Polyaluminium chloride in the water purification process why water insoluble? Insoluble in water, also known as insoluble residue. Its main components are sand, clay, calcium and magnesium carbonate and organic residues, etc. It is a major technical index to evaluate the mineral quality of soluble salts such as salt, potash and trona and to classify ore grade. Polyaluminium chloride in the process of water purification in the water insolubles problems encountered because the traditional polyaluminum chloride and the new PAC, the raw materials used in the general composition of the complex, the more finely crushed, oxidation The higher the aluminum dissolution rate, will result in insoluble precipitate difficult. Solid-liquid separation methods: 1, through the filter to deal with interception of solid-liquid separation; 2, through the solid-liquid two phase difference between the heavy separation; (1), centrifugal separation: centrifugal force, the proportion of different substances were separated. As the centrifuge and other tailings processing equipment can produce a very high angular velocity, the centrifugal force far greater than gravity, so the solution is easy to precipitate sediment: and because of the different gravity of the material subjected to different centrifugal force, thus settling velocity is different, can So that different substances to achieve the separation of osteomyelitis. (2) Gravitational Settlement: It relies on the gravitational field of the Earth. The solid-liquid separation equipment uses the difference in density between particles and fluids to cause relative movement and settlement, ie gravity sedimentation. Gravitational settling is the easiest way to separate dust particles from a gas stream. Only the larger particles, the smaller the gas velocity, the role of gravity sedimentation was more obvious; 3, other materials and chemical properties, such as low temperature into a solid, high temperature into a liquid state. For separation. At present, the following three methods are generally used to achieve solid-liquid separation in China: natural sedimentation method usually takes a very long time and requires a certain site to build a large sedimentation tank; plate and frame filter press filter, but the investment is high, the cost is large, Horizontal spiral centrifuge, the cost of investment in a large industry; dosing polyacrylamide and other coagulant, control the amount put, the effect is good. Polyaluminum chloride through the frame filter can be continuously filtered liquid separation of solid insoluble particles, does not affect the use of the solution. With frame filter press can maintain degreasing liquid and the low concentration of particles in the phosphating solution to extend the life of the solution to extend the cleaning cycle of the spray system. Plate frame filter press is characterized by continuous cleaning solution, the output of non-aqueous waste, degreasing tank and the phosphate tank can not long down slot, reducing the waste of solution. In the raw materials of polyaluminum chloride produced by the filter water purifying material factory, in addition to aluminum and iron, it also contains other metals such as calcium and magnesium. The appearance of these so-called "impurity" metal ions is caused by impure raw materials. Experiments show that, like calcium, magnesium and other metal ions, often can improve the flocculation effect of the main coagulant, for some industrial wastewater, the effect is more significant.