Method for improving fluorine content in plastering gypsum and plastering gypsum

Abstract

The invention relates to a method for improving fluorine content in plastering gypsum and the plastering gypsum. The method comprises the following steps: preparing raw materials; hydrolyzing the fluorine fixing agent to generate multi-core ions with high-valence positive charges; mixing the prepared fluorine-fixing agent with the raw materials of the plastering gypsum according to a ratio, so that the fluorine-fixing agent is in contact with fluorine ions and is subjected to complex reaction to form a complex; controlling the mixing time, and detecting the content change of fluorine ions in the reaction to judge whether the reaction is complete; after the reaction is completed, detecting the fluorine ion content in the plastering gypsum; and drying and crushing the plastering gypsum treated by the fluorine fixing agent to obtain the final plastering gypsum with low fluorine ion content. By accurately controlling the dosage, temperature and time of the fluorine fixing agent and monitoring the fluorine ion concentration in real time, it is ensured that the fluorine ion content in the plastering gypsum meets the safety standard, metal ion release is promoted through acidic hydrolysis, the surfactant and the ion exchange resin are added, the reaction efficiency is improved, and the method is environmentally friendly and high in adaptability.

Description

Technical Field

[0001] The invention relates to the field of building material preparation, in particular to a method for improving fluorine content in plastering gypsum and the plastering gypsum. Background Art

[0002] Plaster gypsum is a commonly used building material in the construction industry. Its excellent plasticity and durability make it one of the main materials for building surface decoration. However, gypsum clinker may contain a certain amount of fluoride ions during the preparation process, especially when fluoride-containing minerals such as phosphogypsum and fluorgypsum are used as raw materials. The fluoride ion content is likely to exceed the standard. Fluoride ions have certain hazards to the environment and human health. Therefore, its content needs to be controlled during the production process.

[0003] Currently, there are mainly the following methods for treating fluoride ions in gypsum: physical adsorption, chemical precipitation, and ion exchange. However, these methods have the problems of long processing time, high cost, or unsatisfactory effect. Especially in the large-scale production of gypsum products, how to quickly and effectively reduce the fluoride ion content without affecting the strength and other properties of the gypsum has always been a difficult problem to be solved in production. The present invention proposes a method for effectively reducing the fluoride ion content in plastering gypsum by hydrolyzing a fluoride-fixing agent and mixing it with gypsum raw materials through a complex reaction. This method has the advantages of simple operation, low cost, rapid reaction, and stable effect, and can be widely used in the production process of plastering gypsum. Summary of the Invention

[0004] The present invention aims to solve the technical problems existing in the prior art and provides a novel method for the manufacture of a novel nanostructured carbon foam.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: a method for improving the fluorine content in plastering gypsum, comprising: Prepare raw materials, including 88 parts of gypsum clinker, 6 parts of vitrified microspheres, 3 parts of heavy calcium carbonate, 0.15 parts of water retaining agent, 0.003 parts of air entraining agent, 0.1 parts of retarder, 0.3 parts of starch ether and 0.1 parts of fluorine-fixing agent; Hydrolyze the fluorine-fixing agent to generate polynuclear ions with high positive charges; The prepared fluorine-fixing agent is mixed with the raw materials of the plastering gypsum in proportion, so that the fluorine-fixing agent contacts the fluoride ions and undergoes a complex reaction to form a complex; Control the mixing time and detect the change in the fluoride ion content during the reaction to determine whether the reaction is complete; After the reaction is completed, the fluoride ion content in the plaster is tested. If the fluoride ion content does not meet the standard, the amount of fluoride-fixing agent is increased; The plastering gypsum treated with the fluorine-fixing agent is dried and crushed to obtain the final plastering gypsum with low fluoride ion content.

[0006] Preferably, the hydrolysis of the fluorine-fixing agent to generate polynuclear ions with high positive charges specifically includes: Acidic hydrolysis conditions are used to promote the release of metal ions in the fluorine-fixing agent, and chlorinated acid is used to adjust the pH value to form polynuclear ions with high positive charges; In the hydrolysis reaction, adding surfactant increases the hydrolysis rate and accelerates the release of ions; Control the temperature and time of the hydrolysis reaction of the fluorine-fixing agent, the temperature is between 50°C and 70°C, and the reaction time is controlled within 20 to 40 minutes; During the hydrolysis process, ion exchange resin is introduced to improve the adsorption and complexation effect of fluoride ions and accelerate the combination of fluoride ions with high-valent polynuclear ions in the fluoride-fixing agent; After the hydrolysis reaction is completed, the hydrolysis solution is treated by ultrafiltration technology to remove substances and impurities that have not been completely reacted during the reaction process.

