Cement anti-cracking grinding aid for chromium ion curing and preparation method thereof

Abstract

The invention discloses a cement anti-cracking grinding aid for chromium ion curing and a preparation method thereof, and belongs to the technical field of building materials. The chromium ion cured cement anti-cracking grinding aid is prepared from the following raw materials in parts by weight: 3 to 10 parts of chromium ion cured microspheres, 9 to 18 parts of modified cellulose ether, 20 to 35 parts of sorbitol, 3 to 10 parts of diethanolisopropanolamine, 15 to 30 parts of aluminum sulfate, 50 to 70 parts of deionized water, 10 to 20 parts of polymeric polyol and 2 to 8 parts of sodium sulfate. The chromium ion curing microspheres are innovatively added into the grinding aid, so that the grinding aid not only has excellent hexavalent chromium reduction stability, but also can effectively cure the chromium element, and meanwhile, the problem of equipment corrosion is successfully solved. In addition, the special functional component modified cellulose ether is introduced, so that the shrinkage cracking of the cement is reduced, and the anti-cracking performance of the cement is improved. According to the grinding aid disclosed by the invention, the chromium ion curing microspheres and the modified cellulose ether are added, so that the curing of chromium ions and the remarkable improvement of the mechanical property of cement are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a cement anti-cracking grinding aid for chromium ion solidification and a preparation method thereof. Background Art

[0002] During cement production, since the raw materials contain a certain amount of chromium, the raw materials will be oxidized into hexavalent chromium and dissolved in the cement clinker during high-temperature firing. The refractory materials used in cement kilns also contain a certain amount of chromium ions. Water-soluble hexavalent chromium will also be produced during cement firing and grinding. Hexavalent chromium is highly reactive, highly soluble, and extremely toxic and carcinogenic, and is a Class 1 carcinogen. Cement plays an irreplaceable role in our daily life and urban construction, so the hexavalent chromium content in cement must be strictly controlled. The conventional method is to add ferrous sulfate during cement grinding to reduce hexavalent chromium to trivalent chromium to reduce its water solubility, thereby reducing its chromium ion content. However, since cement is ground at 80-100°C, the added ferrous sulfate will be oxidized into ferric sulfate, resulting in poor chromium ion solidification ability, and ferrous sulfate has a certain corrosiveness, which will corrode the equipment during grinding. In addition, silicate cement will shrink during the hydration process, causing cement cracking and negatively affecting the strength of cement.

[0003] Since it is difficult to completely avoid the natural presence of chromium in raw materials during cement production, high-temperature calcination will promote the oxidation of trivalent chromium to produce highly toxic hexavalent chromium, and the control effect is limited only at the raw material end; and the traditional method of directly adding ferrous sulfate has obvious disadvantages. Therefore, in response to the above problems, a cement anti-cracking grinding aid for chromium ion solidification is developed to effectively reduce the hexavalent chromium content and solidify the chromium ions, while improving the strength and crack resistance of cement. Summary of the invention

[0004] The object of the present invention is to provide a cement anti-cracking grinding aid for chromium ion solidification, which can effectively reduce the hexavalent chromium content and solidify the chromium ions, while improving the strength and crack resistance of cement.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] A cement anti-cracking grinding aid for chromium ion solidification comprises the following raw materials in parts by weight: 3-10 parts of chromium ion solidification microspheres, 9-18 parts of modified cellulose ether, 20-35 parts of sorbitol, 3-10 parts of diethanol monoisopropanolamine, 15-30 parts of aluminum sulfate, 50-70 parts of deionized water, 10-20 parts of polymerized polyols, and 2-8 parts of sodium sulfate.

[0007] Furthermore, the preparation method of the modified cellulose ether is:

[0008] (1) Dispersing cellulose ether in anhydrous ethanol, ultrasonically treating for 30 minutes, adding cardanol and stirring evenly, then adding catalyst triethylamine and reacting at 60° C. for 6 hours. After the reaction is completed, washing with ethanol three times to remove unreacted cardanol and catalyst, and vacuum drying to obtain hydrophobically modified cellulose ether;

[0009] (2) Dissolve cocamidopropyl betaine in deionized water, add hydrophobically modified cellulose ether to prepare a 5% suspension, and ultrasonically treat for 30 minutes to ensure sufficient dispersion. Add polyethylene glycol diglycidyl ether and stir evenly, react at 50° C. for 4 hours, wash with deionized water three times after the reaction, and freeze-dry to obtain modified cellulose ether.

[0010] Furthermore, in the step (1), the molar ratio of cellulose ether to cardanol is 1:1.2; the amount of triethylamine added is 1% of the mass of cardanol; and the total mass ratio of anhydrous ethanol to cellulose ether and cardanol is 5:1.

[0011] Furthermore, in the step (2), the amount of polyethylene glycol diglycidyl ether added is 5% of the weight of the hydrophobically modified cellulose ether; and the amount of cocamidopropyl betaine added is 0.5% of the weight of deionized water.

