares experiences on recently commissioned solutions, for example, Aurus in Russia.

Tungsten (W) is one of the most important metals in various industries, particularly in the machining industry. At least 60% of W is consumed in cemented carbide or super-hard alloys in Japan and the USA. The major recyclingRecycling method for cemented carbides is the hydrometallurgical process combined with the roasting step, which oxidizes W in scrap into tungsten oxide. However, this conventional process requires repetition of roasting and dissolution in some cases, which makes the process costly and inefficient. In contrast, the molten salt process has specific advantages in terms of processing rate and simplicity. In this study, the recyclingRecycling processes for W using molten salt are reviewed. Subsequently, our new recyclingRecycling process using molten hydroxide is introduced, and recent data on this process discussed.

The recovery of resources from processing urbanUrban waste and industrial waste streams is essential to creating a sustainableSustainable recycling society. The implementation of the ISASMELT™ISASMELT™ Top Submerged Lance (TSL)Top Submerged Lance (TSL) technology for the retrieval of metals, and the capture of energy has been applied in the real world for over 20 years. The ISASMELT™ furnace is highly suited to treat these complex waste streams, with their varying compositions and dimensions, due to the flexibility and adaptability of the technology. The conditions in the furnace are tightly controlled to ensure the desired products and compositions are achieved. The turbulent, high temperature melt is capable of destroying hazardous chemicals. The slag generated can be used or stored without causing further pollution. This paper describes how existing and future ISASMELT™ISASMELT™ operators can leverage the technology to supplement their feed supply and recover valuable materials from an increasing range of urbanUrban waste and industrial waste streams.

SilverSilver (Ag) is extensivelyPrecious metal used in manufacturing of electronic goods due to its low cost and conductivity. In view of the escalating demand, stringent, environment rules, and limited sources of Ag, the present paper is focused on the development of hydrometallurgicalHydrometallurgy process flow-sheet to extract Ag from scrap computer keyboards. These keyboards contain ~0.4% of Ag. Initially, keyboards were dismantled to separate the Mylar sheets scontaining Ag. The same were pyrolyzed at 300 °C for 2 h to get enriched metallic part. About 99.99% Ag was leached using 2 M HNO3 at 60 °C within 30 min in close and proper condensed system. Separation techniques (precipitation/cementation) could be used to obtain pure Ag salt/metal. Based on the laboratory-scale experiments, the process flow-sheet developed is economical, eco-friendly, and has potential to be translated to industry for commercial exploitation after scale up/pilot trial.

The recyclingRecycling and secondary recovery of titaniumTitanium (Ti) scraps requires the direct removal of oxygen (O) from the Ti scraps. Although several deoxidation techniques for Ti have been developed, the strong affinity between Ti and O limits their cost-effectiveness. In this study, we develop a new deoxidation process for Ti using cerium (Ce) metal, which is the most abundant and cost-effective rare earth element. Thermodynamic analysis suggests that the deoxidation through the formation of Ce oxyhalides in halide fluxes containing Ce ions enables the production of Ti with extremely low O concentrations. We experimentally demonstrate that the formation reaction of CeOCl with Ce metal can deoxidize Ti metal and produce highly pure Ti with 100 mass ppm O or below, which is lower than the O concentration of the virgin Ti produced by the Kroll process. This deoxidation process with Ce metal enables the recyclingRecycling and secondary recovery of Ti scraps contaminated with O.

This article analyses BangladeshBangladesh export–import data to quantify historically generated e-wasteE-waste from four types of discarded electronic devices (mobile phones, TVs, tablets, and computers/laptops) and uses the trends to predict the generation of e-waste from these devices up to 2030. From this data, together with estimated redundancy rates, printed circuit board (PCB) masses, metal content, and value based on characterisation of indicative samples, the potential value of e-wasteE-waste was evaluated. Through processing the PCBs in BangladeshBangladesh, metals including Cu, Ag, Au, Pd, and Sn worth more than US$2.4 billion till 2020 could be recovered. This value could reach US$7 billion when forecasted to 2030. The potential value varies mainly with the fluctuating metal prices in the international market.

To recover rare earth elements (REEs)REE magnet from Nd–Fe–B magnets, a variety of hydrometallurgical processes have been developed, and among them, caustic digestionCaustic digestion-acid leachingLeaching is the most promising. Through the caustic digestion, Nd and Fe in the magnet alloy could be converted into Nd(OH)3 and Fe3O4, respectively, and they were easily recovered in the following acid leaching step. To remove iron from REE leach liquor, it was essential to precipitate iron after the acid leaching, and it consumed an amount of chemical like lime. So, to solve the aforementioned problem, a new green process was developed, lowering iron content in leach liquor; through an oxidative roastingRoasting of the digested product prior to the acid leaching, iron dissolution was considerably decreased. The digested powder was roasted at 350–450 °C, and the product was leached in 0.5 M HCl. The final leach liquor contained ca. 17 g/L Nd and ca. 330 mg/L Fe.

The electric mobility and the energy transition rely on the development of performant energy storage devices such as fuel cells and Lithium-ion batteries. It is expected a huge increase of Lithium-ion batteryLithium-ion battery production in the next years due to the increase of electric vehicles on the market. These batteries will have to be recycled in the next ten years. It is therefore of great importance to develop the recyclingRecycling sector of Lithium-ion batteriesLithium-ion battery. Among other, the search for efficient, cheap, and environmentally friendly processes for recyclingRecycling Lithium-ion batteriesLithium-ion battery must be prioritized under the impulsion of governmental regulations. HydrometallurgyHydrometallurgy will replace the pyrometallurgical processes in a closed loop recyclingRecycling strategy to produce metallic salts from spent Lithium-ion batteriesLithium-ion battery that could be reused to manufacture new batteries. This paper gives a brief overview of the key elements for designing appropriate Lithium-ion battery recyclingRecycling processes.

Increasing demand for critical metallic elements for sustainability applications motivates new approaches in primary and secondary production to handle falling ore grades and increasingly convoluted recyclingRecycling streams. Separation of elements in distinct phases is generally less energy intensive than separation of elements substituted within a single phase, a phenomenon referred to in primary extraction as the “mineralogical barrierMineralogical barrier”. Engineered materials leverage element substitution within single phase solutions to achieve target material performance. This results in large energy requirements during end-of-life recycling to selectively recover, via chemical separation, the target elements contained within a single phase. Herein, we present selective sulfidationSulfidation as a novel, pyrometallurgical pretreatment to selectively partition target elements from a single phase into distinct, separate phases. We find such approach may support more competitive physical separationPhysical separation of difficult to isolate elements that previously required separation via complete hydrometallurgical dissolution and aqueous-organic liquid–liquid solvent extraction. We demonstrate selective sulfidationSulfidation as applied to end-of-life magnet, battery, and copper slagSlag recycling as a means to shift the burden of selective separation from chemical to physical processes.

Silicon kerf residueSilicon kerf residue is generated during the wafering process of pure silicon in the photovoltaic value chain. The generated by-productUtilization of by-products has a high volume, and the particle size is typically below 1 μm. Although the fine particles are partly oxidized, the material may be beneficial in different metallurgical applications such as grain refining and alloy composition adjustments. This work studies the dissolutionMelting and dissolution of silicon kerf behavior of silicon kerf in low alloy steelLow alloy steels melts with the aim to upcycle the kerf material in the steel industry for different purposes. In this study, a steel alloy and the kerf residue were melted (at 1580 °C) in an alumina crucible placed in an induction furnace. The amount of added kerf residue was varied. The behavior of the particles in the solidified alloy was characterized by using an optical microscope, electron probe microscope (EPMA), and wavelength-dispersive X-ray spectroscopy (WDS) in order to study the dissolutionMelting and dissolution of silicon kerf behavior of the Si-kerf residue in the steel.

