A study on the recovery of titanium from hydrofluoric acid leach solution of ilmenite sand

Abstract

Pigment grade titanium dioxide (99.9% (wt.) TiO 2 and 0.004% (wt.) Fe) was recovered from the hydrofluoric acid leach solution of ilmenite using the following steps: (1) precipitating out the Ti and Fe compounds from fluoride leach solution using sodium hydroxide solution; (2) oxidising Fe(II) to Fe(III) using HNO 3 acid; (3) dissolving the solid mass in 7.5 M HCl; (4) extracting most of the Fe(III) by a two-stage methylisobutylketone (MIBK) extraction; (5) adjusting the pH of the aqueous phase to zero in order to extract titanium with di-2-ethylhexylphosphoric acid (D2EHPA) and leave siliceous materials in the aqueous phase; (6) stripping the organic phase with 0.5 M Na 2 CO 3 solution to get a quantitative precipitation of metatitanic acid; and (7) filtration of the aqueous suspension of metatitanic acid, oven-drying and finally ignition at 1000°C. The overall recovery yield of TiO 2 from the leach solution was greater than 92.5% (wt.). The MIBK, HCl and D2EHPA could be recovered and recycled.