Method for preparing battery-grade iron phosphate from phosphated residues

Abstract

The invention discloses a method for preparing battery-grade iron phosphate by utilizing phosphated residues. The method comprises the following steps: pre-treating the phosphated residues; alkaline leaching is conducted on the phosphated residues, wherein the phosphated residues are placed in a sodium hydroxide solution with the mass fraction being 30%; decoloring is performed; acid treatment: adding hydrochloric acid into the filtrate to adjust the pH value, adding a solution composed of urotropin, thiourea, tetraethylammonium oxalate, hydrogen peroxide and polydodecyl acrylamide acrylic acid, and stirring; extracting: adding an extracting agent and an organic solution, and extracting under a stirring condition; precipitating: heating the raffinate, adding hexadecyl trimethyl ammonium chloride, and stirring; then adding a ferric nitrate solution to carry out precipitation reaction; the method for preparing the battery material ferric phosphate product by taking phosphated residue solid wastes generated in the steel metal product process as raw materials through the steps of pretreatment, alkaline leaching, decoloration, acid treatment, extraction, precipitation reaction and the like has the advantages of simple process, high product quality, low production cost, high recovery efficiency of phosphorus resources in the waste residues and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing battery-grade iron phosphate by utilizing phosphating slag, and belongs to the technical field of phosphating slag treatment. Background Art

[0002] During the production of steel and metal products, the phosphating treatment of the steel surface will produce solid waste phosphating slag. In addition to a certain amount of water, the main components of phosphating slag are iron phosphate and zinc phosphate. Analysis shows that the mass content of each component in the phosphating slag is approximately: water accounts for 15-20%, TFe (Fe 3+ and Fe 2+ ) accounts for 15-25%, Zn 2+ 2-5%, PO4 3- In addition, the phosphating slag also contains a small amount of Ca 2+ Mg 2+ , Mn 2+ 、Ni 2+ , Cu 2+ The total mass content of impurity elements such as iron and steel is about 0.5-2.0%. At present, the amount of phosphating slag produced in my country accounts for about 0.5-1.0% of the phosphating treatment of steel products, and the amount of phosphating slag solid waste produced each year is as high as more than 500,000 tons. In recent years, with the continuous expansion of the deep processing capacity of steel products in my country's steel enterprises, the treatment / disposal of phosphating slag produced in the metal product process has seriously affected the normal production of enterprises and the quality of phosphating products. At the same time, since phosphating slag solid waste has been included in the "National Hazardous Waste List", if it is discharged at will without treatment, it will also cause environmental pollution problems and waste recyclable valuable chemical resources. And with the rapid development of new energy, lithium iron phosphate used in batteries has become an important raw material. As a precursor of lithium iron phosphate, iron phosphate is an indispensable part of the recycling system of lithium iron phosphate positive electrode materials. How to prepare a method for preparing battery-grade iron phosphate using phosphating slag for the use of phosphating slag has become a problem to be solved. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing battery-grade iron phosphate by using phosphating slag, so as to obtain an iron phosphate product for battery that meets the requirements of HG / T 4701-2014 standard.

[0004] To solve the above technical problems, the purpose of the present invention is achieved as follows:

[0005] The present invention relates to a method for preparing battery-grade iron phosphate using phosphating slag, comprising the following steps:

[0006] S1. Pretreatment of phosphating slag: crush the phosphating slag into particles with a particle size of 100-500 microns, then place the particles in a phosphoric acid aqueous solution, heat in a water bath and stir; remove the upper foam after precipitation, and pass through a 250-mesh sieve in water, retain the sieve, filter, dry and set aside;

[0007] S2, phosphating slag alkaline leaching: the phosphating slag after pretreatment is placed in a 30% by mass sodium hydroxide solution for a certain period of time, and then water is added to adjust the pH value to 10-11, and the reaction is continued for a certain period of time, and then passed through a 500 mesh sieve, and the filtrate is collected;

[0008] S3, decolorization: add activated carbon to the filtrate obtained in the previous step, stir for adsorption, filter, and collect the filtrate;

[0009] S4, acid treatment: adding hydrochloric acid to the filtrate obtained in the previous step to adjust the pH value to 6-6.5, then adding a solution consisting of hexamethylenetetramine, thiourea, tetraethylammonium oxalate, hydrogen peroxide, and polydodecyl acrylamide acrylic acid and stirring for a certain period of time;

[0010] S5, extraction: adding an extractant and an organic solution to the liquid prepared in the previous step, extracting under stirring conditions, adding a phosphoric acid aqueous solution to the obtained raffinate to adjust its pH value to 4-4.5 for preparing iron phosphate;

[0011] S6, precipitation: under stirring conditions, the raffinate of step S5 is heated to 80-90°C, and hexadecyltrimethylammonium chloride is added, and stirred for a certain period of time; then, ferric nitrate solution is added to cause precipitation reaction, and when the pH value of the suspension reaches 1.5-2.5, the suspension is filtered, and the obtained solid is washed with water and dried to obtain the ferric phosphate product.

