Primary Metal Production Research Articles

PERHITUNGAN EMISI GAS RUMAH KACA DALAM KAWASAN PERTAMBANGAN

Carbon emissions are one of the components of greenhouse gas (GHG) emissions in the form of carbon dioxide (CO2) which mainly comes from the use of fossil fuels and various human activities. Based on fossil fuel and industrial emissions data, in 2022 Indonesia ranked as the 6th largest carbon emitting country in the world after China, the United States, India, Russia and Japan, with 728.88 million tons of CO2e total emissions. The Ministry of Industry reported that total GHG emissions from Indonesia's industrial sector reached 238.1 million tons of CO2e in 2022. In the mining industry, GHG emissions originate from deforestation, energy use, processing, and refining, with non-renewable energy use being the largest emitter. GHG emissions from primary mineral and metal production contribute approximately 10% of global GHG emissions related to energy. Each mining industry may have varying primary sources of GHG emissions depending on the type of mine and the final product. Mining industries, as one of the major emitters, must conduct GHG inventories to understand emission sources and develop effective reduction strategies. GHG inventory activities are conducted based on guidelines provided by the Ministry of Environment and Forestry's National Greenhouse Gas Inventory Management Handbook (2012), Book II Volumes 1-4. Efforts to reduce GHG emissions can be undertaken through planting plants that have high carbon absorption and storage capabilities in mine reclamation activities, as well as using New and Renewable Energy (NRE) as an alternative to replace fossil energy.

Evaluating Phase Relations in Molten Oxides for Electrochemical Operating Windows for Selective Metal Reduction

AbstractMolten oxide electrolysis is a promising pathway to decarbonize primary metal production. The oxide electrolyte is less hazardous and eco‐toxic than halides (molten salt electrolysis) and, with the use of renewably generated electricity and an inert anode, oxygen is produced as a by‐product instead of CO2. Building fundamental understanding of electrolytic operating windows requires starting with simple chemistries. Here we investigate a simplified binary oxide system as an electrolyte for titanium oxide reduction to metal. The TiO2−Na2O binary system forms a eutectic, reducing the liquidus temperature over a wide composition range. FactSage 8.1 predictions suggested Ti reduction would become favorable over Na reduction for compositions greater than 0.49 mole fraction TiO2. The prediction was validated by the detection of metallic Ti after electrolysis experiments. However, the reduction efficiency was too low (0.24±0.08 % at −0.1 V vs Ti reference electrode) for the TiO2−Na2O system to be a viable industrial electrolyte for Ti production. Scoping for other binary oxide systems was performed for electrolytic production of two critical metals, tantalum and neodymium. Based on TiO2−Na2O system's predicted behavior, candidate binary oxide systems were identified that contained congruently melting line compounds flanked by eutectic reactions from the ACerS‐NIST Phase Equilibria diagrams database.

Comparative life cycle assessment of copper and gold recovery from waste printed circuit boards: Pyrometallurgy, chemical leaching and bioleaching

Printed circuit boards (PCBs) make up a substantial amount of electronic waste (e-waste) generated annually. Waste PCBs contain high quantities of copper and gold in comparison to natural ores. As such, “urban mining” of waste PCBs to recover these metals is of commercial interest. In this work, we used life cycle assessment to compare the environmental impact of four copper and gold recovery processes. We evaluated pyrometallurgy, chemical leaching, and bioleaching, as well as a hybrid leaching process that uses bioleaching to recover copper and chemical leaching to recover gold. Furthermore, we considered differences in environmental impact based on differences in electricity sources. If electricity comes from fossil fuels, the pyrometallurgical process results in the lowest environmental impact in all impact categories studied. If electricity comes from carbon-free sources, the pyrometallurgical process results in the lowest environmental impact in all categories studied except global warming, where the hybrid leaching process results in the lowest impact. In all cases, metal recovery from waste PCBs leads to lower environmental impact than primary metal production. Our goal is to guide e-waste recyclers towards more environmentally sustainable metal recovery processes and to provide knowledge gaps in the field to guide future research.