The importance of lithium in modern industry is proven by a staggering triplication of the market for Li-based batteries, valued at $30b in 2017 and expected to reach $100b by 2025. Lithium is used as nanoparticles, particularly for batteries and electronics applications. Presently, lithium nanoparticles are manufactured using induction thermal plasma and other energy-demanding technologies. Furthermore, lithium is mined using significant volumes of water in areas such as South America, where aquifers are facing an ever-growing pollution from over-mining and agriculture, affecting the provision of clean and safe drinking water. We propose a switch in mining and manufacturing methods through the use of phytomining in ancient mine locations, to foster economic sustainability in areas affected by unemployment while maintaining the historic splendour of these sites. This paper will focus on the report of preliminary experiments using Agrostis Tenuis as hyperaccumulator for lithium and the characterisation of the biomass to assess its metal collecting behaviour. Our experiments have proven that in such areas, the amount of lithium (~1000 ppm) present in the sludges derived from mine adits can be recovered by autochthonous grasses (~20% per harvest) and transformed into re-usable nanoparticles using low-energy bio-synthesis.

An innovative electrochemical process to separate lithium, nickel, manganese, and cobalt using a three-stage electrodialysisElectrodialysis with the addition of ethylenediaminetetraacetic acidEthylenediaminetetraacetic Acid (EDTA) (EDTA) is proposed. Before the electrodialysis experiment, ultraviolet–visible spectroscopyUltraviolet-visible spectroscopy is used to study the complexation behavior of EDTA with four different metals. During the electrodialysis experiment, a synthetic solution mixed with a stoichiometric ratio of EDTA to the target metal is supplied to a lab-scale electrodialysis stack, in which nickel is separated in the first stage, cobalt is separated in the second stage, and manganese is separated from lithium in the third stage. The results reveal that the concept of separating four different metals in a multi-metallic system using the three-stage electrodialysisElectrodialysis is feasible, which could be potentially implemented in other industries that involve the waste valorization of critical metals.

A series of operations have been developed to separate and recover individual critical metals from the end-of life lithium-ion batteries (LIB) based on their electrochemical and chemical properties. The black mass from waste LIBsWaste lithium-ion batteries contained Ni, Co, Li, and Mn, as well as contaminates such as Al, Fe and Cu. This paper highlights the leaching of metals and the recovery of Ni as part of a comprehensive recovery scheme. The electrochemical leach successfully dissolved over 97% of these metals into leachate and deposited over 98% of Cu onto cathode. The produced leachate was mildly acidic which could be used directly for Ni extractionNi extraction through ion-exchangeIon-exchange. Purity of the Ni-rich product was over 99%, and the precipitated NiSO4 powder possessed a higher Ni purity at 99.8%. Through these operations, we have successfully developed a feasible and flexible approach in recovery of critical materials and high purity metal salts from recycled LIBs.

The use of lithium secondary batteries for electric vehicles is increasing rapidly. In order to recycle batteries for electric vehicles, the discharge process is essential. The lithium-ion battery pack that is 227 kg and is series with 12 modules is composed of 20% cover materials, 14.4% plastics, and 59% battery cells. Each module which is series with 11 unit cells is composed of 18% frame body, 12% heat-reduce plate, and 70% battery cells. The waste LIBs pack was prepared by physical treatment, including hand disassembly, electric discharging, drying, and crushing. In the leaching process, 1mol/L H2SO4 and 10vol% H2O2 are added to the sulfuric acid reduction leaching and waste water reduction leaching process, and Al, Cu, Fe, etc. contained as impurities are controlled to be less than 10mg/L by precipitation as a pH adjustment. The solution with controlled impurities is applied to the solvent extraction system process with PC88A to selectively separate and extract manganeses, cobalt, and nickel. Finally, lithium left in the solution was concentrated to 18g/L and then, was precipitated as Li2CO3 with efficiency over 88%.

In the past, recyclingRecycling of refractory liningsRefractory Industry from the cement industryCement industry has not been possible due to contamination impregnating the linings during the cement production process. These contaminations lead to production issues and negative effects on the refractoriness when spent material is reused as raw material. RHIM has developed and patented a treatment method to reduce the contamination of spent refractories which technically enables their reuse. Linings based on this technology have a reduced CO2 footprint of up to 20%. However, a business model based on a circular economyCircular Economy requires additional developments to be implemented in the organization. As spent refractory linings are classified as waste, the legal framework of the supply chain must be adapted. A changed supply chain setup enables the sourcing and cross-border shipment of spent refractories. With the introduction of products containing recycled material to the market, the perception of these “waste” products must be positively changed.

Rio Tinto's Aluminium division operates smelters in Canada, primarily in the Saguenay–Lac-Saint-Jean region in Quebec, where its entire aluminium production line generates two specific calcium sulphateCalcium sulphate (CaSO4) by-products. The aqua-catalysed hydrated lime (CHAC) is the by-product of the sulphur scrubber at the coke calciner plant, and the neutralised synthetic anhydrite (SA) is derived from the industrial processes of the chemical transformation of calcium fluoride into aluminium fluoride, which is used in the manufacture of electrolysis bath for aluminium production. Since 2015, several research projects have been developed at the Rio Tinto-Arvida Research and Development Center, in collaboration with local universities, to evaluate the potential of these by-products as a liming agent for various agroecosystems and as a certified calcium-rich fertiliser for lowbush blueberries, our regional flagship. The aim of this paper is to present the research and development programme that has led to the agricultural recycling of these two by-products.

Complete utilization of every material mined seems to be a highly obvious strategy to save natural resources and avoid residues to be dumped. In fact, examples where this is practiced are very limited. Often residues out of metal production are not fully exploited and contain still considerable amounts of various valuable elements when being dumped. Using the full potential of mined material would significantly support the metal supply, while optimizing the CO2 balance, as much of the afford of winning a metal is already done, especially the mining. Not only the CO2 footprint, but also the avoidance of residues is an omnipresent topic nowadays. PyrometallurgicalPyrometallurgy treatment is unavoidably linked to slags. Regarding a zero-waste solution, these slags have high potential to be used as construction materials. Referring to this, zero-waste solutions for residues from primary zinc and lead production were tested, emphasizing the potential of this strategy.

This paper presents the results of characterization, thermal, and chemical treatments made over natural eggshellsEggshell (ES) and olive stonesOlive stones (OS) samples. The main goal was to perform an analysis to assess the potential of treated ES and OS to remediate heavy metals from polluted soils with mining tailings (PSMT). Sample powders of ES, OS, and PSMT were mechanically treated and characterized with chemical analysis, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric, and differential thermogravimetric techniques (TGA & DTG). ES was subjected to a calcinationCalcination test. OS samples were thermally treated and chemically modified with thiol. PSMT was characterized using specific gravity, average particle size, and environmental indicators. FT-IR analysis indicated the presence of CaCO3, Li2CO3, K2CO3, and KNO3 functional groups in ES and OS. The XRD analysis of ES samples showed the presence of one mineralogical phase (CaCO3). Diffraction patterns in the OS could not be identified due the amorphous condition of the sample. ES calcinationCalcination tests presented a mass loss near 47% (w/w). The process to obtain chemically modified pre-oxidized biochar from OS reported pyrolysis mass loss of 80.59%, pre-oxidized mass loss of 35.43%, and an addition of 0.14 g during the chemical treatment. Equilibrium diagrams showed that Cd+2 and Hg+2 are most likely in the PSMT soil solution (aqueous phase), whose cations could be removed via cation exchange of the calcinated ES. The mercaptoethanol content in the chemically modified pre-oxidized biochar could be effective in removing the Hg content in PSMT.

Global warming mitigation strategies include reducing CO2 emissions and encouraging the use of battery-powered electrical vehicles. Nickel in olivineOlivine which is an important mineral of many nickel sulfide mines and suitable for permanent CO2 sequestrationCO2 sequestration is regarded as non-recoverable and discarded in mine tailingsMine tailings as wastes. Enhancing nickel sulfide production from hitherto non-recoverable resources could help increase battery supply. This work shows that a copper nickel sulfide flotation mine tailingMine tailings in Minnesota could be used for directly accelerated mineral carbonationMineral carbonation and concurrent nickel sulfidizationNickel sulfidization. In addition to converting magnesium and iron silicates to mineral carbonates for permanent CO2 storage, nickel in olivine is concurrently converted to nickel sulfide for potential recovery. The mineral carbonationMineral carbonation of olivineOlivine is the dominant chemical reaction process and provides the precondition for nickel sulfidizationNickel sulfidization. A pre-concentration step of olivine from tailings is recommended to enrich olivineOlivine and nickel contents for potential application.

