Capítulo

An investigation on the kinetics and mechanism of alkali reduction of mine waste containing titaniferous minerals for the recovery of metals

Book Series ch
Minerals, Metals and Materials Series
  • Número: 9783319510903
  • Fecha: 01 enero 2017
  • Páginas: 465-474
  • ISSN: 23671696 23671181
  • Tipo de fuente: Serie de libros
  • DOI: 10.1007/978-3-319-51091-0_45
  • Tipo de documento: Capítulo
  • Editorial: Springer International Publishing
© 2017, The Minerals, Metals & Materials Society.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% TiO2, which we studied in the 1073¿1323 K 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 199 kJ mol¿1, which corresponds to the outward diffusion of O2¿ ions; and (2) at high temperatures the calculated value was 130 kJ 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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