A Novel Technology Of Extracting Molybdenum From Dynamax By Oxidation Roasting And Water Leaching

Dynamax obtained by melting the Ni-Mo ore is a low grade molybdenum metallurgical material. In this paper, the extraction of molybdenum from dynamax was studied by roasting with Na2CO3 and CaO addition, followed by water leaching. The technological process consists of roasting with Na2CO3 and CaO addition, water leaching and recovery of molybdenum by ion exchange.The roasting experiment focused on studying the effect of the amount of additive (Na2CO3 and CaO), roasting tempreature and roasting time on the extraction of molybdenum. The behavior of impurities of phosphorus, arsenic and silicon were also studied. The results showed that the extraction of molybdenum reached 97.5%when 50g dynamax roasting with 17g Na2CO3 and 10g lime addition (CaO/Na2CO3 mole ratio of 0.75) at 700℃for 2h. The results also illustrated that the addition of CaO was in favor of the formation of insoluble substances Ca3(PO4)2, Ca3(As04)2 and CaSiO3. The leaching rate of phosphorus, arsenic and silicon were only 16.2%,18.1%and 41.2%respectively when dynamax roasted with CaO and Na2CO3 addition, while the leaching rate of phosphorus, arsenic and silicon were as high as 65.1%,74.4% and 81.0% respectively when dynamax roasted only Na2CO3 addition.The calcine obtained under the optimum roasting condition was leached with water by stirring with a consistent speed. In leaching process, the factors of leaching time, leaching temperature and liquid/solid ratio were studied. The leaching results showed that the optimum leaching conditions were 100℃leaching for 2h with liquid/solid ratio of 3:1 The impurities were maintained in the leached cake with the shape of Ca3(PO4)2, Ca3(AsO4)2 and CaSiO3.The weak base anion exchange resin D314 was used to enrich the molybdenum in leaching solution. The loaded resin was stripped by 6M ammonia. The results showed that the Mo could be absorbed effectively at pH=3.5. The loading of Mo on the resin was found to be as high as 141.5mg/ml wet resin with a maximum Mo concentrate of 153g/L in the eluate. It was found that impurities phosphorus, arsenic and silicon can form an especial heteropoly compounds with molybednum which can be absorbed in ion exchange process. The impurities phosphorus, arsenic and silicon which existed in dissociative form can be removed from the loaded resin by 0.8M HC1, however, phosphorus, arsenic and silicon bearing heteropoly compounds cannot be removed.