KINETICS OF THE AQUEOUS OXIDATION OF MOLYBDENITE AND THE ROLE OF CRYSTAL ANISOTROPY ON THE ELECTROCHEMICAL MECHANISMS OF THE PROCESS

The dissolution of molybdenite in alkaline hypochlorite solutions is studied from a kinetic viewpoint. The observed rate of dissolution is interpreted in terms of a pore diffusion model and suggests a heterogeneous chemical reaction constant of the order of 10('-6) cm/sec. The morphological and electrochemical studies that have been undertaken in this work serve to delineate the mechanism of progress of the dissolution reaction, and provide the basis for the understanding of molybdenite nobility, and rate limiting phenomena.; Molybdenite dissolution is extremely anisotropic in character, showing the three fold symmetry of the hexagonal structure in hypochlorite dissolution. An electrochemical mechanism applies, with the anodic reaction restricted to crystal edges. This reaction sequence is anodically controlled, with the rate of hole transfer being the critical step.