A green disposal method of phosphogypsum

Abstract

The application discloses a green disposal method of phosphogypsum, comprising the following steps: S1, phosphogypsum pretreatment; S2, micro-bubble flotation; and S3, removal of impurity ions. The method can utilize a collector to perform surface modification on the micro-bubbles, and then modified bubbles with a targeted adsorption function are obtained, so that the micro-bubbles are easy to selectively adhere to impurities, and the impurity removal effect on the phosphogypsum mixed solution is enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of environmental protection, in particular to a green disposal method of phosphogypsum. BACKGROUND

[0002] Phosphogypsum is a by-product generated in the production process of phosphoric acid, and its main source is calcium sulfate precipitate generated in the reaction of phosphorite and sulfuric acid to prepare phosphoric acid. After filtration and washing, the precipitate forms phosphogypsum, which usually contains a certain amount of moisture, unreacted phosphorite, fluorides, heavy metals and radioactive elements and other impurities.

[0003] At present, the large amount of phosphogypsum produced has led to its long-term accumulation, which has become a major source of environmental problems. Long-term accumulation of phosphogypsum can cause a series of environmental safety problems. Compared with general gypsum, phosphogypsum contains more impurities, such as phosphoric acid and its salt impurities, fluoride impurities, organic matter impurities, SiO2, and part of heavy metal ions, radioactive elements, etc. The water resistance of phosphogypsum is poor, and the whiteness and hardness are not as good as gypsum in many aspects, which greatly limits its application field and makes it difficult to achieve resource utilization. In view of this hot issue, domestic and foreign enterprises have carried out long-term research, but this world problem has not been solved. In particular, China's phosphorus chemical industry is currently facing the problems of large storage of phosphogypsum, which is still growing rapidly, and low added value of products after phosphogypsum processing. In addition, the existing phosphogypsum technology is high in cost and heavy in pollution, for example, the water washing method consumes a large amount of water resources, and the wastewater after washing is still difficult to handle; the pyrogenic method faces the problems of high risk and high energy consumption. Therefore, a green disposal process needs to be developed to realize the resource utilization of phosphogypsum while not 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. Lime neutralization method and water washing method are effective methods for removing water-soluble phosphorus and water-soluble fluorine in phosphogypsum, and lime neutralization method has the characteristics of simple process and small investment cost, and is widely used in practice. Water washing method is simple to operate and has significant impurity removal effect, but it has high investment cost, large amount of washing water and high energy consumption, and generally has economic competitiveness when the phosphogypsum treatment scale exceeds 100,000 tons per year. Flotation method is suitable for treating phosphogypsum with high quartz content, and the treated high-quality phosphogypsum can be used to prepare downstream high-value products. Through the investigation of the current situation of China's phosphogypsum in the past two years, it is understood that the main utilization way of phosphogypsum produced by enterprises at present is to prepare cement retarder and building gypsum powder and other building material products, which have low product value and small sales radius. Therefore, the pretreatment method generally adopted by enterprises is the low-cost lime stacking treatment process, but it has the problems of large occupied area, long stacking reaction time and pollution of the surrounding environment. SUMMARY

[0005] In order to solve the above problems, the present application provides a green disposal method of phosphogypsum.

[0006] A green disposal method of phosphogypsum, comprising the following steps:

[0007] S1, pretreatment of phosphogypsum;

[0008] The phosphogypsum is crushed and ground, and then passed through a 200-mesh screen to obtain phosphogypsum powder. The phosphogypsum powder is mixed with water to form a slurry with a mass concentration of 20-40%. The pH value of the slurry is adjusted to 5-8.

[0009] S2, micro-bubble flotation;

[0010] A collector is added to a micro-bubble generator, which then produces modified micro-bubbles modified by the collector. The slurry and the modified micro-bubbles are then stirred in a flotation tank, and then floated to form a foam layer composed of micro-bubbles and impurities, a phosphogypsum layer after impurity removal, and a liquid layer after impurity removal. The foam layer composed of micro-bubbles and impurities and the phosphogypsum layer after impurity removal are recovered, and the liquid layer after impurity removal is processed further.

