Phosphogypsum purifying agent and purifying process

Abstract

The invention belongs to the technical field of ardealite purification. The invention relates to an ardealite purifying agent, in particular to an ardealite purifying agent and an ardealite purifying process. The product provided by the invention comprises spherical hollow graphene oxide particles; the spherical hollow graphene oxide particles are used as a flotation agent to be applied to a purification process in the phosphogypsum purification process; a preparation method of the spherical hollow graphene oxide particles comprises the following steps: taking 80 to 100 parts by weight of graphene oxide, 2 to 4 parts by weight of a nonionic surfactant, 8 to 10 parts by weight of lauryl amine, 0.2 to 0.4 part by weight of dopamine and 400 to 500 parts by weight of an ethanol solution; the preparation method comprises the following steps: mixing lauryl amine and a nonionic surfactant with an ethanol solution, heating, stirring and dissolving, adding graphene oxide, carrying out ultrasonic dispersion, adding dopamine, carrying out stirring reaction in a weakly alkaline environment, carrying out spray granulation, and screening to obtain the spherical hollow graphene oxide particles.

Description

Technical Field

[0001] The present invention belongs to the technical field of phosphogypsum purification. More specifically, it relates to a purification agent and a purification process for phosphogypsum. Background Art

[0002] Phosphogypsum contains dyed organic impurities and metal impurities, etc. These dyed impurities limit the bottleneck of deep processing of phosphogypsum and its application in building materials and chemical fillers, especially in the aspects of being used as fillers for polymers, plaster for painting, and gypsum decorative products. Therefore, in order to improve the resource utilization rate of phosphogypsum and expand the utilization ways, it is necessary to purify phosphogypsum. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: the problem that phosphogypsum must be treated during the process of resource utilization. The inventor found during the research process that due to the inclusion of dyed impurities such as organic impurities and non-ferrous metal ions in phosphogypsum, the light reflectance of the surface of the phosphogypsum product is affected, and the change in light reflectance will affect its whiteness; and the reflectance is related to the material composition and element types in phosphogypsum. For example, organic impurities generally appear black, resulting in phosphogypsum showing grayish-white or grayish-black; and the impurity metal elements Fe, Cr, Cu, Mn, etc. in phosphogypsum exist in the form of sulfates, phosphates, oxides, etc. on the surface of phosphogypsum particles, in the gaps or wrapped in the calcium sulfate dihydrate crystals, making phosphogypsum show the color of the dyed metal ions. The inventor found that especially the Fe element contained therein often has the highest content and has the greatest impact on whiteness, usually making phosphogypsum show different degrees of gray, yellow and other colors. In view of the above technical problems, the present invention provides a purification agent and a purification process for phosphogypsum.

[0004] The object of the present invention is to provide a purification agent for phosphogypsum.

[0005] Another object of the present invention is to provide a purification process for phosphogypsum.

[0006] The above objects of the present invention are achieved by the following technical solutions: A purification agent for phosphogypsum, comprising spherical hollow graphene oxide particles; During the purification process of phosphogypsum, the spherical hollow graphene oxide particles are used as a flotation agent in the purification process; The preparation steps of the spherical hollow graphene oxide particles include: By weight, take 80 - 100 parts of graphene oxide, 2 - 4 parts of non-ionic surfactant, 8 - 10 parts of dodecylamine, 0.2 - 0.4 parts of dopamine, and 400 - 500 parts of ethanol solution; The graphene oxide is transparent graphene oxide with a light transmittance of more than 90%; First, mix dodecylamine and non-ionic surfactant with an ethanol solution, heat and stir to dissolve, then add graphene oxide, disperse it by ultrasonic wave, and then add dopamine. Under a weakly alkaline environment, stir and react, followed by spray granulation and screening to obtain spherical hollow graphene oxide particles.

[0007] The beneficial effects of the above technical solution: In the above technical solution, the self-prepared spherical hollow graphene oxide particles are used as a flotation agent in the purification process of phosphogypsum to achieve the purification of phosphogypsum.

