Secondary Metal Production Research Articles

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.

Econometric modeling for the influence of economic variables on secondary copper production in India

The stocks and flows of primary metal resources, and the estimates of so generated secondary scrap metal flows are tracked and analysed utilizing the traditional analytical method of ‘material flow analysis’. However, the scrap availability and hence the secondary metal production is also influenced by fluctuating economic conditions. Here we utilize the autoregressive distributed lag approach to model the influence of selected economic variables on secondary metal production and hence the scrap availability in the country. We find electricity index, mining index, and electric power generation and distribution correlate with secondary copper production in long-run; and electricity index correlate with secondary copper production in short-run. A 1% increase in electricity index initially leads to 1.76% drop in secondary copper production in short-run, and 3.69% increase in secondary copper production in long-run. A 1% increase in both mining index, and electric power generation and distribution leads to 4.57% and 5.18% decrease in secondary copper production in long-run respectively. The CUSUM and CUSUMSQ charts show the developed ARDL model to be stable over time. Based on the model dependence, we suggest that the policy makers shall devise policies towards reducing copper mining activities thereby encouraging stakeholders to focus on effective collection and efficient recycling of copper towards conservation of natural metal resources.

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.

The environmental performance of enhanced metal recovery from dry municipal solid waste incineration bottom ash

This study assesses the environmental performance of the municipal solid waste (MSW) incineration bottom ash (IBA) treatment plant in Hinwil, Switzerland, a large-scale industrial plant, which also serves as a full-scale laboratory for new technologies and aims at an optimal recovery of metals in terms of quantity and quality. Based on new mass-flow data, we perform a life cycle assessment that includes the recovery of iron, stainless steel, aluminium, copper, lead, silver and gold. Fraction-specific modelling allows for investigating the effect of the metal fraction quality on the subsequent secondary metal production as well as examining further metal recycling potentials in the residual IBA. In addition, the implications on the landfill emissions of IBA residues to water were quantified. The impact assessment considered climate change, eco- and human toxicity and abiotic resource depletion as indicators.Results indicate large environmental savings for every impact category, due to primary metal substitution and reduction of long-term emissions from landfills. Metal product substitution contributes between 75% and >99% to these savings in a base scenario (1′000-year time horizon), depending on the impact category. Reductions in landfill emissions become important only when a much longer time horizon was adopted. The metal-based analysis further illustrates that recovering heavy non-ferrous metals – especially copper and gold – leads to large environmental benefits. Compared to the total net savings of energy recovery (215 kg CO2-eq per tonne of treated waste, average Swiss plant), enhanced metal recovery may save up to 140 kg CO2-eq per tonne of treated waste.

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.

The energy needed to concentrate minerals from common rocks: The case of copper ore

A way to assess today's mineral patrimony is to evaluate how much mining energy is saved today because of having concentrated mines instead of finding the minerals dispersed throughout the crust. This can be assessed through the so-called exergy replacement costs (ERC), which are a measure of the exergy required to extract and concentrate minerals from barerock. Previous studies evaluated such exergy using a theoretical approach. In this paper, from a mineral processing point-of-view through a model developed with HSC Chemistry 9.4.1, we calculated the energy needed to concentrate copper from common rocks at average crustal concentrations. In the model, current state-of-the-art technologies for copper concentration were considered. The results were then compared to the theoretical value obtained before for the ERC of copper and helped to update it. The updated ERC value is of one order of magnitude greater than the original one. This difference in magnitude enhances, even more, the issue of ore grade decline in terms of the associated spiraling energy required for mining. It also reveals the importance of valuing properly the mineral heritage of nations and the effort that should be placed for increasing secondary metal production.

Removal of copper from cattle footbath wastewater with layered double hydroxide adsorbents as a route to antimicrobial resistance mitigation on dairy farms

Copper and zinc are routinely used in livestock antimicrobial footbaths in commercial farming. The footbath mix is a cost to farmers, and the disposal of spent footbath into slurry tanks leads to soil contamination, as well as the potential for antimicrobial metal resistance and co-selection. This study assesses the potential to mitigate a source of antimicrobial metal resistance in slurry tanks while recovering copper and zinc from spent cattle footbaths. This is the first study in literature to investigate the potential of recovering copper from cattle footbath solutions via any method. The sorbent, Ca2Al-EDTA Layered Double Hydroxides (LDH), were used to remove Cu2+ from a Cu2SO4·5H20 solution at different temperatures. The maximum Cu2+ uptake from the Cu2SO4·5H20 solution was 568 ± 88 mg g−1. Faster and higher equilibrium uptake was achieved by increasing the temperature of the solution. The sorbent was found to be effective in removing copper and zinc from a commercially available cattle footbath solution (filtered footbath solution Cu2+ uptake 283 ± 11.05 mg g−1, Zn2+ uptake 60 ± 0.05 mg g−1). Thus, this study demonstrates the opportunity for a completely novel and potentially economically beneficial method of mitigating antimicrobial resistance in agriculture and the environment, while also providing a new valuable copper and zinc waste stream for secondary metal production.

