A method for preparing a lightweight plastering gypsum

Abstract

The application provides a preparation method of light plastering gypsum. By mixing and stirring specific proportions of building gypsum, II anhydrous hard gypsum, self-made light gypsum sand and additives, the mechanical strength of the prepared light plastering gypsum can reach excellent performance such as a tensile bonding strength of 0.7-1.0 MPa under standard conditions and a tensile bonding strength of 0.3-0.6 MPa under wet conditions, which is greatly improved compared with the existing light plastering gypsum with a tensile bonding strength of ≥0.4 MPa under standard conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building materials, and in particular to a preparation method of light plastering gypsum. BACKGROUND

[0002] Light plastering gypsum is a kind of green and environmentally friendly plastering material on the market at present. Its emergence has changed the traditional plastering method with cement-based binder. Gypsum plastering can not only avoid the problems of large dry shrinkage, poor adhesion, expansion cracking and hollowing caused by traditional cement plastering, but also has a wide source of gypsum and a shorter construction period, so that the cost of engineering materials and labor cost are reduced, and the construction progress is accelerated. In addition, the bulk density of light plastering gypsum is smaller, which can not only reduce the load of the base body, but also reduce the energy consumption of buildings due to the lower thermal conductivity. Under the form of national vigorous promotion of energy saving and emission reduction, light plastering gypsum instead of traditional cement plastering will become a development trend, and the research on the preparation and performance of light plastering gypsum has theoretical significance and use value for plastering materials.

[0003] CN113024210A discloses a kind of light plastering gypsum, which is mainly composed of hemihydrate gypsum, cellulose ether, thixotropic agent, organic bentonite, retarder and vitrified microsphere.The production steps are as follows:(1) the hemihydrate gypsum, cellulose ether 100, thixotropic agent 4510, organic bentonite 1201 and retarder 5001 are mixed and stirred uniformly according to the above ratio;(2) the vitrified beads are added to the mixed powder in step (1), and the reaction is waited for 30 minutes, and the final setting time is 90-120 minutes.The light plastering gypsum not only meets the requirements of relevant standards, but also has the advantages of corrosion resistance, mildew resistance and moisture resistance.But it still cannot meet the requirements of light plastering gypsum with high coating rate, light weight and high strength.

[0004] CN115108796B discloses a kind of light plastering gypsum and its preparation method, which includes the following raw materials by weight:700-760 parts of desulfurization gypsum, 135-170 parts of stone powder, 85-95 parts of vitrified microsphere, 1.5-3.5 parts of ramie fiber, 0.8-1.5 parts of straw fiber, 0.3-0.7 parts of starch ether, 0.8-1.5 parts of thixotropic agent, 1-5 parts of retarder, 1.0-2.5 parts of cellulose ether.The preparation method is as follows:step 1):mix the retarder, ramie fiber, straw fiber and cellulose ether uniformly to obtain a first mixture;step 2):mix the desulfurization gypsum, vitrified microsphere and stone powder uniformly to obtain a second mixture;step 3):mix the starch enzyme, thixotropic agent and retarder uniformly to obtain a third mixture;step 4):mix the first mixture, second mixture and third mixture uniformly to obtain the finished product.But it still cannot meet the requirements of light plastering gypsum with light weight and high strength.

[0005] CN115159939A discloses a light plastering gypsum mortar preparation method, solves the problem of high impurity content and poor bonding strength of the light plastering gypsum mortar in the prior art. Among them, the preparation method comprises the following raw materials by weight: gypsum 60-65 parts, heavy calcium powder 10-15 parts, sand powder 10-15 parts, light aggregate 15-20 parts, cellulose ether 10-30 parts, sodium silicate 0.3-0.5 parts. By adding heavy calcium powder, the water retention rate of the finished mortar product is improved, the mortar setting time and apparent density are reduced, by adding light aggregate, the workability and self-strength of the mortar are improved, the material shrinkage rate is reduced, the raw material cost is reduced, by adding cellulose ether, the mortar has good construction performance, and by adding carbon fiber, the comprehensive performance of the gypsum mortar such as tensile strength, bending strength and compressive strength is improved. But it still can not meet the requirements of light plastering gypsum with light weight and high strength.

[0006] In view of the high coating rate and low strength of the existing light plastering gypsum, the problem of the present application is to develop a preparation method of light plastering gypsum with low density, high strength, water resistance, mildew resistance and crack resistance, which can solve the problems of high coating rate, low strength, large use of expensive vitrified microbeads, poor water resistance, mildew resistance, density and other performance. SUMMARY

[0007] In view of the defects of the prior art, the present application provides a preparation method of light plastering gypsum. By mixing specific proportions of building gypsum, type II anhydrous hard gypsum, self-made light gypsum sand and additives through stirring and mixing, the mechanical strength of the light plastering gypsum can reach excellent performance such as tensile bonding strength of 0.7-1.0 MPa under standard conditions and tensile bonding strength of 0.3-0.6 MPa under humid conditions, which is greatly improved compared with the existing light plastering gypsum with tensile bonding strength ≥0.4 MPa under standard conditions.

[0008] The technical scheme of the present application is as follows:

[0009] The present application provides a preparation method of light plastering gypsum, and the raw materials of the light plastering gypsum comprise the following components by weight:

[0010] Building gypsum: 30-50 parts;

[0011] Type II anhydrous hard gypsum: 10-30 parts;

[0012] 42.5 gray cement: 1-5 parts;

[0013] Light gypsum sand: 30-50 parts;

[0014] Thixotropic agent: 0.1-1 part;

[0015] Starch ether: 0.01-0.06 parts;

[0016] Cellulose ether: 0.2-0.5 parts;

[0017] Air-entraining agent: 0.005-0.01 parts;

[0018] Water-retaining agent: 0.005 parts - 0.02 parts;

[0019] Activator: 1-8 parts; and

[0020] Retarder: 0.1-0.5 parts.

[0021] Furthermore, the building gypsum meets the following mass percentage requirements: hemihydrate phase ≥ 80%, dihydrate phase ≤ 4%, and anhydrous phase ≤ 5%. The building gypsum has a 2-hour flexural strength ≥ 3.0 MPa, a 2-hour compressive strength ≥ 6.0 MPa, and a chloride ion content ≤ 600 mg / kg.

[0022] Furthermore, the type II anhydrous gypsum is required to meet the following requirements: a mass percentage of type II anhydrous gypsum ≥ 96%, a softening coefficient between 0.6 and 0.7, and a pH value between 12 and 13.

[0023] Further, the 42.5 lime cement comprises the following components by weight percentage: cement chemical composition CaO 60%-65%, SiO2 18%-19%, Al2O3 4%-5%, Fe2O3 2%-3%, MgO 2%-3%, and SO3 3%-4%, based on the total weight of the 42.5 lime cement. The 42.5 lime cement has a calcination strength ≤3%, NaOequi (representing basic oxides) ≤1%, 3-day compressive strength ≥3.5 MPa, 3-day compressive strength ≥17 MPa, 28-day flexural strength ≥6.5 MPa, and 28-day compressive strength ≥42.5 MPa.

