Bauxite is the primary ore of aluminum, known as oxide or alumina. Found in the upper layer of the earth’s crust, Bauxite is formed as a result of the dissolution and physical weathering of lateritic rocks in hot and humid environments. When lateritic rocks decompose with the iron and aluminum they contain, it results in the formation of bauxite ore.
Bauxite, which does not have a homogeneous chemical composition and is also a mineral that does not have a crystal structure, is defined as a heterogeneous mixture. Physically, bauxite ore has a soil-like appearance, usually white, gray, or brown in color.
Image 1. Bauxite Ores
Bauxite Minerals
Bauxites according to their Mineralogical Structures
Minerals such as gibbsite, boehmite, diaspore, corundum can be found in mixtures in various ratios and are referred to as bauxite. These minerals are the sole mineral group that can produce aluminum, and the most significant ones with aluminum oxides and hydroxides are bauxite minerals.
| Mineral Name | Chemical Formula | Hardness | Density |
| Gibbsite/Hydrargillite | Al(OH)3 or Al2O3.3H2O | 2.5-3 | 2.4 |
| Boehmite | AlOOH or Al2O3.H2O | 3.5-4 | 3.01 |
| Diaspore | HAlO2 or Al2O3.H2O | 6-7 | 3.3-3.5 |
| Corundum | Al2O3 | 9 | 4 |
Table 1. Chemical and Physical Properties of Bauxite
Bauxite contains various aluminum minerals but the most common are gibbsite and boehmite; and aluminum metal is produced from these ores. Diaspore is not suitable for aluminum production like these ores. Corundum ore is used as an abrasive.
Image 2. Bauxite Ore
Bauxites according to Types of Formation
Silicate bauxites are formed by the weathering and washing of the rich aluminum content of silicate rocks. The most suitable condition for this type of formation is rainy and warm, tropical climates, and rocks with high permeability and tectonic stability. Washing of other elements by surface runoff enables aluminum enrichment.
Karst bauxites; acidic surface waters that have dissolved aluminum in other environments, fill into the karstic cavities of limestone and dolomites, where they neutralize and result in aluminum enrichment.
Image 3. Bauxite mining
Where to Use Bauxite
Bauxite is a soft and light material as it contains aluminum, which is classified as a light metal. Thus, it has a wide range of use thanks to its properties of easy workability, cold and hot workability, electrical and thermal conductivity, and corrosion resistance.
- Alumina Production
Due to its high alumina content, bauxite is commonly used as a primary raw material in alumina production. 90% of the world bauxite production is for the production of alumina (Al2O3) and aluminum (Al), and gibbsite and boehmite ores fulfill this requirement.
- Calcium Aluminate Cement (CAC) Production
We have already discussed what calcium aluminate cements and their contents are in our blog post titled Everything You Need To Know About Calcium Aluminate Cement! Bauxite is the primary material for the production of calcium aluminate cement. Bauxite is used as an aluminum resource and its top advantages are its lumpy form and high temperature distortion resistance.
- Alumina Resource for Portland Cement
Bauxite is used as a resource of high alumina to adjust the feed for clinker production if the alumina content is low for the formation of the necessary alumina phases during clinker sintering. Check out the link for further details on Çimsa’s Portland Cement.
- Iron-Steel Slag Optimizer Used in Blast Furnaces
The use of bauxite provides significant operational advantages in blast furnace operations while also providing cost savings.
Specially developed for high quality steel production, Duro a special product of Çimsa, is a calcium aluminate flux product whose raw material is bauxite.
Thanks to its special physical and chemical structure, Duro – Flux provides efficient refining in tundish processes, which is a continuous casting process, in secondary metallurgy.
Image 4. Çimsa Calcium Aluminate Cement Family
Click here to check out our products.
Bauxite Reserves in Turkey and the World
Bauxite deposits are generally located within 0-2 m of the surface, and strip-mining method is used in approximately 80% of bauxite deposits worldwide.
The global mineable bauxite reserves are estimated to be approximately 30 billion tons. The countries that have the richest reserves are as follows: Guinea (7,4 billion tons), Australia (6 billion tons), Vietnam (3.7 billion tons), Brazil (2.6 billion tons), Jamaika (2 billion tons), Indonesia (1 billion tons), China (1 billion tons), Guyana (0.8 billion tons), India (0.8 billion tons) and Russia (0.5 billion tons).
The mineable bauxite reserves in Türkiye are around 63 million tons. The regions with the richest reserves are as follows: Seydişehir – Akseki (31 billion tons), Muğla – Milas – Yatağan (17.5 billion tons) and Tufanbeyli – Saimbeyli (9.8 billion tons).
Image 5. Bauxite Site
Bibliography
https://www.mta.gov.tr/v3.0/metalik-madenler/boksit
Everything You Need to Know About Calcium Aluminate Cement!
What is refractory? How To Use Calcium Aluminate Cement As Refractory? – III
Eroğlu G., Şahiner M., “Dünyada ve Türkiye’de Alüminyum”
Chamber of Geological Engineers, Aluminum
