Composite grinding aid for low-carbon low-heat cement clinker and preparation method thereof

Abstract

The application provides a composite grinding aid for low-carbon and low-heat cement clinker and a preparation method thereof. The composite grinding aid comprises the following raw material components in percentage by mass: DMDAAC-co-AA 6-10%, DMC-co-AA 3-5%, alcohol amine 12-17%, polyhydric alcohol 10-15%, molasses 10-13%, graphene oxide solution 30-40%, and the rest is water. The composite grinding aid can greatly improve the ball milling dispersibility and early mechanical strength of the low-carbon and low-heat cement clinker by introducing the amphoteric surfactant intermediate and supplementing a small amount of graphene oxide and other components.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and in particular relates to a composite grinding aid for low-carbon, low-heat cement clinker and its preparation method. Background Technology

[0002] Under the goal of achieving "dual carbon" in the cement industry, reducing carbon emissions during the firing and grinding processes of cement clinker is one of the important ways to save energy and reduce emissions. Currently, low-carbon, low-heat cement clinker dominated by C2S (content exceeding 40%) has emerged, possessing excellent low-carbon and energy-saving characteristics such as lower firing temperature (reduced by approximately 100°C or more), lower energy load, lower environmental load, and lower resource load. Furthermore, it also exhibits good workability and durability, thus having broad application prospects. However, compared to traditional silicate clinker with C3S as the main mineral, low-carbon, low-heat cement clinker has disadvantages such as poor grindability and low early strength.

[0003] Currently, the grinding aids commonly used in the market for low-carbon, low-heat cement clinker mainly consist of alkanolamines and molasses. These grinding aids have limited effect on the ball milling dispersion and early strength improvement of low-carbon, low-heat cement clinker. Therefore, there is a need to develop a grinding aid that can significantly improve the ball milling dispersibility and early mechanical strength of low-carbon, low-heat cement clinker. Summary of the Invention

[0004] In view of this, in order to solve the technical problems of poor ball milling dispersibility and low early strength of low-carbon and low-heat cement clinker, the present invention proposes a composite grinding aid for low-carbon and low-heat cement clinker. The composite grinding aid of the present invention introduces an amphoteric surfactant intermediate and is supplemented with a small amount of graphene oxide and other components. The resulting composite grinding aid can significantly improve the ball milling dispersibility and early mechanical strength of low-carbon and low-heat cement clinker. The present invention also provides a simple preparation method for the composite grinding aid for low-carbon and low-heat cement clinker through multi-component compounding.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] The present invention provides a composite grinding aid for low-carbon and low-heat cement clinker, comprising the following raw material components by mass percentage: 6%–10% DMDAAC-co-AA, 3%–5% DMC-co-AA, 12%–17% alkanolamine, 10%–15% polyol, 10%–13% molasses, 30%–40% graphene oxide solution, and the remainder being water, totaling 100%.

[0007] The DMDAAC-co-AA is prepared by the following method: L-ascorbic acid (Vc), water and dimethyl diallyl ammonium chloride (DMDAAC) are mixed evenly to obtain substrate one; acrylic acid (AA) and mercaptopropionic acid (3-MTA) are mixed evenly to obtain component A; hydrogen peroxide (H2O2) and water are mixed evenly to obtain component B; components A and B are added dropwise to substrate one until the reaction is complete to obtain the DMDAAC-co-AA;

[0008] The free radical copolymerization equation of DMDAAC and AA is as follows:

[0009]

[0010]

[0011] The DMC-co-AA is prepared as follows: sodium bisulfite (NaHSO3), water, methacryloyloxyethyltrimethylammonium chloride (DMC), and mercaptopropionic acid (3-MTA) are mixed evenly to obtain substrate two; acrylic acid (AA), sodium bisulfite (NaHSO3), and water are mixed evenly to obtain substrate C; potassium persulfate (K2S2O8) and water are mixed evenly to obtain substrate D; substrate C and substrate D are added dropwise to substrate two until the reaction is complete to obtain the DMC-co-AA.

[0012] The free radical copolymerization equation of DMC and AA is as follows:

[0013]

[0014] In some preferred embodiments of the composite grinding aid for low-carbon, low-heat cement clinker of the present invention, the raw material components include the following by mass percentage: 8% DMDAAC-co-AA, 5% DMC-co-AA, 15% alkanolamine, 12% polyol, 13% molasses, 35% graphene oxide solution, and 12% water.

