Comprehensive treatment method of ardealite coupling industrial waste gas

Abstract

The invention belongs to the technical field of environmental protection, and particularly relates to a comprehensive treatment method of ardealite coupling industrial waste gas. The method comprises the following steps: uniformly mixing ardealite and an NH4Cl solution, oscillating and extracting, and filtering to obtain calcium-rich filtrate and ardealite residues; mixing the calcium-rich filtrate with ammonia water, introducing industrial waste gas under a stirring condition, reacting, and performing solid-liquid separation to obtain supernate and a filter cake; evaporating and crystallizing the supernate to obtain ammonium sulfate, and drying the filter cake to obtain the submicron calcium carbonate. By adopting the method, the joint resourceful treatment of the ardealite and the industrial waste gas is realized, meanwhile, the high-value product ammonium sulfate is prepared, the submicron calcium carbonate is prepared under the condition that a crystal form control agent is not added, and important reference is provided for widening the ardealite resourceful path and reducing the emission of actual industrial waste gas CO2.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and more specifically relates to a comprehensive treatment method for phosphogypsum coupled industrial waste gas. Background Art

[0002] Phosphogypsum is an industrial solid waste produced by the wet process of phosphoric acid production. Its main component is CaSO4·2H2O, and it also contains impurities such as inorganic acids, phosphorus, fluorine, organic matter, heavy metal elements and radionuclides. Large stocks of phosphogypsum with high impurity content not only occupy a large amount of land resources, but also seriously pollute the environment. At present, important resource utilization methods of phosphogypsum include cement retarders, road filling, cementitious materials, gypsum boards, building gypsum, sulfuric acid preparation, etc. The impurities in phosphogypsum lead to poor performance and low value of resource products. In addition, due to the long-distance transportation cost consumption and the prejudice against "industrial solid waste", it is impossible to compete with similar products in the market. In summary, it is urgent to explore new ways to utilize phosphogypsum resources.

[0003] Environmental problems caused by greenhouse gas CO2 have become a global issue. Industries such as coal, steel, nonferrous metals, building materials and chemicals are industrial sources of excessive CO2 emissions. The CO2 content of waste gas emitted by these industries usually fluctuates around 15%. Seeking new methods to solve industrial waste gas CO2 is the key to addressing climate change and carbon emission reduction.

[0004] How to provide a comprehensive treatment method for phosphogypsum and industrial waste gas, synergistically solve the problems of phosphogypsum and CO2, and broaden the resource utilization path of phosphogypsum and industrial waste gas has become an urgent problem that technicians in this field need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a comprehensive treatment method for phosphogypsum coupled with industrial waste gas, so as to solve the problems existing in the above-mentioned prior art and realize the joint resource treatment of phosphogypsum and industrial waste gas.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a comprehensive treatment method for phosphogypsum coupled industrial waste gas, the steps comprising:

[0008] After the phosphogypsum and NH4Cl solution are evenly mixed, the mixture is extracted by oscillation, and filtered to obtain a calcium-rich filtrate and phosphogypsum residue;

[0009] The calcium-rich filtrate is mixed with aqueous ammonia, and industrial waste gas is introduced under stirring conditions. After the reaction, solid-liquid separation is performed to obtain a supernatant and a filter cake;

[0010] The supernatant is evaporated and crystallized to obtain ammonium sulfate, and the filter cake is dried to obtain submicron calcium carbonate.

[0011] Furthermore, the liquid-to-solid ratio of the NH4Cl solution and phosphogypsum is 50-80 mL / g.

[0012] Furthermore, the concentration of the NH4Cl solution is 2-3 mol / L.

[0013] Furthermore, the oscillation extraction time is 10 to 60 minutes.

[0014] Furthermore, the filtration uses a glass fiber filter membrane of 0.45 to 1.0 μm.

[0015] Optionally, the filtration uses a 0.45 μm, 0.8 μm or 1.0 μm glass fiber filter membrane.

[0016] Furthermore, the volume ratio of the calcium-rich filtrate to aqueous ammonia is 15:3-15.

[0017] Optionally, the volume ratio of the calcium-rich filtrate to aqueous ammonia is 15:3, 15:4, 15:5 or 15:15.

