Manganese dioxide (chemical formula: MnO2) is a black or brown solid, the most stable oxide of manganese, and is often found in pyrolusite and manganese nodules. Pylusite is the main mineral containing manganese; manganese nodules (submarine rock solids) also contain manganese. Manganese dioxide is mainly used to make dry batteries, such as carbon-zinc batteries and alkaline batteries; it is also often used as a catalyst in chemical reactions, such as making oxygen; or as a strong oxidant in acidic solutions. It can also be used as a reagent (oxidant) in organic synthesis, for example, for the oxidation of allyl alcohol. Manganese dioxide is also used as a pigment and as a precursor for other manganese compounds such as potassium permanganate (KMnO4). Manganese dioxide in the alpha polymorph can incorporate various atoms (as well as water molecules) in "tunnels" or "channels" between the manganese oxide octahedra(s). There is considerable interest in the possibility of α-MnO2 as a cathode for Li-ion batteries.

Many polymorphs of manganese dioxide, as well as hydrated forms, have been proposed. Manganese dioxide, like many other dioxides, crystallizes in the rutile crystal structure (this polymorph is called β-MnO2), with tricoordinate oxides and octahedral metal centers. Manganese dioxide is a typical non-compound compound with oxygen atom vacancies. This complex solid-state compound is related to the "new preparation" of manganese dioxide in organic synthesis. It should be noted that the alpha-polymorph of manganese dioxide has a very open structure with "channels" that can accommodate metal atoms, such as silver or barium. It is commonly referred to as Hollandite after the closely related associated minerals.

How to make the manganese dioxide?

Natural manganese dioxide contains impurities and a large amount of Manganese(III) oxide. Only a few deposits contain gamma crystals of sufficient purity for the battery industry.

High-purity manganese dioxide is required for the production of batteries and ferrite (the two main uses of manganese dioxide). What is needed to produce batteries is "electrolytic grade manganese dioxide"; and "chemical grade manganese dioxide" is needed to produce ferrites.

A new method for purifying by-product manganese dioxide is characterized in that comprising the following steps:

(1) Treat crude MnO with 15-20% dilute sulfuric acid, wherein MnCO or MnO mixed in MnO can be dissolved to generate MnSO, while a small amount of a and P crystal forms in crude MnO transform to Y-type, thereby improving the activity and purity of MnO ;

(2) above-mentioned liquid of oxidation treatment, to step (1), add 2-3% strong oxidant ammonium persulfate in the liquid containing manganese dioxide, be heated to 45-50 ℃, stir 20-30min, the Mn in solution Converted into MnO2;

(3) the solution that step (2) is handled is filtered, washed, oven dry to obtain product refined manganese dioxide.