Study On The Kinetics Of Reductive Leaching Processes Of Manganese Oxide Ores Using Biomass As Reductants And Their Applications

With the rapid development of Chinese electrolytic manganese metal (EMM) industry, the shortage and lower grade of manganese carbonate ores have become the main problems that restrict the sustainable development of manganese industry. Therefore, research on efficient and economical exploitation of manganese oxide ores is of great significance to alleviating the serious shortage of contradictions in china’s manganese resources. The technological conditions and kinetics of reductive leaching of manganese oxide ores in the presence of different biomass such as cellulose were investigated in this paper, which can provide theoretical basis for other reductive leaching processes of manganese oxide ores and are useful for promoting technological progress of EMM industry.The leaching kinetics of manganese from manganese oxide ores was studied in dilute sulfuric acid solution using cellulose and calcium lignosulfonate as reductants. Effects of stirring speed, temperature, the consumption of reduction, the initial sulfuric acid concentration and reaction time were investigated. The kinetics data were analyzed with the support of the shrinking core model. It was indicated that when using cellulose as reductant, the leaching process was dominated by both internal diffusion and chemical reaction at the initial stage, with the progress of leaching reaction, the rate-controlling step switched to the internal diffusion, and an Arrhenius law was used to relate temperature to apparent leaching rate constant, from which apparent activation energies were calculated to be46.487kJ/mol in the first60minutes, and62.290kJ/mol in the later90minutes. It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate. Besides, the kinetics model of reductive leaching of manganese oxide ores using calcium lignosulfonate as reductant was in agreement with internal diffusion control with an apparent activation energy of48.36kJ/mol. The reaction orders were1.30and1.73for calcium lignosulfonate and sulfuric acid, respectively.The reductive leaching processes of XiangXi of Hunan manganese oxide ores using bamboo sawdust and waste tobacco concrete as reductants were carried out. Effects of stirring speed, temperature, reductant concentration, the sulfuric acid concentration and reaction time on manganese extraction concentration were discussed. The extraction ratio of manganese from manganese oxide ores reached above85%under the optimal conditions. The slurry electrolysis of manganese oxide ores using waste tobacco concrete as reductant has been studied. The surface status of the cathode manganese was observed by scanning electron microscopy (SEM), and the purity of it was investigated by X-ray diffraction spectroscopy (XRD). It was found that electrolytic manganese metal particles were uniformly dispersed and tightly packed with the particle size of about0.5μm. The obtain manganese-chip on the cathode plate was a surface smooth and silver-white metal.