Ardealite harmless treatment process and method thereof

Abstract

The invention discloses a phosphogypsum innocent treatment process and a method thereof, and relates to the technical field of industrial solid waste treatment. When the harmless phosphogypsum is prepared, phosphogypsum is crushed and screened to prepare pretreated phosphogypsum; the preparation method comprises the following steps: carrying out a reaction on nano Fe3O4 and gamma-methacryloxy propyl trimethoxy silane to prepare modified magnetic particles; acrylamide is subjected to initiating polymerization by an initiator, and then the modified magnetic particles are added to prepare a flocculating agent; adjusting the pH value of a flocculating agent and the pretreated ardealite by calcium hydroxide slurry, then adding solid waste fly ash, and standing and maintaining to obtain the harmless ardealite. According to the phosphogypsum harmless treatment process and method, soluble phosphorus in phosphogypsum can be effectively fixed, and pollution is reduced.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste treatment technology, specifically to a harmless treatment process and method for phosphogypsum. Background Technology

[0002] Phosphogypsum is a solid waste generated during the production of phosphoric acid. Its main component is calcium sulfate dihydrate, and it also contains pollutants such as soluble phosphorus, soluble fluorine, and heavy metal ions. These pollutants are easily leached into the environment by rainwater during storage, causing soil and water pollution. Traditional methods for treating phosphogypsum mainly include washing, neutralization, and solidification, but these methods suffer from low treatment efficiency, high costs, and a significant risk of secondary pollution.

[0003] In recent years, polyacrylamide has been widely used as a highly efficient flocculant in wastewater treatment and solid waste disposal. However, ordinary polyacrylamide has limited effectiveness in removing soluble phosphorus, soluble fluoride, and heavy metal ions from phosphogypsum, and it is difficult to achieve long-term stability of the solidified form. Therefore, developing a highly efficient, low-cost, and environmentally friendly technology for the harmless treatment of phosphogypsum is of great significance. The phosphogypsum harmless treatment process and method of this invention can effectively fix waste in phosphogypsum and has broad market prospects. Summary of the Invention

[0004] The purpose of this invention is to provide a harmless treatment process and method for phosphogypsum, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A process and method for the harmless treatment of phosphogypsum, wherein the process involves crushing and screening phosphogypsum to obtain pretreated phosphogypsum; reacting nano-Fe3O4 with γ-methacryloyloxypropyltrimethoxysilane to obtain modified magnetic particles; adding acrylamide to the modified magnetic particles after polymerization initiated by an initiator to obtain a flocculant; adjusting the pH of the flocculant and pretreated phosphogypsum with calcium hydroxide slurry and then adding solid waste fly ash, followed by static curing to obtain harmless phosphogypsum. A process and method for the harmless treatment of phosphogypsum, wherein the preparation steps of the harmless phosphogypsum are as follows: (1) Mix nano Fe3O4, ethanol solution and γ-methacryloxypropyltrimethoxysilane, adjust the pH to 5~5.5 with glacial acetic acid, let stand for 1 h, sonicate for 10~20 min, stir at 550~650 r / min for 1.5~2.5 h at 45~55℃, filter, wash the filter residue with deionized water and anhydrous ethanol 3~5 times respectively, and vacuum dry at 60℃ for 4~6 h to obtain modified magnetic particles; (2) Acrylamide, acryloyloxyethyltrimethylammonium chloride ammonium sulfate, stabilizer and deionized water are mixed in a mass ratio of 1:0.2:0.1:10, nitrogen gas is introduced, and the mixture is reacted at 25~35℃ for 40~60 min. Modified magnetic particle suspension is added, and the mixture is reacted for another 10~20 min. Ammonium persulfate / sodium bisulfite initiator is added, and the mixture is reacted for another 22~26 h. The mixture is filtered, and the filter residue is washed 3~5 times with 50% ethanol solution and acetone respectively. The residue is then vacuum dried at 60℃ for 4~6 h to obtain flocculant. (3) Mix the flocculant solution and pretreated phosphogypsum at a mass ratio of 1: (30~40), stir for 20~30 min, add calcium hydroxide slurry, adjust the pH to 10~12, continue stirring for 40~60 min, add solid waste fly ash at a mass ratio of 0.1~0.2 times that of pretreated phosphogypsum, stir evenly, let stand for 1~3 days, and cure at 20~40℃ and 60%~80% humidity for one week to obtain the product.