[0024] Furthermore, the particle size of the lightweight gypsum sand is 40-140 mesh, and the CaSO4 content is ≥90%.

[0025] Furthermore, the thixotropic agent is a bentonite-based thixotropic agent.

[0026] Furthermore, the starch ether has a water content of 5%, a pH value between 6.0 and 8.0, and a viscosity of 400-1200 mPa·s.

[0027] Furthermore, the cellulose ether is hydroxypropyl methylcellulose (HPMC) with a viscosity of 40,000-150,000 mPa·s.

[0028] Furthermore, the air-entraining agent is one or more combinations of rosin resins, alkyl and alkyl aromatic sulfonic acids, fatty alcohol sulfonates, saponins, protein salts, and petroleum sulfonate hydrochloric acid.

[0029] Furthermore, the water-retaining and thickening agent is polyacrylamide, which is used to increase the water retention, cohesiveness, and workability of cement mortar.

[0030] Furthermore, the activator is one or a combination of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate.

[0031] Furthermore, the retarder is a protein-based gypsum retarder.

[0032] Furthermore, the preparation method of the lightweight plastering gypsum includes the following steps:

[0033] Step 1: Add building gypsum, anhydrous gypsum II, and lightweight gypsum sand to a mixing tank, and stir and mix in the mixing tank for 3-5 minutes to obtain a mixture of adhesive and aggregate.

[0034] Step 2: Pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air-entraining agent and heavy calcium carbonate to obtain a mixture of additives;

[0035] Step 3: Add the additive mixture to the mixing tank and dry mix it with the adhesive and aggregate mixture for 3-5 minutes to obtain the lightweight plaster.

[0036] Furthermore, in step 2, the amount of added heavy calcium carbonate is 2 kg.

[0037] The early strength of the lightweight plastering gypsum of this invention is provided by building gypsum during construction, while the later strength is provided by Type II anhydrous hard gypsum. The reaction mechanism is as follows:

[0038] Reaction 1: CaSO4·0.5H2O + 1.5H2O → CaSO4·2H2O + Q (19.2 J / g SO3)

[0039] Reaction 2: mCaSO4 (type II anhydrous gypsum) + salt (activator) + 2H2O → salt.mCaSO4.nH2O (double salt)

[0040] Salt.mCaSO4.nH2O + 2mH2O → m(CaSO4.2H2O) + Salt.nH2O

[0041] Reaction 1 involves the reaction of building gypsum (β-hemihydrate gypsum) with water to produce gypsum dihydrate. Reaction 2 involves the reaction of type II anhydrous gypsum with an activator to generate unstable mCaSO4·nH2O (double salt), which then decomposes into gypsum dihydrate. This process is repeated through the intermediate hydrate (mCaSO4·nH2O) to transform back into gypsum dihydrate, thereby accelerating the dissolution of type II anhydrous gypsum.

[0042] In this invention, the lightweight gypsum sand serves as aggregate, acting as a skeleton and filler in the lightweight plastering gypsum.

[0043] In this invention, the cellulose ether acts as a water-retaining and thickening agent, primarily serving to retain water and increase viscosity.

[0044] In this invention, the thixotropic agent is bentonite. Its mechanism of action in plaster is as follows: Bentonite is an expansive clay material primarily composed of montmorillonite. During its expansion process, it absorbs a large amount of water, up to 10 times its own weight, and can expand to 20-30 times its own volume. This reduces the free water in the cement mortar, leading to a decrease in the mortar's fluidity and a rapid loss of fluidity. The main component of bentonite is montmorillonite, which accounts for approximately 65% ​​and has a columnar internal structure. After hydrolysis, it improves the stability of cement mortar in lightweight plaster, and its unique sliding effect improves the mortar's sliding performance and pumpability to a certain extent.

[0045] In this invention, the mechanism of action of the air-entraining agent in lightweight plaster is as follows: the air-entraining agent generates foam in water, forming a gas-liquid dispersion system. The air-entraining agent is adsorbed on the gas-liquid interface and reduces its surface tension. Adding the air-entraining agent significantly reduces the surface tension of the solution, resulting in fine, uniform, and regularly shaped spherical bubbles. The fine aggregate particles in the cement mortar, like a four-dimensional network, support the bubbles, helping to stabilize them. When the dosage is appropriate, it has no significant impact on the strength of the hardened mortar and can greatly improve the workability and durability of the cement mortar.

[0046] In this invention, the mechanism of polyacrylamide's effect on the hydration of building gypsum is as follows: on the one hand, it interacts with the Ca in building gypsum. 2+ The interaction generates compounds that fill the gaps between calcium sulfate dihydrate crystals, a hydration product of building gypsum; on the other hand, polyacrylamide molecules encapsulate the desulfurized building gypsum particles, thereby hindering the hydration reaction with water, thus improving the product's water retention, cohesiveness, and workability.

[0047] In this invention, the mechanism of action of the protein-based retarder is mainly to inhibit the rate of crystallization and reduce the solubility of hemihydrate gypsum, thereby slowing down the crystallization process of hemihydrate gypsum to dihydrate gypsum and delaying the setting time of gypsum.

[0048] Furthermore, the method for preparing the lightweight gypsum sand includes:

[0049] Based on the total mass of raw materials, the percentage content of the raw materials in the lightweight gypsum sand is as follows: 5-10 parts of parent material particles, 65-80 parts of main material 1, 10-15 parts of main material 2, 2-5 parts of auxiliary materials, 3-5 parts of pelletizing material, and the remainder is dispersant.

[0050] Parent material particles: perlite filter aid with a particle size ≤ 0.102 mm;

[0051] Main material 1: Any one or a mixture of any two or more of the following: natural gypsum, desulfurized gypsum, phosphogypsum, fluorogypsum, titanium gypsum, or other industrial by-product gypsum;

[0052] Main material 2: Any one or a mixture of any two or more of the following: aluminate compounds, siliceous aluminate minerals, kaolin minerals, dolomite, soluble oxides, and aluminum oxide;

[0053] Auxiliary materials: any one or a mixture of two of activated calcium and slaked lime;

[0054] Pelletizing material: any one or a mixture of two or more of clay, lignin cellulose or bentonite, with a particle size ≤0.048mm;

[0055] Dispersant: Sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, or any one or a mixture of two of polycarboxylate;

[0056] Preparation methods include:

[0057] (1) Grinding: Main material 1, main material 2, auxiliary material and pelletizing material are ground to 0.037±0.005mm respectively;

[0058] (2) Mud reaction: Add appropriate amount of water to the main material 1, main material 2, auxiliary material and pelletizing material and stir thoroughly in the mixing tank. The speed is 50-300 r / min and the stirring time is 5-10 min. At this time, the various materials are fully dispersed in the water to form mud liquid, and the various materials can fully contact and mix evenly.

[0059] (3) Dehydration: The mud slurry after the mud reaction is dehydrated by centrifugation, adsorption, and extrusion, and then dried at 150-250℃ to control the water content of the mud slurry to be below 3% by mass, so as to obtain block material.

