Lightweight plastering gypsum with high coating rate and preparation method thereof

Abstract

The application provides a high-coating lightweight plastering gypsum and a preparation method thereof. The mechanical strength of the lightweight plastering gypsum prepared by mixing and stirring building gypsum, II anhydrous hard gypsum, self-prepared lightweight gypsum sand, vitrified microbeads and additives in a specific ratio can reach excellent performance such as a tensile bonding strength of 0.6-0.8 MPa under standard conditions and a tensile bonding strength of 0.28-0.4 MPa under humid conditions, which is greatly improved compared with the existing lightweight plastering gypsum with a tensile bonding strength of greater than or equal to 0.3 MPa.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building materials, in particular to a light-weight plastering gypsum with high coating rate and a preparation method thereof. BACKGROUND

[0002] Light-weight 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 as the cementitious material. Gypsum plastering can not only avoid the problems such as 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-weight plastering gypsum is smaller, which can not only reduce the load of the base body, but also reduce the energy consumption of the building due to the lower thermal conductivity. Under the form of national vigorous promotion of energy saving and emission reduction, light-weight plastering gypsum instead of traditional cement plastering will become a development trend, and the research on the preparation and performance of light-weight plastering gypsum has theoretical significance and use value for plastering materials.

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

[0004] CN115108796B discloses a light-weight plastering gypsum and a preparation method thereof. The product comprises the following raw materials in parts by weight: 700-760 parts of desulfurization gypsum, 135-170 parts of stone powder, 85-95 parts of vitrified microbeads, 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, and 1.0-2.5 parts of cellulose ether. The preparation method comprises the following steps: step 1) mixing the retarder, ramie fiber, straw fiber and cellulose ether uniformly to obtain a first mixture; step 2) mixing the desulfurization gypsum, vitrified microbeads and stone powder uniformly to obtain a second mixture; step 3) mixing the starch enzyme, thixotropic agent and retarder uniformly to obtain a third mixture; and step 4) mixing the first mixture, the second mixture and the third mixture uniformly to obtain a finished product. However, it still cannot meet the requirements of light-weight plastering gypsum with high coating rate, light weight and high strength.

[0005] CN115159939A discloses a lightweight plastering gypsum mortar preparation method, which solves the problem of high impurity content and low bonding strength of the prior art lightweight plastering gypsum mortar. 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, lightweight 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 product is improved, the mortar setting time and apparent density are reduced, by adding lightweight 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 is improved. But it still cannot meet the requirements of high coating rate, light weight and high strength of lightweight plastering gypsum.

[0006] In view of the high coating rate but low strength of the existing lightweight plastering gypsum, the problem of the present application is to develop a preparation method of lightweight plastering gypsum with high coating rate, low density, high strength, water resistance, mildew resistance and crack resistance. SUMMARY

[0007] In view of the defects of the prior art, the present application provides a lightweight plastering gypsum with high coating rate. By mixing and stirring specific proportions of building gypsum, type II anhydrous hard gypsum, self-made lightweight gypsum sand, vitrified microbeads and additives, the mechanical strength of the lightweight plastering gypsum can reach excellent performance such as standard tensile bonding strength of 0.6-0.8 MPa and moist tensile bonding strength of 0.28-0.4 MPa, which is greatly improved compared with the existing lightweight plastering gypsum with tensile bonding strength ≥0.3 MPa.

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

[0009] The present application provides a lightweight plastering gypsum with high coating rate, and the raw materials of the lightweight plastering gypsum with high coating rate comprise the following components by weight:

[0010] Building gypsum: 50-70 parts;

[0011] Type II anhydrous hard gypsum: 10-20 parts;

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

[0013] Lightweight gypsum sand: 10-45 parts;

[0014] Vitrified microbeads: 3-5 parts;

[0015] Thixotropic agent: 0.1-1 part;

[0016] Starch ether: 0.01-0.06 parts;

[0017] Cellulose ether: 0.2-0.5 parts;

[0018] Air entraining agent: 0.005-0.01 parts;

[0019] Water retaining agent: 0.005-0.02 parts;

[0020] Activator: 1-8 parts; and

[0021] Retarder: 0.1-0.5 parts.

[0022] Further, the building gypsum satisfies the mass percentage: hemihydrate phase ≥80%, dihydrate phase ≤4%, and anhydrite phase ≤5%. The 2h flexural strength of the building gypsum is ≥3.0 MPa, the 2h compressive strength is ≥6.0 MPa, and the chloride ion content is ≤600 mg / Kg.

[0023] Further, the type II anhydrite satisfies the mass percentage of type II anhydrite ≥96%, the softening coefficient is between 0.6-0.7, and the Ph value is between 12-13.

[0024] Further, the 42.5 grey cement contains the following ingredients 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. The burn vector of the 42.5 grey cement is ≤3%, NaOequi (representing alkaline oxides) is ≤1%, the 3d compressive strength is ≥3.5 MP, the 3d compressive strength is ≥17 MPa, the 28d flexural strength is ≥6.5 MPa, and the 28d compressive strength is ≥42.5 MPa.

[0025] Further, the lightweight gypsum sand has a particle size of 40-140 mesh, and the CaSO4 content is ≥90%.

[0026] Further, the vitrified microbead has a bulk density of 100-140 kg / m 3 , a particle size of 70-90 mesh, a volume water absorption of ≤45%, a closed pore rate of ≥80%, and a cylinder compressive strength of ≥200 KPa.

[0027] Further, the thixotropic agent is a bentonite type thixotropic agent.

[0028] Further, the starch ether has a water content of 5%, a pH value of 6.0-8.0, and a viscosity of 400-1200mpas.

[0029] Further, the cellulose ether is hydroxypropyl methylcellulose (HPMC) with a viscosity of 40000-150000mpas.

[0030] Further, the air entraining agent is one or more combinations of rosin resins, alkyl and alkyl aromatic sulfonic acids, fatty alcohol sulfonates, saponins, and protein salts, and petroleum sulfonates.

[0031] Further, the water-retaining thickening agent is polyacrylamide, which is used to increase the water retention, cohesiveness, and workability of the cement mortar.

[0032] Further, the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate.

[0033] Further, the retarder is a protein-based gypsum retarder.

[0034] The present application also provides a preparation method of the aforementioned lightweight plastering gypsum, comprising the following steps:

[0035] Step 1: adding building gypsum, type II anhydrous gypsum, lightweight gypsum sand, and vitrified microbeads into a stirring kettle, stirring and mixing in the stirring kettle for 3-5 minutes to obtain a glue material and aggregate mixture;

[0036] Step 2: pre-dispersing the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, and air entraining agent with heavy calcium to obtain an additive mixture;

[0037] Step 3: putting the additive mixture into the stirring kettle, and dry mixing and stirring the glue material and aggregate mixture for 3-5 minutes to obtain the lightweight plastering gypsum with high coating rate.

[0038] Further, in step 2, the heavy calcium is added in an amount of 2kg.

