New insights on scandium separation from scandium concentrate with titanium dioxide wastewater

In this study, a scandium concentrate with Sc2O3 content of 66.24 g/t was obtained from V-Ti magnetite tailings by physical concentration, and the main Sc-bearing minerals were augite and hornblende. A novel process of roasting and leaching was proposed to extract scandium from scandium concentrate with titanium dioxide wastewater. Scandium concentrate was pretreated by roasting, and titanium dioxide wastewater was used to directly leach scandium from the roasted ore. The effects of roasting and leaching parameters such as roasting temperature, roasting time, roasting agents, leaching temperature, leaching time, liquid-to-solid ratio, and leaching agents on scandium separation were thoroughly researched in the experimental procedure. The results show that a scandium leaching efficiency of 85.89% was obtained, and the scandium content of leaching residue decreased to 9.31 g/t under the optimal conditions: a roasting temperature of 1123 K, a roasting time of 120 min, a leaching temperature of 343 K, a leaching time of 120 min, and a m (titanium dioxide wastewater)∶m (roasted ore)∶m (ammonium fluoride) ratio of 8∶1∶0.09. The main findings of the scandium separation mechanism show that Sc-bearing minerals can effectively decompose and release scandium element after roasting, and created favorable conditions for scandium leaching with titanium dioxide wastewater to achieve the purpose of scandium recovery.