[0012] Furthermore, the chromium ion-cured microspheres include the following raw materials in parts by weight:

[0013] 5-30 parts of activated carbon, 8-20 parts of ferrous sulfate, 0.01-0.03 parts of magnesium trifluoromethanesulfonate, 40-85 parts of deionized water, 100 parts of anhydrous ethanol, 8-25 parts of ethyl orthosilicate, 0.01-0.32 parts of surfactant, and 2-13 parts of catalyst.

[0014] Furthermore, the preparation method of the chromium ion-cured microspheres is:

[0015] S1: Grind the activated carbon, select the activated carbon with a particle size less than 1 μm and dry it in an oven at 105°C;

[0016] S2: adding ferrous sulfate and magnesium trifluoromethanesulfonate to deionized water, stirring evenly to obtain ferrous sulfate solution A, adding the activated carbon dried in step S1 to the ferrous sulfate solution A, ultrasonically dispersing for 10 minutes, and filtering to obtain activated carbon B adsorbing ferrous sulfate and magnesium trifluoromethanesulfonate;

[0017] S3: Add activated carbon B and surfactant to anhydrous ethanol and stir for 3 minutes, then continue to add pH adjuster and ammonia water, ultrasonically treat for 5 minutes, then drop 15 parts of tetraethyl orthosilicate at a speed of 400 r / min to react for 5 hours, and after the reaction is completed, filter to obtain chromium ion-cured microspheres.

[0018] Furthermore, in the preparation method of the chromium ion-cured microspheres, in step S3, a pH regulator is added until the pH of the solution is 8-10; the regulator is a sodium hydroxide solution.

[0019] A method for preparing a cement anti-cracking grinding aid for chromium ion solidification comprises the following steps:

[0020] Aluminum sulfate is added into deionized water and stirred until completely dissolved; sorbitol and polymerized polyol are added into the aluminum sulfate solution and stirred evenly; modified cellulose ether is slowly added and stirred continuously until completely dissolved to form a uniform solution; chromium ion-cured microspheres and diethanol monoisopropanolamine are added and stirred evenly; finally, sodium sulfate is added and stirred until completely dissolved; after stirring evenly, a cement anti-cracking grinding aid is obtained.

[0021] The raw materials used in the present invention are all commercially available.

[0022] The cement grinding aid of the present invention adds cellulose ether modified by cardanol and polyethylene glycol diglycidyl ether. Firstly, the long-chain alkyl structure of cardanol significantly enhances the hydrophobicity of nano-cellulose ether, and the epoxy group reacts with the hydroxyl group of cellulose ether to form a stable chemical bond, thereby preventing the hydrophobic group from falling off. Then, the polyethylene glycol diglycidyl ether enables the cellulose ether to form a three-dimensional network structure, thereby significantly improving the water retention and mechanical properties. Meanwhile, the cross-linked structure formed by the polyethylene glycol diglycidyl ether and the cellulose ether enhances the stability of the cellulose ether in cement paste, reduces water evaporation, and reduces the risk of shrinkage and cracking.

[0023] The aluminum sulfate added to the grinding aid of the present invention will participate in the hydration process of cement, reducing the driving force for cement cracking. During the early hydration of cement, calcium ions and hydroxides in the cement will react with aluminum sulfate to generate an expansive hydration product, calcium sulfonate, to compensate for the shrinkage of cement during hydration. When cement shrinks, the needle-shaped calcium sulfonate will play a bridging role, offsetting part of the shrinkage stress during cement hydration, and reducing the driving force for cement cracking. Since cement shrinkage is suppressed, cement cracking is reduced, and the strength of cement is significantly improved.

[0024] The present invention also prepares chromium ion solidified microspheres by adsorbing ferrous sulfate and magnesium trifluoromethanesulfonate on activated carbon and coating nano-silicon dioxide on the surface thereof. When cement is ground, the activated carbon in the microspheres will adsorb hexavalent chromium in cement. At this time, the hexavalent chromium is reduced to trivalent chromium as much as possible under the synergistic reduction effect of ferrous sulfate and magnesium trifluoromethanesulfonate in the activated carbon, thereby improving the reduction efficiency of hexavalent chromium. The nano-silicon dioxide coated on the surface of the activated carbon will prevent the contact of ferrous sulfate with air, avoid the oxidation of ferrous sulfate, and avoid the contact of ferrous sulfate with grinding equipment, thereby reducing corrosion to the equipment. In addition, calcium hydroxide will be produced during the use of cement, and trivalent chromium will react with hydroxide to generate chromium hydroxide precipitation, which will be adsorbed on the surface of the activated carbon. Since the nano-silicon dioxide on the surface of the microspheres is highly active, the nano-silicon dioxide will react with calcium hydroxide to generate CSH gel during the cement process, further solidifying the chromium element in the CSH gel, thereby reducing the precipitation of the chromium element in the cement. In addition, magnesium ions in magnesium trifluoromethanesulfonate can participate in the hydration reaction of cement, promote the formation of hydration products, and improve the early strength and durability of cement; the sulfonate in magnesium trifluoromethanesulfonate has surface activity and can be adsorbed on the surface of cement particles, improving the dispersion of particles and reducing agglomeration, thereby improving the grinding efficiency of cement. By improving the fluidity and dispersion of cement particles, magnesium trifluoromethanesulfonate can reduce energy consumption in the grinding process and improve production efficiency.

