Fluorine Fixation During the Co-treatment of Spent Cathode Carbon and Copper Slag

Resource and harmless treatment of spent cathode carbon (SCC) in aluminum electrolysis and copper slag is a great significance in the environmental protection and sustainable development of resources. This study proposes to use SCC as a reductant for copper slag cleaning and CaO as an additive to recover copper from the slag while achieving fluorine fixation. After adding 2.4 pct CaO at 1220 degrees C, fluorine exists in the form of CaF2 in slag, and the fluorine fixation rate and copper recovery are 81.32 and 94.04 pct, respectively. When excessive CaO is added, the fluorine phase in the slag is transformed into Ca4Si2O7F2. The leaching toxicity of fluorine after co-treatment is 8 mg/L, which meets the national emission standard (100 mg/L). The co-treatment of SCC and copper slag improves the utilization of industrial waste and achieves harmless treatment of hazardous waste. [GRAPHICS] . (c) The Minerals, Metals & Materials Society and ASM International 2023