The mechanism of ilmenite leaching during experimental alteration in HCl-solution

Ilmenite (FeTiO3) is an important mineral being the raw material for the production of titanium for the high-tech industries. The production process typically involves acid treatment, which oxidises and removes the Fe, leaving a TiO2-rich phase, generally rutile. In naturally weathered ilmenite, Grey and Reid (1975) first proposed a two-stage alteration mechanism and remains the generally accepted model [1]. In the first stage ilmenite undergoes weathering through oxidation and removal of Fe to form an apparently continuous series of compositions from ilmenite to pseudorutile (ideally Fe2Ti3O9). The Fe is assumed to diffuse out through the unaltered oxygen lattice. Pseudorutile is a transitional phase and undergoes incongruent dissolution to form rutile, hematite and goethite [2].