Treatment method of phosphogypsum

Abstract

The invention provides a phosphogypsum treatment method, and belongs to the technical field of solid waste recovery and application. The method comprises the following steps: providing ingredients including 40-50% of phosphogypsum, 20-30% of quartz sand, 6-10% of sodium carbonate, 6-10% of sodium fluosilicate and 10-15% of feldspar; the ingredients are subjected to melting treatment at the temperature of 1400-1600 DEG C, and desulfurized molten glass and sulfur-containing flue gas are obtained. And sequentially carrying out cooling treatment, forming treatment and micro-crystallization treatment on the desulfurized molten glass to obtain the microcrystalline glass plate. According to the method, the operation of pretreating ardealite in the conventional ardealite treatment process is omitted, and the process flow is simple; the ardealite is efficiently utilized, the bending strength of the obtained microcrystal glass plate is up to 89 MPa, and the microcrystal glass plate can be widely applied to building decoration. The process of turning waste into wealth from phosphogypsum is promoted, and a positive contribution is made to efficient resource utilization of phosphogypsum.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste recovery and application, and in particular relates to a method for treating phosphogypsum. Background Art

[0002] Phosphogypsum is a solid waste generated primarily during the production of phosphate fertilizers and other products, and is discharged in significant quantities. Industrially, every ton of phosphoric acid produced generates approximately four to five tons of phosphogypsum. Improper handling of large amounts of this industrial solid waste can contaminate soil and water resources.

[0003] Currently, common methods for handling phosphogypsum include stockpiling and comprehensive utilization. Stockpiling requires a large amount of land and may pose a risk of leakage. In terms of comprehensive utilization, phosphogypsum can be used in building materials, such as the production of gypsum board and cement retarders, or in agricultural soil improvement. However, these applications require pretreatment of the phosphogypsum to remove harmful substances, resulting in complex processes. Therefore, how to efficiently and safely handle and utilize phosphogypsum and reduce its negative impact on the environment remains a challenge. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method for treating phosphogypsum, which aims to solve the problems of high leakage risk and complicated process flow in the existing technology of recycling and treating phosphogypsum.

[0005] To achieve the above object, the present invention provides a method for treating phosphogypsum, comprising the steps of:

[0006] Providing ingredients; the ingredients include, by mass percentage, 40-50% of phosphogypsum, 20-30% of quartz sand, 6-10% of soda ash, 6-10% of sodium fluorosilicate and 10-15% of feldspar.

[0007] The components in the batch are mixed and melted to obtain desulfurized glass liquid and sulfur-containing flue gas; the temperature of the melting treatment is 1400-1600°C.

[0008] The desulfurized glass liquid is subjected to cooling treatment, forming treatment and microcrystallization treatment in sequence to obtain a microcrystalline glass plate.

[0009] Furthermore, the batching components also include additives; the additives include antimony powder and sodium nitrate; the additives account for 1 to 5% of the batching components.

[0010] Furthermore, the melting treatment takes 480 to 500 minutes.

[0011] Furthermore, the cooling treatment is carried out by slowly cooling the desulfurized glass liquid to 1050-1150° C. to obtain a cooled liquid.

[0012] Furthermore, the forming process is to use a calender to roll the cooled liquid into a plate.

[0013] Furthermore, the slow cooling rate in the slow cooling step is 3-5°C / min.

[0014] Furthermore, the microcrystallization treatment is performed by heat treating the plate obtained by the molding treatment at 500-850° C. and cooling it to room temperature to obtain the microcrystalline glass plate.

[0015] Furthermore, after the step of obtaining desulfurized glass liquid and sulfur-containing flue gas, the method further comprises: capturing and recovering the sulfur-containing flue gas.

[0016] Furthermore, the capture and recovery treatment method is to use ammonia water segmented spraying to treat the sulfur-containing flue gas to obtain a crude ammonium sulfate product.