[0025] Beneficial Effects

[0026] The grinding aid of the present invention innovatively adds chromium ion-cured microspheres, which not only has excellent hexavalent chromium reduction stability, but also can effectively cure the chromium element, and successfully solves the problem of equipment corrosion. In addition, by introducing special functional components modified cellulose ether, the shrinkage cracking of cement is reduced and the crack resistance of cement is improved. The grinding aid of the present invention achieves the curing of chromium ions and the significant improvement of the mechanical properties of cement by adding chromium ion-cured microspheres and modified cellulose ether. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto.

[0028] Example 1

[0029] A cement anti-cracking grinding aid for chromium ion solidification comprises the following raw materials in parts by weight: 3 parts of chromium ion solidification microspheres, 9 parts of modified cellulose ether, 20 parts of sorbitol, 3 parts of diethanol monoisopropanolamine, 15 parts of aluminum sulfate, 50 parts of deionized water, 10 parts of polymerized polyols, and 2 parts of sodium sulfate.

[0030] The preparation method of the modified cellulose ether is:

[0031] (1) Dispersing cellulose ether in anhydrous ethanol, ultrasonically treating for 30 minutes, adding cardanol and stirring evenly, then adding catalyst triethylamine and reacting at 60° C. for 6 hours. After the reaction is completed, washing with ethanol three times to remove unreacted cardanol and catalyst, and vacuum drying to obtain hydrophobically modified cellulose ether;

[0032] (2) Dissolve cocamidopropyl betaine in deionized water, add hydrophobically modified cellulose ether to prepare a 5% suspension, and ultrasonically treat for 30 minutes to ensure sufficient dispersion. Add polyethylene glycol diglycidyl ether and stir evenly, react at 50° C. for 4 hours, wash with deionized water three times after the reaction, and freeze-dry to obtain modified cellulose ether.

[0033] In the step (1), the molar ratio of cellulose ether to cardanol is 1:1.2; the amount of triethylamine added is 1% of the mass of cardanol; and the total mass ratio of anhydrous ethanol to cellulose ether and cardanol is 5:1.

[0034] In the step (2), the amount of polyethylene glycol diglycidyl ether added is 5% of the weight of the hydrophobically modified cellulose ether; and the amount of cocamidopropyl betaine added is 0.5% of the weight of the deionized water.

[0035] The chromium ion-cured microspheres include the following raw materials in parts by weight:

[0036] 5 parts of activated carbon, 8 parts of ferrous sulfate, 0.01 parts of magnesium trifluoromethanesulfonate, 40 parts of deionized water, 100 parts of anhydrous ethanol, 8 parts of ethyl orthosilicate, 0.01 parts of surfactant, and 2 parts of catalyst.

[0037] The preparation method of the chromium ion-cured microspheres is as follows:

[0038] S1: Grind the activated carbon, select the activated carbon with a particle size less than 1 μm and dry it in an oven at 105°C;

[0039] S2: adding ferrous sulfate and magnesium trifluoromethanesulfonate to deionized water, stirring evenly to obtain ferrous sulfate solution A, adding the activated carbon dried in step S1 to the ferrous sulfate solution A, ultrasonically dispersing for 10 minutes, and filtering to obtain activated carbon B adsorbing ferrous sulfate and magnesium trifluoromethanesulfonate;

[0040] S3: Add activated carbon B and surfactant to anhydrous ethanol and stir for 3 minutes, then continue to add pH adjuster and ammonia water, ultrasonically treat for 5 minutes, then drop 15 parts of tetraethyl orthosilicate at a speed of 400 r / min to react for 5 hours, and after the reaction is completed, filter to obtain chromium ion-cured microspheres.

[0041] In the preparation method of the chromium ion-cured microspheres, in step S3, a pH regulator is added until the pH of the solution is 8-10; the regulator is a sodium hydroxide solution.

[0042] A method for preparing a cement anti-cracking grinding aid for chromium ion solidification comprises the following steps:

[0043] Aluminum sulfate is added into deionized water and stirred until completely dissolved; sorbitol and polymerized polyol are added into the aluminum sulfate solution and stirred evenly; modified cellulose ether is slowly added and stirred continuously until completely dissolved to form a uniform solution; chromium ion-cured microspheres and diethanol monoisopropanolamine are added and stirred evenly; finally, sodium sulfate is added and stirred until completely dissolved; after stirring evenly, a cement anti-cracking grinding aid is obtained.