[0015] In some preferred embodiments of the composite grinding aid for low-carbon, low-heat cement clinker of the present invention, the weight parts of each component in the first base material are: 0.06-0.4 parts L-ascorbic acid, 1.84-3 parts water, and 70-72 parts dimethyl diallyl ammonium chloride; the weight parts of each component in the A material are: 14-20 parts acrylic acid and 1.5-2.0 parts mercaptopropionic acid; and the weight parts of each component in the B material are: 0.6-1.2 parts hydrogen peroxide and 3.4-10 parts water.

[0016] The mass concentration of the dimethyl diallyl ammonium chloride is 60%; the mass concentration of the acrylic acid is 99.5%; the mass concentration of the mercaptopropionic acid is 99.5%; the mass concentration of the hydrogen peroxide is 27.5%; and the L-ascorbic acid is industrial grade.

[0017] In some preferred embodiments of the composite grinding aid for low-carbon, low-heat cement clinker of the present invention, the weight parts of each component in the first base material are: 0.06 parts of L-ascorbic acid, 1.84 parts of water, and 72 parts of dimethyl diallyl ammonium chloride; the weight parts of each component in the A material are: 14 parts of acrylic acid and 1.5 parts of mercaptopropionic acid; and the weight parts of each component in the B material are: 0.6 parts of hydrogen peroxide and 10 parts of water.

[0018] In some preferred embodiments of the composite grinding aid for low-carbon, low-heat cement clinker of the present invention, the weight parts of each component in the second base material are: sodium bisulfite 0.1-0.2 parts, water 2-5 parts, methacryloyloxyethyltrimethylammonium chloride 52-70 parts, and mercaptopropionic acid 0.3-0.7 parts; the weight parts of each component in the C material are: acrylic acid 10-13 parts, sodium bisulfite 0.1-0.2 parts, and water 6-15 parts; and the weight parts of each component in the D material are: potassium persulfate 0.8-1.5 parts and water 6.7-16.3 parts.

[0019] The mass concentration of the methacryloyloxyethyltrimethylammonium chloride is 80.0%; the mass concentration of the acrylic acid is 99.5%; the mass concentration of the mercaptopropionic acid is 99.5%; and the sodium bisulfite, sodium bisulfite, and potassium persulfate are all industrial grade.

[0020] In some preferred embodiments of the composite grinding aid for low-carbon, low-heat cement clinker of the present invention, the weight parts of each component in the second base material are: 0.1 parts sodium bisulfite, 5 parts water, 52 parts methacryloyloxyethyltrimethylammonium chloride, and 0.7 parts mercaptopropionic acid; the weight parts of each component in the C material are: 10 parts acrylic acid, 0.1 parts sodium bisulfite, and 15 parts water; and the weight parts of each component in the D material are: 0.8 parts potassium persulfate and 16.3 parts water.

[0021] In some preferred embodiments of the composite grinding aid for low-carbon, low-heat cement clinker of the present invention, the alkanolamine is one or a combination of diethanolamine, triethanolamine, and diethanol monoisopropanolamine.

[0022] In some preferred embodiments of the composite grinding aid for low-carbon, low-heat cement clinker of the present invention, the alkanolamine is a mixture of diethanolamine and diethanol monoisopropanolamine, with a mass ratio of 1.5-2.0:0.8-1.2.

[0023] In some preferred embodiments of the composite grinding aid for low-carbon, low-heat cement clinker of the present invention, the polyol is one or a combination of two of ethylene glycol and glycerol.

[0024] In some preferred embodiments of the composite grinding aid for low-carbon, low-heat cement clinker of the present invention, the molasses is a by-product produced during the sugar refining process, wherein the sucrose content is about 24% to 36% by mass, other sugars are about 10% to 22%, and soluble colloids are about 2% to 4%.

[0025] In some preferred embodiments of the composite grinding aid for low-carbon and low-heat cement clinker of the present invention, the graphene oxide solution is prepared by the following method: graphene oxide powder is deeply purified by deionized water and prepared into a solution with a concentration of 3.5 g / L; the solution is then ultrasonically treated in water to obtain the graphene oxide solution, and its physicochemical properties are shown in Table 1.

