The Removal of Titanium from Metallurgical Silicon by HF–HCL Leaching

The removal of titanium from metallurgical grade silicon (MG-Si) by HF–HCl leaching was investigated as a function of leaching time, temperature, particle size, and acid concentration. It was found that the extraction of titanium from MG-Si increased with a decrease in particle size and increase in hydrofluoric acid concentration. Titanium removal was improved very little by increasing temperature and hydrochloric acid concentration. The removal of titanium by HF–HCl took place rapidly. It was possible to remove 97% of the Ti after 0.5 h of leaching. A maximum of 99% of the Ti was removed by leaching MG-Si with 3% hydrofluoric acid and 2% hydrochloric acid at room temperature for 5 h. The main titanium-bearing Intermetallic compound in MG-Si is FeTiSi2, which cannot be attacked by hydrochloric acid but can be activated by it. Titanium is more easily removed from FeTiSi2 by hydrofluoric acid if this phase is first activated by hydrochloric acid.