Improving Separation Of Cu Fe From Copper Slag By Modifying The Copper Slag

In China, iron and copper resources are very scarce, the degree of dependence upon imported ore reaches up to60-85%, but the copper slag contains a lot of valuable metals, including iron content of about40%and copper content of1%, which are not effectively used. As iron in the copper slag mainly exists in the magnetite and olivine, and copper is primarily dispersed in the slag in the form of fine matte particles, both the useful minerals and gangue minerals are closely disseminated, which is difficult to recover the copper and iron in the slag by conventional separation techniques, and lots of latent heat is underutilized when discharging the slag. In this paper, copper slag was researched, and carried out study on high temperature modification-copper flotation-magnetic separation (or direct reduction-magnetic separation) process and mechanism, which had important practical significance.The copper flotation-iron magnetic separation studies showed that the recovery of iron was only33%in the magnetic separation process, while in the direct reduction-magnetic separation process, the direct reduced iron degree was only85.80%and the iron recovery was79.54%. The silicon content was too high that couldn’t meet the requirements of the electric furnace steelmaking.The high temperature modification of the slag copper flotation magnetic separation research showed that:modified the slag under the conditions of alkalinity0.45, compound additives12%, slag temperature1350℃, holding time120min, cooling rate1.5℃/min, cooling end-point temperature900℃and cooled it slowly. Then treated the modified slag by flotation and magnetic separation with the conditions of grinding fineness of-0.045mm90.2%, dosage of butyl xanthate200g/t, dosage of inhibitors3.6kg/t, flotation time5min, magnetic field intensity0.17T, we got better indicators that the crude copper concentrate degree was11.04%, copper recovery was71.45%, magnetic iron concentrate degree was56.31%and iron recovery was63.26%. Flotation tailings direct reduction-magnetic separation process showed that:in the conditions of reduction temperature1150℃, reduction time90min, coal-mass ratio2:1, the grinding fineness of-0.074mm94.33%, magnetic field intensity0.08T, we obtained direct reduced iron with iron degree of88.89%, iron recovery of88.72%. After melt modification, the iron recovery of copper slag was improved; reduced direct reduction temperature, direct reduced iron degree and iron recovery were increased3.09%and9.18%, respectively.The mechanistic studies of copper slag melt modification suggested that:the combination of alkalinity and additives could not only destruct fayalite effectively and promote iron transforming into magnetite, but also promote the sulfide, aggregation, development and growth of copper matte; suitable cooling rate was a requirement for magnetite and copper to grow up. Grain size coarsening of magnetite and copper matte was beneficial to the monomer dissociation in milling, which could improve the separation effect of copper-iron and the iron selection indicators.