Method for recovering valuable components through synergy of phosphogypsum and waste incineration fly ash

Abstract

The invention provides a method for recovering valuable components from ardealite and waste incineration fly ash, which comprises the following steps: uniformly mixing ardealite and waste incineration fly ash according to a certain mass, aging, mixing with water, adjusting the pH value of the mixed solution by using the waste incineration fly ash, and separating calcium sulfate and insoluble phosphorus fluorine calcium salt through multistage pulse water flow; the obtained calcium sulfate is deeply purified through a leaching-thermal analysis method to obtain ultra-pure calcium sulfate, the insoluble phosphorus-fluorine calcium salt is deeply separated through a flotation method to obtain calcium fluoride and calcium phosphate, and valuable components in the two types of solid waste are recycled.

Description

Technical Field

[0001] This invention relates to the field of solid waste treatment and reuse technology, specifically to a method for recovering valuable components from fly ash of waste incineration in conjunction with phosphogypsum. Background Technology

[0002] Phosphogypsum is a solid waste generated during the wet-process phosphoric acid production. It is reported that 4-5 tons of phosphogypsum are produced as a byproduct for every ton of phosphoric acid produced. Currently, my country's annual phosphogypsum production has reached 80 million tons, with accumulated stockpiles exceeding 800 million tons. Although calcium sulfate dihydrate is the main phase of phosphogypsum, its strong acidity and high content of soluble phosphorus and fluorine make it highly susceptible to polluting groundwater systems, necessitating harmless treatment before discharge or utilization. Currently, the resource utilization of phosphogypsum mainly focuses on its calcium sulfate content, neglecting the recovery of valuable components such as phosphorus and fluorine. However, due to limitations in product added value and transportation radius, the proportion of resource utilization is low, and stockpiling remains the primary method of disposal. This method not only occupies a large amount of land resources and wastes resources but also poses a serious threat to the surrounding ecological environment. To reduce the environmental harm caused by stockpiled phosphogypsum, alkaline substances such as quicklime and carbide slag are commonly used for harmless treatment: neutralizing acidic components and solidifying soluble phosphorus and fluorine. However, due to the low efficiency of solid-solid reactions and large fluctuations in the chemical composition of phosphogypsum, the amount of curing agent added is large, resulting in high reagent costs. Furthermore, excessive curing agent addition hinders the recovery of valuable components from phosphogypsum. Therefore, promoting low-cost, harmless treatment of phosphogypsum and the tiered recovery of its valuable components is of practical significance. Waste incineration fly ash, an alkaline powdery solid waste rich in calcium components such as CaO, CaCl2, and CaClOH, produced during waste incineration, can replace alkaline substances such as quicklime, reducing neutralization costs and solving the problem of high costs in the harmless treatment of phosphogypsum. Simultaneously, soluble calcium salts in waste incineration fly ash can dissolve in solution systems, releasing CaO. 2+ It combines with soluble phosphorus and fluorine to generate high-value, insoluble compounds such as calcium fluoride and calcium phosphate, thereby improving the recovery level of valuable components in phosphogypsum.

[0003] Based on this, the present invention provides a method for co-processing phosphogypsum and waste incineration fly ash to recover valuable components, thereby simultaneously recovering valuable components. Summary of the Invention