[0060] (4) Grinding: The block material is ground by a high-speed grinding mill at a speed of 3000-6000 r / min to a powder size of 0.037±0.005 mm;

[0061] (5) Formation of mother ball: The mother ball is poured into a round pot granulator, and water is sprayed through the water spraying component of the granulator to form particles A. 1 / 3 to 1 / 2 of the total weight of the powder is added to particles A, and the mother ball is formed by continuing to rotate rapidly in the ball mill.

[0062] (6) Spherical formation: While the mother ball is being sprayed with water mist in the granulator, the remaining powder is added while spraying. As the ball mill rotates rapidly, the mother ball gradually grows to form the first sphere. At this point, no more water spraying is needed. Then, the dispersant is added to form the second spherical particles.

[0063] (7) Sieving: Remove the coarse particles from the second spherical particles obtained in step (6), leaving particles of 40-140 mesh for later use;

[0064] (8) Spherical shaping: The 40-140 mesh particles obtained in step (7) are spherical shaped again to form more rounded spheres. The sphericity of the rounded spheres after the shaping operation reaches more than 98%.

[0065] (9) Curing: Send the round sphere obtained in step (8) to the curing chamber for curing. The curing is carried out in two stages: water mist curing and dry curing.

[0066] (10) The spherical particles obtained in step (9) are sieved to obtain lightweight gypsum sand, wherein the lightweight gypsum sand has a size of 0.106mm-0.425mm and an internal bulk density of 600kg / m³. 3 -700kg / m 3 All other indicators meet the requirements of GB / T 14684-2022 "Construction Sand".

[0067] Furthermore, in step (6), the particle size of the first sphere is 20-140 mesh.

[0068] Furthermore, in step (6), particles with a diameter ≥ 0.425 mm are removed.

[0069] Further, the curing in step (9) is as follows: water mist curing lasts for 4-7 days, each water spray lasts for 4 hours, spraying once a day, and the temperature of the curing chamber is 15-25 degrees Celsius; then it is transferred to the next curing chamber for dry curing, and the room temperature is maintained for dry curing for 11-14 days. The principle of the curing stage is: to make the gypsum in the raw material react with the gypsum reactant (main material 2) to form ceramic spheres, thereby giving the product high strength and water resistance. For example, the cylinder compressive strength is 4-6MPa, the mass loss rate of the ceramic spheres is less than 5% (high strength), which meets the requirements of GB / T 14684-2022 "Construction Sand" Class I standard, the water absorption rate is 6-7%, the softening coefficient is 0.76, and it has high water resistance, which has a high strength and water resistance effect for the plastering gypsum to be formed later.

[0070] The beneficial effects of this invention are as follows:

[0071] (1) In the prior art, the coating rate of plastering gypsum is mainly provided by vitrified microspheres, lightweight aggregates, etc., and all of them follow the rule that the higher the coating rate, the lower the flexural and compressive strength. This is because the higher the coating rate, the more pores will be generated in the hardened slurry of lightweight plastering gypsum, which leads to a decrease in its strength as the coating rate increases. However, the coating rate in this invention is provided by lightweight gypsum sand. Since the CaSO4 content of gypsum sand is ≥90%, the addition of lightweight gypsum sand will reduce the amount of building gypsum to be added, and the density of gypsum sand is 600 kg / m³. 3 This results in the lightweight plastering gypsum of the present invention having a bulk density of approximately 600 kg / m³. 3 -750Kg / m 3 Between these, the density is extremely light.

[0072] (2) The present invention incorporates anhydrous gypsum II and adds an activator, which ensures the high strength of the lightweight plastering gypsum in the later stage. On the other hand, the incorporation of anhydrous gypsum II and gypsum sand can improve the water resistance and mildew resistance of the product.

[0073] (3) The lightweight plastering gypsum uses a type of gypsum sand, which has the characteristics of being non-fired, high-strength, water-resistant, energy-saving and environmentally friendly, and reducing energy consumption; the gypsum sand is prepared by one or any two of desulfurized gypsum, natural gypsum, fluorogypsum, phosphogypsum, titanium gypsum or other industrial by-product gypsum.

[0074] (4) This invention uses self-developed gypsum sand, combined with building gypsum and II anhydrous hard gypsum, to produce a lightweight plastering gypsum. It achieves excellent performance in terms of mechanical strength, bulk density, mildew resistance, coating rate, and crack resistance. The coating rate is between 130-140%, and the bulk density is 600 kg / m³. 3 -750Kg / m 3 The tensile bond strength under standard conditions is 0.7-1.0 MPa, and the tensile bond strength under wet conditions is 0.3-0.6 MPa.

[0075] (5) This invention utilizes industrial waste to produce lightweight plastering gypsum, turning waste into treasure. Moreover, it uses gypsum sand to replace building sand, thereby solving the shortage of sand resources. The cost is reduced by about half compared to building sand, resulting in higher economic benefits. Attached Figure Description

[0076] Figure 1 This is a flow chart of the preparation process of the lightweight plastering gypsum of the present invention. Detailed Implementation

[0077] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0078] Example 1

[0079] A method for preparing a lightweight plastering gypsum includes the following steps:

[0080] Step 1: Add building gypsum, anhydrous gypsum II and lightweight gypsum sand to the mixing tank, and stir and mix for 3-5 minutes to obtain a mixture of adhesive and aggregate.

[0081] Step 2: Pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air-entraining agent and 2 kg of heavy calcium carbonate to obtain an additive mixture;

[0082] Step 3: Add the additive mixture to the mixing tank and dry mix it with the adhesive and aggregate mixture for 3-5 minutes to obtain lightweight plaster.

[0083] The weight proportions of each material are as follows:

[0084] 40 parts building gypsum, 28 parts type II anhydrous gypsum, 2 parts cement, 30 parts lightweight gypsum sand, 0.2 parts thixotropic agent, 0.01 parts starch ether, 0.3 parts cellulose ether, 0.01 parts air-entraining agent, 4 parts activator, 0.005 parts polyacrylamide, and 0.2 parts retarder;

[0085] The thixotropic agent is bentonite; the air-entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonates, fatty alcohol sulfonates, saponins, protein salts, and petroleum sulfonate hydrochloric acid; the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate; and the retarder is a protein-based gypsum retarder. The specific properties of lightweight plastering gypsum are shown in Table 2.

[0086] The lightweight gypsum sand used in the lightweight plastering gypsum of Example 1 is prepared by the following method:

[0087] Based on the total mass of raw materials, the percentage content of raw materials in lightweight gypsum sand is as follows:

[0088] Parent material: Perlite filter aid with a particle size ≤ 0.102 mm, 5 parts;

[0089] Main material 1: 32 parts desulfurized gypsum, 30 parts natural gypsum and 5 parts fluorogypsum;

[0090] Main ingredient 2: 5 parts aluminate compound and 5 parts kaolin mineral;

[0091] Auxiliary materials: 3 parts quicklime and 2 parts activated calcium;

[0092] pelletizing materials: 1 part clay, 2 parts bentonite and 1 part lignin cellulose;

[0093] Dispersant: 3 parts sodium pyrophosphate, 3 parts polycarboxylate, 3 parts sodium tripolyphosphate;

[0094] Preparation methods include:

[0095] (1) Grinding: Main material 1, main material 2, auxiliary material and pelletizing material are ground to 0.037±0.005mm respectively;

[0096] (2) Mud reaction: Add appropriate amount of water to the main material 1, main material 2, auxiliary material and pelletizing material and stir thoroughly in the mixing tank at a speed of 300 r / min for 7 min. At this time, the various materials are fully dispersed in the water to form mud liquid, and the various materials can fully contact and mix evenly.