[0044] Example 2

[0045] A cement anti-cracking grinding aid for chromium ion solidification comprises the following raw materials in parts by weight: 5 parts of chromium ion solidification microspheres, 13 parts of modified cellulose ether, 27 parts of sorbitol, 7 parts of diethanol monoisopropanolamine, 23 parts of aluminum sulfate, 60 parts of deionized water, 15 parts of polymerized polyols, and 5 parts of sodium sulfate.

[0046] The preparation method of the modified cellulose ether is:

[0047] (1) Dispersing cellulose ether in anhydrous ethanol, ultrasonically treating for 30 minutes, adding cardanol and stirring evenly, then adding catalyst triethylamine and reacting at 60° C. for 6 hours. After the reaction is completed, washing with ethanol three times to remove unreacted cardanol and catalyst, and vacuum drying to obtain hydrophobically modified cellulose ether;

[0048] (2) Dissolve cocamidopropyl betaine in deionized water, add hydrophobically modified cellulose ether to prepare a 5% suspension, and ultrasonically treat for 30 minutes to ensure sufficient dispersion. Add polyethylene glycol diglycidyl ether and stir evenly, react at 50° C. for 4 hours, wash with deionized water three times after the reaction, and freeze-dry to obtain modified cellulose ether.

[0049] In the step (1), the molar ratio of cellulose ether to cardanol is 1:1.2; the amount of triethylamine added is 1% of the mass of cardanol; and the total mass ratio of anhydrous ethanol to cellulose ether and cardanol is 5:1.

[0050] In the step (2), the amount of polyethylene glycol diglycidyl ether added is 5% of the weight of the hydrophobically modified cellulose ether; and the amount of cocamidopropyl betaine added is 0.5% of the weight of the deionized water.

[0051] The chromium ion-cured microspheres include the following raw materials in parts by weight:

[0052] 10 parts of activated carbon, 14 parts of ferrous sulfate, 0.02 parts of magnesium trifluoromethanesulfonate, 50 parts of deionized water, 100 parts of anhydrous ethanol, 15 parts of ethyl orthosilicate, 0.07 parts of a surfactant, and 4 parts of a catalyst.

[0053] The preparation method of the chromium ion-cured microspheres is as follows:

[0054] S1: Grind the activated carbon, select the activated carbon with a particle size less than 1 μm and dry it in an oven at 105°C;

[0055] S2: adding ferrous sulfate and magnesium trifluoromethanesulfonate to deionized water, stirring evenly to obtain ferrous sulfate solution A, adding the activated carbon dried in step S1 to the ferrous sulfate solution A, ultrasonically dispersing for 10 minutes, and filtering to obtain activated carbon B adsorbing ferrous sulfate and magnesium trifluoromethanesulfonate;

[0056] S3: Add activated carbon B and surfactant to anhydrous ethanol and stir for 3 minutes, then continue to add pH adjuster and ammonia water, ultrasonically treat for 5 minutes, then drop 15 parts of tetraethyl orthosilicate at a speed of 400 r / min to react for 5 hours, and after the reaction is completed, filter to obtain chromium ion-cured microspheres.

[0057] In the preparation method of the chromium ion-cured microspheres, in step S3, a pH regulator is added until the pH of the solution is 8-10; the regulator is a sodium hydroxide solution.

[0058] A method for preparing a cement anti-cracking grinding aid for chromium ion solidification comprises the following steps:

[0059] Aluminum sulfate is added into deionized water and stirred until completely dissolved; sorbitol and polymerized polyol are added into the aluminum sulfate solution and stirred evenly; modified cellulose ether is slowly added and stirred continuously until completely dissolved to form a uniform solution; chromium ion-cured microspheres and diethanol monoisopropanolamine are added and stirred evenly; finally, sodium sulfate is added and stirred until completely dissolved; after stirring evenly, a cement anti-cracking grinding aid is obtained.

[0060] Example 3

[0061] A cement anti-cracking grinding aid for chromium ion solidification comprises the following raw materials in parts by weight: 10 parts of chromium ion solidification microspheres, 18 parts of modified cellulose ether, 35 parts of sorbitol, 10 parts of diethanol monoisopropanolamine, 30 parts of aluminum sulfate, 70 parts of deionized water, 20 parts of polymerized polyols, and 8 parts of sodium sulfate.

