Preparation and application method of solid waste-based low-carbon cement clinker special mineralizer

Abstract

The application discloses a kind of solid waste-based low-carbon cement clinker special mineralizer preparation and application method, it is related to low-carbon cement clinker production technical field, including the following steps: S1: titanium gypsum is added to water, and add certain ammonia water, phosphorus gypsum and crystal form control agent;S2: the material in S1 is stirred and ultrasonic oscillation, while passing into cement kiln tail gas;S3: after a period of time, the liquid in S2 is filtered;The present application integrates a number of problems existing in cement plant, by utilizing cement kiln tail gas to modify titanium gypsum mineralization, obtain high-iron phase low-carbon cement clinker special mineralizer, and utilize the special mineralizer to produce low-carbon cement clinker, the main component of mineralized titanium gypsum is calcium carbonate, the sulfur content is very low, can be used in cement clinker production, is conducive to large-scale absorption of titanium gypsum solid waste, and the cement clinker produced is high-iron phase low-carbon clinker, such low-carbon cement has the characteristics of low carbon emission, strong erosion resistance, good fluidity.

Description

Technical Field

[0001] This invention relates to the field of low-carbon cement clinker production technology, specifically to a method for preparing and applying a special mineralizer for solid waste-based low-carbon cement clinker. Background Technology

[0002] Co-processing in cement production is an important way to dispose of bulk solid waste. Currently, the resource utilization rate of titanium gypsum is very low. Some high-grade titanium gypsum can be directly used as a cement retarder. However, due to excessive impurities and high water content in most titanium gypsum, it leads to a significant decrease in cement strength, thus making it unsuitable for direct use as a cement retarder. Existing technologies such as flotation and washing can improve the grade of titanium gypsum, but the maximum dosage when used as a cement retarder is only 5% of the cement, limiting its utilization capacity. Furthermore, the high sulfur content in titanium gypsum also prevents its large-scale use as a substitute raw material in clinker production.

[0003] The cement industry accounts for approximately 13% of China's total carbon emissions, second only to coal-fired power. Furthermore, 60% of the cement industry's carbon emissions come from carbon dioxide generated during the high-temperature calcination and decomposition of raw materials in the process. Reducing this portion of carbon emissions is challenging and requires adjustments to raw materials and processes. Ferrophase low-carbon cement is a new type of low-carbon silicate cement with advantages such as high erosion resistance, good fluidity, and wear resistance. Due to its low calcium content and low firing temperature, it can simultaneously reduce carbon emissions from raw materials and the firing process, while also lowering production costs. However, ferrophase cement has traditionally been used as a specialty cement. When used as general-purpose silicate cement, it suffers from insufficient strength, especially low early strength, which can affect construction progress. Therefore, a method for preparing and applying a special mineralizer for solid waste-based low-carbon cement clinker is needed to address these issues. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a special mineralizer for solid waste-based low-carbon cement clinker, so as to solve the problems existing in the prior art mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing a mineralizer specifically for solid waste-based low-carbon cement clinker includes the following steps:

[0007] S1: Add titanium gypsum to water, and add a certain amount of ammonia, phosphogypsum and crystal form control agent;

[0008] S2: Stir and ultrasonically vibrate the material in S1, and simultaneously introduce cement kiln exhaust gas;

[0009] S3: After the reaction continues for a period of time, the liquid in S2 is filtered.

[0010] S4: The filtered liquid is crystallized to obtain ammonium sulfate product, and the filtered solid is a mineralized product, which is a special mineralizer for low-carbon cement clinker.

[0011] Preferably, the titanium gypsum component comprises 1-5% TiO2, 5-10% Fe2O3, 30-50% CaO and 30-40% SO3 by weight.

[0012] Preferably, the mineralizer component for low-carbon cement clinker comprises 1-8% TiO2, 5-12% Fe2O3, 40-53% CaO and 0.5-10% SO3 by weight, with a loss on ignition of 30-44%.

[0013] Preferably, the specific surface area of ​​the low-carbon cement clinker mineralizer particles is 0.5-5 m². 2 / g.

[0014] Preferably, the crystal form control agent includes one or more of methanol, ethanol, glycerol, ethanolamine, polyethylene glycol, aspartic acid, glutamic acid, glycine, and sodium phosphate, and the liquid temperature in S2 is controlled at 15-30°C by a circulating cooling device.

[0015] A method for applying a special mineralizer for low-carbon cement clinker based on solid waste includes the following steps: after the special mineralizer for low-carbon cement clinker is dried by the waste heat of cement kiln tail gas, it is added to the raw meal in a certain proportion. After the special mineralizer for low-carbon cement clinker and the raw meal are ground and homogenized together, they are calcined at high temperature to obtain low-carbon cement clinker.

