Green treatment method of phosphogypsum

Abstract

The invention discloses a green treatment method of ardealite. The green treatment method comprises the following steps: S1, pretreatment of ardealite; s2, carrying out micro-bubble flotation; s3, impurity ions are removed; according to the method, the collecting agent can be used for carrying out surface modification on the microbubbles, and then the modified bubbles with the targeted adsorption function are obtained, so that the microbubbles are likely to be selectively adhered to impurities, and the impurity removal effect on the ardealite mixed liquid is enhanced.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection technologies, and particularly to a green disposal method for phosphogypsum. Background Art

[0002] Phosphogypsum is a by-product generated during the production of phosphoric acid. Its main source is the calcium sulfate precipitate formed when phosphate rock reacts with sulfuric acid to prepare phosphoric acid. This precipitate forms phosphogypsum after filtration and washing, and usually contains impurities such as a certain amount of moisture, unreacted phosphate rock, fluorides, heavy metals, and radioactive elements.

[0003] At present, the large amount of phosphogypsum produced has led to its long-term and large-scale accumulation, becoming a major source of environmental problems. The long-term and large-scale accumulation of phosphogypsum will cause a series of environmental and safety problems. Moreover, compared with ordinary gypsum, phosphogypsum contains more impurities, such as phosphoric acid and its salt impurities, fluoride impurities, organic impurities, SiO 2 as well as some heavy metal ions, radioactive elements, etc. This makes phosphogypsum have poor water resistance, and its whiteness and hardness are inferior to those of gypsum in many aspects, greatly limiting its application fields and making it difficult to achieve resource utilization. In response to this hot issue, enterprises at home and abroad have conducted long-term research, but this global problem has still not been solved. Especially in China's phosphochemical industry, there are currently many problems such as a large stockpile of phosphogypsum that is still growing rapidly, and the low added value of the products after processing phosphogypsum. In addition, the existing phosphogypsum technologies face high costs and heavy pollution. For example, the water washing method consumes a large amount of water resources, and the wastewater after washing is still difficult to treat; the thermal method faces problems such as high risk and high energy consumption. Therefore, it is necessary to develop a green disposal process to realize the resource utilization of phosphogypsum without polluting the environment.

[0004] At present, the pretreatment methods for purifying and removing impurities from phosphogypsum mainly include lime neutralization method, water washing method, flotation method, acid leaching method, calcination method, screening method, etc. These impurity removal and purification pretreatment methods have their own advantages and disadvantages. Both the lime neutralization method and the water washing method are effective methods for removing water-soluble phosphorus and water-soluble fluorine in phosphogypsum. The lime neutralization method has the characteristics of simple process and small investment cost, and is widely used in actual applications. The water washing method is simple to operate and has remarkable impurity removal effect, but it has high investment cost, large amount of washing water, and high energy consumption. Generally, when the phosphogypsum treatment scale exceeds 100,000 t / a, it is economically competitive. The flotation method is suitable for treating phosphogypsum with a high quartz content, and the high-quality phosphogypsum after treatment can be used to prepare downstream high-value products. Through the investigation of the current situation of phosphogypsum in China in the past two years, it is understood that the current utilization ways of phosphogypsum produced by enterprises are mainly to prepare building materials products such as cement retarders and building gypsum powder, with low product value and small sales radius. Therefore, the pretreatment means generally adopted by enterprises is mainly the low-cost lime stacking treatment process, but there are problems such as large floor area, long stacking reaction time, and pollution of the surrounding environment. Summary of the Invention

[0005] To solve the above problems, the present invention provides a green disposal method for phosphogypsum.

[0006] A green disposal method for phosphogypsum includes the following steps:

[0007] S1. Pretreatment of phosphogypsum;

[0008] Crush and grind the phosphogypsum, then pass it through a 200-mesh sieve to obtain phosphogypsum powder. Mix the phosphogypsum powder with water to form a slurry with a mass concentration of 20 - 40%, and adjust the pH value of the slurry to 5 - 8.

