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The co-smelting of electronic waste (e-waste) in copper/lead pyrometallurgical processes is widely recognized as the preferred solution for sustainable development. However, aluminum and halogen elements in e-waste causes new challenges. To address this, the slag chemistry of high Al2O3-containing slag was studied, and the distribution behaviors of Au, Ag, Sn, and other elements in the copper alloy/slag/gas system were investigated in the presence of halogen elements (F/Cl/Br) using the equilibration method. The industrial practice of electronic waste smelting was modeled using METSIM, and the material and energy balances of one industrial process were obtained. Under the conditions of electronic waste smelting, the solubility of Al2O3 in the FexO–SiO2–Al2O3–CaO slag system decreased with increasing CaO content. When the CaO content was 20 wt%, and the Fe/SiO2 mass ratio was 0.62–0.95, the solubility of Al2O3 in the slag reached 20 wt%. When 1%–10% CaF2 was added, 93% of Au entered the metal phase. When the same amount of CaCl2 or CaBr2 was added, up to 32% Au entered the gas phase. When CaF2 was added to the system, 22%–49% of Ag entered the gas phase. However, when CaCl2 or CaBr2 was added, 3%–34% of Ag entered the gas phase. The proportion of tin in the gas and slag phases increased with increasing temperature or the addition of halides. The METSIM simulation results showed that under optimized conditions, the crude copper contained more than 90 wt% copper, the discharged slag contained approximately 0.5 wt% copper, and the recovery rates of copper, gold, and silver were ≥98%. The heat generated from raw materials and fuel accounted for the largest part of the heat income, representing 65.32% of the total.

In this study, we investigate the effect of low-temperature leaching modes to leach copper and silver from secondary copper electrolytic refining slime with sulfuric acid solution. Promising fields for intensification of the leaching process of secondary copper electrolytic refining slime , namely preliminary oxidizing roasting and microwave processing, are determined. The influence of firing temperature (500°C–800°C) on the characteristics of calcines and recovery of copper and silver into sulfuric acid solution in the presence of hydrogen peroxide are studied. The formation of new phases in a temperature range of 500°C–800°C, namely silver-containing copper hydroxosulfate, lead- containing barite, and copper oxide, at firing temperature more than 700°C is revealed. The maximum copper and silver recovery into the leaching solution from the slime is 96.40% and 84.10%, respectively. Regression equations of the effect of microwave treatment power (300–530 W) and duration (5–9 min) on copper and silver recovery into the leaching solution are determined via mathematical planning of the experiment. In the studied factor-variation intervals, the maximum recovery of copper and silver into the leaching solution is 96.74% and 35.72%, respectively. [ABSTRACT FROM AUTHOR]

In this study, the effect of copper and silver low-temperature leaching from secondary copper electrolytic refining slime with the sulfuric acid solution was investigated. Herein, the relevance of copper and silver collective recovery from secondary copper electrolytic refining slime was verified at the initial stage of their processing. Additionally, characterization of the secondary copper electrolytic refining slime sample was explored in detail. It was found that the main phases are PbSO4 (25.0%), SnO2 (20.0%), and BaSO4 (13.1%), and copper (9.62%) was distributed between its conventional phases (Cu2O and Cu2Se) and complex compounds (CuPbSO4(OH)2, Cu5(SO4)2(OH)6·4H2O). Moreover, silver (5.6%) was in metallic form by 73.2%, while the remaining amount is in AgCl, Ag2Se, and Ag2Te compounds. The formation enthalpies of the new phases (CuPbSO4(OH)2, Cu5(SO4)2(OH)6∙4H2O) were calculated at their crystalline structures based on the electronegativity concept. Thermodynamic analysis of the slime–H2SO4 and slime–H2SO4–H2O2 systems was conducted to substantiate the probability and conditions of the slime component low-temperature hydrometallurgical opening because of the odd qualitative or quantitative slime composition. Technological studies confirmed the possibility of copper and silver collective leaching with the sulfuric acid solution in the presence of an oxidant at > 95% and > 23%, respectively. [ABSTRACT FROM AUTHOR]

