Separation and recovery of scandium and titanium from spent sulfuric acid solution from the titanium dioxide production process

The separation and recovery of scandium and titanium from hydrolyzed sulfuric acid solution of titanium dioxide production using solvent extraction was investigated. A mixed solution of Na3PO4 and H2O2 was used to selectively scrub titanium from the loaded organic solution containing scandium and titanium. The results showed that the scrubbing of titanium reached 95% with mole ratios nP/nTi of 2/1 and nH2O2/nTi of 3/1 at an O/A of 1/1 and 50 °C for 15 min in a single stage, and further reached > 98% through a three-stage counter current scrubbing with mole ratios nP/nTi of 1.5/1 and nH2O2/nTi of 2/1 at an O/A of 1/1 and 25 °C for 15 min. The co-scrubbed scandium was < 4%. Compared with the traditional methods of H2SO4/H2O2 scrubbing, the new system of Na3PO4 and H2O2 exhibited significant advantages of higher scrubbing of titanium and lower loss of scandium.