[0097] (3) Dehydration: The mud slurry after the mud reaction is dehydrated by centrifugation, adsorption, and extrusion, and then dried at 200℃ to control the water content of the mud slurry to below 3% by mass, so as to obtain block material.

[0098] (4) Grinding: Grind the lumpy material into powder using a high-speed grinding mill at a speed of 3000 r / min to a particle size of 0.036 mm;

[0099] (5) Formation of mother ball: Pour the mother ball into the round pot granulator, and spray water to form granules A through the water spraying component of the granulator. Add 1 / 3 of the total weight of powder to granules A, and continue to form mother balls under the rapid rotation in the ball mill.

[0100] (6) Spherical formation: While the mother ball is being sprayed with water mist in the granulator, the remaining powder is added while spraying. As the ball mill rotates rapidly, the mother ball gradually grows larger to form the first spherical. At this point, no more water spraying is needed. Then, a dispersant is added to form the second spherical particles.

[0101] (7) Sieving: Remove the coarse particles from the second spherical particles obtained in step (6), leaving particles of 40-140 mesh for later use;

[0102] (8) Spherical shaping: The 40-140 mesh particles obtained in step (7) are spherically shaped again to form more rounded spheres. The sphericity of the rounded spheres after the shaping operation reaches more than 98%.

[0103] (9) Curing: Send the round sphere obtained in step (8) to the curing chamber for curing. The curing is carried out in two stages: water mist curing and dry curing.

[0104] (10) The spherical particles obtained in step (9) are sieved to obtain lightweight gypsum sand sample 1. The lightweight gypsum sand has a size of 0.106mm-0.425mm and an internal bulk density of 600kg / m³. 3 -700kg / m 3 All other indicators meet the requirements of GB / T 14684-2022 "Construction Sand".

[0105] The curing process in step (9) involves water mist curing for 4-7 days, with each water mist spraying lasting 4 hours, once a day, and the curing chamber temperature maintained at 15-25 degrees Celsius. The product is then transferred to the next curing chamber for dry curing, with the room temperature maintained for 11-14 days. The principle of the curing stage is to cause the gypsum in the raw materials to undergo a ceramicization reaction with the gypsum reactant (main material 2) to form ceramic spherical particles, thereby giving the product higher strength and water resistance. Specific performance details are shown in Table 1.

[0106] Example 2

[0107] A method for preparing a lightweight plastering gypsum includes the following steps:

[0108] Step 1: Add building gypsum, anhydrous gypsum II and lightweight gypsum sand to the mixing tank, and stir and mix for 3-5 minutes to obtain a mixture of adhesive and aggregate.

[0109] Step 2: Pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air-entraining agent and 2 kg of heavy calcium carbonate to obtain an additive mixture;

[0110] Step 3: Add the additive mixture to the mixing tank and dry mix it with the adhesive and aggregate mixture for 3-5 minutes to obtain lightweight plaster.

[0111] The weight proportions of each material are as follows:

[0112] 50 parts building gypsum, 20 parts type II anhydrous gypsum, 3 parts cement, 27 parts lightweight gypsum sand, 0.1 parts thixotropic agent, 0.02 parts starch ether, 0.25 parts cellulose ether, 0.006 parts air-entraining agent, 2 parts activator, 0.007 parts polyacrylamide, and 0.3 parts retarder;

[0113] The thixotropic agent is bentonite; the air-entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonates, fatty alcohol sulfonates, saponins, protein salts, and petroleum sulfonate hydrochloric acid; the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate; and the retarder is a protein-based gypsum retarder. The specific properties of lightweight plastering gypsum are shown in Table 2.

[0114] The lightweight gypsum sand used in the lightweight plastering gypsum of Example 2 is prepared by the following method:

[0115] Based on the total mass of raw materials, the percentage content of raw materials in lightweight gypsum sand is as follows:

[0116] Parent material: Perlite filter aid with a particle size ≤ 0.102 mm, 7 parts;

[0117] Main material 1: 34 parts desulfurized gypsum, 21 parts natural gypsum, 2 parts titanium gypsum and 3 parts phosphogypsum;

[0118] Main material 2: 5 parts soluble oxide, 10 parts aluminum oxide and 1 part dolomite;

[0119] Auxiliary materials: 3 parts quicklime;

[0120] pelletizing materials: 1 part clay, 1 part bentonite and 2 parts lignin cellulose;

[0121] Dispersant: 2 parts sodium pyrophosphate, 3 parts sodium hexametaphosphate and 5 parts sodium tripolyphosphate;

[0122] Preparation methods include:

[0123] (1) Grinding: Main material 1, main material 2, auxiliary material and pelletizing material are ground to 0.037mm respectively;

[0124] (2) Mud reaction: Add appropriate amount of water to the main material 1, main material 2, auxiliary material and pelletizing material and stir thoroughly in the mixing tank at a speed of 150 r / min for 5 min. At this time, the various materials are fully dispersed in the water to form mud liquid, and the various materials can fully contact and mix evenly.

[0125] (3) Dehydration: The mud slurry after the mud reaction is dehydrated by centrifugation, adsorption, and extrusion, and then dried at 150℃ to control the water content of the mud slurry to below 3% by mass, so as to obtain block material.

[0126] (4) Grinding: Grind the lumpy material into powder using a high-speed grinding mill at a speed of 4000 r / min to a particle size of 0.037 mm;

[0127] (5) Formation of mother ball: Pour the mother ball into the round pot granulator, and spray water to form granules A through the water spraying component of the granulator. Add 1 / 2 of the total weight of powder to granules A, and continue to form mother balls under the rapid rotation in the ball mill.

[0128] (6) Spherical formation: While the mother ball is being sprayed with water mist in the granulator, the remaining powder is added while spraying. As the ball mill rotates rapidly, the mother ball gradually grows larger to form the first spherical. At this point, no more water spraying is needed. Then, a dispersant is added to form the second spherical particles.

[0129] (7) Sieving: Remove the coarse particles from the second spherical particles obtained in step (6), leaving particles of 40-140 mesh for later use;

[0130] (8) Spherical shaping: The 40-140 mesh particles obtained in step (7) are spherically shaped again to form more rounded spheres. The sphericity of the rounded spheres after the shaping operation reaches more than 98%.

[0131] (9) Curing: Send the round sphere obtained in step (8) to the curing chamber for curing. The curing is carried out in two stages: water mist curing and dry curing.