[0006] As an optimization, the preparation method of the ethanol solution in step (1) is as follows: anhydrous ethanol and deionized water are mixed at a volume ratio of 4:1.

[0007] As an optimization, the preparation method of the modified magnetic particle suspension in step (2) is as follows: the modified magnetic particles and deionized water are mixed at a mass ratio of 1:6 and ultrasonically dispersed to obtain the suspension.

[0008] As an optimization, the preparation method of the stabilizer in step (2) is as follows: 72% acrylamide, EDTA and deionized water are mixed at a mass ratio of 1:0.02:10, nitrogen gas is introduced, and the mixture is reacted at 65°C for 30 min. Ammonium persulfate / sodium bisulfite initiator is added and the reaction is continued for 5.5~6.5 h. The mixture is washed 3~5 times with anhydrous ethanol and dried under vacuum at 60°C.

[0009] As an optimization, the preparation method of the flocculant solution in step (3) is as follows: flocculant and deionized water are mixed at a mass ratio of 1: (200~300) to obtain the solution.

[0010] As an optimization, the preparation method of the pretreated phosphogypsum in step (3) is as follows: crush the phosphogypsum and sieve it to a particle size of less than 2 mm to obtain the phosphogypsum.

[0011] As an optimization, the calcium hydroxide slurry in step (3) is prepared by mixing calcium oxide and deionized water at a mass ratio of 1: (10~20).

[0012] Compared with the prior art, the beneficial effects achieved by the present invention are: In preparing harmless phosphogypsum, the present invention involves crushing and screening phosphogypsum to obtain pretreated phosphogypsum; reacting nano-Fe3O4 with γ-methacryloxypropyltrimethoxysilane to obtain modified magnetic particles; adding acrylamide to the modified magnetic particles after polymerization initiated by an initiator to obtain a flocculant; and adjusting the pH of the flocculant and pretreated phosphogypsum with calcium hydroxide slurry before adding solid waste fly ash, followed by static curing to obtain harmless phosphogypsum.

[0013] First, nano-Fe3O4 is reacted with γ-methacryloxypropyltrimethoxysilane to obtain modified magnetic particles, which are then reacted with acrylamide to prepare a flocculant. The modified magnetic particles in the flocculant not only provide magnetic separation function, which facilitates the recycling and reuse of the flocculant and reduces costs, but also contain active groups on their surface, which can more effectively adsorb heavy metal ions and soluble phosphates in phosphogypsum, thereby enhancing the flocculation effect and the removal efficiency of pollutants.