PROFESSIONAL RISK OF THE DEVELOPMENT OF DERMATOLOGICAL DISEASES IN WORKERS OF PRODUCTION OF SECONDARY PRECIOUS METALS

Introduction. Working conditions in the metallurgical industry are characterized by the impact of unfavorable production factors on the workers of the complex. This leads to a high level of the occupational and general morbidity rate in metallurgists. The production of secondary metals is an intensively developing direction of metallurgy, which determines the urgency of studying the labor and health conditions of workers in this industry at the present stage. Material and methods. A comprehensive assessment of the working conditions of the workers of Shchelkovsky Secondary Precious Metals Plant was conducted. The occupational risk for the health of the core occupations of secondary precious metals was quantified, there were estimated the profile of occupational risk and the main unfavorable factors of the production process, making a significant contribution to the formation of dermatological morbidity of personnel. Results. Priority occupational risk factors for the formation of dermatological diseases in workers of secondary precious metals production is the impact of a multicomponent industrial aerosol and a heating microclimate. The chemical factor contributes a significant share contribution (20 - 25%) to the occupational risk profile and gives high indices of individual occupational health risks for workers in the main occupations of this production. The occupational risk of the incidence rate with a temporary disability (TD) in the enterprise as a whole is regarded as super-high. The incidence of diseases of the skin and subcutaneous tissue in workers reaches the highest level in the main production divisions and makes up in the structure of the total morbidity rate with TD of 12.3 to 14.5%. Discussion. The personal occupational risk of the secondary production of precious metals is determined by a significant proportion of employees in the core occupations with harmful working conditions on a chemical factor. The specific labor conditions of the main professional groups determine the high level of the relative risk of dermatological diseases (RR = 2.31), and the etiological share of occupational factors in their formation ranges from 56.79 to 88.84%, which proves their production conditionality.

Metal Dissipation and Inefficient Recycling Intensify Climate Forcing.

In the metals industry, recycling is commonly included among the most viable options for climate change mitigation, because using secondary (recycled) instead of primary sources in metal production carries both the potential for significant energy savings and for greenhouse gas emissions reduction. Secondary metal production is, however, limited by the relative quantity of scrap available at end-of-life for two reasons: long product lifespans during use delay the availability of the material for reuse and recycling; and end-of-life recycling rates are low, a result of inefficient collection, separation, and processing. For a few metals, additional losses exist in the form of in-use dissipation. The sum of these lost material flows forms the theoretical maximum potential for future efficiency improvements. Based on a dynamic material flow analysis, we have evaluated these factors from an energy perspective for 50 metals and calculated the corresponding greenhouse gas emissions associated with the supply of lost material from primary sources that would otherwise be used to satisfy demand. A use-by-use examination demonstrates the potential emission gains associated with major application sectors. The results show that minimizing in-use dissipation and constraints to metal recycling have the potential to reduce greenhouse gas emissions from the metal industry by about 13-23%, corresponding to 1% of global anthropogenic greenhouse gas emissions.

Estimating the quantities of critical metals embedded in ICT and consumer equipment

The manufacturing of Electrical and Electronic Equipment is dependent on the supply of several technology metals that are classified as critical. Recycling is key strategy to secure the long-term supply of these metals. To determine the recycling potential, the mass and the economic value of nine metals and metal families contained in information and communications technology and consumer equipment sold in Germany in 2007 and 2012 were estimated under consideration of uncertainties. The study focused on the critical metals and metal families cobalt, gallium, indium, palladium and rare earth elements (REE), as well as tantalum and the lead metals tin, gold and silver. The estimation was based on data on sales volumes of 126 products, on the mass or surface of the assemblies containing the target metals (populated printed circuit boards, panels and backlighting systems of flat displays, batteries and magnets in drives and loudspeakers) and on the mass fraction of metal in the assemblies. The estimations show that gold is by far the most important carrier of economic value. Flat televisions, desktop computers, laptops and smartphones contain a large part of the target metals. Recommendations for improving recycling were formulated. Besides the technological barriers, enhancing or enabling the recovery of indium, gallium, REE and tantalum requires the creation of economic incentives, because it is very unlikely that the revenues expectable from the production of secondary metals can cover the process costs.

Analysis of CO2 emissions reduction potential in secondary production and semi-fabrication of non-ferrous metals

Industrial sector growth in developing countries requires the provision of alternatives to guarantee sustainable development. Improving energy efficiency and fuel switching are two measures to reduce CO2 emissions in the industrial sector, with natural gas and low-carbon electricity as the most feasible options in the short term. In this work, a linear programming optimization model has been developed to study the potential of energy efficiency improvement and fuel substitution for CO2 emissions reduction, at national level in the non-ferrous metals industry. The energy resource/end-use device allocation problem in secondary metal production and semi-fabrication has been modeled. Using this model, the particular case of Colombia, where low-carbon electricity is available, has been studied. By improving energy efficiency, energy use and CO2 emissions can be reduced significantly, 73% and 72%, respectively, at negative costs. Further CO2 emissions reductions, up to 88%, are possible with fuel switching to low-carbon electricity, increasing the costs for the energy system; however, cost reductions caused by energy efficiency improvement outweigh cost increments of fuel switching. Benefits achieved with fuel substitution using low-carbon electricity can be lost if hydropower is not available; in such a case, efficient natural gas-fired end-use devices are preferable.