[0011] The collector is added in an amount of 1-2 g per liter of working liquid in the micro-bubble generator. The stirring speed is 1200-1500 rpm, the stirring time is 20-25 min, the gas flow rate of the micro-bubble generator is 0.4-0.6 m 3 / min, and the diameter of the modified micro-bubbles is 1-50 μm.

[0012] S3, removal of impurity ions;

[0013] The liquid layer after impurity removal is passed through an exchange column of styrene anion exchange resin for adsorption treatment for 1-2 h, which completes the treatment. The liquid layer after impurity removal is passed through the exchange column at a speed of 5-10 BV / h.

[0014] By the above method, the micro-bubbles can be surface-modified by the collector to obtain modified bubbles with targeted adsorption function, so that the micro-bubbles are easily adhered to the impurities (such as siliceous substances), thereby enhancing the impurity removal effect of the phosphogypsum mixture. Specifically, the effective groups such as COOH branches in the collector can change the surface physical and chemical properties of the bubbles and the siliceous impurities at the same time during adsorption.

[0015] Further, the collector is sodium oleate.

[0016] Description: Sodium oleate as an ion collector has high collection efficiency and selectivity. In the phosphogypsum mixed solution, sodium oleate can adsorb specific impurity ions, thereby realizing effective separation of impurities and phosphogypsum. This selective separation capability helps reduce the loss of useful components and improve the purity of phosphogypsum.

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

[0018] Description: Using water as the working liquid in the microbubble generator will not pollute the environment, and mixing with a surfactant can adjust the generation and properties of bubbles to meet different application requirements.

[0019] Further, the collector is modified sodium oleate, and the preparation method of the modified sodium oleate comprises:

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

[0021] S2-2, quaternary ammonium reaction of long carbon chain fatty amine and dimethyl sulfate to prepare a long carbon chain quaternary ammonium salt;

[0022] S2-3, mixing and stirring the branched sodium oleate and the long carbon chain quaternary ammonium salt according to a mass ratio of 1-2:1 to obtain modified sodium oleate.

[0023] Description: The microbubbles attached with sodium oleate are used for flotation of the phosphogypsum mixed solution by the above method, which can improve the flotation efficiency compared with directly adding sodium oleate or using microbubbles alone. Sodium oleate as a collector can selectively adsorb specific impurities in the phosphogypsum mixed solution, and microbubbles as carriers can carry these impurities collected by sodium oleate to float to the liquid surface. The modified microbubbles are more likely to selectively adhere to impurities, thereby realizing separation. The long carbon chain quaternary ammonium salt has strong surface activity and can form a firm adsorption layer on the surface of the mineral, and has a synergistic effect with the modified microbubbles. This synergistic effect makes the flotation process more efficient, improves the collection efficiency, and can significantly improve the removal rate of impurities.

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

[0025] Description: The above COOH belongs to a hydrophilic group, which helps to form a bond with the mineral, thereby strengthening the targeted adsorption on the surface of the target mineral and improving the collection effect.

[0026] Further, the method for introducing a branched chain on the carbon chain of the sodium oleate to obtain branched sodium oleate comprises:

[0027] The oleic acid and maleic anhydride are weighed in a ratio of 7:1, and then a catalyst accounting for 0.2-0.8 wt% of the maleic anhydride is added. Under nitrogen protection, the temperature is slowly raised to 60-70℃, and constant temperature and stirring are continued for 4-6 h. After the reaction is completed, the addition product is obtained.

[0028] The addition product is added with a 10-20 wt% sodium hydroxide aqueous solution in a volume ratio of 1:3-4. Saponification is carried out at a temperature of 80-90℃, and constant stirring is continued for 2-3 h. After cooling to room temperature, solid-liquid separation and drying are carried out to obtain branched sodium oleate.

[0029] Description: The sodium oleate obtained above has a hydrophilic sodium carboxylate group at one end of the molecule and a hydrophobic long carbon chain at the other end. This unique "amphiphilic" structure enables the micro-bubbles to have a targeted adsorption function.

[0030] Further, the method for preparing the long carbon chain quaternary ammonium salt by quaternary ammonium reaction of the long carbon chain fatty amine and dimethyl sulfate is as follows: dodecylamine and dimethyl sulfate are taken in a ratio of 50g:30g. The dodecylamine is heated to 50-55℃ under stirring from room temperature, and then the dimethyl sulfate is added dropwise, with the dropping speed controlled so that the reaction temperature is 50-60℃. After the addition is completed, constant temperature stirring is continued for 3-5 h. The long carbon chain quaternary ammonium salt is obtained after the reaction is completed.

