Additive for reducing cement flow velocity and preparation method thereof

Abstract

The invention discloses an admixture capable of reducing cement flow velocity, and belongs to the technical field of cement grinding admixtures. The additive comprises a diethanolisopropanolamine component, a sodium thiocyanate component, molasses, a carboxylic acid polymer and water. A carboxylic acid polymer formed by acrylic acid modified unsaturated polyol is introduced and is adsorbed on the surfaces of cement particles through a carboxyl structure, and the sliding resistance among the cement particles is increased by utilizing a long-chain branch structure, so that the cement fluidity is reduced. Secondly, sodium thiocyanate is added, so that the fluidity of the cement is further reduced, the setting time of the cement is shortened, the concrete is rapidly hardened, and the strength of the cement is improved. Therefore, the admixture provided by the invention can reduce the cement flow rate, improve the belt delivery capacity and meet the cement delivery requirements under the condition that the use effect of the grinding aid is not influenced.

Description

Technical Field

[0001] The invention belongs to the technical field of cement grinding admixtures, and particularly relates to an admixture for reducing cement flow velocity and a preparation method thereof. Background Art

[0002] Cement grinding aid is a chemical additive that improves the grinding effect and performance of cement. At present, cement grinding aids are usually made of alcohol amines, polyols, and inorganic salts as raw materials in different proportions. The focus is on improving cement grinding, increasing production, and improving cement quality. The use of cement grinding aids has brought a series of sustainable development advantages to cement production companies, such as energy saving and consumption reduction, increased hourly production, improved utilization of industrial waste residues, and reduced environmental pollution. It has great economic and social benefits and good development prospects.

[0003] Cement plants generally use pneumatic chutes and belt conveyors in the process of cement shipment or transfer. Pneumatic chute conveyors are generally devices for conveying from high to low positions. Generally, the better the cement fluidity, the faster the conveying speed. Belt conveyors are generally equipment for conveying from low to high positions. The conveying capacity of the belt is related to the belt's elevation angle. The fluidity of cement directly affects its performance in pneumatic chute and belt conveyor systems. High fluidity is conducive to pneumatic chute conveying, but may cause problems in belt conveying. We need to find a balance between these two needs. Cement shipments from cement plants along the Yangtze River in my country mainly rely on shipping. The belt elevation angle will change with the rise of the Yangtze River water level, resulting in a decrease in cement shipment capacity during the flood season. In addition, after the transformation of cement mills in some existing factories, the original belt shipment capacity is limited. In particular, after the use of conventional grinding aids, it is easy for cement to flow back too fast, affecting the belt shipment platform.

[0004] Therefore, it is particularly important to introduce raw materials to adjust the cement flow rate, reduce the cement flow rate, improve the belt transportation capacity, and meet the cement transportation requirements without affecting the effect of the grinding aid. Summary of the invention

[0005] The invention aims at the backflow problem caused by excessive cement flow caused by conventional grinding aids in cement conveyor belt transportation, and reduces the fluidity of cement by introducing appropriate amounts of carboxylic acid polymers and early strength inorganic salts, while ensuring that the admixture has good grinding aid and strengthening effects.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: An admixture for reducing cement flow rate is prepared from the following raw materials in parts by weight: 15-25 parts of diethanol monoisopropanolamine component, 15-25 parts of sodium thiocyanate component, 10-20 parts of molasses, 0.5-1 part of carboxylic acid polymer, and 30-60 parts of water.

[0007] Furthermore, the preparation method of the carboxylic acid polymer is: (1) Weigh 300-360 parts of unsaturated polyether polyol, add it into a container, then add 70 parts of water, and raise the temperature to 55-70°C to fully dissolve the unsaturated polyether polyol; (2) Weigh 30-35 parts of acrylic acid and 15-20 parts of water to prepare Liquid A, which is set aside; weigh 1-2 parts of bleaching powder and 0.5-1 part of mercaptoethanol and 15-20 parts of water to prepare Liquid B, which is set aside; (3) After the temperature of the polyether polyol solution in step (1) is constant at 30°C, 3-3.5 parts of hydrogen peroxide with a mass concentration of 27.5% are added, and after stirring for 10 minutes, liquid A and liquid B are added dropwise. Liquid A is added dropwise for 180 minutes, and liquid B is added dropwise for 210 minutes. After the addition is completed, the temperature is raised to 45°C and kept warm for 120 minutes; (4) After the heat preservation is completed, sodium hydroxide solution is added to adjust the pH value to 7-8 to obtain a carboxylic acid polymer.