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Copyright of Mining & Metallurgy (10057854) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pyrometallurgical processes have been widely recognised as the preferred technology for E-scrap recycling, and E-scrap smelting is usually accompanied by the formation of high-Al 2 O 3 -content slag. However, this slag can cause problems, such as refractory wear and even accelerated failure. Therefore, the corrosion mechanism of magnesia-chrome and alumina-chrome refractories in contact with FeO x -SiO 2 -CaO-Al 2 O 3 smelting slag was experimentally studied in the range of 1300–1400 °C, in air (p O2 = 0.21 atm) and at p O2 = 10-7 atm. The results showed that refractory-component dissolution and new phases formation were the major causes of refractory degradation. The dissolution of the refractory components increased along with both increasing temperature and decreasing Al 2 O 3 concentration in the initial slag. When decreasing the p O2 , the dissolution of MgO and Al 2 O 3 into the slag slowed down. New phases such as forsterite, anorthite, and spinel were detected at the interface between the slag and the bulk refractory. The formation of forsterite accelerated the refractory wear, whereas the newly formed (MgO,FeO)·(Cr 2 O 3 ,Fe 2 O 3 ,Al 2 O 3) spinel phase acted as a protective layer against further corrosion. A lower Al 2 O 3 concentration in the slag and a higher smelting temperature both densified the formed spinel layer. Additionally, a high oxygen partial pressure was beneficial to the formation of spinel in the magnesia-chrome refractory corrosion experiments. However, a low oxygen partial pressure was favourable for the formation of spinel on the surface of the alumina-chrome refractory materials. This study provides useful information for designing refractory materials and optimizing the processing parameters of E-scrap smelting. [ABSTRACT FROM AUTHOR]

Various types of waste, including dusts, are produced in the pyrometallurgical production of copper from secondary raw materials. According to the European Waste Catalogue and Hazardous Waste List, dusts from secondary copper production are classified as hazardous waste. In secondary copper production 3.87 million tons of copper were produced worldwide in 2017. The dusts are produced in the following thermal operations: reduction of the melt in the shaft furnace (shaft furnace dust), converting (converter dust), and pyrometallurgical refining (refining dust). These dusts contain significant amounts of heavy metals (Zn, Pb, and Sn) in oxidic forms. The dusts are regarded as secondary raw materials, and it is necessary to look for ways of extracting these heavy metals. The aim of this work was to characterize the individual types of dust and determine their quantitative and qualitative composition. The content of heavy metals in copper shaft furnace dust is (52.16% Zn, 19.33% Pb), in copper converter dust (32.40% Zn, 14.46% Pb), and in refining dust (32.99% Zn).

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The application of Nerin Recycling Technologies (NRT) in electronic waste (E-waste) smelting was introduced in this study, and the material and energy balance was calculated based on the practical data with the METSIM software (METSIM International, USA). The main results are as follows: (1) the optimized processing parameters in the NRT smelting practice were the E-waste feeding rate of 5.95 t/h, oxidation smelting duration of 3.5 h, reduction smelting duration of 0.5 h, oxygen enrichment of 21–40 vol.%, oxygen consumption of 68.06 Nm3/ton raw material, slag temperature of 1280 °C, slag composition: Fe/SiO2 mass ratio of 0.8–1.4, CaO, 15–20 wt.%, Cu in crude copper ≥ 95 wt.%, Cu in slag, 0.5 wt.%, recovery of Cu, Au, and Ag ≥ 98%; (2) 98.49% Au, 98.04% Ag, 94.11% Ni, and 79.13% Sn entered the crude copper phase in the smelting process, 76.73% Pb and 67.22% Zn volatilized to the dust phase, and all halogen elements terminated in the dust and off-gas; (3) total heat input of the process was 79,480 MJ/h, the energy released by chemical reactions accounted for 69.94% of the total, and heat from fuels burning accounted for 33.04%. The energy brought away by the off-gas was 38,440 MJ/h, which was the largest part in heat output. The heat loss with the smelting slag accounted for 28.47% of the total.

The subject of interest in this study was lead cementation with zinc from solution after conventional agitate acidic leaching of converter dust from secondary copper production. The kinetics of lead cementation from an acid solution of lead acetate using zinc powder was studied. The optimal cementation conditions for removing lead from the solution were determined to have a stirring intensity of 300 rpm, a zinc particle size distribution mm and an ambient temperature. Under these conditions, an almost 90% efficiency in removing lead from solution was achieved. The cementation precipitate contains Pb, and a certain amount of Cu. Lead is present in the cementation precipitate in the PbO, Pb5O8 and Pb(Cu2O2) phases. The solution after cementation was also refined from copper. The solution can be used for further processing in order to obtain a marketable Zn-based product. The resulting cementation precipitate can be further processed and modified to obtain a lead-based product. A kinetic study of the process of lead cementation from solution was also carried out. Based on experimental measurements, the value of apparent activation energy (Ea) which was found to be ~18.66 kJ·mol−1, indicates that this process is diffusion controlled in the temperature range 293–333 K.