[0039] The early strength of the lightweight plastering gypsum of the present application during construction is provided by the building gypsum, and the late strength is provided by the type II anhydrous gypsum, and the reaction mechanism is as follows:

[0040] Reaction 1: CaSO4.0.5H2O+1.5H2O→CaSO4.2H2O+Q(19.2J / gSO3)

[0041] Reaction 2: mCaSO4(type II anhydrous gypsum)+salt(activator)+2H2O→salt.mCaSO4.nH2O(complex salt)

[0042] Salt.mCaSO4.nH2O+2mH2O→m(CaSO4.2H2O)+Salt.nH2O

[0043] Reaction 1 is the reaction of building gypsum (beta hemihydrate gypsum) with water to produce dihydrate gypsum, and reaction 2 is the reaction of type II anhydrite with an activator to generate unstable mCaSO4.nH2O (double salt), which is then decomposed into dihydrate gypsum, and repeatedly converted into dihydrate gypsum through the intermediate hydrate (mCaSO4.nH2O), thereby accelerating the dissolution of type II anhydrite.

[0044] In the present application, the vitrified microbeads and the lightweight gypsum sand serve as aggregates, playing the role of skeleton and filling in the lightweight plastering gypsum.

[0045] In the present application, the cellulose ether serves as a water-retaining thickening agent, mainly playing the role of water retention and viscosity increase.

[0046] In the present application, the thixotropic agent is bentonite, and its mechanism of action in the plastering gypsum is as follows: bentonite is an expansive clay material mainly composed of montmorillonite, which can absorb a large amount of water during the expansion process, up to 10 times its own weight, and can expand to 20-30 times its original volume. This will reduce the free water in the cement mortar, thereby reducing the fluidity of the mortar and rapidly losing its fluidity. The main component of bentonite is montmorillonite, which accounts for about 65% and has a columnar structure inside. After hydrolysis, it improves the stability of the cement mortar in lightweight plastering gypsum, and its unique sliding effect improves the sliding performance and pumpability of the mortar to some extent.

[0047] In the present application, the air entraining agent has the following mechanism of action in the lightweight plastering gypsum: the air entraining agent produces foam in water, forming a gas-liquid dispersion system, and the air entraining agent is adsorbed on the gas-liquid interface and reduces the surface tension. The addition of the air entraining agent significantly reduces the surface tension of the solution, making the bubbles fine, uniform, and regular in shape, and spherical. The fine aggregate particles in the cement mortar support the bubbles like a four-dimensional network, helping to stabilize the bubbles, and when used in appropriate amounts, have no significant effect on the strength of the hardened mortar, and can greatly improve the workability and durability of the cement mortar.

[0048] In the present application, the mechanism of action of polyacrylamide on the hydration of building gypsum is as follows: on the one hand, it interacts with Ca 2+ in building gypsum to form compounds and fill the gaps between the dihydrate gypsum crystals produced by the hydration of building gypsum; on the other hand, the polyacrylamide molecules wrap the desulfurized building gypsum particles, thereby hindering the hydration reaction with water, thereby improving the water retention, cohesiveness, and workability of the product.

[0049] In the present application, the mechanism of the protein retarder is mainly to inhibit the rate of generating crystalline germ, 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.

[0050] Further, the preparation method of the light gypsum sand comprises:

[0051] The raw material percentage content of the light gypsum sand is: 5-10 parts of matrix particles, 65-80 parts of main material 1, 10-15 parts of main material 2, 2-5 parts of auxiliary material, 3-5 parts of balling material, and the balance is a dispersing agent, based on the total mass of the raw materials;

[0052] The matrix particles are perlite filter aids with a particle size of ≤0.102 mm;

[0053] The main material 1 is any one or a mixture of two or more of natural gypsum, desulfurization gypsum, phosphogypsum, fluorogypsum, titanium gypsum, or other industrial by-product gypsum;

[0054] The main material 2 is any one or a mixture of two or more of aluminate compounds, silico-alumina minerals, kaolin minerals, dolomite, soluble oxides, and aluminum oxide;

[0055] The auxiliary material is any one or a mixture of two of active calcium and slaked lime;

[0056] The balling material is any one or a mixture of two or more of clay, lignin cellulose, or bentonite, all with a particle size of ≤0.048 mm;

[0057] The dispersing agent is any one or a mixture of two of sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, or polycarboxylate;

[0058] The preparation method comprises:

[0059] (1) Grinding: grinding the main material 1, the main material 2, the auxiliary material, and the balling material to 0.037±0.005 mm respectively;

[0060] (2) Mud reaction: adding the main material 1, the main material 2, the auxiliary material, and the balling material into a stirring kettle with an appropriate amount of water, fully stirring at a speed of 50-300 r / min for 5-10 min, at this time, the various materials are fully dispersed in the water to form a mud liquid, and the various materials can fully contact and mix uniformly;

[0061] (3) Dewatering: after the mud reaction, the mud liquid is dewatered by centrifugation, adsorption, and extrusion, and then dried at 150-250℃ to control the water content of the mud liquid to less than 3% by mass percentage, to obtain a block material;

[0062] (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;

[0063] (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.

[0064] (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.

[0065] (7) Sieving: Remove the coarse particles from the second spherical particles obtained in step (6), leaving particles of 40-140 mesh for later use;

[0066] (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%.

[0067] (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.

[0068] (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".

[0069] Furthermore, in step (6), the particle size of the first sphere is 20-140 mesh.

[0070] Furthermore, in step (6), particles with a diameter ≥ 0.425 mm are removed.

[0071] 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.

[0072] The beneficial effects of this invention are as follows:

[0073] (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 a small amount of vitrified microspheres and 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 580 kg / m³. 3 -650Kg / m 3 Between these, the density is extremely light.

[0074] (2) The present invention incorporates II anhydrous gypsum and adds an activator, which ensures the high strength of the high coating rate lightweight plaster plaster in the later stage. On the other hand, the incorporation of II anhydrous gypsum and gypsum sand can improve the water resistance and mildew resistance of the product.

[0075] (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.

[0076] (4) This invention uses self-developed gypsum sand, combined with building gypsum, anhydrous gypsum II, and vitrified microspheres to produce a lightweight plastering gypsum. This gypsum exhibits excellent performance in terms of mechanical strength, bulk density, mildew resistance, coating rate, and crack resistance. Specifically, the coating rate is between 160-170%, and the bulk density is 580-630 kg / m³. 3The tensile bonding strength under standard state is 0.6-0.8 MPa, and the tensile bonding strength under wet state is 0.28-0.4 MPa.

[0077] (5) The application produces light plastering gypsum by using industrial waste, realizes waste utilization, and replaces building sand with gypsum sand, so as to solve the shortage of sand resources, reduce the cost by about half compared with building sand, and has high economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0078] Figure 1 The preparation process flow chart of the high-coating-rate light plastering gypsum of the application is shown. DETAILED DESCRIPTION

[0079] The preferred embodiments of the application will be described in more detail below. Although the preferred embodiments of the application are described below, it should be understood that the application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the application more thorough and complete, and to fully convey the scope of the application to those skilled in the art.

[0080] Example 1

[0081] A high-coating-rate light plastering gypsum, comprising 50 parts of building gypsum, 19 parts of type II anhydrous hard gypsum, 2 parts of 42.5 cement, 4 parts of vitrified microbeads, 25 parts of light gypsum sand, 0.2 parts of thixotropic agent, 0.3 parts of cellulose ether, 0.01 parts of starch ether, 0.01 parts of air entraining agent, 3 parts of activator, 0.005 parts of polyacrylamide, and 0.4 parts of retarder.

