A method for purifying and refining phosphogypsum

Abstract

The present invention belongs to the technical field of purification of phosphogypsum. More specifically, it relates to a method for purifying and refining phosphogypsum. The specific purification steps of the present invention include: ball-milling phosphogypsum to adjust the sphericity of the phosphogypsum to 0.55 - 0.65 to obtain ball-milled material; adjusting the moisture content of the ball-milled material to 20 - 25% to obtain wet ball-milled material; after completely freezing the wet ball-milled material, freeze-pressing it for 10 - 30 min under the condition of a pressure of 2.0 - 5.0 MPa to obtain pressed material; adding the pressed material into a flotation cell, adding water to the pressed material, and then adjusting the pH to 2.5 - 2.7; subsequently adding a capturing agent, carrying out ultrasonic stirring reaction, then adding a foaming agent, continuing ultrasonic stirring reaction, skimming the foam, collecting the remaining slurry in the flotation cell, dehydrating, and drying, thus completing the purification and refining of phosphogypsum. The natural pH of the phosphogypsum is 2.4 - 2.6; and the whiteness of the phosphogypsum is 30 - 35%.

Description

Technical Field

[0001] The present invention belongs to the technical field of phosphogypsum purification, and more specifically, relates to a phosphogypsum purification method. Background Art

[0002] Phosphogypsum is an industrial solid waste produced in the process of preparing phosphoric acid by wet process, and its output is extremely large. Phosphogypsum contains a large amount of impurities, mainly including organic matter, silicon, etc. These impurities will reduce the purity of phosphogypsum, and impurities will delay the setting time of gypsum products and reduce the hardening strength.

[0003] In addition, silicon impurities (mainly quartz) are detrimental to the thermal decomposition process of phosphogypsum and will affect the quality of cement clinker. Organic matter comes from the entrainment of the phosphate ore itself and the organic additives in the phosphoric acid production process. These impurities mainly affect the whiteness and structural strength of phosphogypsum products, seriously restricting its large-scale application. Based on this, it is necessary to develop a practical purification method for phosphogypsum to remove organic matter, quartz, soluble fluorine and phosphorus impurities, and minimize the adverse factors caused by its subsequent use. Summary of the invention

[0004] The technical problem to be solved by the present invention is that it is difficult to effectively remove various types of impurities contained in the traditional phosphogypsum purification process, thereby affecting its whiteness or structural strength and other properties. The present invention provides a phosphogypsum purification method.

[0005] The purpose of the present invention is to provide a method for purifying phosphogypsum.

[0006] The above-mentioned purpose of the present invention is achieved through the following technical solutions: A method for purifying phosphogypsum, the specific purification steps comprising: Ball milling the phosphogypsum to adjust the sphericity of the phosphogypsum to 0.55-0.65 to obtain a ball mill material; Adjust the moisture content of the ball mill to 20-25% to obtain wet ball mill. After the wet ball mill material is completely frozen, it is frozen and pressed for 10-30 minutes at a pressure of 2.0-5.0 MPa to obtain a pressed material; Add the squeezed material into the flotation tank, add water to the squeezed material, and adjust the pH to 2.5-2.7; Then, a capture agent is added, and after ultrasonic stirring reaction, a frother is added, and after ultrasonic stirring reaction, the foam is scraped, and the remaining slurry in the flotation tank is collected, dehydrated, and dried, thereby completing the purification of phosphogypsum.

