CN115403019A - A kind of preparation method of iron phosphate - Google Patents

Abstract

The invention relates to the technical field of chemical production, in particular to a preparation method of iron phosphate. The method comprises the following steps: mixing and dissolving ammonium dihydrogen phosphate powder and water, carrying out solid-liquid separation, and purifying a liquid phase to obtain an ammonium dihydrogen phosphate solution; mixing and dissolving the copperas and water, carrying out solid-liquid separation, purifying a liquid phase to obtain a ferrous sulfate solution, then adjusting the pH value to 1.6-1.8 by using sulfuric acid, mixing the ferrous sulfate solution, the ammonium dihydrogen phosphate solution and hydrogen peroxide, and reacting to obtain a mother solution of a crude iron phosphate product; washing the ferric phosphate crude product mother liquor, mixing with water and phosphoric acid, and aging to obtain an aged mother liquor; and carrying out solid-liquid separation on the aged mother liquor to obtain the iron phosphate. The invention prepares the high-purity (more than 99 percent) battery-grade iron phosphate product under the conditions of no byproduct generation, no need of further regulating the pH value of a system and product purification, and reduces the cost by 10 to 20 percent compared with the method for preparing the iron phosphate by taking phosphoric acid or industrial monoammonium phosphate as a phosphorus source.

Description

A kind of preparation method of iron phosphate

technical field

The invention relates to the technical field of chemical production, in particular to a preparation method of iron phosphate.

Background technique

With the continuous development of new energy vehicles towards green and low-carbon, commercial power batteries mainly use lithium iron phosphate as the mainstream. As the precursor of lithium iron phosphate, iron phosphate has high requirements on its purity. In the currently disclosed prior art, ferric phosphate is mostly prepared by reacting ferrous sulfate, iron and iron slag mixture, etc. with phosphoric acid and phosphate. Since the synthesis process will be doped with metal and non-metallic impurities, ammonium salt, Ammonia, strong alkali, etc. are used to remove impurities, so more by-products and solid waste will be produced; and the increase of ammonium salts in such process systems will increase the content of ammonia nitrogen in industrial wastewater, resulting in higher environmental protection costs and greater environmental threats big. In addition, the traditional method of preparing ferric phosphate also uses strong acid to react with pure iron, and the ferric iron product produced continues to react with phosphoric acid to produce ferric phosphate products. Due to the introduction of strong acid, this process requires the addition of a large amount of ammonia, ammonium, sodium hydroxide or Potassium hydroxide is used to adjust the pH value, thereby increasing the concentration of impurity ions in the product and the difficulty of wastewater treatment. The introduction of a large number of impurity ions will seriously interfere with the cycle performance and power of the battery during charging and discharging, and affect the stability of the battery.

Therefore, it is a technical problem to be solved by those skilled in the art to provide a low-cost preparation method of environmentally friendly iron phosphate.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of iron phosphate, to solve the defective that existing technology exists.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a kind of preparation method of ferric phosphate, comprises the following steps:

(1) Dissolving after mixing the ammonium dihydrogen phosphate powder with water, separating the solid and liquid, and purifying the liquid phase to obtain the ammonium dihydrogen phosphate solution;

(2) Mix green vitriol with water and dissolve, separate the solid from the liquid, and purify the liquid phase to obtain a ferrous sulfate solution, then use sulfuric acid to adjust the pH value to 1.6-1.8, mix it with ammonium dihydrogen phosphate solution and hydrogen peroxide, and react Obtain ferric phosphate crude product mother liquor after;

(3) mix with water and phosphoric acid after washing iron phosphate crude product mother liquor, carry out aging, obtain aging mother liquor;

(4) After the solid-liquid separation of the aged mother liquor, ferric phosphate is obtained.

Preferably, the temperature for dissolving the ammonium dihydrogen phosphate powder in the step (1) is 50-70° C., and the time for dissolving treatment is 20-40 minutes; the particle size of the ammonium dihydrogen phosphate powder is 100-200 μm, and the obtained phosphoric acid The mass fraction of ammonium dihydrogen solution is 23-24%.

Preferably, the mass fraction of iron in the step (2) ferrous sulfate solution is 5-6%; the mass ratio of iron, hydrogen peroxide, and ammonium dihydrogen phosphate in the ferrous sulfate solution is 1:1.4-1.5 : 1~1.5.

Preferably, the ferrous sulfate solution in the step (2) is mixed with ammonium dihydrogen phosphate solution and hydrogen peroxide in a manner that simultaneously drips ammonium dihydrogen phosphate solution and hydrogen peroxide in the ferrous sulfate solution, and the ammonium dihydrogen phosphate and hydrogen peroxide are added dropwise. The feeding time of hydrogen peroxide is 50-70 minutes.