[0082] The preparation method comprises the following steps:

[0083] Step 1: adding building gypsum, type II anhydrous hard gypsum, light gypsum sand and vitrified microbeads into a stirring kettle, stirring and mixing in the stirring kettle for 3-5 min to obtain a glue material and aggregate mixture;

[0084] Step 2: pre-dispersing the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide and air entraining agent with 2 kg of heavy calcium to obtain an additive mixture;

[0085] Step 3: putting the additive mixture into the stirring kettle, and dry mixing and stirring the glue material and aggregate mixture for 3-5 min to obtain the high-coating-rate light plastering gypsum.

[0086] The weight parts of each material are as follows:

[0087] Building gypsum 50 parts, anhydrite type II 19 parts, 42.5 cement 2 parts, vitrified microbead 4 parts, lightweight gypsum sand 25 parts, thixotropic agent 0.2 parts, cellulose ether 0.3 parts, starch ether 0.01 parts, air entraining agent 0.01 parts, activator 3 parts, polyacrylamide 0.005 parts, retarder 0.4 parts;

[0088] The thixotropic agent is bentonite; the air entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonic acid, fatty alcohol sulfonate, saponin, and protein salt, and petroleum sulfonate; 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 the lightweight plastering gypsum are shown in Table 2.

[0089] The preparation method of the lightweight gypsum sand used in the lightweight plastering gypsum of Example 1 is as follows:

[0090] The percentage content of the raw materials of the lightweight gypsum sand is as follows based on the total mass of the raw materials:

[0091] Mother particles: perlite filter aid with a particle size of ≤0.102 mm, 5 parts;

[0092] Main material 1: desulfurization gypsum 32 parts, natural gypsum 30 parts, and fluorine gypsum 5 parts;

[0093] Main material 2: aluminate compound 5 parts and kaolin mineral 5 parts;

[0094] Auxiliary material: slaked lime 3 parts and active calcium 2 parts;

[0095] Ball-forming material: clay 1 part, bentonite 2 parts, and lignin cellulose 1 part;

[0096] Dispersant: sodium pyrophosphate 3 parts, polycarboxylate 3 parts, and sodium tripolyphosphate 3 parts;

[0097] The preparation method includes:

[0098] (1) Grinding: the main material 1, the main material 2, the auxiliary material, and the ball-forming material are respectively ground to 0.037±0.005 mm;

[0099] (2) Mud reaction: the main material 1, the main material 2, the auxiliary material, and the ball-forming material are added into a stirring kettle with an appropriate amount of water for full stirring at a speed of 300 r / min for 7 min. At this time, the various materials are fully dispersed in the water to form a mud liquid, and the various materials can fully contact and mix uniformly;

[0100] (3) Dewatering: the mud liquid after the mud reaction is dewatered by centrifugation, adsorption, and extrusion, and then dried at 200℃ to control the water content of the mud liquid to be less than 3% by mass to obtain a block material;

[0101] (4) Powdering: the blocky material is ground to a powder through a high-speed grinding machine at a speed of 3000 r / min, and the powder is ground to 0.036 mm;

[0102] (5) Formation of parent ball: the parent particles are poured into a round pan granulator, and water spraying is realized through the water spraying assembly of the granulator to form granules A, and 1 / 3 of the total weight of the powder is added to the granules A, and the parent ball is formed under the condition of continuous rapid rotation of the ball mill;

[0103] (6) Formation of ball: the parent ball continues to be sprayed with water in the granulator, and the remaining powder is added while spraying, and the parent ball gradually becomes larger to form the first ball under the condition of rapid rotation of the ball mill, and at this time, water is not sprayed, and then a dispersing agent is added to form the second ball;

[0104] (7) Screening: the second ball obtained in step (6) is screened to remove coarse particles, and the particles with a particle size of 40-140 are reserved for use;

[0105] (8) Ball shaping: the particles with a particle size of 40-140 obtained in step (7) are subjected to ball shaping operation again to form more round balls, and the roundness of the round balls after the shaping operation reaches more than 98%;

[0106] (9) Curing: the round balls obtained in step (8) are sent to a curing bin for curing, and water spraying curing and dry curing are adopted in two stages for curing;

[0107] (10) The ball particles obtained in step (9) are screened to obtain a light gypsum sand sample 1, and the light gypsum sand has a particle size of 0.106-0.425 mm and an internal bulk density of 600 kg / m 3 -700 kg / m 3 , and other indicators meet the requirements of GB / T 14684-2022 “Construction sand”.

[0108] The curing in step (9) is, wherein the water spraying curing lasts for 4-7 days, each time for 4 hours, once a day, and the temperature of the curing bin is 15-25 degrees Celsius; the dry curing is carried out in the next curing bin, and the room temperature is maintained for 11-14 days. The principle of the curing stage is that the gypsum in the raw material reacts with the gypsum reaction agent (main material 2) to form ceramic ball particles, so that the product has high strength and water resistance, and the specific performance is shown in Table 1.

[0109] Example 2

[0110] A high-coating lightweight plastering gypsum, comprising building gypsum 60 parts, type II anhydrous hard gypsum 12 parts, 42.5 gray cement 3 parts, vitrified microbead 5 parts, lightweight gypsum sand 20 parts, thixotropic agent 0.1 part, starch ether 0.02 part, cellulose ether 0.4 part, air entraining agent 0.006 part, activator 1 part, polyacrylamide 0.007 part, retarder 0.3 part;

[0111] The preparation method comprises the following steps:

[0112] Step 1: adding building gypsum, type II anhydrous hard gypsum, lightweight gypsum sand and vitrified microbead in a stirred kettle, stirring and mixing in the stirred kettle for 3-5 minutes to obtain a glue material and aggregate mixture;

[0113] Step 2: pre-dispersing the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide and air entraining agent with 2 kg heavy calcium to obtain an additive mixture;

[0114] Step 3: putting the additive mixture into the stirred kettle, dry mixing and stirring the glue material and aggregate mixture for 3-5 minutes to obtain the high-coating lightweight plastering gypsum.

[0115] The weight parts of each material are as follows:

[0116] Building gypsum 60 parts, type II anhydrous hard gypsum 12 parts, 42.5 gray cement 3 parts, vitrified microbead 5 parts, lightweight gypsum sand 20 parts, thixotropic agent 0.1 part, starch ether 0.02 part, cellulose ether 0.4 part, air entraining agent 0.006 part, activator 1 part, polyacrylamide 0.007 part, retarder 0.3 part;

[0117] The thixotropic agent is bentonite; the air entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonic acid, fatty alcohol sulfonate, saponin and protein salt, petroleum sulfonate acid; the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, sodium bisulfate; the retarder is a protein gypsum retarder. The specific performance of the lightweight plastering gypsum is shown in Table 2.

