Recovery of molybdenum from spent catalyst leach solutions by solvent extraction with LIX 84-I

Abstract

The leach liquor (10 g/L Mo, 27 g/L Al, 2.0 g/L Ni) obtained from the baking and leaching process of spent catalyst was treated using solvent extraction to recover Mo(VI) by LIX 84-I. The influence of various basic variables such as pH, concentration of LIX 84-I, different stripping reagents, phase ratio and diluents, was examined. Using 40% LIX 84-I with the aqueous solution of pH 0.5 and a phase ratio O:A = 1:1, a two-stage McCabe–Thiele plot was constructed which showed 99.9% of Mo extraction with no co-extraction of Ni and Al. This was confirmed by a 6-cycle counter current simulation (CCS) study. The stripping of Mo(VI) was quantitative using a mixture of 1 M NH 4OH + 1 M (NH 4) 2CO 3. The counter current simulation condition (three stages, phase ratio O:A = 5:1) obtained from the stripping isotherm study further attributes to the enrichment (5 times) of Mo(VI) concentration in the strip solution. The stable complex MoO 2R 2 formed during extraction which supports the cation exchange mechanism, was confirmed by IR spectral analysis.