[0132] (10) The spherical particles obtained in step (9) are sieved to obtain lightweight gypsum sand sample 2. The lightweight gypsum sand has a size of 0.106mm-0.425mm and an internal bulk density of 600kg / m³. 3 -700kg / m 3 All other indicators meet the requirements of GB / T 14684-2022 "Construction Sand".

[0133] The curing process in step (9) involves water mist curing for 7 days, with each water mist spraying lasting 4 hours, once a day, and the curing chamber temperature maintained at 25 degrees Celsius. Then, the product is moved to the next curing chamber for dry curing, maintaining dry curing at room temperature for 12 days. The principle of the curing stage is to cause the gypsum in the raw materials to undergo a ceramicization reaction with the gypsum reactant (main material 2) to form ceramic spherical particles, thereby giving the product higher strength and water resistance. Specific performance details are shown in Table 1.

[0134] Example 3

[0135] A method for preparing a lightweight plastering gypsum includes the following steps:

[0136] Step 1: Add building gypsum, anhydrous gypsum II and lightweight gypsum sand to the mixing tank, and stir and mix for 3-5 minutes to obtain a mixture of adhesive and aggregate.

[0137] Step 2: Pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air-entraining agent and 2 kg of heavy calcium carbonate to obtain an additive mixture;

[0138] Step 3: Add the additive mixture to the mixing tank and dry mix it with the adhesive and aggregate mixture for 3-5 minutes to obtain lightweight plaster.

[0139] The weight proportions of each material are as follows:

[0140] 30 parts building gypsum, 30 parts type II anhydrous gypsum, 5 parts cement, 35 parts lightweight gypsum sand, 0.3 parts thixotropic agent, 0.03 parts starch ether, 0.35 parts cellulose ether, 0.005 parts air-entraining agent, 6 parts activator, 0.01 parts polyacrylamide, and 0.4 parts retarder;

[0141] The thixotropic agent is bentonite; the air-entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonates, fatty alcohol sulfonates, saponins, protein salts, and petroleum sulfonate hydrochloric acid; the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate; and the retarder is a protein-based gypsum retarder. The specific properties of lightweight plastering gypsum are shown in Table 2.

[0142] The lightweight gypsum sand used in the lightweight plastering gypsum of Example 3 is prepared by the following method:

[0143] Based on the total mass of raw materials, the percentage content of raw materials in lightweight gypsum sand is as follows:

[0144] Parent material: Perlite filter aid with a particle size ≤ 0.102 mm, 6 parts;

[0145] Main material 1: 34 parts desulfurized gypsum, 24 parts natural gypsum, 10 parts fluorogypsum and 5 parts phosphogypsum;

[0146] Main material 2: 5 parts of silica-alumina minerals, 3 parts of kaolin minerals, 2 parts of aluminum oxide, and 1 part of dolomite;

[0147] Auxiliary materials: 2 parts quicklime;

[0148] Ball-forming materials: 1 part clay, 2 parts bentonite, 2 parts lignin cellulose;

[0149] Dispersant: 2 parts sodium pyrophosphate, 1 part sodium hexametaphosphate;

[0150] Preparation methods include:

[0151] (1) Grinding: Main material 1, main material 2, auxiliary material and pelletizing material are ground to 0.040mm respectively;

[0152] (2) Mud reaction: Add appropriate amount of water to the main material 1, main material 2, auxiliary material and pelletizing material and stir thoroughly in the mixing tank at a speed of 300 r / min for 8 min. At this time, the various materials are fully dispersed in the water to form mud liquid, and the various materials can fully contact and mix evenly.

[0153] (3) Dehydration: The mud slurry after the mud reaction is dehydrated by centrifugation, adsorption, and extrusion, and then dried at 200℃ to control the water content of the mud slurry to below 3% by mass, so as to obtain block material.

[0154] (4) Grinding: Grind the lumpy material into powder using a high-speed grinding mill at a speed of 3000 r / min to a particle size of 0.040 mm;

[0155] (5) Formation of mother ball: Pour the mother ball into the round pot granulator, and spray water to form granules A through the water spraying component of the granulator. Add 1 / 3 of the total weight of powder to granules A, and continue to form mother balls under the rapid rotation in the ball mill.

[0156] (6) Spherical formation: While the mother ball is being sprayed with water mist in the granulator, the remaining powder is added while spraying. As the ball mill rotates rapidly, the mother ball gradually grows larger to form the first spherical. At this point, no more water spraying is needed. Then, a dispersant is added to form the second spherical particles.

[0157] (7) Sieving: Remove the coarse particles from the second spherical particles obtained in step (6), leaving particles of 40-140 mesh for later use;

[0158] (8) Spherical shaping: The 40-140 mesh particles obtained in step (7) are spherically shaped again to form more rounded spheres. The sphericity of the rounded spheres after the shaping operation reaches more than 98%.

[0159] (9) Curing: Send the round sphere obtained in step (8) to the curing chamber for curing. The curing is carried out in two stages: water mist curing and dry curing.

[0160] (10) The spherical particles obtained in step (9) are sieved to obtain lightweight gypsum sand sample 3. The lightweight gypsum sand has a size of 0.106mm-0.425mm and an internal bulk density of 600kg / m³. 3 -700kg / m 3 All other indicators meet the requirements of GB / T 14684-2022 "Construction Sand".

[0161] The curing process in step (9) involves water mist curing for 5 days, with each water mist spraying lasting 4 hours, once a day, and the curing chamber temperature maintained at 20 degrees Celsius. Then, the product is moved to the next curing chamber for dry curing, which is maintained at room temperature for 14 days. The principle of the curing stage is to cause the gypsum in the raw materials to undergo a ceramicization reaction with the gypsum reactant (main material 2) to form ceramic spherical particles, thereby giving the product higher strength and water resistance. Specific performance details are shown in Table 1.

[0162] Example 4

[0163] A method for preparing a lightweight plastering gypsum includes the following steps:

[0164] Step 1: Add building gypsum, anhydrous gypsum II and lightweight gypsum sand to the mixing tank, and stir and mix for 3-5 minutes to obtain a mixture of adhesive and aggregate.

[0165] Step 2: Pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air-entraining agent and 2 kg of heavy calcium carbonate to obtain an additive mixture;

[0166] Step 3: Add the additive mixture to the mixing tank and dry mix it with the adhesive and aggregate mixture for 3-5 minutes to obtain lightweight plaster.

[0167] The weight proportions of each material are as follows:

[0168] 45 parts building gypsum, 35 parts type II anhydrous gypsum, 3 parts cement, 27 parts lightweight gypsum sand, 0.1 parts thixotropic agent, 0.01 parts starch ether, 0.26 parts cellulose ether, 0.005 parts air-entraining agent, 6 parts activator, 0.006 parts polyacrylamide, and 0.65 parts retarder.

[0169] The thixotropic agent is bentonite; the air-entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonates, fatty alcohol sulfonates, saponins, protein salts, and petroleum sulfonate hydrochloric acid; the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate; and the retarder is a protein-based gypsum retarder. The specific properties of lightweight plastering gypsum are shown in Table 2.

