Coal-saving type raw material grinding aid and preparation method thereof

Abstract

The invention provides a coal-saving type raw material grinding aid and a preparation method thereof. The coal-saving type raw material grinding aid is prepared from the following raw materials in parts by weight: 20 to 30 parts of macromolecular grinding aid synergist, 15 to 20 parts of anionic dispersant, 10 to 20 parts of alkali metal salt, 1 to 2 parts of wetting agent and 20 to 40 parts of water, according to the coal-saving type raw material grinding aid, the macromolecular grinding aid synergist and the anionic dispersant interact, so that the coal-saving type raw material grinding aid improves the raw material grinding efficiency, improves the raw material burnability, saves coal resources and improves the clinker quality, and the coal-saving type raw material grinding aid has important significance on sustainable development of the cement industry. Particularly, when the mixing amount of the coal-saving type raw material grinding aid is 0.10-0.15% of the mass of the raw material, the yield of a raw material mill can be improved by 3-10%, the compressive strength of cement in 3d and 28d is improved by more than 2MPa, the standard coal consumption per ton of clinker is reduced by more than 2kg / t, and the effect is remarkable.

Description

Technical Field

[0001] The invention relates to the technical field of raw meal grinding aids, and in particular to a coal-saving raw meal grinding aid and a preparation method thereof. Background Art

[0002] As an important building material, cement plays a vital role in infrastructure construction. However, the cement production process consumes a lot of energy, especially the consumption of coal, which not only increases the production cost, but also causes serious pollution to the environment. Cement production is a high-energy consumption process, in which coal is the main source of energy consumption. In the raw material preparation stage, the grinding process requires a lot of electricity; in the clinker calcination stage, a lot of coal is needed to provide a high temperature environment. In order to reduce energy consumption in cement production and improve energy efficiency, certain cement additives are needed to help improve efficiency.

[0003] Traditional raw meal grinding aids can improve the grindability of raw meal, increase grinding efficiency, and reduce grinding power consumption; reduce the surface energy of raw meal particles, reduce the friction between particles, and make raw meal easier to grind; although traditional raw meal grinding aids improve the grinding efficiency of raw meal to a certain extent, it is difficult to grind raw meal particles to a sufficiently fine degree, which affects the quality of cement products. If the raw meal of cement is not ground fine enough, the raw meal will not be sufficient in the subsequent combustion and reaction process, which will affect the formation speed and quality of clinker, and may lead to a high content of free calcium oxide in the clinker, affecting the stability of the clinker; in clinker production, multiple admixtures are often used at the same time, such as water reducers, retarders, etc. Traditional raw meal grinding aids may interact with these admixtures, affecting each other's performance, resulting in the performance of cement failing to meet the design requirements. Traditional raw meal grinding aids mainly focus on improving grinding efficiency, but pay less attention to coal consumption in the clinker calcination process, and have a more limited effect on reducing coal consumption. Traditional raw meal grinding aids have a single composition and limited functions, and are difficult to meet the comprehensive requirements for energy conservation and consumption reduction in cement production. The effectiveness of traditional raw meal grinding aids is affected by factors such as raw meal properties, grinding equipment and process conditions, and has poor stability.

[0004] With the intensification of the energy crisis and the continuous improvement of environmental protection requirements, the cement industry has an increasingly urgent need for energy conservation and consumption reduction. Against this background, coal-saving raw meal grinding aids have emerged. Coal-saving raw meal grinding aids not only have the function of improving grinding efficiency like traditional raw meal grinding aids, but can also reduce coal consumption during the raw meal calcination process, achieve energy conservation and consumption reduction in clinker production, and improve clinker quality.

