A raw material grinding aid for cement vertical mill and its preparation method and application

Abstract

The present invention relates to the technical field of cement production admixtures, and more particularly to a raw meal grinding aid for cement vertical mills, its preparation method, and its application. This invention addresses the operating mechanism of cement raw meal vertical mills and utilizes a combination of a polymer and a surfactant, along with various inorganic combustion-supporting components. By optimizing the addition amounts of each raw material, the invention produces a highly effective, weakly acidic raw meal grinding aid.

Description

Technical Field

[0001] The present invention relates to the technical field of cement production admixtures, in particular to a raw material grinding aid for a cement vertical mill, and a preparation method and application thereof. Background Art

[0002] Cement is a bulk industrial raw material used in daily production. Its production process mainly includes "two grindings and one burning", namely raw material grinding, clinker burning, and clinker grinding. In order to improve the grinding efficiency of cement raw material grinding, the existing technology often uses raw materials related to cement clinker grinding aids as the main materials, including organic grinding aid components and inorganic reinforcing components. In addition, combustion-supporting components and desulfurization and denitrification related materials are introduced. While increasing the raw material output per hour, it can also have the effects of saving coal, desulfurization, and denitrification. However, the above-mentioned cement clinker grinding aids have a series of problems in the raw material grinding process, which mainly focus on the fact that the main function of the grinding aid is to increase the raw material output per hour, but the effect on energy saving and consumption reduction is not obvious, and there is little research on the mechanism of raw material vertical mill grinding and coal saving and consumption reduction. At the same time, the use of strong acid or strong alkaline substances in the use of raw materials is likely to cause equipment corrosion and affect the quality of the raw material. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a raw meal grinding aid for a cement vertical mill and a preparation method thereof, and applies the same. Compared with the prior art, the present invention targets the operating mechanism of the cement raw meal vertical mill, adopts a combination of polymer substances and surfactants, and combines them with a variety of inorganic combustion-supporting components. By adjusting the optimal addition amount of each raw material, a high-efficiency weakly acidic raw meal grinding aid product is prepared.

[0004] Specifically, the preparation method of the raw meal grinding aid for cement vertical mill of the present invention comprises the following steps:

[0005] 1) Add graphene oxide to water and disperse it by ultrasonic to form a uniform and stable suspension A.

[0006] 2) Add acrylamide and suspension A into a three-necked flask, heat and stir until completely dissolved.

[0007] 3) Add ammonium persulfate to the three-necked flask, gradually increase the temperature and keep it warm to obtain solution B.

[0008] 4) Add sodium tripolyphosphate, sodium borate, citric acid, polyquaternium salt, calcium chloride and sodium nitrate to solution B, stir and dissolve to obtain the product.

[0009] Preferably, the ultrasonic dispersion time in step 1) is 20-60 min.

[0010] Preferably, step 2) is heated to 25-40°C.

[0011] Preferably, in step 3), the temperature is gradually raised to 80-95° C. and the holding time is 1-5 hours.

[0012] Preferably, the polyquaternium salt in step 4) is polyquaternium salt M550.

[0013] The present invention utilizes acrylamide to modify graphene oxide. The acrylamide contains a carbon-carbon double bond and an amide group, has the chemical properties of a double bond, is easily polymerized under ultraviolet irradiation or at a melting point temperature, and is self-polymerized under the initiation of the ammonium persulfate of the present invention to generate polyacrylamide. At the same time, because the graphene oxide matrix and edges contain a large number of oxygen-containing functional groups such as hydroxyl groups, carboxyl groups, and epoxy groups, the graphene oxide can be organically combined with an acrylamide solution or a polymer through covalent bond grafting or non-covalent bond modification, thereby reducing the problems of graphene agglomeration and poor dispersibility. The two cooperate with each other to effectively improve the grinding and firing aid effects.

[0014] Preferably, the weight parts of the raw materials added are: 50-55 parts of water, 3-5 parts of acrylamide, 0.03-0.06 parts of ammonium persulfate, 3-5 parts of polyquaternium salt, 5-10 parts of calcium chloride, 3-5 parts of graphene oxide, 3-5 parts of sodium tripolyphosphate, 5-10 parts of sodium borate, 3-5 parts of sodium nitrate, and 5-10 parts of citric acid.

[0015] More preferably, the weight parts of each raw material added are: 50 parts of water, 5 parts of acrylamide, 0.05 parts of ammonium persulfate, 5 parts of polyquaternium salt, 10 parts of calcium chloride, 5 parts of graphene oxide, 5 parts of sodium tripolyphosphate, 10 parts of sodium borate, 5 parts of sodium nitrate, and 10 parts of citric acid.

[0016] The present invention also relates to a raw meal grinding aid for cement vertical mill, which is specifically prepared by the above preparation method.