[0012] On the basis of the above scheme and as a preferred scheme of the above scheme: in step S1, the phosphoric acid aqueous solution includes 20-30% by mass of analytically pure phosphoric acid, and the mass ratio of phosphating slag particles to phosphoric acid aqueous solution is 1:2-5.

[0013] On the basis of the above scheme and as a preferred scheme of the above scheme: in step S2, the mass ratio of the phosphating slag to the sodium hydroxide solution is 1:5-10.

[0014] On the basis of the above scheme and as a preferred scheme of the above scheme: in step S3, the amount of activated carbon used is 2-3% of the mass of the filtrate, the adsorption time is 30-45 minutes, and the adsorption temperature is room temperature.

[0015] On the basis of the above scheme and as a preferred scheme of the above scheme: in step S4, the amount of urotropine used is 0.1-0.2% of the mass of the filtrate, the amount of thiourea used is 0.05-0.1% of the mass of the filtrate, the amount of tetraethylammonium oxalate used is 0.1-0.2% of the mass of the filtrate, the amount of hydrogen peroxide used is 0.2-0.3% of the mass of the filtrate; the amount of the polydodecyl acrylamide acrylic acid group used is 0.05-0.08% of the mass of the filtrate.

[0016] On the basis of the above scheme and as a preferred scheme of the above scheme: in step S5, the extractant is an organic amine extractant; the organic solvent is one or more of benzene, toluene or kerosene.

[0017] On the basis of the above scheme and as a preferred scheme of the above scheme: in the step S6, the amount of the hexadecyltrimethylammonium chloride used is 0.3-0.5% of the weight of the raffinate.

[0018] The beneficial effects of the present invention are as follows: the method for preparing battery-grade iron phosphate using phosphating slag involved in the present invention uses the phosphating slag solid waste generated in the process of steel and metal products as raw material, and is prepared through pretreatment, alkali leaching, decolorization, acid treatment, extraction and precipitation reaction and other steps. The method has the advantages of simple process, high product quality, low production cost, and high efficiency of phosphorus resource recovery in waste slag. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with specific embodiments.

[0020] Example

[0021] A method for preparing battery-grade iron phosphate using phosphating slag involved in this embodiment comprises the following steps:

[0022] S1. Pretreatment of phosphating slag: crush the phosphating slag into particles with a particle size of 100-500 microns, then place the particles in a phosphoric acid aqueous solution, heat in a water bath and stir; remove the upper foam after precipitation, and pass through a 250-mesh sieve in water, retain the sieve, filter, dry and set aside. Specifically in this embodiment, the average particle size is crushed to about 300 microns.

[0023] Further, in step S1, the phosphoric acid aqueous solution includes 20-30% by mass of analytically pure phosphoric acid, and the mass ratio of the phosphating slag particles to the phosphoric acid aqueous solution is 1:2-5. Specifically, in this embodiment, the phosphoric acid aqueous solution includes 25% by mass of analytically pure phosphoric acid, and the mass ratio of the phosphating slag particles to the phosphoric acid aqueous solution is 1:4.

[0024] S2. Alkaline leaching of phosphating slag: the phosphating slag after pretreatment is placed in a 30% by mass sodium hydroxide solution for reaction for 30 minutes, then water is added to adjust the pH value to 10, the reaction is continued for 20 minutes, and the slag is passed through a 500 mesh sieve to collect the filtrate.

[0025] Furthermore, in step S2, the mass ratio of the phosphating slag to the sodium hydroxide solution is 1:5-10, and specifically 1:8 in this embodiment.

[0026] S3, decolorization: add activated carbon to the filtrate obtained in the previous step, stir for adsorption, filter and collect the filtrate.

[0027] Further, in step S3, the amount of activated carbon is 2-3% of the mass of the filtrate, the adsorption time is 30-45 minutes, and the adsorption temperature is room temperature. In this embodiment, the amount of activated carbon is 3% of the mass of the filtrate, and the adsorption time is 30 minutes.

[0028] S4, acid treatment: hydrochloric acid is added to the filtrate obtained in the previous step to adjust the pH value to 6-6.5, and then a solution consisting of hexamethylenetetramine, thiourea, tetraethylammonium oxalate, hydrogen peroxide, and polydodecyl acrylamide acrylic acid is added and stirred for 10 minutes.

[0029] Further, in step S4, the amount of urotropine used is 0.1-0.2% of the mass of the filtrate, the amount of thiourea is 0.0.5-0.1% of the mass of the filtrate, the amount of tetraethylammonium oxalate is 0.1-0.2% of the mass of the filtrate, and the amount of hydrogen peroxide is 0.2-0.3% of the mass of the filtrate; the amount of the polydodecyl acrylamide acrylic acid group is 0.05-0.08% of the mass of the filtrate. In this embodiment, the amount of urotropine used is 0.1% of the mass of the filtrate, the amount of thiourea is 0.1% of the mass of the filtrate, the amount of tetraethylammonium oxalate is 0.1% of the mass of the filtrate, and the amount of hydrogen peroxide is 0.3% of the mass of the filtrate; the amount of the polydodecyl acrylamide acrylic acid group is 0.08% of the mass of the filtrate.

