Manganese & compounds: Overview
Description
Manganese is predominantly used to produce ferromanganese, or metallic manganese, which is used in the production of steel to improve hardness, stiffness, and strength. It is used in carbon steel, stainless steel, high-temperature steel, and tool steel, along with cast iron and superalloys. Manganese finds further applications in a number of non-ferrous alloys, especially with aluminium, magnesium, copper and zinc.
Applications for various manganese compounds follow.
- Manganese dioxide is commonly used in the production of batteries, matches, fireworks, porcelain, glass-bonding materials and amethyst glass, as the starting material for production of other manganese compounds, and as an oxidising agent.
- Manganese chloride is used as a precursor for other manganese compounds, as a catalyst in the chlorination of organic compounds, as dietary supplement/food additive, in animal feed to supply essential trace minerals, in paint driers, fertilisers, in dyeing, disinfecting, purifying natural gas, and in dry-cell batteries.
- Manganese sulfate is used in glazes, varnishes, ceramics, dyeing, fertilisers, fungicides, and ore flotation. It is also used in medicines and as a nutritional supplement.
- Potassium permanganate is used as an oxidising agent, a disinfectant, as an anti-algal agent, in metal cleaning, in tanning, bleaching, and as a preservative for fresh flowers and fruits.
- Manganese gluconate is used as a feed additive, food additive, and dietary supplement.
- Manganese oxide is used in textile printing, ceramics, paints, coloured glass, animal feeds, fertilisers, and in welding. It is used as a catalyst in the manufacture of allyl alcohol, as food additive and a dietary supplement.
- Manganese nitrate is used as a colour agent in porcelain and ceramic manufacture, as a catalyst, and in the production of manganese dioxide.
- Manganese acetate is used in textile dyeing, fertilisers, food packaging, feed additives, and in manufacturing paints and varnishes.
- Manganese carbonate is used as a pigment, drier for varnishes, in medications, and as a plant nutrient. It is used in the manufacturing of manganese salts, pharmaceuticals, animal feeds, and ceramics.
Substance details
Substance name: Manganese & compounds
CASR number: 7439-96-5
Molecular formula: Mn
Synonyms: Colloidal manganese, elemental manganese, cutaval. Manganese compounds include manganese acetate (CASR# 638-38-0), manganese carbonate (CASR# 598-62-9), manganese chloride (CASR# 7773-01-5), manganese tetroxide (CASR# 1317-35-7), manganese dioxide (CASR# 1313-13-9), potassium permanganate (CASR# 7722-64-7), manganese gluconate (CASR# 6485-39-8), manganese oxide (CASR# 1344-43-0), and manganese sulfate (CASR# 7785-87-7).
Physical properties
Manganese is a very brittle, hard metal of white-grey colour.
Atomic Number: 25
Atomic Mass: 54.9
Melting Point: 1244°C
Boiling Point: about 2000°C
Specific Gravity: 7.2 to 7.4
Manganese is very similar to iron in its physical and chemical properties, the chief difference being that manganese is harder and more brittle but less refractory. Properties vary widely depending on the particular compound.
- Manganese acetate comes in the form of brown crystals.
- Manganese carbonate is a pink-to-white hygroscopic powder with specific gravity 3.1.
- Manganese chloride comes in the form of pink cubic hygroscopic crystals with melting point 650°C and boiling point 1190°C.
- Manganese nitrate is a colourless or pink solid in crystal form.
- Manganese dioxide is a black crystalline solid or powder with melting point 535°C and specific gravity 5.0.
- Manganese gluconate comes in the form of a light pink powder or coarse pink granules.
- Manganese oxide comes in the form of green cubic crystals or green powder.
- Manganese sulfate comes in the form of reddish crystals or pale red, slightly efflorescent crystals.
- Potassium permanganate comes as dark purple crystals with blue metallic sheen. The crystals have a specific gravity of 2.7, a vapour density of 5.4 and melt at 240°C.
Chemical properties
Manganese exists mostly in the (II) oxidation state in natural compounds. It can also appear as manganese (IV) in manganese dioxide. Synthetic compounds are known in nearly all oxidation states between (III-) and (VII+). The metal decomposes in water and readily dissolves in dilute, non-oxidising acids and reacts vigorously with many non-metals at elevated temperatures. Finely divided manganese can combine explosively with a number of materials. Solubility of manganese compounds in water ranges from poorly soluble (manganese dioxide, manganese tetroxide, manganese carbonate, and manganese sulfide) to soluble (manganese sulfate, manganese chloride, manganese nitrate, permanganate ion).
- Manganese acetate is soluble in alcohol and water, and decomposes in cold water.
- Manganese carbonate decomposes before reaching its melting point. It is soluble in dilute acid, and insoluble in water, alcohol, and ammonia.
- Manganese chloride is soluble in water and alcohol, and insoluble in ether. It is deliquescent (i.e. if exposed to air, it absorbs moisture from the atmosphere to such an extent that it will dissolve).
- Manganese gluconate is soluble in water, and insoluble in alcohol and benzene.
- Manganese oxide is soluble in acids and ammonium chloride, and insoluble in water.
- Manganese sulfate is soluble in alcohol, and insoluble in ether.
- Manganese tetroxide is insoluble in water, and soluble in hydrochloric acid.
- Manganese dioxide is insoluble in water, and inert to most acids except when heated. With hot hydrochloric acid chlorine is evolved.
- Potassium permanganate is soluble in water, sulfuric acid and acetone.
Further information
The National Pollutant Inventory (NPI) holds data for all sources of manganese and compounds emissions in Australia.
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