[0062] The preparation method of the modified cellulose ether is:

[0063] (1) Dispersing cellulose ether in anhydrous ethanol, ultrasonically treating for 30 minutes, adding cardanol and stirring evenly, then adding catalyst triethylamine and reacting at 60° C. for 6 hours. After the reaction is completed, washing with ethanol three times to remove unreacted cardanol and catalyst, and vacuum drying to obtain hydrophobically modified cellulose ether;

[0064] (2) Dissolve cocamidopropyl betaine in deionized water, add hydrophobically modified cellulose ether to prepare a 5% suspension, and ultrasonically treat for 30 minutes to ensure sufficient dispersion. Add polyethylene glycol diglycidyl ether and stir evenly, react at 50° C. for 4 hours, wash with deionized water three times after the reaction, and freeze-dry to obtain modified cellulose ether.

[0065] In the step (1), the molar ratio of cellulose ether to cardanol is 1:1.2; the amount of triethylamine added is 1% of the mass of cardanol; and the total mass ratio of anhydrous ethanol to cellulose ether and cardanol is 5:1.

[0066] In the step (2), the amount of polyethylene glycol diglycidyl ether added is 5% of the weight of the hydrophobically modified cellulose ether; and the amount of cocamidopropyl betaine added is 0.5% of the weight of the deionized water.

[0067] The chromium ion-cured microspheres include the following raw materials in parts by weight:

[0068] 30 parts of activated carbon, 20 parts of ferrous sulfate, 0.03 parts of magnesium trifluoromethanesulfonate, 85 parts of deionized water, 100 parts of anhydrous ethanol, 25 parts of ethyl orthosilicate, 0.32 parts of a surfactant, and 13 parts of a catalyst.

[0069] The preparation method of the chromium ion-cured microspheres is as follows:

[0070] S1: Grind the activated carbon, select the activated carbon with a particle size less than 1 μm and dry it in an oven at 105°C;

[0071] S2: adding ferrous sulfate and magnesium trifluoromethanesulfonate to deionized water, stirring evenly to obtain ferrous sulfate solution A, adding the activated carbon dried in step S1 to the ferrous sulfate solution A, ultrasonically dispersing for 10 minutes, and filtering to obtain activated carbon B adsorbing ferrous sulfate and magnesium trifluoromethanesulfonate;

[0072] S3: Add activated carbon B and surfactant to anhydrous ethanol and stir for 3 minutes, then continue to add pH adjuster and ammonia water, ultrasonically treat for 5 minutes, then drop 15 parts of tetraethyl orthosilicate at a speed of 400 r / min to react for 5 hours, and after the reaction is completed, filter to obtain chromium ion-cured microspheres.

[0073] In the preparation method of the chromium ion-cured microspheres, in step S3, a pH regulator is added until the pH of the solution is 8-10; the regulator is a sodium hydroxide solution.

[0074] A method for preparing a cement anti-cracking grinding aid for chromium ion solidification comprises the following steps:

[0075] Aluminum sulfate is added into deionized water and stirred until completely dissolved; sorbitol and polymerized polyol are added into the aluminum sulfate solution and stirred evenly; modified cellulose ether is slowly added and stirred continuously until completely dissolved to form a uniform solution; chromium ion-cured microspheres and diethanol monoisopropanolamine are added and stirred evenly; finally, sodium sulfate is added and stirred until completely dissolved; after stirring evenly, a cement anti-cracking grinding aid is obtained.

[0076] Comparative Example 1

[0077] A cement anti-cracking grinding aid for chromium ion solidification comprises the following raw materials in parts by weight: 10 parts of chromium ion solidification microspheres, 18 parts of modified cellulose ether, 35 parts of sorbitol, 10 parts of diethanol monoisopropanolamine, 30 parts of aluminum sulfate, 70 parts of deionized water, 20 parts of polymerized polyols, and 8 parts of sodium sulfate.

[0078] The preparation method of the modified cellulose ether is:

[0079] Dissolve cocamidopropyl betaine in deionized water, add cellulose ether to prepare a 5% suspension, and perform ultrasonic treatment for 30 minutes to ensure sufficient dispersion. Add polyethylene glycol diglycidyl ether and stir evenly, react at 50°C for 4 hours, wash with deionized water three times after the reaction, and freeze-dry to obtain modified cellulose ether.

[0080] In the step, the amount of polyethylene glycol diglycidyl ether added is 5% of the weight of cellulose ether; the amount of cocamidopropyl betaine added is 0.5% of the weight of deionized water.

[0081] The chromium ion-cured microspheres include the following raw materials in parts by weight:

[0082] 30 parts of activated carbon, 20 parts of ferrous sulfate, 0.03 parts of magnesium trifluoromethanesulfonate, 85 parts of deionized water, 100 parts of anhydrous ethanol, 25 parts of ethyl orthosilicate, 0.32 parts of a surfactant, and 13 parts of a catalyst.