Experimental Validation is Always Required for Molten Oxide Electrolysis Laboratory Crucibles

Molten oxide electrolysis (MOE) is a promising electrochemical route to de-carbonize primary and secondary metal production. Developing MOE processes starts with laboratory experiments at temperatures > 1000∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1000\\,^\\circ{\\rm C}$$\\end{document} lasting ~10 hours and requiring long heating/cooling times to protect furnace hardware. Before investigating MOE processes, crucibles must be selected that tolerate the required temperatures while minimizing chemical interactions with the oxide to control melt contamination and contain the melt. Unfortunately no general procedure guiding MOE crucible selection is documented. Here we focus on laboratory crucibles in air for two MOE melts: titania-sodia at 1100∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1100\\,^\\circ{\\rm C}$$\\end{document} and neodymia-boria at 1300∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1300\\,^\\circ{\\rm C}$$\\end{document}. After shortlisting generic crucible materials using Ashby’s method, thermodynamic predictions were made for all-oxide titania-sodia charges using FactSage and cup test experiments were conducted on (i) all-oxide and carbonate charges for titania-sodia and (ii) neodymia-boria charges. While magnesia was predicted to be the best crucible for the titania-sodia melt, alumina was the best choice for both oxide and carbonate charges. The grain boundary networks of both magnesia and YSZ were infiltrated by the oxide and carbonate charges. Platinum was the best crucible for neodymia-boria melts. We show that compositional control during long, high-temperature MOE experiments requires experimental validation for specific chemistries every time.

The limitations of end-of-life copper recycling and its implications for the circular economy of metals

Increasing the recycling of metals reaching their end-of-life (EoL) is a vital circular economy approach to meet the growing demand for metals and reduce reliance on mining. To assess the potential of recycling strategies in fulfilling future metal demand and replacing primary production, we develop a novel dynamic probabilistic material flow analysis (MFA) model. Unlike previous MFA studies, our model explicitly explores the potential of recycling to reduce metal mining activities while considering uncertainties in future EoL collection and recycling rates. Focusing on copper, a critical mineral for low-carbon technologies, the model dynamically estimates the future copper stocks and flows under three different demand scenarios and probabilistic EoL collection and recycling assumptions. Our analysis reveals that the share of EoL secondary supply of overall copper demand, which currently stands at 23 %, will even under the scenario with the lowest future copper demand only be averaging 33.4 % over the next three decades. In addition, even under the most optimistic circumstances with lower than expected copper demand and very high collection and recycling rate growth, the annual share of EoL secondary supply of overall copper demand would only reach 49.6 % in 2050. Thus, primary copper extraction is expected to rise significantly until at least 2040 and under 87 % of all 30,000 modelled outcomes, primary production of copper in 2050 will still be above 2020 production levels. Consequently, we emphasise the need for alternative circular economy strategies beyond recycling, such as demand reduction and mitigating the harmful impacts of primary metal production.

Understanding Scale-Up of High-Current Electrodes

A simple and generic model for the heat distribution in electrodes for primary metal production has been investigated. The equations have been analyzed focusing on understanding the scale-up of electrodes under both direct current (DC) and alternating current (AC) conditions. The analysis provides a theoretical foundation for Westly’s empirical scale-up rule. For graphite and small carbon electrodes, the current-carrying capacity is limited by the ohmic heating, which controls the lateral heat flux and the temperature at the electrode periphery. For these electrodes, the current capacity is higher for DC than for AC. For large carbon or Søderberg electrodes, the electrode current must be limited to avoid large thermal stresses and subsequent breakages, especially in connection with shutdowns or considerable current fluctuations. Thermally, the current capacity is then limited by the maximum temperature difference between the center and the periphery. For this case, AC electrodes can carry more current than DC.

Nd Recovery from Wastewater with Magnetic Calcium Alginate ((1,4)-β-d-Mannuronic Acid and α-L-Guluronic Acid) Hydrogels.

In this study, a magnetic adsorbent material was produced, by environmentally friendly and inexpensive precursor materials, to clean wastewater that may result from primary and secondary rare earth metal (REM) production. Then, the absorption of Nd3+ ions from wastewater was done and this process's kinetic and isotherm models were developed. Thus, the removal of Nd3+ from wastewater with magnetic materials was accomplished, and then, this precious metal was recovered by using different acid media. First, Fe sub-micron particles were successfully produced by the polyol method. To increase the stability of Fe-based particles, their surfaces were covered with an oxide layer, and the average thickness was determined as 16 nm. The synthesized Fe particles were added into the calcium alginate beads and then coated with chitosan to increase the pH stability of the gels. The chemical composition of the gels was determined by Fourier transform infrared spectroscopy, the thermal properties were determined by differential scanning calorimetry, and the magnetic properties were determined by vibrating-sample magnetometer analysis. The magnetic saturation of the hydrogels was 0.297 emu/g. After the production of magnetic calcium alginate hydrogels, Nd3+ ion removal from wastewater was done. Wastewater was cleaned with 94.22% efficiency. The kinetic models of the adsorption study were derived, and isotherm studies were done. Adsorption reaction fitted different kinetic models at different time intervals and the Freundlich isotherm model. The effect of pH, temperature, and solid-liquid ratio on the system was determined and the thermodynamic constants of the system were calculated. After the adsorption studies, Nd3+ ions were regenerated in different acid environments and achieved an 87.48% efficiency value. The removal of Nd3+ ions from wastewater was carried out with high efficiency, the gels obtained as a result of adsorption were regenerated with high efficiency by using acid media, and it was predicted that the gels could be reused. This study is thought to have reference results not only for the removal of REM from wastewater by magnetic adsorption materials but also for the adsorption of heavy metals from wastewater.