[0014] Secondly, adjusting the pH value to an alkaline environment by using calcium hydroxide slurry can promote the formation of hydroxide precipitates from heavy metal ions in phosphogypsum and facilitate the flocculant's coagulation effect, thereby achieving effective fixation of harmful substances. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1: A process and method for harmlessly treating phosphogypsum includes the following steps: (1) An ethanol solution was prepared by mixing anhydrous ethanol and deionized water at a volume ratio of 4:1; nano Fe3O4, ethanol solution and γ-methacryloyloxypropyltrimethoxysilane were mixed, the pH was adjusted to 5 with glacial acetic acid, the mixture was allowed to stand for 1 h, sonicated for 10 min, stirred at 550 r / min for 1.5 h at 45 °C, filtered, and the filter residue was washed 3 times with deionized water and anhydrous ethanol respectively, and dried under vacuum at 60 °C for 4 h to obtain modified magnetic particles. (2) The modified magnetic particles and deionized water were mixed at a mass ratio of 1:6 and ultrasonically dispersed to obtain a modified magnetic particle suspension; 72% acrylamide, EDTA and deionized water were mixed at a mass ratio of 1:0.02:10, nitrogen gas was introduced and the mixture was reacted at 65°C for 30 min, ammonium persulfate / sodium bisulfite initiator was added and the reaction was continued for 5.5 h, washed three times with anhydrous ethanol and vacuum dried at 60°C to obtain a stabilizer; acrylamide, acryloyloxyethyltrimethylammonium chloride ammonium sulfate, stabilizer and deionized water were mixed at a mass ratio of 1:0.2:0.1:10, nitrogen gas was introduced and the mixture was reacted at 25°C for 40 min, the modified magnetic particle suspension was added and the reaction was continued for 10 min, ammonium persulfate / sodium bisulfite initiator was added and the reaction was continued for 22 h, the mixture was filtered, and the filter residue was washed three times with 50% ethanol solution and acetone respectively, and vacuum dried at 60°C for 4 h to obtain a flocculant; (3) The phosphogypsum is crushed and sieved to a particle size of less than 2 mm to obtain pretreated phosphogypsum; flocculant and deionized water are mixed at a mass ratio of 1:200 to prepare flocculant solution; calcium oxide and deionized water are mixed at a mass ratio of 1:10 to prepare calcium hydroxide slurry; flocculant solution and pretreated phosphogypsum are mixed at a mass ratio of 1:30, stirred for 20 min, calcium hydroxide slurry is added, pH is adjusted to 10, stirring is continued for 40 min, solid waste fly ash with a mass ratio of 0.1 times that of pretreated phosphogypsum is added, stirred evenly and left to stand for 1 day, and cured at 20℃ and 60% humidity for 1 week to obtain the final product.

[0017] Example 2: A process and method for harmlessly treating phosphogypsum includes the following steps: (1) An ethanol solution was prepared by mixing anhydrous ethanol and deionized water at a volume ratio of 4:1; nano Fe3O4, ethanol solution and γ-methacryloyloxypropyltrimethoxysilane were mixed, the pH was adjusted to 5.25 with glacial acetic acid, the mixture was allowed to stand for 1 h, sonicated for 15 min, stirred at 600 r / min for 2 h at 50 °C, filtered, and the filter residue was washed 4 times with deionized water and anhydrous ethanol respectively, and dried under vacuum at 60 °C for 5 h to obtain modified magnetic particles; (2) The modified magnetic particles and deionized water were mixed at a mass ratio of 1:6 and ultrasonically dispersed to obtain a modified magnetic particle suspension; 72% acrylamide, EDTA and deionized water were mixed at a mass ratio of 1:0.02:10, nitrogen gas was introduced and the mixture was reacted at 65°C for 30 min, ammonium persulfate / sodium bisulfite initiator was added and the reaction was continued for 6 h, washed 4 times with anhydrous ethanol and vacuum dried at 60°C to obtain a stabilizer; acrylamide, acryloyloxyethyltrimethylammonium chloride ammonium sulfate, stabilizer and deionized water were mixed at a mass ratio of 1:0.2:0.1:10, nitrogen gas was introduced and the mixture was reacted at 30°C for 50 min, the modified magnetic particle suspension was added and the reaction was continued for 15 min, ammonium persulfate / sodium bisulfite initiator was added and the reaction was continued for 24 h, the mixture was filtered, and the filter residue was washed 4 times with 50% ethanol solution and acetone respectively, and vacuum dried at 60°C for 5 h to obtain a flocculant; (3) Crush and sieve the phosphogypsum to obtain pretreated phosphogypsum; mix the flocculant and deionized water at a mass ratio of 1:250 to prepare a flocculant solution; mix the calcium oxide and deionized water at a mass ratio of 1:15 to prepare a calcium hydroxide slurry; mix the flocculant solution and pretreated phosphogypsum at a mass ratio of 1:35, stir for 25 minutes, add the calcium hydroxide slurry, adjust the pH to 11, continue stirring for 50 minutes, add 0.15 times the mass of solid waste fly ash of the pretreated phosphogypsum, stir evenly, let stand for 2 days, and cure at 30℃ and 70% humidity for one week to obtain the final product.

