Sustainable process design for high-purity MoO3 production from shale: An integrated process of solvent-impregnated biochar enrichment and low-temperature chlorination distillation

An integrated and environmentally friendly process combining solvent-impregnated biochar enrichment and chlorination distillation was developed to address challenges in recovering molybdenum from low-concentration acidic leachates and the use of chlorine gas in conventional chlorination methods. Initially, molybdenum was adsorbed from the leachate using solvent-impregnated biochar (SICB), achieving an adsorption efficiency of 98.91% and a saturated adsorption capacity of 53.850 mg/g under optimized conditions. The adsorbed molybdenum was desorbed with an ammonium bicarbonate solution of appropriate concentration. After evaporative concentration of the desorbed solution, the resulting solid was subjected to chlorination in an optimized molten salt system under optimal reaction conditions, producing MoO 2 Cl 2 with a purity exceeding 99.9%. This step effectively removed impurities such as sodium, potassium, and iron, while the low reaction temperature and avoidance of chlorine gas reduced energy consumption. Finally, using the aqueous solution of the high-purity MoO 2 Cl 2 as feedstock and melamine as the precipitating agent, MoO 3 with a purity of over 99.9% was successfully prepared. This integrated process enables efficient separation of molybdenum from impurities, eliminates the use of chlorine gas, and offers promising prospects for the comprehensive recovery of valuable metals from vanadium shale.