Comprehensive extraction of V, Ni and Mo from black shale via selective leaching oxidation process

Black shale is one of the most representative sources of vanadium, nickel and molybdenum in China. Due to the poor endowment of minerals in black shale, V, Ni, Mo and other metals complex co-associated endowment state, extraction is difficult and long-term unused, resulting in a significant waste of resources. In this paper, it is shown that V, Ni and Mo can be obtained from black shale by a stepwise oxidation leaching process. In a first leaching process, V and Ni are effectively leached simultaneously. Mo is left in the residue. The leaching efficiency of V, Ni and Mo was 86.81 %, 89.19 % and 5.80 % respectively under the leaching conditions of 35 wt% H 2 SO 4 , 4 wt% CaF 2 , 1.2:1 liquid to solid ratio (L/kg), 95℃ and 8 h. The residue was then leached twice. The leaching efficiency of molybdenum was 91.10 % under the leaching conditions of 25 wt% H 2 SO 4 , 8 wt% NaClO 3 , 1.5:1 liquid to solid ratio (L/kg), 45℃ and 7 h. V 2 O 5 products have been successfully prepared, the purity of V 2 O 5 reaches 98.34 %. A stepwise oxidation leaching method has been proposed to separate the vanadium, nickel and molybdenum in the leaching process. Vanadium, nickel and molybdenum can be effectively extracted from the black shale by the stepwise oxidation leaching process to maximize the utilization of the resources. • V, Ni and Mo are separated by stepwise oxidation leaching. • H 2 SO 4 leaching of black shale can realize the preliminary separation of V and Ni from Mo. • Mo is dissolved in the NaClO 3 -H 2 SO 4 oxidation acid leaching of Mo residue. • Proposing a stepwise oxidation process for Mo extraction.