[0018] Furthermore, the concentration of the ammonia water is 2.5wt.%.

[0019] Furthermore, after the calcium-rich filtrate and the ammonia water are mixed, the step of adjusting the pH value of the mixed solution of the calcium-rich filtrate and the ammonia water to 8.6-9.3 is also included.

[0020] Furthermore, the stirring rate is 1000-2000 rpm.

[0021] Furthermore, the rate of introducing industrial waste gas is 60 to 200 mL / min.

[0022] Furthermore, the reaction time is 21 to 30 minutes.

[0023] Furthermore, the solid-liquid separation is performed using a 0.01-0.1 μm polyethersulfone filter membrane.

[0024] Furthermore, the temperature of the evaporation crystallization is 105-120°C.

[0025] Furthermore, the temperature of the drying treatment is 40-80°C.

[0026] The industrial waste gas used in the above scheme contains carbon dioxide gas, wherein the carbon dioxide content is not less than 10% (volume fraction), generally 15% (volume fraction).

[0027] The second technical solution of the present invention is to provide a method for preparing submicron calcium carbonate without adding a crystal form control agent, the steps comprising:

[0028] After the phosphogypsum and NH4Cl solution are evenly mixed, the mixture is extracted by oscillation, and filtered to obtain a calcium-rich filtrate and phosphogypsum residue;

[0029] The calcium-rich filtrate is mixed with aqueous ammonia, and industrial waste gas is introduced under stirring conditions. After the reaction, solid-liquid separation is performed to obtain a solid product;

[0030] The solid product is dried to obtain submicron calcium carbonate.

[0031] Furthermore, the liquid-to-solid ratio of the NH4Cl solution and phosphogypsum is 50-80 mL / g.

[0032] Furthermore, the concentration of the NH4Cl solution is 2-3 mol / L.

[0033] Furthermore, the oscillation extraction time is 10 to 60 minutes.

[0034] Furthermore, the filtration uses a glass fiber filter membrane of 0.45 to 1.0 μm.

[0035] Optionally, the filtration uses a 0.45 μm, 0.8 μm or 1.0 μm glass fiber filter membrane.

[0036] Furthermore, the volume ratio of the calcium-rich filtrate to aqueous ammonia is 15:3-15.

[0037] Optionally, the volume ratio of the calcium-rich filtrate to aqueous ammonia is 15:3, 15:4, 15:5 or 15:15.

[0038] Furthermore, the concentration of the ammonia water is 2.5wt.%.

[0039] Furthermore, after the calcium-rich filtrate and the ammonia water are mixed, the step of adjusting the pH value of the mixed solution of the calcium-rich filtrate and the ammonia water to 8.6-9.3 is also included.

[0040] Furthermore, the stirring rate is 1000-2000 rpm.

[0041] Furthermore, the rate of introducing industrial waste gas is 60 to 200 mL / min.

[0042] Furthermore, the reaction time is 21 to 30 minutes.

[0043] Furthermore, the solid-liquid separation is performed using a 0.01-0.1 μm polyethersulfone filter membrane.

[0044] Furthermore, the temperature of the drying treatment is 40-80°C.

[0045] The industrial waste gas used in the above scheme has a carbon dioxide content of not less than 10% (volume fraction), generally 15% (volume fraction).

[0046] In the prior art, when preparing submicron calcium carbonate, a crystal form control agent is generally added to control the particle size of the calcium carbonate product. The method of the present invention achieves high-efficiency calcium ion dissolution of phosphogypsum by optimizing parameters, separates impurities that are difficult to tolerate in phosphogypsum, and regulates key carbon fixation parameters such as pH and stirring rate, CO2 flow rate, reaction time, etc. Under mild conditions of room temperature and normal pressure, and without adding a crystal form control agent, phosphogypsum fixes CO2 in industrial waste gas to prepare submicron calcium carbonate. This process is mild, simple, and low-cost, and is of great reference significance for the actual disposal of phosphogypsum and industrial waste gas CO2. The prepared submicron calcium carbonate can be used in papermaking, rubber, plastics, paints and coatings, toothpaste, feed and other industries.

