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Alumina
Bauxite is a stable aluminium oxide that is used in ceramics, material science and mining. The rapid development of our country’s electrolytic aluminium, ceramics industries, medicine, electronics and machinery will increase the demand for alumina.
There are several ways to extract alumina from ores, including the Bayer method and combined Bayer/sintering methods. The Bayer Process was the primary method for producing aluminum, with its output accounting for approximately 95% of total global 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. It works by using caustic (NaOH, or sodium hydroxide) solution to warm up and dissolve alumina within 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 temperature range of 950-1200. The alumina is obtained. Mother liquor is the solution that remains after precipitation.
Because gibbsite and boehmite are different in their crystalline structure, they will dissolve at different temperatures. The gibbsite-type bauxite dissolves at 125140°C, while the diaspore-type bauxite dissolves at 240260°C with lime (37%).
Bayer Process Alumina Products: Benefits
The Bayer Process is a modern process that has made major progresses in:
1. Equipment of large scale and continuous operation
2. Automation of production processes;
3. Using fluidized roasting, high-pressure enhanced disolution or other energy-saving techniques such as 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 effect the lower the aluminum-silicon ration of bauxite. Up until the late 70s, the Bayer Process used bauxite with an aluminum-silicon concentration greater than 7. In order to make the most of the diminishing resources of gibbsite type bauxite, research and development has focused on finding new ways to save energy and using other low-grade types of bauxite.
(aka. Technology Co. Ltd., a trusted global chemical supplier & manufacturer has over 12 years experience in providing super-high-quality chemicals and nanomaterials. The Aluminum Oxide The products produced by our company are high in purity, have fine particles and contain low impurities. Contact us if you have any questions.
There are several ways to extract alumina from ores, including the Bayer method and combined Bayer/sintering methods. The Bayer Process was the primary method for producing aluminum, with its output accounting for approximately 95% of total global 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. It works by using caustic (NaOH, or sodium hydroxide) solution to warm up and dissolve alumina within 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 temperature range of 950-1200. The alumina is obtained. Mother liquor is the solution that remains after precipitation.
Because gibbsite and boehmite are different in their crystalline structure, they will dissolve at different temperatures. The gibbsite-type bauxite dissolves at 125140°C, while the diaspore-type bauxite dissolves at 240260°C with lime (37%).
Bayer Process Alumina Products: Benefits
The Bayer Process is a modern process that has made major progresses in:
1. Equipment of large scale and continuous operation
2. Automation of production processes;
3. Using fluidized roasting, high-pressure enhanced disolution or other energy-saving techniques such as 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 effect the lower the aluminum-silicon ration of bauxite. Up until the late 70s, the Bayer Process used bauxite with an aluminum-silicon concentration greater than 7. In order to make the most of the diminishing resources of gibbsite type bauxite, research and development has focused on finding new ways to save energy and using other low-grade types of bauxite.
(aka. Technology Co. Ltd., a trusted global chemical supplier & manufacturer has over 12 years experience in providing super-high-quality chemicals and nanomaterials. The Aluminum Oxide The products produced by our company are high in purity, have fine particles and contain low impurities. Contact us if you have any questions.