Optimization of Alkaline Roasting to Enable Acid Leaching of Titanium from Anatase Ores

About 95% of titanium ore is processed to obtain pigment-grade titanium dioxide. The main titanium-bearing minerals used for this purpose are ilmenite (FeTiO 3 ) and rutile (TiO 2 ). Anatase, a low-temperature polymorph of rutile, is currently not used as a raw material for this purpose due to its l...

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Bibliographic Details
Published in:Journal of sustainable metallurgy 2023-03, Vol.9 (1), p.183-193
Main Authors: de Oliveira, A. L. B., da Silva, G. D. S., de Aguiar, P. F., Neumann, R., Neto, A. Alcover, Carneiro, M. C., Afonso, J. C.
Format: Article
Language:English
Subjects:
Acid leaching
Anatase
Earth and Environmental Science
Environment
Ilmenite
Low temperature
Metallic Materials
Optimization
Raw materials
Research Article
Roasting
Rutile
Sodium hydroxide
Sodium titanate
Solid phases
Sustainable Development
Titanium
Titanium dioxide
Titanium ores
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Summary:About 95% of titanium ore is processed to obtain pigment-grade titanium dioxide. The main titanium-bearing minerals used for this purpose are ilmenite (FeTiO 3 ) and rutile (TiO 2 ). Anatase, a low-temperature polymorph of rutile, is currently not used as a raw material for this purpose due to its large amount of impurities, making it unsuitable for conventional chloride and sulfate routes. In this work, an alkaline roasting procedure followed by acid leaching of a run of mine ore from a Brazilian anatase deposit was developed to enable titanium extraction. A Doehlert design was carried out to study the sample roasting with solid NaOH. The variables studied were roasting time, roasting temperature, and NaOH/ore mass ratio. After washing the roasted ore with water, the solid phase was leached using a 5 mol L −1 HCl solution. It was possible to leach over 97 wt% of titanium present in the sample, thus suggesting that the proposed method is effective and may be useful to recover titanium from anatase ores. XRD analyses of roasted samples were performed to elucidate the roasting reactions and titanium leaching efficiencies. Titanium suboxide (TiO 0.48 ) was proposed to be formed instead of sodium titanate when the roasting temperature was ≤ 450 °C. This result suggested that sodium titanate was not the only titanium leachable phase that can be formed during NaOH roasting of anatase ores. Graphical Abstract
ISSN:2199-3823
2199-3831
DOI:10.1007/s40831-022-00637-2