Contents
At present the most manufacturing technique of poly-aluminum chloride PAC classified as 4 according to the raw materials: Metal aluminum, Active Hydroxide method, Aluminum Oxide Method, Aluminum Chloride Method.
Metal aluminum method
The main raw materials are Aluminum wastes, like aluminum scrap, aluminum ash and aluminum dregs. Add hydroelectric acid into aluminum ash, slowing stirring the mixture for the reacting. After polymerization and precipitation, the PAC liquid made. Then the PAC powder produced by diluting, filtering and concentrating the PAC liquid.
The quality is hard to control and to cost is too high.
Aluminum oxide method
The main raw materials are gibbsite, bauxite, kaolin, coal gangue etc. The producing process can be divided into two steps: the first step is obtaining crystalline aluminum chloride, the second step is obtaining polyaluminum chloride by pyrolysising or neutralizing the crystalline aluminum chloride.
Alkali solution method
Obtain the sodium aluminate solution by mixing and reacting the aluminum ash and sodium hydroxide. Then adjust the pH Value by adding hydroelectric acid, the aluminum chloride solution made. The advantage of this method are: low insoluble content and good looking of the product color. However, the content of sodium chloride is too high; costing too much raw materials and the content of polyaluminum chloride is very low. At present the cost is too high for industrial producing.
Aluminum chloride method
The raw material is aluminum chloride. Using crystalline aluminum chloride in boiling pyrolysis at 170 ℃, and then the polymerized by water aging, and dried.
Aluminum hydroxide method
The purity of aluminum hydroxide powder is relatively high. Heating and pressuring the mixture of aluminum hydroxide powder and hydrochloric acid, the poly-aluminum chloride made. However at this time the basicity is low, so must adding the calcium aluminate powder for neutralization.
The process is simple, so the product quality is easy to control. Because of the high purity of the raw materials, the insoluble content in final product and pollution during the whole process is very low.
The picture of poly aluminum chloride producing process was taken from poly aluminum chloride manufacturer – Xunyu Group, the manufacturing technique is Aluminum hydroxide method. The raw material and whole process is very clear in the picture.