[0008] Specifically, first, during the preparation process of the spherical hollow graphene oxide particles, with the assistance of non-ionic surfactant, dodecylamine is dissolved in the ethanol solution. Subsequently, under the action of ultrasonic wave, the lamellar structure of graphene oxide is gradually peeled off by the cavitation effect of ultrasonic wave. In particular, under the action of non-ionic surfactant, the increase in the interlayer spacing of graphene oxide is further aggravated, which is conducive to its full peeling. After peeling, dodecylamine can be adsorbed and fixed on the surface of graphene oxide with the assistance of non-ionic surfactant and dopamine. During the spray granulation process, due to the oxidative self-polymerization reaction of dopamine occurring under a weakly alkaline environment, the lamellar structure of graphene oxide forms a spherical structure, and the presence of non-ionic surfactant and dodecylamine is conducive to the formation of a hollow structure during the spray granulation process; The reason for expecting to obtain spherical hollow graphene oxide particles with the above structure is that, on the one hand, by using its hollow structure, during the flotation purification process of phosphogypsum, various impurities can be carried to the surface by its lower density, avoiding the mixing of graphene oxide into phosphogypsum and thus affecting the purity of phosphogypsum; on the other hand, under the action of dodecylamine and the presence of the conjugated region of graphene oxide, it can form adsorption with organic impurities in phosphogypsum. In particular, the hydroxyl and carboxyl groups at the edge of the graphene oxide structure and the epoxy groups in the conjugated region can effectively adsorb and fix metal ions in phosphogypsum, such as iron ions; and, due to the structure of the spherical hollow graphene oxide particles after full peeling during the preparation process, the conjugated region of graphene oxide can be effectively exposed, so that the conjugated region can be further used to firmly adsorb metal ions. This is mainly because iron ions, as charge carriers, can form electrostatic attraction or π-π stacking interaction with the π electron cloud of graphene oxide.

[0009] Furthermore, the non-ionic surfactant is selected from any one of fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, polysorbate-20, and fatty acid diethanolamide.

[0010] Furthermore, the mass fraction of the ethanol solution is 60 - 80%.

[0011] Since dodecylamine is a solid at room temperature, if it is directly dissolved in water, its solubility is generally relatively low. However, with the assistance of an ethanol solution with a certain mass fraction, it can be successfully dissolved, which is beneficial to the subsequent formation of an interaction between the dissolved dodecylamine and graphene oxide.

[0012] Further, the ultrasonic dispersion includes: maintaining ultrasonic dispersion for 2 - 4 h at a temperature of 60 - 70 °C and an ultrasonic frequency of 160 - 180 kHz.

[0013] Under the action of the above temperature and ultrasonic frequency, ultrasonic treatment for a sufficient time is conducive to the full exfoliation of the layered structure of graphene oxide to form a single-layer structure.

[0014] Further, the weakly alkaline environment is: pH is 7.8 - 8.2.

[0015] Further, the preparation steps of the spherical hollow graphene oxide particles further include: By weight, take 80 - 100 parts of graphene oxide, 2 - 4 parts of non-ionic surfactant, 8 - 10 parts of dodecylamine, 0.2 - 0.4 parts of dopamine, 20 - 30 parts of gelatin solution, and 400 - 500 parts of ethanol solution; First, mix dodecylamine and non-ionic surfactant with the ethanol solution, heat and stir to dissolve, then add graphene oxide, after ultrasonic dispersion, add dopamine and gelatin solution, under a weakly alkaline environment, stir and react, then spray granulate and screen to obtain spherical hollow graphene oxide particles.

[0016] Further, the mass fraction of the gelatin solution is 3 - 6%; and in the gelatin solution, it includes gelatin and water; the isoelectric point of the gelatin is 7.0.