[0007] Preferably, the step of mixing the prepared fluorine-fixing agent with the raw materials of the plastering gypsum in proportion, allowing the fluorine-fixing agent to contact with the fluoride ions and undergoing a complex reaction to form a complex comprises: Put the raw materials and the fluorine-fixing agent into the mixing equipment in proportion. During the mixing process, keep stirring evenly to promote the complexation reaction between the fluorine-fixing agent and fluoride ions; Maintain the reaction temperature between 20°C and 30°C, and control the initial mixing time to 5-10 minutes; Sampling was performed regularly to detect changes in the fluoride ion content, and the removal of fluoride ions during the reaction was monitored in real time.

[0008] Preferably, controlling the mixing time and detecting the change in the fluoride ion content during the reaction to determine whether the reaction is complete specifically includes: The fluoride ion content of each sample is tested, and the fluoride ion concentration in the sample liquid is monitored in real time using a fluoride ion selective electrode. The test results are recorded and a graph showing the change in fluoride ion concentration over time is drawn; The change in fluoride ion concentration is used to determine whether the reaction is nearly complete. If the fluoride ion concentration decreases to a value close to the predetermined target value, the reaction is nearly complete. When the change in the fluoride ion content during the sampling process tends to be stable and reaches the preset target concentration, the reaction is judged to be complete.

[0009] Preferably, after the reaction is completed, the fluoride ion content in the plaster is detected. If the fluoride ion content does not meet the standard, increasing the amount of the fluoride-fixing agent specifically includes: According to the difference between the current fluoride ion content and the target content, the amount of fluoride-fixing agent to be added is recalculated, and the fluoride-fixing agent is prepared according to the calculated result; Add the fluorine-fixing agent to the reaction system by weighing. After adding the fluorine-fixing agent, continue to stir and mix to ensure that the fluorine-fixing agent is completely dissolved; Continue to monitor the reaction until the fluoride ion concentration reaches the target requirement. After adding the fluoride-fixing agent and completing the mixing reaction, test the fluoride ion concentration again and compare the fluoride ion content at this time with the target value to ensure that the standard has been met.

[0010] A plastering plaster is composed of the following raw materials in parts by weight: 80-95 parts of gypsum clinker, 3-10 parts of vitrified microspheres, 0.5-10 parts of heavy calcium carbonate, 0.05-0.30 parts of water retaining agent, 0.001-0.01 parts of air entraining agent, 0.05-0.15 parts of retarder, 0.1-0.5 parts of starch ether, and 0.01-0.20 parts of fluorine-fixing agent.

[0011] Preferably, the gypsum clinker is one of phosphogypsum and fluorgypsum, the fluoride ion content in the phosphogypsum is 20-1000 mg / kg, the particle size of the heavy calcium carbonate is 200-325 mesh, the bulk density of the vitrified microspheres is 70-120 kg / cm³, and the particle size is 70-90 mesh, the fluorine-fixing agent is one of polyferric sulfate, polyaluminum chloride, aluminum oxide and calcium chloride, and the water-retaining agent is one of hydroxyethyl cellulose, hydroxyethyl methyl cellulose ether and hydroxypropyl methyl cellulose ether.

[0012] Preferably, the air-entraining agent is one of rosin resin air-entraining agent, alkyl sulfate air-entraining agent, alkylbenzene sulfonate air-entraining agent, and fatty alcohol sulfonate air-entraining agent; the retarder is one of sodium gluconate, tartaric acid, borax, lignin sulfonate, sodium carboxymethyl cellulose, phosphoric acid, and protein retarder; the starch ether is one of silicate mineral material and ether material; the fluoride ion content in the gypsum clinker is 20-1000 mg / kg, and the fluoride ion content is reduced to less than 0.02% by adding a fluoride-fixing agent.

