Abstract:
The CSIR-Ti process employs lithiothermic reduction of titanium tetrachloride feedstock to produce
titanium sponge. The product is therefore contaminated by a range of lithium and chloride species. In
this study we examine the effects of particle size, temperature, and HCl concentration as input leaching
variables on the removal of chlorides from the crude titanium sponge. A review of the aqueous chloride
chemistry of Li and Ti provided initial conditions for leaching of impurity species from the sponge.
Experimental results confirm that the effectiveness of leaching and removal of dissolved impurities
from the sponge are dependent on leaching kinetics, which are influenced by temperature, particle
size, and morphology. Of the variables tested, reaction temperature had the strongest influence on the
oxygen content of the leached product. The HCl lixiviant concentration had a negligible effect under the
conditions tested. Leaching of crude titanium sponge (−10 mm size fraction after crushing) at 14°C in
either 1 M or 0.032 M HCl yielded a titanium sponge product that met the ASTM standard specification
for commercially pure Grade 1 titanium, i.e., oxygen content < 0.18 mass% and chloride content < 0.15
mass%.