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

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

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

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

[0035] S3-1. Water, gelatin and sodium phosphate are taken in a mass ratio of 100-120:1:2-3 and mixed, and stirring is continued at 45-55℃ for 1-2 h to obtain an aqueous phase.

[0036] S3-2. Styrene, divinylbenzene, benzoyl peroxide and a pore former are taken in a mass ratio of 15-20:10:0.1:25-30 and uniformly mixed to obtain an oil phase.

[0037] S3-3, taking the water phase and the oil phase in a mass ratio of 2-3:1, first stirring the water phase and heating to 60-65 DEG C, then adding the oil phase, continuing to heat to 80-85 DEG C, then stirring for 15-20 min, then heating to 90-94 DEG C, stirring for 8-10 min, cooling to 85-87 DEG C, stirring for 4-6 min, then heating to 95-99 DEG C, stirring for 15-20 min, to obtain a pretreated polymer;

[0038] S3-4, according to the mass ratio of 10-13:50-55:2, taking the pretreated polymer, dichloroethane and N,N-dimethylhexadecylamine, then mixing and stirring at a temperature of 95-99 DEG C for 8-11 h to obtain a styrene anion exchange resin.

[0039] Description: The above method introduces a quaternary ammonium salt group into the styrene anion exchange resin, which can significantly improve the ion exchange capacity and selectivity of the resin. The high ion exchange capacity enables the resin to quickly and accurately capture and remove harmful ions such as nitrate, sulfate 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 application are:

[0041] The present application can use a collector to modify the surface of micro-bubbles to obtain modified bubbles with targeted adsorption function, so that the micro-bubbles are easy to selectively adhere to impurities (such as siliceous substances), thereby strengthening the effect of removing impurities from phosphogypsum mixed liquid. Specifically, by increasing effective groups such as COOH branches in the collector, the surface physical and chemical properties of the bubbles and siliceous impurities can be changed at the same time during adsorption. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a schematic diagram of the modified micro-bubble flotation principle in the embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to further illustrate the manner in which the present application is carried out and the effects achieved, the technical solutions of the present application will be described below in conjunction with experiments.

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

[0045] S1, phosphogypsum pretreatment;

[0046] The phosphogypsum is crushed and ground, then passed through a 200-mesh screen to obtain phosphogypsum powder, the phosphogypsum powder is mixed with water to form a slurry with a mass concentration of 30%, and the pH value of the slurry is adjusted to 7.

[0047] S2, micro-bubble flotation;

[0048] Adding a collector in a micro-bubble generator, then the micro-bubble generator produces modified micro-bubbles modified by the collector, then stirring the slurry with the modified micro-bubbles in a flotation tank, then flotation, forming a foam layer of micro-bubbles and impurities, a phosphogypsum layer after impurity removal and a liquid layer after impurity removal, recovering the foam layer of micro-bubbles and impurities, the phosphogypsum layer after impurity removal and the liquid layer after impurity removal for further processing;

[0049] The collector is added in an amount of 1.5 g per liter of working liquid in the micro-bubble generator; the stirring speed is 1300 rpm, the stirring time is 23 min, the gas flow of the micro-bubble generator is 0.5 m 3 / min, and the diameter of the modified micro-bubbles is 10 μm;

[0050] The collector is sodium oleate; the working liquid of the micro-bubble generator is water;

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

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

[0053] S2-2, quaternary ammonium salt of long carbon chain is prepared by quaternary ammonium reaction of long carbon chain fatty amine and dimethyl sulfate;

[0054] S2-3, the branched sodium oleate and the long carbon chain quaternary ammonium salt are mixed and stirred according to 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 the sodium oleate to obtain branched sodium oleate is:

[0056] The molar ratio of oleic acid to maleic anhydride is 7:1, and the catalyst accounts for 0.5wt% of maleic anhydride; under nitrogen protection, slowly warm up to 65℃, constant temperature and continuous stirring reaction for 5h, reaction is completed, addition product is obtained;