[0017] Furthermore, the ammonia water segmented spraying treatment includes a front-stage spraying treatment of dilute ammonia water and a rear-stage spraying treatment of concentrated ammonia water; the concentration of the dilute ammonia water is 5-10%; the concentration of the concentrated ammonia water is 15-25%.

[0018] Compared with the prior art, the present invention has at least the following advantages:

[0019] The method for treating phosphogypsum provided by the present invention comprises preparing ingredients including phosphogypsum, quartz sand, soda ash, sodium fluorosilicate, and feldspar in a certain mass ratio, and subjecting the ingredients to a melting treatment at 1400-1600°C to obtain desulfurized glass liquid and sulfur-containing flue gas; and then obtaining a microcrystalline glass plate. This method eliminates the need for pre-treating the phosphogypsum in conventional phosphogypsum treatment processes, resulting in a simple process flow; and efficiently and safely utilizes phosphogypsum. After each ton of phosphogypsum is treated by this method, up to 1.875 tons of microcrystalline glass plates can be obtained. The resulting microcrystalline glass plates have a bending strength of up to 89 MPa, and can be widely used in architectural decoration, such as exterior wall decoration, kitchen countertops, and the like. This method promotes the process of turning phosphogypsum into "treasure from waste," and phosphogypsum can be used as a raw material without pre-treatment, thereby reducing the negative impact of phosphogypsum on the environment and making a positive contribution to the efficient resource utilization of phosphogypsum. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0021] Figure 1This is a physical picture of the glass-ceramic plate in Example 1 of the present invention;

[0022] Figure 2 This is a physical picture of the glass-ceramic plate in Example 2 of the present invention;

[0023] Figure 3 This is a physical picture of the glass-ceramic plate in Example 3 of the present invention;

[0024] Figure 4 This is a physical picture of the glass plate in Comparative Example 1 of the present invention;

[0025] Figure 5 This is a physical picture of the glass plate in Comparative Example 2 of the present invention.

[0026] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0030] In order to solve the problems of high leakage risk and complicated process flow in the prior art of recycling and treating phosphogypsum, the present invention provides a method for treating phosphogypsum, comprising the steps of:

[0031] Provide ingredients; by mass percentage, the ingredients include: 40-50% phosphogypsum, 20-30% quartz sand, 6-10% soda ash, 6-10% sodium fluorosilicate, and 10-15% feldspar. Specifically, 40-50% phosphogypsum can be converted into 15-20% calcium oxide during the melting process, which can be used as the main raw material for preparing microcrystalline glass sheets. In addition, phosphogypsum also contains silicon and potassium, which can react with other ingredients in the ingredients to form a stable wollastonite crystal structure and effectively fix trace amounts of heavy metal pollutants.

[0032] The components of the batch are mixed and melted to obtain desulfurized glass liquid and sulfur-containing flue gas; the melting temperature is 1400-1600°C. Specifically, when the melting temperature is 1400-1600°C, the reactions occurring during the batch melting process include but are not limited to:

[0033] CaSO4=CaO+SO3

[0034] Na2CO3=Na2O+CO2

[0035] Na2O+SiO2=Na2SiO3

[0036] CaO+SiO2=CaSO3

[0037] The desulfurized glass liquid is subjected to cooling treatment, forming treatment and micro-crystallization treatment in sequence to obtain a micro-crystal glass plate.

[0038] The present invention provides a method for treating phosphogypsum. The method comprises mixing ingredients including phosphogypsum, quartz sand, soda ash, sodium fluorosilicate, and feldspar in a certain mass ratio, and then melting the ingredients at 1400-1600°C to obtain desulfurized glass liquid and sulfur-containing flue gas; thereby, obtaining microcrystalline glass sheets. This method eliminates the conventional pretreatment of phosphogypsum in phosphogypsum treatment processes, resulting in a simple process flow. Furthermore, phosphogypsum is efficiently utilized, with up to 1.875 tons of microcrystalline glass sheets produced per ton of phosphogypsum treated by this method. These microcrystalline glass sheets can be widely used in architectural decoration, such as exterior wall decoration and kitchen countertops. This method promotes the process of turning phosphogypsum into "treasure" and contributes positively to the efficient resource utilization of phosphogypsum.

