Preparation method of iron phosphate with high tap density

Abstract

The invention discloses a preparation method of iron phosphate with a high tap density. The preparation method comprises the following steps: red phosphorus and iron powder are mixed in an inert atmosphere, then alcohol is added, the obtained mixture is placed in a ball mill and is ball-milled, and the ball-milled mixture is calcined at a high temperature in an inert atmosphere in an atmosphere furnace to obtain a ferrophosphorus alloy; the ferrophosphorus alloy is placed in a rotary furnace, and is oxidatively calcined by an oxygen-rich gas at 500-650 DEG C for 4-5 h to obtain a calcined powder; and the calcined powder undergoes jet milling to obtain a powder with a particle size of 0.5-2 [mu]m, and the powder is screened, and undergoes electromagnetic iron removal to obtain anhydrous iron phosphate. The preparation method has the advantages of simple process and low cost, and the obtained iron phosphate has the advantages of high tap density, good sphericity and large particle size,and is suitable for preparing high-compactness lithium iron phosphate.

Description

technical field [0001] The invention relates to a method for preparing iron phosphate with high tap density, belonging 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 FePO 4 , is a white, off-white monoclinic crystal powder. The material containing crystal water is a white slightly powdery material, and the anhydrous iron phosphate is a white slightly yellow material. 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 con...

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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 to react phosphate with iron salt to obtain ferric phosphate dihydrate, and then undergo 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 in the calcination process is high. According to actual production, each ton of anhydrous iron phosphate consumes 3500-5500 kWh of electricity, and the equipment requirements are high, the process is cumbersome, and the sintering process will cause phosphorus Volatilization loss, resulting in impurity, and easy to cause product pollution, and there is also the problem of low tap density

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