[0007] The beneficial effects of the above technical solution are: First, the phosphogypsum is pretreated by ball milling. During the ball milling process, the first thing that happens is the particle breakage. As the ball milling time increases, the particle size gradually decreases. At the same time, the morphology of the particles may also change. This is mainly because during the long ball milling process, the friction and collision between the particles increase, and the irregular edges and corners will be flattened, so that the particles gradually tend to be spherical. Therefore, the phosphogypsum particles can be controlled within the expected sphericity range by ball milling. Under the condition of particles with corresponding sphericity, they are frozen and squeezed after spraying water. Among them, the water can gradually diffuse and penetrate into the interior along the pores on the surface of the phosphogypsum, and during freezing, the water can penetrate into the interior of the phosphogypsum. During the process, the volume of water increases, so that the pores are widened. In addition, during the freezing process, hydrophilic substances or water-soluble substances are easily introduced into the ice crystals along with the freezing process. During the pressing process, the ice crystals are very brittle and are easily broken under the action of mechanical pressure. The breaking process will drive the pores to break, so that the phosphogypsum is further refined and the ice crystals inside are released. At this time, along with the release of the ice crystals, the hydrophilic substances and water-soluble substances are easily released, thereby avoiding the retention of impurities in the internal pores, accelerating the dissolution process of impurities in the subsequent flotation process, and improving the final purity of the product. The reason why the sphericity needs to be controlled within a reasonable range is that the inventors have found that a certain sphericity can make the particles stacked relatively more tightly, so that they can be effectively stressed during the pressing process; and, during the pressing process, particles with higher sphericity are more uniform in hand; however, since the improvement of its sphericity depends on long-term ball milling, too long a time of ball milling can easily lead to particles that are too fine in size, resulting in excessive surface energy of the particles and agglomeration, thereby affecting the dispersion of the particles in the subsequent flotation process and affecting the purification effect.

[0008] Furthermore, the specific purification step also includes: The squeezed material is added to the flotation tank, and water is added to the squeezed material. The viscosity of the material in the flotation tank is adjusted to 1500-2000 mPa·s by adjusting the amount of water added, and the pH is adjusted to 2.5-2.7 by using sulfuric acid solution or sodium hydroxide solution.

[0009] Beneficial effects of the above technical solution: By rationally regulating the viscosity of the material in the flotation tank within a suitable range before flotation and maintaining a certain viscosity range, during the flotation process, it is beneficial for the impurity components to be suspended under the action of ultrasonic stirring, thereby assisting the capture agent to capture the impurity components well, and, under the action of the frother, it is also easy to form stable foam, thereby avoiding the sedimentation of granular impurities after flotation; if the viscosity is too high and the material is too viscous, it will lead to difficulties in mixing or dispersing the components, thereby affecting the flotation efficiency.

[0010] Furthermore, the capture agent is prepared by compounding a quaternary ammonium salt capture agent and a non-ionic capture agent in a mass ratio of 5-7:1; Furthermore, the amount of the capture agent is 0.03-0.05% of the mass of the phosphogypsum; Wherein, the quaternary ammonium salt capture agent is selected from any one of: dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, dodecyl dimethyl benzyl ammonium chloride, and hexadecyl dimethyl benzyl ammonium chloride; Wherein, the nonionic capture agent is selected from any one of octylphenol polyoxyethylene ether-10, fatty alcohol polyoxyethylene ether-9, polyoxyethylene sorbitan monolaurate, PEG-400 monostearate, polyoxyethylene coconut amine, and polyoxyethylene octylphenyl ether.

[0011] Beneficial effects of the above technical solution: The inventors have found that a single capture agent is easily affected by the pH of the system, thereby affecting the capture efficiency. By compounding a certain amount of non-ionic capture agents, this effect can be alleviated, thereby ensuring a better capture effect.

[0012] Further, the foaming agent is selected from any one of methyl isobutyl carbinol, cyclohexanone, methyl ethyl ketone, ethyl acetate, butyl acetate, PEG-200, and PEG-400; Furthermore, the dosage of the foaming agent is 0.01-0.02% of the mass of the phosphogypsum.

[0013] Furthermore, the ultrasonic stirring reaction is: ultrasonic stirring reaction for 40-80 min under the conditions of ultrasonic frequency of 70-90 kHz and stirring speed of 200-300 r / min.

[0014] Furthermore, the natural pH of the phosphogypsum is 2.4-2.6; and the whiteness of the phosphogypsum is 30-35%.

[0015] Furthermore, the specific purification step also includes: Pour the phosphogypsum into a ball mill jar, and add zirconium oxide ball milling beads at a ball-to-material mass ratio of 30-35:1, wherein the number ratio of ball milling beads with a diameter of 8 cm, ball milling beads with a diameter of 5 cm, and ball milling beads with a diameter of 3 cm is 1:2:5; then continue ball milling and mixing at a rotation speed of 300-320 r / min and a revolution speed of 200-220 r / min until the sphericity of the phosphogypsum is adjusted to 0.55-0.65 to obtain ball mill material.

