Important uses of Bauxite: An Introduction
Aluminium is an extremely versatile metal that has a wide range of applications in our daily life and in various industries. It is very flexible and lightweight. Aluminium is the third most abundant element in the earth's crust also. But aluminium is not found independently on the earth's crust. It is extracted from the corresponding ore. The major source of aluminium is its ore bauxite hence the main use of bauxite is to produce aluminium mainly by the process of leaching. It is a sedimentary rock formed by the chemical weathering of tropical climate; the leaching of silica in aluminium-bearing rocks. Bauxite appears dull in lustre and is reddish brown, white or tan in colour. The molecular formula of bauxite is Al2H2O4. There are two types of bauxite, calcined bauxite and laterite bauxite.
Chemical Composition of Bauxite
Bauxite does not have a specific composition. It is a mixture of hydrous aluminium oxides, aluminium hydroxides, clay minerals, and insoluble materials such as quartz, hematite, magnetite, siderite, and goethite. The aluminium minerals in bauxite can include gibbsite Al(OH)3, boehmite AlO(OH), and diaspore, AlO(OH).
Physical Properties of Bauxite
Bauxite appears dull in lustre and is reddish brown, white or tan in colour. The Mohs hardness of bauxite is 1 to 3, which means it is a very soft material. The specific gravity is around 2 to 2.5. Bauxite is always processed into other materials with physical properties that are extremely different from bauxite.
What are the Uses of Bauxite?
Bauxite has a multipurpose use in various industries. The uses of bauxite are listed below
In Metallurgy
Bauxite is the best and only material used for the production of aluminium. Aluminium production is the main use of bauxite. Once aluminium is extracted, it finds many applications in electronics, constructions, vehicles and in utensils.
The conventional steps of production of aluminium are Bayer’s process, where bauxite is converted to alumina and through the hall heroult process, aluminium produces. In the above process, 4 to 5 tonnes of dried bauxite gives 2 tonnes of alumina, and it again gives almost one ton of aluminium.
In Chemical Industry
Production of aluminium chemicals like aluminium sulphate, aluminium chloride, aluminium fluoride, sodium aluminate etc is an important use of bauxite. Bauxite is directly used to produce aluminium sulphate, which is a flocculating agent in water and effluent. Anhydrous AlCl3.6H2O is used as a catalyst in organic reactions and has metallurgical and metal finishing applications. Aluminium fluorides are used as a flux in remelting aluminium and aluminium alloys. Sodium aluminate is used for industrial water treatment.
In Refractory Industry
Bauxite is used as raw material in making refractory products since it has a melting point from 1740 to 18200C. The principal use for the refractory grade bauxite is in the production of alumina refractories containing 75 to 90% of alumina; these are used in the manufacture of bricks to lane the roof of blast furnaces and electrical and steel-making furnaces. In the copper industry, high alumina refractories are used in reverberatory furnaces. Also, the glass and cement industry uses high alumina refractories.
In Abrasive Industry
Bauxite is used in abrasive industries. The abrasive grain is produced either by the fusion of chemically purified alumina or from calcined bauxite. The product from the fused calcined bauxite is called brown fused alumina. The brown fused alumina accounts for 80 to 90% of fused alumina in the abrasive industry. It has application in bonded and coated abrasives such as grinding wheels, belt sheets and mops. The fused alumina is used to grind high-strength materials like bronze and steel.
In Cement Industry
The high alumina cement is obtained by mixing selected qualities of bauxite with limestone. These cements are known for their quality and rapid setting time. The high alumina cement sets within 3 to 4 hours and becomes strong after 24 hours. It is resistant to corrosion and resistant to sulphate and dilutes acids present in the soil, so high alumina cement is used to make tunnels, concrete piles etc.
In Absorbant Industry
Activated bauxite is used as a drying agent for gases and organic liquids hence it is suitable to use in the petroleum industry. It is used as an absorbent for a number of compounds based on sulphur and fluorine. It also has applications in the areas of catalyst and filtration.
In Steel Industry
In the steel, industry, bauxite is used to control desulphurising power and fluidity of the slag and provide material for blast furnaces of the cement during iron making. It is also used in oxygen furnaces as an additive to control the viscosity of the slag. Here bauxite is used as a source of alumina to control viscosity.