[0013] The present invention has the following beneficial effects: by precisely controlling the amount of fluorine-fixing agent, temperature, and time, and by real-time monitoring of fluoride ion concentration, the present invention ensures that the fluoride ion content in the plastering gypsum meets safety standards. It also utilizes acidic hydrolysis to promote the release of metal ions, and by adding surfactants and ion exchange resins, it improves reaction efficiency and shortens reaction time. This method is low-cost, environmentally friendly, and highly adaptable, making it particularly suitable for phosphogypsum and fluorgypsum with high fluoride content, meeting green production requirements. Compared to traditional methods, it offers significant economic and environmental advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a step flow chart of the present invention; Figure 2This is a flow chart of the detailed steps for hydrolyzing the fluorine-fixing agent to generate polynuclear ions with high positive charges in the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0016] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "plurality" means two or more, unless otherwise specifically specified.

[0017] In the description of this application, the term "for example" is used to mean "used as an example, illustration or explanation". Any embodiment described as "for example" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is given to enable any person skilled in the art to implement and use the present invention. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art will recognize that the present invention can be implemented without using these specific details. In other examples, well-known structures and processes will not be elaborated in detail to avoid obscuring the description of the present invention with unnecessary details. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

[0018] Reference Figure 1 A method for improving the fluorine content in plastering gypsum is shown, comprising: Prepare raw materials, including 88 parts of gypsum clinker, 6 parts of vitrified microspheres, 3 parts of heavy calcium carbonate, 0.15 parts of water retaining agent, 0.003 parts of air entraining agent, 0.1 parts of retarder, 0.3 parts of starch ether and 0.1 parts of fluorine-fixing agent; Hydrolyze the fluorine-fixing agent to generate polynuclear ions with high positive charges; The prepared fluorine-fixing agent is mixed with the raw materials of the plastering gypsum in proportion, so that the fluorine-fixing agent contacts the fluoride ions and undergoes a complex reaction to form a complex; Control the mixing time and detect the change in the fluoride ion content during the reaction to determine whether the reaction is complete; After the reaction is completed, the fluoride ion content in the plaster is tested. If the fluoride ion content does not meet the standard, the amount of fluoride-fixing agent is increased; The plastering gypsum treated with the fluorine-fixing agent is dried and crushed to obtain the final plastering gypsum with low fluoride ion content.

[0019] Reference Figure 2 As shown, the hydrolysis of the fluorine-fixing agent to generate polynuclear ions with high positive charges specifically includes: Acidic hydrolysis conditions are used to promote the release of metal ions in the fluorine-fixing agent, and chlorinated acid is used to adjust the pH value to form polynuclear ions with high positive charges; In the hydrolysis reaction, adding surfactant increases the hydrolysis rate and accelerates the release of ions; Control the temperature and time of the hydrolysis reaction of the fluorine-fixing agent, the temperature is between 50°C and 70°C, and the reaction time is controlled within 20 to 40 minutes; During the hydrolysis process, ion exchange resin is introduced to improve the adsorption and complexation effect of fluoride ions and accelerate the combination of fluoride ions with high-valent polynuclear ions in the fluoride-fixing agent; After the hydrolysis reaction is completed, the hydrolysis solution is treated by ultrafiltration technology to remove substances and impurities that have not been completely reacted during the reaction process.

[0020] The prepared fluorine-fixing agent is mixed with the raw materials of the plastering gypsum in proportion, so that the fluorine-fixing agent and the fluoride ions are in contact and undergo a complex reaction to form a complex compound. Specifically, the following steps are performed: Put the raw materials and the fluorine-fixing agent into the mixing equipment in proportion. During the mixing process, keep stirring evenly to promote the complexation reaction between the fluorine-fixing agent and fluoride ions; Maintain the reaction temperature between 20°C and 30°C, and control the initial mixing time to 5-10 minutes; Sampling was performed regularly to detect changes in the fluoride ion content, and the removal of fluoride ions during the reaction was monitored in real time.

