Kinetics and mechanism of selective leaching of bismuth from molybdenite and bismuthinite mixed ore

Abstract

In the conventional beneficiation process for handling mixed ore containing molybdenite and bismuthinite, the co-extraction issues involving molybdenum and bismuth, exemplified by mutual content of molybdenite and bismuthinite, may lead to the shutdown of the production line. Under acidic conditions, Bi3+ and Cl− can form stable coordination complex anions, whereas Mo4+, Mo6+, and Cl− do not exhibit this behavior. This insight offers a novel approach for the chemical separation of molybdenum and bismuth from mixed ore using hydrochloric acid. Through a kinetic study of the hydrochloric acid leaching process applied to bismuth extraction from mixed molybdenite and bismuthinite ore, we have investigated various factors that influence leaching efficiency, such as stirring speed, particle size, acid concentration, and reaction temperature. Experimental results and computational results have revealed that the apparent activation energy is 56 kJ mol−1. The kinetic analysis suggests that the leaching process is governed by the product layer diffusion model. Moreover, the use of hydrochloric acid in leaching the mixed ore is shown to alter the surface structure, thereby increasing the effective reaction area. This, in turn, leads to improved leaching efficiency and enhances the overall leaching process.