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Mn, A. Jonathan Buhalis
MANGANESE
by Jonathan Buhalis

History

Two metals with similar names are magnesium and manganese. These originate in ancient times with two minerals from the region of Magnesia in Thessaly, Greece. One mineral, called magnesia alba by medieval alchemists, was eventually found to contain magnesium. The other metal was called magnesia negra. Medieval glassmakers called it manganesum (note the two "n"s), later contracted to manganesa. (Yet a third mineral from Magnesia, magnetite, gives us the word magnet.)

By the middle of the 18th century, manganesa (which we know as manganese dioxide) and other manganese compounds had been used for centuries in glassblowing, for either coloring or decoloring glass. Many new elements were discovered in this era, and as part of that effort, manganesa was identified as the compound of an unknown metal. Swedish Chemist Johan Gottlieb Gahn reduced the oxide to a metal in 1774.

The current main application of manganese, hardening steel, was discovered forty years later, but wasn't put into practice on any significant scale until greater advancements in metallurgy toward the end of the 19th century. When Henry Bessemer developed his revolutionary method of inexpensive steel production around 1860, it was a small amount of added magnesium that made the process possible.

Mining and Production

Manganese is a hard brittle metal. It is mined in many countries, particularly South Africa and Australia, as a variety of ores.

Ores of manganese are typically reduced with coke (charcoal) and then purified by electroplating. Because almost all manganese is destined to be alloyed with steel, it is normally sold and transported as ferromagnesium, a steel alloy bearing excess amounts of the metal.

Properties and Uses

Fully 85% or more of manganese goes into steelmaking. About a third of this is used to remove undesirable sulfur from crude steel. The balance is as an alloying component to harden steel. Most steel contains some manganese, from 1% to 15% or more, depending on the required hardness.

Manganese is also used as an alloy with aluminum to resist corrosion. Most commercial aluminum containers (i.e., beverage cans) contain around 1.5% manganese.

Manganese dioxide is used in electrodes in dry cell batteries. Potassium permanganate (below), recognized by its distinctive purple crystals, is a reactive salt used to purify water and eliminate strong odors in industrial areas.

potassium permanganate crystals, A. Jonathan Buhalis
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Content by Jonathan Buhalis
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