[0008] Furthermore, the molecular weight of the unsaturated polyether polyol in step (1) is 5000-8000.

[0009] Furthermore, the unsaturated polyether polyol is one or more of diethylene glycol monovinyl ether, methyl allyl polyoxyethylene ether and isopentanol polyoxyethylene ether.

[0010] Furthermore, the diethanol monoisopropanolamine component adopts a commercially available product, wherein the content of diethanol monoisopropanolamine is 85%.

[0011] Furthermore, the sodium thiocyanate component adopts a commercially available product, which is an industrial-grade raw material with a sodium thiocyanate content of 99%.

[0012] Furthermore, the molasses is a by-product of sugarcane sugar production and has a solid content of more than 75%.

[0013] A method for preparing an admixture for reducing cement flow rate comprises the following steps: (1) Pour water into a stirring tank, add sodium thiocyanate component and stir to dissolve; (2) Add the diethanol monoisopropanolamine component and molasses into the mixing tank and stir quickly and evenly; (3) Preparation of carboxylic acid polymers; (4) The carboxylic acid polymer is finally added into the mixing tank and rapidly stirred for 1 hour to obtain an admixture for reducing cement flow rate.

[0014] An admixture for reducing cement flow rate, the dosage of which is 0.05-0.12wt% of the cement weight.

[0015] All raw materials of the present invention are commercially available.

[0016] The carboxylic acid polymer obtained by the acrylic acid modified polyether polyol introduced by the present invention has a larger molecular weight and more branched structures. Suitable high molecular weight and long branched structures can enhance the steric hindrance effect between the polyether polyol and cement particles, more effectively hindering the movement of cement particles to reduce its flow rate. At the same time, the molecular weight of the unsaturated polyether polyol is not easy to be too large, and the excessive molecular weight level will affect the polymerization activity, affect the chain growth of the molecules of the carboxylic acid polymer, and finally affect the product performance. In addition, the acrylic acid group also chemically reacts with the cement hydration product, changes the morphology and crystallization habit of the hydration product, thereby reducing the rheological properties of the cement paste.

[0017] Secondly, sodium thiocyanate is added as an orthorhombic crystal or powder with strong hygroscopic properties. Its high hygroscopicity will quickly combine with the moisture in the cement, further reducing the fluidity of the cement.

[0018] Secondly, sodium thiocyanate can react quickly with tricalcium aluminate (C3A) in cement to generate hydration products. These hydration products form a dense protective film on the surface of cement particles, which promotes the hydration process of cement, promotes the role of carboxylic acid polymers, and also accelerates the development of early strength. In addition, an appropriate amount of sodium thiocyanate can shorten the setting time of cement and make concrete harden quickly. Therefore, the addition of sodium thiocyanate can not only reduce the cement flow rate, but also significantly improve the early strength of concrete. High early strength is conducive to shortening the construction period and improving construction efficiency.

[0019] Beneficial Effects (1) The present invention uses high molecular weight polyether to synthesize carboxylic acid polymers, which are adsorbed on the surface of cement particles through the carboxyl structure, and the long branched chain structure is used to increase the sliding resistance between cement particles, thereby reducing the fluidity of cement.

[0020] (2) The present invention uses sodium thiocyanate to further reduce the fluidity of cement by taking advantage of its easy moisture absorption and hardening. At the same time, it can shorten the setting time of cement, make the concrete harden quickly and improve the strength of cement.

[0021] (3) The present invention synthesizes a high molecular weight long chain carboxylic acid polymer and adds an early strength inorganic salt. The two work together to effectively reduce the cement flow rate, thereby solving the backflow problem caused by excessive cement fluidity caused by conventional grinding aids during cement conveyor belt transportation, while ensuring that the admixture has good grinding aid and strengthening effects. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto.

[0023] Example 1 An admixture for reducing cement flow rate is prepared from the following raw materials in parts by weight: 15 parts of diethanol monoisopropanolamine component, 15 parts of sodium thiocyanate component, 10 parts of molasses, 0.5 parts of carboxylic acid polymer, and 30 parts of water.