[0030] S5, extraction: adding an extractant and an organic solution to the liquid prepared in the previous step, extracting under stirring, adding a phosphoric acid aqueous solution to the obtained raffinate to adjust its pH value to 4-4.5 for preparing iron phosphate.

[0031] Furthermore, in step S5, the extractant is an organic amine extractant; the organic solvent is one or more of benzene, toluene or kerosene. In this embodiment, the organic solvent is kerosene.

[0032] S6, precipitation: under stirring conditions, the raffinate of step S5 is heated to 80-90° C., and hexadecyltrimethylammonium chloride is added, and stirred for 15 minutes; then, ferric nitrate solution is added to cause precipitation reaction, and when the pH value of the suspension reaches 2, the suspension is filtered, and the obtained solid is washed with water and dried to obtain the ferric phosphate product.

[0033] Furthermore, in step S6, the amount of hexadecyltrimethylammonium chloride used is 0.3-0.5% by weight of the raffinate. Specifically in this embodiment, the amount of hexadecyltrimethylammonium chloride used is 0.4% by weight of the raffinate.

[0034] After analysis, determination and calculation, the product quality meets the standard requirements of "Iron Phosphate for Batteries (HG / T 4701-2014)", and the total recovery rate of phosphate in phosphating slag is 87.9%.

[0035] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for preparing battery-grade iron phosphate using phosphating slag, characterized in that: The steps include: S1. Pretreatment of phosphating slag: crush the phosphating slag into particles with a particle size of 100-500 microns, then place the particles in a phosphoric acid aqueous solution, heat in a water bath and stir; remove the upper foam after precipitation, and pass through a 250-mesh sieve in water, retain the sieve, filter, dry and set aside; S2, phosphating slag alkaline leaching: the phosphating slag after pretreatment is placed in a 30% by mass sodium hydroxide solution for a certain period of time, and then water is added to adjust the pH value to 10-11, and the reaction is continued for a certain period of time, and then passed through a 500 mesh sieve, and the filtrate is collected; S3, decolorization: add activated carbon to the filtrate obtained in the previous step, stir for adsorption, filter, and collect the filtrate; S4, acid treatment: adding hydrochloric acid to the filtrate obtained in the previous step to adjust the pH value to 6-6.5, then adding a solution consisting of hexamethylenetetramine, thiourea, tetraethylammonium oxalate, hydrogen peroxide, and polydodecyl acrylamide acrylic acid and stirring for a certain period of time; S5, extraction: adding an extractant and an organic solution to the liquid prepared in the previous step, extracting under stirring conditions, adding a phosphoric acid aqueous solution to the obtained raffinate to adjust its pH value to 4-4.5 for preparing iron phosphate; S6, precipitation: under stirring conditions, the raffinate of step S5 is heated to 80-90°C, and hexadecyltrimethylammonium chloride is added, and stirred for a certain period of time; then, ferric nitrate solution is added to cause precipitation reaction, and when the pH value of the suspension reaches 1.5-2.5, the suspension is filtered, and the obtained solid is washed with water and dried to obtain the ferric phosphate product.

2. The method for preparing battery-grade iron phosphate using phosphating slag according to claim 1, characterized in that: In step S1, the phosphoric acid aqueous solution includes 20-30% by mass of analytically pure phosphoric acid, and the mass ratio of the phosphating slag particles to the phosphoric acid aqueous solution is 1:2-5.

3. The method for preparing battery-grade iron phosphate using phosphating slag according to claim 1, characterized in that: In step S2, the mass ratio of the phosphating slag to the sodium hydroxide solution is 1:5-10.

4. The method for preparing battery-grade iron phosphate using phosphating slag according to claim 1, characterized in that: In step S3, the amount of activated carbon used is 2-3% of the mass of the filtrate, the adsorption time is 30-45 minutes, and the adsorption temperature is room temperature.

5. The method for preparing battery-grade iron phosphate using phosphating slag according to claim 1, characterized in that: In step S4, the amount of urotropine used is 0.1-0.2% of the mass of the filtrate, the amount of thiourea used is 0.05-0.1% of the mass of the filtrate, the amount of tetraethylammonium oxalate used is 0.1-0.2% of the mass of the filtrate, the amount of hydrogen peroxide used is 0.2-0.3% of the mass of the filtrate; the amount of polydodecyl acrylamide acrylic acid group used is 0.05-0.08% of the mass of the filtrate.

6. The method for preparing battery-grade iron phosphate using phosphating slag according to claim 1, characterized in that: In step S5, the extractant is an organic amine extractant; the organic solvent is one or more of benzene, toluene or kerosene.

7. The method for preparing battery-grade iron phosphate using phosphating slag according to claim 1, characterized in that: In step S6, the amount of hexadecyltrimethylammonium chloride used is 0.3-0.5% of the weight of the raffinate.