A physico-chemical separation process for upgrading iron from waste copper slag

• A separation process for upgrading iron from waste copper slag was developed.
• The process mainly includes reduction, crushing and magnetic separation steps.
• The magnetic product obtained from the process contains over 65 wt.% iron.
• The percentage recovery of iron in the process was over 85%.

A large amount of waste copper slag containing about 35–45 wt.% iron is generated every year from pyrometallurgical processes for producing copper from copper concentrate. Recovery of iron from the waste copper slag is of great interest for comprehensive use of mineral resource and reduction of environmental problems. In this study, a method for upgrading iron from the waste copper slag discharged as an industrial waste has been developed. The process first crushes the waste copper slag between 150 and 203 μm, followed by reduction reaction at 1250 °C for 1.5 h. And then, the resulting material is again crushed to 75–104 μm, followed by dry magnetic separation. Using the developed process, a magnetic product containing more than 65 wt.% iron was obtained from magnetic separation under a magnetic field strength of 0.03 T for the waste copper slag treated by reduction reaction. At the same conditions, the percentage recovery of iron was over 85%. It was also found that iron in the magnetic product mainly exists in iron metal, iron carbide, and iron oxides.