[0170] The lightweight gypsum sand used in the lightweight plastering gypsum of Example 4 is prepared by the following method:

[0171] Based on the total mass of raw materials, the percentage content of raw materials in lightweight gypsum sand is as follows:

[0172] Parent material: 10 parts of perlite filter aid with a particle size ≤ 0.102 mm;

[0173] Main material 1: 30 parts desulfurized gypsum, 24 parts natural gypsum, 10 parts fluorogypsum, and 5 parts phosphogypsum;

[0174] Main material 2: 6 parts of silica-alumina minerals, 3 parts of kaolin minerals, 3 parts of aluminum oxide, and 1 part of dolomite;

[0175] Auxiliary materials: 2 parts quicklime;

[0176] pelletizing materials: 1 part clay, 2 parts bentonite, 1 part lignin cellulose;

[0177] Dispersant: 1 part sodium pyrophosphate, 1 part sodium hexametaphosphate;

[0178] Preparation methods include:

[0179] (1) Grinding: Main material 1, main material 2, auxiliary material and pelletizing material are ground to 0.041mm respectively;

[0180] (2) Mud reaction: Add appropriate amount of water to the main material 1, main material 2, auxiliary material and pelletizing material and stir thoroughly in the mixing tank. The speed is 260r / min and the stirring time is 7min. At this time, the various materials are fully dispersed in the water to form mud liquid, and the various materials can fully contact and mix evenly.

[0181] (3) Dehydration: The mud slurry after the mud reaction is dehydrated by centrifugation, adsorption, and extrusion, and then dried at 250℃ to control the water content of the mud slurry to below 3% by mass, so as to obtain block material.

[0182] (4) Grinding: Grind the lumpy material into powder using a high-speed grinding mill at a speed of 3000 r / min to a particle size of 0.041 mm;

[0183] (5) Formation of mother ball: Pour the mother ball into the round pot granulator, and spray water to form granules A through the water spraying component of the granulator. Add 1 / 3 of the total weight of powder to granules A, and continue to form mother balls under the rapid rotation in the ball mill.

[0184] (6) Spherical formation: While the mother ball is being sprayed with water mist in the granulator, the remaining powder is added while spraying. As the ball mill rotates rapidly, the mother ball gradually grows larger to form the first spherical. At this point, no more water spraying is needed. Then, a dispersant is added to form the second spherical particles.

[0185] (7) Sieving: Remove the coarse particles from the second spherical particles obtained in step (6), leaving particles of 40-140 mesh for later use;

[0186] (8) Spherical shaping: The 40-140 mesh particles obtained in step (7) are spherically shaped again to form more rounded spheres. The sphericity of the rounded spheres after the shaping operation reaches more than 98%.

[0187] (9) Curing: Send the round sphere obtained in step (8) to the curing chamber for curing. The curing is carried out in two stages: water mist curing and dry curing.

[0188] (10) The spherical particles obtained in step (9) are sieved to obtain lightweight gypsum sand sample 4. The lightweight gypsum sand has a size of 0.106mm-0.425mm and an internal bulk density of 600kg / m³. 3 -700kg / m 3 All other indicators meet the requirements of GB / T 14684-2022 "Construction Sand".

[0189] The curing process in step (9) involves water mist curing for 6 days, with each water mist spraying lasting 4 hours, once a day, and the curing chamber temperature maintained at 15 degrees Celsius. Then, the product is moved to the next curing chamber for dry curing, maintaining dry curing at room temperature for 14 days. The principle of the curing stage is to cause the gypsum in the raw materials to undergo a ceramicization reaction with the gypsum reactant (main material 2) to form ceramic spherical particles, thereby giving the product higher strength and water resistance. Specific performance details are shown in Table 1.

[0190] Example 5

[0191] A method for preparing a lightweight plastering gypsum includes the following steps:

[0192] Step 1: Add building gypsum, anhydrous gypsum II and lightweight gypsum sand to the mixing tank, and stir and mix for 3-5 minutes to obtain a mixture of adhesive and aggregate.

[0193] Step 2: Pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air-entraining agent and 2 kg of heavy calcium carbonate to obtain an additive mixture;

[0194] Step 3: Add the additive mixture to the mixing tank and dry mix it with the adhesive and aggregate mixture for 3-5 minutes to obtain lightweight plaster.

[0195] The weight proportions of each material are as follows:

[0196] 46 parts building gypsum, 30 parts type II anhydrous gypsum, 4 parts cement, 20 parts lightweight gypsum sand, 0.1 parts thixotropic agent, 0.02 parts starch ether, 0.37 parts cellulose ether, 0.005 parts air-entraining agent, 5 parts activator, 0.006 parts polyacrylamide, and 0.5 parts retarder;

[0197] The thixotropic agent is bentonite; the air-entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonates, fatty alcohol sulfonates, saponins, protein salts, and petroleum sulfonate hydrochloric acid; the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate; and the retarder is a protein-based gypsum retarder. The specific properties of lightweight plastering gypsum are shown in Table 2.

[0198] The lightweight gypsum sand used in the lightweight plastering gypsum of Example 5 is prepared by the following method:

[0199] Based on the total mass of raw materials, the percentage content of raw materials in lightweight gypsum sand is as follows:

[0200] Parent material: Perlite filter aid with a particle size ≤ 0.102 mm, 9 parts;

[0201] Main ingredient 1: 30 parts desulfurized gypsum, 25 parts natural gypsum, 10 parts fluorogypsum, and 5 parts phosphogypsum;

[0202] Main material 2: 6 parts of silica-alumina minerals, 3 parts of kaolin minerals, 3 parts of aluminum oxide, and 1 part of dolomite;

[0203] Auxiliary materials: 2 parts quicklime;

[0204] pelletizing materials: 1 part clay, 2 parts bentonite, 1 part lignin cellulose;

[0205] Dispersant: 1 part sodium pyrophosphate, 1 part sodium hexametaphosphate;

[0206] Preparation methods include:

[0207] (1) Grinding: Main material 1, main material 2, auxiliary material, and pelletizing material are ground to 0.038mm respectively;

[0208] (2) Mud reaction: Add appropriate amount of water to the main material 1, main material 2, auxiliary material and pelletizing material and stir thoroughly in the mixing tank at a speed of 300 r / min for 10 min. At this time, the various materials are fully dispersed in the water to form mud liquid, and the various materials can fully contact and mix evenly.

[0209] (3) Dehydration: The mud slurry after the mud reaction is dehydrated by centrifugation, adsorption, and extrusion, and then dried at 250℃ to control the water content of the mud slurry to below 3% by mass, so as to obtain block material.

[0210] (4) Grinding: Grind the lumpy material into powder using a high-speed grinding mill at a speed of 3500 r / min to a particle size of 0.038 mm;

[0211] (5) Formation of mother ball: Pour the mother ball into the round pot granulator, and spray water to form granules A through the water spraying component of the granulator. Add 1 / 2 of the total weight of powder to granules A, and continue to form mother balls under the rapid rotation in the ball mill.

[0212] (6) Spherical formation: While the mother ball is being sprayed with water mist in the granulator, the remaining powder is added while spraying. As the ball mill rotates rapidly, the mother ball gradually grows larger to form the first spherical. At this point, no more water spraying is needed. Then, a dispersant is added to form the second spherical particles.

