Purification method of modified phosphogypsum
By modifying the treatment of phosphogypsum micro powder, including stirring and heating and flotation steps, the problems of low utilization rate of phosphogypsum and environmental pollution are solved, the purification effect and application value of phosphogypsum are improved, and low-cost and efficient resource utilization is achieved.
Patent Information
- Application Number
- CN202411247648.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-06
- Publication Date
- 2025-01-03
AI Technical Summary
The utilization rate of phosphogypsum is mainly due to its poor surface performance, which leads to low efficiency of impurity removal methods, which affects the reuse of industrial by-product gypsum, and the accumulation of slag mountains pollute the environment.
After sieve the large piece of phosphogypsum, add sodium hardenate, calcium stearate, silane coupling agent, aluminate coupling agent, titanate coupling agent and liquid paraffin for stirring and heating. Adjust the pH value and add water and chelating agent for flotation and washing anyway to obtain a purified light gypsum.
It improves the surface performance of phosphogypsum micro powder, expands its application, has significant purification effect, removes toxic impurities, and improves the utilization value of phosphogypsum. It has a simple process and low cost.
Smart Images
Figure CN119240775A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of phosphorus chemical industry, and in particular to a method for purifying modified phosphogypsum. Background Art
[0002] Phosphogypsum is a solid waste of the phosphate fertilizer industry. Generally, about 5-6 tons of phosphogypsum are produced for every ton of phosphoric acid produced, and 2.5-5 tons of phosphogypsum are discharged for every ton of diammonium phosphate produced. At present, the comprehensive utilization rate of phosphogypsum is relatively low both at home and abroad, and it is mainly treated by stockpiling. The cumulative discharge of phosphogypsum in my country is nearly 100 million tons, which is the largest type of gypsum waste. The discharged phosphogypsum slag occupies a large amount of land, forming slag mountains, which seriously pollutes the environment. A large amount of phosphogypsum piled up into mountains not only occupies a large amount of land resources, but also contains soluble phosphorus, fluorine, organic matter and a small amount of cadmium, arsenic, mercury and other harmful heavy metal chemicals that are harmful to organisms. Long-term accumulation of these harmful substances will pollute the surrounding soil, affect vegetation growth, and seriously damage the ecological environment of the area. They will also be washed away by rainwater, analyzed by water, and flow in water bodies, and eventually enter rivers to cause water pollution.
[0003] At present, the output of phosphogypsum is very large, but its utilization rate is very low. There are many reasons for the low utilization rate of phosphogypsum, but the most important one is that the surface performance of phosphogypsum is poor, resulting in a relatively single utilization method. The impurity removal method of industrial by-product gypsum is inefficient in removing harmful impurities in phosphogypsum, which affects the reuse of industrial by-product gypsum. Summary of the invention
[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for purifying modified phosphogypsum.
[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: The present invention provides a method for purifying modified phosphogypsum, comprising the following steps: The bulk phosphogypsum is sieved and then ground to obtain phosphogypsum fine powder; The phosphogypsum powder is heated and then cooled; Adding sodium stearate and calcium stearate to the cooled phosphogypsum powder, and stirring and mixing in a stirring and heating device to obtain A; Adding a silane coupling agent and an aluminate coupling agent to A, and stirring and mixing in a stirring and heating device to obtain B; Add titanate coupling agent and liquid paraffin to B, stir and mix in a stirring and heating device, and adjust the pH value of the mixture to be alkaline to obtain C; Add an appropriate amount of water to C, and stir and mix in a stirring and heating device to obtain a slurry; After reverse flotation of the slurry, a chelating agent is added for purification and rough separation to obtain D; D is washed and filtered to obtain lightweight gypsum and tailings.
[0006] As a preferred technical solution of the present invention, the bulk phosphogypsum is sieved through 80-100 mesh and then ground to 120-150 mesh to obtain phosphogypsum fine powder.
[0007] As a preferred technical solution of the present invention, the phosphogypsum powder is irradiated with microwaves for 10-30 minutes to raise its internal temperature to 100-300°C, and then cooled to 30-50°C.
