With the aim of investigating deportments of precious metals in pyrometallurgical processing of waste electrical and electronic equipment, the distributions of selected precious metals (gold, silver, platinum, and palladium) between copper matte and three different silica-saturated slags (pure FeO _x -SiO₂, FeO _x -SiO₂-Al₂O₃, and FeO _x -SiO₂-Al₂O₃-CaO slag) were investigated at 1300 °C in controlled flowing CO-CO₂-SO₂-Ar gas atmosphere by a high-temperature isothermal equilibration technique. The phase compositions were analyzed by Electron Probe X-ray Microanalysis and Laser Ablation-High Resolution Inductively Coupled Plasma-Mass Spectrometry. It was shown that the distribution coefficients of gold, platinum, and palladium between matte and slag (L ^m/s(Me) = [Me]_{in matte}/(Me)_{in slag}) were very high and increased with increasing matte grade. The distributions to the matte phase were increased by adding basic oxides alumina and lime into the acidic silicate slags. The experimentally measured distribution coefficients L ^m/s(Me) followed the order of platinum > palladium > gold > silver. The present experimental results can be used for upgrading thermodynamic databases for the complex recycling processes through nonferrous smelting.

Different types of metal-bearing wastes, such as WEEE (Waste Electrical and Electronic Equipment), are important urban minerals in modern society, and the efficient recycling and reuse of their metal values is of key interest. Pyrometallurgical copper smelting is one of the most prominent ways of treating WEEE, however, more accurate experimental data is needed regarding the behavior of different elements during each process stage. This article investigates the behavior of tin and antimony, both commonly present as trace elements in electrical and electronic waste, in secondary (i.e., sulfur-free) copper smelting conditions. The experiments were conducted in oxygen partial pressure range of 10⁻¹⁰–10⁻⁵ atm, covering the different process steps in copper smelting. The basis of the equilibrium system was metallic copper–iron silicate slag, with the addition of alumina and potassium oxide to account for the presence of these compounds in the actual industrial process. The results showed that the distribution coefficients of both trace metals, L^Cu/slag = [wt % Me]_copper/(wt % Me)_slag, increased significantly as a function of decreasing oxygen pressure, and the addition of basic potassium oxide also had an increasing effect on the distribution coefficient. A brief comparison between EPMA and LA-ICP-MS (electron probe microanalysis and laser ablation–inductively coupled plasma–mass spectrometry), the two in situ analytical techniques used, was also presented and discussed.

The distribution coefficients of Ni, Co, Ag, Au, Pt, and Pd between molten copper and silica-saturated iron silicate slags ( $$ {\text{L}}_{\text{Me}}^{{{\text{Cu}}/{\text{s}}}} $$ L Me Cu / s ) 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 10⁻⁸ to 10⁻⁴ 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 coefficients $$ {\text{L}}_{\text{Me}}^{{{\text{Cu}}/{\text{s}}}} $$ L Me Cu / s determined can be arranged in the following order: Pt > Au > Pd >> Ag > (Cu) > Ni > Co > (Fe).

Waste electrical and electronic equipment (WEEE) represents a significant urban resource for precious metals. To maximize the recoveries and sustainable use of these metals, their behavior needs to be characterized in the secondary copper smelting of WEEE. The current study experimentally determined the distributions of gold, silver, platinum and palladium between copper alloy and FeO_x–SiO₂–Al₂O₃/FeO_x–SiO₂–Al₂O₃–CaO slags (L^Cu/s[M] = [M]_Copper/[M]_Slag) over the oxygen partial pressure range of 10⁻⁵ – 10⁻¹⁰ atm at 1300 °C. In addition, the equilibria of copper alloy, slag and Al–Fe spinel system are presented and discussed. The experiments were conducted employing an equilibration—drop-quenching technique followed by major element analysis with Electron Probe MicroAnalysis (EPMA) and trace element analysis with sensitive Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The results showed that the distribution coefficient of silver increased from 10 to 10³ as a function of decreasing oxygen partial pressure. For gold, platinum and palladium, the distribution coefficients were at minimum 10⁵. Lime addition improved the recovery of silver notably and had a small positive effect on gold recovery into copper. Overall, the precious metals can be recovered very efficiently in copper alloy via secondary copper smelting with alumina-rich iron-silicate slags.