China is the largest producer and consumer of refined copper in the world. The large amount of copper consumption not only creates added pressure surrounding resource availability but also causes prominent environmental problems. Although copper can be recycled to alleviate resource pressure, there are significant differences between mining primary copper and recycling scrap copper in view of resources, energy consumption, and pollution emissions. These factors were analyzed to better understand the total environmental effects of refined copper from extracting primary ore and recycling scrap copper. The results of this analysis showed that the most serious environmental impacts of refined copper were human toxicity, abiotic depletion potential, and global warming potential. The environmental impacts were mainly caused by the mining and smelting of primary copper by pyrometallurgy. For secondary copper, refining and electrolysis were the main factors. Thus, these main processes, which cause major environmental impacts, should be promoted technologically. According to the results, the total environmental impact of secondary copper was only 1/8 that of the primary copper production process, which indicates that regeneration has better environmental benefits. Furthermore, the sensitive analysis showed that electricity was the most sensitive factor of both technologies. By optimizing the energy structure and increasing the proportion of regeneration, can also reduce the environmental impact. It was suggested that energy structure should be improved and secondary copper should be given more attention and be developed vigorously. Finally, ways to reduce the environmental impact of primary copper and secondary copper industries were recommended. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The recycling of copper cables wastes has as main objective the recovery of copper. The effectiveness of this operation is guaranteed by the following factors: infrastructure able to collect, select and sort these wastes; a market capable to capitalize copper recovered from cables wastes to their true value; processors with equipment and technologies to achieve maximum recycling yields without negative effects on the environment. The most effective chains for wastes recycling may be considered those which use the copper recovered in wires and rods production. So is possible the design and operation of specialized flows for production of secondary copper with high purity. Contrary, a less efficient management of these wastes lead to the poor collection and mixed storage mixed with other types of copper scrap. In this case the copper wire can be recycled effectively to obtain copper-based alloys if special measures are applied at the recycling. The paper analyzes the driving forces that motivate the recycling of copper cables wastes. Also are presented the smelting experiments for obtaining high quality secondary copper and secondary brass from feed containing copper recovered from cables wastes into electric crucible furnace. The results are analyzed in terms of recovery yield and chemical composition.

Copper is a strategic resource to support China's low carbon transition and economic development. China must meet its high copper demand with its limited copper reserve, indicating that it is essential to promote sustainable copper resource management by encouraging secondary copper supply. However, both primary and secondary copper production result in significant environmental impacts. Thus, it is urgent to evaluate such impacts so that appropriate mitigation pathways can be identified. This study conducts life cycle assessment (LCA) at the corporate level to measure the environmental impacts of both primary and secondary copper production. Results show that the total environmental impact from secondary copper production accounted for 7.7%–14.3% of that from primary copper production. Human carcinogenic toxicity is the most significant environmental impact for both primary and secondary copper production. Electricity is the dominant contributor to such environmental impacts. Factors that lead to such environmental impacts are also identified, suggesting that it is critical to increase secondary copper production. Finally, several policy recommendations are proposed to facilitate sustainable copper resource management in China. • Environmental impacts of both primary and secondary copper production are evaluated. • The ReCiPe model is applied to conduct this life cycle assessment. • Secondary copper production generates much less environmental impacts. • Various policies and measures should be taken to improve the overall copper resource efficiency. [ABSTRACT FROM AUTHOR]

The recycling of copper cables wastes has as main objective the recovery of copper. The effectiveness of this operation is guaranteed by the following factors: infrastructure able to collect, select and sort these wastes; a market capable to capitalize copper recovered from cables wastes to their true value; processors with equipment and technologies to achieve maximum recycling yields without negative effects on the environment. The most effective chains for wastes recycling may be considered those which use the copper recovered in wires and rods production. So is possible the design and operation of specialized flows for production of secondary copper with high purity. Contrary, a less efficient management of these wastes lead to the poor collection and mixed storage mixed with other types of copper scrap. In this case the copper wire can be recycled effectively to obtain copper-based alloys if special measures are applied at the recycling. The paper analyzes the driving forces that motivate the recycling of copper cables wastes. Also are presented the smelting experiments for obtaining high quality secondary copper and secondary brass from feed containing copper recovered from cables wastes into electric crucible furnace. The results are analyzed in terms of recovery yield and chemical composition. [ABSTRACT FROM AUTHOR]