[0009] S2. Microbubble flotation;

[0010] Add a collector to the microbubble generator. Subsequently, the microbubble generator produces modified microbubbles modified by the collector. Then, stir the slurry and the modified microbubbles in a flotation cell, and then perform flotation to form a foam layer composed of microbubbles and impurities, a phosphogypsum layer after impurity removal, and a liquid layer after impurity removal. Recover the foam layer composed of microbubbles and impurities and the phosphogypsum layer after impurity removal, and perform the next treatment on the liquid layer after impurity removal;

[0011] Among them, the addition amount of the collector is: 1 - 2 g of the collector is added to each liter of the working liquid of the microbubble generator; the stirring speed is 1200 - 1500 rpm, the stirring time is 20 - 25 min, the gas flow rate of the microbubble generator is 0.4 - 0.6 m 3 / min, and the diameter of the modified microbubbles is 1 - 50 μm;

[0012] S3. Removal of impurity ions;

[0013] Pass the liquid layer after impurity removal through an exchange column filled with styrene anion exchange resin for adsorption treatment. The adsorption treatment time is 1 - 2 h, and the treatment is completed. Among them, the feeding speed of the liquid layer after impurity removal is 5 - 10 BV / h.

[0014] Note: Through the above method, collectors can be used to surface-modify microbubbles to obtain modified microbubbles with targeted adsorption functions, so that microbubbles are prone to selectively adhere to impurities (such as siliceous substances), thereby enhancing the impurity removal effect of the phosphogypsum mixture. Specifically, by adding effective groups in the collector, such as COOH branches, the surface physical and chemical properties of both the bubbles and siliceous impurities can be changed simultaneously during adsorption.

[0015] Furthermore, the collector is sodium oleate.

[0016] Description: As an ionic collector, sodium oleate has high collecting efficiency and selectivity. In the phosphogypsum mixture, sodium oleate can adsorb with specific impurity ions, thus achieving effective separation of impurities from phosphogypsum. This ability of selective separation helps reduce the loss of useful components and improve the purity of phosphogypsum.

[0017] Furthermore, the working liquid of the microbubble generator is water or a surfactant.

[0018] Description: In the working liquid of the microbubble generator, using water as the working liquid will not cause environmental pollution. When mixed with a surfactant, it can regulate the generation and properties of bubbles to meet different application requirements.

[0019] Furthermore, the collector is modified sodium oleate, and the preparation method of the modified sodium oleate includes:

[0020] S2-1. Introduce a branched chain on the carbon chain of the sodium oleate to obtain branched-chain sodium oleate;

[0021] S2-2. Perform a quaternization reaction on a long-chain fatty amine and dimethyl sulfate to prepare a long-chain quaternary ammonium salt;

[0022] S2-3. Mix and stir the branched-chain sodium oleate and the long-chain quaternary ammonium salt in a mass ratio of 1-2:1 to obtain modified sodium oleate.

[0023] Description: By using the microbubbles attached with sodium oleate obtained by the above method to float the phosphogypsum mixture, compared with directly adding sodium oleate alone or using microbubbles alone, the flotation efficiency can be improved. As a collector, sodium oleate can selectively adsorb on specific impurities in the phosphogypsum mixture; the microbubbles serve as carriers and can carry the impurities collected by sodium oleate to float to the liquid surface. The modified microbubbles are more likely to selectively adhere to the impurities, thus achieving separation. Due to the strong surface activity of the long-chain quaternary ammonium salt, it can form a firm adsorption layer on the mineral surface and have a synergistic effect with the above-mentioned modified microbubbles. This synergistic effect makes the flotation process more efficient, improves the collecting efficiency, and can significantly increase the removal rate of impurities.

[0024] Furthermore, the branched chain in S2-1 is COOH.

[0025] Description: The above-mentioned COOH belongs to a hydrophilic group, which helps to bond with the mineral, thus strengthening its targeted adsorption on the surface of the target mineral and improving the collecting effect.

[0026] Furthermore, the method of introducing a branched chain on the carbon chain of the sodium oleate to obtain branched-chain sodium oleate is:

[0027] Weigh oleic acid and maleic anhydride in a molar ratio of 7:1, and then add a catalyst accounting for 0.2 - 0.8 wt% of maleic anhydride. Under nitrogen protection, slowly heat up to 60 - 70 °C, keep the temperature constant and continuously stir for reaction for 4 - 6 h. After the reaction is completed, an addition product is obtained;

[0028] Add an aqueous sodium hydroxide solution with a mass fraction of 10 - 20% to the addition product in a volume ratio of 1:3 - 4; at a temperature of 80 - 90 °C, carry out a saponification reaction, continuously stir for 2 - 3 h, cool to room temperature, and then carry out solid-liquid separation and drying to obtain sodium oleate with branched chains.

[0029] Note: One end of the sodium oleate molecule obtained above has a hydrophilic carboxylate group, and the other end is a hydrophobic long carbon chain. This unique "amphiphilic" structure enables microbubbles to have the function of targeted adsorption.