Benzoximic acid (BHABenzohydroxamic acid) is a commonly used collector in mineral processing industry. The accumulation of BHA in water will cause serious damage to environment. Therefore, how to efficiently treat the residual BHABenzohydroxamic acid in mineral processing wastewater is an important issue in the mineral processing industry. In this study, Fe(III) was used as chelating agent to separate BHABenzohydroxamic acid from wastewater by precipitation flotation. The optimum flotation conditions of BHABenzohydroxamic acid and Fe(III) were obtained by optimizing the chelation and flotation processes. The results showed that the chelating efficiency was the highest when the chelating pH was 7 and Fe(III) was 40 mg/L. When the addition amount of surfactant CTAB is 4 mg/L and the gas flow rate is 40 mL/min, the flotation removal rate of BHABenzohydroxamic acid reaches 90%, and the COD removal rate of the solution is 73%. The treated solution meets the first-class standard of industrial waste water discharge.

MolybdenumMolybdenum (Mo) is an irreplaceable alloying element of steel, resulting in the vigorous development of Mo metallurgy industry. However, abundant Mo-bearing wastewaters with low concentrations are concomitantly generated, which is difficult to recycle and gives rise to the waste of resources. In this work, recoveryRecovery of Mo from metallurgical wastewaterMetallurgical wastewater by Fe(III) chelation and precipitation flotationPrecipitation flotation process was investigated. The effects of pH value, Fe(III), HA dosage, and reaction time on the Mo recoveryRecovery efficiency from wastewater were systematically studied. The results showed that the molybdate in the solution can be coagulated by Fe(III) to form precipitation. HA can effectively increase the sizes of precipitation particles and improve flotation separation of Mo. After optimization, over 99.6% Mo was removed under the optimal coagulation and flotation condition. This technology can realize the effective recoveryRecovery of molybdate from wastewater.

There is uncertainty in the supply of rare earthRare earths resources. Technical developments on the resource saving of rare earths and the alternate materials are important challenges, and the development of recyclingRecycling technologies is also important for securing stable supply of rare earthRare earths resources. The waste of neodymium magnet that is the industrially-important product containing rare earth metals is currently recycled by a hydrometallurgical method. However, the hydrometallurgical method generates a large volume of waste solution and consumes a large amount of energy. In order to develop an environmentally-sound recyclingRecycling process, various studies on pyrometallurgical methodsPyrometallurgical methods have been conducted. One of the authors developed the molten metal extraction method and the flux remelting method. The pyrometallurgical methodsPyrometallurgical methods are anticipated as the recyclingRecycling processes with small waste generation and low energy consumption. Research and development on environmentally-sound recyclingRecycling technologies for rare earthsRare earths has to be advanced from environmental aspects as well as economic aspects.

Rare earth elementsRare earth elements (REEs) are critical metals for modern and emerging green technologies. Their increasing demand and limited supply have sparked the research on their recovery from secondary resources. The current study is focused on developing a hydrometallurgical process for the extraction of critical REEs from a waste byproduct, called phosphogypsumPhosphogypsum, and on elucidating the mechanism of the extraction process. Three types of mineral acids are used for the leachingLeaching, and a systematic study is utilized to assess the effect of operating parameters and to determine the optimum operating conditions. Thermodynamic modeling and solubility investigation shows the strong correlation between phosphogypsum solubility and leaching efficiency and the leaching process mechanism. Characterization results indicate that REEs can exist as isomorphous substitutions and/or separate phases inside phosphogypsumPhosphogypsum crystal. Based on these results, the destruction of phosphogypsum lattice is required to achieve improved extraction.

Recycling of wasteSupercritical fluid extraction electrical and electronic equipment (WEEE) has been receiving significant attention around the world. Here, we develop an environmentally sustainable process that uses supercritical carbon dioxide as the solvent along with a small volume of tributyl-phosphate (TBP) nitric acid adduct as the chelating agent to recover rare earth elementsRare earth elements (REEs) from fluorescent lamp waste. We show that mechanical activation using oscillation millingOscillation milling increases extraction efficiency. We elucidate the process mechanism by characterizing the solids before and after the process using transmission electron microscopyTransmission Electron Microscopy (TEM) and X-ray photoelectron spectroscopyX-ray Photoelectron Spectroscopy (XPS). We show that Al3+ and Ca2+ cations from the Al2O3 and Ca5(PO4)3OH (hydroxyapatite) present in the fluorescent lamp waste result in competing reactions with REEs with TBP-HNO3 adduct; thus, REERare earth elements extractions from real fluorescent lamp waste are less than what has been reported from synthetic feeds. Management of fluorescent lamp waste leads to sustainability of biosphere and circular economy.

Korea Institute of Geoscience and Mineral Resources (KIGAM), which is a unique government-funded Geoscience research organization in Korea, has researched and devised many technologies on mineral processing and extractive metallurgy for more than 70 years. In addition, several recycling processes have much studied from lab scale to pilot plant scale for the last two decades, and many technologies for the recycling of secondary resources, such as lithium batteries, neodymium magnet, catalyst, and so on, have been developed based on pyrometallurgy, hydrometallurgy, and electrometallurgy. Especially, some of them were already transferred to industry and commercialized in Korea. In the presentation, details of the recycling technologies at KIGAM will be introduced and discussed.

Phosphorous is an essential element for agriculture and industry and is a non-renewable resource. Especially yellow phosphorusYellow phosphorus is a critical material for advanced industrial technology, but phosphorus resources were not produced in Japan, and all depend on imports. It has been suggested, however, that the remaining accessible reserves of phosphate ore will be depleted within 50 years. Therefore, alternative resources for phosphate ore must be found. In this research, we have developed a process that enables the production of high-purity yellow phosphorusYellow phosphorus from domestic unused phosphorus resources such as steelmaking slags. The process consists of two parts: (1) the production of crude phosphoric acidPhosphoric acid from wastes such as steelmaking slag; (2) producing high-purity yellow phosphorusYellow phosphorus by low-temperature carbothermic reductionCarbothermic reduction of phosphoric acidPhosphoric acid (H3PO4). The details of the carbothermic reductionCarbothermic reduction of phosphoric acidPhosphoric acid are presented in this paper. Yellow phosphorusYellow phosphorus is commercially produced by carbothermic reductionCarbothermic reduction of phosphate ore in an electric arc furnace at more than 1673 K. In the newly developed system, gaseous P4O10 evaporated from H3PO4 is successfully reduced to yellow phosphorusYellow phosphorus using a carbon-packed bed at less than 1273 K. To meet the depletion of phosphate ore, the proposed process in this study to produce yellow phosphorusYellow phosphorus by carbothermic reductionCarbothermic reduction of H3PO4 that are extracted from dephosphorization slagsDephosphorization slags will be one of the practical and economical solutions.

Steel mill dust recycling today is an important business. However, most processes in operation hardly fulfil future requirements from the environmental point of view. In general, these treatment facilities show a certain CO2-footprint due to carbothermal reductionReduction and produce high amounts of residues which often have to be landfilled. The paper discusses possibilities to optimize state of the art processes regarding the realization of a zero wasteZero waste strategy and the minimization of the CO2-footprint. Furthermore, new developments are evaluated in respect of energy consumptions and environmental awareness. As an example, the “2-step-Dust-Recycling” process, an own development of the University of Leoben in Austria, is analyzed regarding its potential to meet requirements of present and future environmental legislation. Finally, the way how different options of steel dust treatment influence the overall zinc cycle, especially the role of zinc oxide from such sources as substitute for primary concentrates, is described.