[0083] The preparation method of the chromium ion-cured microspheres is as follows:

[0084] S1: Grind the activated carbon, select the activated carbon with a particle size less than 1 μm and dry it in an oven at 105°C;

[0085] S2: adding ferrous sulfate and magnesium trifluoromethanesulfonate to deionized water, stirring evenly to obtain ferrous sulfate solution A, adding the activated carbon dried in step S1 to the ferrous sulfate solution A, ultrasonically dispersing for 10 minutes, and filtering to obtain activated carbon B adsorbing ferrous sulfate and magnesium trifluoromethanesulfonate;

[0086] S3: Add activated carbon B and surfactant to anhydrous ethanol and stir for 3 minutes, then continue to add pH adjuster and ammonia water, ultrasonically treat for 5 minutes, then drop 15 parts of tetraethyl orthosilicate at a speed of 400 r / min to react for 5 hours, and after the reaction is completed, filter to obtain chromium ion-cured microspheres.

[0087] In the preparation method of the chromium ion-cured microspheres, in step S3, a pH regulator is added until the pH of the solution is 8-10; the regulator is a sodium hydroxide solution.

[0088] A method for preparing a cement anti-cracking grinding aid for chromium ion solidification comprises the following steps:

[0089] Aluminum sulfate is added into deionized water and stirred until completely dissolved; sorbitol and polymerized polyol are added into the aluminum sulfate solution and stirred evenly; modified cellulose ether is slowly added and stirred continuously until completely dissolved to form a uniform solution; chromium ion-cured microspheres and diethanol monoisopropanolamine are added and stirred evenly; finally, sodium sulfate is added and stirred until completely dissolved; after stirring evenly, a cement anti-cracking grinding aid is obtained.

[0090] Compared with Example 3, this comparative example uses the same raw materials and steps as Example 3, except that the cellulose ether is not subjected to the first step of modification.

[0091] Comparative Example 2

[0092] A cement anti-cracking grinding aid for chromium ion solidification comprises the following raw materials in parts by weight: 10 parts of chromium ion solidification microspheres, 18 parts of cellulose ether, 35 parts of sorbitol, 10 parts of diethanol monoisopropanolamine, 30 parts of aluminum sulfate, 70 parts of deionized water, 20 parts of polymerized polyols, and 8 parts of sodium sulfate.

[0093] The chromium ion-cured microspheres include the following raw materials in parts by weight:

[0094] 30 parts of activated carbon, 20 parts of ferrous sulfate, 0.03 parts of magnesium trifluoromethanesulfonate, 85 parts of deionized water, 100 parts of anhydrous ethanol, 25 parts of ethyl orthosilicate, 0.32 parts of a surfactant, and 13 parts of a catalyst.

[0095] The preparation method of the chromium ion-cured microspheres is as follows:

[0096] S1: Grind the activated carbon, select the activated carbon with a particle size less than 1 μm and dry it in an oven at 105°C;

[0097] S2: adding ferrous sulfate and magnesium trifluoromethanesulfonate to deionized water, stirring evenly to obtain ferrous sulfate solution A, adding the activated carbon dried in step S1 to the ferrous sulfate solution A, ultrasonically dispersing for 10 minutes, and filtering to obtain activated carbon B adsorbing ferrous sulfate and magnesium trifluoromethanesulfonate;

[0098] S3: Add activated carbon B and surfactant to anhydrous ethanol and stir for 3 minutes, then continue to add pH adjuster and ammonia water, ultrasonically treat for 5 minutes, then drop 15 parts of tetraethyl orthosilicate at a speed of 400 r / min to react for 5 hours, and after the reaction is completed, filter to obtain chromium ion-cured microspheres.

[0099] In the preparation method of the chromium ion-cured microspheres, in step S3, a pH regulator is added until the pH of the solution is 8-10; the regulator is a sodium hydroxide solution.

[0100] A method for preparing a cement anti-cracking grinding aid for chromium ion solidification comprises the following steps:

[0101] Aluminum sulfate is added into deionized water and stirred until completely dissolved; sorbitol and polymerized polyol are added into the aluminum sulfate solution and stirred evenly; cellulose ether is slowly added and stirred continuously until completely dissolved to form a uniform solution; chromium ion-cured microspheres and diethanol monoisopropanolamine are added and stirred evenly; finally, sodium sulfate is added and stirred until completely dissolved; after stirring evenly, a cement anti-cracking grinding aid is obtained.

[0102] Compared with Example 3, this comparative example has the same raw materials and steps as Example 3 except that the cellulose ether is not modified.

[0103] Comparative Example 3

[0104] A cement anti-cracking grinding aid for chromium ion solidification comprises the following raw materials in parts by weight: 10 parts of chromium ion solidification microspheres, 18 parts of modified cellulose ether, 35 parts of sorbitol, 10 parts of diethanol monoisopropanolamine, 30 parts of aluminum sulfate, 70 parts of deionized water, 20 parts of polymerized polyols, and 8 parts of sodium sulfate.

