Cement grinding aid, its preparation method and application

Abstract

The application discloses a cement grinding aid, and ingredients are as follows in parts by mass: fly ash 300-500, organic grinding component 15-40, inorganic grinding component 2-8, dehydrating agent 1-3, water absorbing agent 3-6, hydrophobic silicon dioxide 2-5, and double-end silane polyethylene glycol 8-13; the application optimizes component matching, improves the ability of the surface of cement particles to resist moisture in the mixture, effectively accelerates the absorption and volatilization of moisture in the mixture, effectively improves the flowability of cement powder in the mill, and solves the problems of paste ball and mill, reduced yield in the ball milling process of raw materials with high moisture content, and reduced strength in the application process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of materials, and particularly relates to a cement grinding aid and a preparation method and application thereof. BACKGROUND

[0002] At present, cement concrete has become one of the engineering structure materials with the largest consumption and the most extensive use, and has become an important material basis for the development of human society. The cement industry is not only a large consumer of resources and energy and a large emitter of carbon dioxide, but also has great energy-saving and emission-reducing space and potential, and is a key field for China to realize energy saving and emission reduction and low-carbon development. The application of industrial waste slag as a mixing material to produce cement has achieved good application results, significantly reducing resource and energy consumption and carbon dioxide emission in the cement production process, reducing the cost of cement production, and eliminating environmental pollution caused by industrial waste slag, and has been actively promoted by cement enterprises.

[0003] With the continuous improvement of the application technology of industrial waste slag in cement, the types of industrial waste slag are increasing, and the mixing amount is increasing. The production process of industrial waste slag determines that it contains a large amount of water (more than 20% or even higher) in its composition, such as slag, which is the residue produced in the process of smelting pig iron and is obtained by water quenching, lithium slag, which is the waste slag produced in the process of producing lithium carbonate by using sulfuric acid method, desulfurization gypsum, which is obtained by reacting flue gas containing SO2 with lime slurry, and the like. However, the moisture of the raw material entering the mill has a significant influence on the cement ball mill grinding process. When the moisture is too large, the phenomenon of paste ball and paste grinding will occur. When the comprehensive moisture of the raw material entering the mill increases by 1%, the output of the ball mill will decrease by 10%. When the comprehensive moisture of the raw material entering the mill exceeds 3%, the output of the cement mill will be significantly reduced, and even serious adhesion in the mill will occur, which cannot be produced. Therefore, the moisture in the industrial waste slag limits its application as a cement mixing material to some extent. In the actual production process, the industrial waste slag is dried to reduce the moisture, but this method not only has high energy consumption but also low efficiency.

[0004] Cement grinding aids have been widely used by cement companies as an additive to improve grinding efficiency and grinding conditions. However, currently, grinding aids mainly achieve their dispersion effect on cement particles by shielding the charges generated by bond breaking during the grinding process and eliminating static electricity. When the moisture content of cement raw materials is high, electrostatic adsorption is less, and existing grinding aids are difficult to exert their effect. The main grinding aid components of existing grinding aids are polyol amines and polyols, which contain a large number of hydroxyl groups in their molecules. After being adsorbed on the surface of cement particles, the hydroxyl groups will further absorb moisture from the raw materials, which will in turn aggravate the adverse effects of moisture on cement grinding. In addition, the polyol amine component in existing grinding aids will promote cement hydration, causing cement to prehydrate after absorbing water, reducing cement strength. Therefore, existing grinding aids cannot solve the problems of ball grinding and reduced yield during ball milling of raw materials with high moisture content, as well as reduced strength during application.

[0005] CN 104045257 A discloses a high-moisture cement grinding aid. The raw materials are: 40-55% polyol grinding aid mother liquor, 0.01-0.5% acrylic acid, 1-10% ammonium sulfate, 0.02-0.05% sodium dodecylbenzenesulfonate, 2-5% triethanolamine, 1-5% sugarcane slag liquid, and the balance water, totaling 100%; all percentages are by mass. The polyol grinding aid mother liquor is prepared by adding 2 parts maleic anhydride and 1 part polyol to a reaction kettle, mixing them evenly, and reacting them at 100°C for 3 hours to synthesize the polyol grinding aid mother liquor. This patent uses acid to modify the polyol and combines it with sodium dodecylbenzenesulfonate to improve the fluidity of cement powder. However, the raw materials used are all hydrophilic, which cannot effectively isolate moisture from cement particles, resulting in limited effectiveness.