[0039] Furthermore, the ingredients also include additives; the additives include antimony powder and sodium nitrate; the additives account for 1 to 5% of the ingredients.

[0040] Furthermore, the melting process lasts for 480 to 500 minutes. Experiments have shown that the optimal melting process duration is between 480 and 500 minutes. If the melting process duration is less than 480 minutes, the glass liquid (batch) is prone to uneven composition and the occurrence of porosity. If the melting process duration is longer than 500 minutes, energy consumption increases, and some substances in the batch volatilize more, which is not conducive to composition stability and affects the properties of the microcrystalline glass plate.

[0041] Furthermore, the cooling treatment method is to slowly cool the desulfurized glass liquid to 1050-1150°C to obtain a cooled liquid. During the experiment, it was found that if the final temperature of the slow cooling is too high or too low, it will affect the quality of the subsequent rolled plate.

[0042] Furthermore, the forming process is to use a calender to roll the cooled liquid into a plate. Specifically, when rolling the plate, cooling water needs to flow through the upper and lower rollers of the calender; the gap between the upper and lower rollers can be adjusted according to the thickness of the required plate.

[0043] Furthermore, the cooling rate of the cooling step is 3-5°C / min.

[0044] Furthermore, the microcrystallization treatment method is to heat treat the plate obtained by the molding treatment at 500-850° C. and cool it to room temperature to obtain a microcrystalline glass plate.

[0045] Furthermore, after the step of obtaining desulfurized glass liquid and sulfur-containing flue gas, the method further includes: capturing and recovering the sulfur-containing flue gas.

[0046] Furthermore, the capture and recovery treatment method is to use ammonia water spraying to treat the sulfur-containing flue gas in sections to obtain the crude ammonium sulfate product. Specifically, if only one section of ammonia water spraying is used, the excess ammonia gas will not react completely and will escape to form secondary pollution, produce a pungent odor, and may generate PM. 2.5 Precursor.

[0047] Furthermore, the staged ammonia spraying process includes a front-end spraying process with dilute ammonia and a back-end spraying process with concentrated ammonia; the concentration of the dilute ammonia is 5-10%; the concentration of the concentrated ammonia is 15-25%. Specifically, the front-end spraying process with dilute ammonia primarily absorbs highly acidic gases (such as HF and SiF4) in the sulfur-containing flue gas; the acidic components in the back-end gas are reduced, and the back-end spraying process with concentrated ammonia recovers SO2 and CO2, reduces the volatilization of free ammonia, and further reduces ammonia escape, thereby producing a crude ammonium sulfate product.

[0048] The following are specific examples of the present invention:

[0049] Example 1

[0050] A method for processing phosphogypsum, comprising the following steps:

[0051] (1) Provide ingredients and additives; in terms of mass percentage, the components are: phosphogypsum 40%, quartz sand 30%, soda ash 7%, sodium fluorosilicate 8%, feldspar 10%, additives 5% (antimony powder 1%, sodium nitrate 4%), totaling 2 tons.

[0052] (2) The components of the above composition are mixed and then put into a glass furnace in batches for melting to obtain desulfurized glass liquid and sulfur-containing flue gas; in this embodiment, the melting temperature is 1500° C. and the melting time is 480 min.

[0053] (3) The desulfurized glass liquid is slowly cooled to 1150°C at a rate of 3°C / min and then rolled into a plate using a calender. The plate is then sent to a heat treatment furnace (850°C) for microcrystallization treatment. After cooling to room temperature, a microcrystalline glass plate is obtained. The total mass of the microcrystalline glass plate is 1.5 tons.