[0030] Furthermore, the method for preparing a long-chain quaternary ammonium salt by quaternizing a long-chain fatty amine with dimethyl sulfate is as follows: Take dodecylamine and dimethyl sulfate in a ratio of 50 g:30 g; then heat dodecylamine from room temperature to 50 - 55 °C under stirring, and then dropwise add dimethyl sulfate, controlling the dropping rate to keep the reaction temperature at 50 - 60 °C; after the dropping is completed, keep stirring at a constant temperature for reaction for 3 - 5 h. After the reaction is completed, a long-chain quaternary ammonium salt is obtained.

[0031] Note: The long-chain quaternary ammonium salt prepared by the above method has high surface activity and hydrophobic properties. When the modified sodium oleate is used in combination with the long-chain quaternary ammonium salt, the long carbon chain and branched-chain structure in the modified sodium oleate may interact with the long-chain quaternary ammonium salt, resulting in a synergistic effect that can improve surface activity, enhance bactericidal performance, and improve solubility, etc.

[0032] Furthermore, the styrene anion exchange resin contains a quaternary ammonium salt.

[0033] Note: The styrene anion exchange resin containing a quaternary ammonium salt can improve the ion exchange capacity of the resin, and the resin has good chemical stability, enhanced mechanical strength, and wide applicability.

[0034] Furthermore, the preparation method of the styrene anion exchange resin is as follows:

[0035] S3-1: Take water, gelatin, and sodium phosphate in a mass ratio of 100 - 120:1:2 - 3, and mix them. Stir at 45 - 55 °C for 1 - 2 h to obtain an aqueous phase;

[0036] S3-2: Take styrene, divinylbenzene, benzoyl peroxide, and a pore-forming agent in a mass ratio of 15 - 20:10:0.1:25 - 30 and mix them evenly to obtain an oil phase;

[0037] S3-3. Take the aqueous phase and the oil phase in a mass ratio of 2-3:1. First, stir the aqueous phase and heat it to 60-65 °C, then add the oil phase, continue to heat to 80-85 °C, then stir for 15-20 min, then heat to 90-94 °C and stir for 8-10 min, cool to 85-87 °C and stir for 4-6 min, and then heat to 95-99 °C and stir for 15-20 min to obtain a pretreated polymer.

[0038] S3-4. Take the pretreated polymer, dichloroethane, and N,N-dimethylhexadecylamine in a mass ratio of 10-13:50-55:2, then mix them, and stir and react at a temperature of 95-99 °C for 8-11 h to obtain a styrene anion exchange resin.

[0039] Note: The above method introduces quaternary ammonium salt groups into the styrene anion exchange resin, which can significantly improve the ion exchange capacity and selectivity of the resin. This efficient ion exchange ability enables the resin to quickly and accurately capture and remove these harmful ions, such as nitrates, sulfates, and some organic acid radicals, when treating water bodies containing high concentrations of anions, thereby effectively purifying the water quality.

[0040] The beneficial effects of the present invention are as follows:

[0041] The present invention can use a collector to perform surface modification on microbubbles to obtain modified bubbles with targeted adsorption functions, so that the microbubbles are easy to selectively adhere to impurities (such as siliceous substances), thereby enhancing the impurity removal effect on the phosphogypsum mixture. Specifically, by adding effective groups, such as COOH branches, in the collector, the surface physical and chemical properties of both the bubbles and the siliceous impurities can be changed simultaneously during adsorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the principle of modified microbubble flotation in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] To further illustrate the methods and effects adopted by the present invention, the technical solutions of the present invention will be clearly and completely described below in combination with experiments.

[0044] Example 1: A green disposal method for phosphogypsum, comprising the following steps:

[0045] S1. Pretreatment of phosphogypsum;

[0046] Crush and grind the phosphogypsum, then pass it through a 200-mesh sieve to obtain phosphogypsum powder. Mix the phosphogypsum powder with water to form a slurry with a mass concentration of 30%, and adjust the pH value of the slurry to 7.

