Method for preparing manganese sulfate by biomass self-heating reduction of low grade manganese oxide ore

The invention discloses a method for preparing manganese sulfate through the biomass self heating reduction of low-grade manganese oxide ore. The method comprises the following steps: 1) respectively crushing the low-grade manganese oxide ore and biomass material; 2) weighing the low-grade manganese oxide ore, the biomass material and an initiating additive according to the weight ratio of 100:10-30: 0.5-3; 3) mixing evenly and roasting the low-grade manganese oxide ore, the biomass material and the initiating additive; 4) leaching the roasted mass through dilute sulfuric acid at a temperature of between 40 and 80 DEG C, regulating the mixed liquor to make the pH value more than or equal to 6, carrying out solid-liquid separation, and keeping the obtained filtrate for standby; and 5) removing impurities from the filtrate to obtain the manganese sulfate solution. The method adopts renewable energy source of the biomass material to replace coal to reduce the manganese oxide ore and prepare manganese sulfate which can be the raw material for producing electrolytic manganese. The leaching efficiency of manganese can reach more than 95 percent. The method not only saves energy sources, but also reduces the production cost.