[0054] In this embodiment, the actual picture of the glass-ceramic plate is shown in FIG. Figure 1 , it can be seen that the surface of the glass-ceramic plate is smooth and almost flawless. Performance testing of the glass-ceramic plate shows that its bending strength reaches 86MPa, far exceeding the national building material standard of 30MPa.

[0055] (4) The generated sulfur-containing flue gas is passed into a desulfurization device containing two-stage spray components, 5% dilute ammonia water is added to the front-stage spray component; 15% concentrated ammonia water is added to the rear-stage spray component; and crude ammonium sulfate product can be obtained.

[0056] Example 2

[0057] A method for processing phosphogypsum, comprising the following steps:

[0058] (1) Provide ingredients and additives; in terms of mass percentage, the components are: phosphogypsum 50%, quartz sand 20%, soda ash 7%, sodium fluorosilicate 7%, feldspar 13%, additives 3% (antimony powder 0.5%, sodium nitrate 2.5%), totaling 2 tons.

[0059] (2) The components of the above composition are mixed and then put into a glass furnace in batches for melting to obtain desulfurized glass liquid and sulfur-containing flue gas; in this embodiment, the melting temperature is 1500° C. and the melting time is 500 min.

[0060] (3) The desulfurized glass liquid is slowly cooled to 1100°C at a rate of 5°C / min and then rolled into a plate using a calender. The plate is then sent to a heat treatment furnace (700°C) for microcrystallization treatment. After cooling to room temperature, a microcrystalline glass plate is obtained. The total mass of the microcrystalline glass plate is 1.4 tons.

[0061] In this embodiment, the actual picture of the glass-ceramic plate is shown in FIG. Figure 2 , it can be seen that the surface of the glass-ceramic plate is smooth and almost flawless. Performance testing of the glass-ceramic plate shows that its bending strength reaches 80MPa, far exceeding the national building material standard of 30MPa.

[0062] (4) The generated sulfur-containing flue gas is passed into a desulfurization device containing two-stage spray components, 5% dilute ammonia water is added to the front-stage spray component; 15% concentrated ammonia water is added to the rear-stage spray component; and crude ammonium sulfate product can be obtained.

[0063] Example 3

[0064] A method for processing phosphogypsum, comprising the following steps:

[0065] (1) Provide ingredients and additives; in terms of mass percentage, the components are: phosphogypsum 50%, quartz sand 20%, soda ash 6%, sodium fluorosilicate 6%, feldspar 14%, additives 4% (antimony powder 0.8%, sodium nitrate 3.2%), totaling 2 tons.

[0066] (2) The components of the above composition are mixed and then put into a glass furnace in batches for melting to obtain desulfurized glass liquid and sulfur-containing flue gas; in this embodiment, the melting temperature is 1530° C. and the melting time is 490 min.

[0067] (3) The desulfurized glass liquid was slowly cooled to 1130°C at a rate of 3°C / min and then rolled into a plate using a calender. The plate was then sent to a heat treatment furnace (800°C) for microcrystallization treatment. After cooling to room temperature, a microcrystalline glass plate was obtained. The total mass of the microcrystalline glass plate was 1.35 tons.

[0068] In this embodiment, the actual picture of the glass-ceramic plate is shown in FIG. Figure 3 , it can be seen that the surface of the glass-ceramic plate is smooth and almost flawless. Performance testing of the glass-ceramic plate shows that its bending strength reaches 89MPa, far exceeding the national building material standard of 30MPa.

[0069] (4) The generated sulfur-containing flue gas is passed into a desulfurization device containing two-stage spray components, 5% dilute ammonia water is added to the front-stage spray component; 15% concentrated ammonia water is added to the rear-stage spray component; and crude ammonium sulfate product can be obtained.

[0070] Comparative Example 1

[0071] Compared to Example 1, only the ingredients and additives were changed; the remaining steps remained the same. Specifically, ingredients and additives were provided; by weight, the ingredients were: 60% phosphogypsum, 10% quartz sand, 7% soda ash, 8% sodium fluorosilicate, 10% feldspar, and 5% additives (1% antimony powder, 4% sodium nitrate), totaling 2 tons.