[0047] S2. Microbubble flotation;

[0048] Add a collector to the microbubble generator. Subsequently, the microbubble generator produces modified microbubbles modified by the collector. Then, stir the slurry and the modified microbubbles in a flotation cell, and then perform flotation to form a foam layer composed of microbubbles and impurities, a phosphogypsum layer after impurity removal, and a liquid layer after impurity removal. Recover the foam layer composed of microbubbles and impurities and the phosphogypsum layer after impurity removal, and perform further treatment on the liquid layer after impurity removal;

[0049] Among them, the addition amount of the collector is: add 1.5 g of the collector to each liter of the working liquid of the microbubble generator; the stirring speed is 1300 rpm, the stirring time is 23 min, the gas flow rate of the microbubble generator is 0.5 m 3 / min, and the diameter of the modified microbubbles is 10 μm;

[0050] The collector is sodium oleate; the working liquid of the microbubble generator is water;

[0051] The collector is modified sodium oleate, and the preparation method of the modified sodium oleate includes:

[0052] S2-1. Introduce a branched chain on the carbon chain of sodium oleate to obtain branched-chain sodium oleate;

[0053] S2-2. Perform a quaternization reaction on a long-chain fatty amine and dimethyl sulfate to prepare a long-chain quaternary ammonium salt;

[0054] S2-3. Mix and stir the branched-chain sodium oleate and the long-chain quaternary ammonium salt in a mass ratio of 1.5:1 to obtain modified sodium oleate.

[0055] The branched chain is COOH; the method for introducing a branched chain on the carbon chain of sodium oleate to obtain branched-chain sodium oleate is:

[0056] Weigh oleic acid and maleic anhydride in a molar ratio of 7:1, then add a catalyst accounting for 0.5 wt% of maleic anhydride. Under nitrogen protection, slowly heat up to 65 °C, keep the temperature constant and continuously stir and react for 5 h. After the reaction is completed, an addition product is obtained;

[0057] Add an aqueous sodium hydroxide solution with a mass fraction of 15% to the addition product in a volume ratio of 1:3.5; at a temperature of 85 °C, perform a saponification reaction, continuously stir for 2.5 h, cool to room temperature, and then perform solid-liquid separation and drying to obtain branched-chain sodium oleate;

[0058] The method for preparing a long-chain quaternary ammonium salt by quaternizing a long-chain fatty amine with dimethyl sulfate is as follows: Take dodecylamine and dimethyl sulfate in a ratio of 50 g:30 g; then heat the dodecylamine from room temperature to 52 °C with stirring, and then add dropwise dimethyl sulfate while controlling the dropping rate to keep the reaction temperature at 55 °C; after the dropping is complete, stir the reaction mixture at a constant temperature for 4 h to complete the reaction and obtain the long-chain quaternary ammonium salt;

[0059] S3. Remove impurity ions;

[0060] Pass the liquid layer after impurity removal through an exchange column filled with styrene anion exchange resin for adsorption treatment for 1.5 h to complete the treatment, where the feeding rate of the liquid layer after impurity removal is 7 BV / h;

[0061] The styrene anion exchange resin contains quaternary ammonium salt, and the preparation method of the styrene anion exchange resin is as follows:

[0062] S3-1. Take water, gelatin, and sodium phosphate in a mass ratio of 110:1:2.5, mix them, and stir at 50 °C for 1.5 h to obtain an aqueous phase;

[0063] S3-2. Take styrene, divinylbenzene, benzoyl peroxide, and a pore-forming agent in a mass ratio of 18:10:0.1:28, mix them evenly to obtain an oil phase;

[0064] S3-3. Take the aqueous phase and the oil phase in a mass ratio of 2.5:1. First, stir the aqueous phase and heat it to 63 °C, then add the oil phase, continue to heat to 83 °C, then stir for 18 min, then heat to 90 - 94 °C and stir for 8 - 10 min, cool to 86 °C and stir for 5 min, and then heat to 97 °C and stir for 18 min to obtain a pretreated polymer;

[0065] S3-4. Take the pretreated polymer, dichloroethane, and N,N-dimethylhexadecylamine in a mass ratio of 12:52:2, then mix them, and stir and react at a temperature of 95 - 99 °C for 9 h to obtain the styrene anion exchange resin.

[0066] Example 2: The difference between this example and Example 1 lies in the different treatment parameters in S1. Mix the phosphogypsum powder with water to form a slurry with a mass concentration of 40%, and adjust the pH value of the slurry to 5.

[0067] Example 3: The difference between this example and Example 1 lies in the different treatment parameters in S1. Mix the phosphogypsum powder with water to form a slurry with a mass concentration of 20%, and adjust the pH value of the slurry to 8.

[0068] Example 4: The difference between this example and Example 1 lies in the processing parameters in S2. The addition amount of the collector is: 1 g of the collector is added to the working liquid of each liter of the microbubble generator; the stirring speed is 1200 rpm, the stirring time is 25 min, the gas flow rate of the microbubble generator is 0.6 m 3 / min, and the diameter of the modified microbubbles is 50 μm.