Recycling policy in the european union

Recycling in the European Union (EU) has benefited from R&D efforts and strict environmental regulations of the EU’s members. Thanks to the adoption of sustainable development policies by the EU’s European Institutions, economic incentives are expected to further strengthen the recycling industry. Moreover, the historical accumulation of non-ferrous metals in Europe will likely enhance secondary metal production. Also contributing to EU recycling is mining in East European countries and the resulting industrial waste. The rate of growth of the recycling industry is expected to approach double digits for at least this decade.

The future of recycling

Recycling in general and metal recycling in particular, many believe, enjoy a very bright future. As resource depletion, environmental concerns, and other factors drive primary production costs up, the relative importance of recycling in supplying the material needs of society will grow. This optimistic view, however, may paint an overly rosy and misleading picture. A large portion of secondary metal production is based on the recycling of new scrap, which is constrained far more by the available supply of new scrap than by metal prices or recycling costs. Secondary production from old scrap is more sensitive to costs and prices, and so would benefit from a rise in metal prices. History, however, indicates that the cost-reducing effects of new technology have over the past century more than offset the cost-increasing effects of depletion, causing real metal prices to fall. In recent decades, this decline in prices has continued despite government policies that are increasingly forcing firms to cover their environmental costs. While this favorable trend may not continue forever, it does suggest that secondary producers will have to pursue aggressively new technologies and other innovations that reduce their costs as fast or faster than primary producers if they hope to expand their future share of total metal production.

RECYCLING METALS FOR THE ENVIRONMENT

▪ Abstract Society uses metals derived from primary and secondary sources. Secondary sources include all metals that have entered the economy but no longer serve their initial purpose. The environmental benefits of increasing reliance on secondary metal production include conserving energy, landscapes, and natural resources, and reducing toxic and nontoxic waste streams. A variety of technologies are used to recover and process metals from waste streams and their use for metal production influences the amount of secondary metal that reenters the system. Environmental regulation also affects secondary metal production through laws that control emissions and govern the classification and treatment of metal-loaded wastes. Industry must develop better technology to isolate and recover maximum value from metals in waste streams, and governments must institute policies that remove barriers to their economically and environmentally sound recovery. Only through a concerted effort can society recover a maximum amount of metal from the industrial/social system to benefit the environment.

The implications of the Basel Convention for developing countries: the case of trade in non-ferrous metal-bearing waste

Abstract The decision to introduce a ban on trade in hazardous waste with secondary values between Annex VII countries (the OECD, EU and Liechtenstein) and Annex VIII countries (other signatories) could have important implications for developing countries. The specific case of non-ferrous waste has been chosen for analysis since it is an important component of waste trade flows and since a number of reports have been written which argue that the ban may have adverse economic and environmental effects for a number of developing countries. The study examines some of the relevant trade data as well as the underlying economic factors behind the trade. In particular, the generation of non-ferrous metal (NFM)-bearing waste, the use of non-ferrous metals in manufacturing sectors, and the production of secondary non-ferrous metals in the two areas will be examined. The main findings of the paper are that: metal-bearing solid waste generation amongst developing countries is lower in absolute terms, but the rate of growth is much higher than amongst OECD countries; many developing countries are exhibiting much faster rates of growth in demand for non-ferrous metal than OECD countries due to shifts in the sectoral composition of their economies; international trade in NFM-bearing waste and scrap is relatively significant for some metals, but those types of waste most likely to be affected by the ban do not appear to be important parts of this trade; and, imports of non-ferrous metal waste and scrap help to explain the production of secondary metals, thus indicating that at least some of the trade in waste is motivated by demand for the waste for reclamation. The report concludes that while the ban is far from being an ideal environmental policy instrument, it must be understood as a reflection of both market failures (in the market for hazardous waste treatment and reclamation) and policy failures (in previous efforts to control adverse effects from the trade). If appropriate criteria are applied (mainly waste classifications and Annex classifications) then the environmental implications of the ban may be positive and the negative economic consequences quite small. However, given the rate of growth in generation in many of the Annex VIII countries, such benefits are likely to be slight relative to the problem of the treatment and reclamation of waste generated domestically. Thus, it is argued that if the ban is to be introduced, the dormant `positive' measures in the Convention related to financial and technical assistance need to be revived.

Analysis of non-ferrous metals

Abstract

Production of secondary metals in 1909

Production of secondary metals in 1909