[0026] Table 1 Basic Physicochemical Properties of Graphene Oxide Solution

[0027]

[0028] The second aspect of the present invention provides a method for preparing a composite grinding aid for low-carbon and low-heat cement clinker: water is added to a reaction vessel, and then DMDAAC-co-AA, DMC-co-AA, alkanolamine, polyol, molasses, and graphene oxide solution are added in sequence, the solution temperature is maintained at about 22-28°C, preferably 25°C, and the mixture is stirred evenly to obtain the composite grinding aid.

[0029] A third aspect of the present invention provides a surfactant for preparing a composite grinding aid: the surfactant is prepared by the following two methods:

[0030] Route 1, free radical copolymerization reaction at room temperature (25℃), the specific process is as follows: 0.06-0.4 parts by weight of L-ascorbic acid, 1.84-3 parts by weight of water, and 70-72 parts by weight of dimethyl diallyl ammonium chloride are mixed evenly to obtain substrate 1; 14-20 parts by weight of acrylic acid and 1.5-2.0 parts by weight of mercaptopropionic acid are mixed evenly to obtain component A; 0.6-1.2 parts by weight of hydrogen peroxide and 3.4-10 parts by weight of water are mixed evenly to obtain component B; at room temperature, components A and B are added dropwise to substrate 1, and after the addition is complete, the mixture is kept warm and stirred until the reaction is complete to obtain the surfactant DMDAAC-co-AA;

[0031] Route 2, free radical copolymerization reaction at room temperature (25℃), the specific process is as follows: 0.1-0.2 parts by weight of sodium bisulfite, 2-5 parts by weight of water, 52-70 parts by weight of methacryloyloxyethyltrimethylammonium chloride, and 0.3-0.7 parts by weight of mercaptopropionic acid are mixed evenly to obtain substrate 2; 10-13 parts by weight of acrylic acid, 0.1-0.2 parts by weight of sodium bisulfite, and 6-15 parts by weight of water are mixed evenly to obtain substrate C; 0.8-1.5 parts by weight of potassium persulfate and 6.7-16.3 parts by weight of water are mixed evenly to obtain substrate D; at room temperature, substrate C and substrate D are added dropwise to substrate 2, and after the addition is complete, the mixture is kept warm and stirred until the reaction is complete to obtain the surfactant DMC-co-AA.

[0032] Compared with existing technologies, the low-carbon, low-heat composite grinding aid for cement clinker and its preparation method described in this invention have the following advantages:

[0033] (1) The composite grinding aid for low-carbon and low-heat cement clinker described in this invention introduces amphoteric surfactant intermediates DMDAAC-co-AA and DMC-co-AA. The molecular structures of the two are designable, and they can promote the rapid hydration of C3S in low-carbon and low-heat cement clinker and generate as many amorphous fibrous or clustered CSH gels as possible in the hydration products. This has a good effect on improving the early strength performance of low-carbon and low-heat cement clinker.

[0034] (2) In the composite grinding aid for low-carbon and low-heat cement clinker described in this invention, the solution system of the composite grinding aid is made more stable by adding graphene oxide solution. The nano-sized sheet-like graphene oxide has a large specific surface area and contains a large number of active groups such as -OH and -COOH. It plays a 'template effect' in the cement hydration process. It has the effect of inducing and promoting the growth of cement hydration crystals. In particular, it can be adsorbed on the surface of C3S mineral through complexation, promoting the formation of CH and CSH. This will accelerate cement hydration and thus help improve the early mechanical properties of low-carbon and low-heat cement clinker. In addition, the nanosheet structure of graphene oxide has the effect of refining the pore structure of hydration products and hindering crack formation, thereby improving the hardening strength of low-carbon and low-heat cement clinker.

[0035] (3) In the composite grinding aid for low-carbon and low-heat cement clinker described in this invention, alkanolamines form a synergistic effect with graphene oxide, DMDAAC-co-AA and DMC-co-AA, which together enhance the hydration activity of low-carbon and low-heat cement clinker powder.

[0036] (4) In the composite grinding aid for low-carbon and low-heat cement clinker described in this invention, the combination of polyol and molasses improves the ball milling dispersibility of low-carbon and low-heat cement clinker, optimizes the particle size distribution, increases the clinker production per grinding table by about 6-10%, and saves energy consumption by about 10-15%.