[0017] Beneficial effects of the above technical solution: The above technical solution further introduces gelatin in the preparation process of the spherical hollow graphene oxide particles. The introduction of gelatin not only facilitates the combination of multiple single-layer graphene oxides to form spherical particles during the spray granulation process, but also, most importantly, when added to the purification process of phosphogypsum, the presence of gelatin can improve the strength of the flotation foam to a certain extent, so that the hollow spherical graphene oxide particles can stably exist in the foam, avoiding the settlement of graphene oxide particles caused by foam rupture and affecting the purity of phosphogypsum; Furthermore, gelatin with an isoelectric point of 7.0 is selected mainly because, during the preparation process of spherical hollow graphene oxide particles, after the addition of the gelatin solution, the reaction system is in a weakly alkaline environment, that is, the pH is above 7.0. At this time, the hydroxide ions in the solution can react with the carboxyl groups in the gelatin molecular structure, resulting in the ionization of the carboxyl groups. Due to the electrostatic repulsion caused by the same negative charge, the gelatin molecular chains are fully stretched, so that the layered structures of multiple single-layer graphene oxides can be adsorbed and fixed, which is conducive to the stable formation of the spherical structure. In addition, during the purification process of phosphogypsum, an acidic reaction system is often used. At this time, the hydrogen ions in the solution system can protonate the amino groups in the gelatin molecular structure. Due to the electrostatic repulsion generated by the same positive charge, the generation of this electrostatic repulsion can not only cause the expansion of the spherical structure, making the single-layer graphene oxide fully exposed, but also enable components such as dodecylamine to be fully released, realizing the further effective adsorption of impurities in the system by the product.

[0018] A purification process for phosphogypsum uses the above-mentioned phosphogypsum purifying agent as a flotation agent; And the purification process for phosphogypsum includes the following purification steps: After crushing and refining the phosphogypsum, add it to a flotation cell, then add water, and then adjust the pH to 2.0 - 2.2; Then add the phosphogypsum purifying agent to the flotation cell, after ultrasonic dispersion, add a foaming agent, stir and react, then skim the foam, collect the remaining slurry in the flotation cell, perform centrifugal separation, and dry it to complete the purification of phosphogypsum.

[0019] Furthermore, the dosage of the phosphogypsum purifying agent is 1.2 - 1.5% of the mass of the phosphogypsum.

[0020] Furthermore, the foaming agent is selected from methyl isobutyl carbinol; and the dosage of the foaming agent is 0.03 - 0.05% of the mass of the phosphogypsum. Description of the Drawings Figure 1 : shows the color state of the refined phosphogypsum before purification in Example 1 of the present application; Figure 2 : shows the color state of the phosphogypsum after purification in Example 1 of the present application; Figure 3 : shows the comparison of the color state of the refined phosphogypsum before purification and the color state of the phosphogypsum after purification in Example 1 of the present application. Detailed Embodiments

[0022] The following specific examples are used to further illustrate the present invention, 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 technical field.

[0023] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0024] Example 1 By weight, successively take 80 parts of graphene oxide, 2 parts of non-ionic surfactant, 8 parts of dodecylamine, 0.2 part of dopamine, 20 parts of a 3% gelatin solution by mass fraction, and 400 parts of a 60% ethanol solution by mass fraction; Among them, the graphene oxide selected is graphene oxide with a D50 of 300 nm; And, the graphene oxide is transparent graphene oxide with a light transmittance of more than 90%; The non-ionic surfactant is selected from: fatty alcohol polyoxyethylene ether; The gelatin solution is obtained by dissolving gelatin and water. Among them, the isoelectric point of the gelatin is 7.0; First, mix dodecylamine and non-ionic surfactant and pour them into the ethanol solution. Under the conditions of a temperature of 45 °C and a stirring speed of 300 r / min, heat and stir to dissolve for 30 min; then add graphene oxide. Under the conditions of a temperature of 60 °C and an ultrasonic frequency of 160 kHz, keep warm and ultrasonically disperse for 2 h, then add dopamine, adjust the pH to 7.8. Under this weakly alkaline environment, under the condition of a stirring speed of 200 r / min, stir and react for 40 min, then convey the material to a spray dryer, control the feeding rate at 100 g / min, and under the conditions of a main disk speed of 8000 r / min, an inlet air temperature of 135 °C, and an outlet air temperature of 105 °C in the spray dryer, spray granulate. Subsequently, screen out particles with a particle size distribution range of 10 - 80 μm to obtain spherical hollow graphene oxide particles; Using the obtained spherical hollow graphene oxide particles as a flotation agent, which is a purification agent for phosphogypsum, for use in the purification process of phosphogypsum; specifically, the purification process includes: Add phosphogypsum to a crusher, crush it and pass through an 80-mesh sieve to obtain refined phosphogypsum; Add the refined phosphogypsum to a flotation cell, and add water 20 times the mass of the refined phosphogypsum to the flotation cell. Stir and mix at a speed of 200 r / min with a stirrer for 30 min, then adjust the pH of the material in the flotation cell to 2.0; then add a purification agent for phosphogypsum at 1.2% of the mass of the refined phosphogypsum to the flotation cell. Under the condition of an ultrasonic frequency of 160 kHz, ultrasonically disperse for 1 h, then add 0.03% of the refined phosphogypsum mass of a foaming agent - methyl isobutyl carbinol. Subsequently, stir and react at a speed of 600 r / min with a stirrer for 2 h, then skim the foam, collect the remaining slurry in the flotation cell, centrifuge and dry to complete the purification of phosphogypsum.

