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

• Published in: Hydrometallurgy 2016-12, Vol.166, p.73-79
• Main Authors: Arachchi, N.D.H., Peiris, G.S., Shimomura, M., Jayaweera, P.M.
• Format: Article
• Language: English
• Subjects: Acid leaching; Decomposition; Ilmenite; Leaching; Roasting; Sand; XPS; XRD; Zinc oxide; Zinc sulfides; ZnO/ZnS
• ISSN: 0304-386X; 1879-1158
• DOI: 10.1016/j.hydromet.2016.09.001

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 5.0M HCl at 30°C and 6.0M 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. •Roasting ilmenite with ZnO/ZnS enhances the acid leaching.•Used ZnO is recoverable and act as a catalyst for the proposed process.•ZnS deposits such as sphalerite is a possible raw material.