[0069] Example 5: The difference between this example and Example 1 lies in the processing parameters in S2. The addition amount of the collector is: 2 g of the collector is added to the working liquid of each liter of the microbubble generator; the stirring speed is 1500 rpm, the stirring time is 20 min, the gas flow rate of the microbubble generator is 0.4 m 3 / min, and the diameter of the modified microbubbles is 1 μm.

[0070] Example 6: The difference between this example and Example 1 lies in the processing parameters in S3. The liquid layer after impurity removal is passed into an exchange column of styrene anion exchange resin for adsorption treatment. The adsorption treatment time is 1 h, and the treatment is completed. Among them, the feeding speed of the liquid layer after impurity removal is 10 BV / h.

[0071] Example 7: The difference between this example and Example 1 lies in the processing parameters in S3. The liquid layer after impurity removal is passed into an exchange column of styrene anion exchange resin for adsorption treatment. The adsorption treatment time is 2 h, and the treatment is completed. Among them, the feeding speed of the liquid layer after impurity removal is 5 BV / h.

[0072] Example 8: The difference between this example and Example 1 lies in the preparation parameters of the modified sodium oleate. The branched-chain sodium oleate and the long-chain quaternary ammonium salt are mixed and stirred in a mass ratio of 1:1 to obtain the modified sodium oleate.

[0073] Example 9: The difference between this example and Example 1 lies in the preparation parameters of the modified sodium oleate. The branched-chain sodium oleate and the long-chain quaternary ammonium salt are mixed and stirred in a mass ratio of 2:1 to obtain the modified sodium oleate.

[0074] Example 10: The difference between this example and Example 1 lies in the preparation parameters of the branched-chain sodium oleate. The method is as follows: Oleic acid and maleic anhydride are weighed in a molar ratio of 7:1, and then a catalyst accounting for 0.2 wt% of maleic anhydride is added. Under nitrogen protection, the temperature is slowly raised to 60 °C, and the reaction is carried out at a constant temperature with continuous stirring for 6 h. After the reaction is completed, an addition product is obtained;

[0075] Add an aqueous sodium hydroxide solution with a mass fraction of 20% to the addition product in a volume ratio of 1:3; carry out a saponification reaction at a temperature of 80 °C, continuously stir for 2 h, cool to room temperature, and then carry out solid-liquid separation and drying to obtain branched sodium oleate.

[0076] Example 11: The difference between this example and Example 1 is that the preparation parameters of the branched sodium oleate are different. The method is as follows: Weigh oleic acid and maleic anhydride in a molar ratio of 7:1, and then add a catalyst accounting for 0.8 wt% of maleic anhydride. Under nitrogen protection, slowly heat up to 70 °C, keep the temperature constant and continuously stir and react for 4 h. After the reaction is completed, an addition product is obtained;

[0077] Add an aqueous sodium hydroxide solution with a mass fraction of 10% to the addition product in a volume ratio of 1:4; carry out a saponification reaction at a temperature of 90 °C, continuously stir for 3 h, cool to room temperature, and then carry out solid-liquid separation and drying to obtain branched sodium oleate.

[0078] Example 12: The difference between this example and Example 1 is that the preparation parameters of the long-chain quaternary ammonium salt are different. The method is as follows: Take dodecylamine and dimethyl sulfate in a ratio of 50 g:30 g; then heat dodecylamine from room temperature to 55 °C under stirring, and then dropwise add dimethyl sulfate, controlling the dropping rate to keep the reaction temperature at 60 °C; after the dropping is completed, keep stirring and reacting at a constant temperature for 3 h. After the reaction is completed, a long-chain quaternary ammonium salt is obtained.

[0079] Example 13: The difference between this example and Example 1 is that the preparation parameters of the long-chain quaternary ammonium salt are different. The method is as follows: Take dodecylamine and dimethyl sulfate in a ratio of 50 g:30 g; then heat dodecylamine from room temperature to 50 °C under stirring, and then dropwise add dimethyl sulfate, controlling the dropping rate to keep the reaction temperature at 50 °C; after the dropping is completed, keep stirring and reacting at a constant temperature for 5 h. After the reaction is completed, a long-chain quaternary ammonium salt is obtained.

