The process flow of the method for preparing iron phosphate of the present invention includes reacting iron and phosphoric acid to generate ferrous dihydrogen phosphate Fe(H PO ) (that is, iron), and reacting ferrous dihydrogen phosphate and hydrogen peroxide to form a ferric phosphate suspension (that is, Oxidation), heating to obtain iron phosphate solid (i.e. hydrolysis, filtration, washing), through drying and dehydration (i.e. dehydration) to form anhydrous iron phosphate.
Concrete production technological process can be: (1) ferrite process configuration 16-25% phosphoric acid solution: phosphoric acid (preferably food grade) is slowly stirred into pure water, and is mixed with standard phosphoric acid solution.
In the reactor, stack the iron rods of the specification, add an appropriate amount of standard phosphoric acid solution, be heated to 70-95 ℃ and carry out the iron reaction Fe+2H3PO4=Fe(H2PO4)2+H2, after the reaction 3-8 hours, measure dihydrogen phosphate When the content of ferrous Fe(H2PO4)2 reaches about 18-20%, the reaction solution is filtered until it is clean and transparent without suspended sediment, and the obtained filtrate is used for the oxidation process.
(2) oxidizing operation The filtrate is squeezed into the reactor, heated to 18-45 ℃, start stirring, slowly add hydrogen peroxide (can be technical grade) with a trickle, react after 50-70 minutes, continue to stir, Add 30-55% polyethylene glycol solution of dispersant until the reaction is complete. The amount of hydrogen peroxide added is set according to the needs of the reaction, which can usually be slightly larger than the amount of reaction completed by the process. The amount of dispersant added can be based on process conditions. determined experimentally or empirically.
The reaction equation is: 2Fe(H2PO4)2+H2O2=2FePO4+2H3PO4+2H2O.
(3) hydrolysis process Add an appropriate amount of distilled water to the solution after oxidation, stir after about 5-10 minutes, be heated to 70-90 DEG C, be incubated after 50-70 minutes, fully hydrolyze, and fully analyze the iron phosphate crystal.
(4) Pressure filtration washing process The hydrolyzed feed liquid is separated by pressure filtration with a filter press, the filtrate is collected, the filtered solid phase material is introduced into the centrifuge, washed with water, and then dried, and after the collection and washing Washing and drying are repeated until the pH value of the washed solution reaches the above range.
(5) Drying and dehydration process The surface water of the solid ferric phosphate after being spun in the centrifuge is removed by flash evaporation to produce dry ferric phosphate dihydrate FePO4·2H2O. Then, the iron phosphate dihydrate is introduced into the stove, and dehydrated at a high temperature of 380-420 ° C to form iron phosphate.