[0118] The preparation method of the lightweight gypsum sand used in the lightweight plastering gypsum of Example 2 is as follows:

[0119] The percentage content of the raw materials of the lightweight gypsum sand is as follows based on the total mass of the raw materials as a percentage:

[0120] Mother particle: perlite filter aid with a particle size of ≤0.102 mm, 7 parts;

[0121] Main material 1: desulfurization gypsum 34 parts, natural gypsum 21 parts, titanium gypsum 2 parts and phosphor gypsum 3 parts;

[0122] Main material 2: soluble oxide 5 parts, aluminum oxide 10 parts and dolomite 1 part;

[0123] Auxiliary material: slaked lime 3 parts;

[0124] Ball forming material: clay 1 part, bentonite 1 part and lignin cellulose 2 parts;

[0125] Dispersing agent: sodium pyrophosphate 2 parts, sodium hexametaphosphate 3 parts and sodium tripolyphosphate 5 parts;

[0126] The preparation method comprises:

[0127] (1) Grinding: the main material 1, the main material 2, the auxiliary material, and the ball forming material are respectively ground to 0.037mm;

[0128] (2) Mud reaction: the main material 1, the main material 2, the auxiliary material, and the ball forming material are added into a stirring kettle with an appropriate amount of water for sufficient stirring at a speed of 150r / min for 5min, at which time the various materials are fully dispersed in the water to form a mud liquid, and the various materials can fully contact and mix uniformly;

[0129] (3) Dewatering: the mud liquid after mud reaction is dewatered by centrifugation, adsorption and extrusion, and then dried at 150℃ to control the water content of the mud liquid to less than 3% by mass percentage, to obtain a blocky material;

[0130] (4) Powdering: the blocky material is ground by a high-speed grinding machine at a speed of 4000r / min to a powder of 0.037mm;

[0131] (5) Mother ball formation: the mother particles are poured into a round pan granulator, and water is sprayed to form granules A by the water spray assembly of the granulator; 1 / 2 of the total weight of the powder is added to the granules A, and the mother ball is formed under the condition of rapid rotation of the ball mill;

[0132] (6) Ball formation: the mother ball continues to be sprayed with water in the granulator, and the remaining powder is added while spraying, and the mother ball gradually becomes larger to form the first ball under the condition of rapid rotation of the ball mill, and then the dispersing agent is added to form the second ball;

[0133] (7) Screening: the second ball particles obtained in step (6) are screened to remove coarse particles, and the particles with a particle size of 40-140 are reserved for use;

[0134] (8) Ball shaping: the particles with a particle size of 40-140 obtained in step (7) are subjected to ball shaping operation again to form more round balls, and the roundness of the round balls after shaping operation reaches more than 98%;

[0135] (9) Curing: send the round ball obtained in step (8) to the curing bin for curing, and curing is carried out in two stages of water spray curing and dry curing;

[0136] (10) Screen the ball particles obtained in step (9) to obtain a lightweight gypsum sand sample 2, the lightweight gypsum sand has a specification of 0.106mm-0.425mm and an internal bulk density of 600kg / m 3 -700kg / m 3 , and other indicators meet the requirements of GB / T 14684-2022 "Construction sand".

[0137] The curing in step (9) is, wherein the water spray curing lasts for 7 days, each time of water spraying lasts for 4 hours, the curing bin temperature is 25 degrees Celsius, and the dry curing is carried out in the next curing bin for 12 days at room temperature. The principle of the curing stage is that the ceramicization reaction of the gypsum in the raw material and the gypsum reaction agent (main material 2) forms ceramic ball particles, so that the product has high strength and water resistance, and the specific performance is shown in Table 1.

[0138] Example 3

[0139] A lightweight plastering gypsum with high coating rate, comprising 65 parts of building gypsum, 10 parts of type II anhydrous hard gypsum, 2 parts of cement, 3 parts of vitrified microbeads, 20 parts of lightweight gypsum sand, 0.15 parts of thixotropic agent, 0.01 parts of starch ether, 0.35 parts of cellulose ether, 0.007 parts of air entraining agent, 1 part of activator, 0.005 parts of polyacrylamide, and 0.35 parts of retarder;

[0140] The preparation method comprises the following steps:

[0141] Step 1: add building gypsum, type II anhydrous hard gypsum, lightweight gypsum sand and vitrified microbeads into a stirring kettle, and stir and mix in the stirring kettle for 3min-5min to obtain a glue material and aggregate mixture;

[0142] Step 2: pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide and air entraining agent with 2kg of heavy calcium to obtain an additive mixture;

[0143] Step 3: put the additive mixture into the stirring kettle, and dry mix and stir the glue material and aggregate mixture for 3min-5min to obtain the lightweight plastering gypsum with high coating rate.

[0144] The weight parts of each material are as follows:

[0145] Building gypsum 65 parts, type II anhydrous gypsum 10 parts, cement 2 parts, vitrified microbead 3 parts, lightweight gypsum sand 20 parts, thixotropic agent 0.15 parts, starch ether 0.01 parts, cellulose ether 0.35 parts, air entraining agent 0.007 parts, activator 1 part, polyacrylamide 0.005 parts, retarder 0.35 parts;

[0146] The thixotropic agent is bentonite; the air entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonic acid, fatty alcohol sulfonate, saponin, and protein salt, and petroleum sulfonate 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 the lightweight plastering gypsum are shown in Table 2.

[0147] The preparation method of the lightweight gypsum sand used in the lightweight plastering gypsum of Example 3 is as follows:

[0148] The percentage content of the raw materials of the lightweight gypsum sand is as follows based on the total mass of the raw materials:

[0149] Mother particles: perlite filter aid with a particle size of ≤0.102 mm, 6 parts;

[0150] Main material 1: desulfurization gypsum 34 parts, natural gypsum 24 parts, fluorine gypsum 10 parts, and phosphor gypsum 5 parts;

[0151] Main material 2: silico-aluminate mineral 5 parts, kaolin mineral 3 parts, aluminum oxide 2 parts, and dolomite 1 part;

[0152] Auxiliary material: slaked lime 2 parts;

[0153] Ball-forming material: clay 1 part, bentonite 2 parts, and lignin cellulose 2 parts;

[0154] Dispersant: sodium pyrophosphate 2 parts and sodium hexametaphosphate 1 part;

[0155] The preparation method includes:

[0156] (1) Grinding: grinding main material 1, main material 2, auxiliary material, and ball-forming material to 0.040 mm respectively;

[0157] (2) Mud reaction: adding main material 1, main material 2, auxiliary material, and ball-forming material into a stirring kettle with an appropriate amount of water to fully stir, at a speed of 300 r / min and for 8 min. At this time, the various materials are fully dispersed in the water to form a mud liquid, and the various materials can fully contact and mix uniformly;

[0158] (3) Dewatering: the mud liquid after the mud reaction is dewatered by centrifugation, adsorption, and extrusion, and then dried at 200°C to control the water content of the mud liquid to less than 3% by mass to obtain a block material;

[0159] (4) Powdering: the blocky material is ground through a high-speed grinding machine at a speed of 3000 r / min to a powder of 0.040 mm;

[0160] (5) Formation of mother spheres: the mother particles are poured into a round pan granulator, water spraying is realized through the water spraying assembly of the granulator to form granules A, 1 / 3 of the total weight of the powder is added to the granules A, and the mother spheres are formed under the condition of continuous rapid rotation of the ball mill;

[0161] (6) Sphere formation: the mother spheres continue to be sprayed with water in the granulator, the remaining powder is added while spraying, the mother spheres gradually grow into first spheres under the condition of rapid rotation of the ball mill, at this time, no water is sprayed, then a dispersing agent is added to form second sphere particles;

[0162] (7) Screening: the second sphere particles obtained in step (6) are screened to remove coarse particles, and particles with a particle size of 40-140 μm are reserved for use;

[0163] (8) Sphere shaping: the particles with a particle size of 40-140 μm obtained in step (7) are subjected to sphere shaping operation again to form more round spheres, and the roundness of the round spheres after the shaping operation reaches more than 98%;

[0164] (9) Curing: the round spheres obtained in step (8) are sent to a curing bin for curing, and the curing is carried out in two stages of water spraying curing and dry curing;

[0165] (10) The sphere particles obtained in step (9) are screened to obtain a light gypsum sand sample 3, the light gypsum sand has a particle size of 0.106 mm-0.425 mm and an internal bulk density of 600 kg / m 3 -700 kg / m 3 , and other indicators meet the requirements of GB / T 14684-2022 “Construction sand”.