[0047] The present invention discloses the following technical effects:

[0048] The present invention is based on the synergistic solution to the problem of phosphogypsum and industrial waste gas, and utilizes the rich Ca in phosphogypsum to 2+ It reacts with CO2 in industrial waste gas in an alkaline medium to generate calcium carbonate minerals with a wide range of applications and produces high-value sulfate products as a by-product, providing an important reference and lesson for broadening the resource utilization path of phosphogypsum and reducing CO2 emissions from actual industrial waste gas.

[0049] The present invention provides a process for capturing industrial waste gas by phosphogypsum based on the principle of "chemical extraction-factor control-induced nucleation-rapid crystallization". While efficiently recycling the calcium ions in the phosphogypsum, a large amount of CO2 in industrial waste gas can be simultaneously fixed, and the final product has a high economic value. The process is simple and feasible, the reaction is rapid, and the cost is low.

[0050] The present invention carries out the reaction at normal temperature and pressure, and a high-purity valuable product can be obtained by adding less raw materials, and submicron calcium carbonate is prepared without adding a crystal form control agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0052] Figure 1 It is a process flow diagram of a specific embodiment of the present invention;

[0053] Figure 2 is the XRD pattern of the evaporation crystallization product in step S3;

[0054] Figure 3is the XRD pattern of the filter cake dried product in step S4;

[0055] Figure 4 TG thermogravimetric analysis of the filter cake drying product calcium carbonate in step S4;

[0056] Figure 5 is a SEM image of calcium carbonate, a filter cake drying product in step S4;

[0057] Figure 6 This is the SEM image of sodium carbonate obtained in Comparative Example 2. DETAILED DESCRIPTION

[0058] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0059] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0060] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0061] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0062] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0063] In the process of preparing calcium carbonate from phosphogypsum, a crystal form controller (also called a crystal growth regulator or crystal habit modifier) ​​is generally added to affect the physical properties of the final product, such as particle size, shape, and crystallinity, thereby improving the quality of the product and meeting the needs of different application fields. The selection and use of the crystal form controller depends on the specific characteristics of the required calcium carbonate.

[0064] Common crystal control agents include:

[0065] Organic acids and their salts: such as citric acid, tartaric acid, oxalic acid, etc. They can form complexes with calcium ions, thereby changing the crystallization process of calcium carbonate and affecting its morphology and particle size distribution.

[0066] Surfactants: Nonionic, anionic or cationic surfactants can be used as crystal form controllers. They adsorb on the surface of the calcium carbonate particles being formed to change their growth direction and thus regulate the crystal structure.

[0067] Polymers: Water-soluble polymer materials such as polyacrylic acid and polyvinyl alcohol can also effectively control the crystal shape of calcium carbonate. These substances can form a protective layer in the solution and inhibit the growth rate of specific crystal faces.

[0068] Inorganic compounds: Certain inorganic substances such as phosphates and sodium silicate are also used as crystal control agents, which affect the microstructure of the product by changing the solution environment or directly participating in the reaction.

[0069] Usually, the crystal form control agent is added to the reaction system before the reaction starts.

[0070] The specific type and amount of the crystal form control agent need to be adjusted according to the requirements of the target product. Sometimes several different types of crystal form control agents may be needed to be used in combination to obtain the ideal performance.

[0071] Calcium carbonate is a very important inorganic non-metallic material and industrial raw material, which can be widely used in papermaking, civil engineering, plastics, coatings, inks, sealants, adhesives, cosmetics, rubber products, biological preservation, dyeing and chemical, drug carrier materials and other fields. In addition, ammonium sulfate can be used to make agricultural fertilizers, refractory materials, food catalysts, dyeing agents, batteries, etc., and sodium sulfate can be used in detergent fillers, cooking agents, non-ferrous metallurgy, leather and other fields. Using phosphogypsum to fix mineralized CO2 can solve the waste problem while achieving economic income and promoting the implementation of this process.

[0072] The technical solutions shown in the embodiments of the present invention are all carried out at room temperature (23±2° C.) and normal pressure (101.325 kPa).

[0073] The raw materials and reagents used in the specific implementation scheme of the present invention are all commercially available products, among which phosphogypsum is provided by Guizhou Shengwei Kaiyang Chemical Co., Ltd., and the main CaSO4·2H2O content is about 94wt.%; the industrial waste gas is the waste gas discharged from the thermal power plant, and the carbon dioxide content is about 15% (volume fraction).