[0004] Based on the above description, the present invention provides a method for recovering valuable components from fly ash of phosphogypsum in conjunction with waste incineration, in order to solve the technical problem of insufficient recovery of valuable components from phosphogypsum in the prior art.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This invention provides a method for recovering valuable components from fly ash of waste incineration in conjunction with phosphogypsum, comprising: Mix phosphogypsum with waste incineration fly ash at a certain mass and let it age. Mix the mixture with water at a certain liquid-solid ratio, and add waste incineration fly ash to adjust the pH of the mixture; A multi-stage pulsed water flow separation method is used to elute soluble salts in a mixed system, while simultaneously separating calcium sulfate from a mixture of insoluble fluorine and phosphorus. The obtained calcium sulfate was further purified by leaching-thermal precipitation to obtain ultrapure calcium sulfate; The resulting mixture of sparingly soluble fluorine and phosphorus was further separated by flotation to obtain calcium fluoride and calcium phosphate.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, the mixing and aging of phosphogypsum and waste incineration fly ash at a certain mass refers to the vigorous mixing of fresh phosphogypsum (pH 2-3, moisture 20%-25%), a byproduct of the wet-process phosphoric acid process, and waste incineration fly ash (pH 11-13, moisture 15%-18%), produced by the grate furnace waste incineration power generation process, at a mass ratio of 19:1 to 99:1. After uniform mixing, the mixture is unloaded and aged for 5-8 days. The aging process refers to piling up the mixture of phosphogypsum and waste incineration fly ash.

[0008] Furthermore, the step of mixing the mixture with water at a certain liquid-solid ratio and adding waste incineration fly ash to adjust the pH of the mixture specifically includes: mixing the mixture with water, controlling the liquid-solid ratio to be 3:1 to 5:1, continuing to add waste incineration fly ash to the mixed solution, adjusting the pH of the mixed solution to 8 to 9, and simultaneously realizing the conversion of soluble phosphorus and fluorine in phosphogypsum into insoluble phosphorus and fluorine.

[0009] Furthermore, the multi-stage pulsed water flow separation method is used to elute soluble salts in the mixed system, while simultaneously separating calcium sulfate from sparingly soluble fluorine and phosphorus. Specifically, this includes: The pH-adjusted mixed solution is passed into an air-pulsating jig with a multi-chamber structure, where soluble chloride salts such as CaCl2, NaCl, and KCl are washed away by pulsating water flow. The multi-stage pulsating water flow method is used to separate calcium sulfate from insoluble fluorine and phosphorus in the mixture.

[0010] Multi-stage refers to the use of two-stage pulsed water flow for the segmented separation of calcium sulfate, gangue, and insoluble phosphorus and fluoride. Specifically, the first stage is set with a water flow rate of 60–80 times / minute and a stroke of 20–40 mm, and the second stage has a water flow rate of 45–65 times / minute and a stroke of 30–50 mm. Through the action of the two-stage pulsed water flow, soluble chloride salts such as CaCl2, NaCl, and KCl in the mixture are washed away. Calcium sulfate is recovered from the overflow of the first stage, gangue is recovered from the overflow of the second stage, and insoluble phosphorus and fluoride are recovered from the underflow.

[0011] Furthermore, the obtained calcium sulfate is further purified by a leaching-thermal precipitation method, specifically including: The overflow recovered calcium sulfate is effectively dissolved by one or more mixed chelating agents such as hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid, and sodium tripolyphosphate to form a calcium-rich solution. The solution and undissolved tailings are separated and concentrated by vacuum diaphragm pressure filtration. The solution is then decomplexed and crystallized under heating conditions of 30℃~50℃ to obtain high-purity calcium sulfate crystals.

[0012] Furthermore, the sparingly soluble fluorine and phosphorus mixture is further separated by flotation, specifically including: Using phosphate collectors (dosage 150g / t~220g / t) and water glass depressants (dosage 80g / t~120g / t) as the main flotation reagents, calcium fluoride and calcium phosphate are recovered respectively under the condition of pulp concentration of 25%~40%.

[0013] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: This invention provides a method for recovering valuable components from phosphogypsum and waste incineration fly ash. First, fresh phosphogypsum and waste incineration fly ash are mixed to achieve mineralization and solidification of soluble phosphorus and fluoride in the phosphogypsum, and acid-base neutralization. Next, the mixture is mixed with water, and the pH of the mixture is adjusted using waste incineration fly ash to effectively dissolve soluble salts in both the phosphogypsum and fly ash. Then, a multi-stage pulsed water flow separation method is used to separate insoluble calcium sulfate and the mixture of calcium fluoride and calcium phosphate. Next, leaching-thermal precipitation is used to purify calcium sulfate to obtain ultra-high purity calcium sulfate. Finally, flotation is used to achieve deep separation of calcium fluoride and calcium phosphate. This method achieves the goal of recovering valuable components from phosphogypsum and waste incineration fly ash.

