Agent for phosphogypsum decrement conversion and use method thereof

Abstract

The invention discloses a medicament for phosphogypsum decrement conversion and a use method thereof, the medicament is composed of ammonium carbonate, chitosan and epichlorohydrin, the chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surfaces of the microspheres are provided with negatively charged cation exchange membranes. Through the synergistic effect of inorganic salt ammonium carbonate and organic matter chitosan, phosphogypsum is efficiently treated, and reduction conversion of phosphogypsum and recovery of calcium and sulfur elements are achieved. Under normal temperature and normal pressure, the process can effectively promote conversion of a calcium system, and small-particle solids and a solution rich in nutrient elements are obtained. According to the invention, the stockpiling amount of solid wastes is obviously reduced, and a wider application way is developed for a large amount of calcium and sulfur elements in phosphogypsum.

Description

Technical Field

[0001] The present invention relates to the field of resource and environmental technology, and in particular to an agent for reducing and converting phosphogypsum and a method for using the agent. Background Art

[0002] Phosphogypsum is a solid waste discharged during the production of phosphate fertilizers by the phosphoric acid industry. It is a byproduct of the ammonium phosphate industry and is mainly composed of calcium sulfate. About 150 million tons of phosphogypsum are discharged worldwide each year. It is difficult to recycle as a resource due to its harmful components. The total stockpile volume has exceeded 6 billion tons. Phosphogypsum contains impurities such as fluoride, free phosphoric acid, phosphate, P2O5, etc., which will cause air, water and soil pollution during the stacking process. However, its overall utilization rate is low. The global comprehensive utilization rate of phosphogypsum is only about 10%. The harmless treatment of phosphogypsum and the development of large-scale application solutions are currently urgently needed. At present, in addition to its application in the fields of building materials and chemical industry, phosphogypsum has also been expanded to agriculture. From the perspective of elemental composition, phosphogypsum contains a large amount of sulfur and calcium, which are essential medium-nutrient elements for plants. The rational application of sulfur and calcium fertilizers can increase crop yields, improve product quality and improve soil. However, what plants can absorb and utilize is effective calcium, not calcium sulfate in phosphogypsum. Therefore, it is of great significance to develop new agents or technologies to promote the conversion of calcium in phosphogypsum and use it to prepare medium-element fertilizers in the treatment and application of phosphogypsum. Summary of the invention

[0003] Technical problem to be solved: The technical problem to be solved by the present invention is to provide an agent for the reduction and transformation of phosphogypsum, which is used to promote the reduction and calcium transformation of phosphogypsum and obtain a fertilizer at the same time.