[0008] As a preferred technical solution of the present invention, the weight ratio of the cooled phosphogypsum powder, sodium stearate and calcium stearate is 100: (2-4): (3-4). After mixing, it is first stirred at 500-700 r / min for 10-20 minutes. After the temperature of the mixture drops to 20-30°C, it is heated to 100-150°C and stirred for 15-20 minutes to obtain A.
[0009] As a preferred technical solution of the present invention, the weight ratio of A, silane coupling agent and aluminate coupling agent is 100: (1-2): (0.5-1). After mixing, it is first stirred at 500-700r / min for 10-20min, and after the temperature of the mixture drops to 20-30°C, it is heated to 100-150°C and stirred for 15-20min to obtain B.
[0010] As a preferred technical solution of the present invention, the weight ratio of B, titanate coupling agent and liquid paraffin is 100: (2-2.5): (0.5-1). After mixing, it is first stirred at 500-700r / min for 10-20min, and after the temperature of the mixture drops to 20-30°C, it is heated to 100-150°C and stirred for 15-20min to obtain C with a pH value of 9.
[0011] As a preferred technical solution of the present invention, concentrated sulfuric acid with a concentration of 98% is added to the slurry as a phase change aid and flotation agent; Then add a chelating agent for extraction and rough selection to obtain D.
[0012] As a preferred technical solution of the present invention, the flotation agent comprises the following raw materials in mass percentage: 30-70% oil phase, 10-40% surfactant and 10-30% alcohol, and the introduction amount thereof is 0.2-0.5 mL / min; The chelating agent comprises the following raw materials in mass percentage: 80-90% of heavy metal chelating agent and 10-20% of flocculant, and the introduction amount thereof is 10-30 mL / min.
[0013] As a preferred technical solution of the present invention, the D is washed on a vacuum belt filter by three-stage countercurrent washing, and after washing, light gypsum and tailings are obtained by filtration.
[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention modifies the phosphogypsum powder by the above method, and the surface properties of the modified phosphogypsum powder are greatly improved, thereby expanding its industrial application and improving the utilization value of the phosphogypsum; 2. The purification effect of modified phosphogypsum powder is better. The content and whiteness of the purified gypsum are significantly increased, and various toxic impurity ions are removed, which provides a guarantee for better resource utilization of industrial by-product gypsum; 3. The method of the present invention has low equipment requirements, simple process and low cost during processing, but the effect achieved is very obvious. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 It is a flow chart of the steps of the present invention. DETAILED DESCRIPTION
[0016] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.
[0017] In the drawings, the same reference numerals all refer to the same components.
[0018] Embodiment 1: like Figure 1 As shown, the present invention provides a method for purifying modified phosphogypsum, comprising the following steps: The bulk phosphogypsum is sieved and then ground to obtain phosphogypsum fine powder; The phosphogypsum powder is heated and then cooled; Adding sodium stearate and calcium stearate to the cooled phosphogypsum powder, and stirring and mixing in a stirring and heating device to obtain A; Adding a silane coupling agent and an aluminate coupling agent to A, and stirring and mixing in a stirring and heating device to obtain B; Add titanate coupling agent and liquid paraffin to B, stir and mix in a stirring and heating device, and adjust the pH value of the mixture to be alkaline to obtain C; Add an appropriate amount of water to C, and stir and mix in a stirring and heating device to obtain a slurry; After reverse flotation of the slurry, a chelating agent is added for purification and rough separation to obtain D; D is washed and filtered to obtain lightweight gypsum and tailings.
[0019] Furthermore, the bulk phosphogypsum is sieved through 80 mesh and then ground to 120 mesh to obtain phosphogypsum fine powder.
[0020] Furthermore, the phosphogypsum powder is irradiated with microwaves for 10 minutes to raise the internal temperature to 100° C., and then cooled to 30° C.
[0021] Furthermore, the weight ratio of the cooled phosphogypsum powder, sodium stearate and calcium stearate is 100:2:3. After mixing, it is stirred at 500 r / min for 10 minutes. After the temperature of the mixture drops to 20°C, it is heated to 100°C and stirred for 15 minutes to obtain A.