[0074] Figure 1 It is a schematic diagram of the process flow of a specific implementation scheme of the present invention.

[0075] Example 1

[0076] A comprehensive treatment method for phosphogypsum coupled industrial waste gas, comprising the following steps:

[0077] S1. Mix phosphogypsum and 2 mol / L NH4Cl solution in a ratio of 1 g: 60 mL, extract by oscillation for 20 min, and filter using a 0.45 μm glass fiber filter to obtain a calcium-rich filtrate and phosphogypsum residue;

[0078] S2, the calcium-rich filtrate obtained in step S1 and ammonia water (concentration of 2.5%) were mixed in a volume ratio of 15:4, diluted with water to a pH of 8.73, and then the stirring rate was controlled to 2000rpm, industrial waste gas (carbon dioxide content of about 15%) was introduced, and the ventilation rate was 100mL / min. After reacting for 30min, the mixture was filtered through a 0.02μm polyethersulfone filter membrane to obtain a supernatant and a filter cake; wherein the tail gas after the reaction was collected by an absorption tower and reused;

[0079] S3, transferring the supernatant in step S2 to a ceramic evaporating dish, evaporating at 120° C. until crystals are precipitated and drying to obtain ammonium sulfate;

[0080] S4. Bake the filter cake in step S2 in an oven at 40° C. until completely dry to obtain submicron sodium carbonate.

[0081] The evaporation crystallization product in step S3 is subjected to XRD analysis and detection, and the result is as follows: Figure 2 shown.

[0082] Figure 2 This is the XRD diagram of the evaporation crystallization product in step S3. It can be seen from the figure that the crystallization product is high-purity ammonium sulfate.

[0083] The cake dried product in step S4 was characterized by XRD, TG and SEM. Figures 3 to 5 shown.

[0084] Figure 3 is the XRD diagram of the filter cake drying product in step S4; it can be seen from the figure that the filter cake drying product is pure phase calcite type calcium carbonate.

[0085] Figure 4This is the TG thermogravimetric analysis of the calcium carbonate product of the filter cake drying in step S4; as can be seen from the figure, the purity calculated by thermogravimetric analysis is 98.1%.

[0086] Figure 5 This is a SEM image of the filter cake drying product calcium carbonate in step S4; as can be seen from the figure, the filter cake drying product calcium carbonate is a submicron mineral with a particle size between 200 and 300 nm, indicating that the present invention scheme has prepared submicron calcium carbonate without adding a crystal form control agent.

[0087] The calcium ion content of the phosphogypsum in step S1 of Example 1 was determined by X-ray fluorescence spectrometry (XRF), and the calcium ion concentration in the calcium-rich filtrate was determined by flame atomic absorption spectrometry. The results are shown in Table 1. It can be seen that after the treatment in step S1, the Ca in the phosphogypsum can be reduced to 0. 2+ Almost 100% leaching.

[0088] Table 1

[0089]

[0090] Example 2

[0091] A comprehensive treatment method for phosphogypsum coupled industrial waste gas, comprising the following steps:

[0092] S1. Mix phosphogypsum and 3 mol / L NH4Cl solution in a ratio of 1 g: 50 mL, extract by oscillation for 30 min, and filter using a 0.8 μm glass fiber filter to obtain a calcium-rich filtrate and phosphogypsum residue;

[0093] S2, the calcium-rich filtrate obtained in step S1 and ammonia water (concentration of 2.5%) were mixed in a volume ratio of 15:5, diluted with water to a pH of 9.0, and then the stirring rate was controlled to 1000rpm, industrial waste gas (carbon dioxide content of about 15%) was introduced, and the ventilation rate was 200mL / min. After reacting for 21min, the mixture was filtered through a 0.1μm polyethersulfone filter membrane to obtain a supernatant and a filter cake; wherein the tail gas after the reaction was collected by an absorption tower and reused;

[0094] S3, transferring the supernatant in step S2 to a ceramic evaporating dish, evaporating at 105° C. until crystals are precipitated and drying to obtain ammonium sulfate;

[0095] S4, baking the filter cake in step S2 in an oven at 80° C. until completely dry to obtain submicron sodium carbonate.

