The Dissolution of Titanium Minerals in Hydrochloric and Sulfuric Acids

Abstract

Abstract Kinetic dissolution experiments of powdered ilmenite and rutile were carried out in sulfuric and hydrochloric acids (0.03–1 M) at temperatures of 40, 65, and 90 °C in order to study the physico-chemical factors and the mechanism for the leaching of titanium and iron from these minerals and rocks under acidic conditions. The dissolution rate of ilmenite was strongly affected by the acidity and temperature of the acid solutions; the rate changes in the H2SO4 solutions were greater than those in the HCl solutions. The dissolution rate of rutile was much slower than that of ilmenite. Ilmenite was decomposed by the dissolution of titanium and iron in a nearly stoichiometric ratio under strongly acidic conditions such as 0.3–1 M. But under milder conditions, such as 0.03–0.1 M at 90 °C, the dissolution rate of titanium dropped rapidly in the initial step and the curved line for iron dissolution was nearly parabolic, suggesting the diffusion of iron through the residual layer of titanium.