[0005] In view of the problems existing in the prior art, the present application aims to solve the problems that the raw meal grinding aid has average raw meal grinding efficiency, the raw meal after grinding has poor burnability, the amount of coal consumed in the raw meal burning process is high, and the quality of the clinker is average. Summary of the invention

[0006] Purpose of the invention:

[0007] The purpose of the present invention is to provide a coal-saving raw meal grinding aid, which can improve the raw meal grinding efficiency, improve the burnability of the raw meal, reduce coal consumption and improve the quality of clinker.

[0008] The technical solution of the present invention:

[0009] A coal-saving raw meal grinding aid, characterized in that the raw materials of the coal-saving raw meal grinding aid include, by weight, 20 to 30 parts of macromolecular grinding aid synergist, 15 to 20 parts of anionic dispersant, 10 to 20 parts of alkali metal salt, 1 to 2 parts of wetting agent, and 20 to 40 parts of water.

[0010] The preparation method of the macromolecular grinding aid synergist comprises the following steps:

[0011] S1: Add 2-methylmorpholineethyl methacrylate, acrylic acid, poly(ethylene glycol) hydroxypropyl methacrylate, and water into a reaction bottle, and stir evenly to obtain a reaction solution A;

[0012] S2: Add sodium persulfate, mercaptopropionic acid and water into another reaction bottle and stir evenly to obtain reaction solution B;

[0013] S3: heating the reaction solution A to 50-70°C, and then slowly adding the reaction solution B dropwise;

[0014] S4: After the dropwise addition is completed, the temperature is raised to 75-85° C. and the reaction is kept at this temperature for 2-4 hours to obtain a macromolecular grinding aid and synergist.

[0015] Furthermore, the weight average molecular weight of the poly(ethylene glycol) hydroxypropyl methacrylate is 18 to 25 kDa.

[0016] Furthermore, the mass ratio of 2-morpholineethyl methacrylate, acrylic acid, and poly(ethylene glycol) hydroxypropyl methacrylate is 1-2.5:1:10-15.

[0017] Furthermore, the mass of the sodium persulfate is 1.5% to 2.2% of the total mass of 2-morpholine ethyl methacrylate, acrylic acid, and poly(ethylene glycol) hydroxypropyl methacrylate; the mass of the mercaptopropionic acid is 0.1% to 0.2% of the total mass of 2-morpholine ethyl methacrylate, acrylic acid, and poly(ethylene glycol) hydroxypropyl methacrylate.

[0018] Furthermore, the amount of water in step S1 is 1.5 to 2.5 times the total mass of 2-morpholineethyl methacrylate, acrylic acid, and poly(ethylene glycol) hydroxypropyl methacrylate; the amount of water in step S2 is 10 to 15 times the total mass of sodium persulfate and mercaptopropionic acid.

[0019] Furthermore, the anionic dispersant is a mixture of one or more of sodium carboxymethyl cellulose, calcium lignin sulfonate, and sodium hexametaphosphate.

[0020] Furthermore, the alkali metal salt is a mixture of one or more of sodium acetate, potassium carbonate and sodium carbonate.

[0021] Furthermore, the wetting agent is a mixture of one or more of triethylene glycol, diethylene glycol and glycerol.

[0022] The present application also provides a method for preparing a coal-saving raw meal grinding aid, which is characterized in that it comprises the following steps: placing an anionic dispersant, an alkali metal salt, and water into a reactor, heating the temperature to 45-60°C, stirring at a speed of 400-500 rpm for 20-30 minutes, cooling the resulting solution to room temperature, and then adding a macromolecular grinding aid and a wetting agent into the reactor, stirring for 30-60 minutes, to obtain a coal-saving raw meal grinding aid.

