Manganese CAS: 7439-96-5.
Metallic element of atomic number 25; Group VIIB of Periodic Table; aw 64.9380; valences = 2, 3, 4, 6, 7; no stable isotopes; four artificial radioisotopes.
Properties: There are four allotropic forms of which alpha is most important. Brittle silvery metal, d 7.44, Mohs hardness 5, mp 1245C, bp 2097C, decomposes water, readily dissolves in dilute mineral acids. Pure manganese cannot be fabricated. Manganese is considered essential for plant and animal life.
Occurrence: Usually associated with iron ores in submarginal concentration. Important ores of manganese are pyrolusite, manganite, psilome- lane, rhodochrosite. An important source of manganese is open-hearth slags. Ores occur chiefly in Brazil, India, South Africa, Gabon, Ghana, Zaire, Montana; 90% of US consumption is imported. So-called nodules rich in manganese and containing also cobalt, nickel, and copper have been found in huge quantities (estimated at 1.5 trillion tons) on the floor of the Pacific south of Hawaii. Such nodules have been located in other areas, as well as in Lake Michigan.
Derivation: Reduction of the oxide with aluminum or carbon. Pure manganese is obtained electrolyt- ically from sulfate or chloride solution.
Grade: Technical, pure or electrolytic, powdered. Hazard: Dust or powder is flammable. Use dry chemical to extinguish. Toxic. TLV (fume): 1 mg/m³ of air; (metal and most compounds): CL of 5 mg/m³ of air.
Use: Ferroalloys (steel manufacture), nonferrous alloys (improved corrosion resistance and hard- ness), high-purity salt for various chemical uses, purifying and scavenging agent in metal produc- tion, manufacture of aluminum by Toth process.