[0014] Compared with existing technologies, the advantages of the technical solution of this invention are as follows: 1. This invention utilizes the properties of phosphogypsum being strongly acidic and waste incineration fly ash being rich in calcium-containing alkaline substances. Through the effective combination of the two, acid-base neutralization is achieved, while effectively mineralizing and solidifying the soluble phosphorus and fluorine in phosphogypsum that are prone to polluting the environment, thus achieving the preliminary stabilization treatment of polluting components.

[0015] 2. This method utilizes the differences in physical properties such as density and particle size of calcium sulfate, calcium fluoride, and calcium phosphate to achieve preliminary separation of the three through multi-stage pulsed water flow. It also removes soluble salts from phosphogypsum and waste incineration fly ash, thus initially purifying calcium sulfate. Subsequently, it is further purified through leaching-thermal analysis technology to obtain ultra-high purity calcium sulfate, which can be used as a high-end packing material. Utilizing the difference in surface potential of calcium fluoride and calcium phosphate, effective separation is achieved through flotation, ultimately achieving the goal of recovering valuable components from phosphogypsum and waste incineration fly ash. Detailed Implementation

[0016] Example 1 Phosphogypsum (pH 2.18, moisture 20%) and waste incineration fly ash (pH 13, moisture 15%) were vigorously mixed at a mass ratio of 19:1. After thorough mixing, the mixture was unloaded and aged for 5 days. The aged mixture was then mixed with water, maintaining a liquid-to-solid ratio of 3:1. Waste incineration fly ash was continuously added to the mixture to adjust the pH to 8. The pH-adjusted mixture was then passed into an air-pulsating jig for a two-stage pulsed water flow process. The first stage was set with a water flow rate of 60 times / minute and a stroke of 40... The second stage of water flow has a stroke rate of 45 times / minute and a stroke of 50mm. The first stage overflow recovers calcium sulfate, the second stage overflow recovers gangue, and the underflow recovers insoluble phosphorus and fluoride. A mixed chelating agent of hydroxyethylidene diphosphonic acid and ethylenediaminetetramethylenephosphonic acid is used to effectively dissolve the calcium sulfate recovered from the overflow, forming a calcium-rich solution. The solution and undissolved tailings are separated and concentrated by vacuum diaphragm pressure filtration. The solution is then decomplexed and crystallized at 30℃ to obtain high-purity calcium sulfate crystals. Using phosphate collectors (220g / t) and water glass depressants (80g / t) as the main flotation reagents, and under a pulp concentration of 30%, a "one rougher, three cleaner" separation mode is used to recover calcium fluoride and calcium phosphate respectively. The final purity of the obtained calcium sulfate is 99.72%, the purity of calcium fluoride is 87.45%, and the purity of calcium phosphate is 90.33%.

[0017] Example 2 Phosphogypsum (pH 2.18, moisture 20%) and waste incineration fly ash (pH 13, moisture 15%) were vigorously mixed at a mass ratio of 19:1. After thorough mixing, the mixture was unloaded and aged for 5 days. The aged mixture was then mixed with water, maintaining a liquid-to-solid ratio of 3:1. Waste incineration fly ash was continuously added to the mixture to adjust the pH to 8. The pH-adjusted mixture was then passed into an air-pulsating jig for a two-stage pulsed water flow process. The first stage was set with a water flow rate of 80 times / minute and a stroke of 20... The second stage of water flow has a stroke rate of 45 times / minute and a stroke of 50mm. The first stage overflow recovers calcium sulfate, the second stage overflow recovers gangue, and the underflow recovers insoluble phosphorus and fluoride. A mixed chelating agent of hydroxyethylidene diphosphonic acid and ethylenediaminetetramethylenephosphonic acid is used to effectively dissolve the calcium sulfate recovered from the overflow, forming a calcium-rich solution. The solution and undissolved tailings are separated and concentrated by vacuum diaphragm pressure filtration. The solution is then decomplexed and crystallized at 30℃ to obtain high-purity calcium sulfate crystals. Using phosphate collectors (220g / t) and water glass depressants (80g / t) as the main flotation reagents, and under a pulp concentration of 30%, a "one rougher, three cleaner" separation mode is used to recover calcium fluoride and calcium phosphate respectively. The final purity of the obtained calcium sulfate is 98.31%, the purity of calcium fluoride is 85.93%, and the purity of calcium phosphate is 87.64%.