[0105] The preparation method of the modified cellulose ether is:

[0106] (1) Dispersing cellulose ether in anhydrous ethanol, ultrasonically treating for 30 minutes, adding cardanol and stirring evenly, then adding catalyst triethylamine and reacting at 60° C. for 6 hours. After the reaction is completed, washing with ethanol three times to remove unreacted cardanol and catalyst, and vacuum drying to obtain hydrophobically modified cellulose ether;

[0107] (2) Dissolve cocamidopropyl betaine in deionized water, add hydrophobically modified cellulose ether to prepare a 5% suspension, and ultrasonically treat for 30 minutes to ensure sufficient dispersion. Add polyethylene glycol diglycidyl ether and stir evenly, react at 50° C. for 4 hours, wash with deionized water three times after the reaction, and freeze-dry to obtain modified cellulose ether.

[0108] In the step (1), the molar ratio of cellulose ether to cardanol is 1:1.2; the amount of triethylamine added is 1% of the mass of cardanol; and the total mass ratio of anhydrous ethanol to cellulose ether and cardanol is 5:1.

[0109] In the step (2), the amount of polyethylene glycol diglycidyl ether added is 5% of the weight of the hydrophobically modified cellulose ether; and the amount of cocamidopropyl betaine added is 0.5% of the weight of the deionized water.

[0110] The chromium ion-cured microspheres include the following raw materials in parts by weight:

[0111] 30 parts of activated carbon, 20 parts of ferrous sulfate, 85 parts of deionized water, 100 parts of anhydrous ethanol, 25 parts of ethyl orthosilicate, 0.32 parts of surfactant, and 13 parts of catalyst.

[0112] The preparation method of the chromium ion-cured microspheres is as follows:

[0113] S1: Grind the activated carbon, select the activated carbon with a particle size less than 1 μm and dry it in an oven at 105°C;

[0114] S2: adding ferrous sulfate into deionized water and stirring to obtain ferrous sulfate solution A, adding the activated carbon dried in step S1 into the ferrous sulfate solution A, ultrasonically dispersing for 10 minutes, and filtering to obtain activated carbon B adsorbing ferrous sulfate;

[0115] S3: Add activated carbon B and surfactant to anhydrous ethanol and stir for 3 minutes, then continue to add pH adjuster and ammonia water, ultrasonically treat for 5 minutes, then drop 15 parts of tetraethyl orthosilicate at a speed of 400 r / min to react for 5 hours, and after the reaction is completed, filter to obtain chromium ion-cured microspheres.

[0116] In the preparation method of the chromium ion-cured microspheres, in step S3, a pH regulator is added until the pH of the solution is 8-10; the regulator is a sodium hydroxide solution.

[0117] A method for preparing a cement anti-cracking grinding aid for chromium ion solidification comprises the following steps:

[0118] Aluminum sulfate is added into deionized water and stirred until completely dissolved; sorbitol and polymerized polyol are added into the aluminum sulfate solution and stirred evenly; modified cellulose ether is slowly added and stirred continuously until completely dissolved to form a uniform solution; chromium ion-cured microspheres and diethanol monoisopropanolamine are added and stirred evenly; finally, sodium sulfate is added and stirred until completely dissolved; after stirring evenly, a cement anti-cracking grinding aid is obtained.

[0119] Compared with Example 3, this comparative example has the same raw materials and steps as Example 3 except that magnesium trifluoromethanesulfonate is not added during the preparation of chromium ion-cured microspheres.

[0120] Performance Testing

[0121] The above-mentioned Examples 1-3, Comparative Examples 1-3 and commercially available grinding aids were mixed into cement at a mixing amount of 0.05%, and a blank control was set, i.e., no grinding aid was added. The grinding aids and cement materials of each treatment group were poured into a 500mm×500mm standard cement test ball mill, respectively, and ground for 30 minutes. The various properties of the ground cement were tested, and the statistical data are shown in Table 1 below.

[0122] Test operation:

[0123] 45μm sieve residue test: Test the 45μm sieve residue of cement in accordance with GB / T 1345-2005 "Cement fineness test method sieve analysis method";

[0124] Cement strength test: Test the compressive strength and flexural strength of cement in accordance with GB / T17671-2021 "Test method for strength of cement mortar (ISO method)";

[0125] Specific surface area test: Determined in accordance with GB / T 8074-2008 "Determination of specific surface area of ​​cement - Blaine method";

[0126] Crack resistance test: The crack resistance test is carried out in accordance with JCT951-2005 "Test method for crack resistance of cement mortar".

[0127] Table 1 Cement performance test

[0128]

[0129] It can be seen from the data in Table 1 that the cement grinding aid of the embodiment of the present invention effectively improves the refinement of cement particles, improves the fluidity of cement particles, promotes hydration reaction, improves the strength and crack resistance of cement, and significantly improves the performance of cement.

