The physicochemical properties and preparation method of aluminum sulfate

[Physical and chemical properties] Anhydrous aluminum sulfate is a colorless crystal (orrhombic crystal system), hydrated aluminum sulfate can contain 6, 10, 16, 18 or 27 crystal water molecules, and octahydrate is more at room temperature.

[Preparation]

Preparation method 1 Bauxite sulfuric acid reaction method

The main components of bauxite are Al2O3 and SiO2

Al2O3+3H2SO4→Al2(SO4)3+3H2O

When the aluminum oxide is excessive, basic aluminum sulfate is generated, and the reaction is as follows:

Al2O3+2H2SO4→2Al2(OH)SO4+H2O

Basic aluminum sulfate can be neutralized by sulfuric acid to produce aluminum sulfate

2AI(OH)SO4+H2SO4→Al2(SO4)3+2H2O

Aluminium: There are three methods for preparing aluminum sulfate by the sulfuric acid reaction method of earth ore.

Figure 2-1 Process flow of aluminum sulfate produced by bauxite pressure reaction method

Preparation method 2 aluminum hydroxide sulfuric acid reaction method

Aluminum hydroxide reacts with sulfuric acid, the reaction solution is settled, concentrated, cooled and solidified, crushed and sieved to obtain finished aluminum sulfate

3H2SO4+2AI(OH)3→Al2(SO4)3+6H2O

Preparation method 3 Alunite method

The alumite is calcined, pulverized and dissolved with dilute sulfuric acid, filtered to remove insolubles to obtain a mixed solution of aluminum sulfate and potassium alum, rapidly cooled and crystallized to remove the potassium alum, concentrated the mother liquor, and cooled and processed into flakes

Preparation method 4 Kaolin method

The kaolin is calcined and crushed to a certain particle size at 700～800℃, reacts with a certain concentration of sulfuric acid in a batch cooking reaction tank at 105～110℃ for 5h, and then the reaction slurry is fed into the slurry storage tank for the continuity of the subsequent production process.

Preparation method 5 Fly ash method

Using fly ash, a waste discharged from the power plant, as a raw material, 60% sulfuric acid and fly ash are reacted at 100°C for 6 hours, and an iron-containing aluminum sulfate solution is filtered

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