Synergetic Treatment of BOF Slag and Copper Slag via Oxidation–Magnetic Separation for MgFe2O4 Preparation and Non-Magnetic Slag Stabilization

This study proposes a synergistic treatment method for BOF slag and copper slag via oxidation–magnetic separation, with the dual goals of preparing MgFe2O4 magnetic material and stabilizing the non-magnetic slag. The effects of copper slag addition, the oxidation temperature and the oxidation time on the phase transformation and MgFe2O4 morphology during the oxidation process are investigated. The results show that copper slag addition can release the simple iron oxides of FeO and Fe2O3 from iron-containing phases from BOF slag and copper slag, promoting the synthesis of MgFe2O4. Furthermore, the oxidation temperature and oxidation time have a significant influence on the size of the MgFe2O4 particles. To obtain the MgFe2O4 magnetic material, the optimum oxidation parameters were used, with an oxidation degree of Fe2+ of 95.85% and a yield of MgFe2O4 of 90.31%. In addition, the main phase of non-magnetic slag was Ca2SiO4, and both free CaO and free MgO from BOF slag were eliminated, indicating a potential application in construction materials. This technology maximizes resource utilization and the valorization of metallurgical solid waste.