[0006] CN 116023060 A discloses an anti-moisture absorption and caking cement grinding aid. Its main grinding aid components include N-tert-butyloxycarbonyldiethanolamine, an alcoholamine compound, and a glycol compound, with water as the solvent. This patent utilizes N-tert-butyloxycarbonyldiethanolamine to adsorb onto the surface of cement particles at one end, while the hydrophobicity of the ester group and polymethyl groups at the other end isolates moisture, thereby improving the cement's resistance to moisture absorption and caking. However, the ester group in the N-tert-butyloxycarbonyldiethanolamine structure is unstable, and the substance itself has limited hydrophobicity, resulting in limited improvement in the grinding process of high-moisture cement admixtures.

[0007] CN 116986844 A discloses a grinding aid for improving the hygroscopicity of cement. The grinding aid comprises the following components by mass percentage: 6% to 15% of a polyol mono-fatty acid ester compound, 12% to 48% of a polyol amine mono-fatty acid ester compound, 1% to 6% of a gypsum dehydration inhibitor, 3% to 7% of a grinding aid and film-forming agent, 0.5% to 3.0% of a titanate coupling agent, 0.1% to 0.5% of a defoaming agent, and the remainder being water. The invention utilizes the hydrophobicity of the ester groups and long alkyl chains in the side chains of the polyol mono-fatty acid ester compound and the polyol amine mono-fatty acid ester compound to improve the hygroscopicity of cement. However, the ester groups are easily decomposed during the grinding of cement with high moisture content, resulting in limited effectiveness.

[0008] CN 114634322 A provides a cement strength anti-degradation agent, its preparation method, and application. The raw materials are: 10%-15% polyacid ester, 5%-10% polyphosphate, 0.1%-0.5% SAP superabsorbent resin, 3%-8% sulfonate, 5%-12% alcoholamine, and the balance is water. The invention utilizes the hydrophilic groups and cross-linked polymer electrolytes contained in SAP superabsorbent resin, which has a high water absorption capacity, absorbing water hundreds to thousands of times its own weight, and has excellent water retention. Once it absorbs water and expands to form a hydrogel, it is difficult to separate the water even under pressure. Differential thermal analysis shows that 50% of the water absorbed by the superabsorbent resin remains enclosed in the gel network at temperatures above 150°C. When added to cement, the agent effectively absorbs free water present in the cement and encloses it in the gel network, thereby preventing prehydration reactions between active substances in the cement and free water, ensuring that the cement strength will not degrade. However, SAP super absorbent resin will absorb water and swell. If it remains in cement, it will cause instability in the structure of the hydration product and have an adverse effect on the performance of the cement.

[0009] Existing technologies cannot stably enable cement to resist high moisture content in admixtures, nor can they effectively separate cement from moisture. They cannot solve the problems of high-moisture content raw materials causing ball sticking during ball milling, resulting in reduced output and decreased strength during application. Summary of the Invention

[0010] The purpose of the present invention is to provide a grinding aid and a preparation method thereof, which improves the ability of the cement particle surface to resist moisture in the admixture through component matching optimization and surface modification, while effectively accelerating the absorption and volatilization of moisture in the admixture, effectively improving the fluidity of the cement powder in the mill, and compensating for the inability of existing grinding aids to solve the problems of high-moisture content raw materials causing ball sticking during ball milling, reduced output, and reduced strength during application.

[0011] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0012] A cement grinding aid comprises the following components by mass: 300-500 parts of fly ash, 15-40 parts of an organic grinding aid component, 2-8 parts of an inorganic grinding aid component, 1-3 parts of a dehydrating agent, 3-6 parts of a water absorbent, 2-5 parts of hydrophobic silicon dioxide, and 8-13 parts of biterminal silane polyethylene glycol.

[0013] According to the above solution, the fly ash is Class I fly ash, and the glass bead content is greater than 60wt%.