Improving the service life of oxygen lance is a key assignment in electronic scrap smelting process. The degradation mechanism of 304, 310S, 316L, and 321 stainless steels in FeO x -SiO 2 -CaO-Al 2 O 3 slag were experimentally studied at the range of 1300–1400 °C, in the air and at p O2 = 10-7 atm. The oxidation and dissolution of steel components, and the formation of (Ni,Fe)(Fe,Cr,Al) 2 O 4 spinel phases caused steel degradation. The chrome oxide layers protected the stainless steel from further corrosion at high p O2. 310S stainless steel had the best performance in the experimental conditions, and 321 stainless steel was also stable at low temperatures. ● High-Al 2 O 3 containing slag in E-scrap smelting eroded oxygen lance seriously. ● Degradation mechanism of multiple stainless steel were experimentally studied. ● Alloy components oxidation and peeling off were major cause of materials wearing. ● The adding of Cr and Ni in stainless steel were beneficial against the slag corrosion. ● A dense reaction interface made by chrome oxide and spinel phases was positive. [ABSTRACT FROM AUTHOR]

Abstract: Secondary copper production has received much attention for its high emissions of polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) reported in previous studies. These studies focused on the estimation of total PCDD/F and polychlorinated biphenyl (PCB) emissions from secondary copper smelters. However, large variations in PCDD/F and PCB emissions reported in these studies were not analyzed and discussed further. In this study, stack gas samples at different smelting stages (feeding-fusion, oxidation and deoxidization) were collected from four plants to investigate variations in PCDD/F and PCB emissions and characteristics during the secondary copper smelting process. The results indicate that PCDD/F emissions occur mainly at the feeding-fusion stage and these emissions contribute to 54–88% of the total emissions from the secondary copper smelting process. The variation in feed material and operating conditions at different smelting stages leads to the variation in PCDD/F emissions during the secondary copper smelting process. The total PCDD/F and PCB discharge (stack gas emission+fly ash discharge) is consistent with the copper scrap content in the raw material in the secondary copper smelters investigated. On a production basis of 1ton copper, the total PCDD/F and dl-PCB discharge was 102, 24.8 and 5.88μgTEQt−1 for the three plants that contained 100%, 30% and 0% copper scrap in their raw material feed, respectively. [Copyright &y& Elsevier]

The subject of interest in this study was lead cementation with zinc from solution after conventional agitate acidic leaching of converter dust from secondary copper production. The kinetics of lead cementation from an acid solution of lead acetate using zinc powder was studied. The optimal cementation conditions for removing lead from the solution were determined to have a stirring intensity of 300 rpm, a zinc particle size distribution <0.125–0.4> mm and an ambient temperature. Under these conditions, an almost 90% efficiency in removing lead from solution was achieved. The cementation precipitate contains Pb, and a certain amount of Cu. Lead is present in the cementation precipitate in the PbO, Pb5O8 and Pb(Cu2O2) phases. The solution after cementation was also refined from copper. The solution can be used for further processing in order to obtain a marketable Zn-based product. The resulting cementation precipitate can be further processed and modified to obtain a lead-based product. A kinetic study of the process of lead cementation from solution was also carried out. Based on experimental measurements, the value of apparent activation energy (Ea) which was found to be ~18.66 kJ·mol−1, indicates that this process is diffusion controlled in the temperature range 293–333 K. [ABSTRACT FROM AUTHOR]

The application of Nerin Recycling Technologies (NRT) in electronic waste (E-waste) smelting was introduced in this study, and the material and energy balance was calculated based on the practical data with the METSIM software (METSIM International, USA). The main results are as follows: (1) the optimized processing parameters in the NRT smelting practice were the E-waste feeding rate of 5.95 t/h, oxidation smelting duration of 3.5 h, reduction smelting duration of 0.5 h, oxygen enrichment of 21–40 vol.%, oxygen consumption of 68.06 Nm3/ton raw material, slag temperature of 1280 °C, slag composition: Fe/SiO2 mass ratio of 0.8–1.4, CaO, 15–20 wt.%, Cu in crude copper ≥ 95 wt.%, Cu in slag, 0.5 wt.%, recovery of Cu, Au, and Ag ≥ 98%; (2) 98.49% Au, 98.04% Ag, 94.11% Ni, and 79.13% Sn entered the crude copper phase in the smelting process, 76.73% Pb and 67.22% Zn volatilized to the dust phase, and all halogen elements terminated in the dust and off-gas; (3) total heat input of the process was 79,480 MJ/h, the energy released by chemical reactions accounted for 69.94% of the total, and heat from fuels burning accounted for 33.04%. The energy brought away by the off-gas was 38,440 MJ/h, which was the largest part in heat output. The heat loss with the smelting slag accounted for 28.47% of the total. [ABSTRACT FROM AUTHOR]

