Iron recovery from lead smelting water-quenching slag by “roasting–grinding–magnetic separation” method

This study explored the recovery of valuable metal elements in the lead smelting water-quenching slag using the method of “roasting–grinding–magnetic separation” at a roasting temperature of 1250 °C, coal dosage of 12.5%, roasting time of 90 min, and grinding time of 45 min. An iron concentrate with a grade of 93.61% and a recovery rate of 90.71% were obtained. The mechanism shows that iron-containing minerals undergo a reduction reaction with the increase in temperature. The iron in the water-quenching slag before roasting exists in the form of magnetite, but it is difficult to dissociate due to the fine particles. Conversely, the iron in the burned slag after roasting exists in the form of dissociated metallic iron, and it can be recovered better via grinding and magnetic separation. This study provides new theoretical guidance for effective recycling and utilization of resources. [Display omitted] •Achieve recovery of difficult-to-dissociate high-content magnetite from lead slag.•Rising temperatures speed up particle nucleation to form recyclable metallic iron.•Integrate roasting and magnetic separation, open up a new way of resource recovery.•Refining and providing innovative theoretical guidance through modern test methods.