[0014] According to the above scheme, the organic grinding aid component is composed of polyol amine, polyol, and polyphenyl alcohol ether; the molar ratio of the polyol amine and polyol is 1:(0.2-0.5), and the ratio of the sum of the molar amounts of the polyol amine and polyol to the molar amount of the polyphenyl alcohol ether is 1:1.

[0015] According to the above scheme, the polyol amine is one of triethanolamine, diethanol monoisopropanolamine, hydroxyethyl diisopropanolamine, triisopropanolamine, N,N,N,N-tetrakis (2-hydroxyethyl) ethylenediamine or any mixture thereof.

[0016] According to the above scheme, the polyol is one of glycerol, 1,2,4-butanetriol, 1,2,3-butanetriol, and threitol, or any mixture thereof.

[0017] According to the above scheme, the polyphenyl alcohol ether is one of hydroquinone dihydroxyethyl ether and hydroquinone diisopropyl alcohol ether or any mixture thereof.

[0018] According to the above scheme, the inorganic grinding aid component is one of sodium tripolyphosphate and sodium hexametaphosphate or any mixture thereof.

[0019] According to the above scheme, the dehydrating agent is one of isobutanol, isopropanol, tert-butanol or any mixture thereof.

[0020] According to the above scheme, the water absorbent is ((5-carboxyl-1H-pyrazole-3-carbonyl)oxy)(hydroxy)aluminum (III), MOF-303 (AL) metal organic framework, with a specific surface area of ​​800-1200m 2 / g.

[0021] According to the above scheme, the hydrophobic silica is prepared by treating hydrated silica with high hydrogen content silicone oil, the treatment method is surface coating, and the particle size range is 5-15 μm.

[0022] According to the above scheme, the molecular weight of the bi-terminal silane polyethylene glycol is 400 to 2000 g / mol.

[0023] The preparation method of the above-mentioned cement grinding aid comprises the following steps:

[0024] An organic grinding aid component, an inorganic grinding aid component, a dehydrating agent, a water absorbent, hydrophobic silica, and bi-terminal silane polyethylene glycol are slowly added to fly ash in sequence, and then the mixture is placed in a mixer and mixed for 60 to 120 minutes to obtain the cement grinding aid.

[0025] The application of the above cement grinding aid in the ball mill grinding process of high-moisture mixed material cement.

[0026] According to the above solution, the total moisture content of the cement raw materials entering the mill is 2-4 wt%.

[0027] According to the above solution, the dosage of the cement grinding aid is 0.3-0.5 wt% of the mass of the raw materials fed into the mill.

[0028] This invention uses fly ash as a carrier for cement grinding aids, effectively and evenly loading components with varying physical and chemical properties, ensuring uniformity during application. Fly ash containing a large number of glass microspheres is selected. The lubricating effect of the glass microspheres increases the fluidity of the cement raw materials during grinding, increasing the material flow rate within the mill and helping the air inside the mill to remove moisture and discharge it out of the mill.

[0029] Polyolamines and polyols are excellent cement grinding aids, but the multiple hydroxyl groups in their structures combine with water in the cement raw materials, resulting in their inability to effectively aid grinding in high-moisture cement raw materials. The present invention uses polyphenyl alcohol ethers in combination with polyolamines and polyols containing more than 3 hydroxyl groups. The hydroxyl groups in the polyphenyl alcohol ether structure can combine with the polyolamines and polyols, allowing them to be adsorbed on the surface of cement particles. The benzene ring has good hydrophobicity and rigidity, which can, on the one hand, alleviate the adverse effects of the hydrophilicity of polyolamines and polyols. On the other hand, the rigidity of the benzene ring structure can enhance the grinding effect and the stability of the adsorption layer.

[0030] Sodium tripolyphosphate and sodium hexametaphosphate can effectively aid grinding by binding to the broken bonds formed on the surface of cement raw materials during grinding. The repulsion of like charges prevents particles from approaching and agglomerating, thus providing a good grinding aid. Furthermore, sodium tripolyphosphate and sodium hexametaphosphate can increase the surface energy of the mineral phase of cement raw material particles. This higher surface energy helps hydrophobic silica and silane polyethylene glycol adsorb to the mineral phase of cement raw material particles, enhancing their effectiveness.