[0018] Example 3 Phosphogypsum (pH 2.18, 20% moisture) and waste incineration fly ash (pH 13, 15% moisture) were vigorously mixed at a mass ratio of 19:1. After thorough mixing, the mixture was unloaded and aged for 10 days. The aged mixture was then mixed with water, maintaining a liquid-to-solid ratio of 3:1. Waste incineration fly ash was continuously added to the mixture to adjust the pH to 8. The pH-adjusted mixture was then passed through an air-pulsating jig for a two-stage pulsed water flow process. The first stage was set with a water flow rate of 60 times / minute and a stroke of 40mm, while the second stage was set with a water flow rate of 65 times / minute and a stroke of 30mm. The process involves recovering calcium sulfate from the overflow stage, gangue from the second overflow stage, and insoluble phosphorus and fluoride from the underflow. A chelating agent composed of hydroxyethylidene diphosphonic acid and ethylenediaminetetramethylenephosphonic acid is used to effectively dissolve the recovered calcium sulfate, forming a calcium-rich solution. This solution, along with undissolved tailings, is separated and concentrated via vacuum diaphragm filtration. The solution is then decomplexed and crystallized at 30°C to obtain high-purity calcium sulfate crystals. Using phosphate collectors (220 g / t) and water glass depressants (80 g / t) as the main flotation reagents, and with a pulp concentration of 30%, a "one-roughing, three-cleansing" separation process is employed to recover calcium fluoride and calcium phosphate. The final purity of the obtained calcium sulfate is 99.53%, calcium fluoride is 89.27%, and calcium phosphate is 91.92%.

[0019] Example 4 Phosphogypsum (pH 2.18, moisture 20%) and waste incineration fly ash (pH 13, moisture 15%) were vigorously mixed at a mass ratio of 19:1. After thorough mixing, the mixture was unloaded and aged for 10 days. The aged mixture was then mixed with water, maintaining a liquid-to-solid ratio of 3:1. Waste incineration fly ash was continuously added to the mixture to adjust the pH to 8. The pH-adjusted mixture was then passed through an air-pulsating jig for a two-stage pulsed water flow process. The first stage was set with a water flow rate of 80 times / minute and a stroke of 20mm, while the second stage had a water flow rate of 65 times / minute and a stroke of 30mm. The process involves recovering calcium sulfate from the first overflow, gangue from the second overflow, and insoluble phosphorus and fluoride from the underflow. A chelating agent composed of hydroxyethylidene diphosphonic acid and ethylenediaminetetramethylenephosphonic acid is used to effectively dissolve the recovered calcium sulfate, forming a calcium-rich solution. This solution, along with undissolved tailings, is separated and concentrated via vacuum diaphragm filtration. The solution is then decomplexed and crystallized at 30°C to obtain high-purity calcium sulfate crystals. Using phosphate collectors (220 g / t) and water glass depressants (80 g / t) as the main flotation reagents, and with a pulp concentration of 30%, a "one-roughing, three-cleansing" separation process is employed to recover calcium fluoride and calcium phosphate. The final purity of the obtained calcium sulfate is 97.79%, calcium fluoride is 86.35%, and calcium phosphate is 89.23%.