[0017] The present invention also relates to the use of the raw material grinding aid for cement vertical mill in cement raw material grinding. Preferably, the grinding aid is added in an amount of 0.12-0.2% of the mass of the cement raw material.

[0018] The cement raw material grinding aid prepared by the present invention has synergistic effects among its components, greatly improving the vertical mill grinding effect and clinker burning effect. For the vertical mill grinding effect, the present invention adds polyquaternium salt and acrylamide polymerization solution to achieve a stable material layer and sufficient grinding. At a suitable low concentration, the acrylamide polymerization solution can be regarded as a network structure, and the mechanical entanglement and hydrogen bonds between the chains together form network nodes, which can have good wettability and drag reduction. The polyquaternium salt M550 has excellent antistatic and drag reduction effects. In addition, the added sodium tripolyphosphate has an excellent suspension and dispersion effect in the vertical mill high-temperature grinding. For the clinker burning effect, the present invention adds a raw material mineralizer sodium nitrate to improve the raw material mineralization. In order to improve the calcinability of the material, sodium tripolyphosphate is added, which not only has a significant grinding aid effect, but also can induce the formation of solid solution through the high-temperature melting effect in the solid-phase reaction process, thereby accelerating the burning of the clinker. At the same time, the acidification and penetration effect of citric acid reduces the surface activation energy of calcium carbonate, increases the decomposition rate of calcium carbonate, and reduces its decomposition temperature, thereby achieving the effect of saving energy. The combustion-supporting effect of calcium chloride and graphene oxide, as well as the high specific surface area graphene oxide that can be fully coated on the surface of calcium carbonate, improve the full decomposition and burning of calcium carbonate, and facilitate the complete decomposition of solid-phase calcium carbonate to form liquid-phase clinker burning. The trace addition of sodium borate is beneficial to increase the activity of the calcination process and produce an air-entraining and fluxing effect.

[0019] In summary, the present invention can target the grinding mechanism of the vertical mill, stabilize the material layer, and fully grind, thereby increasing the hourly output of raw material grinding, and can also increase the raw material decomposition rate, promote the burning of clinker, and accelerate the solid-phase reaction, thereby reducing the standard coal consumption of cement clinker, saving coal consumption in cement kilns, effectively controlling the production cost of cement raw material grinding aids, and promoting cement companies to reduce costs and improve efficiency. DETAILED DESCRIPTION

[0020] In order to characterize the technical effect of the present invention, a raw meal grinding aid was prepared and the grinding aid effect of the raw meal grinding aid, the burnability of the ground cement raw meal and the performance of the resulting clinker were tested in accordance with the provisions of the standard documents T / CCAS 021-2021, GB / T-26566-2011, GB / T1345 2005 and GB / T17671-1999. The cement raw meal composition is: 4150 parts limestone, 75 parts coal gangue, 700 parts sandstone, and 75 parts iron slag. The limestone chemical composition is CaO 56.74%, SiO 8.45%, Al 2 O 3 1.22%, MgO 0.11%, Fe 3 O 4 0.49%, and loss on ignition 32.99%. A raw meal grinding aid is mixed with the cement raw meal at a ratio of 0.15% by mass and ground in a vertical cement raw meal mill for 6 hours. The ground product is then transferred to a cement dry process kiln and calcined according to the procedures in Section 8 of GB / T-26566-2011, with a maximum constant temperature of 1350°C, to produce cement clinker. A blank test is performed during the test, i.e., no raw meal grinding aid is added.

[0021] Among the test performances, the clinker compressive strength indicates the ability of the hardened clinker obtained after sintering the raw material to withstand external damage; the raw material burnability refers to the ease with which the cement raw material is combined with the clinker minerals after being calcined at a certain temperature and for a certain period of time, expressed by the mass content of free lime; and the 80μm grinding aid effect indicates the percentage of the weight of the material above the 80μm sieve after grinding to the weight of all the grinding products.

[0022] Example 1

[0023] The preparation method of the raw material grinding aid comprises the following steps:

[0024] 1) Add 1 part of graphene oxide to 50 parts of water and ultrasonically disperse for 30 minutes to form a uniform and stable suspension A.

[0025] 2) Add 2 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0026] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0027] 4) Add 5 parts of sodium tripolyphosphate, 10 parts of sodium borate, 10 parts of citric acid, 5 parts of polyquaternium M550, 10 parts of calcium chloride, and 5 parts of sodium nitrate to solution B, stir and dissolve to obtain.

[0028] Example 2

[0029] The preparation method of the raw material grinding aid comprises the following steps:

[0030] 1) Add 5 parts of graphene oxide to 50 parts of water and ultrasonically disperse for 30 minutes to form a uniform and stable suspension A.