[0016] Preferably, the raw material is composed of limestone, clay, and aluminosilicate corrective material, and the dosage of the low-carbon cement clinker mineralizer is 2-35% by weight.

[0017] Preferably, the specific steps of the high-temperature calcination are as follows: raising the temperature from room temperature to 800-1000℃ and holding it for 10-90 minutes, then raising the temperature to 1200℃~1350℃ and holding it for 10-90 minutes.

[0018] Preferably, the low-carbon cement clinker composition comprises 50-64% CaO, 18-25% SiO2, 2-6% Al2O3, and 5-10% Fe2O3 by weight, wherein the content of C4AF mineral is 16-25%.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This invention integrates several existing problems in cement plants. By utilizing cement kiln tail gas to mineralize and modify titanium gypsum, a special mineralizer for high-iron phase low-carbon cement clinker is obtained. This special mineralizer is then used to produce low-carbon cement clinker. The main component of the mineralized titanium gypsum is calcium carbonate, with a very low sulfur content. It can be used in large quantities for cement clinker production, which is beneficial for the large-scale disposal of titanium gypsum solid waste. Moreover, the produced cement clinker is a high-iron phase low-carbon clinker. This type of low-carbon cement has the characteristics of low carbon emissions, strong erosion resistance, and good fluidity.

[0021] 2. In this invention, the titanium dioxide in the mineralized titanium gypsum can act as a mineralizing agent for iron-phase minerals, making it more suitable for high-iron-phase low-carbon cement. Titanium is mainly dissolved in the iron phase. By replacing iron ions, it can increase the aluminum-iron ratio of the iron phase, thereby increasing the activity of iron-phase minerals, improving the hydration rate, and helping to solve the problem of insufficient early strength in high-iron-phase low-carbon cement.

[0022] 3. In this invention, a small amount of titanium is dissolved in C2S, maintaining C2S in a highly active crystal structure (α-C2S). This can increase the C2S mineral content in high-iron phase low-carbon clinker without changing the cement strength, thereby further reducing carbon emissions. Trace amounts of copper, zinc and other impurities in the mineralized titanium gypsum can also be dissolved in the clinker minerals, enhancing their activity. In addition, the added phosphogypsum is acidic, which can not only adjust the pH, but also has a certain mineralizing effect.

[0023] 4. In this invention, the mineralized titanium gypsum particles are very small, and the calcium carbonate mainly exists in the metastable aragonite crystal form. It can rapidly decompose at a relatively low temperature during clinker calcination and produce calcium oxide microcrystals. The fine calcium oxide microcrystals help to generate a large number of fine C2S crystals in the solid-phase reaction and also help to nucleate C3S minerals in the subsequent liquid-phase reaction. Therefore, it can increase the C3S content in the clinker minerals, and control the crystal size of C3S by controlling the heat preservation time, which helps to solve the problem of insufficient early strength of high-iron phase low-carbon cement. Attached Figure Description

[0024] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0025] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0026] Please see Figure 1 The present invention provides the following technical solutions:

[0027] A method for preparing a mineralizer specifically for solid waste-based low-carbon cement clinker includes the following steps:

[0028] S1: Add titanium gypsum to water, and add a certain amount of ammonia, phosphogypsum and crystal form control agent;

[0029] S2: Stir and ultrasonically vibrate the material in S1, and simultaneously introduce cement kiln exhaust gas;

[0030] S3: After the reaction continues for a period of time, the liquid in S2 is filtered.

[0031] S4: The filtered liquid is crystallized to obtain ammonium sulfate product, and the filtered solid is a mineralized product, which is a special mineralizer for low-carbon cement clinker.

[0032] The crystal form control agent includes one or more of methanol, ethanol, glycerol, ethanolamine, aspartic acid, and glutamic acid. The pH value of the solution is adjusted by adding phosphogypsum. Phosphogypsum can also be mineralized with titanium gypsum by carbon dioxide. The calcium carbonate crystallization process is regulated by ultrasonic vibration to control the grain size and control the calcium carbonate crystal form to be mainly aragonite.

[0033] Prepare a special mineralizer (mineralized titanium gypsum) for low-carbon cement clinker using the method described above.

[0034] The chemical composition of the raw materials, titanium gypsum, mineralized titanium gypsum, etc. used in the examples and comparative examples is shown in the table below.