Self-reductionSelf-reduction is a pyrometallurgical treating process that aims to valuable metal recovery from mining-metallurgical industry wastes, mainly from steelmaking industries. Electric Arc Furnace DustsElectric Arc Furnace Dusts (EAFD) (EAFD) are still the most attractive materials to be tested in using this technique, due to their high magnetite and franklinite/zinc ferrite contents. This research will address the reuse of these co-products in steel plants, providing added value to this material that until now is constituted as an environmentalEnvironment effects liability of considerable economic importance in steelmaking industries. Chemical and microstructural analysis has determined high contents of iron and zinc from magnetite and franklinite/zinc ferrite. Iron was present in the non-stoichiometric form of “hapkeite” (Fe1.34Si0.06) in both EAFD 1 and EAFD 2. A rare appearance of Moissanite CSi –2H was also found in EAFD 1. Thermogravimetric evaluations allowed elimination of almost 15% of volatile matter at 1000 °C in EAFD 1. EAFDs were partially reduced and showed a high porosity, which would make it possible for the recovery of its main metal content by carbothermic self-reductionSelf-reduction. Proximate analysis and carbon dioxide reactivity of two reductants were tested for evaluating the behavior of selected reductants in carbothermic self-reduction of EAFDs using a procedure given by the Steelmaking and Ironmaking Group of DEQM PUC/RJ. This mixture included 85% (EAFD + coal), 6% CPV ARI, and 9% water. Operational Diagram of Phase Predominance (ODPP) from the Zn–Fe–C–O system was used to calculate the required carbon and to guarantee the occurrence of the global chemical reactions of carbothermic reductionCarbothermic reduction either in franklinite/zinc ferrite as in magnetite by 100% CO and temperatures between 1000 and 1100 °C. In these conditions, self-reducing briquettes of EADF 2 lost more weight so reacted faster than EAFD 1. Finally, reactions rates of carbothermic self-reducing briquettes EAFDs were very fast during the first 5 min and retarded from 5 to 40 min.

The aim of the study is recovery of WC–Co cutting tool scraps through hydrometallurgicalHydrometallurgy methods. Scraps contain 83.67 wt.% W, 5.56 wt.% C, and 8.76 wt.% Co. The study consists of two progressive stages. The first stage is based on selective leaching of cobalt and separation from tungsten carbide. The second stage is the precipitation of cobalt from leach solution. Before experiments, scraps were grinded and sieved to lower than 250 μm particle size. In the first stage, WC–Co powders were leached in HNO3 solution. In order to achieve maximum dissolution of cobalt, acid concentration, temperature, stirring rate, and raw material particle size parameters were investigated. In the second stage of the study, dissolved cobalt ions from leach solutions were precipitated as Co(OH)2 compound by using NaOH solution. Solution pH and temperature parameters were examined to reach maximum cobalt recovery from the solution. According to results, the optimum leaching conditions were found to be 2M HNO3, 25 °C, 800 rpm, 2 h, and 1/10 solid/liquid ratio. Cobalt dissolution efficiency was detected as 94.87% under these conditions. Besides, dissolved cobalt in the leach solution was precipitated with an efficiency of more than 99.99% in the form of cobalt hydroxide by the addition of NaOH reagent at pH = 11 and 50 °C.

Transforming Foundation IndustriesFoundation industries Research and Innovation hub (TransFIRe) was developed in response to the UK Government Industrial Strategy Challenge Fund call to transform the Foundation Industries: Chemicals, Cement, Ceramics, Glass, Metals, and Paper. These industries produce 75% of all materials in the UK economy and are vital for the UK’s manufacturing and construction industries. Together, the Foundation Industries are worth £52 Bn to the UK economy and produce 28 Mt of materials per year, accounting for about 10% of the UK’s total CO2 emissions. TransFIRe is a consortium of 20 investigators from 12 institutions, more than 50 companies, and 14 NGO, and government organisations related to the sectors, with expertise across the FIs as well as material flows and energy mapping, life cycle sustainability, circular economyCircular economy, industrial symbiosisIndustrial symbiosis, computer science, AI and digital manufacturing, management, social science, and technology transfer. This paper will introduce the Foundation IndustriesFoundation industries, present the three work streams through which transformative change will be enabled, and initial plans for including a diversity of stakeholders.

With the development of the economy and the increasing annual output of copper, the treatment of copper slagCopper slag has become a more and more critical issue. Copper slag contains valuable metals such as iron, copper, gold, silver, lead, and zinc, which have extremely high recycling value. Physical, hydrometallurgical and pyrometallurgical methods for valuable metals recovery from copper slag are particularly reviewed in this paper. Besides, this paper then introduces a novel technique proposed by Northeastern University of China which can achieve high-value and slag-free treatment of molten copper slag. It is much preferred over the current methods. This method significantly increases the added value of the product and greatly reduces energy consumption. This paper reviews the comprehensive utilizationUtilization of copper slag and provides some recommendations for the large-scale and green utilizationUtilization of copper slagCopper slag in the future.

Material production drives an increasingly large fraction of CO2-equivalent emissions. Material efficiencyMaterial efficiency strategies such as recycling serve to reduce these emissions. However, prior analyses of such strategies do not include economically induced rebound effects, overestimating the associated environmental benefits. We present a dynamic supply chain simulation model for copper through 2040 incorporating inventory-driven price evolutionInventory-driven price formation, dynamic material flow analysis, and life cycle assessmentLife cycle assessment alongside mine-level economic evaluation of opening, closing, and capacity utilization decisions. We show that increases in recycling suppress raw material prices, driving increases in demand that limit primary production reduction and offset ~45% of the potential environmental benefits. Sufficiently small recycling increases and policy reversals were found capable of increasing mining and CO2-equivalent emissions. This model was expanded to accommodate regional variations and assess the impacts of China’s solid waste import ban and the COVID-19 pandemic, demonstrating the need for further investment in secondary markets.

Refractory high entropy alloysRefractory High Entropy Alloys (RHEAs) are considered candidate materials for high-temperature applications beyond nickel superalloys. In addition to good mechanical behavior, sustainabilitySustainability-related materials selectionMaterials Selection and design should be considered at an early stage of development, which will allow the application of RHEAsRefractory High Entropy Alloys to expand. In this work, we present an alloy design framework for RHEAs from three different perspectives. We evaluate resource availability based on geographic concentration for refractory elements and generate a supply risk index for each element. We then evaluate material prices and price volatility for each element. We also estimated an aggregate price of select alloys and compared them to their yield strength at room and high temperatures. A proper balance of improved performance and economics is considered. Finally, we evaluated environmental, physical, and human health hazards for refractory elements and used the Green Screen® for Safer Chemicals methodology to assign benchmark scores to each element.

Extending the useful life of a product through repair can significantly reduce the environmental impact associated with its production, and it can be less resource intensive than other environmentally virtuous practices like recycling. Wire and arc additive manufacturingAdditive manufacturing (WAAM) appears to be a promising approach in this context, being characterized by high-resource efficiency, flexibility to perform repairs, and having recently gained industrial maturity. In this work, a methodology to assess the life cycle environmental sustainabilitySustainability of repaired products through WAAM will be presented with a real-world, industrial case study.

The REMADE Institute invests in research and development to develop technology solutions to enable the increased remanufacturingRemanufacturing and recyclingRecycling of metalsMetals, polymersPolymers, fibersFibers, and e-wasteE-waste. Increasing the recycling and remanufacturing of these materials can significantly contribute to an increase in energy efficiency, an increase in materials use efficiency, and a reduction of GHG emissions in the domestic manufacturing sector. The current R&DR&D portfolio of REMADE is structured across five activities including systems analysis and integration, manufacturing materials optimization, design for Re-X, remanufacturingRemanufacturing and end-of-life reuse, and recovery and recycling. This paper outlines the mission of the Institute, provides an overview of the structure and approach in developing the R&DR&D portfolio, and describes a few of the projects and their beneficial energy, materials, and environmental impacts from our broad R&DR&D portfolio.

AluminumAluminum is widely used in buildings, transportation, and home appliances. However, primary aluminumAluminum production is a resource-, energy-, and emission-intensive industrial process. At present, ChinaChina is the world's largest producer of aluminumAluminum. Under China’s new national development pattern of the “internal–external dual cycle”, China’s aluminumAluminum industry (AID) future development may also need to be adjusted. This study combines material flow analysisMaterial flow analysis, life cycle assessmentLife cycle assessment and scenario analysisScenario analysis to investigate the potential of resource conservation, energy saving, and emission reduction for China'sChina AID till 2030 under the transition of import and export trade. The results show that nearly 40% of China’s annual aluminumAluminum production entered the inventory in use in other parts of the world through trade between 2010 and 2017. In the business as usual (BAU) scenario, the bauxite consumption of China's AID will increase from 170 Tg in 2017 to 291 Tg in 2030, with an annual growth rate of 4.2%. Compared with the BAU scenario, the demand for bauxite in the two scenarios of reducing exports of aluminumAluminum products will be reduced by 27% (Scenarios A) and 47% (Scenarios B) in 2030, respectively. In addition, there are obvious benefits in terms of water saving, energy saving, and emission reduction under Scenarios A and Scenarios B. Therefore, promoting the transformation of imports and exports can effectively decrease the external dependence on bauxite of China'sChina AID and is also an important means to achieve carbon peaking by 2030.