Preferably, the reaction temperature of the step (2) is 60-70° C., and the reaction time is 70-90 minutes.

Preferably, the mass fraction of phosphoric acid in the step (3) is 80-85%, and the mass ratio of the washed crude iron phosphate, water and phosphoric acid is 8-12:90-110:1.

Preferably, the aging temperature in the step (3) is 80-95° C., and the aging time is 150-200 min.

Preferably, the step (4) further includes washing and drying after the solid-liquid separation; wherein the water temperature in steps (3) and (4) is greater than or equal to 90° C. during washing.

Preferably, the drying temperature in the step (4) is 80-120° C., and the drying time is 6-12 hours.

Preferably, the step (1) purification includes dissolving, filtering, and cation exchange resin adsorption.

It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

The present invention uses ferrous sulfate as the iron source, reducing the generation of by-product salt; using fertilizer grade ammonium dihydrogen phosphate solution as the phosphorus source, the purified ammonium dihydrogen phosphate and hydrogen peroxide are added dropwise at the same time, and the ferrous sulfate is oxidized at the same time It reacts with ammonium dihydrogen phosphate to generate ferric phosphate, which improves the multi-step synthesis of ferrous iron in the traditional process and the introduction of various impurity ions in the process of strong acidification of iron, and reduces the cost of raw materials in the process of strong acidification of iron; the washing process uses hot water, which can Effectively removes residual impurities.

The present invention produces high-purity (over 99%) battery-grade iron phosphate products without the generation of by-products, without the need for further adjustment of system pH and product purification, and relatively uses phosphoric acid or industrial monoammonium phosphate as the phosphorus source to prepare phosphoric acid The iron method reduces the cost by 10-20%.

Description of drawings

Fig. 1 is the flow chart that the present invention prepares iron phosphate.

Detailed ways

The invention provides a kind of preparation method of ferric phosphate, comprises the following steps:

(1) Dissolving after mixing the ammonium dihydrogen phosphate powder with water, separating the solid and liquid, and purifying the liquid phase to obtain the ammonium dihydrogen phosphate solution;

(2) Mix vitriol with water and dissolve, separate the solid from the liquid, and purify the liquid phase to obtain a ferrous sulfate solution, then use sulfuric acid to adjust the pH value to 1.6-1.8, preferably 1.65-1.75, and mix with ammonium dihydrogen phosphate Solution and hydrogen peroxide are mixed, and after the reaction, the ferric phosphate crude product mother liquor is obtained;

(3) mix with water and phosphoric acid after washing iron phosphate crude product mother liquor, carry out aging, obtain aging mother liquor;

(4) After the solid-liquid separation of the aged mother liquor, ferric phosphate is obtained.

In the present invention, the temperature for dissolving ammonium dihydrogen phosphate powder in the step (1) is 50-70°C, preferably 55-65°C, and the time for dissolving treatment is 20-40min, preferably 25-35min; The particle size of the ammonium hydrogen phosphate powder is 100-200 μm, preferably 120-180 μm, and the mass fraction of the obtained ammonium dihydrogen phosphate solution is 23-24%, preferably 23.2-23.6%.

In the present invention, the mass fraction of iron in the step (2) ferrous sulfate solution is 5-6%; the mass ratio of iron, hydrogen peroxide, and ammonium dihydrogen phosphate in the ferrous sulfate solution is 1:1.4 ~1.5:1~1.15, preferably 1:1.42~1.48:1.05~1.13.

In the present invention, the ferrous sulfate solution in the step (2) is mixed with ammonium dihydrogen phosphate solution and hydrogen peroxide in a manner that simultaneously drips ammonium dihydrogen phosphate solution and hydrogen peroxide in the ferrous sulfate solution, and the dihydrogen phosphate The feeding time of ammonium and hydrogen peroxide is 50-70 minutes, preferably 55-64 minutes.

In the present invention, the reaction temperature of the step (2) is 60-70° C., preferably 62-66° C., and the reaction time is 70-90 minutes, preferably 75-85 minutes.

In the present invention, the mass fraction of the hydrogen peroxide is 20-40%, preferably 25-35%.

In the present invention, the concentration of sulfuric acid in the step (2) is 90-98%, preferably 95-98%.

In the present invention, the mass fraction of phosphoric acid in the step (3) is 80-85%, preferably 81-84%, and the mass ratio of the washed crude iron phosphate, water and phosphoric acid is 8-12:90-110: 1. Preferably 9-11:95-105:1.

In the present invention, the aging temperature in step (3) is 80-95°C, preferably 85-90°C, and the aging time is 150-200min, preferably 160-190min.

In the present invention, the step (4) further includes washing and drying after the solid-liquid separation; wherein the water temperature in steps (3) and (4) is greater than or equal to 90°C, preferably greater than or equal to 92°C.