[0080] Example 14: The difference between this example and Example 1 is that the preparation parameters of the styrene anion exchange resin are different. The method is as follows: S3-1: Take water, gelatin and sodium phosphate in a mass ratio of 100:1:3, mix them, and stir at 45 °C for 1 h to obtain an aqueous phase;

[0081] S3-2: Take styrene, divinylbenzene, benzoyl peroxide and a pore-forming agent in a mass ratio of 15:10:0.1:25, mix them evenly to obtain an oil phase;

[0082] S3-3: Take the aqueous phase and the oil phase in a mass ratio of 2:1. First, stir the aqueous phase and heat it to 60 °C, then add the oil phase. After continuing to heat to 85 °C, stir for 20 min, then heat to 90 °C and stir for 8 min, cool to 85 °C and stir for 4 min, and then heat to 95 °C and stir for 15 min to obtain a pretreated polymer.

[0083] S3-4: Take the pretreated polymer, dichloroethane, and N,N-dimethylhexadecylamine in a mass ratio of 10:50:2, then mix them and stir and react at a temperature of 95 °C for 8 h to obtain a styrene anion exchange resin.

[0084] Example 15: The difference between this example and Example 1 lies in the different preparation parameters of the styrene anion exchange resin. The method is as follows: S3-1: Take water, gelatin, and sodium phosphate in a mass ratio of 120:1:2, mix them, and stir at 55 °C for 2 h to obtain an aqueous phase.

[0085] S3-2: Take styrene, divinylbenzene, benzoyl peroxide, and a pore-forming agent in a mass ratio of 20:10:0.1:30 and mix them evenly to obtain an oil phase.

[0086] S3-3: Take the aqueous phase and the oil phase in a mass ratio of 3:1. First, stir the aqueous phase and heat it to 65 °C, then add the oil phase. After continuing to heat to 80 °C, stir for 15 min, then heat to 94 °C and stir for 10 min, cool to 87 °C and stir for 6 min, and then heat to 99 °C and stir for 20 min to obtain a pretreated polymer.

[0087] S3-4: Take the pretreated polymer, dichloroethane, and N,N-dimethylhexadecylamine in a mass ratio of 13:55:2, then mix them and stir and react at a temperature of 99 °C for 11 h to obtain a styrene anion exchange resin.

[0088] Example 16: The difference between this example and Example 1 lies in that the working liquid of the microbubble generator is a surfactant.

[0089] Experimental example: The description basis of this experimental example is the recorded scheme in Example 1, aiming to clarify the actual application effect of the present invention.

[0090] 1. The methods of Examples 1 to 16 and Comparative Examples 1 to 5 were respectively used to treat phosphogypsum to obtain the removal rate of silicon impurities in phosphogypsum. Before treatment, the fluorine in the phosphogypsum exceeded the standard according to the index of GB / T 23456—2018 "Phosphogypsum". Before the S3 adsorption treatment, the fluorine content in the liquid layer after impurity removal was 4 - 5 mg / L (exceeding 1.0 mg / L, and 1.0 mg / L is the fluoride ion concentration harmful to the human body). After the adsorption treatment, it was found through experiments that the fluorine content in the phosphogypsum after the treatment of the examples of the present invention did not exceed the standard, but the fluorine content in Comparative Examples 1 and 2 exceeded the standard. This may be because the flotation treatment in Comparative Examples 1 and 2 was not thorough, and the fluorine in the phosphogypsum was not completely released into the liquid layer.

[0091] The results obtained are as follows:

[0092] 1. Explore the influence of different flotation methods on the impurity removal effect of phosphogypsum;

[0093] Comparative Example 1: The difference from Example 1 is that unmodified microbubbles were used for flotation.

[0094] Comparative Example 2: The difference from Example 1 is that the collector was directly added to the slurry obtained in S1, and unmodified microbubbles were used for flotation.

[0095] Comparative Example 3: The difference from Example 1 is that commercially available sodium oleate was used as the collector for microbubble modification and flotation.

[0096] Comparative Example 4: The difference from Example 1 is that sodium oleate and long-chain quaternary ammonium salts were not used in combination, and only sodium oleate was used as the collector.

[0097] Comparative Example 5: The difference from Example 1 is that commercially available styrene anion exchange resin was used.

[0098] Taking Example 1 and Comparative Examples 1 - 5 for comparison, as shown in Table 1,

[0099] Table 1 Experimental results of impurity removal of phosphogypsum by different treatment methods

[0100]

[0101] As can be seen from Table 1, by comparing Example 1 and Comparative Example 1, it can be seen that, as Figure 1As shown in the figure, in Example 1, by using modified microbubbles for flotation, the microbubbles have the function of targeted adsorption, exerting the conjugate induction effect of the collector, and improving the removal rate of impurities in the phosphogypsum mixed solution. In contrast, in Comparative Example 1, only the flotation function of microbubbles is used to adsorb impurities, and it is impossible to efficiently and specifically remove impurities in the mixed solution. Therefore, the method of using modified microbubbles in Example 1 is more preferable.