[0166] The curing in step (9) is carried out for 5 days, each time for 4 hours, once a day, and the temperature of the curing bin is 20 degrees Celsius; the next curing bin is turned to carry out dry curing, and the room temperature is maintained for 14 days. The principle of the curing stage is that the gypsum in the raw material reacts with the gypsum reaction agent (main material 2) to form ceramic sphere particles, so that the product has high strength and water resistance, and the specific performance is shown in Table 1.

[0167] Example 4

[0168] A high-coating lightweight plastering gypsum, comprising 70 parts of building gypsum, 10 parts of type II anhydrous hard gypsum, 1 part of cement, 4 parts of vitrified microbeads, 14 parts of lightweight gypsum sand, 0.3 parts of thixotropic agent, 0.01 parts of starch ether, 0.45 parts of cellulose ether, 0.005 parts of air entraining agent, 2 parts of activator, 0.006 parts of polyacrylamide, and 0.65 parts of retarder;

[0169] The preparation method comprises the following steps:

[0170] Step 1: adding building gypsum, type II anhydrous hard gypsum, lightweight gypsum sand and vitrified microbeads into a stirred tank, stirring and mixing in the stirred tank for 3-5 minutes to obtain a mixture of binder and aggregate;

[0171] Step 2: pre-dispersing the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide and air entraining agent with 2 kg of heavy calcium to obtain an additive mixture;

[0172] Step 3: putting the additive mixture into the stirred tank, and dry mixing and stirring the additive mixture with the mixture of binder and aggregate for 3-5 minutes to obtain the high-coating lightweight plastering gypsum.

[0173] The weight parts of each material are as follows:

[0174] The high-coating lightweight plastering gypsum comprises 70 parts of building gypsum, 10 parts of type II anhydrous hard gypsum, 1 part of cement, 4 parts of vitrified microbeads, 14 parts of lightweight gypsum sand, 0.3 parts of thixotropic agent, 0.01 parts of starch ether, 0.45 parts of cellulose ether, 0.005 parts of air entraining agent, 2 parts of activator, 0.006 parts of polyacrylamide, and 0.65 parts of retarder;

[0175] The thixotropic agent is bentonite; the air entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonic acid, fatty alcohol sulfonate, saponin, protein salt and petroleum sulfonate; the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, sodium bisulfate; the retarder is a protein-based gypsum retarder. The specific performance of the lightweight plastering gypsum is shown in Table 2.

[0176] The preparation method of the lightweight gypsum sand used in the lightweight plastering gypsum of Example 4 is as follows:

[0177] The percentage content of the raw materials of the lightweight gypsum sand is as follows based on the total mass of the raw materials:

[0178] Mother material: perlite filter aid with a particle size of ≤0.102 mm, 10 parts;

[0179] Main material 1: desulfurization gypsum 30 parts, natural gypsum 24 parts, fluorine gypsum 10 parts, and phosphorus gypsum 5 parts;

[0180] Main material 2: siliceous mineral 6 parts, kaolin mineral 3 parts, aluminum oxide 3 parts, dolomite 1 part;

[0181] Auxiliary material: slaked lime 2 parts;

[0182] Ball forming material: clay 1 part, bentonite 2 parts, lignin cellulose 1 part;

[0183] Dispersing agent: sodium pyrophosphate 1 part, sodium hexametaphosphate 1 part;

[0184] The preparation method comprises:

[0185] (1) Grinding: the main material 1, main material 2, auxiliary material, and ball forming material are respectively ground to 0.041mm;

[0186] (2) Mud reaction: the main material 1, main material 2, auxiliary material, and ball forming material are added into the stirring kettle with appropriate amount of water for sufficient stirring, the rotating speed is 260r / min, and the stirring time is 7min. At this time, various materials are fully dispersed in water to form mud liquid, and various materials can fully contact and mix uniformly;

[0187] (3) Dehydration: the mud liquid after mud reaction is dehydrated by centrifugation, adsorption, and extrusion, and then dried at 250℃ to control the water content of the mud liquid below 3% by mass fraction, to obtain blocky material;

[0188] (4) Powdering: the blocky material is ground by a high-speed grinding machine at a rotating speed of 3000r / min to obtain a powder with a particle size of 0.041mm;

[0189] (5) Mother ball formation: the mother particles are poured into a round pan granulator, water is sprayed through the water spray assembly of the granulator to form granules A, and 1 / 3 of the total weight of the powder is added to the granules A. Continue to rotate in the ball mill to form the mother ball;

[0190] (6) Ball formation: the mother ball continues to be sprayed in the granulator, and the remaining powder is added while spraying. Under the condition of rapid rotation of the ball mill, the mother ball gradually increases to form the first ball. At this time, no water is needed to be sprayed, and then the dispersing agent is added to form the second ball;

[0191] (7) Screening: the second ball particles obtained in step (6) are screened to remove coarse particles, and the particles with a particle size of 40-140 are reserved for use;

[0192] (8) Ball shaping: the particles with a particle size of 40-140 obtained in step (7) are subjected to ball shaping operation again to form more round balls. The roundness of the round balls after shaping operation reaches more than 98%;

[0193] (9) Curing: send the round ball obtained in step (8) to a curing bin for curing, and curing is carried out in two stages of water mist curing and dry curing;

[0194] (10) Screen the ball particles obtained in step (9) to obtain a lightweight gypsum sand sample 4, the lightweight gypsum sand has a specification of 0.106mm-0.425mm and an internal bulk density of 600kg / m 3 -700kg / m 3 , and other indexes meet the requirements of GB / T 14684-2022 "Construction sand".

[0195] The curing in step (9) is, wherein the water mist curing lasts for 6 days, each time of water spraying lasts for 4 hours, the curing bin temperature is 15 degrees Celsius, and the dry curing is carried out in the next curing bin for 14 days at room temperature. The principle of the curing stage is that the ceramicization reaction of the gypsum in the raw material and the gypsum reaction agent (main material 2) forms ceramic ball particles, so that the product has high strength and water resistance, and the specific performance is shown in Table 1.