[0018] Example 3: A process and method for harmlessly treating phosphogypsum includes the following steps: (1) An ethanol solution was prepared by mixing anhydrous ethanol and deionized water at a volume ratio of 4:1; nano Fe3O4, ethanol solution and γ-methacryloxypropyltrimethoxysilane were mixed, the pH was adjusted to 5.5 with glacial acetic acid, let stand for 1 h, sonicate for 20 min, stir at 55℃ and 650 r / min for 2.5 h, filter, wash the filter residue with deionized water and anhydrous ethanol 5 times respectively, and vacuum dry at 60℃ for 6 h to obtain modified magnetic particles; (2) The modified magnetic particles and deionized water were mixed at a mass ratio of 1:6 and ultrasonically dispersed to obtain a modified magnetic particle suspension; 72% acrylamide, EDTA and deionized water were mixed at a mass ratio of 1:0.02:10, nitrogen gas was introduced and the mixture was reacted at 65°C for 30 min, ammonium persulfate / sodium bisulfite initiator was added and the reaction was continued for 6.5 h, washed 5 times with anhydrous ethanol and vacuum dried at 60°C to obtain a stabilizer; acrylamide, acryloyloxyethyltrimethylammonium chloride ammonium sulfate, stabilizer and deionized water were mixed at a mass ratio of 1:0.2:0.1:10, nitrogen gas was introduced and the mixture was reacted at 35°C for 60 min, the modified magnetic particle suspension was added and the reaction was continued for 20 min, ammonium persulfate / sodium bisulfite initiator was added and the reaction was continued for 26 h, the mixture was filtered, and the filter residue was washed 5 times with 50% ethanol solution and acetone respectively, and vacuum dried at 60°C for 6 h to obtain a flocculant; (3) Crush and sieve the phosphogypsum to a particle size of less than 2 mm to obtain pretreated phosphogypsum; mix flocculant and deionized water at a mass ratio of 1:300 to prepare flocculant solution; mix calcium oxide and deionized water at a mass ratio of 1:20 to prepare calcium hydroxide slurry; mix flocculant solution and pretreated phosphogypsum at a mass ratio of 1:40, stir for 30 min, add calcium hydroxide slurry, adjust pH to 12, continue stirring for 60 min, add solid waste fly ash at a mass ratio of 0.2 times that of pretreated phosphogypsum, stir evenly, let stand for 3 days, and cure at 40℃ and 80% humidity for one week to obtain the final product.

[0019] Comparative Example 1: A process and method for harmlessly treating phosphogypsum includes the following steps: The phosphogypsum was crushed and sieved to a particle size of less than 2 mm to obtain pretreated phosphogypsum. The pretreated phosphogypsum and deionized water were mixed at a mass ratio of 1:20 and stirred for 25 min. Calcium hydroxide slurry was added to adjust the pH to 11, and stirring was continued for 50 min. Solid waste fly ash with a mass of 0.15 times that of the pretreated phosphogypsum was added, stirred evenly, and allowed to stand for 2 days. It was then cured at 30℃ and 70% humidity for one week to obtain the final product.

[0020] Test Example 1: Phosphorus removal rate test: The soluble phosphorus removal rate of the samples prepared in each example and comparative example was tested according to JC / T2073-2011 "Determination of Phosphorus and Fluorine in Phosphogypsum". The results are shown in Table 1.

[0021] Table 1

[0022] A comparison of the experimental data from Examples 1-3 and Comparative Example 1 in Table 1 reveals that the harmless treatment process and method for phosphogypsum described in this invention can effectively fix soluble phosphorus.

[0023] By comparison, the soluble phosphorus removal rate of Examples 1-3 was greater than that of Comparative Example 1. This indicates that the modified magnetic particles prepared by reacting nano Fe3O4 with γ-methacryloxypropyltrimethoxysilane, and then reacting with acrylamide to prepare flocculants, not only provide magnetic separation function, facilitating the recycling and reuse of flocculants and reducing costs, but also contain active groups on their surface, which can more effectively adsorb heavy metal ions and soluble phosphates in phosphogypsum, thereby enhancing the removal efficiency of pollutants. Adjusting the pH value to an alkaline environment by using calcium hydroxide slurry can promote the formation of hydroxide precipitates of heavy metal ions in phosphogypsum and facilitate the flocculant to exert its coagulation effect, thereby achieving effective fixation of harmful substances.

