Rapid simultaneous recovery and purification of calcium and molybdenum from calcium molybdate-based crystal waste

Molybdenum (Mo) has wide applications like as alloying elements in steel industries and in experimental laboratories as a catalyst for organic synthesis and as scintillating crystals in high-energy physics experiments. The primary mineral resources of Mo have been ceaselessly exploited and are insufficient to meet the demand in manufacturing industries and experimental researches. Separation, purification, recovery and reuse of Mo will, therefore, be of great importance for environmental conservation and sustainable development. The objective of this study was to recover Mo and calcium (Ca) from crystal wastes. Mo and Ca were recovered from CaMoO₄ scintillating crystal wastes in the forms of MoO₃ and CaCO₃ by adopting nitric acid and hydrochloric acid leaching schemes. About 98% recovery yield efficiency for both elements was obtained through hydrochloric acid leaching. The concentrations of impurity elements like strontium, barium, lead, thorium and uranium in the final products were also reduced by several dozen times as compared to the initial wastes. The finding of this study showed that the hydrochloric acid leaching method could be applied for a rapid and efficient recovery of Mo and Ca from CaMoO₄ wastes on a large scale.