[0023] Macromolecular grinding aids and enhancers contain polar groups that can be adsorbed on the surface of cement particles, reduce the friction and adhesion between particles, make the grinding process smoother, and improve the grinding efficiency. Macromolecular grinding aids and enhancers affect the mineral composition and microstructure of raw materials. Carboxyl groups can provide hydrogen ions in the raw material system, change the charge properties of the surface of raw material particles, reduce the electrostatic attraction between particles, and promote the dispersion of particles. The dispersed raw material particles have a larger specific surface area, which is conducive to the diffusion and reaction of ions, improves the reactivity of raw materials, and reduces the firing temperature. In addition, carboxyl groups can also react with metal ions in raw materials to form a relatively stable complex. This complex is easier to decompose and participate in the reaction at a lower temperature, promotes the transformation of minerals and thus promotes the decomposition of calcium carbonate, releases carbon dioxide at a lower temperature, and accelerates the formation of minerals such as dicalcium silicate and tricalcium silicate, thereby reducing coal consumption; grinding aids and dispersants improve the bulk density and pore structure of raw material particles, improve the thermal conductivity efficiency of raw materials, make heat more evenly distributed in raw materials, reduce heat waste, and thus reduce the use of coal. The carbon-carbon double bonds contained in the macromolecular grinding aid and synergist can be polarized at high temperatures, giving the polymer molecules a certain electron cloud mobility. This helps to adsorb and activate ions in the raw material, such as calcium ions and silicon ions, promote their diffusion and migration at lower temperatures, accelerate the solid-phase reaction between minerals in the raw material, and thus reduce the sintering temperature.

[0024] Anionic dispersants can be adsorbed on the surface of particles, disperse the particles through electrostatic repulsion, reduce agglomeration, and thus improve grinding efficiency. The combined effect of the two can make the particle size distribution of cement particles more reasonable, reduce the proportion of over-grinding and coarse particles, and improve the pertinence and efficiency of grinding. Anionic dispersants can reduce the viscosity of cement paste, make raw materials easier to flow during grinding and construction, and improve production efficiency and construction quality. Alkali metal salts can participate in the formation process of clinker minerals and change the composition and structure of minerals. Appropriate alkali metal salt content can promote the formation of beneficial minerals and improve the quality and performance of clinker. Good wetting properties can make clinker easier to mix with other materials during construction and improve the strength of cement.

[0025] In summary, the macromolecular grinding aids, anionic dispersants, alkali metal salts and wetting agents in the coal-saving raw meal grinding aids work synergistically through their respective mechanisms of action to improve the raw meal grinding efficiency, improve the burnability of the raw meal, save coal resources, and also improve the quality of the clinker.

[0026] Beneficial effects:

[0027] The macromolecular grinding aid and the anionic dispersant in the coal-saving raw meal grinding aid of the present invention interact with each other, so that the coal-saving raw meal grinding aid improves the raw meal grinding efficiency, improves the burnability of the raw meal after grinding, reduces the amount of coal consumed in the raw meal burning process, and improves the quality of the clinker, which is of great significance to the sustainable development of the cement industry. DETAILED DESCRIPTION

[0028] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0029] Unless otherwise specified, the chemical reagents used in the present invention are all commercially available analytically pure.

[0030] 2-Methyl methacrylate was purchased from Shanghai Bofei Meike Chemical Technology Co., Ltd.; poly(ethylene glycol) hydroxypropyl methacrylate was purchased from Shanghai Yuanye Biotechnology Co., Ltd., providing weight average molecular weights of 15kDa, 18kDa, 25kDa, and 30kDa; raw material grinding aid was purchased from Nanjing Changjiang Jiangyu Energy Technology Co., Ltd., with a glycerol content of 90%.

[0031] Preparation of macromolecular grinding aid and synergist A:

[0032] S1: 15 g of 2-morpholineethyl methacrylate, 10 g of acrylic acid, 100 g of poly(ethylene glycol) hydroxypropyl methacrylate (18 kDa), and 250 g of water were added to a reaction bottle and stirred to obtain a reaction solution A;

[0033] S2: Add 1.9 g of sodium persulfate, 0.2 g of mercaptopropionic acid, and 21 g of water to another reaction bottle and stir evenly to obtain reaction solution B;

[0034] S3: Raise the temperature of reaction solution A to 60°C, and then slowly dropwise add reaction solution B;

[0035] S4: After the dropwise addition is completed, the temperature is raised to 80°C and kept for reaction for 4 hours to obtain a macromolecular grinding aid and synergist.