BatteryBattery storage technologies such as redox flow batteries (RFBs) and lithium-ion batteries (LIBs) are appealing candidates for large-scale energy storageEnergy storage requirements to support the integration of renewableRenewable energy into electric grids. To ensure that their environmental benefits outweigh the environmental costs of producing battery storage systems, it is vital to assess the potential health impacts of battery materials and waste emissions during production. Here, we present a case study based on life cycle impact assessmentLife Cycle Impact Assessment (LCIA) to characterize the toxicity hazard associated with the production of six types of battery storage technologies including three RFBs [vanadium redox flow battery (VRFB), zinc-bromine flow battery (ZBFB), and the all-iron flow battery (IFB)], and three LIBs [lithium iron phosphate (LFP), lithium nickel cobalt manganese hydroxide (NCM), and lithium manganese oxide (LMO)]. USETox® v2.0 (USETox®) was used for LCIA and we found higher impacts found higher impacts on human health outcomes for the production of LIBs than for RFBs, noting that uncertainties associated with the characterization factors demand caution in interpreting the results. Overall, the study provides (1) a comprehensive evaluation of life cycle impacts for materials, components, and systems associated with the production of burgeoning six batteryBattery energy storageEnergy storage technologies and (2) an important foundation for the identification of battery technologies with lower potential negative impacts associated with integrating energy storageEnergy storage in strategies for upscaling renewableRenewable energy sources.

Bacteria of the Legionella family are known to grow in water-cooling systems, where conditions are favourable. Because these bacteria can cause Legionnaires’ disease (Legionellosis), the owners of such systems are bound by legal obligations. Currently, the only accepted method for the legal requirements for quantifying Legionella in all type of water-cooling systemsCooling systems—growth on a culture medium—can take up to 14 days to obtain results, which does not allow proactiveness. The technology tested in this project, the BioAlert Lp15BioAlert Lp15TM™ by BioAlert Solutions, is a fully automated, on-site equipment that samples, quantifies, and sends a Legionella result within four hours. The technology showcase project described herein has demonstrated the applicability of the equipment in heavy industry environments as it was possible to establish a control and action chart based on the daily results obtained with the BioAlert Lp15BioAlert Lp15TM™. This instrument provides numerous benefits, such as a lower risk of Legionella exposure, better understanding of the Legionella metabolism and its influencing factors, improved operational practices and, finally, reduced impacts on production.

The cumulative global solar panel waste stream is projected to reach between 60 and 78 million tonnes by 2050. Steps towards developing, demonstrating, and implementing processes that recover glass, metals, and semiconductor materials from end-of-life solar panels have already been taken. However, these processes result in the downcycling of most secondary solar materials. Critically, the costs and benefits of capturing these secondary materials for use in new solar panels are unknown. To evaluate the environmental benefit associated with solar material recycling and reuse in next generation panels, prior inventories must be updated and prepared for integration with recycling processes to examine the benefit of closing the material loop between solar panel end-of-life and new panel manufacturing. This current work describes steps taken to upgrade existing inventories that detail the manufacturing of cadmium-telluride (CdTe) panels from the Ecoinvent -v2.2 life cycle inventory database to Ecoinvent -v3. During this update, material inventories were modified to capture different realistic material supply chains within the constraints of Ecoinvent -v3. Materials discussed in detail in this work include primary flat glass, aluminum, steel, copper, and CdTe. This work demonstrated that environmental indicators such as embodied carbon, acidification, and terrestrial eutrophication associated with solar panel production can be reduced by 25% to over 40% through improved primary material sourcing.

To ensure that the production cost of batteryBattery energy storageEnergy storage systems for the electric grid does not compromise the environmental benefits gained from the substitution of traditional fossil fuels, it is important to evaluate and manage the cost feasibility of the feedstock materials used in battery production. In this study, we present a techno-economic analysisTechno-economic analysis to evaluate the cost of materials in three emerging redox flow battery products: vanadium pentoxide redox flow batteries (VRFB), zinc-bromine flow batteries (ZBFB), and all-iron flow batteries (IFB), with a focus on primary materials used in functional components. Furthermore, we performed sensitivity analysis for selected materials to explore the uncertainty due to dynamic variation in market prices. The normalized results indicate that the major cost contributors for each batteryBattery type vary significantly over time, and the historical variations in material pricesMaterial prices could largely affect the battery system production cost. Thus, material costs should be considered as a key attribute in material selection and product design for installing flow batteryBattery technologies in the electric grid.

Embracing the circular economy, this paper will discuss recent work that scales reactor technology to system models with relevant digital twins. The aspects that are discussed are best explained by the figure below.

For a significant shift in alloy designAlloy design to happen, the aluminiumAluminium industry needs to explore a broader range of compositional and processing dimensions. This work provides the background to guide the design of new alloys, especially where opportunities are present to improve recyclability. To achieve this, a blending model with an integrated material flow analysis will be optimised over compositional space to inform alloy compositions that enable higher quantities of scrap use. Blending models inform the scrap usage of a candidate alloy when it is set in a predetermined market landscape. Due to their computational cost, machine learning optimisation methods such as Bayesian optimisationBayesian optimisation will be employed to focus the design process. The optimisation will be subject to constraints that are based on compositions, phase combinations, and relevant properties to ensure that the alloys not only maximise the amount of scrap use but also meet technical requirements. This manuscript describes the background content that will inform this work.

This paper attemptsOnline sensing to address key challenges to automate unit operations (e.g., disassembling and sorting battery components at the cell level) of the lithium-ion batteryLithium-ion battery direct recyclingBattery recycling process. In our previous publications, we introduced the design and prototype of an automated disassembly system that can separate cell cases, metal tab, cathode, anode, and separators of a LIB pouch cell with minimum human intervention. In this paper, we take one step further to integrate industrial vision cameras and sensors into the prototyped system which allows real-time process defect detection and corrective action. Specifically, this paper focuses on online sensorOnline sensing integration in the electrode sorting step for separating cathode and anode electrode sheets. The electrode sorting and separation method developed here simplifies the subsequent materials extraction and purification operations of the LIB direct recyclingBattery recycling.

Steel is one of the most important engineering and construction materials and plays a critical role in the overall economic development. However, iron and steel industry is one of the most energy-intensive industries which accounts for >20% of global industrial energy use and about a quarter of industrial CO2 emissions in the world. Energy efficiency improvements are one driver for production optimizations, but efficiency improvements in steel production can be reached in several ways like equipment availability improvements as well as yield increases or optimized production schedules.

This paper deals with refractory lifetime prediction by using artificial intelligenceArtificial intelligence (AI). Through the effective use of process parameters, obtained from various operational processes within the Industrial (Cement/Lime, Non-Ferrous Metals, Process Industries, Foundry) and Steel sector, an AI model is generated. With the assistance of modern surveying technology, a correlation can be identified between process parameters and refractory wearRefractory wear. Using this method, suitable prediction of the refractory lifetime, as well as the wear mechanism, is possible. In addition, maintenance cycles can be adjusted, and the optimal maintenance intensity of the operated furnaces can be ensured. With our intelligent Automated Process OptimizationProcess optimization (APO)Automated Process Optimization (APO) solution, the prediction of refractory lifetime and wear mechanism can be done in real time. Thus, we can provide value-added service to our customers.

Computer simulationComputer simulation, visualization,Visualization and machine learningMachine learning are increasingly playing key roles in the digitalization of advanced manufacturing processes. These technologies can be used to create cutting-edge physics-based and data-driven tools for real-time decision making to address critical issues related to energy efficiency, carbon footprint, and other pollutant emissions, productivity, quality, operation efficiency, maintenance, and more. They can also provide fundamental understanding and practical guidance for process design, troubleshooting, and optimization, new process development and scale up, as well as workforce development. The Center for Innovation through VisualizationVisualization and Simulation (CIVS) at Purdue University Northwest, established in 2009, has used these technologies to develop and implement digitalization for Advanced Manufacturing in partnerships with steel and other industries.

