A Novel Strategy for the Simultaneous Recovery of Silicon and Copper from Spent Silicon Contact Mass

The recovery of silicon and copper from spent silicon contact mass (SSCM) holds significant importance for environmental protection and resource scarcity. This study introduced a novel strategy that combines low-temperature and oxygen-poor roasting, and selective leaching, exhibiting high efficiency in recovering Si and Cu in the form of Si–Cu powder from SSCM. The recovered Si–Cu powder can be used as high-quality raw materials for Si–Cu composite materials, and is expected to continue to be used as monomer production raw materials. A protective Si oxide layer on the outer surface, formed during the low-temperature and oxygen-poor roasting process, preventing the undesirable oxidation of Si powder, and the C in the SSCM was effectively removed. The chemical stability difference between Cu and other metallic elements was exploited during selective leaching with mixed HCl–HF acid, resulting in the targeted removal of impurities. The thermodynamics of impurity leaching was analyzed by E-pH diagram, and the kinetic behavior of impurity leaching was described elucidated using homogeneous model. This innovative strategy marks the first instance of combining C removal with selective leaching of metallic impurities, achieving efficient and functional utilization of SSCM. This study offered a new and effective approach to SSCM treatment.