USES OF MANGANESE
Alloys of manganese are essential in the manufacture of steel by the open-hearth and the Bessemer processes, which produce 99 per cent. of the total output of the United States. In this country, about 14 pounds of metallic manganese as alloys, equivalent to about 40 pounds of high-grade ore, is used in making a ton of average steel. Two alloys are in common use: ferromanganese and spiegeleisen. Ferromanganese, with 70 to 80 per cent. manganese, is largely used in making open-hearth steel carrying less than 0.30 per cent. carbon, whereas spiegeleisen, with 20 to 32 per cent. manganese, is used in making Bessemer steel carrying more than 0.30 per cent. carbon. The first group of low-carbon steels is used in making structural shapes, sheets, bars, wire, etc., and the second group of high-carbon steels is used in making rails, forgings, etc.
In making 70 to 80 per cent. ferromanganese, so-called “high-grade” ore with more than 35 per cent. manganese and less than 5 per cent. iron and 15 per cent. silica is needed. In making 20 to 32 per cent. spiegeleisen, so-called “low-grade” or ferruginous manganese ore with 10 to 35 per cent. manganese, 20 to 35 per cent. iron, and less than 20 per cent. silica is needed, although here and there spiegeleisen is made by mixing high-grade manganese ore with iron ore.
Several other alloys such as silico-manganese, ferro-silicon, and ferro-carbon-titanium may be used as partial substitutes for ferromanganese, but although they may be capable of wider use under stress, they are electric-furnace products and under normal conditions their cost is prohibitive.
Very pure manganese oxide is used in making the common dry battery, the production of which has greatly increased with the wide use of the internal-combustion engine. About 25,000 tons is used annually in the United States for this purpose. The manganese oxide thus used is not consumed, but becomes exhausted through the loss of oxygen. Under stress of high prices, the oxide may be regenerated by treatment or by mixture with new refined material.
Small quantities of manganese ore are used in making many chemical products and pigments.