Method for preparing high-purity manganese carbonate through comprehensive utilization of mid-low-grade pyrolusite

The invention provides a method for preparing high-purity manganese carbonate through comprehensive utilization of mid-low-grade pyrolusite. The method specifically comprises the following steps of 1 preparing base materials of N-P compound fertilizer; 2 recovering ferric phosphate powder; 3 recovering cobalt-nickel-copper concentrate; 4 preparing aluminum hydroxide products; 5 recovering gypsum powder; 6 preparing high-purity manganese carbonate powder; 7 preparing magnesium ammonium phosphate slow-release compound fertilizer. According to the method, a mode that the mid-low-grade pyrolusite is directly utilized comprehensively without being processed through enrichment and reduction roasting is adopted, not only is the high-purity manganese carbonate prepared, but also the products such as the ferric phosphate powder and the cobalt-nickel-copper heavy metal sulfuration concentrate are obtained, the mid-low-grade pyrolusite is fully utilized, and the discharge effect of being free of sewage and waste residues is achieved; in addition, the mid-low-grade pyrolusite is adopted to serve as the raw materials, therefore, the low-grade manganese ore resources can be fully utilized, and the problem that the high-grade pyrolusite resources are in short increasingly.