[0057] The volume ratio of the addition product to the sodium hydroxide aqueous solution is 1:3.5, and the mass fraction of the sodium hydroxide aqueous solution is 15%; at a temperature of 85℃, saponification reaction is carried out, and stirring is continued for 2.5h, then cooled to room temperature, then solid-liquid separation and drying to obtain branched sodium oleate;

[0058] The method for preparing the long carbon chain quaternary ammonium salt by subjecting the long carbon chain fatty amine to a quaternary ammonium reaction with dimethyl sulfate is as follows: taking dodecylamine and dimethyl sulfate in a ratio of 50g:30g; then heating the dodecylamine under stirring from room temperature to 52℃, and then adding the dimethyl sulfate dropwise, controlling the dropwise adding speed so that the reaction temperature is at 55℃; after the dropwise adding is completed, constant temperature stirring reaction is carried out for 4h, and the reaction is completed to obtain the long carbon chain quaternary ammonium salt;

[0059] S3, removing impurity ions;

[0060] The impurity-removed liquid layer is passed into an exchange column of styrene anion exchange resin for adsorption treatment, and the adsorption treatment time is 1.5h, that is, the treatment is completed, wherein the passing speed of the impurity-removed liquid layer is 7BV / 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, taking water, gelatin and sodium phosphate in a mass ratio of 110:1:2.5, and mixing, and stirring at 50℃ for 1.5h to obtain an aqueous phase;

[0063] S3-2, taking styrene, divinylbenzene, benzoyl peroxide and pore former in a mass ratio of 18:10:0.1:28, and mixing uniformly to obtain an oil phase;

[0064] S3-3, taking the aqueous phase and the oil phase in a mass ratio of 2.5:1, first stirring the aqueous phase and heating to 63℃, then adding the oil phase, continuing to heat to 83℃, and then stirring for 18min, then heating to 90-94℃, stirring for 8-10min, cooling to 86℃, stirring for 5min, then heating to 97℃, and stirring for 18min to obtain a pretreated polymer;

[0065] S3-4, taking the pretreated polymer, dichloroethane and N,N-dimethylhexadecylamine in a mass ratio of 12:52:2, then mixing, and stirring and reacting at a temperature of 95-99℃ for 9h to obtain the styrene anion exchange resin.

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

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

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

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

[0070] Example 6: The difference between this example and Example 1 is that the processing parameters in S3 are different, the impurity-removed liquid layer is passed into the exchange column of styrene anion exchange resin for adsorption treatment, and the adsorption treatment time is 1h, that is, the treatment is completed, wherein the passing speed of the impurity-removed liquid layer is 10BV / h.

[0071] Example 7: The difference between this example and Example 1 is that the processing parameters in S3 are different, the impurity-removed liquid layer is passed into the exchange column of styrene anion exchange resin for adsorption treatment, and the adsorption treatment time is 2h, that is, the treatment is completed, wherein the passing speed of the impurity-removed liquid layer is 5BV / h.

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

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

[0074] Example 10: The difference between this example and Example 1 is that the preparation parameters of the branched sodium oleate are different, and the method is: oleic acid and maleic anhydride are weighed according to a molar ratio of 7:1, then a catalyst accounting for 0.2wt% of maleic anhydride is added, the temperature is slowly raised to 60℃ under nitrogen protection, and the reaction is continuously stirred at constant temperature for 6h, and the addition product is obtained after the reaction is completed;

[0075] The branched sodium oleate is obtained by adding 20wt% sodium hydroxide aqueous solution to the addition product in a volume ratio of 1:3, performing saponification reaction at 80℃, continuously stirring for 2h, cooling to room temperature, and then performing solid-liquid separation and drying.

[0076] In example 11, the branched sodium oleate is prepared by using different parameters, that is, taking oleic acid and maleic anhydride in a molar ratio of 7:1, adding 0.8wt% catalyst based on the maleic anhydride, slowly heating to 70℃ under nitrogen protection, and continuously stirring for 4h at constant temperature to obtain the addition product.

[0077] The branched sodium oleate is obtained by adding 10wt% sodium hydroxide aqueous solution to the addition product in a volume ratio of 1:4, performing saponification reaction at 90℃, continuously stirring for 3h, cooling to room temperature, and then performing solid-liquid separation and drying.

