Decomposition of ilmenite by ZnO/ZnS: Enhanced leaching in acid solutions

Acid leaching of ilmenite (FeTiO3) obtained from beach sand was found to be more effective when roasted with ZnO or ZnS at 900 °C. Remarkably higher iron and titanium leaching rates were observed when compared with normal ilmenite in 5.0 M HCl at 30 °C and 6.0 M H2SO4 at 110 °C, respectively. Roasting of ilmenite with ZnO or ZnS converts acid resistant FeTiO3 to more reactive Fe2O3 and Zn2TiO4, resulting in enhanced leaching. Roasting FeTiO3 with ZnS generates SO2 as a byproduct, which can be used to produce H2SO4 acid required in the sulfate process. Added ZnO or ZnS can be recovered as ZnO, therefore the overall process acts as a catalytic decomposition of FeTiO3. Ores containing ZnS, such as sphalerite, are possible raw materials instead of ZnS, in a commercial application. XRD analysis confirms the formation of zinc titanate, and XPS results indicate the presence of both Fe2 +/Fe3 + in naturally weathered ilmenite.