[0037] (5) The low-carbon and low-heat cement clinker composite grinding aid described in this invention is produced by a heat-free, atmospheric-pressure process with no wastewater or waste gas emissions, making it green and environmentally friendly. Attached Figure Description

[0038] Figure 1 This is a diagram of the experimental apparatus for the synthesis process of DMDAAC-co-AA described in this invention. Detailed Implementation

[0039] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0040] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0041] Example 1: Preparation of DMDAAC-co-AA

[0042] like Figure 1 As shown, DMDAAC-co-AA was prepared as follows (raw material ratios are shown in Table 2, a total of 4 ratios), via free radical copolymerization at room temperature (25℃):

[0043] L-ascorbic acid (Vc) and water are stirred until completely dissolved, then dimethyl diallyl ammonium chloride (DMDAAC) is added and stirred until completely mixed to obtain base material one;

[0044] Acrylic acid (AA) and mercaptopropionic acid (3-MTA) are mixed evenly to obtain material A;

[0045] Mix hydrogen peroxide (H2O2) and water evenly to obtain material B;

[0046] Add components A and B slowly dropwise into the substrate. After 2 hours, the addition is complete. Continue to keep warm and stir for 1 hour until the reaction is complete to obtain the surfactant DMDAAC-co-AA.

[0047] Table 2. Raw material ratio for the synthesis of DMDAAC-co-AA (%)

[0048]

[0049] The mass concentration of dimethyl diallyl ammonium chloride is 60%, the mass concentration of acrylic acid is 99.5%, the mass concentration of mercaptopropionic acid is 99.5%, the mass concentration of hydrogen peroxide is 27.5%, and L-ascorbic acid is industrial grade.

[0050] Example 2: Preparation of DMC-co-AA

[0051] DMC-co-AA was prepared as follows (raw material ratios are shown in Table 3, a total of 4 ratios), via free radical copolymerization at room temperature (25℃):

[0052] Sodium bisulfite (NaHSO3) and water are stirred until completely dissolved, then methacryloyloxyethyltrimethylammonium chloride (DMC) and mercaptopropionic acid (3-MTA) are added and stirred until completely mixed to obtain base material two;

[0053] Acrylic acid (AA), sodium bisulfite (NaHSO3) and water are mixed evenly to obtain material C;

[0054] Potassium persulfate (K2S2O8) and water are mixed evenly to obtain material D;

[0055] Add components C and D slowly dropwise into the substrate 2. After 2 hours, the addition is complete. Continue to keep warm and stir for 1 hour until the reaction is complete to obtain the surfactant DMC-co-AA.

[0056] Table 3. Raw material ratios for the synthesis of DMC-co-AA (%)

[0057]

[0058] The mass concentration of methacryloyloxyethyltrimethylammonium chloride is 80.0%, the mass concentration of acrylic acid is 99.5%, the mass concentration of mercaptopropionic acid is 99.5%, and sodium bisulfite, sodium bisulfite, and potassium persulfate are all industrial grade.

[0059] Examples 3-5: Preparation of composite grinding aids for low-carbon, low-heat cement clinker

[0060] In the embodiments of Examples 3 to 5, unless otherwise specified, the composite grinding aids were prepared in the following manner (the raw material ratios of Examples 3 to 5 are shown in Table 4):

[0061] Deionized water was added to the reaction vessel, followed by the sequential addition of DMDAAC-co-AA, DMC-co-AA, alkanolamine, polyol, molasses, and graphene oxide solution. The solution temperature was maintained at 25°C, and the mixture was stirred for 2 hours until it was safely and uniformly mixed to obtain the composite grinding aid.

[0062] The grinding aids prepared in Comparative Examples 1 and 2 were obtained as follows (the raw material ratios of Comparative Examples 1 and 2 are shown in Table 4): first, deionized water was added, then alcoholamine, polyol and molasses were added in sequence, and the mixture was stirred at room temperature of 25°C for 2.0 h until it was completely mixed.