[0096] Example 3

[0097] A comprehensive treatment method for phosphogypsum coupled industrial waste gas, comprising the following steps:

[0098] S1. Mix phosphogypsum and 2 mol / L NH4Cl solution in a ratio of 1 g: 80 mL, extract by oscillation for 60 min, and filter using a 1.0 μm glass fiber filter to obtain a calcium-rich filtrate and phosphogypsum residue;

[0099] S2, the calcium-rich filtrate obtained in step S1 and ammonia water (concentration of 2.5%) were mixed in a volume ratio of 15:15, diluted with water to a pH of 9.3, and then the stirring rate was controlled to 2000rpm, industrial waste gas (carbon dioxide content of about 15%) was introduced, and the ventilation rate was 60mL / min. After reacting for 25min, the mixture was filtered through a 0.01μm polyethersulfone filter membrane to obtain a supernatant and a filter cake; wherein the tail gas after the reaction was collected by an absorption tower and reused;

[0100] S3, transferring the supernatant in step S2 to a ceramic evaporating dish, evaporating at 120° C. until crystals are precipitated and drying to obtain ammonium sulfate;

[0101] S4. Bake the filter cake in step S2 in an oven at 40° C. until completely dry to obtain submicron sodium carbonate.

[0102] Comparative Example 1

[0103] A comprehensive treatment method for phosphogypsum coupled industrial waste gas, comprising the following steps:

[0104] S1. Mix phosphogypsum and 2 mol / L NaOH solution in a ratio of 1 g: 60 mL, shake and extract for 20 min, and filter using a 0.45 μm glass fiber filter to obtain a calcium-rich filtrate and phosphogypsum residue; the calcium-rich filtrate was tested using the same detection method as in Example 1, and it was found that the calcium ion leaching rate was less than 90% (and the calcium ions would bind to OH - Affects the separation process of insoluble impurities in phosphogypsum, and thus affects the purity of the subsequent carbon fixation product calcium carbonate);

[0105] S2, the calcium-rich filtrate obtained in step S1 and ammonia water (concentration of 2.5%) were mixed in a volume ratio of 15:4, diluted with water to a pH of 8.73, and then the stirring rate was controlled to 2000rpm, industrial waste gas (carbon dioxide content of about 15%) was introduced, and the ventilation rate was 100mL / min. After reacting for 30min, the mixture was filtered through a 0.02μm polyethersulfone filter membrane to obtain a supernatant and a filter cake; wherein the tail gas after the reaction was collected by an absorption tower and reused;

[0106] S3, transferring the supernatant in step S2 to a ceramic evaporating dish, evaporating at 120° C. until crystals are precipitated and drying to obtain ammonium sulfate;

[0107] S4. The filter cake in step S2 is baked in an oven at 40° C. until completely dry to obtain sodium carbonate. After testing, the purity of the obtained sodium carbonate is less than 90%.

[0108] Comparative Example 2

[0109] A comprehensive treatment method for phosphogypsum coupled industrial waste gas, comprising the following steps:

[0110] S1. Phosphogypsum and 2 mol / L NaOH solution were mixed in a ratio of 1 g: 60 mL, and the mixture was shaken and extracted for 20 min. The mixture was filtered using a 0.45 μm glass fiber filter membrane to obtain a calcium-rich filtrate and a phosphogypsum residue. The calcium-rich filtrate was tested using the same detection method as in Example 1. It was found that the calcium ion leaching rate was less than 90% (and the OH - Will bind Ca 2+ The generated Ca(OH)2 filter residue has a negative impact on the subsequent filtration and separation of insoluble impurities in phosphogypsum; if forced separation is performed, the insoluble impurities and some calcium ions will be separated simultaneously, resulting in calcium loss).