[0024] The preparation method of the carboxylic acid polymer is: (1) Weigh 300 parts of an unsaturated polyether polyol with a molecular weight of 5000 and add it to a four-necked flask, then add 70 parts of water and raise the temperature to 55°C to fully dissolve the unsaturated polyether polyol; (2) Weigh 30 parts of acrylic acid and 15 parts of water to prepare Liquid A, which is set aside; weigh 1 part of bleaching powder and 0.5 parts of mercaptoethanol and 15 parts of water to prepare Liquid B, which is set aside; (3) After the temperature of the polyether solution in step (1) is constant at 30°C, 3 parts of hydrogen peroxide with a mass concentration of 27.5% are added, and after stirring for 10 minutes, liquid A and liquid B are added dropwise. Liquid A is added dropwise for 180 minutes, and liquid B is added dropwise for 210 minutes. After the addition is completed, the temperature is raised to 45°C and kept warm for 120 minutes; (4) After the heat preservation is completed, sodium hydroxide solution is added to adjust the pH value to 7-8 to obtain a carboxylic acid polymer.

[0025] The diethanol monoisopropanolamine component is a commercially available product, wherein the content of diethanol monoisopropanolamine is 85%.

[0026] The unsaturated polyether polyol is methyl allyl polyoxyethylene ether The sodium thiocyanate component is a commercially available product, and is an industrial-grade raw material with a sodium thiocyanate content of 99%.

[0027] The molasses is a by-product of sugarcane sugar production, and has a solid content of more than 75%.

[0028] A method for preparing an admixture for reducing cement flow rate comprises the following steps: (1) Pour water into a stirring tank, add sodium thiocyanate component and stir to dissolve; (2) Add the diethanol monoisopropanolamine component and molasses into the mixing tank and stir quickly and evenly; (3) Preparation of carboxylic acid polymers; (3) The carboxylic acid polymer is finally added into the mixing tank and rapidly stirred for 1 hour to obtain an admixture for reducing cement flow rate.

[0029] An admixture for reducing cement flow rate, the dosage of which is 0.05-0.12wt% of the cement weight.

[0030] Example 2 An admixture for reducing cement flow rate is prepared from the following raw materials in parts by weight: 20 parts of diethanol monoisopropanolamine component, 20 parts of sodium thiocyanate component, 15 parts of molasses, 1 part of carboxylic acid polymer, and 45 parts of water.

[0031] The preparation method of the carboxylic acid polymer is: (1) Weigh 330 parts of an unsaturated polyether polyol with a molecular weight of 7000 and add it to a four-necked flask, then add 70 parts of water and raise the temperature to 65°C to fully dissolve the unsaturated polyether polyol; (2) Weigh 32 parts of acrylic acid and 18 parts of water to prepare Liquid A, which is set aside; weigh 2 parts of bleaching powder and 1 part of mercaptoethanol and 18 parts of water to prepare Liquid B, which is set aside; (3) After the temperature of the polyether solution in step (1) is constant at 30°C, 3 parts of hydrogen peroxide with a mass concentration of 27.5% are added, and after stirring for 10 minutes, liquid A and liquid B are added dropwise. Liquid A is added dropwise for 180 minutes, and liquid B is added dropwise for 210 minutes. After the addition is completed, the temperature is raised to 45°C and kept warm for 120 minutes; (4) After the heat preservation is completed, sodium hydroxide solution is added to adjust the pH value to 7-8 to obtain a carboxylic acid polymer.

[0032] The diethanol monoisopropanolamine component is a commercially available product, wherein the content of diethanol monoisopropanolamine is 85%.

[0033] The unsaturated polyether polyol is diethylene glycol monovinyl ether.

[0034] The sodium thiocyanate component is a commercially available product, and is an industrial-grade raw material with a sodium thiocyanate content of 99%.

[0035] The molasses is a by-product of sugarcane sugar production, and its solid content is more than 75%.

[0036] A method for preparing an admixture for reducing cement flow rate comprises the following steps: (1) Pour water into a stirring tank, add sodium thiocyanate component and stir to dissolve; (2) Add the diethanol monoisopropanolamine component and molasses into the mixing tank and stir quickly and evenly; (3) Preparation of carboxylic acid polymers; (4) The carboxylic acid polymer is finally added into the mixing tank and rapidly stirred for 1 hour to obtain an admixture for reducing cement flow rate.

[0037] An admixture for reducing cement flow rate, the dosage of which is 0.05-0.12wt% of the cement weight.

[0038] Example 3 An admixture for reducing cement flow rate is prepared from the following raw materials in parts by weight: 25 parts of diethanol monoisopropanolamine component, 25 parts of sodium thiocyanate component, 20 parts of molasses, 1 part of carboxylic acid polymer, and 60 parts of water.