[0022] Furthermore, the weight ratio of A, silane coupling agent and aluminate coupling agent is 100:1:0.5. After mixing, the mixture is stirred at 500 r / min for 10 minutes. After the mixture temperature drops to 20°C, it is heated to 100°C and stirred for 15 minutes to obtain B.
[0023] Furthermore, the weight ratio of B, titanate coupling agent and liquid paraffin is 100:2:0.5. After mixing, it is stirred at 500r / min for 10 minutes. After the temperature of the mixture drops to 20°C, it is heated to 100°C and stirred for 15 minutes to obtain C with a pH value of 9.
[0024] Further, adding 98% concentrated sulfuric acid to the slurry as a phase change aid and flotation agent; Then add a chelating agent for extraction and rough selection to obtain D.
[0025] Further, the flotation agent comprises the following raw materials in mass percentage: 70% oil phase, 10% surfactant and 20% alcohol, and the introduction amount thereof is 0.2 mL / min; The chelating agent comprises the following raw materials in percentage by weight: 80% of a heavy metal chelating agent and 20% of a flocculant, and the introduction amount thereof is 10 mL / min.
[0026] Furthermore, the D is washed on a vacuum belt filter by three-stage countercurrent washing, and after washing, light gypsum and tailings are obtained by filtration.
[0027] Embodiment 2: like Figure 1As shown, the present invention provides a method for purifying modified phosphogypsum, comprising the following steps: The bulk phosphogypsum is sieved and then ground to obtain phosphogypsum fine powder; The phosphogypsum powder is heated and then cooled; Adding sodium stearate and calcium stearate to the cooled phosphogypsum powder, and stirring and mixing in a stirring and heating device to obtain A; Adding a silane coupling agent and an aluminate coupling agent to A, and stirring and mixing in a stirring and heating device to obtain B; Add titanate coupling agent and liquid paraffin to B, stir and mix in a stirring and heating device, and adjust the pH value of the mixture to be alkaline to obtain C; Add an appropriate amount of water to C, and stir and mix in a stirring and heating device to obtain a slurry; After reverse flotation of the slurry, a chelating agent is added for purification and rough separation to obtain D; D is washed and filtered to obtain lightweight gypsum and tailings.
[0028] Furthermore, the bulk phosphogypsum is sieved through 100 mesh and then ground to 150 mesh to obtain phosphogypsum fine powder.
[0029] Furthermore, the phosphogypsum powder is irradiated with microwaves for 30 minutes to raise the internal temperature to 300° C., and then cooled to 50° C.
[0030] Furthermore, the weight ratio of the cooled phosphogypsum powder, sodium stearate and calcium stearate is 100:4:4. After mixing, it is stirred at 700 r / min for 20 minutes. After the temperature of the mixture drops to 30°C, it is heated to 150°C and stirred for 20 minutes to obtain A.
[0031] Furthermore, the weight ratio of A, silane coupling agent and aluminate coupling agent is 100: 2: 1. After mixing, the mixture is stirred at 700 r / min for 20 minutes. After the temperature of the mixture drops to 30° C., it is heated to 150° C. and stirred for 20 minutes to obtain B.
[0032] Furthermore, the weight ratio of B, titanate coupling agent and liquid paraffin is 100:2.5:1. After mixing, it is stirred at 700r / min for 20min. After the temperature of the mixture drops to 30°C, it is heated to 150°C and stirred for 20min to obtain C with a pH value of 9.
[0033] Further, adding 98% concentrated sulfuric acid to the slurry as a phase change aid and flotation agent; Then add a chelating agent for extraction and rough selection to obtain D.
[0034] Further, the flotation agent includes the following raw materials in mass percentage: 70% oil phase, 20% surfactant and 10% alcohol, and the introduction amount thereof is 0.5 mL / min; The chelating agent comprises the following raw materials in mass percentage: 90% of heavy metal chelating agent and 10% of flocculant, and the introduction amount thereof is 30 mL / min.
[0035] Furthermore, the D is washed on a vacuum belt filter by three-stage countercurrent washing, and after washing, light gypsum and tailings are obtained by filtration.