[0016] Furthermore, the specific purification step also includes: After the abrasive is spread flat, water is sprayed on the abrasive to adjust the moisture content of the abrasive to 20-25% to obtain wet abrasive. Wherein, the moisture content is tested and calibrated according to the following method: After the ball mill material is sprayed with water, it is sampled and transferred to an oven at a temperature of 100°C, and dried continuously until constant weight is obtained. The moisture content is calibrated according to the difference in mass before and after drying. DETAILED DESCRIPTION

[0017] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0018] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0019] Example 1 Pour the phosphogypsum into a ball mill jar, and add zirconium oxide ball milling beads according to a ball-to-material mass ratio of 30:1, wherein the number ratio of the ball milling beads with a diameter of 8 cm, the ball milling beads with a diameter of 5 cm, and the ball milling beads with a diameter of 3 cm is 1:2:5; then, continue ball milling and mixing at a rotation speed of 300 r / min and a revolution speed of 200 r / min until the sphericity of the phosphogypsum is adjusted to 0.55, thereby obtaining a ball mill material; The natural pH of the phosphogypsum is 2.4; and the whiteness of the phosphogypsum is 30%; After the ball abrasive is spread flat, water is sprayed on the ball abrasive to adjust the water content of the ball abrasive to 20% to obtain wet ball abrasive; Wherein, the moisture content is tested and calibrated according to the following method: After the ball mill is sprayed with water, a sample is taken and transferred to an oven at 100°C for continuous drying until constant weight is reached. The moisture content is calibrated according to the difference in mass before and after drying. The wet ball mill material is completely frozen at -20°C, and then kept warm and frozen for 10 minutes at a pressure of 2.0 MPa to obtain the pressed material; Add the squeezed material into the flotation tank, add water to the squeezed material, adjust the viscosity of the material in the flotation tank to 1500mPa·s by adjusting the amount of water added, and then adjust the pH to 2.5 by using sulfuric acid solution or sodium hydroxide solution; Then, a capture agent is added, and the mixture is stirred and reacted for 40 minutes under the conditions of an ultrasonic frequency of 70 kHz and a stirring speed of 200 r / min. Then, a frother is added, and the mixture is stirred and reacted for 40 minutes under the conditions of an ultrasonic frequency of 70 kHz and a stirring speed of 200 r / min. The foam is scraped, and the remaining slurry in the flotation tank is collected, dehydrated, and dried, thereby completing the purification of phosphogypsum. The capture agent is prepared by compounding a quaternary ammonium salt capture agent and a non-ionic capture agent in a mass ratio of 5:1; Furthermore, the amount of the capture agent is 0.03% of the mass of the phosphogypsum; Wherein, the quaternary ammonium salt type capture agent is selected from: dodecyl trimethyl ammonium chloride; Wherein, the non-ionic capture agent is selected from: octylphenol polyoxyethylene ether-10; The foaming agent is selected from methyl isobutyl carbinol; Furthermore, the dosage of the foaming agent is 0.01% of the mass of the phosphogypsum.

[0020] Example 2 Pour the phosphogypsum into a ball mill jar, and add zirconium oxide ball milling beads according to a ball-to-material mass ratio of 32:1, wherein the number ratio of the ball milling beads with a diameter of 8 cm, the ball milling beads with a diameter of 5 cm, and the ball milling beads with a diameter of 3 cm is 1:2:5; then, the ball milling is continued at a rotation speed of 310 r / min and a revolution speed of 210 r / min until the sphericity of the phosphogypsum is adjusted to 0.6, thereby obtaining a ball mill material; The natural pH of the phosphogypsum is 2.5; and the whiteness of the phosphogypsum is 32%; After the ball abrasive is spread flat, water is sprayed on the ball abrasive to adjust the water content of the ball abrasive to 23% to obtain wet ball abrasive; Wherein, the moisture content is tested and calibrated according to the following method: After the ball mill is sprayed with water, a sample is taken and transferred to an oven at 100°C for continuous drying until constant weight is reached. The moisture content is calibrated according to the difference in mass before and after drying. The wet ball mill material is completely frozen at -30°C, and then kept warm and frozen for 20 minutes at a pressure of 3.0 MPa to obtain the squeezed material; The squeezed material is added to the flotation tank, and water is added to the squeezed material. The viscosity of the material in the flotation tank is adjusted to 1800 mPa·s by adjusting the amount of water added, and the pH is adjusted to 2.6 by using sulfuric acid solution or sodium hydroxide solution; Then, a capture agent is added, and the mixture is stirred and reacted for 60 minutes under the conditions of an ultrasonic frequency of 80 kHz and a stirring speed of 260 r / min. Then, a frother is added, and the mixture is stirred and reacted for 60 minutes under the conditions of an ultrasonic frequency of 80 kHz and a stirring speed of 260 r / min. The foam is scraped, and the remaining slurry in the flotation tank is collected, dehydrated, and dried, thereby completing the purification of the phosphogypsum. The capture agent is prepared by compounding a quaternary ammonium salt capture agent and a non-ionic capture agent in a mass ratio of 6:1; Furthermore, the amount of the capture agent is 0.04% of the mass of the phosphogypsum; Wherein, the quaternary ammonium salt type capture agent is selected from: hexadecyltrimethylammonium chloride; Wherein, the nonionic capture agent is selected from: fatty alcohol polyoxyethylene ether-9; The foaming agent is selected from cyclohexanone; Furthermore, the dosage of the foaming agent is 0.015% of the mass of the phosphogypsum.

