Study of the kinetics of the magnesium leaching from serpentine bearing chromite overburden rocks for mineral carbonation

Characterisation and leaching studies have been carried out on serpentinite rock samples collected from Sukinda mines, India. Dissolution characteristics of samples have been studied using HCl, H2SO4 and HNO3 acid. Effect of particle sizes, solvent concentrations, reaction temperatures and reaction time have been investigated. It was found that Mg recoveries vary between 54.95% and 98.12%. Leaching of fine particles of <53 mu m sizes using H2SO2 solution of 1 M at 70 degrees C for 2 h can recover maximum 93% Mg with lowest Si content (6.6%). Kinetic studies indicated that dissolution of Mg follows product layer diffusion mechanism and activation energy calculated was 37.88 kJ mol(-1). CO2 treatment of leach liquor resulted in precipitation of magnesium carbonates and hydroxides at a solution pH adjustment between 7 and 10. The study revealed that these rocks can be used for CO2 fixation and H2SO4 can be the best solvent.