China Nonferrous Metallurgy

As a by-product from copper smelting, copper slag is a kind of important secondary mineral resources. The copper slag contains Fe, Cu and a small amount of Zn, Co, Ni and other valuable metallic elements. Analysis is made for the occurrence and forms of the major valuable elements in the copper slag, and the current research status of the recycling technologies for major elements is reviewed. The analysis shows that the Fe element in copper slag is recycled mainly by the preliminary processing of the two forms of oxidizing-roasting enrichment of Fe3O4 or reducing-roasting enrichment of iron metal, and by magnetic separation or smelting-separation and other technologies; the mineral processing method and electric furnace cleaning method are the major routes to recycle Cu element in copper smelting slag; the use of rotary kiln or rotary hearth furnace process can realize the collaborative recycling of Fe and Zn in the copper slag. By using the hydrometallurgical leaching process, the Fe, Cu and Zn elements in the copper slag can be recovered in steps or collaboratively, but this technology has long process flow and a certain environmental pollution. A prospect about the potential technologies or methods for recycling valuable elements in copper slag is made and it is pointed out that utilizing the waste heat of molten copper slag to develop new high-temperature modifiers and new reducing agents (biomass carbon-containing reducing agent, secondary metal siliceous thermal reducing agent, etc.) presents a new direction for the study on the recycling technology of valuable elements in copper slag, which can realize energy-saving and consumption reduction in copper slag recycling as well as the collaborative recycling of other secondary resources.