Kinetics of reductive leaching of manganese oxide ore with molasses in nitric acid solution

The kinetics of reductive leaching of manganese from a low grade manganese ore in dilute nitric acid in the presence of molasses is examined. The rate is controlled by diffusion through the “product” layer composed of the associated minerals. The leaching process follows the kinetic model 1 − 2/3X − (1 − X)2/3 = kt with an apparent activation energy of 25.7 kJ/mole. It is concluded that the concentration of HNO3 and molasses as well as temperature are the main factors influencing the leaching rate. The results indicate a reaction order of 1.2 for HNO3 concentration and 1.9 for molasses concentration.