DESCRIPTION
Chemical element, atomic number Z=25. It is one of the transition metals of the first long period of the periodic table; it lies between chromium and iron. It has properties in common with both metals. Although little known or used in its pure form, it is of great practical importance in steelmaking. It is the twelfth most abundant element in the earth’s crust and is widely distributed.
It is found in hundreds of minerals, but only about a dozen are of industrial interest. They include: pyrolusite (MnO2), psilomelane (MnO2-H2O), manganite (MnO(OH)), braunite (3Mn2O3-MnSiO3), rhodonite (MnSiO3), rhodochrosite (MnCO3), hübnerite (MnWO4), etc.
The countries with the largest deposits of manganese ores are South Africa, Ukraine, Bolivia and China. The metal is obtained by reduction of the oxides with aluminum, and ferromanganese is also obtained by carbothermal reduction of iron and manganese oxides.
PROPERTIES
Manganese is a fairly reactive metal. Although the solid metal reacts slowly, the metal powder reacts readily and, in some cases, very vigorously. When heated in the presence of air or oxygen, powdered manganese forms a red oxide, Mn3O4. With water at room temperature, hydrogen and manganese(II) hydroxide, Mn(OH)2, are formed. In the case of acids, and because manganese is a reactive metal, hydrogen is released and a manganese(II) salt is formed. Manganese reacts at elevated temperatures with halogens, sulfur, nitrogen, carbon, silicon, phosphorus and boron.
Manganese oxidizes readily in air to form a brown layer of oxide. It also does so at elevated temperatures. In this respect its behavior is very similar to its higher atomic number neighbor iron.
Metallic manganese is neither classified as a hazardous substance in the EU nor as dangerous goods for transport.
APPLICATIONS
- Manufacture of steels.
- Stainless steels.
- Alloying agent in certain aluminum alloys.
- Manufacture of batteries as manganese dioxide.