[0031] The present invention adopts small molecule alcohol as a dehydrating agent. Small molecule alcohol has a low surface tension and can improve the ability of other components to be adsorbed on the surface of the mineral phase of the cement raw material particles; the grinding temperature of the ball mill is generally 80-120°C. The small molecule alcohol can bond with water to lower the boiling point of water, thereby accelerating the volatilization of water in the cement raw materials, helping the water to be discharged from the mill, and reducing the adverse effects of water on the grinding process.

[0032] MOF-303(Al) is selected as the water-absorbing material. It has good water absorption in low humidity environment and can effectively absorb moisture in cement grinding environment. In addition, MOF-303(Al) can absorb water from cement hydration. 3+ Coordination occurs, accelerating Al 3+ Dissolution promotes cement hydration and improves the strength of cement paste; MOF-303 (Al) has reversible water absorption and exists in cement after grinding. When cement is added with water to form cement paste, the pressure difference formed by the change in water content inside and outside the hydration product can cause MOF-303 (Al) to release water. It will not absorb water and expand to form an unstable gel structure like SAP super absorbent resin.

[0033] Hydrophobic silica can isolate moisture from contact with cement particles during cement grinding, thereby improving the cement's water resistance. It can undergo hydration reaction in the strong alkaline environment generated by cement hydration, filling the gaps between hydration products, improving hydration density and thus increasing cement strength.

[0034] Silane polyethylene glycol significantly improves the wettability of organic grinding aid components and the surface of cement particles. The silane structure also bonds with hydrophobic silica, improving its adsorption capacity to cement particles and effectively forming an adsorption film. This enhances the ability to isolate water from the cement particles, preventing the phenomenon of sticky grinding caused by water adhering to the cement particle surface during grinding. A silane-polyethylene glycol-silane with a molecular weight of 400-2000 g / mol is recommended. If the molecular weight is too low, the polyethylene glycol chain segment is too short, which is not conducive to the formation of an adsorption film. If the molecular weight is too high, the polyethylene glycol chain segment is too long, resulting in excessive hydrophilicity and poor isolation of water from the cement particles.

[0035] The present invention utilizes fly ash as a carrier to effectively and evenly distribute the various components therein. Inorganic grinding aid components are utilized to improve the surface energy of cement particles and enhance the adsorption capacity of other components; under the action of small molecule dehydrating agents to improve surface tension and dehydrating agents such as silane polyethylene glycol to improve adsorption capacity, organic grinding aid components and hydrophobic silica work together to stabilize and form a moisture isolation film on the surface of cement particles; the isolated moisture is rapidly discharged under the action of the dehydrating agent and is absorbed by the water absorbent at the same time. The synergistic action of the different components effectively improves the phenomenon of high-moisture content raw materials being mushy during ball milling, resulting in reduced yield and strength. At the same time, the various components not only have no adverse effect on cement hydration, but can promote cement hydration, enhance the density of cement water products, and effectively enhance cement strength.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The raw materials of the cement grinding aid provided by the invention can be obtained through commercial channels, the preparation method is simple, and industrialization can be realized.

[0038] The cement grinding aid provided by the application is beneficial to improving the adsorption capacity of organic matter on the surface of cement particles by improving the surface energy, surface tension and bridging capacity.

[0039] The cement grinding aid provided by the application improves the hydrophilicity of the existing polyol amine and polyol substance, and improves the grinding aid effect in the high-moisture cement raw material ball grinding process.

[0040] The organic grinding component, hydrophobic silicon dioxide and silane polyethylene glycol in the cement grinding aid provided by the application jointly act on the surface of the cement particles to form a water isolation film, effectively improving the moisture resistance of the cement particles in the high-moisture grinding environment.

[0041] The dehydrating agent in the cement grinding aid provided by the application can facilitate the moisture discharge of the cement raw material, and the water absorbing agent can effectively absorb the moisture in the cement raw material, effectively reducing the moisture of the cement raw material in the grinding process.

[0042] The different components of the cement grinding aid provided by the application effectively solve the problems of paste balling, reduced yield and strength reduction of high-moisture content raw materials in the ball grinding process.

