Distribution of Ni, Co, Precious, and Platinum Group Metals in Copper Making Process
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The distribution coefficients of Ni, Co, Ag, Au, Pt, and Pd between molten copper and Cu=s silica-saturated iron silicate slags (LMe ) were measured experimentally. The distribution behaviors were studied under typical conditions of copper converting and fire refining, i.e., from 1250 °C to 1350 °C, and from 108 to 104 atm oxygen partial pressure. The coefficients were determined as the ratios of the trace element weight concentrations measured in situ, directly from the equilibrated metal and slag phases. For the quantitative elemental analysis of the phases, state-of-the-art analytic techniques, including electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry, were employed. The distribution Cu=s coefficients LMe determined can be arranged in the following order: Pt > Au > Pd >> Ag > (Cu) > Ni > Co > (Fe). https://doi.org/10.1007/s11663-019-01576-2 Ó The Author(s) 2019
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INTRODUCTION
OUR society requires a continuous, ever-increasing supply of metals to maintain modern levels of living. Growing metal demand with decreasing natural resources requires dramatic increases in metal recycling, achievable only with the ability to process new complex feed materials efficiently. For metals’ production from these complex materials, accurate thermodynamic and phase equilibrium data are essential, especially for the minor elements in the base metals processing. Sustainability and resource efficiency concepts are driving to develop integrated, cleaner processes, which fully utilize renewable resources, i.e., metals recycling, with the least environmental impact. In particular, the aim is to build an industrial circular economy model, which is ‘‘a regenerative system in which resource input and waste, emission, and energy leakage are minimized by slowing, closing, and narrowing material and energy loops’’.[1] Metal wastes, such as various end-of-life (EoL) electrical and electronic equipment, have a particularly high value as secondary sources of metals. The concentrations of valuable elements in e-wastes (WEEE) are
higher than in sulfidic copper ores.[2] The best practices for processing copper-bearing wastes and e-scrap worldwide are the black copper smelting route[3,4] and the primary matte smelting copper making route, integrated with secondary raw materials utilization.[5] A fraction of such wastes is processed through the black copper smelting route, where low-grade scrap is typically treated in top-submerged lance[6,7] and Kaldo furnaces under consecutive reducing and oxidizing conditions.[2] Alternatively, high-grade copper scrap can be charged directly to copper converter in the primary copper making route. Efficient processing of complex copper sulfide concentrates and scrap requires thermodynamic data for the separation of impurities under the copper-making conditions. Present industrial practices, especially for secondary materials processing, are not optimized. One of the main reasons is the scarcity of the available thermodynamic data for minor elements. Moreover, the elements of e-s
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