Abstract:A direct alkaline leaching process was proposed to extract molybdenum and lead from low-grade wulfenite ore containing 2.87% Mo and 9.39% Pb. The results show that increasing temperature and alkali concentration enhances the extraction of Mo and Pb, and more than 99.7% of Mo and 64.6% of Pb are extracted under conditions of 75 °C, L/S of 2:1, leaching time of 1.0 h, initial NaOH concentration of 80 g/L and stirring speed of 100 r/min. The alkaline leaching of molybdenum follows a chemical reaction control mechanism with activation energy of 46.3 kJ/mol. Lead in the residue is recovered by hydrochloric acid leaching. 99.8% of lead is leached under the conditions of 80 °C, [MnO₂]/[Pb] molar ratio of 1.3:1, sodium chloride concentration of 40 g/L, and hydrochloric acid concentration of 3 mol/L, and a product of crystallized PbCl₂ with purity higher than 99.5% is obtained after cooling.

Key words: wulfenite; molybdenum; lead; leaching; kinetics