[0043] The components of the cement grinding aid provided by the application not only have no adverse effect on cement hydration, but also can promote cement hydration and improve the compactness of cement hydration products, effectively improving the strength of the cement. DETAILED DESCRIPTION

[0044] The following examples further illustrate the technical solutions of the application, but are not intended to limit the protection scope of the application. The following specific examples are only a part of the preferred embodiments of the application, rather than all the embodiments. Based on the examples in the application, modifications, substitutions and improvements made by those skilled in the art without creative labor are within the protection scope of the application.

[0045] The specific embodiments provide the source of the test material, which can be obtained through commercial channels if not otherwise specified.

[0046] The fly ash in the specific embodiments is obtained from Huanggang Dabieshan Power Generation Co., Ltd., meets the requirements of national standard grade I fly ash, and the content of glass beads is 73%.

[0047] The polybasic phenyl alcohol ether in the specific embodiments is obtained through commercial channels, and the manufacturer is Zhongshan Dixin Chemical Co., Ltd.

[0048] The water absorbing agent MOF-303(Al) in the specific embodiments is obtained through commercial channels, and the manufacturer is Xi'an Qiyue Biological Technology Co., Ltd. The specific surface area is 900 m 2 / g.

[0049] The hydrophobic silicon dioxide is commercially available from Anhui Sailikeli Silicon Material Co., Ltd., model SH-520, particle size range 5-12 pm.

[0050] The silane-polyethylene glycol-silane (double-end silane polyethylene glycol) is commercially available from Xi'an Deerta Biological Technology Co., Ltd.

[0051] The following examples 1-10 correspond to the organic grinding aid components used. The polyol amine, polyol, polyphenyl alcohol ether were weighed according to the molar ratio in Table 1, and mixed uniformly to obtain the organic grinding aid component.

[0052] Table 1

[0053] Example 1 2 3 4 5 6 7 8 9 10 triethanolamine 1.0 0.1 0.3 0.1 Diethanol monoisopropanolamine 1.0 0.9 0.5 0.4 0.1 0.3 Hydroxyethyl diisopropanolamine 1.0 0.5 0.9 0.3 0.2 0.5 triisopropanolamine 1.0 0.1 0.7 0.1 Glycerol 0.2 0.2 0.1 0.1 0.5 1,2,4-Butanetriol 0.5 0.1 0.1 0.1 1,2,3-Butanetriol 0.3 0.1 0.2 0.1 0.4 Threitol 0.4 0.1 Hydroquinone dihydroxyethyl ether 1.2 0.7 0.1 1.2 0.7 1.2 1.3 Hydroquinone diisopropyl ether 1.5 0.6 1.3 0.1 0.7 1.5 1.1

[0054] Example 1

[0055] To 300 parts of fly ash, 15 parts of organic grinding aid component, 2 parts of sodium tripolyphosphate, 1 part of isobutyl alcohol, 6 parts of MOF-303(Al), 5 parts of hydrophobic silicon dioxide, 8 parts of silane-polyethylene glycol-silane with a molecular weight of 400 g / mol were added slowly in turn, and then mixed in a mixer for 60 min to obtain the cement grinding aid.

[0056] Example 2

[0057] To 500 parts of fly ash, 40 parts of organic grinding aid component, 8 parts of sodium hexametaphosphate, 3 parts of isopropyl alcohol, 3 parts of MOF-303(Al), 2 parts of hydrophobic silicon dioxide, 13 parts of silane-polyethylene glycol-silane with a molecular weight of 600 g / mol were added slowly in turn, and then mixed in a mixer for 120 min to obtain the cement grinding aid.

[0058] Example 3

[0059] To 300 parts of fly ash, 40 parts of organic grinding aid component, 8 parts of sodium tripolyphosphate, 3 parts of tert-butyl alcohol, 3 parts of MOF-303(Al), 2 parts of hydrophobic silicon dioxide, 13 parts of silane-polyethylene glycol-silane with a molecular weight of 800 g / mol were added slowly in turn, and then mixed in a mixer for 68 min to obtain the cement grinding aid.

[0060] Example 4

[0061] To 500 parts of fly ash, 15 parts of organic grinding aid component, 2 parts of sodium hexametaphosphate, 1 part of isobutyl alcohol, 6 parts of MOF-303(Al), 5 parts of hydrophobic silicon dioxide, 8 parts of silane-polyethylene glycol-silane with a molecular weight of 1000 g / mol were added slowly in turn, and then mixed in a mixer for 76 min to obtain the cement grinding aid.

