Manganese

Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery-grey metal, often found in combination with iron and other minerals. Manganese is essential for the production of steel and other alloys, and it is also used in batteries, ceramics, and fertilisers. It is the fourth most commonly used metal in the world, after iron, aluminium, and copper.

History

The discovery of manganese dates back to ancient times, with references to its use in the Roman Empire and in India. The metal was first isolated in 1774 by Johan Gottlieb Gahn, a Swedish chemist, who heated the mineral pyrolusite with carbon. The metal was named after the Latin word "magnes," which means magnet, because it was found to be attracted to magnets.

Properties

Manganese is a transition metal with several important physical and chemical properties. It is hard and brittle, with a silvery-grey appearance. It is highly reactive and readily forms compounds with other elements, such as oxygen, sulphur, and chlorine. It has a high melting point of 1,244°C (2,271°F) and a boiling point of 2,646°C (4,795°F).

Uses

Manganese is primarily used in the production of steel and other alloys. It is added to steel to improve its strength, hardness, and resistance to corrosion. It is also used in the production of batteries, such as alkaline batteries and lithium-ion batteries. Manganese dioxide is used as a pigment in ceramics, as a decolorising agent in glass, and as a catalyst in chemical reactions. Manganese sulphate is used as a fertiliser in agriculture, to improve the growth of plants.

Health Effects

Manganese is an essential nutrient for humans and animals, but it can be toxic at high levels. Inhalation of manganese dust or fumes can cause a condition known as manganism, which is similar to Parkinson's disease. Long-term exposure to high levels of manganese can also cause damage to the liver, kidneys, and nervous system. Ingestion of large amounts of manganese can cause a condition known as manganism, which is characterised by symptoms such as muscle weakness, tremors, and difficulty speaking.

Environmental Impact

Manganese is naturally present in the environment, and it is also released into the environment through human activities, such as mining, smelting, and the use of manganese-containing products. Elevated levels of manganese in drinking water can pose a health risk to humans, particularly infants and young children, who are more susceptible to the effects of manganese toxicity. Manganese contamination can also affect aquatic life, leading to the accumulation of manganese in the tissues of fish and other organisms.

Regulation and Safety

In the United States, the Occupational Safety and Health Administration (OSHA) has established a permissible exposure limit (PEL) of 5 milligrams per cubic meter (mg/m3) for manganese dust, to protect workers from the harmful effects of manganese exposure. The Environmental Protection Agency (EPA) has also established a maximum contaminant level (MCL) of 0.05 milligrams per litre (mg/L) for manganese in drinking water, to protect public health.

Production and Mining

Manganese is primarily mined in South Africa, Australia, China, and Brazil. The largest producers of manganese ore are South Africa, Australia, China, and Gabon. Manganese is extracted from its ores by crushing, washing, and magnetic separation. The resulting concentrate is then roasted to remove impurities and converted to a product called ferromanganese, which is used in the production of steel.