Abstract: A stable rhodochrosite comprising manganese carbonate (MnCO3) and 0.03-0.3 wt % of an anion or ligand of phosphoric acid (H3PO4), pyrophosphoric acid (H4P2O7), an organic acid, or a salt of such acids, or 0.03-0.3 wt % of a mixture of such anions and/or ligands. Also, a method of producing stable rhodochrosite comprising manganese carbonate (MnCO3) in which a rhodochrosite comprising manganese carbonate (MnCO3) is treated by applying an aqueous treatment solution of phosphoric acid (H3PO4), pyrophosphoric acid (H4P2O7), sulfuric acid (H2SO4), an organic acid, or a salt of such acids, or a mixture thereof and the treated rhodochrosite is dried to produce stable rhodochrosite.

Abstract: A stable rhodochrosite comprising manganese carbonate (MnCO3) and 0.03-0.3 wt % of an anion or ligand of phosphoric acid (H3PO4), pyrophosphoric acid (H4P2O7), an organic acid, or a salt of such acids, or 0.03-0.3 wt % of a mixture of such anions and/or ligands. Also, a method of producing stable rhodochrosite comprising manganese carbonate (MnCO3) in which a rhodochrosite comprising manganese carbonate (MnCO3) is treated by applying an aqueous treatment solution of phosphoric acid (H3PO4), pyrophosphoric acid (H4P2O7), sulfuric acid (H2SO4), an organic acid, or a salt of such acids, or a mixture thereof and the treated rhodochrosite is dried to produce stable rhodochrosite.

Abstract: A method of producing an oxide of manganese including reacting, in a first aqueous solution, a manganese salt and an alkali agent to form manganese hydroxide; separating the manganese hydroxide from the first solution; mixing the manganese hydroxide into an aqueous medium to form a manganese hydroxide suspension; mixing the manganese hydroxide suspension with alkali metal hydroxide to form a second aqueous solution; and oxidizing the manganese hydroxide in the second aqueous solution to form an oxide of manganese. The dried oxide of manganese includes birnessite, a maximum of 20% hausmannite, and a maximum of 10% feitknechtite, may further include a maximum of 400 ppm of anions, may have a specific surface area of at least 25 m2/g, and may have an average oxidation state of greater than 3.5.

Abstract: A method of producing an oxide of manganese including reacting, in a first aqueous solution, a manganese salt and an alkali agent to form manganese hydroxide; separating the manganese hydroxide from the first solution; mixing the manganese hydroxide into an aqueous medium to form a manganese hydroxide suspension; mixing the manganese hydroxide suspension with alkali metal hydroxide to form a second aqueous solution; and oxidizing the manganese hydroxide in the second aqueous solution to form an oxide of manganese. The dried oxide of manganese includes birnessite, a maximum of 20% hausmannite, and a maximum of 10% feitknechtite, may further include a maximum of 400 ppm of anions, may have a specific surface area of at least 25 m2/g, and may have an average oxidation state of greater than 3.5.