[0130] Chromium reduction test:

[0131] Chromium content test: Determined in accordance with GB 31893-2015 "Limits and determination methods of water-soluble chromium (VI) in cement";

[0132] Table 2 Determination of hexavalent chromium content in cement

[0133]

[0134] From the data in Table 2, it can be seen that the grinding aid of the embodiment of the present invention has a significant chromium reduction effect, the hexavalent chromium removal rate can reach more than 80%, and the chromium reduction effect is significant for 90 days. The above results show that the grinding aid of the present invention has a stronger penetration effect, the chromium ion-cured microspheres have a more significant protective effect on ferrous sulfate, and the effect is more durable.

[0135] It should be noted that the above embodiments are only partial embodiments of the preferred methods of implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A cement anti-cracking grinding aid for chromium ion solidification, characterized in that: The invention comprises the following raw materials in parts by weight: 3-10 parts of chromium ion-cured microspheres, 9-18 parts of modified cellulose ether, 20-35 parts of sorbitol, 3-10 parts of diethanol monoisopropanolamine, 15-30 parts of aluminum sulfate, 50-70 parts of deionized water, 10-20 parts of polymerized polyols and 2-8 parts of sodium sulfate.

2. The cement anti-cracking grinding aid for chromium ion solidification according to claim 1, characterized in that: The preparation method of the modified cellulose ether is: (1) Dispersing cellulose ether in anhydrous ethanol, ultrasonically treating for 30 minutes, adding cardanol and stirring evenly, then adding catalyst triethylamine and reacting at 60° C. for 6 hours. After the reaction is completed, washing with ethanol three times to remove unreacted cardanol and catalyst, and vacuum drying to obtain hydrophobically modified cellulose ether; (2) Dissolve cocamidopropyl betaine in deionized water, add hydrophobically modified cellulose ether to prepare a 5% suspension, and ultrasonically treat for 30 minutes to ensure sufficient dispersion. Add polyethylene glycol diglycidyl ether and stir evenly, react at 50° C. for 4 hours, wash with deionized water three times after the reaction, and freeze-dry to obtain modified cellulose ether.

3. The cement anti-cracking grinding aid for chromium ion solidification according to claim 2, characterized in that: In the step (1), the molar ratio of cellulose ether to cardanol is 1:1.2; the amount of triethylamine added is 1% of the mass of cardanol; and the total mass ratio of anhydrous ethanol to cellulose ether and cardanol is 5:

1.

4. The cement anti-cracking grinding aid for chromium ion solidification according to claim 2, characterized in that: In the step (2), the amount of polyethylene glycol diglycidyl ether added is 5% of the weight of the hydrophobically modified cellulose ether; and the amount of cocamidopropyl betaine added is 0.5% of the weight of the deionized water.

5. The cement anti-cracking grinding aid for chromium ion solidification according to claim 1, characterized in that: The chromium ion-cured microspheres include the following raw materials in parts by weight: 5-30 parts of activated carbon, 8-20 parts of ferrous sulfate, 0.01-0.03 parts of magnesium trifluoromethanesulfonate, 40-85 parts of deionized water, 100 parts of anhydrous ethanol, 8-25 parts of ethyl orthosilicate, 0.01-0.32 parts of surfactant, and 2-13 parts of catalyst.

6. The cement anti-cracking grinding aid for chromium ion solidification according to claim 5, characterized in that: The preparation method of the chromium ion-cured microspheres is as follows: S1: Grind the activated carbon, select the activated carbon with a particle size less than 1 μm and dry it in an oven at 105°C; S2: Add ferrous sulfate and magnesium trifluoromethanesulfonate to deionized water and stir to obtain ferrous sulfate solution A. The dried activated carbon in S1 was added to the ferrous sulfate solution A, and ultrasonically dispersed for 10 min, and then filtered to obtain the activated carbon B that adsorbed ferrous sulfate and magnesium trifluoromethanesulfonate; S3: Add activated carbon B and surfactant to anhydrous ethanol and stir for 3 minutes, then continue to add pH adjuster and ammonia water, ultrasonically treat for 5 minutes, then drop 15 parts of tetraethyl orthosilicate at a speed of 400 r / min to react for 5 hours, and after the reaction is completed, filter to obtain chromium ion-cured microspheres.

7. The cement anti-cracking grinding aid for chromium ion solidification according to claim 6, characterized in that: In the preparation method of the chromium ion-cured microspheres, in step S3, a pH regulator is added until the pH of the solution is 8-10; the pH regulator is a sodium hydroxide solution.

8. A method for preparing the cement anti-cracking grinding aid for chromium ion solidification according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: Aluminum sulfate is added into deionized water and stirred until completely dissolved; sorbitol and polymerized polyol are added into the aluminum sulfate solution and stirred evenly; modified cellulose ether is slowly added and stirred continuously until completely dissolved to form a uniform solution; chromium ion-cured microspheres and diethanol monoisopropanolamine are added and stirred evenly; finally, sodium sulfate is added and stirred until completely dissolved; after stirring evenly, a cement anti-cracking grinding aid is obtained.

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