[0021] Controlling the mixing time and detecting the change in the fluoride ion content during the reaction to determine whether the reaction is complete specifically includes: The fluoride ion content of each sample is tested, and the fluoride ion concentration in the sample liquid is monitored in real time using a fluoride ion selective electrode. The test results are recorded and a graph showing the change in fluoride ion concentration over time is drawn; The change in fluoride ion concentration is used to determine whether the reaction is nearly complete. If the fluoride ion concentration decreases to a value close to the predetermined target value, the reaction is nearly complete. When the change in the fluoride ion content during the sampling process tends to be stable and reaches the preset target concentration, the reaction is judged to be complete.

[0022] After the reaction is completed, the fluoride ion content in the plaster is detected. If the fluoride ion content does not meet the standard, the amount of fluoride-fixing agent is increased, specifically including: According to the difference between the current fluoride ion content and the target content, the amount of fluoride-fixing agent to be added is recalculated, and the fluoride-fixing agent is prepared according to the calculated result; Add the fluorine-fixing agent to the reaction system by weighing. After adding the fluorine-fixing agent, continue to stir and mix to ensure that the fluorine-fixing agent is completely dissolved; Continue to monitor the reaction until the fluoride ion concentration reaches the target requirement. After adding the fluoride-fixing agent and completing the mixing reaction, test the fluoride ion concentration again and compare the fluoride ion content at this time with the target value to ensure that the standard has been met.

[0023] A plastering plaster is composed of the following raw materials in parts by weight: 80-95 parts of gypsum clinker, 3-10 parts of vitrified microspheres, 0.5-10 parts of heavy calcium carbonate, 0.05-0.30 parts of water retaining agent, 0.001-0.01 parts of air entraining agent, 0.05-0.15 parts of retarder, 0.1-0.5 parts of starch ether, and 0.01-0.20 parts of fluorine-fixing agent.

[0024] The gypsum clinker is one of phosphogypsum and fluorgypsum, the fluoride ion content in the phosphogypsum is 20-1000 mg / kg, the particle size of the heavy calcium carbonate is 200-325 mesh, the bulk density of the vitrified microspheres is 70-120 kg / cm³, and the particle size is 70-90 mesh. The fluorine-fixing agent is one of polyferric sulfate, polyaluminum chloride, aluminum oxide and calcium chloride, and the water-retaining agent is one of hydroxyethyl cellulose, hydroxyethyl methyl cellulose ether and hydroxypropyl methyl cellulose ether.

[0025] The air-entraining agent is one of rosin resin air-entraining agents, alkyl sulfate air-entraining agents, alkylbenzene sulfonate air-entraining agents, and fatty alcohol sulfonate air-entraining agents; the retarder is one of sodium gluconate, tartaric acid, borax, lignin sulfonate, sodium carboxymethyl cellulose, phosphoric acid and protein retarder; the starch ether is one of silicate mineral materials and ether materials; the fluoride ion content in the gypsum clinker is 20-1000 mg / kg, and the fluoride ion content is reduced to less than 0.02% by adding a fluoride-fixing agent.

[0026] Example 1: Formula: 88 parts of gypsum clinker, 6 parts of vitrified microspheres, 3 parts of heavy calcium carbonate, 0.15 parts of water retaining agent, 0.003 parts of air entraining agent, 0.1 parts of retarder, 0.3 parts of starch ether, and 0.1 parts of fluorine-fixing agent; Preparation steps: S1, weighing gypsum clinker, vitrified microspheres, heavy calcium carbonate, water-retaining agent, air-entraining agent, retarder, starch ether and fluorine-fixing agent in proportion to ensure accurate proportion of each component; S2. Hydrolyzing the fluorine-fixing agent to generate polynuclear ions with high positive charges, the hydrolysis conditions are a temperature of 70° C., a reaction time of 30 minutes, and adjusting the pH value with chlorinated acid; S3. Mixing the hydrolyzed fluorine-fixing agent with other raw materials to ensure that the fluorine-fixing agent is fully in contact with the fluoride ions and undergoes a complexation reaction; S4. During the mixing process, keep stirring evenly, control the temperature at 25°C, mix for 10 minutes, and regularly sample to detect the removal of fluoride ions; S5. After the reaction is completed, the fluoride ion content is detected. If the target fluorine content is not reached, the amount of fluorine-fixing agent is increased and mixing is continued; S6. Drying and crushing the final gypsum clinker treated with the fluorine-fixing agent to obtain a plaster gypsum with a low fluoride ion content.