[0031] 2) Add 5 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0032] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0033] 4) Add 5 parts of sodium tripolyphosphate, 10 parts of sodium borate, 10 parts of citric acid, 5 parts of polyquaternium M550, 10 parts of calcium chloride, and 5 parts of sodium nitrate to solution B, stir and dissolve to obtain.

[0034] Example 3

[0035] The preparation method of the raw material grinding aid comprises the following steps:

[0036] 1) Add 1 part of graphene oxide to 50 parts of water and ultrasonically disperse for 30 minutes to form a uniform and stable suspension A.

[0037] 2) Add 2 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0038] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0039] 4) Add 2 parts of sodium tripolyphosphate, 4 parts of sodium borate, 4 parts of citric acid, 2 parts of polyquaternium M550, 3 parts of calcium chloride, and 1 part of sodium nitrate to solution B, stir and dissolve to obtain.

[0040] Example 4

[0041] The preparation method of the raw material grinding aid comprises the following steps:

[0042] 1) 8 parts of graphene oxide were added to 50 parts of water and ultrasonically dispersed for 30 minutes to form a uniform and stable suspension A.

[0043] 2) Add 8 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0044] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0045] 4) Add 8 parts of sodium tripolyphosphate, 12 parts of sodium borate, 12 parts of citric acid, 8 parts of polyquaternium M550, 15 parts of calcium chloride, and 7 parts of sodium nitrate to solution B, stir and dissolve to obtain.

[0046] Comparative Example 1

[0047] The preparation method of the raw material grinding aid comprises the following steps:

[0048] 1) Add 5 parts of graphene oxide to 50 parts of water and ultrasonically disperse for 30 minutes to form a uniform and stable suspension A.

[0049] 2) Add 5 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0050] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0051] 4) Add 10 parts of sodium borate, 10 parts of citric acid, 5 parts of polyquaternium M550, 10 parts of calcium chloride, and 5 parts of sodium nitrate to solution B, stir and dissolve to obtain the product.

[0052] Comparative Example 2

[0053] The preparation method of the raw material grinding aid comprises the following steps:

[0054] 1) Add 5 parts of graphene oxide to 50 parts of water and ultrasonically disperse for 30 minutes to form a uniform and stable suspension A.

[0055] 2) Add 5 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0056] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0057] 4) Add 5 parts of sodium tripolyphosphate, 10 parts of citric acid, 5 parts of polyquaternium M550, 10 parts of calcium chloride, and 5 parts of sodium nitrate to solution B, stir and dissolve to obtain.

[0058] Comparative Example 3

[0059] The preparation method of the raw material grinding aid comprises the following steps:

[0060] 1) Add 5 parts of graphene oxide to 50 parts of water and ultrasonically disperse for 30 minutes to form a uniform and stable suspension A.

[0061] 2) Add 5 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0062] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0063] 4) Add 5 parts of sodium tripolyphosphate, 10 parts of sodium borate, 5 parts of polyquaternium M550, 10 parts of calcium chloride, and 5 parts of sodium nitrate to solution B, stir and dissolve to obtain.

[0064] Comparative Example 4

[0065] The preparation method of the raw material grinding aid comprises the following steps:

[0066] 1) Add 5 parts of graphene oxide to 50 parts of water and ultrasonically disperse for 30 minutes to form a uniform and stable suspension A.

[0067] 2) Add 5 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0068] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0069] 4) Add 5 parts of sodium tripolyphosphate, 10 parts of sodium borate, 10 parts of citric acid, 10 parts of calcium chloride and 5 parts of sodium nitrate to solution B, stir and dissolve to obtain the product.

[0070] Comparative Example 5

[0071] The preparation method of the raw material grinding aid comprises the following steps:

[0072] 1) Add 5 parts of graphene oxide to 50 parts of water and ultrasonically disperse for 30 minutes to form a uniform and stable suspension A.

[0073] 2) Add 5 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0074] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0075] 4) Add 5 parts of sodium tripolyphosphate, 10 parts of sodium borate, 10 parts of citric acid, 5 parts of polyquaternium M550, and 5 parts of sodium nitrate to solution B, stir and dissolve to obtain.

[0076] Comparative Example 6

[0077] The preparation method of the raw material grinding aid comprises the following steps:

[0078] 1) Add 5 parts of graphene oxide to 50 parts of water and ultrasonically disperse for 30 minutes to form a uniform and stable suspension A.

[0079] 2) Add 5 parts of acrylamide and suspension A into a three-necked flask, heat to 30°C, and stir until completely dissolved.

[0080] 3) Add 0.05 parts of ammonium persulfate to a three-necked flask, gradually raise the temperature to 90°C and keep warm for 2 hours to obtain solution B.

[0081] 4) Add 5 parts of sodium tripolyphosphate, 10 parts of sodium borate, 10 parts of citric acid, 5 parts of polyquaternium M550, and 10 parts of calcium chloride to solution B, stir and dissolve to obtain.

