Does anyone know how to produce polyaluminium chloride from aluminium hydroxide? I think it needs to be heated at high pressure with hydrochloric acid. But, I don't know the proper design pressure.
There are two processes to manufacture Polyaluminium Chloride (PAC). The first method is by Gypsum Process, where the raw materials are Al(OH)3, HCl, H2SO4 and CaCO3. This process produces gypsum as a by-product, which is difficult to disposed off. The product is 10% Al2O3 content PAC. Thatswhy, the second process (Pressure Process) is preferred over the first one. In the Pressure Process, the raw materials are Al2O3 and HCl and there is no byproduct. The final product is 18% Al2O3 PAC product, which is a basic composition of PAC. The other formulations are made from 18% PAC. The Gypsum Process is being used by some of the older companies in far east asia whereas the new projects mainly in Europe and Latin America are based on Pressure Process.
The raw materials are charged to glass-lined reactor(s). The system is heated by supplying low and medium pressure steam gradually and subequently cooled down using warm water circuit once the desired concentration of PAC is obtained.