Method of producing manganese dioxide

Claim 1

A method of producing manganese dioxide which comprises the steps of a. pouring an aqueous solution of a soluble manganese salt and an aqueous solution of alkali carbonate separately and simultaneously into a reaction vessel and gradually mixing the two solutions by agitating at a crystal precipitation temperature ranging from room temperature to 90* C. so that the two solutions may react with each other to produce manganese carbonate, said aqueous solution of alkali carbonate being selected from the group consisting of (1) sodium carbonate and sodium bicarbonate in a range of proportion of 6:4 to 0:10 and (2) ammonium carbonate and ammonium bicarbonate in a range of proportion of 9.6:0.4 to 0:10; b. heating the manganese carbonate produced by the preceding step to 300* to 450* C. in atmosphere air after adding an aqueous solution of an alkali such as caustic soda, caustic potash or the like to produce crude manganese dioxide having an apparent rate of charge density of above 1.6 grams per cubic centimeter; and c. Causing the crude manganese dioxide produced by the preceding step to be impregnated with dilute or concentrated nitric acid in an amount which is 0.5 to 1.5 times as much as the divalent manganese contained in said crude manganese dioxide, heating the crude manganese dioxide impregnated with nitric acid at a temperature range from 40* C. to the boiling point temperature of nitric acid, followed by further heating to a range from 160* to 300* C. to produce manganese dioxide.

Claim 2

A method of producing manganese dioxide comprising the steps of a. pouring an aqueous solution of a soluble manganese salt and an aqueous solution of alkali carbonate separately and simultaneously into a reaction vessel and gradually mixing the two solutions by agitating at a crystal precipitation temperature ranging from room temperature to 90* C. so that the two solutions may react with each other to produce manganese carbonate, said aqueous solution of alkali carbonate being selected from the group consisting of (1) sodium carbonate and sodium bicarbonate in a range of proportion of 6:4 to 0:10 and (2) ammonium carbonate and ammonium bicarbonate in a range of proportion of 9.6:0.4 to 0:10; b. heating the manganese carbonate produced by the preceding step to a range from 280* to 400* C. in an atmosphere containing 10 to 80 percent by volume of water vapor to produce crude manganese dioxide having an apparent rate of charge density of above 1.6 grams per cubic centimeter; and c. Adding 40 to 80 percent concentrated sulfuric acid to the crude manganese dioxide produced by the preceding step and heating the crude manganese dioxide to 50* to 110* C. so as thereby to remove divalent manganese by elution, thus producing manganese dioxide of high MnO2 content.