Pyrometallurgical recovery of nonferrous metals involves a combination of thermally intensive transformations during exothermic gas-phase reactions, endothermic decomposition of solid charge, and meltingMelting of simpler solids. In the recovery of secondary leadLead, simultaneous thermal effects in a reverberatory-style furnace cause a melt pool to accumulate at the bottom, with lighter solids (slag) floating above and gaseous products from decomposition of the charge diffusing through the gas–slag interface. Species from oxy-fuel combustionOxy-fuel combustion of natural gas, species profiles from smeltingSmelting reactions, and the formation of a melt pool consisting primarily of leadLead are simulated via a time-averaged formulation. Predictions of outflow are compared with preset inflow profiles to ensure conservation of mass. Thermal profiles for solid, liquid, and gas phases are presented by species. A novel method is implemented to model the latent heat of fusion using a heterogeneous chemical reaction. The simulation is conducted in Simcenter STAR-CCM+ v. 16.02.009-R8.

High-pressure die castingDie casting is a complex manufacturing process that requires a highly developed work force. A virtual die castingDie casting machine has been developed for operators to provide a better understanding of how the machine works and how to deal with a variety of practical situations and issues that arise on the shop floor. Computational fluid dynamics (CFD) simulations have also been developed and integrated into the simulatorSimulator to help die casters understand how parameters such as shot speed can affect the resulting quality of castings being produced. A virtual melter furnace is also being developed to learn and practice maintenance and safety procedures. The simulatorSimulator was developed for virtual realityVirtual reality (VR) headsets and controllers, but is also usable on standard PC with mouse and keyboard. Development methodology and overview of simulatorSimulator functionality will be discussed.

As a natural product with limited resources, sand is of existential importance for various industries. Foundry technology in particular requires considerable quantities worldwide for sand moulds and cores. Depending on the processProcess technology, the sand is recycled and thus reused. However, especially in the case of inorganically bound moulding sand, it is still frequently not recycled. Existing regeneration methods include mechanical, pneumatic, or combined processes. These have been developed, but have reached their analytical optimisation limits, as the processes are not transparent and make in situ analyses of moulding materialsMoulding material impossible. Within the scope of this research work, a methodology for the computer-aided processing of sound and image data with the help of convolutional neural networksConvolutional Neural Network (CNN) (CNNs) was developed, which is to evaluate the non-measurable changes of the moulding materialMoulding material in the running process in real time via process acoustics. The aim is to optimise process control in terms of time, cost, and energy efficiency.

Top submerged lanceTop Submerged Lance (TSL) (TSL) smelters are widely used in non-ferrous metallurgy to extract various primary and secondary materials. The technology has found wide application with regard to copper, lead and zinc, nickel, tin, while applications concerning iron and municipal solid waste treatment have been reported. As of 2019, there are about 66 known operating TSL plants globally. By controlling the air/fuel ratio (i.e. by lambda value), the TSL can be operated under oxidizing/reducing/inert conditions. The bubble dynamicsBubble dynamics play a crucial role in determining the reaction kinetics, splashing, turbulence, sloshing as well as the refractory and lance wear. This paper shows the efforts to determine the bubble dynamicsBubble dynamics in a cold TSLTop Submerged Lance (TSL) model using acoustic measurementsAcoustic measurement and high-speed photographyHigh-speed photography. The results show a correlation between bubble dynamics with respect to varying lance submersion depths, bath properties (varying viscosities and densities, i.e. glycerol/water mixtures), and lance flow rates (i.e. airflow).

Flue gas recirculationFlue gas recirculation (FGR) for the siliconSilicon process may facilitate increasing the CO2 concentration in the off-gas, which will be beneficial for potential future carbon capture. Lower oxygen concentration in the combustion gas will also reduce NOX emissions. An existing 400 kVA submerged arc furnace (SAF) pilot setup was modified to be able to recirculate flue gas and equipped with gas analysis to monitor both the flue gas and the mixed combustion gas entering the furnace. Over a running period of 80 h, including 32 h of startup, twelve different combinations of FGR ratios and flow rates were tested using typical industrial raw materials. Increased CO2 flue gas concentrations were successfully demonstrated with concentrations over 20 vol. % CO2. Emissions of NOX were shown to be reduced when isolating stable comparable periods within each tapping cycle.

Mineral carbonationMineral carbonation of industrial byproducts is a promising carbon capture and storage technique to abate global warming. Steelmaking slagSteelmaking slag is the main byproduct of the steelmaking industry, and it is a potential source of alkaline oxides which can be transformed into carbonates. The carbonation of the steelmaking slag has proven to be a great countermeasure to sequester significant amounts of CO2 emitted from the steelmaking process at the point sources while offering the environmental benefits of waste reduction. In this study, a supercritical carbonationSupercritical carbonation process is developed to sequester CO2 using steelmaking slagSteelmaking slag. Compared with conventional aqueous carbonation, this process has several advantages including higher reactivity, less waste generation, and better economic feasibility. A response surface methodologyResponse surface methodology is utilized to assess the effect of operating parameters on carbonation efficiency and to optimize the process. Under the optimum conditions, the maximum CO2 uptake of 213 gCO2/kgSlag is achieved. We believe that the findings of this study would help enable efficient CO2 mitigation utilizing an efficient and environmentally sustainable process and thereby contribute to carbon neutrality and waste reduction.

Production of manganese alloys is an energy intensive process associated with high carbon consumption. In the wake of the Paris agreement, manganese alloys producers have implemented new strategies to minimize the environmental footprint of smelting and refining activities. At Eramet Norway, process decarbonization is well underway with the goal to reduce CO2 emissions by 43% within 2030. Initiatives cover the full manganese alloys process range, starting from the assessment of carbon neutral reagents and pre-processing of the manganese ore to downstream reuse of furnace offgas as energy vector. In collaboration with a rich grid of academic and industrial partners, Eramet Norway is especially investigating solutions for carbon capture and storage from manganese alloys furnace gases. Technical challenges are associated with the presence of deleterious components in the flue gas as well as process discontinuities, while economic feasibility is relying on maximizing upscale efficiencies, developing downstream networks, and securing governmental support.

Recently, huge emissions of carbon dioxide have emerged as a major problem in different fields of engineering. Mixed matrix membranesMembrane are materials with huge potential for application in the field of carbon dioxide removal from the flue gases. Preliminary experiments have shown that dense compositeComposites membrane with polyethyleneoxide (PEO) as a matrix and zeolite powder as a dispersed phase with appropriate additive that serves as a homogenizer can be used. This type of membranesMembrane has shown good permeability of carbon dioxide and relatively low permeability for other gases (hydrogen, oxygen, nitrogen). The aim of this work is to test potential degradation of permeation properties and mechanical consistency of the membrane under repeated cycles of heating and cooling in presence of moisture. The experiments were performed at five different temperatures below melting or degradation point of polymersPolymers with three different partial pressures of water in combination with various gases. It was found that permeability of each gas will reach constant value after certain number of measurements.

Concrete, a mixture composed of a cementation agent, mineral aggregates, and water has the potential to serve as a gigaton-scale sink for carbon dioxide (CO2). This could make concrete the world’s largest CO2 utilizationCO2 utilization opportunity. CarbonBuilt’s Reversa™ process, developed at UCLA’s Institute for Carbon Management exploits simple acid-base chemistry to mineralize CO2-dilute flue gas emissions into mineral carbonate-based cementation agents at ambient pressure, at flue gas temperatures, and without a need for carbon capture. The approach leverages innovations in the use of portlandite (Ca(OH)2: calcium hydroxide, or slaked lime) which carbonates readily, and produces limestone (CaCO3: calcium carbonate)—a potent cementation agent—upon its carbonation. Within the scope of a project sponsored by the US Department of Energy’s Office of Fossil Energy, the Reversa technology was upscaled and demonstrated using a modularized pilot-plant at the Integrated Test Center (Gillette, WY) and National Carbon Capture Center (Wilsonville, AL) using coal- (~12 vol. % CO2) and natural gas (~4 vol. % CO2) flue gas streams. The field demonstration led to the production of over 15,000 concrete masonry units (CMUs, also known as concrete blocks) and achieved: (1) a CO2 utilizationCO2 utilization efficiency in excess of 75%, and (2) greater than 250 kg of CO2 utilizationCO2 utilization per 13 tonnes of concrete (i.e., one production run). Importantly, based on rigorous third-party validation, the CMUs produced were confirmed to be compliant with all relevant industry specifications (ASTM C90). The success of this demonstration suggests that the pioneering Reversa technology is ready for commercialization.

