Research progress on the separation of iron and silicon from copper slag

Copper slag is the main solid waste generated during copper production by pyrometallurgical method. Its stockpile not only occupies a lot of land but also pollutes the surrounding water and soil. One of the main research directions for the resource utilization of copper slag is iron extraction since the Fe content is as high as 35%~40%. In copper slag, Fe and SiO₂ are the main chemical compositions, and the main minerals are fayalite and magnetite. Thus the core issue for selectively extracting iron from copper slag is the efficient separation between iron and silicon. The current methods of separating iron and silicon from copper slag were reviewed in this paper, such as magnetic separation, smelting reduction, selective oxidation-magnetic separation, carbothermal reduction-magnetic separation, oxidation roasting-alkaline leaching and carbothermal reduction-alkaline leaching. Furthermore, their principles, research status and existing problems were also analyzed and discussed. The results showed that the sole recovery of iron from copper slag generated large amounts of secondary tailing or slag, but the comprehensive recovery of iron and silicon was the key to obtaining clean copper slag with high-value utilization.