[0111] S2, the calcium-rich filtrate obtained in step S1 and ammonia water (concentration of 2.5%) were mixed in a volume ratio of 15:4, and polyvinyl pyrrolidone (the mass / volume ratio of the crystal form control agent to the calcium-rich filtrate was 0.03 g: 30 mL) was added, and the pH was diluted with water to 8.73, and then the stirring rate was controlled to 2000 rpm, and industrial waste gas (carbon dioxide content was about 15%) was introduced at a ventilation rate of 100 mL / min. After reacting for 30 minutes, the mixture was filtered through a 0.02 μm polyethersulfone filter membrane to obtain a supernatant and a filter cake; wherein the tail gas after the reaction was collected by an absorption tower and reused;

[0112] S3, transferring the supernatant in step S2 to a ceramic evaporating dish, evaporating at 120° C. until crystals are precipitated and drying to obtain ammonium sulfate;

[0113] S4, baking the filter cake in step S2 in an oven at 40°C until completely dry to obtain sodium carbonate. After testing, the particle size of the obtained sodium carbonate is submicron, but too much crystal form control agent is attached to the surface, and the purity is less than 90%. Figure 6 As shown, it can be seen that the crystal form control agent will adhere to the surface of the product and is difficult to remove later, resulting in a product purity of <90%, which is difficult to meet the usage standard.

[0114] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0115] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A comprehensive treatment method for phosphogypsum coupled industrial waste gas, characterized in that the steps include: After the phosphogypsum and NH4Cl solution are evenly mixed, the mixture is extracted by oscillation, and filtered to obtain a calcium-rich filtrate and phosphogypsum residue; The calcium-rich filtrate is mixed with aqueous ammonia, and industrial waste gas is introduced under stirring conditions. After the reaction, solid-liquid separation is performed to obtain a supernatant and a filter cake; The supernatant is evaporated and crystallized to obtain ammonium sulfate, and the filter cake is dried to obtain submicron calcium carbonate.

2. The comprehensive treatment method according to claim 1, characterized in that: The liquid-to-solid ratio of the NH4Cl solution to phosphogypsum is 50-80 mL / g; and / or, The concentration of the NH4Cl solution is 2-3 mol / L; and / or, The oscillation extraction time is 10 to 60 minutes; and / or, The industrial waste gas is industrial waste gas containing carbon dioxide.

3. The comprehensive treatment method according to claim 1, characterized in that: The volume ratio of the calcium-rich filtrate to aqueous ammonia is 15:3-15; and / or, The concentration of the ammonia water is 2.5 wt.%.

4. The comprehensive treatment method according to claim 1, characterized in that: After the calcium-rich filtrate and the ammonia water are mixed, the method further comprises the step of adjusting the pH value of the mixed solution of the calcium-rich filtrate and the ammonia water to 8.6-9.

3.

5. The comprehensive treatment method according to claim 1, characterized in that: The stirring rate is 1000-2000 rpm; and / or, The rate of introducing industrial waste gas is 60 to 200 mL / min; and / or, The reaction time is 21 to 30 minutes.

6. The comprehensive treatment method according to claim 1, characterized in that: The evaporation crystallization temperature is 105-120°C; and / or, The temperature of the drying process is 40-80°C.

7. A method for preparing submicron calcium carbonate without adding a crystal form control agent, characterized in that the steps include: After the phosphogypsum and NH4Cl solution are evenly mixed, the mixture is extracted by oscillation, and filtered to obtain a calcium-rich filtrate and phosphogypsum residue; The calcium-rich filtrate is mixed with aqueous ammonia, and industrial waste gas is introduced under stirring conditions. After the reaction, solid-liquid separation is performed to obtain a solid product; The solid product is dried to obtain submicron calcium carbonate.

8. The method according to claim 7, characterized in that The liquid-to-solid ratio of the NH4Cl solution to phosphogypsum is 50-80 mL / g; and / or, The concentration of the NH4Cl solution is 2-3 mol / L; and / or, The oscillation extraction time is 10 to 60 minutes.

9. The method according to claim 7, characterized in that The volume ratio of the calcium-rich filtrate to aqueous ammonia is 15:3-15; and / or, The concentration of the aqueous ammonia is 2.5 wt.%; and / or, After the calcium-rich filtrate and ammonia water are mixed, the step of adjusting the pH value of the mixture of the calcium-rich filtrate and ammonia water to 8.6-9.3 is also included; and / or, The stirring rate is 1000-2000 rpm; and / or, The rate of introducing industrial waste gas is 60 to 200 mL / min; and / or, The reaction time is 21 to 30 minutes.

10. The method according to claim 7, characterized in that The temperature of the drying process is 40-80°C.

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