[0021] Example 3 Pour the phosphogypsum into a ball mill jar, and add zirconium oxide ball milling beads according to a ball-to-material mass ratio of 35:1, wherein the number ratio of the ball milling beads with a diameter of 8 cm, the ball milling beads with a diameter of 5 cm, and the ball milling beads with a diameter of 3 cm is 1:2:5; then, the ball milling is continued at a rotation speed of 320 r / min and a revolution speed of 220 r / min until the sphericity of the phosphogypsum is adjusted to 0.65, thereby obtaining a ball mill material; The natural pH of the phosphogypsum is 2.6; and the whiteness of the phosphogypsum is 35%; After the ball abrasive is spread flat, water is sprayed on the ball abrasive to adjust the water content of the ball abrasive to 25% to obtain wet ball abrasive; Wherein, the moisture content is tested and calibrated according to the following method: After the ball mill is sprayed with water, a sample is taken and transferred to an oven at 100°C for continuous drying until constant weight is reached. The moisture content is calibrated according to the difference in mass before and after drying. The wet ball mill material is completely frozen at -40°C, and then kept warm and frozen for 30 minutes at a pressure of 5.0 MPa to obtain the pressed material; Add the squeezed material into the flotation tank, add water to the squeezed material, adjust the viscosity of the material in the flotation tank to 2000mPa·s by adjusting the amount of water added, and then adjust the pH to 2.7 by using sulfuric acid solution or sodium hydroxide solution; Then, a capture agent is added, and the mixture is stirred and reacted for 80 minutes under the conditions of an ultrasonic frequency of 90 kHz and a stirring speed of 300 r / min. Then, a frother is added, and the mixture is stirred and reacted for 80 minutes under the conditions of an ultrasonic frequency of 90 kHz and a stirring speed of 300 r / min. The foam is scraped, and the remaining slurry in the flotation tank is collected, dehydrated, and dried, thereby completing the purification of phosphogypsum. The capture agent is prepared by compounding a quaternary ammonium salt capture agent and a non-ionic capture agent in a mass ratio of 7:1; Furthermore, the amount of the capture agent is 0.05% of the mass of the phosphogypsum; Wherein, the quaternary ammonium salt type capture agent is selected from: octadecyl trimethyl ammonium chloride; Wherein, the non-ionic capture agent is selected from: polyoxyethylene sorbitan monolaurate; The foaming agent is selected from ethyl acetate; Furthermore, the dosage of the foaming agent is 0.02% of the mass of the phosphogypsum.

[0022] Example 4 The present embodiment is different from the embodiment 1 in that: the squeezed material is added into the flotation tank, and water is added into the squeezed material, and the viscosity of the material in the squeezed material is adjusted to 1200 mPa·s by adjusting the amount of water added, and the other conditions remain unchanged.

[0023] Example 5 The present embodiment is different from the embodiment 1 in that the squeezed material is added into the flotation tank, and water is added into the squeezed material, and the viscosity of the material in the squeezed material is adjusted to 2200 mPa·s by adjusting the amount of water added, and the other conditions remain unchanged.