[0078] In example 12, the long-chain quaternary ammonium salt is prepared by using different parameters, that is, taking dodecylamine and dimethyl sulfate in a ratio of 50g:30g, heating dodecylamine to 55℃ under stirring, then adding dimethyl sulfate dropwise, controlling the dropping speed to make the reaction temperature at 60℃, and continuously stirring for 3h at constant temperature after the addition is completed to obtain the long-chain quaternary ammonium salt.

[0079] In example 13, the long-chain quaternary ammonium salt is prepared by using different parameters, that is, taking dodecylamine and dimethyl sulfate in a ratio of 50g:30g, heating dodecylamine to 50℃ under stirring, then adding dimethyl sulfate dropwise, controlling the dropping speed to make the reaction temperature at 50℃, and continuously stirring for 5h at constant temperature after the addition is completed to obtain the long-chain quaternary ammonium salt.

[0080] In example 14, the styrene anion exchange resin is prepared by using different parameters, that is, S3-1, taking water, gelatin and sodium phosphate in a mass ratio of 100:1:3, and mixing to obtain an aqueous phase under stirring at 45℃ for 1h;

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

[0082] S3-3, taking the water phase and the oil phase with a mass ratio of 2:1, first stirring the water phase and heating to 60℃, then adding the oil phase, continuing to heat to 85℃, then stirring for 20 min, then heating to 90℃ and stirring for 8 min, cooling to 85℃ and stirring for 4 min, then heating to 95℃ and stirring for 15 min, to obtain a pretreated polymer;

[0083] S3-4, taking the pretreated polymer, dichloroethane and N,N-dimethylhexadecylamine with a mass ratio of 10:50:2, then mixing and stirring at a temperature of 95℃ for 8h to obtain a styrene anion exchange resin.

[0084] Example 15: The difference between this example and Example 1 is that the preparation parameters of the styrene anion exchange resin are different, and the method is as follows: S3-1, taking water, gelatin and sodium phosphate with a mass ratio of 120:1:2, mixing and stirring at 55℃ for 2h to obtain a water phase;

[0085] S3-2, taking styrene, divinylbenzene, benzoyl peroxide and a pore former with a mass ratio of 20:10:0.1:30, mixing uniformly to obtain an oil phase;

[0086] S3-3, taking the water phase and the oil phase with a mass ratio of 3:1, first stirring the water phase and heating to 65℃, then adding the oil phase, continuing to heat to 80℃, then stirring for 15 min, then heating to 94℃ and stirring for 10 min, cooling to 87℃ and stirring for 6 min, then heating to 99℃ and stirring for 20 min to obtain a pretreated polymer;

[0087] S3-4, taking the pretreated polymer, dichloroethane and N,N-dimethylhexadecylamine with a mass ratio of 13:55:2, then mixing and stirring at a temperature of 99℃ for 11h to obtain a styrene anion exchange resin.

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

[0089] Experimental example: The description of this experimental example is based on the description of Example 1, and is intended to illustrate the actual application effect of the present application.

[0090] I. The phosphogypsum is treated by the method of Example 1 to Example 16 and Comparative Example 1 to Comparative Example 5, to obtain the removal rate of silicon impurities in the phosphogypsum, and the fluorine in the phosphogypsum before treatment is in an over-standard state with reference to the index in GB / T 23456-2018 “Phosphogypsum”; before S3 adsorption treatment, the fluorine content in the liquid layer after impurity removal is 4-5 mg / L (more than 1.0 mg / L, 1.0 mg / L is the fluorine ion concentration harmful to the human body); after the adsorption treatment is completed, it is found through experiments that the fluorine content in the phosphogypsum treated by the examples of the application does not exceed the standard, but the fluorine content in Comparative Example 1 and Comparative Example 2 exceeds the standard, which may be because the method in Comparative Example 1 and Comparative Example 2 is not completely treated by flotation, and the fluorine in the phosphogypsum is not completely released into the liquid layer;

[0091] The results obtained are as follows:

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

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

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

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

[0096] Comparative Example 4: The difference from Example 1 is that sodium oleate is not used in combination with long-chain quaternary ammonium salt, but only sodium oleate is used as a collector.