[0004] Technical solution: An agent for reducing the amount of phosphogypsum, composed of ammonium carbonate, chitosan and epichlorohydrin. Chitosan and epichlorohydrin are cross-linked to form porous microspheres. Ammonium carbonate is loaded in the microspheres, and a negatively charged cation exchange membrane is provided on the surface of the microspheres. Preferably, the preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. epichlorohydrin and a base were added to the ammonium carbonate-chitosan emulsion, heated and stirred for reaction, filtered, washed and freeze-dried to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride to carry out a polymerization reaction, taken out, dried and washed to obtain a drug. Preferably, in step S11, the mass ratio of chitosan to epichlorohydrin is 1:0.5-0.7, and the heating temperature is 50-70°C. Preferably, in step S13, the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1-2:1-2:1. Preferably, the method for using the agent comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum to water, add the reagent in proportion, introduce ammonia, and stir at room temperature and pressure until the reaction is complete; S3. The liquid after the reaction is subjected to solid-liquid centrifugal separation to obtain a solution rich in nutrient elements and solid particles. Preferably, in step S2, the solid-liquid ratio of phosphogypsum to water is 1:2-4, the molar ratio of ammonia, phosphogypsum and ammonium carbonate in the reagent is 0.5-0.9:1:1-1.2, and the stirring time is 45-50 hours. Preferably, the centrifugal separation speed in step S3 is 500-800 r / min. Beneficial effects: The present invention has the following characteristics: The agent of the present invention is composed of a composite of inorganic and organic substances, and has a negatively charged cation exchange membrane on the surface. Under the synergistic effect of organic and inorganic substances, it can efficiently adsorb and precipitate calcium ions in phosphogypsum, obtain a solution rich in sulfate, and facilitate solid-liquid separation. The main component of phosphogypsum is calcium sulfate, and making full use of the calcium sulfate therein is the key to the resource utilization of phosphogypsum. According to the calculation of the reaction equilibrium constant, the reaction of calcium sulfate and ammonium carbonate can generate a large trend of ammonium sulfate and calcium carbonate precipitation. It is theoretically feasible to select ammonium carbonate as a conversion agent to promote the conversion of phosphogypsum, and after the ammonium ions are replaced by calcium ions, the ammonium sulfate in the solution can be used as a fertilizer. However, there are metal ion impurities such as iron ions, copper ions, and magnesium ions in phosphogypsum, which will affect the conversion rate of calcium and sulfur, and iron ions will react with carbonate to precipitate, which is easy to affect the purity of calcium carbonate. In order to improve the selectivity of the conversion agent, it is necessary to prepare a suitable carrier to reduce the generation of side reactions. Chitosan is a natural polysaccharide with abundant hydroxyl and amino groups on its molecular chain. It is easy to chemically modify and is a good carrier. Chitosan is used as raw material and epichlorohydrin is used as a cross-linking agent. Porous microspheres can be prepared by freeze drying. They can be used as carriers of ammonium nitrate. At the same time, the abundant hydroxyl and amino functional groups on chitosan can also react with metal ions to remove impurity metal ions and effectively improve the selectivity of the conversion agent. In addition to metal ions, there are also anions such as phosphate and fluoride in phosphogypsum. Among them, phosphate will also precipitate with calcium ions, affecting the conversion rate of calcium ions, and chitosan porous microspheres cannot filter these anions. In order to reduce the content of anions, a cation exchange membrane is prepared on the surface of chitosan porous microspheres through interfacial polymerization, and sulfonate is added to the reactants of the polymerization reaction to make the membrane negatively charged, thereby repelling anions and selectively passing cations, so that the purity of the generated reactants is further improved. Compared with the prior art, the present invention has the following advantages and positive effects: The present invention reduces the stockpile volume of solid waste and the risk of secondary pollution, converts useful elements in solid waste into usable resources, and has significant environmental and economic benefits. The present invention is carried out at normal temperature and pressure, thus avoiding the energy consumption and equipment costs caused by traditional high temperature and high pressure treatment. The implementation process of the present invention is simple and easy to operate, the solid-liquid ratio and liquid concentration range are flexible, the conversion time is short, the treatment effect is good, and the scheme adaptability is strong. DETAILED DESCRIPTION In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. Specific preferred examples are as follows: Embodiment 1: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.5, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate were immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, the water was removed and dried, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization, and then removed, dried and washed to obtain a pharmaceutical agent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:2, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 2: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:1:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:2, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 3: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.7, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:1:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:2, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 4: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1.5:1.5:1, taken out, dried and washed to obtain a drug; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:2, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 5: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 2:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:2, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 6: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:1.5:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:2, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 7: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:2, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 8: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:3, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 9: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S3. The liquid after the reaction is subjected to solid-liquid centrifugal separation at a rotation speed of 600 r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 10: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:3, add reagents according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.7:1:1.1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Embodiment 11: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:3, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.7:1:1.2, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. In order to further illustrate the technical effect of the present invention, the present invention also provides a comparative example, which is as follows: Comparative Example 1: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.4, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:1:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:2, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Comparative Example 2: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 0.5:0.5:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:2, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Comparative Example 3: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:1, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.5:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Comparative Example 4: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:3, add the reagent according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.3:1:1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Comparative Example 5: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein chitosan and epichlorohydrin are cross-linked to form porous microspheres, the microspheres are loaded with ammonium carbonate, and the surface of the microspheres has a negatively charged cation exchange membrane; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:3, add reagents according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.9:1:1.4, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Comparative Example 6: A reagent for reducing and converting phosphogypsum, comprising ammonium carbonate, chitosan and epichlorohydrin, wherein the chitosan and epichlorohydrin are cross-linked to form porous microspheres, and the ammonium carbonate is loaded in the microspheres; The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the ammonium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with ammonium carbonate; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:3, add reagents according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and ammonium carbonate in the reagent of 0.7:1:1.1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. Comparative Example 7: A reagent for reducing and converting phosphogypsum, which is composed of sodium carbonate, chitosan and epichlorohydrin. Chitosan and epichlorohydrin are cross-linked to form porous microspheres, in which sodium carbonate is loaded, and a negatively charged cation exchange membrane is provided on the surface of the microspheres. The preparation method of the medicament comprises the following steps: S11. Sodium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain a sodium carbonate - chitosan emulsion; S12. Add epichlorohydrin and alkali to the sodium carbonate-chitosan emulsion, heat and stir to react at 60°C, the mass ratio of chitosan to epichlorohydrin is 1:0.6, filter, wash and freeze-dry to obtain porous microspheres loaded with sodium carbonate; S13. The porous microspheres loaded with sodium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride for polymerization reaction, wherein the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1:2:1, taken out, dried and washed to obtain a reagent; The method for using the medicament comprises the following steps: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum into water with a solid-liquid ratio of phosphogypsum to water of 1:3, add reagents according to the proportion, and introduce ammonia gas, with a molar ratio of ammonia gas, phosphogypsum and sodium carbonate in the reagent of 0.7:1:1.1, and stir at room temperature and pressure for 48 hours until the reaction is completed; S3. Centrifuge the liquid after the reaction for solid-liquid separation at a speed of 600r / min to obtain a solution rich in nutrient elements and solid particles. The separated solution was analyzed for sulfate content using a barium sulfate weight method to determine the conversion rate of sulfur element, and the solid chitosan particles were dissolved and then the calcium carbonate solid was filtered out. The purity of the calcium carbonate was calculated by high-temperature heating and decomposition. The test results of each embodiment and comparative example are shown in Tables 1 to 6. Table 1 Effect of different mass ratios of chitosan and epichlorohydrin on conversion results Table 2 Effect of different mass ratios of sodium lignin sulfonate, piperazine and trimesoyl chloride on conversion results Table 3 Effect of different solid-liquid ratios of phosphogypsum and water on conversion results Table 4 Effect of different molar ratios of ammonia, phosphogypsum and ammonium carbonate on conversion results Table 5 Effect of cationic membrane on microsphere surface on conversion results Table 6 Effect of adding different carbonates on conversion results In summary, the agent provided by the present invention can effectively promote the conversion and recovery of calcium and sulfur elements in phosphogypsum, and the operation process can be carried out at normal temperature and pressure, with a wide range of adaptability, achieving the reduction of phosphogypsum, and having good economic and environmental benefits.

