Hydrometallurgical investigation routed through microwave (MW) assisted leaching and solvent extraction using ionic liquids for extraction and recovery of molybdenum from spent desulphurization catalyst

The integrated hydrometallurgical approach routed through Microwave (MW) assisted leaching-cum-solvent extraction-precipitation for recovery of MoO3 from spent desulphurization catalyst was investigated. Selective separation of molybdenum (Mo) was obtained using the ionic liquid as Cyphos 104. In leaching study the role of MW power and H2SO4 concentration appears to be critical on transforming sulphide and oxide phase of metals (Mo, Al and Ni) in the spent catalyst phase into respective metal sulphate that led to have enhancement of metal leaching efficiency. At the optimum leaching condition: MW power of 1000Watt, 10(V/V)% H2SO4, 10(W/V)% (S/L) more than 99 % of Mo, 98 % of Al and 99 % of Ni was extracted with dilute acid. The leach liquor bearing 10.01 g/L of Mo, 27 g/L of Al and 2 g/L of Ni was subjected to Mo extraction using the ionic liquid(IL) of Cyphos 104. The molybdenum found to exist as H2MoO4 in the aqueous solution at pH 2.0 and observed to be suitable condition for extraction of Mo by IL ensuring its selective extraction. The association of 1.0 mol of IL was ascertained from slope analysis result for extraction of Mo from the aqueous medium. The extraction isotherm investigation predicts on need of 2 no. of stages of at A: O = 7:2, pH 2.0 using 0.2 M of Cyphos 104 and was validated by 6-cycles counter current simulation (CCS) for quantitative extraction of Mo. The loaded Mo was stripped with NH4OH for regeneration of ILs and enrichment of Mo up to 2.5 folds followed by recovery of MoO3 through crystallization-precipitation approach and was confirmed by XRD analysis.