[0063] Table 4. Raw material proportions (%) of composite grinding aids for low-carbon, low-heat cement clinker

[0064] Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 DMDAAC-co-AA 8 8 8 0 0 DMC-co-AA 5 5 5 0 0 Diethanolmonoisopropanolamine 7 6 5 0 12 diethanolamine 8 4 10 27 13 Triethanolamine 0 5 0 3 5 Ethylene glycol 6 3 0 4 2 Glycerol 6 9 12 8 10 Molasses 13 13 13 15 15 Graphene oxide solution 35 35 35 0 0 Deionized water 12 12 12 43 43

[0065] Among them, 1) DMDAAC-co-AA is prepared from formulation IV in Example 1;

[0066] 2) DMC-co-AA was prepared from formulation IV in Example 2;

[0067] 3) When adding amines and polyols in combination, they should be mixed evenly according to the ratio in Table 4 before being added to the solution system;

[0068] 4) Molasses is a type of sugarcane molasses, which is a byproduct of sugar refining. It contains about 24-36% sucrose, about 10-22% other sugars, and about 2-4% soluble colloids.

[0069] 5) The basic physicochemical properties of the graphene oxide solution are shown in Table 1.

[0070] Comparative Example 3 is a commercially available high-performance cement grinding aid from a company in Guangdong Province. It is a brownish-red liquid with a solid content of 47% to 50% and a pH of 5 to 6.5. The recommended dosage is 1.0‰.

[0071] Performance testing

[0072] 1. Experimental conditions:

[0073] 1) The mineral composition of low-carbon, low-heat cement clinker is shown in Table 5:

[0074] Table 5. Mineral composition (%) of low-carbon, low-heat cement clinker

[0075] clinker minerals <![CDATA[C3A]]> <![CDATA[C3S]]> <![CDATA[C2S]]> <![CDATA[C4AF]]> f-CaO content ＜6 20-35 40-60 5-12 ＜1.0

[0076] 2) In accordance with the requirements of GB / T26748-2011 "Cement Grinding Aids", the technical parameters of the experimental small ball mill are shown in Table 6:

[0077] Table 6 Technical parameters of the experimental small ball mill

[0078]

[0079] 3) In accordance with the requirements of GB / T26748-2011 "Cement Grinding Aids", a small ball mill was used to test low-carbon, low-heat cement clinker, including the following steps:

[0080] (1) Washing and grinding: Weigh an appropriate amount of material to be ground and place it in the mill to grind for 10-15 minutes to clean up other impurities in the mill.

[0081] (2) Weighing: Accurately weigh the materials to be ground using a balance, including 5 kg of gypsum and other mineral admixtures. According to the test requirements, after weighing the materials, add the grinding aid to the materials according to the required specifications, and then mix them evenly.

[0082] (3) Loading: Place the evenly mixed material into the ball mill for grinding, and adjust the time. The ball milling time for cement clinker is 20 minutes.

[0083] (4) Grinding: If it is required to take samples to test the fineness or specific surface area of ​​the material during the grinding process, the mill door should be opened to take samples 2-3 minutes after the machine is stopped and the powder settles. When the specified time is reached, the mill should be stopped and the grid plate should be replaced before starting the mill to discharge the material.

[0084] 4) The evaluation of ball milling indices for low-carbon, low-heat cement clinker includes the following two aspects:

[0085] (1) Measure the specific surface area of ​​low-carbon, low-heat cement clinker after ball milling according to the requirements of JC / T721-2006 "Method for Determination of Cement Particle Size Distribution by Laser Method".

[0086] (2) Test the strength of cement mortar according to the requirements of GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)".

[0087] 5) In accordance with the requirements of GB / T 8077-2012 "Test Method for Homogeneity of Concrete Admixtures", the solid content of the composite grinding aid for low-carbon and low-heat cement clinker in Examples 3-5 and Comparative Examples 1 and 2 was measured to be 45%-50%, and the solid content of the commercially available grinding aid in Comparative Example 3 was 47%-50%.

[0088] 6) In accordance with the recommended dosage in GB / T26748-2011 "Cement Grinding Aids", the dosage of the composite grinding aids described in Examples 3 to 5 and the grinding aids described in Comparative Examples 1 to 3 is 1.0‰.

[0089] 2. Experimental procedure and results:

[0090] 1) In accordance with the requirements of GB175-2007 "General Portland Cement" and GB / T 200-2017 "Medium-heat Portland Cement, Low-heat Portland Cement", the proportion of the prepared P·LH (P·I type) cement is 95% low-carbon low-heat cement clinker and 5% desulfurized gypsum.

