Aluminium
History
The term, aluminium, is derived from the Roman language - alumen (alum). In 1746 a German scientist named J.H.Porter obtained alumina with alum. In 1807 a British called H. David tried to get metal by electrolyzing fused alumina. In the following year, David named the expected metal alumium, later changed to aluminium. In 1825, a Danish scientist named H.C. Oersted obtained a few milligrams of aluminium by reducing anhydrous aluminium chloride with potassium amalgam.
In 1827, F. Wohler, a German scientist, got a small amount of aluminium by reducing alumina with potassium. In 1854, S.C. Deville, a French scientist, extracted aluminium by reducing NaAlCl4 with sodium and salt, and set up a factory to produce helmets, cutlery and toys, which were highly priced and as expensive as those made of gold. In 1886 Hall (U.S.) and Heroult (French) came up with the Hall-Héroult process. In 1888, the first aluminium smelter was established in Pittsburgh, signaling a new phase for aluminium production. In 1956, the worldwide aluminium output exceeded that of copper, becoming the largest in the non-ferrous metal family.
Properties & Nature
The standard electrode potential (25℃) of aluminium is -1.662V, and its electro equivalent is 0.3356 G / (An·pm). The physical properties of 99.99% aluminium are as followings:
• Density: 2.70g/cm3;
• Melting point: 660.1℃
• Boiling point: 2520℃
• Average specific heat: (0～100℃) 917J/kg·K
• Fusion heat: 10.47kJ/mol
• Vaporization heat: 291.4 kJ / mol (estimated value)
• Thermal conductivity: 238W/(m·K)
• Electricresistivity: 2.67μΩ/cm
Deposits & Resources
On average, about 7.47% of the earth's crust is aluminium, which ranks third after oxygen and silicon. There are about 25 billion tons of identified industrial reserves of aluminium bauxite in the world. If we add the amount of prospective reserves, the total amount of aluminium bauxite reserves is about 35 billion tons. Countries with rich aluminium reserves and large output include Guinea, Australia, Brazil, Jamaica, India, etc. The aluminium bauxite reserves in those countries are mostly high-iron, low-silicon gibbsite-type that are suited for simple Bayer process for the production of alumina. The proved reserves of aluminium bauxite in China are mainly found in Henan, Shanxi, Guizhou, Shandong, Guangxi provinces, etc. Except in a few areas, most of these deposits belong to diaspore type with low iron and high aluminium. There are also abundant alunite reserves in China. There are hundreds of millions of tons of kalunite in Zhejian and Anhui provinces, a raw material for alumina and potash fertilizers. In addition, large nepheline deposits are also found in Yunnan province.