[0036] Preparation of macromolecular grinding aid and synergist B:

[0037] The difference between this preparation and the macromolecular grinding aid and synergist A is that 15 g of 2-morpholine ethyl methacrylate, 10 g of acrylic acid, 100 g of poly(ethylene glycol) hydroxypropyl methacrylate (18 kDa), and 250 g of water in step S1 are replaced with 7.5 g of 2-morpholine ethyl methacrylate, 7.5 g of acrylic acid, 110 g of poly(ethylene glycol) hydroxypropyl methacrylate (25 kDa), and 250 g of water.

[0038] Preparation of macromolecular grinding aid and synergist C:

[0039] The difference between this preparation and the macromolecular grinding aid and synergist A is that 15 g of 2-methylmorpholine ethyl methacrylate, 10 g of acrylic acid, 100 g of poly(ethylene glycol) hydroxypropyl methacrylate (18 kDa), and 250 g of water in step S1 are replaced by 5 g of 2-methylmorpholine ethyl methacrylate, 10 g of acrylic acid, 110 g of poly(ethylene glycol) hydroxypropyl methacrylate (18 kDa), and 250 g of water.

[0040] Preparation of macromolecular grinding aid and synergist D:

[0041] The difference between the present preparation and the macromolecular grinding aid and synergist A is that the poly(ethylene glycol) hydroxypropyl methacrylate (18 kDa) in step S1 is replaced by poly(ethylene glycol) hydroxypropyl methacrylate (15 kDa).

[0042] Preparation of macromolecular grinding aid and synergist E:

[0043] The difference between the present preparation and the macromolecular grinding aid and synergist A is that the poly(ethylene glycol) hydroxypropyl methacrylate (18 kDa) in step S1 is replaced by poly(ethylene glycol) hydroxypropyl methacrylate (30 kDa).

[0044] Preparation of coal-saving raw meal grinding aids:

[0045] Anionic dispersant, alkali metal salt and water are placed in a reactor, heated to 60°C, stirred at 400 rpm for 20 minutes, the resulting solution is cooled to room temperature, and then macromolecular grinding aid and wetting agent are added to the reactor, stirred for 45 minutes to obtain a coal-saving raw meal grinding aid.

[0046] Examples 1 to 6

[0047] The coal-saving raw meal grinding aid was prepared according to the above-mentioned preparation method. Table 1 is the ingredient list of the coal-saving raw meal grinding aid of Examples 1 to 6, calculated by weight.

[0048] Table 1 Ingredients of coal-saving raw meal grinding aids of Examples 1 to 6

[0049]

[0050] Comparative Example 1

[0051] The difference between this preparation example and Example 2 is that the anionic dispersant is replaced with a commercially available dispersant ethanolamine salt.

[0052] Comparative Example 2

[0053] A commercially available raw material grinding aid was used, purchased from Nanjing Changjiang Jiangyu Energy Technology Co., Ltd., with a glycerol content of 90%.

[0054] Referring to the provisions in the standard documents T / CCAS 022-2021, GB / T 26566-2011, GB / T 1345-2005 and GB / T17671-2021, the grinding aid effect of the coal-saving raw meal grinding aid obtained in Examples 1 to 6 and Comparative Examples 1 to 2, the burnability of the raw meal after grinding and the performance of the obtained clinker were tested, and the amount of coal consumed in producing one ton of clinker was recorded.

[0055] 1. Fineness test: Add the coal-saving raw meal grinding aids of Examples 1 to 6 and Comparative Examples 1 to 2 to the raw meal, grind for 6 hours, control the fineness of the cement raw meal (80 μm sieve residue 13±2%), and count the raw meal production.