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

[0098] Example 1, Comparative Examples 1-5 are compared, as shown in Table 1,

[0099] Table 1: Impurity removal experiment results of phosphogypsum treated by different methods

[0100]

[0101] From Table 1, it can be seen that by comparing Example 1 with Comparative Example 1, it can be seen that, Figure 1As shown, the flotation by using the modified microbubbles in Example 1 makes the microbubbles have the function of targeted adsorption, plays the conjugate induction effect of the collector, and improves the removal rate of the impurities in the phosphogypsum mixed solution; in contrast, in Comparative Example 1, only the flotation function of the microbubbles is used for the adsorption of the impurities, and it is impossible to realize the efficient and targeted removal of the impurities in the mixed solution, and therefore, the method of using the modified microbubbles in Example 1 is more preferred;

[0102] As can be seen from the comparison between Comparative Example 1 and Comparative Example 2, compared with the method of directly adding the collector into the phosphogypsum mixed solution in Comparative Example 2, the impurity removal effect of attaching the collector on the microbubbles in Example 1 is more preferred, which may be because, in Example 1, the collector is attached on the surface of the microbubbles, which can enhance the contact area and the attachment strength between the microbubbles and the impurity objects, and thus improve the impurity removal effect, while in Comparative Example 2, the collector is directly added into the mixed solution, which may cause the complexation between the collector and the impurity objects, and the flotation of the microbubbles on the complex, so that the direct adsorption effect of the microbubbles is reduced, resulting in a lower removal rate than that of Example 1.

[0103] As can be seen from the comparison between Comparative Example 1 and Comparative Example 3, the removal effect of the impurities after the microbubbles are modified by using the commercially available sodium oleate as the collector and then floated in Comparative Example 3 is not as good as that of Example 1, which may be because, in the prior art of Comparative Example 3, the sodium oleate is not improved, and the hydrophilic group of the sodium oleate is not rich enough, and in Example 1, the branched chain is added, so that the collector has a better collection effect on the impurities, and thus the removal rate of the impurities is improved.

[0104] As can be seen from the comparison between Comparative Example 1 and Comparative Example 4, in Example 1, the sodium oleate with the branched chain is mixed with the long-chain quaternary ammonium salt and used, which can further improve the collection effect, and the reason is that the mixture of the sodium oleate and the long-chain quaternary ammonium salt can form a synergistic effect, and together improve the removal effect of the impurities in the phosphogypsum mixed solution.

[0105] As can be seen from the comparison between Comparative Example 1 and Comparative Example 5, the styrene anion exchange resin prepared by using the method of the present application in Example 1 has a good treatment effect on the impurities, and effectively adsorbs the pollution ions in the liquid, while in Comparative Example 5, the styrene anion exchange resin in the prior art is directly used, and the fluorine ion treatment effect needs to be improved, which may be because, the preparation method in Example 1 can form a resin with a more optimal structure and a better adsorption effect.

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

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

[0108] Table 2 impurity removal effect 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 Comparative Example 1, Example 4 and Example 5, it can be found that the microbubble treatment parameters of Example 1 are more preferred, which may be because the parameters of Example 1 are more suitable for the environment of the phosphogypsum mixed solution; by comparing Comparative Example 1, Example 6 and Example 7, it can be found that the adsorption treatment parameters of Example 1 are more preferred; by comparing Comparative 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 preferred, which may be because under this ratio, sodium oleate and long-chain quaternary ammonium salt can better play a synergistic effect and improve the impurity removal rate; by comparing Comparative Example 1, Example 10 and Example 11, it can be found that the preparation parameters of branched sodium oleate in Example 1 are more preferred; by comparing Comparative 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 preferred; by comparing Comparative 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 preferred.

