Process for preparing battery-grade high-purity nano iron phosphate

Abstract

The invention discloses a process for preparing battery-grade high-purity nano iron phosphate. The process comprises the steps that the pH is improved by using a titanium dioxide by-product, impurities are removed and a solution is purified by adding iron powder, then ferrous oxidization is performed to obtain ferric iron, the pH of iron sulfate is regulated, ferric ions in the iron sulfate are extracted by adopting di(2-ethylhexyl) phosphoric acid, a washed organic phase is obtained through 5-6 level counter-current extraction, 5-6 level counter-current acid solution washing and 2-3 level counter-current pure water washing, sulfonated kerosene is distilled out, the organic phase obtained after distillation is mixed with a catalyst, reaction is performed at the temperature of 300-320 DEG C for 3-4 hours, and the material obtained after reaction is washed by adding ethyl alcohol and is dried to obtain the high-purity nano iron phosphate. According to the process for preparing the high-purity nano iron phosphate, the high-purity nano iron phosphate can be prepared through the titanium dioxide by-product, the obtained iron phosphate is high in purity, small in particle size and large in specific surface area, the ferro-phosphorus ratio is 0.995-1.01, and the wastewater production amount is small.

Description

technical field [0001] The invention relates to a process for battery-grade high-purity nano-iron phosphate, which belongs to the field of new energy battery materials. Background technique [0002] Iron phosphate , also known as ferric phosphate, iron orthophosphate, molecular formula FePO4, is a white, off-white monoclinic crystal powder. It is the salt of iron salt solution and sodium phosphate, and the iron in it is positive trivalent. Its main purpose is to manufacture Lithium iron phosphate battery pool materials, catalysts and ceramics, etc. [0003] High Purity Ferric Phosphate Dihydrate color It is nearly white or light (light) yellow White Powder, with the loss of crystal water, the color gradually turns yellow, and the pure anhydrous is yellow-white powder. Phosphorus (P) in dihydrate ferric phosphate is off-white or dark off-white when it exceeds the standard; if iron exceeds the standard, it is dark yellow. The ratio of phosphorus to iron is the most...

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Problems solved by technology

[0005] However, the present iron phosphate preparation generally adopts the reaction process of ferrous salt, oxidizing agent and phosphate, but there are problems: 1. Since ferric ions are particularly easy to be hydrolyzed and precipitated, hydrogen oxidation is easily generated during the preparation of ferric phosphate Iron and other impurities lead to low purity of ferric phosphate; 2. The purification of ferrous solution, especially the manganese, magnesium, nickel, sodium and other ions, is difficult to remove at a lower cost, so high-purity iron raw materials must be used. For example, high-purity iron powder and high-purity ferrous phosphate are prepared, resulting in high cost; 3. Liquid phase precipitation to prepare ferric phosphate has problems such as too coarse particle size, while ultra-fine ferric phosphate prepared by sol and other methods has impurities that are not easy to wash off and other shortcomings

[0006] At the same time, ferrous sulfate, a by-product of titanium dioxide, has an annual output of one million tons. Its recycling is generally used as a low-value-added water purifier. Because it contains a large amount of impurity ions such as magnesium, manganese, and zinc, it is not suitable for its high-end Recycling has a big handicap

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