Grade and Tonnage Comparison of Anthropogenic Raw Materials and Ores for Cu, Zn, and Pb Recovery

Primary metal production operates with large tonnages and takes advantage of economies of scale. Metal recycled from low-value waste streams, competing in the same global metal market as primary production, will be more competitive by also taking advantage of up-scaling. However, an overview of metal tonnages in low-value waste streams to see upscaling potential needs to be provided in the literature. In response, this study provides estimates of copper, zinc, and lead metal tonnages in waste incineration ash—A major waste stream going to landfills. Metal concentrations and tonnages are compared to tonnages and concentration grades found in ores. Copper, zinc, and lead concentration averages are about 3–5 times lower in ash compared to the worldwide average head grade of ores. Tonnages of metal in the ash generated from waste incineration in European countries bordering the Baltic and the North Sea are about 1/3 of mining metal output from Sweden, a leading mining country in the region. Therefore, incineration ash should be considered a significant potential Cu, Zn, and Pb metal source.

Life cycle assessment of valuable metal extraction from copper pyrometallurgical solid waste

China generates about 20 million tons of solid waste for copper production each year, most of which comes from pyrometallurgy, leading to substantial environmental problems. Extracting valuable metal is a common way of recycling copper pyrometallurgical solid waste (CPSW). However, its environmental effects are still unclear. This paper adopts a cradle-to-gate life cycle assessment to assess the impacts of recycling three main types of CPSW (smelting slag, copper ash, and anode slime). Results show that the prominent contributor to the environmental impacts is electricity consumption. The sensitivity analysis demonstrates that reducing electricity consumption and optimizing the electricity grid mix can reduce the environmental impact. The comparative analysis was conducted to investigate the environmental advantages between CPSW recycling and primary metal production. The results indicate that the impacts of CPSW recycling are 86%, 52%, and 79% lower than that of copper concentrate production, primary copper hydrometallurgy, and primary gold production.

Washing and Extraction of Metals from Two Industrially Contaminated Soils: A Prognostication for Techno-economic Clean up

The extraction and recovery of metals from contaminated soil has become inevitable considering the increasing premium placed on environmental and human health protection as well as predicted shortfalls in primary metal production. In this study, metal extraction from two industrially contaminated soils (Copsa-mica [Rb-So] and Campina [Ro-PH]) were considered for process (column and heap) leaching configuration using different selected chelating substances; ethylene diamine tetraacetic acid [EDTA], ethylene diamine disuccinic acid [EDDS], acetylacetone [Hacac] and citric acid [CA]. The result confirms optimal recovery of EDTA column-induced-Rb-So over chelant-heap induced configuration and was adopted for economic prediction using two possible (60% and 100%) recycled scenarios. The 100% recycled scenario resulted in a viable economic process sufficient enough to offset clean-up cost. Metal separation and recovery from M-EDTA complex could be facilitated with the use of H2S gas precipitated in hydrogen flame combustion. The process economics predicted offered a probable prospect for metal separation from washing liquor.

