Zinc phosphate, colorless crystalline or white microcrystalline powder, corrosive and deliquescent. Soluble in inorganic acid, ammonia water, ammonium salt solution; insoluble in ethanol; almost insoluble in water, its solubility in water decreases with the increase of temperature. When heated to 100 C, two crystalline water is lost and anhydrous substance is formed. It is used as the base material of various coatings such as aldehyde, phenolic aldehyde, epoxy resin, chlorinated rubber, flame retardant of synthetic macromolecule materials, and also used to produce water-soluble coatings and non-toxic anti-rust pigments.

synthetic method

1. Complex decomposition method

The trisodium phosphate solution was added into the reactor, and zinc sulfate solution was slowly added under stirring. The compound decomposition reaction was carried out at 70-80 ~C. After the complete reaction, the sulfate ion was removed by filtering and rinsing with water. Then, the product of zinc phosphate dihydrate was prepared by grinding and drying at 120 ~C. The reaction equation: 3ZnSO4+2Na3PO4_Zn3(PO4)2+3Na2SO4

2. Zinc oxide process

The diluted 15% phosphoric acid solution was added into the reactor, and the zinc phosphate slurry with a concentration of about 20% was slowly added to react under stirring to produce zinc phosphate. The temperature was kept below 30 ~C. The zinc phosphate dihydrate seed was added to the reactor. The product was heated to 80 ~C under the condition of PH value 3. The product was filtered, washed by hot water, crushed and dried at 90 ~C. The reaction equation is 2H3PO4+3ZnO_Zn3(PO4)2.2H_2O+H_2O.

3. The precipitation of tetrahydrate is obtained by heating the dilute aqueous solution of zinc sulfate and disodium hydrogen phosphate (molar ratio is 3:2). In addition, tetrahydrate can also be prepared by reaction of dilute phosphoric acid solution with zinc oxide or zinc carbonate. Anhydrous zinc phosphate was obtained by heating at 250 C.