Bauxite is a mixture of aluminum oxide and hydroxides with a hardness of 1-3 and a density of 2.5-3.5 g/cm3. Bauxite ore is not a mineral with a homogeneous chemical composition and crystal structure, but a heterogeneous mixture of these minerals. Bauxite consists of a mixture of 4 different chemical minerals: diasporite (Al2O3.H2O), boehmite [AlO (OH)], gibbsite (hydrargillite) Al2O3.3H2O and Corundum (Al2O3). Bauxite generally contains Iron Oxide (Fe2O3), Silicon Oxide (SiO2) and Titanium Oxide (TiO2). 90% of the metal aluminum production in the world is provided from this Bauxite ore. Bauxite has a light colored earthy appearance. However, its color is usually reddish-brown due to its iron content. It is the only mineral group that can produce aluminum. Aluminum (Al) is a silver-colored light metal with atomic no. 13 and a density of 2.70 g/cm³. Aluminum, which is the most abundant element in the earth after oxygen and silicon, is not found pure in nature, it is present as oxide and silicate compounds. It constitutes 8% of the earth bedrock.
Aluminum, which is in the light metal class, is an element with high electrical and thermal conductivity, light and soft, easy to process, corrosion resistant, cold and hot forming, and has a very wide area of use in the industry. Aluminum is an exceptionally conductive metal and much lighter than copper. Generally, from four units of bauxite to two units of alumina, one unit aluminum is produced. Aluminum production takes place in 2 stages. With Bayer process, fine grinded bauxite ore is put under radiation to change Aluminum to Sodium Aluminate in it, then it is turned to Aluminum Oxide (Alumina) by being calcined in high temperature with aluminum hydroxide (Hydrate) extraction. Aluminum is obtained from Alumina by electrolysis method.
With new technologies, 13,000 Kws/t of energy is required to obtain 1 ton of aluminum. The most important cost of the conversion process from bauxite ore to aluminum is the energy requirement which is 40%.