Kinetics of pressure oxidative leaching of molybdenite concentrate by nitric acid

The current study was carried out to investigate the kinetics of reactions for the pressure oxidative leaching of a molybdenite concentrate in less than one hour. The effects of oxygen pressure, stirring speed, pulp density, acid concentration and temperature on the leaching rate of the molybdenum were studied. It was found that about 85% of molybdenite was oxidized to molybdic oxide precipitate with remaining molybdenum dissolved in the leaching liquor. Analysis of experimental data showed that the reaction is chemically controlled with activation energy of 68.8 kJ/mol. Furthermore SEM images showed no significant boundary diffusion layer and it was noted that the molybdic oxide precipitates were of fibrous shape.

► The effect of parameters on pressure leaching of molybdenite concentrate was studied. ► Complete leaching of the molybdenite concentrates was achieved in less than one hour. ► Mechanism of the leaching reaction was determined. ► The amount of the reaction activation energy was calculated. ► The leaching precipitates were characterized by SEM and X-ray.