[0024] Example 6 The difference between this embodiment and embodiment 1 is that no non-ionic capture agent is added, and other conditions remain unchanged.

[0025] Comparative Example 1 Compared with Example 1, this comparative example differs in that: freeze pressing is not used, and other conditions remain unchanged, specifically: Pour the phosphogypsum into a ball mill jar, and add zirconium oxide ball milling beads according to a ball-to-material mass ratio of 30:1, wherein the number ratio of the ball milling beads with a diameter of 8 cm, the ball milling beads with a diameter of 5 cm, and the ball milling beads with a diameter of 3 cm is 1:2:5; then, continue ball milling and mixing at a rotation speed of 300 r / min and a revolution speed of 200 r / min until the sphericity of the phosphogypsum is adjusted to 0.55, thereby obtaining a ball mill material; The natural pH of the phosphogypsum is 2.4; and the whiteness of the phosphogypsum is 30%; After the ball abrasive is spread flat, water is sprayed on the ball abrasive to adjust the water content of the ball abrasive to 20% to obtain wet ball abrasive; Wherein, the moisture content is tested and calibrated according to the following method: After the ball mill is sprayed with water, a sample is taken and transferred to an oven at 100°C for continuous drying until constant weight is reached. The moisture content is calibrated according to the difference in mass before and after drying. Add the ball mill wet material into the flotation tank, add water to the ball mill wet material, adjust the viscosity of the material in the flotation tank to 1500mPa·s by adjusting the amount of water added, and then adjust the pH to 2.5 by using sulfuric acid solution or sodium hydroxide solution; Subsequently, a capture agent is added, and the reaction is carried out under ultrasonic stirring for 40 minutes at an ultrasonic frequency of 70kHz and a stirring speed of 200r / min. Then, a frother is added, and the reaction is carried out under ultrasonic stirring for 40 minutes at an ultrasonic frequency of 70kHz and a stirring speed of 200r / min. The foam is scraped, and the remaining slurry in the flotation tank is collected, dehydrated, and dried to complete the purification of phosphogypsum.

[0026] Comparative Example 2 Compared with Example 1, the difference between this comparative example and Example 1 is that the phosphogypsum is used directly without ball milling, and the other conditions remain unchanged, specifically: After the phosphogypsum is spread flat, water is sprayed on the phosphogypsum to adjust the moisture content of the phosphogypsum to 20%, thereby obtaining wet phosphogypsum; Wherein, the moisture content is tested and calibrated according to the following method: After spraying water, take a sample of the phosphogypsum and transfer it to an oven at 100°C for continuous drying until constant weight is reached. The moisture content is calibrated according to the difference in mass before and after drying. The natural pH of the phosphogypsum is 2.4; and the whiteness of the phosphogypsum is 30%; The wet phosphogypsum material is completely frozen at -20°C, and then kept warm and frozen and pressed at a pressure of 2.0 MPa for 10 minutes to obtain the pressed material; Add the squeezed material into the flotation tank, add water to the squeezed material, adjust the viscosity of the material in the flotation tank to 1500mPa·s by adjusting the amount of water added, and then adjust the pH to 2.5 by using sulfuric acid solution or sodium hydroxide solution; Subsequently, a capture agent is added, and the reaction is carried out under ultrasonic stirring for 40 minutes at an ultrasonic frequency of 70kHz and a stirring speed of 200r / min. Then, a frother is added, and the reaction is carried out under ultrasonic stirring for 40 minutes at an ultrasonic frequency of 70kHz and a stirring speed of 200r / min. The foam is scraped, and the remaining slurry in the flotation tank is collected, dehydrated, and dried to complete the purification of phosphogypsum.

[0027] The performance tests were performed on the products obtained in the above examples and comparative examples. The specific test methods and test results are as follows: Product purity testing: CaSO in the product 4 ·2H 2 The purity of O is determined by measuring the content of crystal water. The method used is based on the GB / T 23456-2018 "Phosphogypsum" standard. The specific test results are shown in Table 1. The whiteness was measured using a YQ-Z-48A whiteness meter. A certain amount of powdered sample was placed in a sample press and pressed into a sample plate with a smooth surface, no texture, no defects, and no stains. Three sample plates were pressed under the same conditions for each concentrate, and the whiteness was measured separately and the average value was taken. The specific test results are shown in Table 1; Table 1: Product performance test results It can be seen from the test results in Table 1 that the product obtained by the present invention has relatively higher purity and excellent whiteness.