[0036] Embodiment 3: like Figure 1 As shown, the present invention provides a method for purifying modified phosphogypsum, comprising the following steps: The bulk phosphogypsum is sieved and then ground to obtain phosphogypsum fine powder; The phosphogypsum powder is heated and then cooled; Adding sodium stearate and calcium stearate to the cooled phosphogypsum powder, and stirring and mixing in a stirring and heating device to obtain A; Adding a silane coupling agent and an aluminate coupling agent to A, and stirring and mixing in a stirring and heating device to obtain B; Add titanate coupling agent and liquid paraffin to B, stir and mix in a stirring and heating device, and adjust the pH value of the mixture to be alkaline to obtain C; Add an appropriate amount of water to C, and stir and mix in a stirring and heating device to obtain a slurry; After reverse flotation of the slurry, a chelating agent is added for purification and rough separation to obtain D; D is washed and filtered to obtain lightweight gypsum and tailings.
[0037] Furthermore, the bulk phosphogypsum is sieved through 85 mesh and then ground to 130 mesh to obtain phosphogypsum fine powder.
[0038] Furthermore, the phosphogypsum powder is irradiated with microwaves for 15 minutes to raise the internal temperature to 150° C., and then cooled to 20° C.
[0039] Furthermore, the weight ratio of the cooled phosphogypsum powder, sodium stearate and calcium stearate is 100:3:3. After mixing, it is stirred at 550 r / min for 13 minutes. After the temperature of the mixture drops to 22°C, it is heated to 125°C and stirred for 17 minutes to obtain A.
[0040] Furthermore, the weight ratio of A, silane coupling agent and aluminate coupling agent is 100:1:0.7. After mixing, the mixture is stirred at 600 r / min for 15 minutes. After the temperature of the mixture drops to 25°C, it is heated to 120°C and stirred for 18 minutes to obtain B.
[0041] Furthermore, the weight ratio of B, titanate coupling agent and liquid paraffin is 100:2.2:0.9. After mixing, it is stirred at 650r / min for 15 minutes. After the temperature of the mixture drops to 250°C, it is heated to 145°C and stirred for 15 minutes to obtain C with a pH value of 9.
[0042] Further, adding 98% concentrated sulfuric acid to the slurry as a phase change aid and flotation agent; Then add a chelating agent for extraction and rough selection to obtain D.
[0043] Further, the flotation agent comprises the following raw materials in mass percentage: 65% oil phase, 15% surfactant and 20% alcohol, and the introduction amount thereof is 0.4 mL / min; The chelating agent comprises the following raw materials in percentage by weight: 85% of heavy metal chelating agent and 15% of flocculant, and the introduction amount thereof is 15 mL / min.
[0044] Furthermore, the D is washed on a vacuum belt filter by three-stage countercurrent washing, and after washing, light gypsum and tailings are obtained by filtration.
[0045] Embodiment 4: like Figure 1 As shown, the present invention provides a method for purifying modified phosphogypsum, comprising the following steps: The bulk phosphogypsum is sieved and then ground to obtain phosphogypsum fine powder; The phosphogypsum powder is heated and then cooled; Adding sodium stearate and calcium stearate to the cooled phosphogypsum powder, and stirring and mixing in a stirring and heating device to obtain A; Adding a silane coupling agent and an aluminate coupling agent to A, and stirring and mixing in a stirring and heating device to obtain B; Add titanate coupling agent and liquid paraffin to B, stir and mix in a stirring and heating device, and adjust the pH value of the mixture to be alkaline to obtain C; Add an appropriate amount of water to C, and stir and mix in a stirring and heating device to obtain a slurry; After reverse flotation of the slurry, a chelating agent is added for purification and rough separation to obtain D; D is washed and filtered to obtain lightweight gypsum and tailings.
[0046] Furthermore, the bulk phosphogypsum is sieved through 90 mesh and then ground to 135 mesh to obtain phosphogypsum fine powder.
[0047] Furthermore, the phosphogypsum powder is irradiated with microwaves for 25 minutes to raise the internal temperature to 200° C., and then cooled to 40° C.