[0027] Example 2: Formula: 85 parts of gypsum clinker, 7 parts of vitrified microspheres, 4 parts of heavy calcium carbonate, 0.2 parts of water-retaining agent, 0.004 parts of air-entraining agent, 0.12 parts of retarder, 0.35 parts of starch ether, and 0.15 parts of fluorine-fixing agent; Preparation steps: S1. Weigh gypsum clinker, vitrified microspheres, heavy calcium carbonate, water-retaining agent, air-entraining agent, retarder, starch ether and fluorine-fixing agent according to proportion; S2, the fluorine-fixing agent is hydrolyzed under acidic conditions at a temperature of 60°C for 25 minutes, the pH value is adjusted using chlorinated acid, and a surfactant is added; S3, mixing the hydrolyzed fluorine-fixing agent with other raw materials, stirring at a temperature of 20 ° C for 5 minutes to ensure that the fluorine-fixing agent reacts with fluoride ions; S4. Regularly testing the fluoride ion content in the mixture and determining whether the reaction is complete based on changes in fluoride ion concentration; S5. After the reaction is completed, the fluoride ion content is tested. If it does not meet the standard, add fluorine-fixing agent and remix; S6. Drying and crushing the treated gypsum clinker to obtain a final low-fluoride ion content plastering gypsum.

[0028] In summary, the advantages of the present invention are: Through the hydrolysis and complexation reaction of the fluorine-fixing agent, the fluorine content in the plaster can be effectively reduced, ensuring that the product meets environmental protection and quality standards; The optimized hydrolysis conditions and reaction process increase the reaction rate of the fluorine-fixing agent, ensure the full reaction between fluoride ions and the fluorine-fixing agent, and reduce the amount of fluorine-fixing agent used; The ultrafiltration technology and ion exchange resin used improve the reaction efficiency, remove impurities generated during the reaction, and further improve the purity of the product; The production process of low-fluorine gypsum is stable, and the final product has good water retention, strength and crack resistance, and can be widely used in the field of building plastering.

[0029] It should be noted that, in the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0030] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0031] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for improving the fluorine content in plastering gypsum, characterized in that: include: Prepare raw materials, including 88 parts of gypsum clinker, 6 parts of vitrified microspheres, 3 parts of heavy calcium carbonate, 0.15 parts of water retaining agent, 0.003 parts of air entraining agent, 0.1 parts of retarder, 0.3 parts of starch ether and 0.1 parts of fluorine-fixing agent; Hydrolyze the fluorine-fixing agent to generate polynuclear ions with high positive charges; The prepared fluorine-fixing agent is mixed with the raw materials of the plastering gypsum in proportion, so that the fluorine-fixing agent contacts the fluoride ions and undergoes a complex reaction to form a complex; Control the mixing time and detect the change in the fluoride ion content during the reaction to determine whether the reaction is complete; After the reaction is completed, the fluoride ion content in the plaster is tested. If the fluoride ion content does not meet the standard, the amount of fluoride-fixing agent is increased; The plastering gypsum treated with the fluorine-fixing agent is dried and crushed to obtain the final plastering gypsum with low fluoride ion content.

2. A method for improving the fluorine content in plastering gypsum according to claim 1, characterized in that: The hydrolysis of the fluorine-fixing agent to generate polynuclear ions with high positive charges specifically includes: Acidic hydrolysis conditions are used to promote the release of metal ions in the fluorine-fixing agent, and chlorinated acid is used to adjust the pH value to form polynuclear ions with high positive charges; In the hydrolysis reaction, adding surfactant increases the hydrolysis rate and accelerates the release of ions; Control the temperature and time of the hydrolysis reaction of the fluorine-fixing agent, the temperature is between 50°C and 70°C, and the reaction time is controlled within 20 to 40 minutes; During the hydrolysis process, ion exchange resin is introduced to improve the adsorption and complexation effect of fluoride ions and accelerate the combination of fluoride ions with high-valent polynuclear ions in the fluoride-fixing agent; After the hydrolysis reaction is completed, the hydrolysis solution is treated by ultrafiltration technology to remove substances and impurities that have not been completely reacted during the reaction process.

