Recovery and purification of molybdenum from Ni–Mo ore by direct air oxidation in alkaline solution

Abstract

A direct hydrometallurgical process for molybdenum extraction and recovery from a Ni–Mo ore is reported. The novel technology includes leaching molybdenum by air oxidation in alkaline solution，purifying the leach solution with freshly precipitated “nascent” Fe(OH) 3 and “buffer agent” NaHCO 3, enriching molybdenum by ion exchange and crystallizing ammonium molybdate tetrahydrate. Compared with the traditional roasting methods for such ores, this new technology avoids SO 2 and As 2O 3 pollution problems. More than 98% Mo was leached in the process and through selective adsorption, about 95% W could be removed from the molybdenum leach solution under the optimized conditions. The Mo/W separation factor was up to 100. Impurities of V, As and P were simultaneously removed, along with W, with efficiencies reaching 95.5%, 99.7% and 57.1%, respectively. The final product of ammonium molybdate tetrahydrate was in accord with the standard specification (GB/T 3460–1982).