Effect of Vacancy, As, and Sb Dopants on the Gold-Capturing Ability of Cu2S during Gold Collection in Matte Processes

The technique of gold collection in matte can effectively improve the trapping efficiency of precious metals such as gold, silver, and platinum. However, the underlying mechanism of gold collection from high-temperature molten matte is complex and not well understood. In this work, the first-principle calculations were utilized to investigate the adsorption behavior of gold atoms on a Cu2S surface. The effects of vacancies and As and Sb doping on the gold-trapping ability of Cu2S were also explored, and the electronic properties of each adsorption system, including the charge density difference, density of states, and charge transfer, were systematically analyzed. The results show that the Cu-terminated Cu2S(111) surface has the lowest surface energy, and the Au atom is chemically adsorbed on the Cu2S(111) with an adsorption energy of -1.99 eV. The large adsorption strength is primarily ascribed to the strong hybridizations between Au-5d and Cu-3d orbitals. Additionally, the Cu vacancy can significantly weaken the adsorption strength of Cu2S(111) towards Au atoms, while the S vacancy can notably enhance it. Moreover, due to the formation of strong covalent As-Au/Sb-Au bonds, doping As and Sb into Cu2S(111) can enhance the gold-trapping capability of Cu2S, and the Sb doping exhibits superior effectiveness. Our studied results can provide theoretical guidance for improving the gold collection efficiency of Cu2S.