[0025] Example 2 By weight, successively take 90 parts of graphene oxide, 3 parts of non-ionic surfactant, 9 parts of dodecylamine, 0.3 part of dopamine, 24 parts of a 5% gelatin solution, and 460 parts of a 70% ethanol solution; Among them, the graphene oxide selected is graphene oxide with a D50 of 310 nm; And, the graphene oxide is transparent graphene oxide with a light transmittance of more than 90%; The non-ionic surfactant is selected from: nonylphenol polyoxyethylene ether; The gelatin solution is obtained by dissolving gelatin and water, wherein the isoelectric point of the gelatin is 7.0; First, mix dodecylamine and non-ionic surfactant and pour them into the ethanol solution. Under the conditions of a temperature of 48 °C and a stirring speed of 360 r / min, heat and stir to dissolve for 50 min; then add graphene oxide. Under the conditions of a temperature of 65 °C and an ultrasonic frequency of 170 kHz, keep warm and ultrasonically disperse for 3 h, then add dopamine, adjust the pH to 8.0. Under this weakly alkaline environment, under the condition of a stirring speed of 220 r / min, stir and react for 50 min, then transport the material to a spray dryer. Control the feeding rate at 110 g / min. Under the conditions of a main disk speed of 8200 r / min in the spray dryer, an inlet air temperature of 138 °C, and an outlet air temperature of 106 °C, spray granulate, and then screen out particles with a particle size distribution range of 10 - 80 μm to obtain spherical hollow graphene oxide particles; Use the obtained spherical hollow graphene oxide particles as a flotation agent, that is, a purification agent for phosphogypsum, for use in the purification process of phosphogypsum; specifically, the purification process includes: Add phosphogypsum to a crusher, crush it and pass it through a 100-mesh sieve to obtain refined phosphogypsum; Add the refined phosphogypsum to a flotation cell, and add water 22 times the mass of the refined phosphogypsum to the flotation cell. Stir and mix at a speed of 240 r / min with a stirrer for 30 min, then adjust the pH of the material in the flotation cell to 2.1; then add a purification agent for phosphogypsum that is 1.3% of the mass of the refined phosphogypsum to the flotation cell. Under the condition of an ultrasonic frequency of 170 kHz, ultrasonically disperse for 1.5 h, then add 0.04% of the mass of the refined phosphogypsum of the foaming agent - methyl isobutyl carbinol. Subsequently, stir and react at a speed of 700 r / min with a stirrer for 2.5 h, then skim the foam, collect the remaining slurry in the flotation cell, centrifuge and dry to complete the purification of phosphogypsum.

