Eco-friendly iron extraction from fe-containing copper smelting slag via reduction roasting with coal and magnetic separation: Experimental and mechanism insights

Copper smelting slag (CSS) is a byproduct produced during the thermal smelting of copper and poses a considerable environmental challenge, particularly in China, where its accumulated volume surpasses 1.8 billion tons. This study utilized the response surface method (RSM) to optimize experimental procedures and reduce costs, the results showed that the effects of each factor on iron recovery were in the following order: roasting temperature > roasting time > coke dosage. The optimized iron recovery of iron extraction from CSS by Magnetization-roasting reached 78.87 %, while the actual iron recovery was 78.84 %. The relative error is very small, indicating that the model is effective. Conducted the thermodynamic computational analysis to understand the migration of metal phases in CSS, employed XPS analysis to identify valence changes in key elements, and the clever combination of restricted reduction kinetics and SEM-EDS analysis shows that the reduction reaction of CSS is mainly controlled by interfacial chemistry and carbon gasification at low temperatures. By processing CSS, the study successfully produced environmentally friendly iron that can be recycled, offering a sustainable solution for managing toxic waste from copper production.