[0062] Example 5

[0063] To 469 parts of fly ash, 26 parts of organic grinding aid components, 3 parts of sodium hexametaphosphate, 1 part of isobutanol, 1 part of isopropanol, 1 part of tert-butanol, 4 parts of MOF-303 (Al), 3 parts of hydrophobic silica, and 13 parts of silane-polyethylene glycol-silane with a molecular weight of 1200 g / mol were slowly added in sequence, and then placed in a mixer and mixed for 111 minutes to obtain the cement grinding aid.

[0064] Example 6

[0065] 33 parts of an organic grinding aid component, 6 parts of sodium hexametaphosphate, 2 parts of isobutanol, 4 parts of MOF-303 (Al), 4 parts of hydrophobic silica, and 10 parts of silane-polyethylene glycol-silane with a molecular weight of 600 g / mol were slowly added to 497 parts of fly ash in sequence, and then placed in a mixer and mixed for 102 minutes to obtain the cement grinding aid.

[0066] Example 7

[0067] To 400 parts of fly ash, 38 parts of organic grinding aid components, 4 parts of sodium tripolyphosphate, 4 parts of sodium hexametaphosphate, 3 parts of isopropanol, 3 parts of MOF-303 (Al), 5 parts of hydrophobic silica, and 10 parts of silane-polyethylene glycol-silane with a molecular weight of 800 g / mol were slowly added in sequence, and then placed in a mixer and mixed for 98 minutes to obtain the cement grinding aid.

[0068] Example 8

[0069] To 348 parts of fly ash, 21 parts of organic grinding aid components, 5 parts of sodium tripolyphosphate, 1 part of sodium hexametaphosphate, 1 part of isobutanol, 6 parts of MOF-303 (Al), 3 parts of hydrophobic silica, and 12 parts of silane-polyethylene glycol-silane with a molecular weight of 1000 g / mol were slowly added in sequence, and then placed in a mixer and mixed for 82 minutes to obtain the cement grinding aid.

[0070] Example 9

[0071] To 425 parts of fly ash, 17 parts of organic grinding aid components, 2 parts of sodium tripolyphosphate, 4 parts of sodium hexametaphosphate, 1 part of isobutanol, 2 parts of isopropanol, 6 parts of MOF-303 (Al), 5 parts of hydrophobic silica, and 11 parts of silane-polyethylene glycol-silane with a molecular weight of 400 g / mol were slowly added in sequence, and then placed in a mixer and mixed for 79 minutes to obtain the cement grinding aid.

[0072] Example 10

[0073] To 373 parts of fly ash, 39 parts of organic grinding component, 7 parts of sodium tripolyphosphate, 2 parts of isobutyl alcohol, 1 part of tert-butyl alcohol, 4 parts of MOF-303(Al), 4 parts of hydrophobic silicon dioxide, 9 parts of silane-polyethylene glycol-silane with a molecular weight of 1200 g / mol were added slowly in turn, and then mixed in a mixer for 91 min to obtain the cement grinding aid.

[0074] Comparative Example 1

[0075] Example 1 was repeated, except that no hydroquinone dihydroxyethyl ether was added during the preparation of the organic grinding component, and other conditions were unchanged to obtain mixture 1.

[0076] Comparative Example 2

[0077] Example 2 was repeated, except that no sodium tripolyphosphate was added, and other conditions were unchanged to obtain mixture 2.

[0078] Comparative Example 3

[0079] Example 3 was repeated, except that no isobutyl alcohol was added, and other conditions were unchanged to obtain mixture 3.

[0080] Comparative Example 4

[0081] Example 4 was repeated, except that no MOF-303(Al) was added, and other conditions were unchanged to obtain mixture 4.

[0082] Comparative Example 5

[0083] Example 5 was repeated, except that no silane-polyethylene glycol-silane was added, and other conditions were unchanged to obtain mixture 5.

[0084] Comparative Example 6

[0085] Example 6 was repeated, except that glycol was used instead of glycerol, 1,2,3-butanetriol, 1,2,4-butanetriol, and threitol, and other conditions were unchanged to obtain mixture 6.