Towards Understanding the Cathode Process Mechanism and Kinetics in Molten LiF–AlF3 during the Treatment of Spent Pt/Al2O3 Catalysts

Electrochemical decomposition of spent catalyst dissolved in molten salts is a promising approach for the extraction of precious metals from them. This article reports the results of the study of aluminum electrowinning from the xLiF–(1-x)AlF3 melt (x = 0.64; 0.85) containing 0–5 wt.% of spent petroleum Pt/γ-Al2O3 catalyst on a tungsten electrode at 740–800 °C through cyclic voltammetry and chronoamperometry. The results evidence that the aluminum reduction in the LiF–AlF3 melts is a diffusion-controlled two-step process. Both one-electron and two-electron steps occur simultaneously at close (or same) potentials, which affect the cyclic voltammograms. The diffusion coefficients of electroactive species for the one-electron process were (2.20–6.50)∙10−6 cm2·s–1, and for the two-electron process, they were (0.15–2.20)−6 cm2·s−1. The numbers of electrons found from the chronoamperometry data were in the range from 1.06 to 1.90, indicating the variations of the partial current densities of the one- and two-electron processes. The 64LiF–36AlF3 melt with about 2.5 wt.% of the spent catalysts seems a better electrolyte for the catalyst treatment in terms of cathodic process and alumina solubility, and the range of temperatures from 780 to 800 °C is applicable. The mechanism of aluminum reduction from the studied melts seems complicated and deserves further study to find the optimal process parameters for aluminum reduction during the spent catalyst treatment and the primary metal production as well.

Justification of methodical approach to mining and processing efficiency evaluation

The present-day research of ecological and economic methods applied in mineral accessing and mining neglects technical efficiency. Mineral mining mostly uses conventional and proven technologies. These technologies are primarily aimed at reaching the largest possible outputs in mineral production. In the meanwhile, scientists are increasingly being engaged in the theory and practice of economical mathematical validation of engineering solutions for different phases of mineral mining. Enhanced efficiency of mining and processing defines intelligent management of natural resources and has an essential influence on the industry performance. The industry is imposed with certain requirements and constraints that also represent influences on technical efficiency of primary metals production. Technological advance of a mine with regard to ecological and economic evaluation of flow processes takes shape as a generalized model of activities aimed at higher profit return, increased extraction of mineral resources from the subsoil, cut-down cost of mining and processing, and at reduced waste and harmful emission. The authors assess the open pit mining efficiency as a function of concentrate production cost as a case-study of Pokrovski GOK, Ukraine. Statistical correlation of the production technology and economy and the produced ore flow quality is determined. A blending procedure is proposed for manganese ore from two groups of open pits to ensure the largest extractability of the useful component at the minimum cost of stripping. Preset quality ore should be accumulated at a processing plant for the concentrate production, with follow-on re-adjustment of the process circuits to ore with another content of metal. Free market economy has a material effect on production performance in the mining and processing industry, first of all, on the volume of products sold.

Solving multifunctionality in the carbon footprint assessment of primary metals production: Comparison of different approaches

Multifunctionality is a recurring issue in the life cycle assessment (LCA) of primary metals production, as one metal is often co-produced with other metals. In this context, this study aims at i) reviewing the approaches actually implemented in the literature for solving multifunctionality in the context of the LCA of primary metals co-production; ii) comparing the currently existing multifunctionality-solving approaches as defined by the ISO hierarchy, considering the carbon footprint assessment (in a life-cycle perspective) of copper (Cu), zinc (Zn), lead (Pb) and silver (Ag) co-production through the implementation of on-site “mine-to-metal” technologies at pilot scale in a Spanish mine; iii) discussing the implications associated with the use of these different approaches in the context of primary metals co-production and the extent to which they may affect the assessment of the environmental performances of metals. Overall, the allocation approach stands for the first option for solving multifunctionality in the LCA of metals co-production based on the review of 27 studies; despite the ISO hierarchy recommends the use of allocation as last resort. Based on a representative set of primary data drawn from on-site trials at a pilot scale, the potential climate change impacts induced by the co-production of 1 ton Cu and 6 tons Zn cathodes along with 2.65 tons Pb and 0.045 ton Ag precipitates are calculated to amount to 90,324 kg CO2-eq in a life cycle perspective. Depending on the multifunctionality-solving approach, the apportionment of these impacts to each co-product shows significant discrepancies. The implementation of partial subdivision combined with market prices allocation attributes most (80%) of the impacts to Zn and Ag. The use of allocation approaches attribute the largest share of impacts to Zn (62%) and Pb (27%) when considering a mass criterion; while the impacts are primarily attributed to Ag (respectively 48% and 45%) and Zn (respectively 30% and 33%) when considering economic criteria (respectively market prices and production costs). In terms of representativeness, the use of partial subdivision shall be considered as a more representative approach for solving multifunctionality than the mere application of allocation. Moreover, the results obtained through the application of economic allocation are considered more consistent than those obtained by mass allocation in this case study; while the use of production costs may be seen as an alternative for overcoming the limits associated with market prices. Finally, the use of system expansion shows that the recovery of Zn, Pb and Ag in addition to Cu potentially avoids 25% of the total climate change impacts. The approach implemented to solve multifunctionality largely influences the estimated impacts of each co-produced metal, subsequently with potential large implications for the footprints of products and sectors using these metals. The way multifunctionality is solved shall therefore be transparently reported in the scope of LCA studies, with privileging subdivision whenever possible.