In Building Stone and Road Aggregates
Laterite bauxite is a handy substitute for building materials if no other materials are available. Calcined bauxite is used as anti-skid road aggregate, which can be used in selected locations to prevent road accidents. Using of calcined bauxite in roads hence considered as an important uses of bauxite
Other Uses
Bauxite is also used in so many other industries like rubber, plastic, cosmetics and paint industry as filler. Calcined bauxite is used as welding flux composition in submerged arc buildings. These are the common uses of bauxite
Uses of Alumina in Daily Life.
Bauxite is also having a wide role in our daily life also. Because aluminium is a metal that is important in our daily life. The daily uses of bauxite includes use of alumina in beverage cans, dye stuffs, ceramic products, heat resistant bricks etc.
Key Features
Bauxite is the best and only source of aluminium production
In metallurgy, bauxite is mainly used to produce aluminium through Bayer's process and hall heroult process
Calcined bauxite is used as anti-skid particle in road
In the steel industry, it is used to control desulphurising power.
The common uses of bauxite includes usage of it in rubber, plastic,steel and paint industry as a filler
Conclusion
Bauxite is a sedimentary rock which is the prime source of aluminium and gallium. The chemical formula of bauxite is Al2H2CO4, and it is a soft material. It has a wide range of applications in various fields like the cement and steel industry, metallurgy, refractories etc.
FAQs on What are the Main Uses Of Bauxite: A Detailed Summary
1. What exactly is bauxite and what is its chemical makeup?
Bauxite is a naturally occurring sedimentary rock that is the world's main source of aluminium. It is not a specific mineral but a mixture of hydrated aluminium oxides. Its general chemical formula is often given as Al₂O₃·nH₂O, but it primarily consists of minerals like gibbsite (Al(OH)₃), böhmite (γ-AlO(OH)), and diaspore (α-AlO(OH)), along with impurities like iron oxides and silica.
2. What are the main industrial uses of bauxite?
The vast majority of bauxite (about 85-90%) is used to produce alumina (Al₂O₃), which is then refined to create aluminium metal. However, it also has important non-metallurgical uses.
- Abrasives: Calcined bauxite is very hard and used in grinding and polishing materials.
- Refractory Materials: It is used to make high-temperature materials like firebricks for furnaces.
- Chemicals: Used to manufacture aluminium chemicals like aluminium sulfate.
- Cement: Added during cement production to increase its strength and setting time.
3. How is pure aluminium obtained from bauxite?
Obtaining aluminium from bauxite is a two-step process. First, the bauxite ore is purified using the Bayer process to produce alumina (aluminium oxide). In the second step, this alumina is subjected to the Hall-Héroult process, where it is dissolved in molten cryolite and electrolysed to produce pure aluminium metal.
4. Why is bauxite preferred over other minerals for aluminium extraction?
Although aluminium is the most abundant metal in the Earth's crust, it is usually found in complex silicate minerals like clays and feldspars. Extracting aluminium from these silicates is extremely difficult and expensive. Bauxite, on the other hand, contains aluminium in the form of oxides, from which it can be extracted much more economically using the established Bayer and Hall-Héroult processes.
5. What is the difference between bauxite and alumina?
Bauxite is the raw, naturally occurring ore that is mined from the ground. It is a mixture of various minerals. Alumina (aluminium oxide, Al₂O₃) is the intermediate product obtained after bauxite has been chemically processed and purified. Alumina is a white powder that is then used to produce aluminium metal.
6. What are some examples of bauxite's use in everyday products?
You can find the end-products of bauxite all around you. The aluminium from bauxite is used in:
- Transportation (cars, airplanes, ships)
- Packaging (beverage cans, aluminium foil)
- Construction (window frames, building facades)
- Electronics (smartphones, laptops)
7. What is 'red mud' and why is it a concern in bauxite processing?
Red mud is the primary waste product generated during the Bayer process when refining bauxite into alumina. It is a highly alkaline slurry containing iron oxides (which give it the red colour) and other impurities from the original ore. Its high alkalinity and large volume make its storage and disposal a significant environmental challenge for the aluminium industry.