Over the past decade the European Union has set the ambition to become a carbon neutral and fully circular economyCircular economy. To achieve this, it will be necessary to develop new technologies and processes that address both issues simultaneously. In this paper the HIsarnaHIsarna ironmakingIronmaking technology is used as an example where the reduction of CO2 emissions, the use of secondary raw materials as well as the valorisation of by-product streams is considered in the early stages of the process development. In the light of climate change, sustainabilitySustainability, resource efficiency and circularity these aspects should be part of the considerations for any new process being developed, even if their economic viability still needs to be established.

A new prospective in the Egyptian steelmaking industryEgyptian steelmaking industry using pure hydrogen to reduce waste iron ores in a two-stage fluidized bed reactor through direct reduction processDirect reduction process is presented, modeled, and analyzed. The main advantage of applying this route to the steel industry is the enormous reduction in CO2 emissionsCO2 emissions compared to today's dominant routes that rely on the blast furnace—basic oxygen furnaceBlast furnace – basic oxygen furnace (BF/BOF). Moreover, the hydrogen direct reduction (H-DR) process could be directly applied for the reuse of the waste imported lump iron oresWaste imported lump iron ores that are been crashed during the transportation process to a small fines particles; making them unusable in blast furnace processes unless sintering process is applied. A complete study to verify the applicability of this idea in Egypt has been investigated and comparing it to current fluidized bed reactor using syngas as the reducing agent.

The production of ferrochromeFerrochrome via carbothermic reduction in submerged arc furnaces is an energy-intensive process relying on the usage of coal and coke as reducing agents. The pre-reductionPre-reduction of chromite in a rotary kiln is currently carried out to decrease the specific electric energy consumption in the smelting furnace. However, as fossil reductants are still needed for reduction, CO2 is emitted. The usage of bio-based carbon with a faster carbon cycle compared to fossil reductants could be an option to decrease the specific CO2 footprint of FerrochromeFerrochrome production. In this paper, the pre-reductionPre-reduction of chromite was investigated using various bio-based reducing agents and lignite coke as a fossil reference. Isothermal reduction trials were conducted at 1000, 1150, and 1300 °C and different holding times. While at lower temperatures the pre-reductionPre-reduction was insufficient, the bio-based reducing agents yield a degree of reaction between 61.0% and 65.4% at 1300 °C reaction times of 360 min. The highest degree of reaction is reached using coconut charcoal, followed by corn, olive, and bamboo charcoal. Coke results in the lowest degree of reaction with 51.9%. While the bio-based reducing agents performed similar after long reaction times, significant deviations were observed for shorter reaction times. X-ray diffraction was carried out to investigate the obtained product, which showed that the pre-reductionPre-reduction was mostly due to the formation of carbides, while the intensity of metals in the sample was rather low.

One of the focus areas for research conducted by the PyrometallurgyPyrometallurgy Division at Mintek in South Africa is decarbonisation of the metals industryMetals industry. In a country with a large pyrometallurgical industry, based primarily on carbonaceous primary reduction processes and electricity generated primarily by coal-fired power stations, the challenge can be viewed from a number of perspectives. The paper provides a summary of the projects currently underway, where the Technology Readiness Levels (TRL) ranges from TRL 1 to TRL8.

The increasing consumption of carbon-based products in recent decades and their impact on the environment and climate change is becoming more and more significant. To curb this problem, the use of pyrolysed biomassBiomass as a reducing agent substitute for carbon-based reduction processesReduction process can be part of the solution for a CO2-neutralCO2-neutral metallurgy. Previous research has shown that biochar can be a replacement for conventionally used carbon sources. However, the economic interest in this technology has gradually decreased, due to the falling prices for the CO2-certificates about eight years ago. In the meantime, the prices for the certificates have risen strongly again and the topic is coming back into focus. In this publication, the use of biomassBiomass was investigated in an experimental setup and the selection, properties, and possible applications are discussed. The results show that biomassBiomass can be an adequate product for CO2-neutralCO2-neutral process control.

PlasmaPlasma species such as monoatomic hydrogenHydrogen are much more reactive than diatomic hydrogen gas, H2(g). This means that plasma technology can be a way of introducing hydrogen as a reducing agent for producing metals and alloys, like manganeseManganese., where oxide reduction to the metallic state by hydrogen gas is not possible. While still an immature technology, it is nevertheless important to address questions regarding economicEconomy relevance. In this work, best estimates are used to describe a hypothetical plasma-based process and plant for manganese production. This description then makes the foundation for a techno-economic analysis comparing this hypothetical process with existing standards. It is found that at present, it seems plausible that hydrogen plasma technology can compete economicallyEconomy, and thus be a viable way to decarbonise manganeseManganese. production. The most sensitive parameters appear to be hydrogenHydrogen price, cost of CO2-emissions, and to what extent excess energy from the plasmaPlasma unit can be captured and used for pre-heating of the ore.

State-of-the-art solar-grade silicon productionSilicon production is energy intensive and has a negative impact on the environment. Due to the robust and rapid growth of the Si-based photovoltaic (PV) industry, it is necessary to develop a greener technology for silicon productionSilicon production. Solid oxide membrane (SOM) electrolysis is a proven versatile green technologyGreen technology that can be developed to economically produce many important metal or metal compounds from their oxides. This work will discuss application of SOM electrolysisSOM electrolysis to produce solar-grade silicon from silica in a single-step resulting in net-zero-carbon emission. The high-temperature SOM electrolysisSOM electrolysis cell employs stable molten oxide-fluoride bath with silicon wafer cathode and stabilized zirconia membrane-based novel anodes. The cell design and process parameters are selected to enable silicon deposition on the Si wafer cathode. However, initially an electrochemical oxidation reaction occurred between silicon and oxygen that involved the cathode/flux/gas interfaces. An approach to successfully prevent this side reaction has been demonstrated. Electrochemical characterization of the SOM process is presented, and post-experimental characterization demonstrates Si deposits in the form of silicon carbide due to the use of graphite crucible and graphite current collector.

In Korea, ~20% of waste glass bottles are buried in landfills every year. Many studies have been conducted to utilize this waste in foamed glass and cement production. However, more research is needed to find efficient methods to convert the waste to valuable materials, such as recycled fine aggregates. In this study, we designed an integrated crushing-grinding-separation process involving additional crushing equipment to handle large amounts of waste glass bottles and determined whether the products met recycled fine aggregate quality standards. Waste glass bottles were crushed to a size less than 10 mm using a pilot-scale shredder and roll, hammer, and vertical shaft impact (VSI) crushers. We found that the VSI crusher is the most suitable equipment, in terms of crushing performance and ease of operation, to convert the glass bottles to recycled fine aggregates. The crusher generated products exhibiting aspect ratios less than those of natural sand in most particle sizes. The proposed process is a promising way to convert glass wastes to recycled aggregates. We expect that incorporating optical-sorting-based techniques into the process will further increase the recycling rate of waste glass bottles, even from a mix of bottles with different colors.

The technology of LED lampsLED lamps has revolutionized the lighting market, stimulating its consumption. Consequently, a generation increasing of this type of waste is observed, LED lamps are composed of carcass, PCBs, strips and LEDs. The lamps have metals with economic potential for recycling. Al and Cu are the main metals in strips and can be recycled through hydrometallurgical techniques. Thus, this work aims to evaluate the possible recoveryCu recovery of Cu from tubular led lampsLED lamps strips. The first stage of the study is the strips characterizationCharacterization through chemical analysis by ICP-EOS, and SEM. The next stage is the leaching thermodynamic simulationThermodynamic simulation using FactSage 8.0 software. The strips characterization showed contents of 88% of Al and 8.5% of Cu. The thermodynamic simulationThermodynamic simulation shows possible selective leaching of Cu against Al, under the following conditions: HNO3, pH 3–3.8, Eh above 0.55, and 25 °C; and NH3, pH 7–10, Eh −0.15 to 0.6, and 25 °C.