Integrated LCA-MFA Framework for Gold Production from Primary and Secondary Sources

Secondary production of non-ferrous metals produced from waste can reduce the environmental burdens associated with primary production and contribute to achieving sustainable development goals. At the present condition, secondary metal manufacturers lack decision support system through an appropriate impact assessment framework. Thus, this paper presents an integrated impact assessment framework for primary and secondary metal production, using the material flow analysis and life cycle assessment. The non-ferrous metal analysed in this study is gold as a case study for the precious metal recovery from anode slime. The sensitivity analysis showed that using gold produced from combined primary and secondary sources generates significantly less environmental impact (e.g. climate change, freshwater ecotoxicity, and mineral resources depletion) in comparison with only primary metals. Further exploration of increasing separation and recovery efficiency of secondary production only suggested a marginal decrease in the overall impact.

Transparency on greenhouse gas emissions from mining to enable climate change mitigation

The climate change impacts of mining are often not fully accounted for, although the environmental impact of mineral extraction more generally is widely studied. Copper mining can serve as a case study to analyse the measurable pathways by which mining contributes to climate change through direct and indirect greenhouse gas emissions. For example, mining, processing and transportation require fuel and electricity, and the decomposition of carbonate minerals, employed to reduce environmental impacts, also releases carbon dioxide. Overall, we estimate that greenhouse gas emissions associated with primary mineral and metal production was equivalent to approximately 10% of the total global energy-related greenhouse gas emissions in 2018. For copper mining, fuel consumption increased by 130% and electricity consumption increased by 32% per unit of mined copper in Chile from 2001 to 2017, largely due to decreasing ore grade. This trend of increasing energy demand to produce the same quantity of some metals compounds the problems of increased metal demand due to the pressures of new technologies and increasing population. For green technologies to be implemented effectively, it is necessary that the mining industry and regulators accurately and transparently account for greenhouse gas emissions to implement mitigation strategies. Direct and indirect greenhouse gas emissions from mining for green technologies need to be accurately and transparently accounted for, as highlighted by a case study of Chilean copper mining.

Energy modeling and eco impact evaluation in direct metal laser sintering hybrid milling

This paper presents an analytical model of energy consumption for Direct metal laser sintering hybrid milling (DMLS-HM) additive manufacturing (AM) of stainless steel 316L. The model is used to quantify energy consumption during production of a defined geometry with DMLS-HM process and compared with energy consumption in electron beam melting (EBM) and conventional machining (CM). The solid-envelope ratio (α) was used to quantify energy consumption and eco impact of the three manufacturing processes on three different geometry models. The Gabi database and other published literature were used to establish energy consumption during primary metal production and material shaping processes. It was found that solid-envelope ratio (α) has more impact on the energy model of the additive processes than on the subtractive machining. On average, the percentage change in α is equal to the percentage change in energy consumed by DMLS-HM and EBM. The CM process had very little average change of 1.5% compared to the major changes in α. The DMLS-HM process showed dominant energy consumption during the part production stage with an average 84% more than EBM and CM processes. However, the CM was dominant in energy consumption during the primary production stage with an average 70% more energy than DMLS-HM and EBM processes. The novel outcomes of this research will contribute to the understanding of basic physics of energy consumption in AM and can be used in setting sustainable manufacturing goals. Moreover, energy consumption in metal AM also influences mechanical properties and microstructure of produced parts, so this work will further enhance prediction of their quality and service life. DMLS-HM is recently being introduced for industrial applications such as mold and tool manufacturing due to its capabilities in building free form and complex shapes that are otherwise challenging to manufacture by conventional methods.

Discrete-Point Analysis of the Energy Demand of Primary versus Secondary Metal Production.