[0213] (7) Sieving: Remove the coarse particles from the second spherical particles obtained in step (6), leaving particles of 40-140 mesh for later use;

[0214] (8) Spherical shaping: The 40-140 mesh particles obtained in step (7) are spherically shaped again to form more rounded spheres. The sphericity of the rounded spheres after the shaping operation reaches more than 98%.

[0215] (9) Curing: Send the round sphere obtained in step (8) to the curing chamber for curing. The curing is carried out in two stages: water mist curing and dry curing.

[0216] (10) The spherical particles obtained in step (9) are sieved to obtain lightweight gypsum sand sample 4. The lightweight gypsum sand has a size of 0.106mm-0.425mm and an internal bulk density of 600kg / m³. 3 -700kg / m 3 All other indicators meet the requirements of GB / T 14684-2022 "Construction Sand".

[0217] The curing process in step (9) involves water mist curing for 6 days, with each water mist spraying lasting 4 hours, once a day, and the curing chamber temperature maintained at 25 degrees Celsius. Then, the product is moved to the next curing chamber for dry curing, which is maintained at room temperature for 14 days. The principle of the curing stage is to cause the gypsum in the raw materials to undergo a ceramicization reaction with the gypsum reactant (main material 2) to form ceramic spherical particles, thereby giving the product higher strength and water resistance. Specific performance details are shown in Table 1.

[0218] Example 6

[0219] A method for preparing a lightweight plastering gypsum includes the following steps:

[0220] Step 1: Add building gypsum, anhydrous gypsum II and lightweight gypsum sand to the mixing tank, and stir and mix for 3-5 minutes to obtain a mixture of adhesive and aggregate.

[0221] Step 2: Pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air-entraining agent and 2 kg of heavy calcium carbonate to obtain an additive mixture;

[0222] Step 3: Add the additive mixture to the mixing tank and dry mix it with the adhesive and aggregate mixture for 3-5 minutes to obtain lightweight plaster.

[0223] The weight proportions of each material are as follows:

[0224] 38 parts building gypsum, 30 parts type II anhydrous gypsum, 2 parts cement, 30 parts lightweight gypsum sand, 0.3 parts thixotropic agent, 0.02 parts starch ether, 0.29 parts cellulose ether, 0.005 parts air-entraining agent, 6 parts activator, 0.005 parts polyacrylamide, and 0.4 parts retarder;

[0225] The thixotropic agent is bentonite; the air-entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonates, fatty alcohol sulfonates, saponins, protein salts, and petroleum sulfonate hydrochloric acid; the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate; and the retarder is a protein-based gypsum retarder. The specific properties of lightweight plastering gypsum are shown in Table 2.

[0226] The lightweight gypsum sand used in the lightweight plastering gypsum of Example 6 is prepared by the following method:

[0227] Based on the total mass of raw materials, the percentage content of raw materials in lightweight gypsum sand is as follows:

[0228] Parent material: Perlite filter aid with a particle size ≤ 0.102 mm, 7 parts;

[0229] Main material 1: 30 parts desulfurized gypsum, 27 parts natural gypsum, 10 parts fluorogypsum, and 5 parts phosphogypsum;

[0230] Main material 2: 6 parts of silica-alumina minerals, 3 parts of kaolin minerals, 3 parts of aluminum oxide, and 1 part of dolomite;

[0231] Auxiliary materials: 2 parts quicklime;

[0232] pelletizing materials: 1 part clay, 2 parts bentonite, 1 part lignin cellulose;

[0233] Dispersant: 1 part sodium pyrophosphate, 1 part sodium hexametaphosphate;

[0234] Preparation methods include:

[0235] (1) Grinding: Main material 1, main material 2, auxiliary material and pelletizing material are ground to 0.039mm respectively;

[0236] (2) Mud reaction: Add appropriate amount of water to the main material 1, main material 2, auxiliary material and pelletizing material and stir thoroughly in the mixing tank at a speed of 265 r / min for 8 min. At this time, the various materials are fully dispersed in the water to form mud liquid, and the various materials can fully contact and mix evenly.

[0237] (3) Dehydration: The mud slurry after the mud reaction is dehydrated by centrifugation, adsorption, and extrusion, and then dried at 245℃ to control the water content of the mud slurry to below 3% by mass, so as to obtain block material.

[0238] (4) Grinding: Grind the lumpy material into powder using a high-speed grinding mill at a speed of 4000 r / min to a particle size of 0.039 mm;

[0239] (5) Formation of mother ball: Pour the mother ball into the round pot granulator, and spray water to form granules A through the water spraying component of the granulator. Add 1 / 3 of the total weight of powder to granules A, and continue to form mother balls under the rapid rotation in the ball mill.

[0240] (6) Spherical formation: While the mother ball is being sprayed with water mist in the granulator, the remaining powder is added while spraying. As the ball mill rotates rapidly, the mother ball gradually grows larger to form the first spherical. At this point, no more water spraying is needed. Then, a dispersant is added to form the second spherical particles.

[0241] (7) Sieving: Remove the coarse particles from the second spherical particles obtained in step (6), leaving particles of 40-140 mesh for later use;

[0242] (8) Spherical shaping: The 40-140 mesh particles obtained in step (7) are spherically shaped again to form more rounded spheres. The sphericity of the rounded spheres after the shaping operation reaches more than 98%.

[0243] (9) Curing: Send the round sphere obtained in step (8) to the curing chamber for curing. The curing is carried out in two stages: water mist curing and dry curing.

[0244] (10) The spherical particles obtained in step (9) are sieved to obtain lightweight gypsum sand sample 4. The lightweight gypsum sand has a size of 0.106mm-0.425mm and an internal bulk density of 600kg / m³. 3 -700kg / m 3 All other indicators meet the requirements of GB / T 14684-2022 "Construction Sand".

[0245] The curing process in step (9) involves water mist curing for 6 days, with each water mist spraying lasting 4 hours, once a day, and the curing chamber temperature maintained at 25 degrees Celsius. Then, the product is moved to the next curing chamber for dry curing, which is maintained at room temperature for 14 days. The principle of the curing stage is to cause the gypsum in the raw materials to undergo a ceramicization reaction with the gypsum reactant (main material 2) to form ceramic spherical particles, thereby giving the product higher strength and water resistance. Specific performance details are shown in Table 1.

[0246] Table 1 shows the performance test results of lightweight gypsum sand samples 1-4 according to GB / T 14684-2011 "Construction Sand".

[0247] Item Index Sample 1 Sample 2 Sample 3 Sample 4 Bulk density kg / m 3 ]]> ≤1000 620 635 680 650 Barrel pressure strength / MPa ≥2 4.1 4.7 5.0 4.9 Crushing rate / 28MPa ≤5％ 4.1 4.3 4.5 4.2 Water absorption rate / % ≤8％ 6.0 6.3 6.4 6.1 Sphericity / % ≥98 98 99 99 99 Softening coefficient ≥0.5 0.76 0.75 0.76 0.74

[0248] Table 2 shows the performance test results of the lightweight plastering gypsum in Examples 1-6 according to GB / T 28627-2022 "Plastering Gypsum" (lightweight plastering) and JC / T 2497-2018 "Mildew-resistant and Water-resistant Plastering Gypsum Mortar".