[0091] Examples 3-5 and Comparative Examples 1-3 were added at 1.0‰ to P·LH (P·I type) cement, and the specific surface area after ball milling for 20 min is shown in Table 7:

[0092] Table 7. Specific surface area (m²) of P·LH (P·I type) cement 2 / kg)

[0093]

[0094] As shown in Table 7, the composite grinding aids prepared in Examples 3-5 with 1.0‰ addition and the grinding aids in Comparative Examples 1-3 can all increase the ball mill specific surface area of ​​low-carbon and low-heat cement clinker. However, the data results of the composite grinding aids prepared in the examples are significantly better than those of the comparative examples. Among them, the P·LH (P·I type) cement with the composite grinding aid prepared in Example 3 has the largest specific surface area.

[0095] GB / T 200-2017 "Medium-heat Silicate Cement and Low-heat Silicate Cement" requires the hydration heat index of P·LH type cement as shown in Table 8:

[0096] Table 8. Hydration heat index of P·LH type cement

[0097]

[0098] Examples 3-5 and Comparative Examples 1-3 were added at 1.0‰ to P·LH (P·I type) cement, and the hydration heat test results are shown in Table 9:

[0099] Table 9. Test Results of Hydration Heat of P·LH (P·I Type) Cement

[0100]

[0101] As shown in Tables 8 and 9, the strength grade of P·LH (P·I type) cement meets 42.5. The addition of 1.0‰ of the composite grinding aid prepared in Examples 3 to 5 and the grinding aid in Comparative Examples 1 to 3 has little effect on the heat of hydration of cement and meets the corresponding standards.

[0102] GB / T 200-2017 "Medium-heat Silicate Cement and Low-heat Silicate Cement" requires the 3-day, 7-day, and 28-day strength indicators of P·LH type cement as shown in Table 10:

[0103] Table 10 shows the 3-day, 7-day, and 28-day strength indices of P·LH type cement.

[0104]

[0105] Examples 3-5 and Comparative Examples 1-3 were added at 1.0‰ to low-carbon, low-heat cement clinker. The P·LH (P·I type) cement after ball milling for 20 min was tested for 3-day, 7-day, and 28-day flexural and compressive strengths according to the requirements of GB / T 17671-2021, as shown in the table below:

[0106] Table 11 Test Results of Flexural and Compressive Strength of P·LH (P·I Type) Cement

[0107]

[0108] As shown in Tables 10 and 11, the flexural and compressive strengths of P·LH (P·I type) cement both meet the requirements of GB / T200-2017, and their strength grades reach 42.5. Furthermore, the strength values ​​of the composite grinding aids prepared in Examples 3-5 with 1‰ admixture are slightly higher than those with the grinding aids prepared in Comparative Examples 1-3, and the cement mortar with the composite grinding aid prepared in Example 5 with 1‰ admixture exhibits the best flexural and compressive strength values.

[0109] 2) In accordance with the requirements of GB175-2007 "General Portland Cement" and GB / T 200-2017 "Medium-Heat Portland Cement and Low-Heat Portland Cement", the proportion of the prepared P·LH (P·O+F type) cement is 85% low-carbon low-heat cement clinker, 12% fly ash and 3% desulfurized gypsum; the proportion of the prepared P·LH (P·O+S type) cement is 85% low-carbon low-heat cement clinker, 12% mineral powder and 3% desulfurized gypsum.

[0110] Examples 3-5 and Comparative Examples 1-3 were mixed with 1‰ of P·LH (P·O+F type) and P·LH (P·O+S type) cement, and the specific surface area after ball milling for 20 minutes is shown in Table 12:

[0111] Table 12 Specific surface area (m²) of P·LH (P·O+F type) cement and P·LH (P·O+S type) cement 2 / kg)

[0112]

[0113] As shown in Table 12, the addition of the composite grinding aids prepared in Examples 3 to 5 can increase the specific surface area of ​​P·LH (P·O+F type) cement and P·LH (P·O+S type) cement. Among them, the P·LH (P·O+F type) cement and P·LH (P·O+S type) cement with the addition of the composite grinding aid prepared in Example 5 have the largest specific surface area and the best ball milling dispersion effect.

