Historical
Facts and Elements Uses:
In 1774, Manganese was first isolated when the mineral pyrolusite,
MnO2, was fired in a charcoal container. When the oven cooled, a
small amount of grayish manganese was produced. Manganese ore was
first confused with magnetic iron ore. The most common oxide and
mineral is pyrolusite. Mines in the Soviet Union, India, and South
Africa produce ores containing as much as 40% manganese. Another
promising source of manganese is the "nodules" that are scattered over
large portions
of the ocean floor. These chunks which vary from a few millimeters
to a few meters in diameter, consist mainly of manganese and iron oxides.
Billions of tons are present, but mining them presents major technical
and political challenges. Cooperation will be required to mine the
nodules such that the rewards will be shared globally. Elemental
manganese is hard and shiny. Like vanadium and chromium, it is used mostly
to make steel alloys. A small amount of manganese (< 1%) makes
steel easier to roll, forge, and weld. It also increases the resistance
of steel to impact. The steel used in railroad tracks contain as
much as 1.2 % manganese. Steel made with 12 % manganese is tough
enough to be used for naval armor and bulldozer blades.
Small amounts of manganese are added to aluminum beverage cans and
bronze alloys to make them stiffer and tougher.
Manganese exhibits many oxidation states. All manganese species
with oxidation states greater than +2 act as oxidizing agents. The
purple permanganate ion, KMnO4- ion is particularly powerful. Other
uses of manganese include:
manganese (IV) oxide, MnO2, in dry cell and alkaline batteries,
permanganic acid, HMnO4, which is as strong as perchloric acid. It
has a biological role of activating many enzymes. It is crucial to
the effectiveness of vitamin B1. Without
manganese, bones grow spongier and break more easily. |
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