[0026] Example 3 By weight, successively take 100 parts of graphene oxide, 4 parts of non-ionic surfactant, 10 parts of dodecylamine, 0.4 part of dopamine, 30 parts of a 6% gelatin solution, and 500 parts of an 80% ethanol solution; Among them, the graphene oxide selected is graphene oxide with a D50 of 320 nm; And, the graphene oxide is transparent graphene oxide with a light transmittance of more than 90%; The non-ionic surfactant is selected from: octylphenol polyoxyethylene ether; The gelatin solution is obtained by dissolving gelatin and water. Among them, the isoelectric point of the gelatin is 7.0; First, mix dodecylamine and non-ionic surfactant and pour them into an ethanol solution. Under the conditions of a temperature of 50 °C and a stirring speed of 400 r / min, heat and stir to dissolve for 60 min; then add graphene oxide. Under the conditions of a temperature of 70 °C and an ultrasonic frequency of 180 kHz, keep warm and ultrasonically disperse for 4 h, then add dopamine, adjust the pH to 8.2. Under this weakly alkaline environment, under the condition of a stirring speed of 240 r / min, stir and react for 60 min, then transport the material to a spray dryer, control the feeding rate at 120 g / min, and under the conditions of a main disk rotation speed of 8500 r / min and an inlet air temperature of 140 °C and an outlet air temperature of 110 °C in the spray dryer, spray granulate, and then screen out particles with a particle size distribution range of 10 - 80 um to obtain spherical hollow graphene oxide particles; Using the obtained spherical hollow graphene oxide particles as a flotation agent, that is, a purification agent for phosphogypsum, for use in the purification process of phosphogypsum; specifically, the purification process includes: Add phosphogypsum to a crusher, crush it and then pass it through a 120-mesh sieve to obtain refined phosphogypsum; Add the refined phosphogypsum to a flotation cell, and add water 25 times the mass of the refined phosphogypsum to the flotation cell. Use a stirrer to stir and mix at a speed of 300 r / min for 30 min, then adjust the pH of the material in the flotation cell to 2.2; then add a purification agent for phosphogypsum, which is 1.5% of the mass of the refined phosphogypsum, to the flotation cell. Under the condition of an ultrasonic frequency of 180 kHz, ultrasonically disperse for 2 h, then add a foaming agent - methyl isobutyl carbinol, which is 0.05% of the mass of the refined phosphogypsum. Then use a stirrer to stir and react at a speed of 800 r / min for 3 h, then skim the foam, collect the remaining slurry in the flotation cell, centrifuge and dry to complete the purification of phosphogypsum.

[0027] Example 4 Compared with Example 1, the difference in this example is that gelatin is not added, and the other conditions remain unchanged.

[0028] Example 5 Compared with Example 1, the difference in this example is that the isoelectric point of gelatin is 7.8, and the other conditions remain unchanged.

[0029] Comparative Example 1 The difference between this comparative example and Example 1 lies in the preparation method of the purification agent, specifically: By weight, 80 parts of graphene oxide, 2 parts of non-ionic surfactant, 8 parts of dodecylamine, 0.2 part of dopamine, 20 parts of a 3% gelatin solution by mass fraction, and 400 parts of a 60% ethanol solution by mass fraction are taken in sequence; Among them, the graphene oxide selected is graphene oxide with a D50 of 300 nm; Moreover, the graphene oxide is transparent graphene oxide with a light transmittance of more than 90%; The non-ionic surfactant is selected from: fatty alcohol polyoxyethylene ether; The gelatin solution is obtained by dissolving gelatin and water. Among them, the isoelectric point of the gelatin is 7.0; First, dodecylamine and non-ionic surfactant are mixed and poured into the ethanol solution. Under the conditions of a temperature of 45 °C and a stirring speed of 300 r / min, it is heated and stirred for dissolution for 30 min; then graphene oxide and dopamine are added, the pH is adjusted to 7.8, and under this weakly alkaline environment, under the condition of a stirring speed of 200 r / min, after stirring and reacting for 40 min, the material is transported to a spray dryer, the feeding rate is controlled at 100 g / min, and under the conditions of a main disk rotation speed of 8000 r / min, an inlet air temperature of 135 °C, and an outlet air temperature of 105 °C in the spray dryer, spray granulation is carried out, and then particles with a particle size distribution range of 10 - 80 μm are screened out to obtain spherical hollow graphene oxide particles; Since ultrasonic treatment is not used, the lamellar structure of graphene oxide is not effectively exfoliated.

[0030] Comparative Example 2 The difference between this comparative example and Example 1 lies in: Activated carbon of equal mass is used to replace graphene oxide, and the other conditions remain unchanged.

[0031] Comparative Example 3 The difference between this comparative example and Example 1 lies in: Non-ionic surfactant and dopamine are not added, and the other conditions remain unchanged.