[0102] By comparing Example 1 with Comparative Example 2, it can be seen that compared with the method of directly adding a collector to the phosphogypsum mixed solution in Comparative Example 2, the impurity removal effect of attaching the collector to the microbubbles in Example 1 is more preferable. This may be because in Example 1, by attaching the collector to the surface of the microbubbles, the contact area and attachment strength between the microbubbles and the impurity objects can be enhanced, thereby improving the impurity removal effect. In Comparative Example 2, when the collector is directly added to the mixed solution, it may cause the collector to combine with the impurity objects, and the microbubbles float this complex. In this way, the direct adsorption effect of the microbubbles is reduced, resulting in a lower removal rate than in Example 1.

[0103] By comparing Example 1 with Comparative Example 3, it can be found that after using commercially available sodium oleate as a collector to modify and float the microbubbles in Comparative Example 3, the removal effect of impurities is not as good as that in Example 1. This may be because the existing technology in Comparative Example 3 did not improve sodium oleate, resulting in insufficient hydrophilic groups in sodium oleate. After adding branched chains in Example 1, the collector has a better collection effect on impurities, thereby improving the removal rate of impurities.

[0104] By comparing Example 1 with Comparative Example 4, it can be seen that in Example 1, by mixing and using branched-chain sodium oleate and long-chain quaternary ammonium salts, the collection effect can be further improved. The reason is that the mixing of sodium oleate and long-chain quaternary ammonium salts can form a synergistic effect, jointly improving the removal effect of impurities in the phosphogypsum mixed solution.

[0105] By comparing Example 1 with Comparative Example 5, it can be seen that using the styrene anion exchange resin prepared by the present invention in Example 1 has a good example treatment effect and can effectively adsorb polluting ions in the liquid. In Comparative Example 5, directly using the styrene anion exchange resin in the existing technology, its fluoride ion treatment effect needs to be improved. This may be because the preparation method in Example 1 can form a resin with a better structure and adsorption effect.

[0106] 2. Explore the influence of different parameters on the impurity removal effect of phosphogypsum;

[0107] Take Example 1, Examples 8 - 14, and Examples 17 - 18 for comparison, as shown in Table 2;

[0108] Table 2 Impurity Removal Effects of Phosphogypsum under Different Parameters

[0109] Parameter Silicon removal rate % Example 1 93.4 Example 4 92.0 Example 5 92.5 Example 6 92.7 Example 7 92.1 Example 8 91.9 Example 9 92.2 Example 10 91.6 Example 11 93.0 Example 12 92.8 Example 13 92.4 Example 14 93.1 Example 15 92.5

[0110] As can be seen from Table 2, by comparing Example 1, Example 4 and Example 5, it can be found that the microbubble treatment parameters of Example 1 are more preferable. This may be because the parameters of Example 1 are more applicable to the environment of the phosphogypsum mixture. By comparing Example 1, Example 6 and Example 7, it can be found that the adsorption treatment parameters of Example 1 are more preferable. By comparing Example 1, Example 8 and Example 9, it can be found that the ratio of sodium oleate to long-chain quaternary ammonium salt in Example 1 is more optimal. This may be because, under this ratio, sodium oleate and long-chain quaternary ammonium salt can better exert a synergistic effect and improve the impurity removal rate. By comparing Example 1, Example 10 and Example 11, it can be found that the preparation parameters of branched-chain sodium oleate in Example 1 are more preferable. By comparing Example 1, Example 12 and Example 13, it can be found that the preparation parameters of long-chain quaternary ammonium salt in Example 1 are more preferable. By comparing Example 1, Example 14 and Example 15, it can be found that the preparation parameters of styrene anion exchange resin in Example 1 are more preferable.

