Reductive Leaching Process And Mechanism Of Manganese Oxide Ores Using Biomass As Reductants

With the increasing shortage of high-quality manganese carbonate ores resources, it will be of great practical significance for manganese oxide ores to find an environmentally friendly and high efficiency leaching process. Biomass reductants are kinds of resources with the property of environmentally protection, low cost and wide raw material. The reductive processes using biomass as reductants for leaching manganese oxide ores have been investigated.The reductive leaching processes of Gabonese and the western of Hunan manganese oxide ores using waste tea-leaf, cane tea, robinia and phytolaccaceae as reductants were carried out. The effects of reductants concentration, concentration of sulfuric acid, liquid-solid ratio, leaching temperature and reaction time on the processes were discussed. The leaching efficiency of manganese from Gabonese manganese oxide ores reached above95%under the optimal conditions which were determined as reductants concentration of50-70g/L, sulfuric acid concentration of2.5-2.8mol/L, liquid-solid ratio of5:1～7:1, stirring speed of400r/min, leaching temperature of95℃for8h. The optimal conditions of the western of Hunan manganese oxide ores as follows:reductants concentration18-27g/L, sulfuric acid concentration1.4～1.7mol/L liquid-solid ratio5:1-7:1, stirring speed400r/min, leaching temperature95℃, reaction time8h, and the leaching efficiency of manganese reached above94%.The results from the leaching processes showed that ordinal relation as follow:cane tea> robinia> waste tea-leaf> phytolaccaceae. The kinetics of the leaching processes was investigated with chemical reaction and diffusion control models. The results concluded that the rate was controlled by internal diffusion with the apparent activation energy of5-50kJ/mol, which indicated that the reductant concentration, temperature and sulfuric acid concentration have important effect on leaching processes compared with stirring speed. The dynamic equation of the leaching process of manganese oxide ores using phytolaccaceae as reductant was set up.