The metal industry consumes large amounts of energy and contributes significantly, up to 10%, to global greenhouse gas (GHG) emissions. Recycling is commonly included among the most viable options for mitigating the climate forcing of metal production by replacing primary production. However, the recycling rates of metals are still incomplete and, in particular, do not exist for most specialty metals. Our empirical analysis of 48 metals shows that their recycling is mainly impeded by their low concentrations. In many cases, the metal concentration in end-of-life products is lower than that in natural ores. This phenomenon inevitably raises the question of the extent to which recycling can be conducted without losing its mitigating effects on climate change. We answer this question for two example metals, tantalum and copper, within the scope of Germany, a leader in recycling. For tantalum, the results show that a further increase in the end-of-life recycling rate (EOL-RR) could contribute to minimizing the overall energy consumption and GHG emissions, despite its low concentrations in end-of-life products. The energy requirements for recycling copper from end-of-life products already reach the magnitude of those for primary production. A further increase in EOL-RR must be examined in detail to ensure mitigating effects on climate change.

Recycling of spent NiMH batteries: Integration of battery leach solution into primary Ni production using solvent extraction

The utilization of existing metallurgical infrastructure and integration of secondary process streams into primary metals production can provide advantages over separate recycling plants. This paper focuses on the integration of a pregnant leach solution (PLS) into a nickel production plant that contains Ni, Co, Zn, Mn, Fe, Al and Cd ions, derived from a NiMH recycling stream. The solution composition highlights the challenge related to spent battery investigations, as although toxic Cd is not present in NiMH battery chemistries, it ends up into the battery waste collection and prevents direct integration of the battery waste into the primary process. The aim of the study is to remove Zn, Fe, Al, Mn and Cd ions from the PLS, so that the Ni and Co remaining in solution could be integrated into the nickel production process. A two-step solvent extraction process using Di-2-ethylheyxl phosphoric acid (D2EHPA) was developed. In the first step, Zn, Al and Fe were removed at pH 1.5, whereas in the second step Cd and Mn were removed at pH 2.3. Different process parameters (pH, O/A ratio, temperature, extractant concentration, kinetics) were optimized at each step of the solvent extraction. The purified and fully integrable PLS was found to contain Ni ~28 g/L and Co ~3.7 g/L.

Critical Metals Ga, Ge and In: Experimental Evidence for Smelter Recovery Improvements

High-tech metals, including Ga, Ge and In, are critical for the performance of electrical and electronic equipment (EEE). None of these three metals exist in mineable levels in natural minerals, and thus their availability and production are dependent on the primary and secondary base metals (including Zn, Al and Cu) production. To secure the supply of high-tech metals in the future, their behavior, including distribution coefficients (LCu/s = [wt% M]in copper/(wt% M)in slag), in primary and secondary processes need to be characterized. This study reports three series of copper-slag distribution experiments for Ga, Ge and In in simulated secondary copper smelting and refining process conditions (T = 1300 °C, pO2 = 10−9–10−5 atm) using a well-developed drop–quench technique followed by EPMA and LA-ICP-MS analyses. This study shows how an analytical technique more traditionally applied to the characterization of ores or minerals can also be applied to metallurgical process investigation. The LA-ICP-MS analysis was used for the first time for measuring the concentrations of these minor elements in metallurgical glasses, i.e., slags, and the results were compared to the geological literature. The distribution coefficient of indium increased as a function of decreasing oxygen partial pressure from 0.03 to 10, whereas the distribution coefficient of gallium was 0.1 at 10−9 atm and decreased as the pO2 increased. The concentrations of gallium in slags were between 0.4 and 0.6 wt% and germanium around 1 ppm. Germanium was vaporized almost entirely from the samples.

RecoDust\u2014An Efficient Way of Processing Steel Mill Dusts

RecoDust is believed to be an efficient way of processing steel mill dusts to produce reusable secondary raw material resources. The rising costs of the steel production process and the increasing public attention towards environmental protection have caused steel plants worldwide to focus on emission-reduction processes and circular economy. As a reusable secondary raw material resource, the steel mill dust contains a high amount of iron and zinc. Nowadays, most of the steel mill dusts are processed under the Waelz-Process. However, this process is limited or impossible without additional dust treatment and can only be operated economically with zinc contents over 20 wt%. In the future, RecoDust in combination with dry slag granulation will become an efficient technique for processing lower zinc-containing materials of a steel mill. A challenging area in the field of RecoDust is the melting/reduction phase to separate volatile components and the slag treatment. A previous study was limited to the recovery of zinc. This paper compares the energy consumptions of the primary metal production to the recycling and of the RecoDust process to the Waelz-Process and outlines a new approach to RecoDust slag treatment.