Abstract
The distributions of Ga, In, Sn, and Te between copper-iron mattes and silica-saturated iron silicate slags over a wide range of matte grades 55 to 75 pct Cu were determined at 1300 °C using a gas-phase equilibration-quenching technique and direct phase composition analysis by Electron Probe X-ray Microanalysis and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry. Alumina from aluminum, a typical minor element of electric and electronic copper scrap, and lime were adopted as slag modifiers for increasing the trace element recoveries. Gallium and tin were distributed predominantly in the slag, indium preferred sulfide matte at low matte grades and slag at high, whereas tellurium strongly favored the sulfide matte in particular in high matte grades. The slag modifiers alumina and lime had a minor impact on the distribution coefficients of gallium and tin, but for indium and tellurium the distribution coefficients were more strongly affected by the basic oxides. The strong tendencies of tin and tellurium to vaporize at the experimental temperature were confirmed.
Highlights
DEMAND of many critical metals has increased significantly over the last decades[1] and the supply has been complied mostly from primary sources, whereas their recycling is a minor factor.[2]
The present results show a good agreement with the recent data of Fallah-Mehrjardi et al.[32] and indicate a clear impact of lower smelting temperature on the chemical solubility of copper in the slag
The tin distribution data by Koike and Yazawa[21] at 1250 °C and silica saturation are in good agreement with the present results
Summary
DEMAND of many critical metals has increased significantly over the last decades[1] and the supply has been complied mostly from primary sources, whereas their recycling is a minor factor.[2] Their fundamental properties in silicate slags and sulfide mattes are scarce. Selected experimental data on the chemistry of the trace elements of this study, Ge, In, Sn, and Te, are available in the geochemical literature. Capobianco et al.[3] studied the distributions of gallium and tin between silicate melts and iron-nickel alloys in reducing conditions and found them to dissolve as GaO1.5 and SnO in silicate melts at 1260 °C. Brenan[4] studied the distribution of tellurium between molten and solid sulfides and silicates.
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