[0196] Example 5

[0197] A lightweight plastering gypsum with high coating rate, comprising 66 parts of building gypsum, 15 parts of type II anhydrous hard gypsum, 2 parts of cement, 3 parts of vitrified microbeads, 13 parts of lightweight gypsum sand, 0.1 part of thixotropic agent, 0.02 part of starch ether, 0.36 part of cellulose ether, 0.005 part of air entraining agent, 2.5 parts of activator, 0.006 part of polyacrylamide, and 0.5 part of retarder;

[0198] The preparation method comprises the following steps:

[0199] Step 1: add building gypsum, type II anhydrous hard gypsum, lightweight gypsum sand and vitrified microbeads into a stirring kettle, and stir and mix in the stirring kettle for 3min-5min to obtain a glue material and aggregate mixture;

[0200] Step 2: pre-disperse the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide and air entraining agent with 2kg of heavy calcium to obtain an additive mixture;

[0201] Step 3: put the additive mixture into the stirring kettle, and dry mix and stir the glue material and aggregate mixture for 3min-5min to obtain the lightweight plastering gypsum with high coating rate.

[0202] The weight parts of each material are as follows:

[0203] Building gypsum 66 parts, anhydrite type II 15 parts, cement 2 parts, vitrified microbead 3 parts, lightweight gypsum sand 13 parts, thixotropic agent 0.1 part, starch ether 0.02 part, cellulose ether 0.36 part, air entraining agent 0.005 part, activator 2.5 parts, polyacrylamide 0.006 part, retarder 0.5 part;

[0204] The thixotropic agent is bentonite; the air entraining agent is one or more of combinations of rosin resin, alkyl and alkyl aromatic sulfonic acid, fatty alcohol sulfonate, saponin, and protein salt, petroleum sulfonate; the activator is one or more of combinations of potassium sulfate, KAl(SO4)2, calcined alum, sodium bisulfate; the retarder is protein gypsum retarder. The specific performance of the lightweight plastering gypsum is shown in Table 2.

[0205] The preparation method of the lightweight gypsum sand used in the lightweight plastering gypsum of Example 5 is as follows:

[0206] The percentage content of the raw materials of the lightweight gypsum sand is as follows based on the total mass of the raw materials:

[0207] Mother particle: perlite filter aid with a particle size of ≤0.102 mm, 9 parts;

[0208] Main material 1: desulfurization gypsum 30 parts, natural gypsum 25 parts, fluorine gypsum 10 parts, phosphor gypsum 5 parts;

[0209] Main material 2: silico-aluminate mineral 6 parts, kaolin mineral 3 parts, aluminum oxide 3 parts, dolomite 1 part;

[0210] Auxiliary material: slaked lime 2 parts;

[0211] Ball-forming material: clay 1 part, bentonite 2 parts, lignin cellulose 1 part;

[0212] Dispersing agent: sodium pyrophosphate 1 part, sodium hexametaphosphate 1 part;

[0213] The preparation method includes:

[0214] (1) Grinding: the main material 1, the main material 2, the auxiliary material, and the ball-forming material are respectively ground to 0.038 mm;

[0215] (2) Mud reaction: the main material 1, the main material 2, the auxiliary material, and the ball-forming material are added into a stirring kettle with an appropriate amount of water for full stirring at a speed of 300 r / min for 10 min. At this time, the various materials are fully dispersed in the water to form a mud liquid, and the various materials can fully contact and mix uniformly;

[0216] (3) Dewatering: the mud liquid after the mud reaction is dewatered by centrifugation, adsorption, and extrusion, and then dried at 250℃ to control the water content of the mud liquid to be less than 3% by mass to obtain a block material;

[0217] (4) Powdering: the blocky material is ground through a high-speed grinding machine at a speed of 3500 r / min to a powder of 0.038 mm;

[0218] (5) Formation of mother spheres: the mother particles are poured into a round pan granulator, water spraying is realized through the water spraying assembly of the granulator to form granules A, and the total weight of 1 / 2 of the powder is added to the granules A, and the mother spheres are formed under the condition of continuous rapid rotation of the ball mill;

[0219] (6) Sphere formation: the mother spheres continue to be sprayed with water in the granulator, and the remaining powder is added while spraying, and the mother spheres gradually become larger to form the first spheres under the condition of rapid rotation of the ball mill, and then the dispersing agent is added to form the second sphere particles;

[0220] (7) Screening: the second sphere particles obtained in step (6) are screened to remove coarse particles, and the particles with a particle size of 40-140 are reserved for use;

[0221] (8) Sphere shaping: the particles with a particle size of 40-140 obtained in step (7) are subjected to sphere shaping operation again to form more round spheres, and the roundness of the round spheres after the shaping operation reaches more than 98%;

[0222] (9) Curing: the round spheres obtained in step (8) are sent to a curing bin for curing, and the curing is carried out in two stages of water spraying curing and dry curing;

[0223] (10) The sphere particles obtained in step (9) are screened to obtain a light gypsum sand sample 4, and the light gypsum sand has a particle size of 0.106 mm-0.425 mm and an internal bulk density of 600 kg / m 3 -700 kg / m 3 , and other indicators meet the requirements of GB / T 14684-2022 "Construction sand".

[0224] The curing in step (9) is carried out for 6 days, each time for 4 hours, once a day, and the temperature of the curing bin is 25 degrees Celsius; the next curing bin is turned to carry out dry curing, and the room temperature is maintained for 14 days. The principle of the curing stage is that the gypsum in the raw material reacts with the gypsum reaction agent (main material 2) to form ceramic sphere particles, so that the product has high strength and water resistance, and the specific performance is shown in Table 1.

[0225] Example 6

[0226] A high-coating lightweight plastering gypsum, comprising building gypsum 58 parts, type II anhydrous hard gypsum 15 parts, cement 2 parts, vitrified microbead 5 parts, lightweight gypsum sand 20 parts, thixotropic agent 0.3 parts, starch ether 0.02 parts, cellulose ether 0.5 parts, air entraining agent 0.005 parts, activator 1 part, polyacrylamide 0.005 parts, retarder 0.4 parts;

[0227] The preparation method comprises the following steps:

[0228] Step 1: adding building gypsum, type II anhydrous hard gypsum, lightweight gypsum sand and vitrified microbead in a stirring kettle, stirring and mixing in the stirring kettle for 3-5 minutes to obtain a glue material and aggregate mixture;

[0229] Step 2: dispersing the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air entraining agent with 2 kg heavy calcium to obtain an additive mixture;

[0230] Step 3: putting the additive mixture into the stirring kettle, dry mixing and stirring the glue material and aggregate mixture for 3-5 minutes to obtain the high-coating lightweight plastering gypsum.

[0231] The weight parts of each material are as follows:

[0232] A high-coating lightweight plastering gypsum, comprising building gypsum 58 parts, type II anhydrous hard gypsum 15 parts, cement 2 parts, vitrified microbead 5 parts, lightweight gypsum sand 20 parts, thixotropic agent 0.3 parts, starch ether 0.02 parts, cellulose ether 0.5 parts, air entraining agent 0.005 parts, activator 1 part, polyacrylamide 0.005 parts, retarder 0.4 parts;

[0233] The thixotropic agent is bentonite; the air entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonic acid, fatty alcohol sulfonate, saponin and protein salt, petroleum sulfonate acid; the activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, sodium bisulfate; the retarder is a protein gypsum retarder. The specific performance of the lightweight plastering gypsum is shown in Table 2.

