Co-modification of BOF Slag and Copper Slag to Recover Valuable Metals by Carbothermal Reduction

A novel co-modification method between BOF slag and copper slag is proposed for the effective recovery of valuable metals in the metallurgical slags. The co-modification reactions between the Ca-containing phases in BOF slag and fayalite in copper slag are discussed on the basis of thermodynamic analysis, and the co-modification effect on the phase reconstruction and separation of iron oxides from Ca-containing and Si-containing complex compounds in the co-modified slag are investigated by a laboratory experiment. The effects of carbothermal reduction conditions, including the basicity of co-modified slag, reduction temperature, and C/O molar ratio, on the metal recovery rate are evaluated and optimized. The results under optimal process conditions show that it is possible to extract metals in the co-modified slag as Fe-Cu-Mn alloy with a lower P content, and to realize the stabilization of the secondary slag without free lime and periclase.