[0072] A product glass plate was obtained, the total mass of which was 1.2 tons.

[0073] See the actual picture of the glass plate for Figure 4 , it can be seen that: the glass plate is Figure 1 , there are obvious impurities such as spots and patterns. The performance test of the microcrystalline glass plate shows that the bending strength of the microcrystalline glass plate reaches 36MPa, which is slightly higher than the national building material standard of 30MPa.

[0074] The generated sulfur-containing flue gas is passed into a desulfurization device containing two-stage spray components. 5% dilute ammonia water is added to the front spray component; 15% concentrated ammonia water is added to the rear spray component; a small amount of crude ammonium sulfate product can be obtained.

[0075] Comparative Example 2

[0076] Compared with Example 1, only the melting temperature was changed, and the other steps were the same, that is, the melting temperature was 1300°C.

[0077] A product glass plate was obtained, the total mass of which was 1.5 tons.

[0078] See the actual picture of the glass plate for Figure 5 , it can be seen that: the glass plate is Figure 1 The performance test of the glass-ceramic plate showed that its bending strength reached 44MPa, slightly higher than the national building material standard of 30MPa.

[0079] The generated sulfur-containing flue gas is passed into a desulfurization device containing two-stage spray components. 5% dilute ammonia water is added to the front spray component; 15% concentrated ammonia water is added to the rear spray component; a small amount of crude ammonium sulfate product can be obtained.

[0080] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention specification under the technical concept of the present invention, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for treating phosphogypsum, characterized in that: Including steps: Provide ingredients; The ingredients include, by mass percentage, 40-50% phosphogypsum, 20-30% quartz sand, 6-10% soda ash, 6-10% sodium fluorosilicate, and 10-15% feldspar; The components in the batch are mixed and melted to obtain desulfurized glass liquid and sulfur-containing flue gas; the melting temperature is 1400-1600° C.; The desulfurized glass liquid is subjected to cooling treatment, forming treatment and microcrystallization treatment in sequence to obtain a microcrystalline glass plate.

2. The method for treating phosphogypsum according to claim 1, wherein: The batching components also include additives; the additives include antimony powder and sodium nitrate; The additive accounts for 1 to 5% of the ingredients.

3. The method for treating phosphogypsum according to claim 1, wherein: The melting treatment takes 480 to 500 minutes.

4. The method for treating phosphogypsum according to claim 1, wherein: The cooling treatment method is to slowly cool the desulfurized glass liquid to 1050-1150° C. to obtain a cooled liquid.

5. The method for treating phosphogypsum according to claim 4, characterized in that: The forming process is to use a calender to roll the cooled liquid into a plate.

6. The method for treating phosphogypsum according to claim 4, characterized in that: The slow cooling rate in the slow cooling step is 3-5°C / min.

7. The method for treating phosphogypsum according to claim 1, characterized in that: The microcrystallization treatment is performed by heat treating the plate obtained by the molding treatment at 500-850° C. and cooling it to room temperature to obtain the microcrystalline glass plate.

8. The method for treating phosphogypsum according to claim 1, wherein: After the step of obtaining desulfurized glass liquid and sulfur-containing flue gas, the method further includes: capturing and recovering the sulfur-containing flue gas.

9. The method for treating phosphogypsum according to claim 8, characterized in that: The capture and recovery treatment method is to use ammonia water to spray the sulfur-containing flue gas in sections to obtain a crude ammonium sulfate product.

10. The method for treating phosphogypsum according to claim 9, characterized in that: The ammonia water segmented spraying treatment includes a dilute ammonia water front-stage spraying treatment and a concentrated ammonia water rear-stage spraying treatment; The concentration of the dilute ammonia water is 5-10%; the concentration of the concentrated ammonia water is 15-25%.

Images