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Alumina
Bauxite is a stable aluminium oxide that is used in ceramics, material science and mining. The rapid development of the country’s industries such as electrolytic aluminium, ceramics, electronics, medicine and machinery will increase the demand for alumina.
There are many ways to extract alumina from ore. These include the Bayer method and other methods such as soda-lime sintering. The Bayer Process was the primary method of producing aluminum, accounting for approximately 95% the total world alumina output. Although the acid method made huge progress in the 1970s it was not used by industry.
Bayer Process: A new way to produce alumina
The Austrian Bayer K.J. Bayer invented it in 1888. The principle is that caustic (NaOH), a solution of sodium hydroxide, is used to warm alumina and dissolve it in bauxite. This produces sodium aluminate. After the solution (red mud) is separated, the temperature of the mixture is lowered and aluminum hydroxide added as a crystal seed. After long stirring, the sodium-aluminate solution is separated to aluminum hydroxide. Then, it’s washed off and calcined in a 9501200 degree temperature range. The alumina is obtained. Mother liquor is the solution that remains after precipitation.
Because gibbsite and diaspore are different in their crystalline structure, they will dissolve at different temperatures. The gibbsite-type bauxite dissolves at 125140°C, and diaspore-type bauxite at 240260°C with the addition of lime (37%).
Bayer process alumina: advantages and disadvantages
The Bayer Process is a modern process that has achieved major progress.
1. Equipment of a large scale and continuous operation
2. Automating production processes;
3. Energy-saving techniques such as fluidized roasting, high-pressure enhanced disolution and high pressure enhanced dissolution;
4. Dry purification of flue gases and aluminum electrolysis is needed for production of sandy alumina. Bayer’s advantages
The economic effect of the Bayer Process is determined by the quality of the bauxite, mainly the SiO2 content in the ore, which is usually expressed by the aluminum-silicon ratio of the ore, that is, the weight ratio of the Al2O3 to the SiO2 content in the ore. Because in the dissolution process of the Bayer Process, SiO2 is transformed into sodalite-type hydrated sodium aluminosilicate (Na2O*Al2O3*1.7SiO2*nH2O), which is discharged along with the red mud. The Bayer Process will generate about 1 kg of Al2O3 for every kilogram of SiO2 present in the ore. This is followed by 0.8 kg of NaOH. The Bayer process has a worse economic impact the lower the aluminum-silicon bauxite ratio. Until the mid-1970s, the Bayer Process produced bauxite with an aluminum-silicon ratio greater than 7. In order to make the most of the diminishing resources of high grade gibbsite bauxite, research and development has focused on finding new ways to save energy and using other types of low quality bauxite.
(aka. Technology Co. Ltd., a global chemical material manufacturer and supplier with over 12 year’s experience in providing high-quality nanomaterials and chemicals. The Aluminum Oxide The products produced by our company are high in purity, have fine particles and low impurity levels. Contact us if you have any questions.
There are many ways to extract alumina from ore. These include the Bayer method and other methods such as soda-lime sintering. The Bayer Process was the primary method of producing aluminum, accounting for approximately 95% the total world alumina output. Although the acid method made huge progress in the 1970s it was not used by industry.
Bayer Process: A new way to produce alumina
The Austrian Bayer K.J. Bayer invented it in 1888. The principle is that caustic (NaOH), a solution of sodium hydroxide, is used to warm alumina and dissolve it in bauxite. This produces sodium aluminate. After the solution (red mud) is separated, the temperature of the mixture is lowered and aluminum hydroxide added as a crystal seed. After long stirring, the sodium-aluminate solution is separated to aluminum hydroxide. Then, it’s washed off and calcined in a 9501200 degree temperature range. The alumina is obtained. Mother liquor is the solution that remains after precipitation.
Because gibbsite and diaspore are different in their crystalline structure, they will dissolve at different temperatures. The gibbsite-type bauxite dissolves at 125140°C, and diaspore-type bauxite at 240260°C with the addition of lime (37%).
Bayer process alumina: advantages and disadvantages
The Bayer Process is a modern process that has achieved major progress.
1. Equipment of a large scale and continuous operation
2. Automating production processes;
3. Energy-saving techniques such as fluidized roasting, high-pressure enhanced disolution and high pressure enhanced dissolution;
4. Dry purification of flue gases and aluminum electrolysis is needed for production of sandy alumina. Bayer’s advantages
The economic effect of the Bayer Process is determined by the quality of the bauxite, mainly the SiO2 content in the ore, which is usually expressed by the aluminum-silicon ratio of the ore, that is, the weight ratio of the Al2O3 to the SiO2 content in the ore. Because in the dissolution process of the Bayer Process, SiO2 is transformed into sodalite-type hydrated sodium aluminosilicate (Na2O*Al2O3*1.7SiO2*nH2O), which is discharged along with the red mud. The Bayer Process will generate about 1 kg of Al2O3 for every kilogram of SiO2 present in the ore. This is followed by 0.8 kg of NaOH. The Bayer process has a worse economic impact the lower the aluminum-silicon bauxite ratio. Until the mid-1970s, the Bayer Process produced bauxite with an aluminum-silicon ratio greater than 7. In order to make the most of the diminishing resources of high grade gibbsite bauxite, research and development has focused on finding new ways to save energy and using other types of low quality bauxite.
(aka. Technology Co. Ltd., a global chemical material manufacturer and supplier with over 12 year’s experience in providing high-quality nanomaterials and chemicals. The Aluminum Oxide The products produced by our company are high in purity, have fine particles and low impurity levels. Contact us if you have any questions.