A Novel Synergetic Process for Scandium Separation from Scandium Concentrate with Titanium Dioxide Wastewater

Abstract

An effective process was proposed to extract scandium from a scandiumconcentrate with Sc2O3 content of 0.006624% and titanium dioxide wastewater with Sc content of 3.661 mg/L. After roasting and modified pretreatment of scandium Concentrate, the free acid in titanium dioxide wastewater is used as a leaching agent for the co-leaching of scandium. The result shows that: under the conditions of salt-free roasting, the roasting temperature of 850℃, roasting time of 2.0 h, leaching temperature of 80℃, leaching time of 2.0 h, leaching liquid-solid ratio of 8, leaching additive of NH4F and leaching additive consumption of 12%, the leaching results are optimal. A leaching efficiency of 83.90% can be reached. Meanwhile, the scandium content of the leaching residue decreases to 0.00115%. The SEM-EDS, XRD and Thermogravimetric analyses of scandium Concentrate, roasted ore and leaching residue show that: There will be two weight-loss phenomena during the roasting process. After roasting and modification, pyroxene and feldspar minerals can effectively decompose and release scandium element. It would create favourable conditions for the leaching of scandium with titanium dioxide wastewater and accomplish the purpose of synergic strengthening leaching and separation of scandium.