Recovery of pure MnSO4•H2O by reductive leaching of manganese from pyrolusite ore by sulfuric acid and hydrogen peroxide

Manganese leaching and recovery from pyrolusite ore, was investigated by using H2SO4 as a leachant and H2O2 as a reducing agent. The effects of agitation, H2O2 concentration, H2SO4 concentration, liquid/solid mass ratio. leaching time and reaction temperature on manganese recovery were studied. The optimal leaching conditions were determined as 4.0 M H2SO4 and 0.8 M H2O2 using liquid-solid mass ratio of 5.0 for 90 min at 40 degrees C and ore particle size of 44-37 mu m. Under these conditions, the leaching efficiency was 92.0% for Mn. It was found that the use of H2O2 as a reducing agent for the reductive leaching of manganese increased the leaching rate. Analysis of the experimental results indicted that the leaching process is fitted by a chemical reaction model in temperature range 20-40 degrees C, and at higher temperature, 45-70 degrees C, the diffusion reaction model prevails. Activation energies for these models were calculated to be 49.5 kJ.mol(-1) and 10.6 kJ.mol(-1), respectively. Based on the experimental results, a separation method and flow sheet were developed and tested to separate high purity MnSO4 center dot H2O (>99.4%). Comparison between the present results and that reported in the literature are given. (C) 2011 Elsevier B.V. All rights reserved.