Metallurgy: (Mn) as ore concentrates and/or ferro manganese & silico manganese derived from the ores is ubiquitous in the production of cast iron & steel. Iron ore, coke, and limestone are the basic feed materials used to manufacture pig iron – as coke burns it acts as the fuel to heat the blast furnace and at the same time gives off carbon monoxide which combines with the iron oxides in the ore reducing them to pig iron:
Fe2O3 + 3CO &#-3864; 3CO2 + 2Fe
Molten & cold pig iron, mixed with scrap steel, limestone, iron are, fluorspar, & Mn, is the furnace feed for steel production. The manganese has multiple functions as it combines with and removes the residual sulfur, acts as a mild deoxidizer, controls the morphology of sulfides, and has an alloying affect to increase strength, toughness, and hardness of the steel. The manganese content is varied depending on the desired properties of finished products for example 1 % Mn for carbon steels [various machinery, automobile bodies, structural steel for buildings, ship hulls, etc.]: as much as 10% Mn for stainless stell [pipes & tanks for petroleum refineries and chemical plants, aircraft parts, surgical Instruments & equipment, bone replacement parts, kitchen & food, preparation plant etc.] and up to 14 % Mn for extremely hard and abrasion-resistant steels such as High-Strength Low-Alloy (HSLA) steels [rail freight cars, building frameworks, etc.]: alloy steels [automobile gears & axles, roller skates, carving knives, etc.]: and tool steels [various types of tools or the cutting & shaping parts of power-driven machinery].
Mn added to nonferrous metals improve properties such as hot and cold strengths, resistance to corrosion, and formability. Major alloys and uses are varied and include Al-Mn & Al-Mn-Mg [cookware, drink cans, roofing, automobiles]: Cu-Mn [bimetallic strips for temperature control devices]: Cu-Mn-Ni [nonmagnetic, high-strength alloy for watch parts]; Mg-Mn [electronic parts]: Mn-Ti [spacecraft control module]. An average beverage can contain 1 % manganes.
Most Mn ore used in steel making is converted first to ferromanganese or less commonly silicomanganese or Mn metal. Ferromanganese, either as a high- (a.k.a. carbure), medium- (affine), or low- (suraffine) carbon grade, is made by smelting blended Mn ores & coke with or without lime and/or magnesia in a blast furnace or an electric submerged-arc furnace [various steels including carbon, HS-LA, stainless & heat resisting, electrical, tool, full alloy, cast irons, superalloys]. A similar electronic-furnace process is used to make silicomanganese, an alloy of manganese & iron containing 12.5 to 18.5% silicon, smelting of ferromanganese [steel & iron making]. Mn metal is produced by acid leaching roasted Mn ore or byproduct MnO from ferromanganese slag, neutralizing the product with ammonia to precipitate out iron & aluminum, followed by filtration, purification, and electrolyze in a diaphragm cell. The 99.9% pure product, made up of silver-gray, irregular, and brittle flakes about 3 mm thick, is finely ground and compacted with granulated aluminum to form 75% Mn/25% Al briquettes aluminum production, steel manufacture].
Manganese dioxide: Activated MnO2 is produced by heating ground ore to 600-800°C and adding sulfuric acid to form a porous, hydrated, and chemically active product. Chemical MnO2 (CMD) is obtained by the thermal decomposition of a manganese compound other than an oxide (the SEDEMA process). Electrolytic MnO2 (EMD) is prepared by anodic oxidation of manganese sulfate in sulfuric acid solution.