[0039] The preparation method of the carboxylic acid polymer is: (1) Weigh 360 parts of an unsaturated polyether polyol with a molecular weight of 8000 and add it to a four-necked flask, then add 70 parts of water and raise the temperature to 70°C to fully dissolve the unsaturated polyether polyol; (2) Weigh 35 parts of acrylic acid and 20 parts of water to prepare Liquid A, which is set aside; weigh 1 part of bleaching powder and 0.5 parts of mercaptoethanol and 20 parts of water to prepare Liquid B, which is set aside; (3) After the temperature of the polyether solution in step (1) is constant at 30°C, 3.5 parts of hydrogen peroxide with a mass concentration of 27.5% are added, and after stirring for 10 minutes, liquid A and liquid B are added dropwise, with liquid A added for 180 minutes and liquid B added for 210 minutes. After the addition is completed, the temperature is raised to 45°C and kept warm for 120 minutes; (4) After the heat preservation is completed, sodium hydroxide solution is added to adjust the pH value to 7-8 to obtain a carboxylic acid polymer.

[0040] The diethanol monoisopropanolamine component is a commercially available product, wherein the diethanol monoisopropanolamine content is 85%. The unsaturated polyether polyol is prenol polyoxyethylene ether.

[0041] The sodium thiocyanate component is a commercially available product, and is an industrial-grade raw material with a sodium thiocyanate content of 99%.

[0042] The molasses is a by-product of sugarcane sugar production, and its solid content is more than 75%.

[0043] A method for preparing an admixture for reducing cement flow rate comprises the following steps: (1) Pour water into a stirring tank, add sodium thiocyanate component and stir to dissolve; (2) Add the diethanol monoisopropanolamine component and molasses into the mixing tank and stir quickly and evenly; (3) Preparation of carboxylic acid polymers; (3) The carboxylic acid polymer is finally added into the mixing tank and rapidly stirred for 1 hour to obtain an admixture for reducing cement flow rate.

[0044] An admixture for reducing cement flow rate, the dosage of which is 0.05-0.12wt% of the cement weight.

[0045] Comparative Example 1 An admixture for reducing cement flow rate is prepared from the following raw materials in parts by weight: 20 parts of diethanol monoisopropanolamine component, 20 parts of sodium chloride, 15 parts of molasses, 1 part of carboxylic acid polymer, and 45 parts of water.

[0046] The preparation method of the carboxylic acid polymer is: (1) Weigh 330 parts of an unsaturated polyether polyol with a molecular weight of 7000 and add it to a four-necked flask, then add 70 parts of water and raise the temperature to 65°C to fully dissolve the unsaturated polyether polyol; (2) Weigh 32 parts of acrylic acid and 18 parts of water to prepare Liquid A, which is set aside; weigh 2 parts of bleaching powder and 1 part of mercaptoethanol and 18 parts of water to prepare Liquid B, which is set aside; (3) After the temperature of the polyether solution in step (1) is constant at 30°C, 3 parts of hydrogen peroxide with a mass concentration of 27.5% are added, and after stirring for 10 minutes, liquid A and liquid B are added dropwise, with liquid A added for 180 minutes and liquid B added for 210 minutes. After the addition is completed, the temperature is raised to 45°C and kept warm for 120 minutes; (4) After the heat preservation is completed, sodium hydroxide solution is added to adjust the pH value to 7-8 to obtain a carboxylic acid polymer.

[0047] The diethanol monoisopropanolamine component is a commercially available product, wherein the content of diethanol monoisopropanolamine is 85%.

[0048] The unsaturated polyether polyol is diethylene glycol monovinyl ether.

[0049] The molasses is a by-product of sugarcane sugar production, and its solid content is more than 75%.

[0050] A method for preparing an admixture for reducing cement flow rate comprises the following steps: (1) Pour water into a mixing tank, add sodium chloride and stir to dissolve; (2) Add diethanol monoisopropanolamine and molasses into the mixing tank and stir quickly and evenly; (3) The carboxylic acid polymer is finally added into the mixing tank and rapidly stirred for 1 hour to obtain an admixture for reducing cement flow rate.

[0051] An admixture for reducing cement flow rate, the dosage of which is 0.05-0.12wt% of the cement weight.

[0052] The only difference between this comparative example and Example 2 is that an equal amount of sodium chloride is used to replace sodium thiocyanate.

[0053] Comparative Example 2 An admixture for reducing cement flow rate is prepared from the following raw materials in parts by weight: 20 parts of diethanol monoisopropanolamine component, 20 parts of sodium thiocyanate component, 15 parts of molasses, 1 part of diethylene glycol, and 45 parts of water.