[0086] Comparative Example 7

[0087] Example 7 was repeated, except that acrylic acid-□ acrylamide copolymer SAP superabsorbent resin was used instead of MOF-303(Al), and other conditions were unchanged to obtain mixture 7.

[0088] Comparative Example 8

[0089] Example 8 was repeated, except that silane-polyethylene glycol-silane with a molecular weight of 200 g / mol was used instead of silane-polyethylene glycol-silane with a molecular weight of 1000 g / mol, and other conditions were unchanged to obtain mixture 8.

[0090] Comparative Example 9

[0091] Example 9 was repeated, except that an equal amount of silane-polyethylene glycol-silane with a molecular weight of 3000 g / mol was used to replace the silane-polyethylene glycol-silane with a molecular weight of 400 g / mol, while other conditions remained unchanged, to obtain a mixture 9.

[0092] The grinding aids for improving cement hygroscopicity prepared in Examples 1 to 10, the mixtures prepared in Comparative Examples 1 to 9, and a commercially available cement grinding aid with triethanolamine and diethylene glycol as main raw materials were tested and evaluated.

[0093] Referring to the test method in GB / T 26748-2011 "Cement Grinding Aids," 5 kg of various cement raw materials were added to a test mill using a P.O. 42.5 cement mix ratio: 80% clinker, 4% slag, 5% lithium slag, 5% coal slag, and 5% desulfurized gypsum. The slag had a moisture content of 18.3%, 19.9% ​​for lithium slag, 20.5% for coal slag, and 19.2% for desulfurized gypsum, resulting in a combined moisture content of 3.9%. Before grinding, a cement grinding aid or mixture was added at a rate of 0.4% to the raw cement raw materials. The grinding time was fixed at 25 minutes to obtain a P.O. 42.5 cement sample. After grinding, the conditions inside the ball mill were observed and recorded. The angle of repose of the cement powder exiting the mill was measured using an angle-of-repose meter to characterize its flowability. The fineness of the out-of-grind cement was tested with reference to GB / T 1345-2005, "Test Method for Cement Fineness - Sieve Analysis Method." The specific surface area of ​​the out-of-grind cement was tested with reference to GB / T 8074-2008, "Determination of Specific Surface Area of ​​Cement - Blaine Method." The strength of the cement was tested with reference to GB / T 17671-1999, "Test Method for Cement Mortar Strength (ISO Method)." A comparative evaluation was conducted using the grinding aids prepared in Examples 1 to 10, the mixtures prepared in Comparative Examples 1 to 9, a commercially available cement grinding aid, and a blank sample without cement grinding aid. The results are shown in Tables 2, 3, and 4.

[0094] Table 2

[0095]

[0096]

[0097] As shown in Table 2, the grinding aid prepared by the present invention effectively improves the ball-sticking and grinding phenomenon of high-moisture cement raw materials during ball milling, compared with a blank control without grinding aid, a commercially available cement grinding aid, and Comparative Examples 1 to 9. Furthermore, the repose angle of the cement powder after milling is reduced, and the cement powder has better fluidity. In Comparative Examples 1 to 9, replacing or omitting any of the components failed to achieve the same effect, further demonstrating the synergistic effect between the components of the grinding aid prepared by the present invention.

[0098] Table 3

[0099] serial number Specific surface area / m 2 / kg 80μm sieve residue / % 45μm sieve residue / % Blank group 338.6 4.3 18.6 Commercially available cement grinding aids 336.9 4.7 19.6 Comparative Example 1 348.6 3.6 16.3 Comparative Example 2 342.1 3.3 15.8 Comparative Example 3 341.2 3.1 17.6 Comparative Example 4 345.6 3.0 15.3 Comparative Example 5 343.2 3.5 17.2 Comparative Example 6 340.1 3.5 16.5 Comparative Example 7 339.9 3.4 16.3 Comparative Example 8 348.7 3.8 15.9 Comparative Example 9 345.6 1.9 16.4 Example 1 363.1 1.6 12.0 Example 2 365.2 1.0 11.3 Example 3 369.6 1.2 10.8 Example 4 359.7 1.2 10.6 Example 5 364.8 1.5 10.5 Example 6 370.3 1.6 11.8 Example 7 361.3 1.1 10.9 Example 8 366.6 1.6 9.6 Example 9 365.2 1.5 11.2 Example 10 367.0 1.4 11.0

