Manganese dioxide is an inorganic compound with the formula MnO2. It is a blackish or brown solid. The main ore of manganese, mineral pyrolusite, which is a naturally a occurring manganese species, is attractive for its ability to attract heavy metals, such as iron and manganese as well as for the co-precipitation of arsenic.
Manganese dioxide is produced by mixing a manganous salt with alkali metal permanganate and/or ammonium permanganate. Reaction mixture is then heated to about 150°C in atmosphere containing oxygen until more than 85% of the manganous salt is converted to manganese dioxide and then further elevating the temperature to about 250°C.
Manganese dioxide is used in metallurgy industry as a melting agent in welding fluxes, electrode coatings and casting powders; to prevent absorption of manganese from the metal by the slag; improves the adhesion between the metal and the enamel top layer.
MnO2 is used for dry cell batteries, such as the alkaline battery and the zinc-carbon battery.
In the glass industry, it is used as colour pigment for purple and black glass, it promotes oxidation of organic components.
In the construction industry, MnO2 is used for the production of sand and cement, as a pigment for concrete.
Manganese dioxide is used as a drying agent; it catalyzes the oxidation of oils in paints and varnishes.