BAUXİTE ORE

Although they have different compounds, bauxite ores are used in the production of aluminum metal. Bauxite (Al2O3.nH2O) is the general name given to the minerals and aluminum ores composed of minerals rather than a mineral. The ore was named in 1821 because M. Pierre Berthier was located in the town of "Le Baux" near Arles in Southern France. 

According to their mineralogical composition, bauxites, the raw material source of primary aluminum production, are collected in 3 main groups: Gibsitic (Al2O3.3H2O) [Al (OH) 3] bauxites, bohmitic (Al2O3.H2O) [AlO (OH)] bauxites and diasporitic (Al2O3.H2O) [AlO (OH)]. Depending on the type and proportions of the iron minerals they contain; They can be in many different colors such as coffee, red, pink, light yellow, dirty yellow, beige, gray and variegated. 

Their physical and petrographic appearance is quite different. Besides the earthy and dirty look, there are also massive, quite hard and bright ones.

The production of bauxite ore is usually done by open pit mines. 

Al2O3 grade of the commercially operated bauxite ore ranges between 30-65%, 85% of bauxite obtained is for primary aluminum production. 

In the vast majority of the facilities where alumina production, which is the second stage of primary aluminum production, the bauxite processed must contain at least 40% Al2O3, at most 15% SiO2, in other words, the silica module (Al2O3 / SiO2) must be at least 7. 

Based on the chemical and mineralogical components of bauxite used in primary aluminum production, 2 tons of alumina is obtained from 4-5 tons of bauxite and approximately 1 ton of aluminum is obtained from 2 tons of alumina. 

Bauxites According to Minerological Structures 

Gibsitic Bauxites (Trihydratic): It is formed by low temperature decomposition of feldspar and corundum in blasted rocks. 

Böhmitic Bauxites (Monohydratic): They emerged as an intermediate product during the dehydration of Gibsit. 

Diasporitic Bauxites (Monohydratic): They are suggested to be formed at high temperatures. 

 Bauxites According to Formation Styles 

Silicate Bauxites: They are formed by the abrasion and washing of silicate rocks rich in aluminum. For this, rainy and warm, tropical climates, rocks with permeability and tectonic stability are the most suitable environments. Washing other elements with surface currents provides enrichment in aluminum. 

Karstic Bauxites: They are formed in the karstic cavities of limestone and dolomites. Acidic surface waters, which dissolve aluminum in other environments, are neutralized in limestones and enriched with aluminum.