Electrolytic recovery of molybdenum from molybdic oxide and molybenum sesquisulfide

An electrolytic process for molybdenum extraction in a KCl?K₃MoCl₄ electrolyte (containing approximately 7.5 wt pct molybdenum) was investigated using three types of anode feed —namely, molybdic oxide-graphite, molybdenum sesquisulfide-graphite, and molybdenum sesquisulfide without graphite. In the case of molybdic oxide-graphite anode, a maximum current efficiency of 99 pct was achieved at an operating voltage of 0.35V, a cathode current density of 5000 A/m² (450 A/f²) and a bath temperature of 1223 K. Electrolysis with molybdenum sesquisulfide-graphite, at an operating voltage of 1.2V, a cathode current density of 13,900 A/m² (1250 A/f²) and a bath temperature of 1173 K, yielded a maximum current efficiency of 84 pct. Electrolysis of molybdenum sesquisulfide without graphite incorporation, yielded under almost similar conditions, a maximum current efficiency of 87 pct. Extended electrolysis was carried out using molybdic oxide-graphite and molybdenum sesquisulfide cell charges and yielded metal with purity over 99.9 pct.