[0032] The products obtained from the above examples and comparative examples are subjected to performance tests. The specific test methods and test results are as follows: Product purity test: The purity of CaSO4·2H2O in the product is determined by measuring the content of crystal water. The method used refers to the standard of GB / T 23456-2018 "Phosphogypsum", and 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 into a sample press to be pressed into a test sample plate with a flat surface, no texture, no defects, and no stains. Five test sample plates were pressed for each concentrate under the same conditions, and their whitenesses were measured respectively, and the average value was taken. The specific test results are shown in Table 1; Table 1: Test Results of Product Performance In the same way, the product purity and product whiteness of the phosphogypsum raw material were tested. Its product purity was 67.88% and the whiteness was 29.76%; It can be seen from the test results in Table 1 that the products obtained by the present invention can effectively remove impurities in phosphogypsum, significantly improving its purity and whiteness.

[0033] Moreover, in combination with the attached Figures 1-3 It can be seen that only by treating phosphogypsum with the purification method of the embodiment of the present application, due to the removal of colored impurities such as metal ions such as iron ions in phosphogypsum, it is purified and the color whiteness is improved.

[0034] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A purifying agent for phosphogypsum, characterized in that, including spherical hollow graphene oxide particles; During the purification process of phosphogypsum, the spherical hollow graphene oxide particles are used as a flotation agent in the purification process; The preparation steps of the spherical hollow graphene oxide particles include: By weight, take 80-100 parts of graphene oxide, 2-4 parts of non-ionic surfactant, 8-10 parts of dodecylamine, 0.2-0.4 parts of dopamine, and 400-500 parts of ethanol solution; The graphene oxide is transparent graphene oxide with a light transmittance of more than 90%; First, mix dodecylamine and non-ionic surfactant with the ethanol solution, heat and stir to dissolve, then add graphene oxide, ultrasonically disperse, then add dopamine, and under a weakly alkaline environment, stir and react, followed by spray granulation and screening to obtain spherical hollow graphene oxide particles.

2. The purifying agent for phosphogypsum according to claim 1, characterized in that, The non-ionic surfactant is selected from any one of fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, polysorbate-20, and fatty acid diethanolamide.

3. The purifying agent for phosphogypsum according to claim 1, wherein The mass fraction of the ethanol solution is 60-80%.

4. The purifying agent for phosphogypsum according to claim 1, wherein The ultrasonic dispersion includes: under the conditions of a temperature of 60-70°C and an ultrasonic frequency of 160-180 kHz, keep warm and ultrasonically disperse for 2-4 h.

5. The purifying agent for phosphogypsum according to claim 1, wherein The weakly alkaline environment is: pH is 7.8-8.

2.

6. The purifying agent for phosphogypsum according to claim 1, wherein The preparation steps of the spherical hollow graphene oxide particles further include: By weight, take 80-100 parts of graphene oxide, 2-4 parts of non-ionic surfactant, 8-10 parts of dodecylamine, 0.2-0.4 parts of dopamine, 20-30 parts of gelatin solution, and 400-500 parts of ethanol solution; First, mix dodecylamine and non-ionic surfactant with the ethanol solution, heat and stir to dissolve, then add graphene oxide, ultrasonically disperse, then add dopamine and gelatin solution, and under a weakly alkaline environment, stir and react, followed by spray granulation and screening to obtain spherical hollow graphene oxide particles.

7. The purifying agent for phosphogypsum according to claim 1, characterized in that, The mass fraction of the gelatin solution is 3-6%; and in the gelatin solution, it includes gelatin and water; the isoelectric point of the gelatin is 7.

0.

8. A purification process for phosphogypsum, characterized in that, Using the purification agent for phosphogypsum according to any one of claims 1-7 as a flotation agent; And, the purification process of the phosphogypsum includes the following purification steps: After crushing and refining the phosphogypsum, add it to a flotation cell, then add water, and then adjust the pH to 2.0-2.2; Then add the purification agent for phosphogypsum to the flotation cell, ultrasonically disperse, then add a foaming agent, stir and react, scrape the foam, collect the remaining slurry in the flotation cell, centrifuge and dry to complete the purification of the phosphogypsum.

9. The purification process of phosphogypsum according to claim 8, characterized in that, The dosage of the purification agent for phosphogypsum is 1.2-1.5% of the mass of the phosphogypsum.

10. The purification process of phosphogypsum according to claim 8, characterized in that, The foaming agent is selected from methyl isobutyl carbinol; and the dosage of the foaming agent is 0.03-0.05% of the mass of the phosphogypsum.

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