[0054] The diethanol monoisopropanolamine component is a commercially available product, wherein the content of diethanol monoisopropanolamine is 85%.

[0055] The unsaturated polyether polyol is diethylene glycol monovinyl ether.

[0056] The sodium thiocyanate component is a commercially available product, and is an industrial-grade raw material with a sodium thiocyanate content of 99%.

[0057] The molasses is a by-product of sugarcane sugar production, and its solid content is more than 75%.

[0058] A method for preparing an admixture for reducing cement flow rate comprises the following steps: (1) Pour water into a stirring tank, add sodium thiocyanate component and stir to dissolve; (2) Add the diethanol monoisopropanolamine component and molasses into the mixing tank and stir quickly and evenly; (3) Finally, add diethylene glycol into the mixing tank and stir rapidly for 1 hour to obtain an admixture for reducing cement flow rate.

[0059] An admixture for reducing cement flow rate, the dosage of which is 0.05-0.12wt% of the cement weight.

[0060] The only difference between this comparative example and Example 2 is that an equal amount of diethylene glycol is used to replace the carboxylic acid polymer.

[0061] Comparative Example 3 An admixture for reducing cement flow rate is prepared from the following raw materials in parts by weight: 20 parts of diethanol monoisopropanolamine component, 20 parts of sodium chloride, 15 parts of molasses, 1 part of diethylene glycol, and 45 parts of water.

[0062] The only difference between this comparative example and Example 2 is that diethylene glycol is used instead of the carboxylic acid polymer and sodium chloride is used instead of sodium thiocyanate.

[0063] Comparative Example 4 An admixture for reducing cement flow rate is prepared from the following raw materials in parts by weight: 20 parts of diethanol monoisopropanolamine component, 20 parts of sodium thiocyanate component, 15 parts of molasses, 1 part of carboxylic acid polymer, and 45 parts of water.

[0064] The preparation method of the carboxylic acid polymer is as follows: (1) weighing 330 parts of an unsaturated polyether polyol with a molecular weight of 3000, adding the mixture into a four-necked flask, then adding 70 parts of water, and heating the mixture to 65° C. to fully dissolve the unsaturated polyether polyol; (2) weighing 32 parts of acrylic acid and 18 parts of water to prepare a liquid A for standby use; and weighing 2 parts of bleaching powder and 1 part of mercaptoethanol and 18 parts of water to prepare a liquid B for standby use; (3) after the temperature of the polyether solution in step (1) is constant at 30° C., adding 3 parts of 27.5% hydrogen peroxide, stirring for 10 minutes, and then dripping the liquid A and the liquid B, dripping the liquid A for 180 minutes, and dripping the liquid B for 210 minutes, and heating the mixture to 45° C. and keeping the temperature for 120 minutes after the dripping is completed; and (4) after the insulation is completed, adding a sodium hydroxide solution to adjust the pH value to 7-8, thereby obtaining a carboxylic acid polymer.

[0065] The only difference between this comparative example and Example 2 is that the molecular weight of the unsaturated polyether polyol used is 3000.

[0066] Comparative Example 5 Similar to Comparative Example 4, the only difference between this comparative example and Example 2 is that the molecular weight of the unsaturated polyether polyol used is 9,000.

[0067] Performance Testing Test operation: Divide into 9 test groups, weigh 5kg of cement in each test group, and prepare it according to the ratio of 90% clinker, 5% gravel, and 5% desulfurized gypsum. Then add the above examples 1-3, comparative examples 1-5 and commercially available grinding aids to the cement of the 4 experimental groups, and the amount of addition is 0.05% of the weight of cement. Then the cement of the 9 test groups is added to a Φ500×500mm cement ball mill for 30 minutes and then discharged from the mill. The admixtures for reducing cement flow rate prepared in the above examples and comparative examples, a commercially available cement grinding aid, and a blank without cement grinding aid are tested for various properties, and their various properties are statistically analyzed (data are shown in Table 1 below): Test Method (1) Determine the 45μm sieve residue and 80μm sieve residue of cement according to GB / T 1345-2005 “Test method for cement fineness”; (2) The determination of cement repose angle shall refer to the test method in GB / T 26748-2011 “Cement Grinding Aids”; (3) The cement setting time test is based on GB / T 1346-2011 "Test Methods for Water Consistency, Setting Time and Stability of Cement Standard Consistency"; (4) The compressive and flexural strength tests of cement mortar are based on GB / T 17671-2021 "Test method for strength of cement mortar".

