Reduction of low-grade manganese oxide ore by biomass roasting

The reduction process of manganese dioxide in low-grade manganese ore by biomass roasting was investigated.The calcine of manganese oxide ore was further leached by sulphuric acid, the manganese in ore can be converted into manganese sulfate.Effects of the mass ratio of manganese ore to sawdust, roasting temperature and time, leaching temperature and time, leaching agent concentration and liquid-solid ratio were studied.97.71% of manganese recovery can be achieved under the optimal conditions：the mass ratio of manganese ore to sawdust of 5：1, roasting temperature at 500℃ for 40 min, leaching temperature at 60℃ for 40 min, sulphuric acid concentration of 1 mol/L and liquid-solid ratio of 10：1.Other types of low-grade manganese ore like Guilin ore, Nanning ore and Gongcheng ore were tested and the same results were obtained.

Reduction of Low-grade Manganese Dioxide Ore Pellets by Biomass Wheat Stalk

An investigation on reducing low-grade manganese dioxide ore pellets was carried out by using wheat stalk as reductant. The main impact factors of reduction percent such as particle size, biomass/ore ratio, heating rate, nitrogen flow rate, temperature and time in reduction process were discussed. The morphology and component of manganese dioxide ore particle at different stages were also analyzed by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS）. The results show the increase of the reduction temperature and time, biomass/ore ratio, and the decrease of particle size, heating rate and nitrogen flow rate can significantly enhance reduction efficiency. The reduction kinetic of the manganese ore is controlled by three-dimensional mass diffusion of gaseous reductive volatiles passing from the surface to the core of the ore particles. The activation energy E and frequency factor A were calculated to be 24.15 kJ.mol^-1 and 166 min^-1, respectively. Biomass pyrolysis volatiles adsorbed onto the surface of the ore particle leads to serious variation of the microstructures and chemical composition of the manganese ore particles.

An investigation on stability of biomass reduced manganese dioxide ore

In this study, how to improve the stability of reduced manganese oxide ore was dis- cussed by investigating reoxidation conditions and kinetics mechanism in the cooling process of manganese dioxide ore reduced by biomass. The effects of the temperature and time, chip size of biomass, raw materials thickness and different additives on stability of the products were determined. The valence variation of manganese in ore and the reoxidation kinetics of reduced products were studied. The results show that decrease of reduction temperature and time, and increase of raw materials thickness and little H2SO4 additive are favorable for the stability of the reduced products. The kinetics mechanism of the reoxidation is controlled by diffusion with dynamic appar- ent activation energy of E1--25.10 kJ.mol-1, and conformation of manganese in the process is changed from MnO to Mn3O4.