Separation and recovery of vanadium from spent vanadium pentaoxide catalyst by Cyanex 272

Abstract

The contact process preferably used vanadium pentaoxide as catalyst to increase the rate of reaction of producing sulphuric acid. Sulfuric acid plants regularly require catalyst replacement in order to cope with process improvements. The spent catalyst is considered as hazardous solid waste and cannot be discarded untreated owing to presence of high amount of vanadium and other associated metals. Because of significant environment implications of spent catalyst wastes, it is imperative to recover valuable metals present in them. The recovery of precious materials or metals from waste will not only help in mitigating environment problem due to metal pollution but also help improve the economy of the country. The purpose of this research work is to develop method to recover vanadium from spent V2O5 catalyst. The detailed study of extraction, separation and recovery of vanadium from leached spent catalyst solution of composition; V, 3.6% ; Al, 2.1%; Fe, 1.3%; Ti, 0.8% and less than 1 % of Cr and Pb is reported in this paper. Cyanex 272 (bis (2, 4, 4-trimethylpentyl) phosphinic acid) has been explored for the recovery of vanadium from spent V2O5 catalyst. The effects of different parameters like, pH, solvent concentration, organic to aqueous ratio etc. were optimised for the complete extraction and recovery of vanadium. The proposed procedure gives high purity vanadium with almost a quantitative yield (~99%) and of course free from closely associated metals. The extractants could be reused up to ten cycles with no significant change in the extraction capability.