[0024] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process and method for harmlessly treating phosphogypsum, characterized in that, The process for harmless treatment of phosphogypsum involves crushing and screening phosphogypsum to obtain pretreated phosphogypsum; then adding flocculant and pretreated phosphogypsum to solid waste fly ash after adjusting the pH with calcium hydroxide slurry, and allowing it to stand for curing to obtain harmless phosphogypsum. The flocculant is prepared by reacting nano-Fe3O4 with γ-methacryloxypropyltrimethoxysilane to obtain modified magnetic particles; and by adding acrylamide to the modified magnetic particles after polymerization initiated by an initiator.

2. The process and method for harmless treatment of phosphogypsum according to claim 1, characterized in that, The preparation steps of the harmless phosphogypsum are as follows: (1) Mix nano Fe3O4, ethanol solution and γ-methacryloxypropyltrimethoxysilane, adjust the pH to 5~5.5 with glacial acetic acid, let stand for 1 h, sonicate for 10~20 min, stir at 550~650 r / min for 1.5~2.5 h at 45~55℃, filter, wash the filter residue with deionized water and anhydrous ethanol 3~5 times respectively, and vacuum dry at 60℃ for 4~6 h to obtain modified magnetic particles; (2) Acrylamide, acryloyloxyethyltrimethylammonium chloride ammonium sulfate, stabilizer and deionized water are mixed in a mass ratio of 1:0.2:0.1:10, nitrogen gas is introduced, and the mixture is reacted at 25~35℃ for 40~60 min. Modified magnetic particle suspension is added, and the mixture is reacted for another 10~20 min. Ammonium persulfate / sodium bisulfite initiator is added, and the mixture is reacted for another 22~26 h. The mixture is filtered, and the filter residue is washed 3~5 times with 50% ethanol solution and acetone respectively. The residue is then vacuum dried at 60℃ for 4~6 h to obtain flocculant. (3) Mix the flocculant solution and pretreated phosphogypsum at a mass ratio of 1: (30~40), stir for 20~30 min, add calcium hydroxide slurry, adjust the pH to 10~12, continue stirring for 40~60 min, add solid waste fly ash at a mass ratio of 0.1~0.2 times that of pretreated phosphogypsum, stir evenly, let stand for 1~3 days, and cure at 20~40℃ and 60%~80% humidity for one week to obtain the product.

3. The preparation steps of the harmless phosphogypsum according to claim 2, characterized in that, The method for preparing the ethanol solution in step (1) is as follows: anhydrous ethanol and deionized water are mixed at a volume ratio of 4:

1.

4. The preparation steps of the harmless phosphogypsum according to claim 2, characterized in that, The modified magnetic particle suspension in step (2) is prepared by mixing the modified magnetic particles and deionized water at a mass ratio of 1:6, followed by ultrasonic dispersion.

5. The preparation steps of the harmless phosphogypsum according to claim 2, characterized in that, The stabilizer in step (2) is prepared by mixing 72% acrylamide, EDTA and deionized water at a mass ratio of 1:0.02:10, passing nitrogen gas through the mixture, reacting at 65°C for 30 min, adding ammonium persulfate / sodium bisulfite initiator and continuing the reaction for 5.5~6.5 h, washing with anhydrous ethanol 3~5 times, and vacuum drying at 60°C.

6. The preparation steps of the harmless phosphogypsum according to claim 2, characterized in that, The preparation method of the flocculant solution in step (3) is as follows: flocculant and deionized water are mixed at a mass ratio of 1: (200~300) to obtain the solution.

7. The preparation steps of the harmless phosphogypsum according to claim 2, characterized in that, The preparation method of the pretreated phosphogypsum in step (3) is as follows: crush the phosphogypsum and sieve it to a particle size of less than 2 mm to obtain the phosphogypsum.

8. The preparation steps of the harmless phosphogypsum according to claim 2, characterized in that, The calcium hydroxide slurry in step (3) is prepared by mixing calcium oxide and deionized water at a mass ratio of 1: (10~20).

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