Recovery of vanadium values from titaniferrous magnetite ore of masanikere origin

Abstract

Vanadium has received world-wide attention in view of its excellent combination of properties such as high temperature strength, high thermal conductivity, favourable strength to weigh ratio, corrosion resistance, creep strength and low inelastic scattering cross section of neutrons. Major application of vanadium is as an alloy additive to various grades of steels, aerospace, as a potential material in nuclear engineering, super conducting materials and magnetic alloys. In India, there are no primary resources of vanadium and there is no indigenous commercial production. Secondary resources of vanadium like Bayer's sludge, titaniferrous magnetite, red mud and vanadiferrous titanates are therefore, presently being explored to develop techno-economically viable routes for the extraction of vanadium. This paper reports on laboratory work for the development of a process flowsheet for the recovery of vanadium values from the titaniferrous magnetite ore (TMO). The estimated reserves of TMO are of 3.4 MT, and located in the Masanikere region of Karnataka State in India. As received titaniferrous magnetite ore containing 48% iron (as its oxides) on hydrogen reduction, resulted in the improvement in the vanadium concentration in the residual ore from 0.84 to about 4.1% and formed the feed for subsequent processing for vanadium extraction. The process flowsheet developed essentially consists of (1) salt roasting of TMO under oxidizing atmosphere, (2) hot water leaching of the roasted mass, (3) precipitation of ammonium metavanadate cake from the leached liquor, and (4) calcination of the cake to vanadium pentoxide. The influence of various process parameters during each stage of the flowsheet has been studied in detail. It has been found that it is possible to prepare 99.5% pure vanadium pentoxide. The processing steps involve roasting of TMO with 100% excess NaCl at a temperature of 950 C for 4 hours under oxygen atmosphere, leaching of the roasted mass at 60 C, precipitation of ammonium metavanadate cake at pH 9 and finally calcination of the cake at 500 C. The overall recovery has been found to be 95%.