Claims

1. A reagent for reducing and converting phosphogypsum, characterized in that: The agent is composed of ammonium carbonate, chitosan and epichlorohydrin. Chitosan and epichlorohydrin are cross-linked to form porous microspheres. Ammonium carbonate is loaded in the microspheres, and a negatively charged cation exchange membrane is provided on the surface of the microspheres.

2. The agent for reducing and converting phosphogypsum according to claim 1, characterized in that: The preparation method of the medicament comprises the following steps: S11. Ammonium carbonate and chitosan were added to water, carbon dioxide was introduced and stirred to dissolve, and liquid paraffin and a surfactant were slowly dripped and stirred to emulsify to obtain an ammonium carbonate - chitosan emulsion; S12. epichlorohydrin and a base were added to the ammonium carbonate-chitosan emulsion, heated and stirred for reaction, filtered, washed and freeze-dried to obtain porous microspheres loaded with ammonium carbonate; S13. The porous microspheres loaded with ammonium carbonate are immersed in an aqueous solution containing sodium lignin sulfonate and piperazine, taken out to absorb the water, and then immersed in a n-hexane solution containing trimesoyl chloride to carry out a polymerization reaction, taken out, dried and washed to obtain a drug.

3. The agent for reducing and converting phosphogypsum according to claim 2, characterized in that: In step S11, the mass ratio of chitosan to epichlorohydrin is 1:0.5-0.7, and the heating temperature is 50-70°C.

4. The agent for reducing and converting phosphogypsum according to claim 2, characterized in that: In step S13, the mass ratio of sodium lignin sulfonate, piperazine and trimesoyl chloride is 1-2:1-2:

1.

5. The method for using the agent for reducing phosphogypsum according to claim 1, characterized in that: The following steps are involved: S1. crushing the phosphogypsum, screening out phosphogypsum particles of 200 to 400 mesh, and performing harmless treatment; S2. Add the treated phosphogypsum to water, add the reagent in proportion, introduce ammonia, and stir at room temperature and pressure until the reaction is complete; S3. The liquid after the reaction is subjected to solid-liquid centrifugal separation to obtain a solution rich in nutrient elements and solid particles.

6. The method for using the agent for reducing phosphogypsum according to claim 5, characterized in that: In step S2, the solid-liquid ratio of phosphogypsum to water is 1:2-4, the molar ratio of ammonia, phosphogypsum and ammonium carbonate in the agent is 0.5-0.9:1:1-1.2, and the stirring time is 45-50 hours.

7. The method for using the agent for reducing phosphogypsum according to claim 5, characterized in that: The centrifugal separation speed in step S3 is 500-800 r / min.

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