[0020] Example 5 Phosphogypsum (pH 2.18, moisture 20%) and waste incineration fly ash (pH 13, moisture 15%) were vigorously mixed at a mass ratio of 19:1. After thorough mixing, the mixture was unloaded and aged for 10 days. The aged mixture was then mixed with water, maintaining a liquid-to-solid ratio of 3:1. Waste incineration fly ash was continuously added to the mixture to adjust the pH to 8. The pH-adjusted mixture was then passed through an air-pulsating jig for a two-stage pulsed water flow process. The first stage was set with a water flow rate of 60 times / minute and a stroke of 40mm, while the second stage was set with a water flow rate of 45 times / minute and a stroke of 50mm. The process involves recovering calcium sulfate from the overflow stage, gangue from the second overflow stage, and insoluble phosphorus and fluoride from the underflow. A chelating agent composed of hydroxyethylidene diphosphonic acid and ethylenediaminetetramethylenephosphonic acid is used to effectively dissolve the recovered calcium sulfate, forming a calcium-rich solution. This solution, along with undissolved tailings, is separated and concentrated via vacuum diaphragm filtration. The solution is then decomplexed and crystallized at 30°C to obtain high-purity calcium sulfate crystals. Using phosphate collectors (150 g / t) and water glass depressants (120 g / t) as the main flotation reagents, and with a pulp concentration of 30%, a "one-roughing, three-cleansing" separation method is employed to recover calcium fluoride and calcium phosphate. The final purity of the obtained calcium sulfate is 98.87%, calcium fluoride is 84.31%, and calcium phosphate is 86.73%.

[0021] Example 6 Phosphogypsum (pH 3, moisture 18%) and waste incineration fly ash (pH 11, moisture 13%) were vigorously mixed at a mass ratio of 99:1. After thorough mixing, the mixture was unloaded and aged for 8 days. The aged mixture was then mixed with water, maintaining a liquid-to-solid ratio of 3:1. Waste incineration fly ash was continuously added to the mixture to adjust the pH to 8. The pH-adjusted mixture was then passed into an air-pulsating jig for a two-stage pulsed water flow process. The first stage was set with a water flow rate of 60 times / minute and a stroke of 40... The second stage of water flow has a stroke rate of 45 times / minute and a stroke of 50mm. The first stage overflow recovers calcium sulfate, the second stage overflow recovers gangue, and the underflow recovers insoluble phosphorus and fluoride. A mixed chelating agent of hydroxyethylidene diphosphonic acid and ethylenediaminetetramethylenephosphonic acid is used to effectively dissolve the calcium sulfate recovered from the overflow, forming a calcium-rich solution. The solution and undissolved tailings are separated and concentrated by vacuum diaphragm pressure filtration. Under heating at 30℃, the complexation is de-complexed and crystallized to obtain high-purity calcium sulfate crystals. Using phosphate collectors (220g / t) and water glass inhibitors (80g / t) as the main flotation reagents, and with a pulp concentration of 30%, a "one rougher, three cleaner" separation mode is used to recover calcium fluoride and calcium phosphate respectively. The final purity of the obtained calcium sulfate is 99.51%, the purity of calcium fluoride is 89.66%, and the purity of calcium phosphate is 92.95%.

[0022] Example 7 Phosphogypsum (pH 3, moisture 18%) and waste incineration fly ash (pH 11, moisture 13%) were vigorously mixed at a mass ratio of 99:1. After thorough mixing, the mixture was unloaded and aged for 8 days. The aged mixture was then mixed with water, maintaining a liquid-to-solid ratio of 3:1. Waste incineration fly ash was continuously added to the mixture to adjust the pH to 8. The pH-adjusted mixture was then passed into an air-pulsating jig for a two-stage pulsed water flow process. The first stage was set with a water flow rate of 60 times / minute and a stroke of 40... The second stage of water flow has a stroke rate of 45 times / minute and a stroke of 50mm. The first stage overflow recovers calcium sulfate, the second stage overflow recovers gangue, and the underflow recovers insoluble phosphorus and fluoride. A mixed chelating agent of hydroxyethylidene diphosphonic acid and ethylenediaminetetramethylenephosphonic acid is used to effectively dissolve the calcium sulfate recovered from the overflow, forming a calcium-rich solution. The solution and undissolved tailings are separated and concentrated by vacuum diaphragm pressure filtration. Under heating at 50℃, the complexation is de-complexed and crystallized to obtain high-purity calcium sulfate crystals. Using phosphate collectors (220g / t) and water glass depressants (80g / t) as the main flotation reagents, and with a pulp concentration of 30%, a "one rougher, three cleaner" separation mode is used to recover calcium fluoride and calcium phosphate respectively. The final purity of the obtained calcium sulfate is 96.08%, the purity of calcium fluoride is 90.37%, and the purity of calcium phosphate is 92.68%.

