This article investigated molybdenum recovery from oxygen pressure water leaching residue of Ni-Mo ore using alkaline leaching, followed by chemical treatment of leach liquor. Parameters affecting Mo leaching rate, such as sodium hydroxide concentration, reaction time, a liquid-to-solid ratio, and temperature for the preliminary alkaline leaching were experimentally determined. The results showed that more than 88% of molybdenum was leached under the optimum conditions (2.5 ml·g-1 NaOH, 80 °C, a liquid to solid ratio 3 ml·g-1 , and reaction time 3 h). After the purification of leach liquor, a CaMoO 4 product of 99.2% purity could be obtained by CaCl 2 precipitation method. The whole Mo recovery reached about 82.7%.