[0100] As shown in Table 3, the grinding aid prepared by the present invention significantly increased the specific surface area of ​​cement prepared from high-moisture cement raw materials and reduced the 80μm and 45μm sieve residues compared to a blank control without grinding aid, a commercially available cement grinding aid, and Comparative Examples 1 to 9. This compensates for the poor grinding effect of commercially available cement grinding aids in high-moisture cement raw materials. In Comparative Examples 1 to 9, replacing or omitting any of the components failed to achieve the same effect, further demonstrating the synergistic effect between the components of the grinding aid prepared by the present invention.

[0101] Table 4

[0102]

[0103] As shown in Table 4, the grinding aid prepared in accordance with the present invention significantly increased the 3-day and 28-day flexural and compressive strengths of cement compared to a blank control without grinding aid, a commercially available cement grinding aid, and Comparative Examples 1 to 9. This significantly improves the flexural and compressive strengths of cement at 3 and 28 days, overcoming the shortcomings of commercially available cement grinding aids in reinforcing high-moisture cement raw materials. In Comparative Examples 1 to 9, replacing or omitting any of the components failed to achieve the same effect, further demonstrating the synergistic strengthening effect between the components of the grinding aid prepared in accordance with the present invention.

Claims

1. A cement grinding aid, characterized in that The composition is as follows by mass: 300-500 parts of fly ash, 15-40 parts of organic grinding aid component, 2-8 parts of inorganic grinding aid component, 1-3 parts of dehydrating agent, 3-6 parts of water absorbent, 2-5 parts of hydrophobic silica, and 8-13 parts of bifunctional silane polyethylene glycol; The organic grinding aid component is composed of polyol amine, polyol, and polyphenyl alcohol ether; the molar ratio of the polyol amine and the polyol is 1:(0.2-0.5), and the ratio of the sum of the molar amounts of the polyol amine and the polyol to the molar amount of the polyphenyl alcohol ether is 1:1; The inorganic grinding aid component is one of sodium tripolyphosphate and sodium hexametaphosphate or any mixture thereof; The dehydrating agent is one of isobutanol, isopropanol, tert-butanol or any mixture thereof; The water absorbent is MOF-303 (AL) metal organic framework with a specific surface area of ​​800-1200m 2 / g.

2. Cement grinding aid as claimed in claim 1, characterized in that The fly ash is Class I fly ash, and the glass bead content is greater than 60 wt %.

3. Cement grinding aid as claimed in claim 1, is characterized in that The polyol amine is one of triethanolamine, diethanol monoisopropanolamine, hydroxyethyl diisopropanolamine, triisopropanolamine, and N,N,N,N-tetrakis (2-hydroxyethyl) ethylenediamine, or any mixture thereof; the polyol is one of glycerol, 1,2,4-butanetriol, 1,2,3-butanetriol, and threitol, or any mixture thereof; the polyphenyl alcohol ether is one of hydroquinone dihydroxyethyl ether and hydroquinone diisopropyl alcohol ether, or any mixture thereof.

4. cement grinding aid as claimed in claim 1, characterized in that The hydrophobic silica particle size ranges from 5 to 15 μm; the bimodal silane polyethylene glycol has a molecular weight of 400 to 2000 g / mol.

5. The method for preparing a cement grinding aid according to any one of claims 1 to 4, characterized in that The following steps are involved: An organic grinding aid component, an inorganic grinding aid component, a dehydrating agent, a water absorbent, hydrophobic silica, and bi-terminal silane polyethylene glycol are slowly added to fly ash in sequence, and then the mixture is placed in a mixer and mixed for 60 to 120 minutes to obtain the cement grinding aid.

6. Use of the cement grinding aid according to any one of claims 1 to 4 in a high-moisture cement ball milling process, characterized in that The total moisture content of the cement raw materials entering the mill is 2-4 wt%.

7. The application of the cement grinding aid in the high-moisture cement ball milling process as claimed in claim 6, characterized in that The dosage of the cement grinding aid is 0.3-0.5 wt% of the mass of the raw materials fed into the mill.

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