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Kinetics of Reduction Roasting of Low-grade Manganese Dioxide Ore in the Novel Four-tube Reduction Finance

The kinetics of reduction roasting of low-grade manganese dioxide ore used in this work has been established with four-tube reduction finance. XRD analysis of the as-mined ore samples affirmed the presence of manganese dioxide as the major manganese mineral in the ore. Samples with particles size ranges -5mm were treated using coal as the reductant. The effects of reduction temperature, time and mass ratio of coal to low-grade manganese dioxide ore on the rate of reduction were investigated. It was found that the optimum manganese reduction rate could be up to 93.05% under the conditions that the mass ratio of coal to manganese dioxide ore was 0.12:1, the roasting temperature was 850oC, and the roasting time was 20min. An unreacted shrinking-core model was proposed to describe the kinetics of reduction. Based on experimental results, It was confirmed that the reduction process was controlled by diffusion through the ash/inert solid layer. The apparent activation energy was determined to be 106.65 kJ /mol.