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Abstract

Provided is a method for producing mercury-free alkaline-manganese type electrolyzed manganese dioxide, which sequentially comprises: (1) mixing manganese oxide ore and pyrite, continuously feeding the mixture and sulfuric acid into a continuous leaching tank to form a one-stage or multi-stage continuous leaching, removing potassium ions first after leaching, and then removing iron by means of a neutral iron removal method, and adding lime powder at the late stage of iron removal to adjust the pH value of the solution to 6-6.5, so as to obtain a manganese sulfate solution after reaction at 90-95° C. for 3-4 hours; (2) performing purification and impurities removal on the manganese sulfate solution by a two-stage continuous purification process, wherein, during the first stage of the continuous purification on the manganese sulfate solution, calcium polysulfide is added, and during the second stage of the purification, the solution passes through a sluice and calcium and magnesium are dynamically removed, and then the solution is sent to a still tank to stand to deposit and remove impurities such as calcium and magnesium; and (3) subjecting the purified manganese sulfate solution to ultra-fine filtering, heating to 90-100° C. by a plate heat exchanger, and then entering an elevated tank, and at the same time, adding a prepared suspending agent and a prepared foaming agent, and supplying the resulting product to electrolysis baths through pipelines for electrolysis, so as to obtain mercury-free alkaline-manganese type electrolyzed manganese dioxide. The method has the advantages of wide adaptability to manganese oxide ores, short process flow, and low production cost.

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