3. A method for improving the fluorine content in plaster according to claim 1, characterized in that: The method of mixing the prepared fluorine-fixing agent with the raw materials of the plastering gypsum in proportion, allowing the fluorine-fixing agent to contact with the fluoride ions and undergoing a complex reaction to form a complex specifically includes: Put the raw materials and the fluorine-fixing agent into the mixing equipment in proportion. During the mixing process, keep stirring evenly to promote the complexation reaction between the fluorine-fixing agent and fluoride ions; Maintain the reaction temperature between 20°C and 30°C, and control the initial mixing time to 5-10 minutes; Sampling was performed regularly to detect changes in the fluoride ion content, and the removal of fluoride ions during the reaction was monitored in real time.

4. A method for improving the fluorine content in plastering gypsum according to claim 1, characterized in that: The controlling of the mixing time and detecting the change in the content of fluoride ions during the reaction to determine whether the reaction is complete specifically include: The fluoride ion content of each sample is tested, and the fluoride ion concentration in the sample liquid is monitored in real time using a fluoride ion selective electrode. The test results are recorded and a graph showing the change in fluoride ion concentration over time is drawn; The change in fluoride ion concentration is used to determine whether the reaction is nearly complete. If the fluoride ion concentration decreases to a value close to the predetermined target value, the reaction is nearly complete. When the change in the fluoride ion content during the sampling process tends to be stable and reaches the preset target concentration, the reaction is judged to be complete.

5. A method for improving the fluorine content in plastering gypsum according to claim 1, characterized in that: After the reaction is completed, the fluoride ion content in the plaster is detected. If the fluoride ion content does not meet the standard, the amount of the fluoride-fixing agent is increased, specifically including: According to the difference between the current fluoride ion content and the target content, the amount of fluoride-fixing agent to be added is recalculated, and the fluoride-fixing agent is prepared according to the calculated result; Add the fluorine-fixing agent to the reaction system by weighing. After adding the fluorine-fixing agent, continue to stir and mix to ensure that the fluorine-fixing agent is completely dissolved; Continue to monitor the reaction until the fluoride ion concentration reaches the target requirement. After adding the fluoride-fixing agent and completing the mixing reaction, test the fluoride ion concentration again and compare the fluoride ion content at this time with the target value to ensure that the standard has been met.

6. A plastering plaster, characterized in that: It is composed of the following raw materials in parts by weight: 80-95 parts of gypsum clinker, 3-10 parts of vitrified microspheres, 0.5-10 parts of heavy calcium carbonate, 0.05-0.30 parts of water retaining agent, 0.001-0.01 parts of air entraining agent, 0.05-0.15 parts of retarder, 0.1-0.5 parts of starch ether, and 0.01-0.20 parts of fluorine-fixing agent.

7. A plastering plaster according to claim 6, characterized in that: The gypsum clinker is one of phosphogypsum and fluorgypsum, the fluoride ion content in the phosphogypsum is 20-1000 mg / kg, the particle size of the heavy calcium carbonate is 200-325 mesh, the bulk density of the vitrified microspheres is 70-120 kg / cm³, and the particle size is 70-90 mesh, the fluorine-fixing agent is one of polyferric sulfate, polyaluminum chloride, aluminum oxide and calcium chloride, and the water-retaining agent is one of hydroxyethyl cellulose, hydroxyethyl methyl cellulose ether and hydroxypropyl methyl cellulose ether.

8. The plaster according to claim 6, characterized in that: The air entraining agent is one of rosin resin air entraining agent, alkyl sulfate air entraining agent, alkylbenzene sulfonate air entraining agent and fatty alcohol sulfonate air entraining agent.

9. A plastering plaster according to claim 6, characterized in that: The retarder is one of sodium gluconate, tartaric acid, borax, lignin sulfonate, sodium carboxymethyl cellulose, phosphoric acid and protein retarders.

10. The plaster according to claim 6, characterized in that: The starch ether is one of a silicate mineral material and an ether material. The fluoride ion content in the gypsum clinker is 20-1000 mg / kg, and the fluoride ion content is reduced to less than 0.02% by adding a fluoride-fixing agent.

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