[0082] After testing, the test results are shown in the following table:

[0083]

[0084] From the comparison between the blank, Example 1 and Example 2, it can be seen that when the amount of graphene oxide and acrylamide in 50 parts of water is less than 3 to 5 parts, the grinding and dispersion effect will be reduced, which indicates that too little graphene oxide and acrylamide have an impact on the grinding effect of the raw material.

[0085] From the comparison of Example 2 and Example 3, it can be seen that when the amount of graphene oxide and acrylamide in 50 parts of water is less than 3-5 parts and the combustion aid, mineralizer, and grinding curing agent are reduced, the effects of raw material decomposition rate, clinker burning, solid phase reaction, etc. will be weakened, which will have a negative impact on the standard coal consumption and clinker strength of cement clinker.

[0086] From the comparison of Example 2 and Example 4, it can be seen that when the amounts of graphene oxide and acrylamide are increased beyond the corresponding dosage, and the dosage of the combustion aid, mineralizer, and grinding curing agent is increased, the effects on the decomposition rate of the raw meal, the burning of the clinker, the solid-phase reaction, etc. are not enhanced, but instead an inhibitory effect is produced on the grinding and dispersion. Therefore, it is shown that the dispersion effect of graphene oxide and acrylamide is best at a dosage of 3 to 5 parts, which can be beneficial to the crushing and grinding process, can reduce the raw meal grinding fineness, and increase the yield.

[0087] From Example 2 and Comparative Examples 1-2, it can be seen that sodium tripolyphosphate and sodium borate can complex the calcium components in the raw material under high-temperature vertical mill, accelerate the high-temperature melting effect of the solid-phase reaction process, induce the formation of solid solution, accelerate the burning effect of clinker, and thus reduce the amount of coal used in the cement kiln.

[0088] It can be seen from the results of Example 2 and Comparative Examples 3 to 4 that, during vertical mill grinding, the grinding and solidification effects of citric acid and polyquaternium-550 can penetrate into the limestone, producing antistatic and drag-reducing effects, thereby exhibiting excellent suspension and dispersion effects.

[0089] From the results of Example 2 and Comparative Examples 5 to 6, it can be seen that since calcium chloride and sodium nitrate have mineralization and combustion-supporting effects, under the synergistic effect of graphene oxide, the full decomposition and burning of calcium carbonate are improved, which is conducive to the complete decomposition of calcium carbonate from the solid phase, thereby reducing the standard coal consumption of cement clinker and saving coal consumption in the cement kiln.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate from the essence of the corresponding technical solutions.

[0091] The scope of the technical solutions of each embodiment of the present invention.

Claims

1. A method for preparing a raw material grinding aid for a cement vertical mill, characterized in that: The steps include: 1) Add graphene oxide to water and disperse it by ultrasonic to form a uniform and stable suspension A. 2) Add acrylamide and suspension A to a three-necked flask and heat with stirring until completely dissolved at a temperature of 25-40°C. 3) Add ammonium persulfate to the three-necked flask, gradually raise the temperature to 80-95°C and keep warm for 1-5 hours to obtain solution B; 4) sodium tripolyphosphate, sodium borate, citric acid, polyquaternium salt, calcium chloride, sodium nitrate were added to solution B, stirred to dissolve, to obtain; The weight parts of the raw materials added are: 50-55 parts of water, 3-5 parts of acrylamide, 0.03-0.06 parts of ammonium persulfate, 3-5 parts of polyquaternium salt, 5-10 parts of calcium chloride, 3-5 parts of graphene oxide, 3-5 parts of sodium tripolyphosphate, 5-10 parts of sodium borate, 3-5 parts of sodium nitrate, and 5-10 parts of citric acid.

2. The method for preparing the raw meal grinding aid for cement vertical mill according to claim 1, characterized in that: Step 1) Ultrasonic dispersion time is 20-60 min.

3. The method for preparing the raw meal grinding aid for cement vertical mill according to claim 1, characterized in that: Step 4) The polyquaternium salt is polyquaternium salt M550.

4. The method for preparing the raw meal grinding aid for cement vertical mill according to claim 3, characterized in that: The weight parts of the raw materials added are: 50 parts of water, 5 parts of acrylamide, 0.05 parts of ammonium persulfate, 5 parts of polyquaternium salt, 10 parts of calcium chloride, 5 parts of graphene oxide, 5 parts of sodium tripolyphosphate, 10 parts of sodium borate, 5 parts of sodium nitrate, and 10 parts of citric acid.

5. Raw material grinding aid for cement vertical mill, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the raw meal grinding aid for cement vertical mill according to claim 5 in cement raw meal grinding.

7. The use according to claim 6, characterized in that The amount of grinding aid added is 0.12-0.2% of the mass of cement raw material.

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