Oxidation leaching of NiMoV alloy enriched from spent hydrogenation catalysts and solvent extraction of Mo and V

Abstract

Spent hydrogenation catalysts are strategic resources due to the high contents of Ni, Mo, and V. These metals were reduced and enriched as NiMoV alloy through pyrometallurgical smelting. However, it is a technical bottleneck for the separation of Ni, Mo and V from the polymetallic alloy. Hence, this paper proposed the atmospheric oxidation leaching of NiMoV alloy and separation of Ni, Mo and V through solvent extraction. The mixed solution of HCl and HNO3 was employed as the leaching reagent for the dissolution of the alloy. The leaching efficiencies of Ni, Mo and V were all exceed 99.5% under the optimal conditions: c(HCl) of 3.0 mol/L, c(HNO3) of 2.5 mol/L, S/L of 1:10 (g/mL), temperature of 95 °C for 3.0 h. N235 was used as the extractant for the synergistic extraction of V and Mo, while TBP and sulfonated kerosene was used as modifier and diluent. The extraction efficiencies of V and Mo were 99.2% and 99.9% under three-stage extraction of the following conditions: pH of 1.2, c(N235) of 25 vol%, and O/A of 1:1. It was found that only 0.01% Ni and 9.7% Fe entered the organic phase and can be removed by washing, which showed excellent selectivity for V and Mo. Then, based on the principle of ion exchange, H2SO4 and NH3·H2O were used to selectively strip V and Mo. Finally, V2O5, MoO3 and Ni(OH)2 were obtained after precipitation and calcination.