[0028] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for purifying phosphogypsum, characterized in that: The specific purification steps include: Ball milling the phosphogypsum to adjust the sphericity of the phosphogypsum to 0.55-0.65 to obtain a ball mill material; Adjust the moisture content of the ball mill to 20-25% to obtain wet ball mill. After the wet ball mill material is completely frozen, it is frozen and pressed for 10-30 minutes at a pressure of 2.0-5.0 MPa to obtain a pressed material; Add the squeezed material into the flotation tank, add water to the squeezed material, and adjust the pH to 2.5-2.7; Then, a capture agent is added, and after ultrasonic stirring reaction, a frother is added, and after ultrasonic stirring reaction, the foam is scraped, and the remaining slurry in the flotation tank is collected, dehydrated, and dried, thereby completing the purification of phosphogypsum.

2. A method for purifying phosphogypsum according to claim 1, characterized in that: The specific purification step also includes: The squeezed material is added to the flotation tank, and water is added to the squeezed material. The viscosity of the material in the flotation tank is adjusted to 1500-2000 mPa·s by adjusting the amount of water added, and the pH is adjusted to 2.5-2.7 by using sulfuric acid solution or sodium hydroxide solution.

3. A method for purifying phosphogypsum according to claim 1, characterized in that: The capture agent is prepared by compounding a quaternary ammonium salt capture agent and a non-ionic capture agent in a mass ratio of 5-7:1; Furthermore, the amount of the capture agent is 0.03-0.05% of the mass of the phosphogypsum; Wherein, the quaternary ammonium salt capture agent is selected from any one of: dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, dodecyl dimethyl benzyl ammonium chloride, and hexadecyl dimethyl benzyl ammonium chloride; Wherein, the nonionic capture agent is selected from any one of octylphenol polyoxyethylene ether-10, fatty alcohol polyoxyethylene ether-9, polyoxyethylene sorbitan monolaurate, PEG-400 monostearate, polyoxyethylene coconut amine, and polyoxyethylene octylphenyl ether.

4. A method for purifying phosphogypsum according to claim 1, characterized in that: The foaming agent is selected from any one of methyl isobutyl carbinol, cyclohexanone, methyl ethyl ketone, ethyl acetate, butyl acetate, PEG-200, and PEG-400; Furthermore, the dosage of the foaming agent is 0.01-0.02% of the mass of the phosphogypsum.

5. A method for purifying phosphogypsum according to claim 1, characterized in that: The ultrasonic stirring reaction is: the ultrasonic stirring reaction is carried out for 40-80 minutes under the conditions of an ultrasonic frequency of 70-90 kHz and a stirring speed of 200-300 r / min.

6. A method for purifying phosphogypsum according to claim 1, characterized in that: The natural pH of the phosphogypsum is 2.4-2.6; and the whiteness of the phosphogypsum is 30-35%.

7. A method for purifying phosphogypsum according to claim 1, characterized in that: The specific purification step also includes: Pour the phosphogypsum into a ball mill jar, and add zirconium oxide ball milling beads at a ball-to-material mass ratio of 30-35:1, wherein the number ratio of ball milling beads with a diameter of 8 cm, ball milling beads with a diameter of 5 cm, and ball milling beads with a diameter of 3 cm is 1:2:5; then continue ball milling and mixing at a rotation speed of 300-320 r / min and a revolution speed of 200-220 r / min until the sphericity of the phosphogypsum is adjusted to 0.55-0.65 to obtain ball mill material.

8. A method for purifying phosphogypsum according to claim 1, characterized in that: The specific purification step also includes: After the ball abrasive is spread flat, water is sprayed on the ball abrasive to adjust the water content of the ball abrasive to 20-25% to obtain wet ball abrasive; Wherein, the moisture content is tested and calibrated according to the following method: After the ball mill material is sprayed with water, it is sampled and transferred to an oven at a temperature of 100°C, and dried continuously until constant weight is obtained. The moisture content is calibrated according to the difference in mass before and after drying.