[0048] Furthermore, the weight ratio of the cooled phosphogypsum powder, sodium stearate and calcium stearate is 100:3.5:3.5. After mixing, it is stirred at 6000 r / min for 15 minutes. After the temperature of the mixture drops to 25°C, it is heated to 135°C and stirred for 20 minutes to obtain A.
[0049] Furthermore, the weight ratio of A, silane coupling agent and aluminate coupling agent is 100:1.5:0.8. After mixing, it is stirred at 600 r / min for 15 minutes. After the temperature of the mixture drops to 20°C, it is heated to 135°C and stirred for 20 minutes to obtain B.
[0050] Furthermore, the weight ratio of B, titanate coupling agent and liquid paraffin is 100:2.2:0.6. After mixing, it is stirred at 600r / min for 15min. After the temperature of the mixture drops to 30°C, it is heated to 135°C and stirred for 20min to obtain C with a pH value of 9.
[0051] Further, adding 98% concentrated sulfuric acid to the slurry as a phase change aid and flotation agent; Then add a chelating agent for extraction and rough selection to obtain D.
[0052] Further, the flotation agent includes the following raw materials in mass percentage: 60% oil phase, 30% surfactant and 10% alcohol, and the introduction amount thereof is 0.4 mL / min; The chelating agent comprises the following raw materials in percentage by weight: 80% of a heavy metal chelating agent and 20% of a flocculant, and the introduction amount thereof is 20 mL / min.
[0053] Furthermore, the D is washed on a vacuum belt filter by three-stage countercurrent washing, and after washing, light gypsum and tailings are obtained by filtration.
[0054] Embodiment 5: like Figure 1 As shown, the present invention provides a method for purifying modified phosphogypsum, comprising the following steps: The bulk phosphogypsum is sieved and then ground to obtain phosphogypsum fine powder; The phosphogypsum powder is heated and then cooled; Adding sodium stearate and calcium stearate to the cooled phosphogypsum powder, and stirring and mixing in a stirring and heating device to obtain A; Adding a silane coupling agent and an aluminate coupling agent to A, and stirring and mixing in a stirring and heating device to obtain B; Add titanate coupling agent and liquid paraffin to B, stir and mix in a stirring and heating device, and adjust the pH value of the mixture to be alkaline to obtain C; Add an appropriate amount of water to C, and stir and mix in a stirring and heating device to obtain a slurry; After reverse flotation of the slurry, a chelating agent is added for purification and rough separation to obtain D; D is washed and filtered to obtain lightweight gypsum and tailings.
[0055] Furthermore, the bulk phosphogypsum is sieved through 95 mesh and then ground to 145 mesh to obtain phosphogypsum fine powder.
[0056] Furthermore, the phosphogypsum powder is irradiated with microwaves for 25 minutes to raise the internal temperature to 250° C., and then cooled to 45° C.
[0057] Furthermore, the weight ratio of the cooled phosphogypsum powder, sodium stearate and calcium stearate is 100:3.5:4. After mixing, it is stirred at 650r / min for 20min. After the temperature of the mixture drops to 30°C, it is heated to 140°C and stirred for 20min to obtain A.
[0058] Furthermore, the weight ratio of A, silane coupling agent and aluminate coupling agent is 100:1.8:0.7. After mixing, it is stirred at 650r / min for 20 minutes. After the temperature of the mixture drops to 25°C, it is heated to 145°C and stirred for 20 minutes to obtain B.
[0059] Furthermore, the weight ratio of B, titanate coupling agent and liquid paraffin is 100:2.4:0.8. After mixing, it is stirred at 650r / min for 20 minutes. After the temperature of the mixture drops to 30°C, it is heated to 150°C and stirred for 20 minutes to obtain C with a pH value of 9.
[0060] Further, adding 98% concentrated sulfuric acid to the slurry as a phase change aid and flotation agent; Then add a chelating agent for extraction and rough selection to obtain D.
[0061] Further, the flotation agent includes the following raw materials in mass percentage: 70% oil phase, 15% surfactant and 15% alcohol, and the introduction amount thereof is 0.3 mL / min; The chelating agent comprises the following raw materials in percentage by weight: 85% of heavy metal chelating agent and 15% of flocculant, and the introduction amount thereof is 15 mL / min.
