| abstract |
Titanium dioxide is recovered from ilmenite in high purity and high yield. The ore is leached with concentrated hydrochloric acid at room temperature to dissolve at least 80% of the titanium and iron values of the ore and to leave gangue material substantially undissolved. After separation from solid gangue material and conversion of ferric iron to ferrous iron, the titanium chlorides are hydrolyzed and titanium oxyhydrate is precipitated. A substantial proportion of the ferrous chloride may be removed from the solution by crystallization prior to the hydrolysis of the titanium chlorides. The titanium oxyhydrate, after separation from the mother liquor, and purified, if necessary to remove traces of ferric materials, is dried and converted into substantially pure pigment grade titanium dioxide. The iron values may be recovered from the mother liquor and a closed hydrochloric acid cycle may be established. |