[0056] 2. Free calcium oxide content test: According to GB / T 176-2017 "Cement Chemical Analysis Methods", the coal-saving raw meal grinding aids of Examples 1 to 6 and Comparative Examples 1 to 2 were added to the raw meal, ground for 6 hours, and the free calcium oxide content of the ground cement raw meal was tested.

[0057] 3. Standard coal consumption per ton of clinker: The coal-saving raw meal grinding aids obtained in Examples 1 to 6 and Comparative Examples 1 to 2 are mixed with raw meal, the addition amount of the coal-saving raw meal grinding aid is 0.15% of the mass of the raw meal, the raw meal is put into a vertical mill, and vertically ground for 6 hours, and then the ground product is transferred to a cement dry kiln for calcination. The calcination reference standard GB / T 26566-2011 is used to control the maximum constant temperature to 1350°C to obtain the corresponding clinker. In production, coal is continuously put into the cement rotary kiln, and the amount of coal consumed in the production of unit clinker before and after the addition of the grinding aid after 72 hours is recorded, that is, the standard coal consumption per ton of clinker.

[0058] 4. Compressive strength test: According to the standard GB / T 17671-2021, the 3d / 28d compressive strength of the clinker prepared above was tested to obtain the 3d / 28d compressive strength of the clinker.

[0059] Performance test results Table 2:

[0060]

[0061] As can be seen from Table 3, the coal-saving raw meal grinding aid of the present invention can improve the grinding efficiency of cement, improve the burnability of raw meal, save coal resources, and improve the quality of clinker;

[0062] Specifically, from the comparison between Example 4 and Example 2, it can be seen that when preparing the macromolecular grinding aid and synergist, the unreasonable mass ratio of 2-methylmorpholineethyl methacrylate, acrylic acid, and poly(ethylene glycol) hydroxypropyl methacrylate will lead to the poor performance of the coal-saving raw meal grinding aid on the grinding efficiency of the raw meal, the calcinability of the raw meal, and the improvement of the compressive strength of the clinker, and the coal-saving efficiency will be reduced, and the expected effect will not be achieved, which is mainly manifested in the raw meal output per unit being reduced from 351t / h to 327t / h, the 28d compressive strength being reduced from 61.4MPa to 58.4MPa, and the standard coal consumption per ton of clinker being increased from 98.2kg / t to 100.6kg / t.

[0063] From the comparison between Examples 5 to 6 and Example 2, it can be seen that when preparing macromolecular grinding aids and synergists, unreasonable weight-average molecular weight of poly(ethylene glycol) hydroxypropyl methacrylate will lead to poor performance of coal-saving raw meal grinding aids on raw meal grinding efficiency, raw meal flammability, and improving clinker compressive strength, and the coal-saving efficiency will be reduced, and the expected effect will not be achieved; the main manifestations are that the raw meal output per unit is reduced from 351t / h to 321t / h and 324t / h, the 28d compressive strength is reduced from 61.4MPa to 58.6MPa and 58.4MPa, and the standard coal consumption per ton of clinker is increased from 98.2kg / t to 100.2kg / t and 100.8kg / t.

[0064] By comparing Comparative Example 1 with Example 2, it can be seen that without using anionic dispersants, the use of ethanolamine salt, a dispersant available on the market, will lead to poor performance of the coal-saving raw meal grinding aid on raw meal grinding efficiency, raw meal flammability, and improving the compressive strength of clinker, and the coal-saving efficiency will be reduced, and the expected effect will not be achieved; the main manifestations are that the raw meal output per ton is reduced from 351t / h to 328t / h, the 28d compressive strength is reduced from 61.4MPa to 56.9MPa, and the standard coal consumption per ton of clinker is increased from 98.2kg / t to 101.2kg / t.

