Low-cost preparation method of anhydrous iron phosphate

Abstract

The invention discloses a low-cost preparation method of anhydrous iron phosphate. The method comprises the following steps: adding iron oxide red wastes produced in a steelmaking plant to a sulfuricacid solution, performing pulpifying, heating and reacting the obtained slurry, filtering the reacted slurry, washing the obtained filter residues with hot pure water, drying the washed filter residues, carrying out jet milling, and allowing the milled filter residues to go through an electromagnetic iron remover to obtain an iron oxide red material; adding the iron oxide red material to phosphoric acid, adding anhydrous alcohol, performing stirring, conveying the obtained solution into a spray dryer through a high-pressure pump, and using hot nitrogen as a heat source to obtain a dry material; and adding the dry material to anhydrous alcohol, washing the dry material, stopping washing when the content of free phosphoric acid in the dry material is less than 20 ppm, and drying the washed material to obtain the anhydrous iron phosphate. The method has the advantages of simple process and low cost, and the obtained anhydrous iron phosphate has the advantages of good dispersibility, highpurity, few impurity phases, large specific surface area, and easiness in subsequent grinding.

Description

technical field [0001] The invention relates to a preparation method of low-cost anhydrous iron phosphate, which belongs to the field of lithium battery new energy materials. Background technique [0002] Iron phosphate, also known as ferric phosphate, Iron orthophosphate , the molecular formula is FePO4, is a white, off-white monoclinic crystal powder. is iron saline solution and sodium phosphate The role of the salt, the iron in which is positive trivalent. Its main purpose is to manufacture lithium iron phosphate battery materials, catalysts and ceramics. [0003] At present, in the preparation of lithium iron phosphate, most manufacturers use anhydrous iron phosphate as the precursor. This is because iron phosphate dihydrate contains 20% water, and a large amount of water vapor is generated during the calcination process, resulting in a high dew point in the calcination furnace, which is easy to causing fluctuations in carbon content [0004] At present, the prep...

AI Technical Summary

Problems solved by technology

[0003] At present, in the preparation of lithium iron phosphate, most manufacturers use anhydrous iron phosphate as the precursor. This is because iron phosphate dihydrate contains 20% water, and a large amount of water vapor is generated during the calcination process, resulting in a high dew point in the calcination furnace, which is easy to causing fluctuations in carbon content

[0004] At present, the preparation of anhydrous ferric phosphate is the reaction of phosphate and iron salt to obtain ferric phosphate dihydrate, and then undergoes high-temperature calcination (generally at a temperature of 500-600°C) to remove two crystal waters to obtain anhydrous ferric phosphate. Due to high-temperature calcination, As a result, the specific surface area of ​​anhydrous iron phosphate decreases sharply, and the energy consumption of the calcination process is high. According to actual production, each ton of anhydrous iron phosphate consumes 3500-5500 kWh of electricity, and the requirements for equipment are high, the process is cumbersome, and the sintering process will cause phosphorus Volatilization loss, resulting in impurity, and easy to cause product pollution