In the present invention, the drying temperature in the step (4) is 80-120° C., preferably 90-110° C., and the drying time is 6-12 hours, preferably 8-10 hours.

In the present invention, the purification in the step (1) is cation exchange resin adsorption.

In the present invention, the step (2) is purified by cation exchange resin adsorption.

The technical solutions provided by the present invention will be described in detail below in conjunction with the examples, but they should not be interpreted as limiting the protection scope of the present invention.

Example 1

A preparation method for iron phosphate, comprising the following steps:

(1) Mix the ammonium dihydrogen phosphate powder with a particle size of 100 μm and water and add it to the reactor, heat the temperature of the reactor to 60°C, keep it warm for 30 minutes, separate the mixed liquid from solid to liquid, and pass the liquid phase through cation exchange resin After the adsorption, the ammonium dihydrogen phosphate solution was obtained with a phosphate radical mass fraction of 23%;

(2) dissolving after vitriol is mixed with water, solid-liquid separation, the mass concentration concentration that liquid phase obtains through cation-exchange resin adsorption is the ferrous sulfate solution of 5%, and it is as bottom liquid, adopts 98% sulfuric acid to dilute the obtained system The pH value was adjusted to 1.8, and the ammonium dihydrogen phosphate solution and hydrogen peroxide (30%) were added dropwise to the bottom solution simultaneously, and the feeding time was controlled to be 60 minutes, and then the oxidation and synthesis reaction were carried out for 15 minutes to obtain the crude ferric phosphate mother liquor, in which sulfurous acid The mass ratio of iron, hydrogen peroxide, and ammonium dihydrogen phosphate in the iron solution is 1:1.45:1-1.09;

(3) With hot water at 100°C as the washing liquid, the ferric phosphate crude product mother liquor is washed by filter press with a filter press until the obtained filtrate is in a colorless and transparent state, and the solid material obtained after the press filter washing is mixed with water and the mass fraction is 80-85% phosphoric acid is mixed according to the mass ratio of 10:100:1, and aged at 90°C for 180 minutes to obtain the aged mother liquor;

(4) Press filter the aged mother liquor with a filter press, use 100°C hot water as the washing liquid, carry out filter press washing of the obtained solid material with a filter press, and transfer the obtained solid material to 100°C after the press filter washing In an oven, dry for 8 hours to obtain iron phosphate, the yield of the obtained product is 87% (yield=actual product yield/theoretical product yield), and the purity is 99.95%.

Example 2

A preparation method for iron phosphate, comprising the following steps:

(2) Mix the ammonium dihydrogen phosphate powder with a particle size of 150 μm and water and add it to the reactor, heat the temperature of the reactor to 50°C, keep it warm for 40 minutes, separate the mixed liquid from solid to liquid, and pass the liquid phase through cation exchange resin After the adsorption, the ammonium dihydrogen phosphate solution with a phosphate mass fraction of 23-24% is obtained;

(2) dissolving after vitriol is mixed with water, solid-liquid separation, the mass concentration concentration that the liquid phase obtains through cation exchange resin adsorption is the ferrous sulfate solution of 6%, and it is used as bottom liquid, adopts 90% sulfuric acid to dilute the obtained system The pH value was adjusted to 1.7, and the ammonium dihydrogen phosphate solution and hydrogen peroxide (20%) were added dropwise to the bottom liquid at the same time, and the feeding time was controlled to be 50 minutes, and then the oxidation and synthesis reactions were carried out for 15 minutes to obtain the mother liquor of ferric phosphate crude product, wherein sulfurous acid The mass ratio of iron in the iron solution, hydrogen peroxide, and phosphate in the ammonium dihydrogen phosphate solution is 1:1.4:1;

(3) With hot water at 90°C as the washing liquid, the ferric phosphate crude product mother liquor is washed by filter press with a filter press until the obtained filtrate is in a colorless and transparent state, and the solid material obtained after the press filter washing and water and the mass fraction are 80% phosphoric acid was mixed according to the mass ratio of 8:90:1, and aged at 80°C for 200 minutes to obtain the aged mother liquor;

(4) Filter the aged mother liquor with a filter press, use hot water at 90°C as the washing liquid, carry out filter press washing of the obtained solid material with a filter press, and transfer the obtained solid material to 80°C after the filter press washing In an oven, dry for 12 hours to obtain iron phosphate, the yield of the obtained product is 85% (yield=actual product yield/theoretical product yield), and the purity is 99.95%.