[0234] The preparation method of the lightweight gypsum sand used in the lightweight plastering gypsum of Example 6 is as follows:

[0235] The percentage content of the raw materials of the lightweight gypsum sand is as follows based on the total mass of the raw materials as a percentage:

[0236] Mother particle: perlite filter aid with a particle size of ≤0.102 mm, 7 parts;

[0237] Main material 1: desulfurization gypsum 30 parts, natural gypsum 27 parts, fluorine gypsum 10 parts, phosphorus gypsum 5 parts;

[0238] Main material 2: siliceous mineral 6 parts, kaolin mineral 3 parts, aluminum oxide 3 parts, dolomite 1 part;

[0239] Auxiliary material: slaked lime 2 parts;

[0240] Ball forming material: clay 1 part, bentonite 2 parts, lignin cellulose 1 part;

[0241] Dispersing agent: sodium pyrophosphate 1 part, sodium hexametaphosphate 1 part;

[0242] The preparation method comprises:

[0243] (1) Grinding: the main material 1, main material 2, auxiliary material, and ball forming material are respectively ground to 0.039mm;

[0244] (2) Mud reaction: the main material 1, main material 2, auxiliary material, and ball forming material are added into the stirring kettle with appropriate amount of water for sufficient stirring, the rotating speed is 265r / min, and the stirring time is 8min. At this time, various materials are fully dispersed in water to form mud liquid, and various materials can fully contact and mix uniformly;

[0245] (3) Dewatering: the mud liquid after mud reaction is dewatered by centrifugation, adsorption, and extrusion, and then dried at 245℃ to control the water content of the mud liquid to less than 3% by mass percentage, to obtain blocky material;

[0246] (4) Powdering: the blocky material is ground by a high-speed grinding machine at a rotating speed of 4000r / min to obtain a powder with a particle size of 0.039mm;

[0247] (5) Mother ball formation: the mother particles are poured into a round pan granulator, water is sprayed through the water spray assembly of the granulator to form granules A, and 1 / 3 of the total weight of the powder is added to the granules A. Continue to rotate in the ball mill to form the mother ball;

[0248] (6) Ball formation: the mother ball continues to be sprayed in the granulator, and the remaining powder is added while spraying. Under the condition of rapid rotation of the ball mill, the mother ball gradually increases to form the first ball, and then the dispersing agent is added to form the second ball;

[0249] (7) Screening: the second ball particles obtained in step (6) are screened to remove coarse particles, and the particles with a particle size of 40-140μm are reserved for use;

[0250] (8) Ball shaping: the particles with a particle size of 40-140μm obtained in step (7) are subjected to ball shaping operation again to form more round balls. The roundness of the round balls after shaping operation reaches more than 98%;

[0251] (9) Curing: send the round ball obtained in step (8) to the curing warehouse for curing, and curing is carried out in two stages of water spray curing and dry curing;

[0252] (10) Screen the ball particles obtained in step (9) to obtain light gypsum sand sample 4, the light gypsum sand has a specification of 0.106mm-0.425mm and an internal bulk density of 600kg / m 3 -700kg / m 3 , and other indicators meet the requirements of GB / T 14684-2022 "Construction sand".

[0253] The curing in step (9) is, wherein the water spray curing lasts for 6 days, each time the water spraying lasts for 4 hours, the spraying is carried out once a day, and the temperature in the curing warehouse is 25 degrees Celsius; the dry curing is carried out in the next curing warehouse, and the room temperature is maintained for 14 days. The principle of the curing stage is that the ceramicization reaction of the gypsum in the raw material and the gypsum reaction agent (main material 2) forms ceramic ball particles, so that the product has high strength and water resistance, and the specific performance is shown in Table 1.

[0254] Table 1 Performance test results of light gypsum sand samples 1-4 according to GB / T 14684-2011 "Construction sand"

[0255] 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

[0256] Table 2 Performance test results of light plastering gypsum of examples 1-6 according to light plastering in GB / T 28627-2022 "Plastering gypsum" and JC / T 2497-2018 "Mold-resistant and water-resistant plastering gypsum mortar"

[0257]

[0258]

[0259] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in any other form, and any modification or equivalent change made according to the technical essence of the present application still falls within the scope of the present application.

Claims

1. A high-coated lightweight plastering gypsum, characterized in that, The raw materials of the lightweight plastering gypsum include the following components by weight: Building gypsum: 50-70 parts; Type II anhydrous gypsum: 10-20 parts; 42.5 gray cement: 1-5 parts; Lightweight gypsum sand: 10-45 parts; Vitrified microbeads: 3-5 parts; Thixotropic agent: 0.1-1 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: 0.005-0.02 parts; Activator: 1-8 parts; and Retarder: 0.1-0.5 parts; The preparation method of the lightweight gypsum sand includes: The raw materials of the lightweight gypsum sand include the following components by weight based on the total mass of the raw materials: 5-10 parts of matrix particles, 65-80 parts of main material 1, 10-15 parts of main material 2, 2-5 parts of auxiliary material, 3-5 parts of ball forming material, and 1-10 parts of dispersing agent; Matrix particles: perlite filter aid with a particle size of ≤0.102 mm; Main material 1: any one or a mixture of two or more of natural gypsum, desulfurization gypsum, phosphogypsum, fluorogypsum, titanium gypsum, or other industrial by-product gypsum; Main material 2: any one or a mixture of two or more of aluminate compound, silico-aluminate mineral, dolomite, soluble oxide, and aluminum oxide; Auxiliary material: any one or a mixture of two of active calcium and slaked lime; Ball forming material: any one or a mixture of two or more of clay, lignocellulose, or bentonite, all with a particle size of ≤0.048 mm; Dispersing agent: any one or a mixture of two of sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, or polycarboxylate; (1) Grinding: grinding main material 1, main material 2, auxiliary material, and ball forming material to 0.037±0.005 mm respectively; (2) Mud reaction: adding an appropriate amount of water to main material 1, main material 2, auxiliary material, and ball forming material in a stirring kettle to fully stir at a speed of 50-300 r / min for 5-10 min, at which time the materials are fully dispersed in the water to form a mud liquid, and the materials can fully contact and mix uniformly; (3) Dewatering: after mud reaction, the mud liquid is dewatered by centrifugation, adsorption, and extrusion, and then dried at 150-250°C to control the water content of the mud liquid to less than 3% by mass to obtain a block material; (4) Powdering: grinding the block material through a high-speed grinding machine at a speed of 3000-6000 r / min to obtain a powder with a particle size of 0.037±0.005 mm; (5) Mother ball formation: pouring the matrix particles into a circular pan granulator, spraying water through the water spraying assembly of the granulator to form particles A, adding 1 / 3-1 / 2 of the total weight of the powder to the particles A, and continuously rotating in the ball mill to form mother balls. (6) Spheroid formation: the mother spheres continue to be sprayed with water mist in the granulator while the remaining powder is added, and the mother spheres gradually grow into first spheroids under the rapid rotation of the ball mill. At this point, no water is sprayed, and then the dispersant is added to form second spheroid particles; (7) Screening: the second spheroid particles obtained in step (6) are screened to remove coarse particles, and particles of 40-140 mesh are left for use; (8) Spheroid shaping: the 40-140 mesh particles obtained in step (7) are subjected to spheroid shaping operation again to form more rounded spheroids. The roundness of the rounded spheroids after shaping operation reaches more than 98%; (9) Curing: the rounded spheroids obtained in step (8) are sent to a curing bin for curing. Water mist curing and dry curing are adopted in two stages for curing. (10) The spherical particles obtained in step (9) are sieved to obtain light gypsum sand, wherein the light gypsum sand has a size of 0.106 mm-0.425 mm, and an internal bulk density of 600 kg / m 3 -700 kg / m 3 .