Claims

1. A green disposal method of phosphogypsum, characterized by, The method comprises the following steps: S1, phosphogypsum pretreatment; The phosphogypsum is crushed and ground, and then passed through a 200-mesh screen to obtain phosphogypsum powder, the phosphogypsum powder is mixed with water to form a slurry with a mass concentration of 20-40%, and the pH value of the slurry is adjusted to 5-8; S2, micro-bubble flotation; A collector is added to a micro-bubble generator, the micro-bubble generator then generates modified micro-bubbles modified by the collector, the slurry is then stirred with the modified micro-bubbles in a flotation tank, and then flotation is performed to form a foam layer composed of micro-bubbles and impurities, a phosphogypsum layer after impurity removal, and a liquid layer after impurity removal, the foam layer composed of micro-bubbles and impurities and the phosphogypsum layer after impurity removal are recovered, and the liquid layer after impurity removal is subjected to the next treatment; The collector is added in an amount of 1-2 g per liter of working liquid of the micro-bubble generator, the stirring speed is 1200-1500 rpm, the stirring time is 20-25 min, the air flow of the micro-bubble generator is 0.4-0.6 m 3 / min, and the diameter of the modified micro-bubbles is 1-50 μm.

2. The method according to claim 1, wherein the collector is added in an amount of 1-2 g per liter of working liquid of the micro-bubble generator, the stirring speed is 1200-1500 rpm, the stirring time is 20-25 min, the air flow of the micro-bubble generator is 0.4-0.6 m 3 / min, and the diameter of the modified micro-bubbles is 1-50 μm. S3, removal of impurity ions; 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 1-2 h, and the treatment is completed, wherein the passing speed of the liquid layer after impurity removal is 5-10 BV / h; The preparation method of the styrene anion exchange resin is as follows: S3-1, water, gelatin and sodium phosphate are taken in a mass ratio of 100-120:1:2-3 and mixed, and stirring is performed at 45-55 DEG C for 1-2 h to obtain an aqueous phase; S3-2, styrene, divinylbenzene, benzoyl peroxide and a pore former are taken in a mass ratio of 15-20:10:0.1:25-30 and uniformly mixed to obtain an oil phase; S3-3, the aqueous phase and the oil phase are taken in a mass ratio of 2-3:1, the aqueous phase is first stirred and heated to 60-65 DEG C, then the oil phase is added, the temperature is continuously increased to 80-85 DEG C, and then stirring is performed for 15-20 min, then the temperature is increased to 90-94 DEG C and stirring is performed for 8-10 min, the temperature is decreased to 85-87 DEG C and stirring is performed for 4-6 min, then the temperature is increased to 95-99 DEG C and stirring is performed for 15-20 min, and a pretreated polymer is obtained; S3-4, the pretreated polymer, dichloroethane and N,N-dimethylhexadecylamine are taken in a mass ratio of 10-13:50-55:2, then mixed, and stirred and reacted at a temperature of 95-99 DEG C for 8-11 h to obtain a styrene anion exchange resin.

2. A method for green disposal of phosphogypsum as claimed in claim 1 wherein, The collector is sodium oleate.

3. A method for green disposal of phosphogypsum as claimed in claim 1 wherein, The working liquid of the micro-bubble generator is water or a surfactant.

4. A method for green disposal of phosphogypsum as claimed in claim 1 wherein, The collector is modified sodium oleate, and the preparation method of the modified sodium oleate comprises: S2-1, introducing a branch chain on the carbon chain of the sodium oleate to obtain branched sodium oleate; S2-2, quaternary ammonium salt of long carbon chain is prepared by quaternary ammonium reaction of long carbon chain fatty amine and dimethyl sulfate; S2-3, the branched sodium oleate and the long carbon chain quaternary ammonium salt are mixed and stirred in a mass ratio of 1-2:1 to obtain modified sodium oleate.

5. A method for green disposal of phosphogypsum as claimed in claim 4 wherein, The branch chain in S2-1 is COOH.

6. A method for green disposal of phosphogypsum as claimed in claim 5 wherein, The method for introducing a branch chain on the carbon chain of the sodium oleate to obtain branched sodium oleate is as follows: The oleic acid and maleic anhydride are weighed in a ratio of 7:1, then a catalyst accounting for 0.2-0.8 wt% of the maleic anhydride is added, under nitrogen protection, the temperature is slowly raised to 60-70℃, constant temperature and continuous stirring reaction for 4-6h, the reaction is completed, and the addition product is obtained; The addition product is added with a sodium hydroxide aqueous solution with a mass fraction of 10-20% in a volume ratio of 1:3-4, a saponification reaction is carried out at a temperature of 80-90℃, continuous stirring for 2-3h, cooling to room temperature, then solid-liquid separation and drying to obtain branched sodium oleate.

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

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

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