[0023] Example 8 Phosphogypsum (pH 3, moisture 18%) and waste incineration fly ash (pH 11, moisture 13%) were vigorously mixed at a mass ratio of 99:1. After thorough mixing, the mixture was unloaded and aged for 8 days. The aged mixture was then mixed with water, maintaining a liquid-to-solid ratio of 3:1. Waste incineration fly ash was continuously added to the mixture to adjust the pH to 8. The pH-adjusted mixture was then passed into an air-pulsating jig for a two-stage pulsed water flow process. The first stage was set with a water flow rate of 60 times / minute and a stroke of 40... The second stage of water flow has a stroke rate of 45 times / minute and a stroke of 50mm. The first stage overflow recovers calcium sulfate, the second stage overflow recovers gangue, and the underflow recovers insoluble phosphorus and fluoride. A mixed chelating agent of hydroxyethylidene diphosphonic acid and ethylenediaminetetramethylenephosphonic acid is used to effectively dissolve the calcium sulfate recovered from the overflow, forming a calcium-rich solution. The solution and undissolved tailings are separated and concentrated by vacuum diaphragm pressure filtration. Under heating at 30℃, the complexation is de-complexed and crystallized to obtain high-purity calcium sulfate crystals. Using phosphate collectors (150g / t) and water glass depressants (120g / t) as the main flotation reagents, and with a pulp concentration of 30%, a "one rougher, three cleaner" separation mode is used to recover calcium fluoride and calcium phosphate respectively. The final purity of the obtained calcium sulfate is 99.31%, the purity of calcium fluoride is 87.85%, and the purity of calcium phosphate is 90.40%.

[0024] Comparative Example 1 Phosphogypsum (pH 2.18, moisture 20%) and waste incineration fly ash (pH 13, moisture 15%) were vigorously mixed at a mass ratio of 7:3. After thorough mixing, the mixture was unloaded and aged for 1 day. The aged mixture was then mixed with water, maintaining a liquid-to-solid ratio of 3:1. Waste incineration fly ash was continuously added to the mixture to adjust the pH to 8. The pH-adjusted mixture was then passed into an air-pulsating jig for a two-stage pulsed water flow process. The first stage was set with a water flow rate of 50 times / minute and a stroke of 50... The second stage of water flow has a stroke rate of 40 times / minute and a stroke of 60mm. The overflow from the first stage recovers calcium sulfate, the overflow from the second stage recovers gangue, and the underflow recovers insoluble phosphorus and fluoride. A mixed chelating agent of hydroxyethylidene diphosphonic acid and ethylenediaminetetramethylenephosphonic acid is used to effectively dissolve the calcium sulfate recovered from the overflow, forming a calcium-rich solution. The solution and undissolved tailings are separated and concentrated by vacuum diaphragm pressure filtration. The solution is then decomplexed and crystallized at 60℃ to obtain high-purity calcium sulfate crystals. Using phosphate collectors (140g / t) and water glass depressants (130g / t) as the main flotation reagents, and under a pulp concentration of 45%, a "one rougher, three cleaner" separation mode is used to recover calcium fluoride and calcium phosphate respectively. The final purity of the obtained calcium sulfate is 87.65%, the purity of calcium fluoride is 54.93%, and the purity of calcium phosphate is 60.35%.