[0062] Furthermore, the D is washed on a vacuum belt filter by three-stage countercurrent washing, and after washing, light gypsum and tailings are obtained by filtration.
[0063] The invention discloses a purification method for modified phosphogypsum. The phosphogypsum powder is modified by the method, and the surface performance of the modified phosphogypsum powder is greatly improved, the industrial application of the modified phosphogypsum powder is expanded, and the utilization value of the phosphogypsum is improved. The purification effect of the modified phosphogypsum powder is better, the content and whiteness of the purified gypsum are significantly increased, and various toxic impurity ions are removed, which provides a guarantee for better resource utilization of industrial by-product gypsum. The method of the invention has low equipment requirements, simple process and low cost during processing, but the effect achieved is very obvious.
[0064] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A method for purifying modified phosphogypsum, characterized in that: The steps include: The bulk phosphogypsum is sieved and then ground to obtain phosphogypsum fine powder; The phosphogypsum powder is heated and then cooled; Adding sodium stearate and calcium stearate to the cooled phosphogypsum powder, and stirring and mixing in a stirring and heating device to obtain A; Adding a silane coupling agent and an aluminate coupling agent to A, and stirring and mixing in a stirring and heating device to obtain B; Add titanate coupling agent and liquid paraffin to B, stir and mix in a stirring and heating device, and adjust the pH value of the mixture to be alkaline to obtain C; Add an appropriate amount of water to C, and stir and mix in a stirring and heating device to obtain a slurry; After reverse flotation of the slurry, a chelating agent is added for purification and rough separation to obtain D; D is washed and filtered to obtain lightweight gypsum and tailings.
2. The method for purifying modified phosphogypsum according to claim 1, characterized in that: The bulk phosphogypsum is sieved through 80-100 mesh and then ground to 120-150 mesh to obtain phosphogypsum fine powder.
3. The method for purifying modified phosphogypsum according to claim 1, characterized in that: The phosphogypsum powder is irradiated with microwaves for 10-30 minutes to raise the internal temperature to 100-300° C., and then cooled to 30-50° C.
4. The method for purifying modified phosphogypsum according to claim 1, characterized in that: The weight ratio of the cooled phosphogypsum powder, sodium stearate and calcium stearate is 100:(2-4):(3-4). After mixing, stir at 500-700 r / min for 10-20 min. After the temperature of the mixture drops to 20-30° C., heat it to 100-150° C. and stir for 15-20 min to obtain A.
5. The method for purifying modified phosphogypsum according to claim 1, characterized in that: The weight ratio of A, silane coupling agent and aluminate coupling agent is 100: (1-2): (0.5-1). After mixing, stir at 500-700 r / min for 10-20 minutes. After the temperature of the mixture drops to 20-30° C., heat it to 100-150° C. and stir for 15-20 minutes to obtain B.
6. The method for purifying modified phosphogypsum according to claim 1, characterized in that: The weight ratio of B, titanate coupling agent and liquid paraffin is 100: (2-2.5): (0.5-1). After mixing, stir at 500-700 r / min for 10-20 minutes. After the temperature of the mixture drops to 20-30° C., heat it to 100-150° C. and stir for 15-20 minutes to obtain C with a pH value of 9.
7. The method for purifying modified phosphogypsum according to claim 1, characterized in that: Adding 98% concentrated sulfuric acid to the slurry as a phase change aid and flotation agent; Then add a chelating agent for extraction and rough selection to obtain D.
8. The method for purifying modified phosphogypsum according to claim 7, characterized in that: The flotation agent comprises the following raw materials in mass percentage: 30-70% oil phase, 10-40% surfactant and 10-30% alcohol, and the introduction amount thereof is 0.2-0.5 mL / min; The chelating agent comprises the following raw materials in mass percentage: 80-90% of heavy metal chelating agent and 10-20% of flocculant, and the introduction amount thereof is 10-30 mL / min.
9. The method for purifying modified phosphogypsum according to claim 1, characterized in that: The D is washed on a vacuum belt filter by three-stage countercurrent washing, and after washing, light gypsum and tailings are obtained by filtration.