Current Location： Home > News > Chemical Knowledge > Manufacturing method and process flow of alumina

[Chemical Knowledge]：Manufacturing method and process flow of alumina

Read： 897 Time：13months ago Source：Transform the World with Simplicity

The manufacturing method
of alumina
1. Introduction

alumina is an important raw material for chemical production, widely used in ceramics, electronics, metallurgy and other fields. Therefore, it is of great significance to study the manufacturing method of alumina for improving production efficiency, reducing costs and improving product quality. This article will introduce several common alumina manufacturing methods.

2. aluminum hydroxide method

aluminum hydroxide method is one of the most commonly used methods in alumina production. The principle of this method is that alumina in bauxite is converted into aluminum hydroxide by chemical reaction, and then calcined to obtain alumina. The specific steps are as follows:

1. Dissolution of bauxite: bauxite is mixed with sodium hydroxide solution to convert alumina into sodium aluminate.

2. Separation: The sodium aluminate solution is separated from the impurities by filtration, washing, etc.

3. acidification: adding acidifying agent such as sulfuric acid or hydrochloric acid to sodium aluminate solution to convert sodium aluminate into aluminum hydroxide precipitate.

4. Filtration, washing: The aluminum hydroxide precipitate is separated from the mother liquor and washed until neutral.

5. Calcination: Aluminum hydroxide is calcined at high temperature to obtain alumina product.

aluminum hydroxide method has the advantages of simple process, convenient operation and stable product quality, so it is widely used in alumina production.

3. Bayer process

The Bayer process is an important method in alumina production and is suitable for the treatment of high-grade bauxite. The principle of the method is to use sodium hydroxide solution to dissolve alumina in bauxite under high temperature and high pressure to obtain sodium aluminate solution, and then obtain aluminum hydroxide through cooling, crystallization, separation and other steps, and finally calcine to obtain alumina. The specific steps are as follows:

1. batching: mix bauxite, sodium hydroxide and circulating mother liquor according to a certain proportion to make raw pulp.

2. high pressure dissolution: the original pulp is dissolved under high temperature and high pressure to obtain sodium aluminate solution.

3. dilution, cooling: the sodium aluminate solution dilution, cooling, so that aluminum hydroxide precipitation.

4. Separation, washing: The aluminum hydroxide is separated from the mother liquor by filtration, washing, etc., and washed to neutrality.

5. Calcination: Aluminum hydroxide is calcined at high temperature to obtain alumina product.

Bayer process has the advantages of short process, low energy consumption and high product quality, but the equipment investment is large and it is suitable for large-scale production.

4. sintering method

sintering method is a traditional method in alumina production, which is suitable for processing low-grade bauxite. The principle of the method is that raw materials such as bauxite, sodium hydroxide and lime are mixed and sintered to obtain clinker, and then dilute alkali solution is used to dissolve alumina in the clinker to obtain sodium aluminate solution, and finally alumina is obtained through crystallization, separation, calcination and other steps. The specific steps are as follows:

1. ingredients: bauxite, sodium hydroxide and lime and other raw materials are mixed according to a certain proportion.

2. Sintering: The mixture is sintered at high temperature in a rotary kiln to obtain clinker.

3. Dissolution: The clinker is mixed and dissolved with dilute alkali solution to obtain sodium aluminate solution.

4. Crystallization and separation: aluminum hydroxide is precipitated and separated from the mother liquor through steps such as cooling and crystallization.

5. Calcination: Aluminum hydroxide is calcined at high temperature to obtain alumina product.

sintering method has the advantages of strong adaptability of raw materials and stable product quality, but the process is longer and the energy consumption is higher.

5. Conclusion

Three common alumina manufacturing methods, such as aluminum hydroxide method, Bayer method and sintering method, are introduced above. Different methods have different advantages and disadvantages and scope of application, and the appropriate production method should be selected according to the actual situation. At the same time, with the continuous progress of science and technology, the manufacturing technology of alumina is also constantly improving, and more new technologies and new methods will be applied to alumina production in the future.

Previous： Production and manufacturing method and process flow of copper oxide

Next： Manufacturing method and process of silicon dioxide

News Categories