Thermodynamics of Gallium (Ga) at Black Copper Smelting Conditions Relevant to E-Waste Processing

Electronic waste (E-waste) is considered as a hazardous material, however, it also contains valuable elements, including gallium (Ga). E-waste can be processed through the black copper smelting to recover these valuable elements. However, the detailed thermodynamics behavior of many of the valuable elements during black copper smelting has not been studied comprehensively. This study aims to investigate the thermodynamics of Ga in copper and slag at black copper smelting conditions. High-temperature equilibrium experiments were carried out to measure the distribution ratio of Ga in Fe2O3–CaO–SiO2 slag and copper at temperature range of 1300 °C to 1450 °C (1573 K to 1723 K) and partial pressure of oxygen (pO2) of 10–6 to 10–11 atm. The effect of FeT/SiO2 ratio and basicity (measured as CaO/SiO2) of the slag on the distribution ratio of Ga were also investigated. The partitioning of Ga into the copper phase was found to increase with decreasing oxygen partial pressure, and with increasing temperature, FeT/SiO2 ratio and basicity. The study revealed that a basic slag at higher temperature and at a reducing atmosphere was favorable to increase Ga partitioning to the copper.