The effects of fabric filters and desulfurization systems during secondary copper smelting on polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/Fs) concentrations, emission coefficients, and profiles were studied in an oxygen-rich smelting furnace and an anode furnace. In the anode furnace, the toxic equivalent (TEQ) concentration ranges were 0.106–1.04 ng World Health Organization (WHO)-TEQ/m3 at the fabric filters inlet and 0.027–0.17 ng WHO-TEQ/m3 at the outlet. For the oxygen-rich smelting furnace, the TEQ concentration ranges were 1.21–1.93 and 0.010–0.019 ng WHO-TEQ/m3 at the desulfurization system inlet and outlet, respectively. The TEQs in the outlet stack gases of the desulfurization system from the anode furnace were 0.0041–0.016 ng WHO-TEQ/m3. It is likely that PCDD/Fs that were taken away from the stack gases were adsorbed by the fly ash and gypsum. Solid residues were the dominant release routes for PCDD/Fs. PCDD/Fs congener and homologue profiles of stack gases from different smelting stages were similar. The contributions of more chlorinated homologues from the anode furnace decreased observably after the stack gases passed through the fabric filters. However, the desulfurization process did not greatly change the PCDD/Fs homologue profiles. Overall, both the fabric filters and desulfurization systems showed excellent removal efficiencies for PCDD/Fs in the stack gases, which reduced the TEQ emissions to well below the 0.5 ng WHO-TEQ/m3 to achieve standard discharge. Image 1 • Effects of fabric filters and desulfurization on PCDD/Fs reduction were studied. • Fabric filters and desulfurization had excellent removal efficiencies for PCDD/Fs. • PCDD/F emissions from oxygen-rich smelting furnace were higher than anode furnace. • The fly ash and gypsum have become new PCDD/F sources. • Removal efficiencies by desulfurization decreased as chlorination level increased. [ABSTRACT FROM AUTHOR]

In order to meet the massive demand of copper (annual consumption of 30–39 kg per person), Taiwan is faced with the decision: whether it makes sense to connect the arterial and venous industries by setting up a refinery that recovers and refines copper from the waste. This study aims to fill the research need to develop the methodology for evaluating the economic effects of incorporating the industrial chains for resource reuse and recycling. By constructing a secondary copper waste input–output (SeCuWIO) model that identifies the relationship between waste flows and the economic activities of the production (arterial) and waste treatment (venous) industry sectors, this study proposes a circular economy assessment tool from a macroeconomic perspective to assess the economic feasibility of closing the loop of a concerned material. The SeCuWIO model is used to estimate the changes in the unit production costs of various sectors after implementing a secondary copper resource recycling system. A scenario analysis shows that while most of the 52 industry sectors show variations within 1%, the pollution remediation sector exhibits a cost decrease of more than 2%. It is found that when a capacity with 60,000-ton electrolytic refinery and 6,000-ton leaching plant is installed, the total production cost in the economy to meet final demand for electrolytic copper amounts to 12,520 million NTD, which is higher than 12,510 million NTD of importing the same 53,280 tons at the present import price of 234,800 NTD/ton. Once the import price is above 234,980 NTD/ton, it will be beneficial from the resource and economic aspects to build such a domestic refinery plant that recovers and refines the copper from the waste. This study illustrates the diagnostic features of the SeCuWIO model and provides useful insights for waste and resource management regarding the industrial structure modification to promote circular economic structure. Image 1 • The secondary copper waste input output model is constructed. • The model is combined with a price vector. • Existing copper processing and future technologies are evaluated. • The model evaluates the economic effects of incorporating the recycling sectors. • The model assesses refinery scenarios for supporting circular economy strategies. [ABSTRACT FROM AUTHOR]