[0065] From Comparative Example 2 and Example 2, it can be seen that the use of commercial raw meal grinding aids without using the prepared macromolecular grinding aids will lead to poor performance of the coal-saving raw meal grinding aids on raw meal grinding efficiency, raw meal burnability, and clinker compressive strength, and the coal-saving efficiency will be reduced, and the expected effect cannot be achieved. The main manifestations are that the raw meal output per unit is reduced from 351t / h to 329t / h, the 28d compressive strength is reduced from 61.4MPa to 57.5MPa, and the standard coal consumption per ton of clinker is increased from 98.2kg / t to 100.5kg / t.

[0066] The present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. The present invention provides a coal-saving raw meal grinding aid, characterized in that: The raw materials of the coal-saving raw meal grinding aid include, by weight, 20 to 30 parts of macromolecular grinding aid and synergist, 15 to 20 parts of anionic dispersant, 10 to 20 parts of alkali metal salt, 1 to 2 parts of wetting agent, and 20 to 40 parts of water.

2. The coal-saving raw meal grinding aid according to claim 1, characterized in that: The preparation method of the macromolecular grinding aid synergist comprises the following steps: S1: Add 2-methylmorpholineethyl methacrylate, acrylic acid, poly(ethylene glycol) hydroxypropyl methacrylate, and water into a reaction bottle and stir evenly to obtain a reaction solution A; S2: Add sodium persulfate, mercaptopropionic acid and water into another reaction bottle and stir evenly to obtain reaction solution B; S3: heating the reaction solution A to 50-70°C, and then slowly adding the reaction solution B dropwise; S4: After the dropwise addition is completed, the temperature is raised to 75-85° C. and the reaction is kept at this temperature for 2-4 hours to obtain a macromolecular grinding aid and synergist.

3. The coal-saving raw meal grinding aid according to claim 2, characterized in that: The weight average molecular weight of the poly(ethylene glycol) hydroxypropyl methacrylate is 18 to 25 kDa.

4. The coal-saving raw meal grinding aid according to claim 2, characterized in that: The mass ratio of 2-morpholineethyl methacrylate, acrylic acid and poly(ethylene glycol) hydroxypropyl methacrylate is 1-2.5:1:10-15.

5. The coal-saving raw meal grinding aid according to claim 2, characterized in that: The mass of the sodium persulfate is 1.5% to 2.2% of the total mass of 2-morpholine ethyl methacrylate, acrylic acid, and poly(ethylene glycol) hydroxypropyl methacrylate; the mass of the mercaptopropionic acid is 0.1% to 0.2% of the total mass of 2-morpholine ethyl methacrylate, acrylic acid, and poly(ethylene glycol) hydroxypropyl methacrylate.

6. The coal-saving raw meal grinding aid according to claim 2, characterized in that: The amount of water in step S1 is 1.5 to 2.5 times the total mass of 2-methylmorpholineethyl methacrylate, acrylic acid, and poly(ethylene glycol) hydroxypropyl methacrylate; the amount of water in step S2 is 10 to 15 times the total mass of sodium persulfate and mercaptopropionic acid.

7. The coal-saving raw meal grinding aid according to claim 1, characterized in that: The anionic dispersant is a mixture of one or more of sodium carboxymethyl cellulose, calcium lignin sulfonate, and sodium hexametaphosphate.

8. The coal-saving raw meal grinding aid according to claim 1, characterized in that: The alkali metal salt is a mixture of one or more of sodium acetate, potassium carbonate and sodium carbonate.

9. The coal-saving raw meal grinding aid according to claim 1, characterized in that: The wetting agent is a mixture of one or more of triethylene glycol, diethylene glycol and glycerol.

10. The method for preparing the coal-saving raw meal grinding aid according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: putting anionic dispersant, alkali metal salt and water into a reaction kettle, heating to 45-60°C, stirring at a speed of 400-500rpm for 20-30min, cooling the obtained solution to room temperature, adding macromolecular grinding aid and wetting agent into the reaction kettle, stirring for 30-60min, and obtaining a coal-saving raw meal grinding aid.

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