[0035]

[0036] Example 1

[0037] The low-carbon, high-ferrous phase clinker ratios were KH = 0.87, SM = 2.15, and IM = 0.7. The clinker was heated from room temperature to 900℃ and held for 30 minutes, then heated to 1325℃ and held for 30 minutes. After rapid cooling, the clinker was ground together with 5% dihydrate gypsum and 5% limestone to approximately 350 mg / L. 2 The / kg ratio is used to form P·II silicate cement, and the raw meal proportioning scheme is shown in Table 1:

[0038] Table 1 Raw Material Mixing Scheme 1

[0039] limestone sandstone fly ash Iron tailings Mineralized titanium gypsum 58.1％ 13.0％ 1.7％ 0％ 27.2％

[0040] Example 2

[0041] The only difference from Example 1 is the formulation, which reduces the amount of mineralized titanium gypsum. The formulation is shown in Table 2:

[0042] Table 2 Raw Material Mixing Scheme 2

[0043] limestone sandstone fly ash Iron tailings Mineralized titanium gypsum 64.3％ 12.7％ 1.7％ 1.4％ 20.0％

[0044] Example 3

[0045] The only difference from Example 1 is the ingredient formulation, which reduces the amount of mineralized titanium gypsum. The ingredient formulation is shown in Table 3:

[0046] Table 3 Raw Material Mixing Scheme 3

[0047] limestone sandstone fly ash Iron tailings Mineralized titanium gypsum 72.8％ 12.2％ 1.6％ 3.4％ 10.0％

[0048] Example 4

[0049] The only difference from Example 1 is the ingredient formulation, which reduces the amount of mineralized titanium gypsum. The ingredient formulation is shown in Table 4:

[0050] Table 4 Raw Material Mixing Scheme 4

[0051] limestone sandstone fly ash Iron tailings Mineralized titanium gypsum 78.8％ 11.8％ 1.6％ 4.8％ 3.0％

[0052] Comparative Example 1

[0053] The difference from Example 1 lies in the type of raw materials and the batching scheme. In Comparative Example 1, untreated titanium gypsum was used, and the batching was carried out according to the same rate value as in Example 1. However, due to the inconsistency in composition between titanium gypsum and mineralized titanium gypsum, the clinker composition will differ. Therefore, the SO3 content of the clinker calcined in Comparative Example 1 is approximately 1.9%, which exceeds the requirements of the recommended national standard. The raw material batching scheme is shown in Table 5:

[0054] Table 5 Raw Material Mixing Scheme 5

[0055] limestone sandstone fly ash Iron tailings Titanium plaster 78.8％ 11.7％ 1.6％ 4.9％ 3.0％

[0056] Comparative Example 2

[0057] The difference from Example 1 lies in the types of raw materials and the formulation. Comparative Example 2 did not add titanium gypsum or mineralized titanium gypsum, but only used traditional clinker raw materials to prepare high-iron phase low-carbon clinker. The raw material formulation is shown in Table 6:

[0058] Table 6 Raw Material Batching Scheme 6

[0059] limestone sandstone fly ash Iron tailings Mineralized titanium gypsum 81.3％ 11.7％ 1.6％ 5.4％ 0％

[0060] Comparative Example 3

[0061] Commercially available P·II silicate cement mainly consists of silicate cement clinker, dihydrate gypsum, and limestone.

[0062] The mortar strength of the P·II silicate cement used in each example and comparative example was tested according to the requirements of national standard GB / T 17671. The test results are shown in the table below:

[0063] Table 7. Test results of compressive strength of different P·II cements

[0064] 3-day compressive strength 28-day compressive strength Example 1 29.6 56.5 Example 2 31.8 57.8 Example 3 28.5 55.9 Example 4 25.0 50.2 Comparative Example 1 25.7 50.1 Comparative Example 2 24.2 48.7 Comparative Example 3 32.7 58.6

[0065] Take the P·II silicate cement from each example and comparative example, and test the free calcium oxide content according to the national standard GB / T 176. The lower the free calcium oxide content, the higher the degree of clinker firing reaction and the more complete the reaction.

[0066] Table 8. Test results of free calcium oxide in different P·II cements

[0067] Free calcium oxide content Example 1 0.45 Example 2 0.48 Example 3 0.55 Example 4 0.84 Comparative Example 1 0.82 Comparative Example 2 0.92 Comparative Example 3 1.01

[0068] According to Tables 7 and 8, and in conjunction with Comparative Examples 2 and 3, while high-ferrous phase low-carbon cement possesses advantages such as low carbon content, high erosion resistance, and good fluidity, it suffers from relatively low strength. Comparative Example 1 incorporated a small amount (3%) of untreated titanium gypsum. Due to the mineralizing effect of sulfur in the gypsum, the resulting cement exhibited slightly higher strength and lower free calcium oxide content than Comparative Example 2. However, the SO3 content in Comparative Example 1 exceeded the recommended national standard requirements, and it easily caused scaling and blockage in the clinker firing equipment.

