magnesium n. a light silvery-white metallic element of the alkaline earth series, occuring principally in magnesite, dolomite and carnallite: used in light structural alloys. Symbol: Mg; atomic no.:12; atomic wt.: 24.312; valency: 2; relative density: 1.738; melting point: 651°C; boiling pt.: 1107°C; crystal structure: close packed hexagonal (a=3.2030 c= 5.2002)
Magnesium is the lightest of the structural metals; a quarter the weight of steel and a third lighter than aluminium. This element was first isolated in 1808 by the English scientist Davy, but it was not until 1852 that Bunsen demonstrated that magnesium metal could be isolated by electrolysis of fused anhydrous magnesium chloride, magnesium being released at the cathode and chlorine at the anode of the cell.
The commercial possibilities of the electrolytic method of production were first exploited in 1909 by a German company, Chemische Fabrik Griesheim Elektron. By the 1920’s, the electrolytic process had been worked out on an industrial scale and the metal became available in commercial quantities to justify its use as a structural material.
Today, magnesium is used in a diverse range of markets and applications, each one exploiting the unique physical and mechanical properties of the element and its alloys. World production of magnesium totals around 400,000 tonnes per annum and the figure is increasing annually as the lightweight properties of magnesium alloys are used increasingly in the automotive industry as a means of reducing weight, increasing fuel efficiency and reducing greenhouse gas emissions.
To service this growing demand, there is potentially no limit to magnesium output since magnesium is the eighth most common element in the world and the sixth most abundant metal, comprising about 2.5% of the earth's surface. Seawater contains 0.14% magnesium and the element is abundant in minerals Carnallite (MgCl.KCl.6H2O), Dolomite (MgCO3.CaCO3), and Magnesite (MgCO3). Demand for magnesium is also being met by an expanding magnesium recycling industry. Alloys used for structural applications can be recycled back into products displaying the same chemical, physical and mechanical characteristics as primary material. This attribute is being actively encouraged within the industry, given its positive impact upon the environment. Recycling requires only 5% of the energy required to produce the primary product.
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