[0249]

[0250] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing lightweight plaster, characterized in that, The raw materials of the lightweight plastering gypsum include the following components in parts by weight: Building plaster: 30-50 parts; Type II anhydrous gypsum: 10-30 parts; 42.5 gray cement: 1 part - 5 parts; Lightweight gypsum sand: 30-50 parts; Thixotropic agent: 0.1 part to 1 part; Starch ether: 0.01-0.06 parts; Cellulose ether: 0.2-0.5 parts; Air-entraining agent: 0.005-0.01 parts; Water-retaining agent: 0.005 parts - 0.02 parts; Activator: 1-8 parts; and Retarder: 0.1-0.5 parts; The method for preparing the lightweight gypsum sand includes: The raw materials of the lightweight gypsum sand are as follows by weight: 5-10 parts of parent material particles, 65-80 parts of main material 1, 10-15 parts of main material 2, 2-5 parts of auxiliary materials, 3-5 parts of pelletizing material and 1-10 parts of dispersant; the sum of the above raw material amounts is 100 parts. Parent material particles: perlite filter aid with a particle size ≤ 0.102 mm; Main material 1: Any one or a mixture of any two or more of the following: natural gypsum, desulfurized gypsum, phosphogypsum, fluorogypsum, titanium gypsum, or other industrial by-product gypsum; Main material 2: Any one or a mixture of any two or more of the following: aluminate compounds, siliceous aluminate minerals, dolomite, soluble oxides, and aluminum oxide; Auxiliary materials: any one or a mixture of two of activated calcium and slaked lime; Pelletizing material: any one or a mixture of two or more of clay, lignin cellulose or bentonite, with a particle size ≤0.048mm; Dispersant: any one or a mixture of two of sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, and polycarboxylate; (1) Grinding: Main material 1, main material 2, auxiliary material and pelletizing material are ground to 0.037±0.005mm respectively; (2) Mud reaction: Add appropriate amount of water to the main material 1, main material 2, auxiliary material and pelletizing material and stir thoroughly in the mixing tank. The speed is 50-300 r / min and the stirring time is 5-10 min. At this time, the various materials are fully dispersed in the water to form mud liquid, and the various materials can fully contact and mix evenly. (3) Dehydration: The mud liquid after the mud reaction is dehydrated by centrifugation, adsorption, and extrusion, and then dried at 150-250℃ to control the water content of the mud liquid to be below 3% by mass, so as to obtain block material; (4) Grinding: The block material is ground by a high-speed grinding mill at a speed of 3000-6000 r / min to a powder of 0.037±0.005 mm; (5) Formation of mother ball: The mother ball is poured into a round pot granulator, and water is sprayed through the water spraying component of the granulator to form particles A. 1 / 3 to 1 / 2 of the total weight of the powder is added to particles A, and the mother ball is formed by continuing to rotate rapidly in the ball mill. (6) Spherical formation: While the mother ball is being sprayed with water mist in the granulator, the remaining powder is added while spraying. Under the rapid rotation of the ball mill, the mother ball gradually grows larger to form the first sphere. At this point, no more water spraying is needed. Then the dispersant is added to form the second spherical particles. (7) Sieving: Remove the coarse particles from the second spherical particles obtained in step (6), leaving particles of 40-140 mesh for later use; (8) Spherical shaping: The 40-140 mesh particles obtained in step (7) are spherically shaped again to form more rounded spheres. The sphericity of the rounded spheres after the shaping operation reaches more than 98%. (9) Curing: Send the round sphere obtained in step (8) to the curing chamber for curing. The curing is carried out in two stages: water mist curing and dry curing. (10) The spherical particles obtained in step (9) are sieved to obtain lightweight gypsum sand, wherein the lightweight gypsum sand has a size of 0.106mm-0.425mm and an internal bulk density of 600 kg / m³. 3 -700kg / m 3 .

2. The preparation method according to claim 1, characterized in that, The building gypsum is provided with the following mass percentages: hemihydrate ≥ 80%, dihydrate ≤ 4%, anhydrous ≤ 5%, based on the total mass of the building gypsum; the building gypsum has a 2-hour flexural strength ≥ 3.0 MPa, a 2-hour compressive strength ≥ 6.0 MPa, and a chloride ion content ≤ 600 mg / kg.

3. The preparation method according to claim 1 or 2, characterized in that, The type II anhydrous gypsum is required to meet the following requirements: a mass percentage of type II anhydrous gypsum ≥ 96%, a softening coefficient between 0.6 and 0.7, and a pH value between 12 and 13.

4. The preparation method according to claim 1 or 2, characterized in that, The 42.5 grey cement contains the following components by weight percentage: cement chemical composition CaO 60%-65%, SiO2 18%-19%, Al2O3 4%-5%, Fe2O3 2%-3%, MgO 2%-3% and SO3 3%-4%, based on the total weight of the 42.5 grey cement.

5. The preparation method according to claim 1 or 2, characterized in that, The thixotropic agent is a bentonite-based thixotropic agent.

6. The preparation method according to claim 1 or 2, characterized in that, The starch ether has a water content of 5%, a pH value between 6.0 and 8.0, and a viscosity of 400-1200 mPa·s.

7. The preparation method according to claim 1 or 2, characterized in that, The cellulose ether is hydroxypropyl methylcellulose with a viscosity of 40,000-150,000 mPa·s.

8. The preparation method according to claim 1 or 2, characterized in that, The air-entraining agent is one or more combinations of rosin resins, alkyl and alkyl aromatic sulfonic acids, fatty alcohol sulfonates, saponins, protein salts, and petroleum sulfonate hydrochloride.

9. The preparation method according to claim 1 or 2, characterized in that, The water-retaining agent is polyacrylamide.

10. The preparation method according to claim 1 or 2, characterized in that, The activator is one or more of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate.

11. The preparation method according to claim 1 or 2, characterized in that, The retarder is a protein-based gypsum retarder.

12. The preparation method according to claim 1 or 2, characterized in that, The preparation method of the lightweight plaster includes the following steps: Step 1: Add building gypsum, anhydrous gypsum II, and lightweight gypsum sand to a mixing tank, and stir and mix in the mixing tank for 3 min-5 min to obtain a mixture of adhesive and aggregate; Step 2: Pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air-entraining agent and heavy calcium carbonate to obtain a mixture of additives; Step 3: Add the additive mixture to the mixing tank and dry mix it with the adhesive and aggregate mixture for 3 min-5 min to obtain the lightweight plaster.

13. The preparation method according to claim 12, characterized in that, The maintenance in step (9) is as follows: the water mist maintenance lasts for 4-7 days, each water spray lasts for 4 hours, spray once a day, and the temperature of the maintenance chamber is 15-25 degrees Celsius; then move to the next maintenance chamber for dry maintenance, and maintain the room temperature for dry maintenance for 11-14 days.

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