[0025] Comparative Example 2 The steps are the same as in Example 1, except that the two-stage pulse conditions are: the first stage is set with a water flow rate of 40 times / minute and a stroke of 10mm, and the second stage is set with a water flow rate of 40 times / minute and a stroke of 20mm. The final obtained calcium sulfate has a purity of 90.73%, calcium fluoride has a purity of 70.65%, and calcium phosphate has a purity of 65.74%.

[0026] Comparative Example 3 The steps are the same as in Example 1, except that the phosphogypsum and waste incineration fly ash are mixed at a mass ratio of 10:1. The final calcium sulfate has a purity of 91.60%, calcium fluoride has a purity of 62.83%, and calcium phosphate has a purity of 72.46%.

Claims

1. A method for recovering valuable components from fly ash of waste incineration in conjunction with phosphogypsum, characterized in that, Includes the following steps: (1) Mix phosphogypsum with waste incineration fly ash and age it; (2) Mix the aged mixture with water and adjust the pH to the alkaline range; (3) A multi-stage pulsed water flow separation method is used to elute soluble salts in the mixed system, while simultaneously separating calcium sulfate from insoluble fluorine and phosphorus; (4) The separated calcium sulfate is purified by leaching and thermal precipitation to obtain high-purity calcium sulfate; (5) The sparingly soluble calcium fluoride salts are separated by flotation to obtain calcium fluoride and calcium phosphate.

2. The method according to claim 1, characterized in that, The phosphogypsum is a byproduct of the wet-process phosphoric acid production process with a pH of 2-3; the waste incineration fly ash is an alkaline hazardous waste generated during waste incineration with a pH of 11-13.

3. The method according to claim 1, characterized in that, The mixing mass ratio of the phosphogypsum to the fly ash from waste incineration is 19:1 to 99:1, and the aging time is 5 to 10 days.

4. The method according to claim 1, characterized in that, In step (2), the liquid-solid ratio of the mixture to water is 3:1 to 5:1, and the pH is adjusted to 8 to 9.

5. The method according to claim 1, characterized in that, The multi-stage pulsed water flow separation method includes at least two pulsed water flows, and the number and stroke of each flow can be independently adjusted to achieve the segmented separation of calcium sulfate, gangue and insoluble calcium fluoride salts.

6. The method according to claim 5, characterized in that, In the multi-stage pulse water flow separation method: The first stage of pulsed water flow has a frequency of 60-80 times / minute and a stroke of 20-40 mm, and calcium sulfate is recovered through overflow; The second stage of pulsed water flow has a frequency of 45 to 65 times per minute and a stroke of 30 to 50 mm. It recovers gangue through overflow and insoluble phosphorus and fluorine through underflow.

7. The method according to claim 1, characterized in that, In the leaching-heat purification step, calcium sulfate is dissolved using one or more chelating agents to form a calcium-rich solution. After concentration, the solution is heated to crystallize and obtain calcium sulfate crystals with a purity higher than 99%. The chelating agent is selected from one or more of hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid, and sodium tripolyphosphate.

8. The method according to claim 7, characterized in that, In the flotation separation step, a composite reagent system consisting of a phosphoric acid collector and a water glass inhibitor is used to carry out flotation separation under the condition of a pulp concentration of 25% to 40%. The amount of collector used is 150 to 220 g / t, and the amount of inhibitor used is 80 to 120 g / t. The flotation process adopts a "one roughing and three cleaning" separation mode.

9. An ultrapure calcium sulfate, calcium fluoride, or calcium phosphate prepared by any one of the methods described in claims 1 to 8, characterized in that, The purity of ultrapure calcium sulfate is not less than 99.5%; the purity of calcium fluoride or calcium phosphate is not less than 85%.

10. The application of the method according to any one of claims 1 to 8 in the resource utilization of solid waste, the harmless treatment of phosphogypsum, or the comprehensive utilization of fly ash from waste incineration.