[0068] Table 1. Results of various performance tests As can be seen from Table 1, the cement fineness, flexural strength and compressive strength of the admixtures of Examples 1-3 are consistent with or even better than those of the comparative examples and the addition of conventional commercial grinding aids. In addition, the setting time of the present invention is shorter than that of the commercial grinding aids, and the angle of repose of Examples 1-3 is significantly greater than that of the commercial grinding aids. The larger the angle of repose, the lower the fluidity. This shows that the joint use of sodium thiocyanate and carboxylic acid polymers of the present invention can increase the angle of repose of cement, reduce cement fluidity, and solve the backflow problem caused by excessive cement fluidity caused by grinding aids during cement belt transportation without affecting the effect of the use of grinding aids. In comparative examples 1-5 in which the key components are changed, the synergistic balance between the carboxylic acid polymer and the early strength inorganic salt sodium thiocyanate is weakened, thus resulting in a decline in various properties.

[0069] The relevant large-scale grinding experiment was carried out in the factory using Example 2 of the present invention. The shipping data when a conventional commercially available grinding aid product was used on September 20 was selected as a comparison. The industrial experiment using Example 2 was started on October 15. The specific data are shown in Table 2.

[0070] Table 2. Cement shipment data during industrial trials From the data in Table 2, it can be seen that since October 15, the shipment volume of PC425 cement has gradually increased from 240 tons to 390 tons, with a peak of about 480 tons. The shipment volume of PII52.5 cement has gradually increased from 260 tons to 410 tons, with a peak of about 530 tons. During this period, the conveyor belt shipment process was stable and no backflow occurred. This shows that industrial experiments verify that the relevant technology for reducing cement fluidity involved in the present invention can solve practical problems differently from conventional grinding aids.

[0071] 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. An admixture for reducing cement flow rate, It is characterized in that The invention comprises the following raw materials in parts by weight: 15-25 parts of diethanol monoisopropanolamine components, 15-25 parts of sodium thiocyanate components, 10-20 parts of molasses, 0.5-1 parts of carboxylic acid polymers and 30-60 parts of water.

2. The admixture for reducing cement flow rate according to claim 1, It is characterized in that The preparation method of the carboxylic acid polymer is: (1) Weigh 300-360 parts of unsaturated polyether polyol, add it into a container, then add 70 parts of water, and raise the temperature to 55-70°C to fully dissolve the unsaturated polyether polyol; (2) Weigh 30-35 parts of acrylic acid and 15-20 parts of water to prepare Liquid A, which is set aside; weigh 1-2 parts of bleaching powder and 0.5-1 part of mercaptoethanol and 15-20 parts of water to prepare Liquid B, which is set aside; (3) After the temperature of the polyether polyol solution in step (1) is constant at 30°C, 3-3.5 parts of hydrogen peroxide with a mass concentration of 27.5% are added, and after stirring for 10 minutes, liquid A and liquid B are added dropwise. Liquid A is added dropwise for 180 minutes, and liquid B is added dropwise for 210 minutes. After the addition is completed, the temperature is raised to 45°C and kept warm for 120 minutes; (4) After the heat preservation is completed, sodium hydroxide solution is added to adjust the pH value to 7-8 to obtain a carboxylic acid polymer.

3. The admixture for reducing cement flow rate according to claim 2, It is characterized in that The molecular weight of the unsaturated polyether polyol in step (1) is 5000-8000.

4. The admixture for reducing cement flow rate according to claim 1, It is characterized in that The content of diethanol monoisopropanolamine in the diethanol monoisopropanolamine component is 85%.

5. The admixture for reducing cement flow rate according to claim 1, It is characterized in that The sodium thiocyanate component is an industrial-grade raw material with a sodium thiocyanate content of 99%.

6. The admixture for reducing cement flow rate according to claim 1, It is characterized in that The molasses is a by-product of sugarcane sugar production, and has a solid content of more than 75%.

7. The admixture for reducing cement flow rate according to any one of claims 1 to 6, It is characterized in that The dosage of admixture is 0.05-0.12% of cement weight.

8. A method for preparing the admixture for reducing cement flow rate according to any one of claims 1 to 6, It is characterized in that The following steps are involved: (1) Pour water into a stirring tank, add sodium thiocyanate component and stir to dissolve; (2) Add the diethanol monoisopropanolamine component and molasses into the mixing tank and stir quickly and evenly; (3) Preparation of carboxylic acid polymers; (4) The carboxylic acid polymer is finally added into the mixing tank and stirred for 1 hour to obtain an admixture for reducing cement flow rate.

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