Example 3

A preparation method for iron phosphate, comprising the following steps:

(3) Mix the ammonium dihydrogen phosphate powder with a particle size of 200 μm and water and add it to the reactor, heat the temperature of the reactor to 70°C, keep it warm for 20 minutes, separate the mixed liquid from solid to liquid, and pass the liquid phase through cation exchange resin Obtaining ammonium dihydrogen phosphate solution phosphate radical mass fraction after adsorption is the solution of 24%;

(2) dissolving after vitriol is mixed with water, solid-liquid separation, the mass concentration concentration that the liquid phase obtains through cation exchange resin adsorption is the ferrous sulfate solution of 6%, and it is used as bottom liquid, adopts 95% sulfuric acid to dilute the obtained system The pH value was adjusted to 1.6, and the ammonium dihydrogen phosphate solution and hydrogen peroxide (40%) were added dropwise to the bottom solution simultaneously, and the feeding time was controlled to be 70 minutes, and then the oxidation and synthesis reaction were carried out for 15 minutes to obtain the crude ferric phosphate mother liquor, in which sulfurous acid The mass ratio of iron, hydrogen peroxide, and ammonium dihydrogen phosphate in the iron solution is 1:1.5:1.15;

(3) With hot water at 98° C. as the washing liquid, the ferric phosphate crude product mother liquor is filtered and washed with a filter press until the obtained filtrate is in a colorless and transparent state. 85% phosphoric acid was mixed according to the mass ratio of 12:110:1, and aged at 95°C for 150 minutes to obtain the aged mother liquor;

(4) Press filter the aged mother liquor with a filter press, use hot water at 98°C as the washing liquid, carry out press filter washing of the obtained solid material with a filter press, and transfer the obtained solid material to 120°C after the press filter washing In an oven, dry for 6 hours to obtain iron phosphate, the product yield is 86% (yield=actual product yield/theoretical product yield), and the purity is 99.95%.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. a preparation method of ferric phosphate, is characterized in that, comprises the following steps: (1) Dissolving after mixing the ammonium dihydrogen phosphate powder with water, separating the solid and liquid, and purifying the liquid phase to obtain the ammonium dihydrogen phosphate solution; (2) Mix green vitriol with water and dissolve, separate the solid from the liquid, and purify the liquid phase to obtain a ferrous sulfate solution, then use sulfuric acid to adjust the pH value to 1.6-1.8, mix it with ammonium dihydrogen phosphate solution and hydrogen peroxide, and react Obtain ferric phosphate crude product mother liquor after; (3) mix with water and phosphoric acid after washing iron phosphate crude product mother liquor, carry out aging, obtain aging mother liquor; (4) After the solid-liquid separation of the aged mother liquor, ferric phosphate is obtained. 2. The preparation method of a kind of iron phosphate according to claim 1, it is characterized in that, the temperature of described step (1) dissolving ammonium dihydrogen phosphate powder is 50～70 ℃, and the time of dissolving treatment is 20～40min The particle size of the ammonium dihydrogen phosphate powder is 100-200 μm, and the mass fraction of the obtained ammonium dihydrogen phosphate solution is 23-24%. 3. according to claim 1 and 2 described a kind of preparation method of ferric phosphate, it is characterized in that, the massfraction of iron in described step (2) ferrous sulfate solution is 5～6%; In ferrous sulfate solution, iron, hydrogen peroxide , The mass ratio of ammonium dihydrogen phosphate in the ammonium dihydrogen phosphate solution is 1:1.4～1.5:1～1.15. 4. the preparation method of a kind of ferric phosphate according to claim 3 is characterized in that, in the described step (2), the mode that ferrous sulfate solution mixes with ammonium dihydrogen phosphate solution, hydrogen peroxide is to ferrous sulfate solution At the same time, the ammonium dihydrogen phosphate solution and hydrogen peroxide are added dropwise, and the feeding time of the ammonium dihydrogen phosphate and hydrogen peroxide is 50-70 minutes. 5. The preparation method of a kind of iron phosphate according to claim 1, 2 or 4, characterized in that, the reaction temperature of the step (2) is 60-70° C., and the reaction time is 70-90 min. 6. the preparation method of a kind of ferric phosphate according to claim 1 is characterized in that, the massfraction of described step (3) phosphoric acid is 80～85%, the mass ratio of ferric phosphate crude product, water and phosphoric acid after washing 8-12:90-110:1. 7. The method for preparing ferric phosphate according to claim 1 or 6, characterized in that the aging temperature in the step (3) is 80-95° C., and the aging time is 150-200 min. 8. the preparation method of a kind of ferric phosphate according to claim 1 is characterized in that, described step (4) also comprises washing and drying after solid-liquid separation; Wherein step (3) and step (4) water temperature during washing Greater than or equal to 90°C. 9 . The method for preparing ferric phosphate according to claim 8 , characterized in that, the drying temperature in the step (4) is 80-120° C., and the drying time is 6-12 hours. 10. The preparation method of a kind of ferric phosphate according to claim 1, is characterized in that, described step (1) purification comprises dissolving, filtering, cation exchange resin adsorption.

Images