[0114] Examples 3-5 and Comparative Examples 1-3 were added at 1‰ to P·LH (P·O+F type) cement and P·LH (P·O+S type) cement, and the hydration heat test results are shown in Table 13:

[0115] Table 13. Hydration heat test results of P·LH (P·O+F type) cement and P·LH (P·O+S type) cement

[0116]

[0117] As shown in Table 13, both P·LH (P·O+F type) cement and P·LH (P·O+S type) cement meet the requirements for heat of hydration of low-heat cement in GB / T200-2017. The overall trend is that the heat of hydration of the two types of cement with the composite grinding aid prepared in Examples 3 to 5 is slightly greater than that of the two types of cement with the grinding aid prepared in Comparative Examples 1 to 3.

[0118] Examples 3-5 and Comparative Examples 1-3 were selected and added at 1‰ to low-carbon, low-heat cement clinker. The 3-day, 7-day, and 28-day flexural and compressive strengths of P·LH (P·O+F type) cement and P·LH (P·O+S type) cement after ball milling for 20 minutes were tested according to the requirements of GB / T17671-2021, as shown in Tables 14 and 15.

[0119] Table 14. Test results of flexural and compressive strength of P·LH (P·O+F type) cement

[0120]

[0121]

[0122] Table 15. Test results of flexural and compressive strength of P·LH (P·O+S type) cement

[0123]

[0124] As shown in Tables 14 and 15, the mechanical properties of P·LH (P·O+F type) and P·LH (P·O+S type) cements meet the requirements of GB / T 200-2017, and their strength grades both reach 42.5. Furthermore, the strength values ​​of the two types of cements with 1‰ of the composite grinding aid prepared in Examples 3-5 are slightly higher than those with the grinding aid prepared in Comparative Examples 1-3. Meanwhile, the 3-day and 7-day strength values ​​of P·LH (P·O+S type) cement are slightly higher, while the 28-day strength of P·LH (P·O+S type) cement is relatively high. Among all flexural and compressive strengths of the two types of cements, the two types of cement with 1‰ of the composite grinding aid prepared in Example 5 have the highest strength values.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite grinding aid for low-carbon, low-heat cement clinker, characterized in that, The raw material components, by mass percentage, are as follows: DMDAAC-co-AA 6%–10%, DMC-co-AA 3%–5%, alkanolamine 12%–17%, polyol 10%–15%, molasses 10%–13%, graphene oxide solution 30%–40%, and the remainder is water, totaling 100%. The DMDAAC-co-AA is prepared by the following method: L-ascorbic acid, water and dimethyl diallyl ammonium chloride DMDAAC are mixed evenly to obtain substrate one; acrylic acid AA and mercaptopropionic acid are mixed evenly to obtain component A; hydrogen peroxide and water are mixed evenly to obtain component B; component A and component B are added dropwise to substrate one until the reaction is complete to obtain the DMDAAC-co-AA. The DMC-co-AA is prepared by mixing sodium bisulfite, water, methacryloyloxyethyltrimethylammonium chloride (DMC), and mercaptopropionic acid to obtain substrate two; mixing AA, sodium bisulfite, and water to obtain substrate C; and mixing potassium persulfate and water to obtain substrate D; adding substrate C and substrate D dropwise to substrate two until the reaction is complete to obtain the DMC-co-AA.

2. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 1, characterized in that: The raw material components include the following by mass percentage: DMDAAC-co-AA 8%, DMC-co-AA 5%, alkanolamine 15%, polyol 12%, molasses 13%, graphene oxide solution 35%, and water 12%.

3. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 1, characterized in that: In the first base material, the weight parts of each component are: L-ascorbic acid 0.06-0.4 parts, water 1.84-3 parts, and dimethyl diallyl ammonium chloride 70-72 parts; in the A component, the weight parts of each component are: acrylic acid 14-20 parts and mercaptopropionic acid 1.5-2.0 parts; in the B component, the weight parts of each component are: hydrogen peroxide 0.6-1.2 parts and water 3.4-10 parts. The mass concentration of the dimethyl diallyl ammonium chloride is 60%; the mass concentration of the acrylic acid is 99.5%; the mass concentration of the mercaptopropionic acid is 99.5%; the concentration of the hydrogen peroxide is 27.5%; and the L-ascorbic acid is industrial grade.

4. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 3, characterized in that: In the first base material, the weight parts of each component are: 0.06 parts L-ascorbic acid, 1.84 parts water, and 72 parts dimethyl diallyl ammonium chloride; in the A component, the weight parts of each component are: 14 parts acrylic acid and 1.5 parts mercaptopropionic acid; in the B component, the weight parts of each component are: 0.6 parts hydrogen peroxide and 10 parts water.

5. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 1, characterized in that: In the second base material, the weight parts of each component are: sodium bisulfite 0.1-0.2 parts, water 2-5 parts, methacryloyloxyethyltrimethylammonium chloride 52-70 parts, and mercaptopropionic acid 0.3-0.7 parts; in the third material, the weight parts of each component are: acrylic acid 10-13 parts, sodium bisulfite 0.1-0.2 parts, and water 6-15 parts; in the fourth material, the weight parts of each component are: potassium persulfate 0.8-1.5 parts, and water 6.7-16.3 parts. The mass concentration of the methacryloyloxyethyltrimethylammonium chloride is 80.0%; the mass concentration of the acrylic acid is 99.5%; the mass concentration of the mercaptopropionic acid is 99.5%; and the sodium bisulfite and potassium persulfate are both industrial grade.

6. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 5, characterized in that: In the second base material, the weight parts of each component are: 0.1 parts sodium bisulfite, 5 parts water, 52 parts methacryloyloxyethyltrimethylammonium chloride, and 0.7 parts mercaptopropionic acid; in the third material, the weight parts of each component are: 10 parts acrylic acid, 0.1 parts sodium bisulfite, and 15 parts water; in the fourth material, the weight parts of each component are: 0.8 parts potassium persulfate and 16.3 parts water.

7. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 1, characterized in that: The alkanolamine is one or a combination of several of diethanolamine, triethanolamine, and diethanol monoisopropanolamine.

8. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 7, characterized in that: The alkanolamine is a mixture of diethanolamine and diethanol monoisopropanolamine, with a mass ratio of 1.5–2.0:0.8–1.

2.

9. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 1, characterized in that: The polyol is one or a combination of two of ethylene glycol and glycerol.

10. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 1, characterized in that: The molasses contains 24%–36% sucrose by mass, 10%–22% other sugars, and 2%–4% soluble colloids.

11. The composite grinding aid for low-carbon, low-heat cement clinker according to claim 1, characterized in that: The graphene oxide solution was prepared by: deeply purifying graphene oxide powder with deionized water to prepare a solution with a concentration of 3.5 g / L; and then sonicating the solution in water to obtain the graphene oxide solution.

12. The method for preparing the composite grinding aid for low-carbon, low-heat cement clinker according to any one of claims 1 to 11, characterized in that: Water was added to the reaction vessel, followed by the sequential addition of DMDAAC-co-AA, DMC-co-AA, alkanolamine, polyol, molasses, and graphene oxide solution. The solution temperature was maintained at 22–28°C, and the mixture was stirred until homogeneous to obtain the composite grinding aid.

13. A surfactant for preparing composite grinding aids, characterized in that: The surfactant is prepared by the following two methods: Route 1: Mix 0.06-0.4 parts by weight of L-ascorbic acid, 1.84-3 parts by weight of water, and 70-72 parts by weight of dimethyl diallyl ammonium chloride to obtain substrate 1; mix 14-20 parts by weight of acrylic acid and 1.5-2.0 parts by weight of mercaptopropionic acid to obtain component A; mix 0.6-1.2 parts by weight of hydrogen peroxide and 3.4-10 parts by weight of water to obtain component B; at room temperature, add components A and B dropwise to substrate 1, and continue stirring while keeping warm until the reaction is complete to obtain surfactant DMDAAC-co-AA; Route 2: Mix 0.1-0.2 parts by weight of sodium bisulfite, 2-5 parts by weight of water, 52-70 parts by weight of methacryloyloxyethyltrimethylammonium chloride, and 0.3-0.7 parts by weight of mercaptopropionic acid to obtain base material 2; mix 10-13 parts by weight of acrylic acid, 0.1-0.2 parts by weight of sodium bisulfite, and 6-15 parts by weight of water to obtain material C; mix 0.8-1.5 parts by weight of potassium persulfate and 6.7-16.3 parts by weight of water to obtain material D; at room temperature, add materials C and D dropwise to base material 2, and continue to keep warm and stir until the reaction is complete to obtain surfactant DMC-co-AA.

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