2. A lightweight plastering gypsum according to claim 1, characterized in that The building gypsum has a mass percentage of 80% or more of hemihydrate phase, 4% or less of dihydrate phase, and 5% or less of anhydrite phase, based on the total mass of the building gypsum. The 2h flexural strength of the building gypsum is 3.0 MPa or more, the 2h compressive strength is 6.0 MPa or more, and the chloride ion content is 600 mg / kg or less.

3. A lightweight plastering gypsum according to claim 1 or 2, characterized in that The type II anhydrous hard gypsum has a mass percentage of 96% or more of type II anhydrous gypsum, a softening coefficient of 0.6-0.7, and a pH value of 12-13.

4. A lightweight plastering gypsum according to claim 1 or 2, characterized in that The 42.5 grey cement contains the following ingredients in weight percentage: cement chemical components 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. A lightweight plastering gypsum according to claim 1 or 2, characterised in that The lightweight gypsum sand has a particle size of 40-140 mesh, and a CaSO4 content of 90% or more.

6. A lightweight plastering gypsum according to claim 1 or 2, characterized in that The bulk density of the vitrified microsphere is 100-140 kg / m 3 The particle size is 70-90 mesh, the volume water absorption is less than or equal to 45%, the closed pore rate is greater than or equal to 80%, and the cylinder compressive strength is greater than or equal to 200 KPa.

7. A lightweight plastering gypsum according to claim 1 or 2, characterised in that, The thixotropic agent is a bentonite thixotropic agent.

8. A lightweight plastering gypsum according to claim 1 or 2, characterized in that The starch ether has a water content of 5%, a pH value of 6.0-8.0, and a viscosity of 400-1200 mpas.

9. A lightweight plastering gypsum according to claim 1 or 2, characterized in that, The cellulose ether is hydroxypropyl methylcellulose, and has a viscosity of 40,000-150,000 mpas.

10. A lightweight plastering gypsum according to claim 1 or 2, characterized in that, The air entraining agent is one or more combinations of rosin resin, alkyl and alkyl aromatic sulfonic acid, fatty alcohol sulfonate, saponin, and protein salt, petroleum sulfonate acid.

11. A lightweight plastering gypsum according to claim 1 or 2, characterized in that, The water retaining agent is polyacrylamide.

12. A lightweight plastering gypsum according to claim 1 or 2, characterized in that, The activator is one or more combinations of potassium sulfate, KAl(SO4)2, calcined alum, and sodium bisulfate.

13. A lightweight plastering gypsum according to claim 1 or 2, characterized in that, The retarder is a protein-based gypsum retarder.

14. A process for the production of the lightweight plastering gypsum according to claim 1 or 2, characterized in that The preparation method of the lightweight plastering gypsum comprises the following steps: Step 1: adding building gypsum, type II anhydrous hard gypsum, lightweight gypsum sand, and vitrified microbeads into a stirring kettle, stirring and mixing in the stirring kettle for 3-5 min to obtain a glue material and aggregate mixture; Step 2: pre-dispersing the activator, cellulose ether, thixotropic agent, retarder, starch ether, polyacrylamide, air entraining agent, and heavy calcium to obtain an additive mixture; Step 3: putting the additive mixture into the stirring kettle, and dry mixing and stirring the glue material and aggregate mixture for 3-5 min to obtain the lightweight plastering gypsum with high coating rate.

15. The method of claim 14, wherein, The preparation method of the light gypsum sand comprises: The raw material weight parts of the light gypsum sand are, based on the total mass of the raw material as a percentage basis: 5-10 parts of matrix particles, 65-80 parts of main material 1, 10-15 parts of main material 2, 2-5 parts of auxiliary material, 3-5 parts of ball forming material, and 1-10 parts of dispersing agent; The matrix particle: perlite filter aid with a particle size ≤0.102 mm; The main material 1: any one or a mixture of two or more of natural gypsum, desulfurization gypsum, phosphogypsum, fluorogypsum, titanium gypsum, or other industrial by-product gypsum; The main material 2: any one or a mixture of two or more of an aluminate compound, a silico-alumina mineral, dolomite, a soluble oxide, and aluminum oxide; The auxiliary material: any one or a mixture of two of active calcium and slaked lime; The ball forming material: any one or a mixture of two or more of clay, lignocellulose, or bentonite, all with a particle size ≤0.048 mm; The dispersing agent: any one or a mixture of two of sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, or a polycarboxylate; The preparation method comprises: (1) Grinding: grinding the main material 1, the main material 2, the auxiliary material, and the ball forming material to 0.037±0.005 mm respectively; (2) Mud reaction: adding the main material 1, the main material 2, the auxiliary material, and the ball forming material into a stirring kettle with an appropriate amount of water, fully stirring at a speed of 50-300 r / min for 5-10 min, at which time the various materials are fully dispersed in the water to form a mud liquid, and the materials can fully contact and mix uniformly; (3) Dewatering: after the mud reaction, the mud liquid is dewatered by centrifugation, adsorption, and extrusion, and then dried at 150-250°C to control the water content of the mud liquid to less than 3% by mass, to obtain a block material; (4) Powdering: grinding the block material through a high-speed pulverizer at a speed of 3000-6000 r / min to obtain a powder with a particle size of 0.037±0.005 mm; (5) Mother ball formation: pouring the matrix particles into a round pan granulator, spraying water through the water spray assembly of the granulator to form particles A, and adding 1 / 3-1 / 2 of the total weight of the powder into the particles A, and continuously rotating in the ball mill to form mother balls; (6) Ball formation: continuously spraying water in the granulator while adding the remaining powder, and gradually increasing the size of the mother balls to form first ball bodies under the rapid rotation of the ball mill, at which time no more water is sprayed, and then the dispersing agent is added to form second ball bodies; (7) Sieving: removing coarse particles from the second ball bodies obtained in step (6) to leave particles with a particle size of 40-140 mesh for use; (8) Ball shaping: performing ball shaping again on the particles with a particle size of 40-140 mesh obtained in step (7) to form more rounded ball bodies, and the roundness of the rounded ball bodies after the shaping operation reaches more than 98%; (9) Curing: sending the rounded ball bodies obtained in step (8) to a curing bin for curing, and adopting two stages of water spray curing and dry curing for curing; (10) The spherical particles obtained in step (9) are sieved to obtain light gypsum sand, wherein the light gypsum sand has a size of 0.106 mm-0.425 mm, and an internal bulk density of 600 kg / m 3 -700 kg / m 3 .

16. The method of claim 15, wherein, The maintenance in step (9) is that, the water spray maintenance lasts for 4-7 days, the water spraying lasts for 4 hours each time, the water spraying is carried out once a day, the temperature of the maintenance warehouse is 15-25 DEG C; the dry maintenance is carried out in the next maintenance warehouse, and the room temperature is maintained for 11-14 days.

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