Liberation and Enrichment of Metallic Iron from Reductively Roasted Copper Slag

Iron recovery from copper slag generated during copper production by the pyrometallurgical method has been widely investigated to achieve resource utilization. Liberation and enrichment of metallic iron from reductively roasted copper slag were explored in this work. Results show that metallic iron, quartz solid solution, and cristobalite solid solution are the main phases in reductively roasted copper slag, and most metallic iron particles are wrapped by silica. A concentrate with 74.39% Fe content and 83.14% Fe recovery is obtained through grinding–magnetic separation. For comparison, the metallic iron particles are liberated through alkali leaching of silica. The Fe content in leaching residue reaches 78.17% by removing 88.96% SiO2 and further increases to 90.45% by magnetic separation with Fe recovery of 85.20%. Therefore, alkali leaching–magnetic separation is suitable for treating reductively roasted copper slag because of the high Fe content in concentrate and comprehensive recovery of silica.