[0069] In Example 4, a small amount (3%) of titanium gypsum mineralization product (mineralized titanium gypsum) was added. Due to the very low sulfur content in the product, although it could slightly improve cement strength, the effect was not as good as in Comparative Example 1. In Examples 3 and 2, the added titanium gypsum mineralization product was higher, reaching 10-20%. Since the titanium gypsum mineralization product also contained a small amount of residual sulfur (1-2% in this example, which can be controlled through the mineralization process), a better sulfur-to-titanium ratio resulted in a better strength improvement effect on clinker. Therefore, Examples 2 and 3 significantly improved cement strength and facilitated clinker sintering and reduced free calcium oxide content. The cement strength in Example 2 was already very close to that of the commercially available cement in Comparative Example 3. In Example 1, the theoretical maximum amount (27.2%) of titanium gypsum mineralization product under these conditions was added. At this point, the impurity content was too high, and titanium elements may have reacted with calcium ions to form low-activity perovskite, leading to a slight decrease in cement strength.

[0070] This invention utilizes cement kiln tail gas to mineralize and modify titanium gypsum, obtaining a special mineralizer for high-ferrous phase low-carbon cement clinker. After mineralization, the titanium gypsum is processed to produce two products: ammonium sulfate and mineralized titanium gypsum. The main component of mineralized titanium gypsum is calcium carbonate, with a very low sulfur content, allowing it to be used extensively in cement clinker production. This facilitates large-scale disposal of titanium gypsum solid waste, and the resulting clinker is a high-ferrous phase low-carbon clinker. This type of low-carbon cement is characterized by low carbon emissions, strong erosion resistance, and good fluidity.

[0071] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a mineralizer specifically for solid waste-based low-carbon cement clinker, characterized in that, Includes the following steps: S1: Add titanium gypsum to water, and add ammonia, phosphogypsum and crystal form control agent; S2: Stir and ultrasonically vibrate the material in S1, and simultaneously introduce cement kiln exhaust gas; S3: After the reaction continues for a period of time, the liquid in S2 is filtered. S4: The filtered liquid is crystallized to obtain ammonium sulfate product, and the filtered solid is a mineralized product, which is a special mineralizer for low-carbon cement clinker. The crystal form control agent includes one or more of methanol, ethanol, glycerol, ethanolamine, polyethylene glycol, aspartic acid, glutamic acid, glycine, and sodium phosphate. The liquid temperature in S2 is controlled at 15-30°C by a circulating cooling device.

2. The method for preparing a special mineralizer for solid waste-based low-carbon cement clinker according to claim 1, characterized in that, The titanium gypsum composition includes 1-5% TiO2, 5-10% Fe2O3, 30-50% CaO and 30-40% SO3 by weight.

3. The method for preparing a special mineralizer for solid waste-based low-carbon cement clinker according to claim 1, characterized in that, The mineralizer component for low-carbon cement clinker comprises 1-8% TiO2, 5-12% Fe2O3, 40-53% CaO and 0.5-10% SO3 by weight, with a loss on ignition of 30-44%.

4. The method for preparing a special mineralizer for solid waste-based low-carbon cement clinker according to claim 1, characterized in that, The prepared low-carbon cement clinker mineralizer has a particle specific surface area of ​​0.5-5 m². 2 / g.

5. A method for applying a special mineralizer for solid waste-based low-carbon cement clinker, comprising applying the special mineralizer for solid waste-based low-carbon cement clinker prepared by any one of the preparation methods described in claims 1-4, characterized in that, The specific steps are as follows: After the special mineralizer for low-carbon cement clinker is dried by the waste heat of cement kiln tail gas, it is added to the raw meal. After the special mineralizer for low-carbon cement clinker and the raw meal are ground and homogenized together, they are calcined at high temperature to obtain low-carbon cement clinker.

6. The application method of the special mineralizer for solid waste-based low-carbon cement clinker according to claim 5, characterized in that, The raw material is composed of limestone, clay, and aluminosilicate corrective materials, and the dosage of the low-carbon cement clinker mineralizer is 2-35% by weight.

7. The application method of the special mineralizer for solid waste-based low-carbon cement clinker according to claim 5, characterized in that, The specific steps of the high-temperature calcination are as follows: raise the temperature from room temperature to 800-1000℃ and hold for 10-90 minutes, then raise the temperature to 1200℃~1350℃ and hold for 10-90 minutes.

8. The application method of the special mineralizer for solid waste-based low-carbon cement clinker according to claim 5, characterized in that, The low-carbon cement clinker composition includes 50-64% CaO, 18-25% SiO2, 2-6% Al2O3, and 5-10% Fe2O3 by weight, wherein the content of C4AF mineral is 16-25%.

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