Phosphoric acid itself has no binding properties. When it reacts chemically with neutral oxides and weakly alkaline oxides of raw materials such as earth ore clinker to produce phosphate, it shows good adhesion. In addition to chemical reactions with the binding material, it is mainly caused by the polymerization and adhesion of acid phosphates. Phosphate group ions are connected in various ways to macromolecules with a long chain planar network or space skeleton structure. The oxygen in the phosphate group PO4 plays this linking role to solidify and harden the green body.
The formation of acid phosphate depends on the degree of neutralization, that is, the degree of substitution of hydrogen is different. It mainly includes aluminum dihydrogen phosphate and aluminum hydrogen phosphate, which are generally considered to be the main components. Since it is soluble in water at normal temperature, when it is used to form a mixture, it can still maintain plasticity for a long time, but when heated to a certain extent, acid aluminum phosphate can become aluminum pyrophosphate and partial aluminum phosphate, and then occur Polymerization. Therefore, phosphate bricks have the characteristics of high strength and good wear resistance.
After the phosphate bricks are formed, the bricks contain 4% to 5% moisture, so the bricks must be dried to improve their mechanical strength, facilitate transportation and kiln installation, and ensure the appearance quality of the product. Bricks must be naturally dried before entering the drying kiln. The drying time is not less than 12 hours, the kiln temperature is 60~80℃, the kiln temperature is 110~130℃, the drying time is not less than 48h, and the residual moisture after drying is ≤1%.
Compared with high alumina bricks, the service life of small cement rotary kiln phosphate bricks is increased by 1 to 2 times: the load softening temperature is low, the surface is rough, and it is easy to bond with the material. Rongsheng refractory secondary kiln skins are evenly hung, and the bricks and kiln skins are The combination is smooth and firm; if the kiln skin is defective, it is easier to repair it, especially under abnormal kiln operating conditions. The phosphate bricks will not crack or peel, the kiln skin will not collapse or crack, and they have strong adaptability to materials.