Claims

1. A green disposal method for phosphogypsum, characterized in that: The following steps are involved: S1, phosphogypsum pretreatment; The phosphogypsum is crushed and ground, and then passed through a 200-mesh sieve to obtain phosphogypsum powder, the phosphogypsum powder is mixed with water to form a slurry with a mass concentration of 20 to 40%, and the pH value of the slurry is adjusted to 5 to 8; S2, microbubble flotation; Adding a collector to a microbubble generator, the microbubble generator then produces modified microbubbles modified by the collector, stirring the slurry and the modified microbubbles in a flotation tank, and then flotation to form a foam layer composed of microbubbles and impurities, a phosphogypsum layer after impurities removal, and a liquid layer after impurities removal, recovering the foam layer composed of microbubbles and impurities and the phosphogypsum layer after impurities removal, and performing the next step of processing on the liquid layer after impurities removal; The amount of collector added is: 1-2 g of collector is added per liter of working liquid of the microbubble generator; the stirring speed is 1200-1500 rpm, the stirring time is 20-25 min, and the air flow rate of the microbubble generator is 0.4-0.6 m 3 / min, the diameter of the modified microbubbles is 1 to 50 μm; S3, remove impurity ions; The liquid layer after impurities removal is passed into an exchange column of styrene anion exchange resin for adsorption treatment. The adsorption treatment time is 1 to 2 hours, and the treatment is completed. The introduction rate of the liquid layer after impurities removal is 5 to 10 BV / h.

2. A green disposal method for phosphogypsum according to claim 1, characterized in that: The collector is sodium oleate.

3. A green disposal method for phosphogypsum according to claim 1, characterized in that: The working liquid of the microbubble generator is water or a surfactant.

4. A green disposal method for phosphogypsum according to claim 1, characterized in that: The collector is modified sodium oleate, and the preparation method of the modified sodium oleate comprises: S2-1, introducing a branch chain into the carbon chain of the sodium oleate to obtain sodium oleate with a branch chain; S2-2, quaternizing a long-chain fatty amine with dimethyl sulfate to prepare a long-chain quaternary ammonium salt; S2-3, mixing and stirring the branched sodium oleate and the long carbon chain quaternary ammonium salt in a mass ratio of 1 to 2:1 to obtain modified sodium oleate.

5. A green disposal method for phosphogypsum as claimed in claim 4, characterized in that: The side chain in S2-1 is COOH.

6. A green disposal method for phosphogypsum as claimed in claim 5, characterized in that: The method for introducing a branched chain into the carbon chain of the sodium oleate to obtain the branched sodium oleate is: Weigh oleic acid and maleic anhydride at a molar ratio of 7:1, then add a catalyst accounting for 0.2-0.8 wt% of maleic anhydride, slowly heat to 60-70°C under nitrogen protection, keep constant temperature and stir for 4-6 hours, and the reaction is completed to obtain an addition product; A sodium hydroxide aqueous solution with a mass fraction of 10-20% is added to the addition product at a volume ratio of 1:3-4; a saponification reaction is carried out at a temperature of 80-90° C., stirring is continued for 2-3 hours, cooling to room temperature, and then solid-liquid separation and drying are carried out to obtain branched sodium oleate.

7. A green disposal method for phosphogypsum as claimed in claim 4, characterized in that: The method for preparing a long-chain quaternary ammonium salt by quaternizing a long-chain fatty amine with dimethyl sulfate is as follows: dodecylamine and dimethyl sulfate are taken in a ratio of 50g:30g; dodecylamine is then heated from room temperature to 50-55°C under stirring; dimethyl sulfate is then added dropwise, and the dropping speed is controlled to keep the reaction temperature at 50-60°C; after the dropping is completed, the reaction is stirred at a constant temperature for 3-5h, and the reaction is completed to obtain a long-chain quaternary ammonium salt.

8. A green disposal method for phosphogypsum as claimed in claim 4, characterized in that: The styrene anion exchange resin contains quaternary ammonium salt.

9. A green disposal method for phosphogypsum as claimed in claim 8, characterized in that: The preparation method of the styrene anion exchange resin is: S3-1, taking water, gelatin and sodium phosphate in a mass ratio of 100-120:1:2-3, mixing, and stirring at 45-55°C for 1-2h to obtain an aqueous phase; S3-2, taking styrene, divinylbenzene, benzoyl peroxide and a porogen in a mass ratio of 15-20:10:0.1:25-30 and mixing them evenly to obtain an oil phase; S3-3, taking the water phase and the oil phase in a mass ratio of 2 to 3:1, first stirring the water phase and heating it to 60 to 65°C, then adding the oil phase, continuing to heat it to 80 to 85°C, stirring for 15 to 20 minutes, then heating it to 90 to 94°C and stirring for 8 to 10 minutes, cooling it to 85 to 87°C and stirring for 4 to 6 minutes, then heating it to 95 to 99°C and stirring for 15 to 20 minutes, to obtain a pretreated polymer; S3-4. Take the pretreated polymer, ethylene dichloride and N,N-dimethylhexadecylamine in a mass ratio of 10 to 13:50 to 55:2, mix them, and stir them at a temperature of 95 to 99° C. for 8 to 11 hours to obtain a styrene anion exchange resin.

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