Waste control by waste: Recovering iron from red mud with the effect of Phosphogypsum-included additive

Red mud (RM) and phosphogypsum (PG) are both large-scale industrial solid wastes, which cause waste of resources reserved in them and pose a huge threat to the environment if not treated appropriately. Guide by the concept of “waste control by waste”, the individual and cooperated effect of PG and sodium sulfate (Na 2 SO 4 ) on iron recovering from RM through reductive roasting-magnetic separation process was comparably investigated. Systematical factorial tests verified the advantage of binary additive. An iron concentrate with iron grade and recovery of 89.02 % and 87.46 % was obtained under the optimized conditions. Mechanistic studies demonstrated that iron oxides were converted to metallic iron through reductive roasting, along with which PG was beneficial for the releasing of iron from complex iron-hosting minerals to a certain extent while binary additive was even more efficient for the reducing, decomposing and grain growing processes. This work realizes the simultaneous utilization of both waste resources.