|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Applications of Process Engineering Principles in Materials Processing, Energy and Environmental Technologies: An EPD Symposium in Honor of Professor Ramana G. Reddy
||An Investigation on the Kinetics and Mechanism of Alkali Reduction of Mine Waste Containing Titaniferous Minerals for the Recovery of Metals
||Stephen Parirenyatwa, Animesh Jha, Lidia Escudero Castejon, Sergio Sanchez-Segado, Yotamu Hara
|On-Site Speaker (Planned)
In a world where declining ore grades are increasingly common, it has become necessary to process low-grade feedstock. Carbothermic reduction in the presence of alkali (Na2CO3) has been adapted to beneficiate waste that contains titaniferous minerals (TiO2 ca.12 wt. %), in order to recover valuable constituents such as TiO2, Fe and V2O5. The waste from vanadium metal processing has environmental legacy as it leaves nearly 1 wt.% V2O5 process waste, which is environmentally problematic due to V5+ ions in contact with water and soil. This investigation focuses on the kinetics and mechanism for alkali reduction of mineral waste bearing 10-12 wt.% TiO¬2, which we studied in the 1073K-1323K range. The thermogravimetric analysis (TGA) technique was used to record weight loss data. Two distinct regimes demonstrated mixed-control kinetics: 1) at low temperatures the activation energy was found to be 199kJ.mol-1, which corresponds to the outward diffusion of O2- ions; and 2) at high temperatures the calculated value was 130kJ.mol-1, which is consistent with the activation energy for the outward diffusion of Fe2+ ions. The metallic iron, sodium titanate and sodium aluminosilicate phases that formed were characterised using X-ray powder diffraction (XPRD) and scanning electron microscopy (SEM) techniques, and their significance for metal recovery is explained.
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