With the increasing awareness of environmental protection, the disposal of solid waste such as red mudRed mud (RM) and silica fumeSilica fume (SF) has attracted widespread attention. In this study, a novel method by recycling RM and SF simultaneously was proposed for preparing Fe-Si alloyFe-Si alloy and extracting alumina. The process is mainly composed of vacuum carbothermal reductionVacuum carbothermal reduction and magnetic separation. The results show that Fe-Si alloy was successfully synthesized during the vacuum carbothermal reductionVacuum carbothermal reduction and it was effectively separated during the magnetic separation. Additionally, after the magnetic separation, the non-magnetic portion mainly contains alumina and it can be a potential raw material to produce alumina by the Bayer process. This process could recycle RM and SF simultaneously, and almost no waste residue was generated. Therefore, it provided a clean and sustainable route for synergistic recycling of RM and SF.

The review deals with geopolymersGeopolymer based on construction and demolition wasteConstruction and demolition waste (CDW). A review of the research of the last 5 years (2015–2020) is presented in three different study areas: Energy—Business, Management, and Accounting—Environmental Sciences. This article initially emphasizes the environmental impact from the point of view of opportunities for this type of recycled materials. In a second part, it focuses on the experimental design of geopolymersGeopolymer, concentrating on the used materials and manufacturing methods. Finally, the third part focused on the mechanical properties obtained by different authors, carried out via a systematic review for providing a detailed summary of the different parameters found in the literature.

At KIGAM, the pilot plants have been developed and demonstrated two processes for recyclingRecycling NdFeBNdFeB magnet waste magnets and manufacturing scraps. The former process uses thermal oxidation as a pretreatment before. The latter does caustic digestion and the thermal oxidation process. About 35% of the iron in feed was co-leached with REEs upon leaching of thermally oxidized products. Therefore, the separation process of REEs and non-REEs was carried out using the double-salt precipitation method to produce a high purity REEs solution applicable for solvent extraction. Instead, the leaching yield of iron upon leaching of caustic digestion and thermal oxidation products showed a value of 0.01%. Thus, the high purity REEs solution was obtained and directly applied to solvent extraction. Finally, REEs compounds of 99.9% or above could be obtained by solvent extraction using mixer settler and precipitation from raffinate and stripping solutions.

Substituting carbon with hydrogenHydrogen is one of the few ways metal production can potentially become free of CO2 emissions. Moreover, the metallurgical industry produces significant amounts of waste. The present work presents a circular concept that will be pursued in the HARARE project, based on increasing waste recovery by the use of hydrogen. The project will tackle two example cases: bauxite residueBauxite residue and copper smelter slags. The common theme is to use hydrogenHydrogen to selectively reduce iron and copper, making it possible to extract these metals. Through a series of pyro and hydrometallurgical steps, as well as mechanical separation, it is also possible to recover secondary valuables like alumina, molybdenum, cobalt, nickel, zinc, and scandium. The final remaining residues can be valorised as building materials for a truly zero-waste concept. In this paper, the different process streams for the two example cases are laid out, including the valorisation of secondary material streams.

LithiumLithium (Li) is the lightest energy critical element used in manufacturing of active cathode materialActive cathode material of lithium-ion batteries (LIBs). Thus, the consumption of lithium is constantly increasing in the LIBs. Meanwhile, LIBs become obsolete after reaching its end-of-life resulting in the generation of huge amount of spent LIBsSpent LIBs. Present study reports the roastingRoasting and leachingLeaching process for selective recovery of Li from active cathode materialActive cathode material. To optimize the process parameters viz. roasting temperature, time, and mass ratio studies were carried out varying the experimental conditions for the conversion of lithium oxide to lithium sulfate from the complex of lithium cobalt oxide. It was found that cathode material converted into lithiumLithium sulfate at 750 °C in two hours maintaining mass ratio of LiCoO2/Na2SO4: 1/0.5. Subsequently, 99.1% Li was leached from roasted product at 75 °C in de-ionized water within two hours. Further, Li can be precipitated as lithium carbonate using sodium carbonate.

The selective recovery of rare earth elementsRecovery of rare earth elements from Nd-Fe-B magnetsNd-Fe-B magnet through a novel selective chlorinationSelective chlorination process using zinc chloride was investigated. A Nd-Fe-B magnetNd-Fe-B magnet powder and zinc chloride mixture in an alumina crucible was positioned in a gas-tight quartz tube. This quartz tube was placed in an electric furnace preheated to 1000 K for 1.5 h for the reactions. After the experiments, a mixture of metallic iron and neodymium chloride was produced owing to the selective chlorination of rare earth elements in the magnet powder. In addition, the chlorination efficiencies of neodymium, dysprosium, and praseodymium were 96.5%, 57.2%, and 97.6%, respectively, under certain conditions. Therefore, it was demonstrated that the novel selective chlorinationSelective chlorination using zinc chloride developed in this study is feasible for the efficient recycling of Nd-Fe-B magnets.

Recycling of automobile catalytic converters was studied using the cyanidation at an elevated temperature and pressure that dissolving Pt-group metals (PGMs) followed by their liquid–liquid separation with ionic-liquid Cyphos IL101. PGMs were efficiently dissolved by autoclaving of the spent catalysts sample preconditioned in 2.0 M NaOH solution at 90 °C for 60 min duration. The cyanide used in the study was metabolically produced by Chromobacterium violaceum. Under the optimized autoclave leaching process at temperature 150 °C, pO2 200 psi, and time 120 min, approximately 90% PGMs could be dissolved. The residual cyanide can be subjected to the biodegradation within the bacterial life-cycle.

Separation and recovery of molybdenumMolybdenum and vanadiumVanadium from leaching solution of spent catalyst are of great significance for resource utilization of spent catalyst. In this work, selective separationSelective separation of molybdenumMolybdenum was comprehensively investigated by tributyl phosphate (TBP) with the emphasis on the hydrochloric acid concentration, TBP concentration, reaction time, and oil–water ratio. The results indicated that molybdenumMolybdenum was effectively extracted by 40% (v/v) TBP. More than 95.2% molybdenum was extracted, while the extraction percentage of vanadiumVanadium was negligible under the optimal conditions (hydrochloric acid concentration of 2 mol/L, reaction time of 10 min, and phase ratio (O/A) of 1/2). Furthermore, the molybdenumMolybdenum in loaded organic phase can be stripped using 0.1 mol/L sodium hydroxide, which achieves the selective separationSelective separation of molybdenum and vanadiumVanadium.

CO2 activationCO2 activation plays an important role in CO2 utilization. Thus, the catalystCatalysts consisting of Cu-Ni supported on graphene oxide (GO), ammonia modified graphene (NGO), and reduced graphene oxide (rGO) were synthesized. Their properties were analysed by BET, XPS, TEM, and TG-DSC. The specific surface area of supports followed the order of ammonia modified grapheneCommercial graphene (NGO) > graphene oxide (GO) > reduced graphene oxide (rGO). Cu0 existed in rGO and NGO supported catalysts. 29.5% of Cu2+ was reduced to Cu+ or Cu0 in rGO. In NGO, 30% of Cu2+ was reduced. Most of the Cu and Ni was dispersed uniformly on these two supports. In GO, some particles were sintered, which was composed of Cu and Ni with a size up to 100 nm. In rGO and NGO, the metal particle size was less than 50 nm. The CO2 activationCO2 activation energy was determined by TG-ESC experiment, and the calculation was done by Ozawa method. The results showed that CuNi-rGO and CuNi-NGO could activate CO2, and the activation energyActivation energy (E) was 78.26 and 91.30 kJ·mol−1, respectively. Compared with literature, these catalystsCatalysts could reduce the activation energyActivation energy (E) by 48%.

Coal fly ashCoal fly ash (CFA) (CFA), solid waste from the thermal power plant, is gaining attention as an alumina content substitute, but its production has long been considered to be problematic in environmental management. Many researchers have proposed and developed utilization technologies that can help to solve these problems by utilizing large amounts of the CFA. This review aims at pointing out aspects for CFA utilization; one aspect of the utilization technology that has had a great impact on the material society is how it affects the environment, and the other is the recovery of rich minerals. The current research status, progress, and future scope of research on CFA will be reviewed in this paper based on comprehensive research data. More research is required to provide a better understanding of the reaction mechanism and economic advantagesEconomic advantages of CFA. This review paper provides existing opportunities to motivate researchers to be involved in this study.