Polyaluminum Chloride, also known as PAC, is a highly effective Industrial Water Treatment Chemical. As an important inorganic polymer flocculant, PAC has excellent performance in removing suspended matter, colloid, organic matter and heavy metal ions in the water because of its high molecular weight, high charge density and fast hydrolysis rate. In the last article, we discussed the main source of PAC raw materials. Then how is it produced? In this article we will explore this issue in depth.
The Main Production Process of PAC
There are many kinds of production processes of PAC, such as neutralization production of PAC, precipitation production of PAC, thermal decomposition production of PAC, etc. But the main processes are acid-leaching technology and sol-gel method. Now let's talk about these two mainstream processes.
* Acid-Leaching Technology
Acid-leaching technology is the mainstream process for the production of industrial grade PAC, which requires raw materials such as bauxite, calcium aluminate, industrial grade hydrochloric acid or waste acid.
For more details, please refer to: What is the Main Source of PAC Flocculant?
The basic principle of acid dissolution method is to grind the ore fines, and then add acid to dissolve. Dissolution is usually carried out at normal pressure and temperature, at the same time of dissolution, PAC is generated. After that, the alkalinity is adjusted to more than 80% with calcium aluminate powder.
Al2O3 + 3HCl = Al2(OH)3Cl3
Al2(OH)3Cl3 + CaO·Al2O3 → Al2(OH)nCl6-n + CaCl2
It should be noted that the acid-leaching technology is simple and there are wide raw material sources, but a large amount of acid is consumed in the production process, and proper treatment of waste acid is extremely necessary.
* Sol-Gel Method
The sol-gel method is the mainstream production process for the production of drinking water grade and high purity PAC, and its raw materials are aluminum hydroxide, calcium aluminate or sodium aluminate and food grade hydrochloric acid.
2Al(OH)3 + 3HCl = Al2(OH)3Cl3 + 3H2O
Al2(OH)3Cl3 + CaO·Al2O3 → Al2(OH)nCl6-n + CaCl2
The production method can achieve uniform mixing of raw materials at the molecular level, which is conducive to the preparation of PAC with high purity and high performance.
In addition, PAC can also be produced by * direct dissolution method, and its raw materials are aluminum scraps, aluminum ash and aluminum slag from aluminum processing, and hydrochloric acid.
Because of less investment and equipment, simple process and easy operation, direct dissolution method was popular in China in the 1970s. And there are still many small factories using this method. However, the product produced by this method has more impurities, in particular, heavy metal content is easy to exceed the standard, and the product quality is unstable.
The Value of PAC Flocculant
As an excellent polymer flocculant, PAC plays an important role in the field of water treatment. It can not only effectively reduce the turbidity and chroma in the water, remove suspended matter, colloids and some organic matter, but also remove some heavy metal ions through adsorption, precipitation and other mechanisms. In addition, PAC flocculant also has good decolorization and deodorization ability, which is of great significance for improving water quality and protecting ecological environment.
In short, polyaluminum chloride is an awesome water treatment chemical. If you are interested in it, welcome to contact us. Aquaenjoy is committed to providing high quality and cost-effective products!