A melting accelerator and its preparation and application

Abstract

The application discloses a melting accelerator and preparation and application thereof. The melting accelerator comprises the following components in parts by weight: 10-25 parts of a grinding aid, 15-25 parts of a decomposition promoter, 10-20 parts of a mineralizer, and 30-65 parts of water; the grinding aid comprises at least two of polyether polyol, polyglycerol and sodium glucoheptonate; and the decomposition promoter comprises at least two of silver acetate, silver hexafluoroantimonate and sodium nitrate. The melting accelerator can be applied in a cement clinker sintering process. The application aims at the problem that the mineralizer added in the cement clinker calcination process cannot simultaneously control the cement clinker setting time and the raw material burnability and decomposition heat efficiency, and a liquid type melting accelerator with low dosage and stable and uniform efficacy is prepared through reasonable collocation of grinding components, decomposition components and mineralization components. The accelerator can stimulate the activity of the cement clinker, promote the decomposition of carbonates, improve the burnability of the raw material, and reduce the actual coal consumption in the clinker calcination process.

Description

Technical Field

[0001] This invention relates to a cement clinker calcination additive and its preparation method, and more particularly to a melting accelerator, its preparation, and its application in cement clinker calcination. Background Technology

[0002] During the calcination of cement clinker, calcium carbonate consumes a significant amount of heat through endothermic decomposition. Lowering the decomposition temperature (heat of decomposition) of calcium carbonate is crucial for reducing energy consumption in clinker calcination and for reducing the overall energy consumption of the cement industry.

[0003] Cement mineralizers generally refer to one or more composite substances added during the cement clinker production process. These substances can improve and promote the decomposition of carbonates, increase the decomposition heat efficiency, shorten the clinker mineral formation time, and improve the burnability of raw materials. The main types of mineralizers include: (1) sulfates, such as pyrite, natural gypsum, and phosphogypsum; (2) fluorides, such as fluorite, phosphorus slag, and barite tailings; and (3) phosphates, such as apatite and phosphorus industrial slag. Although these mineralizers can lower the sintering temperature, the amount of mineralizers used is limited to avoid introducing excessive P2O5, which would reduce the clinker strength and prolong the setting time. Generally, the P2O5 content introduced by the doping of phosphate mineralizers is controlled to not exceed 0.5%. The mineralizers with limited usage have a relatively limited effect on improving the burnability of raw materials and promoting the decomposition of carbonates. Therefore, developing an accelerator that can not only ensure that the strength of cement clinker does not change significantly, but also significantly improve the burnability of raw materials and the efficiency of decomposition heat has become an urgent technical problem to be solved.

[0004] Polyether polyols and polyglycerols are traditional grinding aids. Their addition can adjust the rheological properties and surface charge of the ore in the roller press, reduce viscosity due to grinding and extrusion, promote particle dispersion, and prevent particle adhesion and agglomeration on the grinding media and mill liners, thereby improving grinding efficiency. As the amount of adsorption on the material surface increases, the wear resistance decreases. At complete adsorption, the wear resistance is minimal, surface hardness decreases, and the amount of fine powder increases. The effects of polyether polyols and polyglycerols on the burnability and decomposition heat efficiency of raw materials have not been reported. Summary of the Invention

[0005] Objective of this invention: The objective of this invention is to provide a melting accelerator that addresses the problem that existing mineralizers cannot simultaneously control the setting time of cement clinker, the calcinability of raw materials, and the decomposition heat efficiency. Another objective of this invention is to propose a method for preparing the melting accelerator, thus solving the problem of how to prepare the melting accelerator. A third objective of this invention is to propose an application of the melting accelerator in the calcination of cement clinker, solving the problem of how to prepare cement clinker through calcination.

[0006] Technical solution: The present invention provides a melting accelerator comprising the following components in parts by weight: 10-25 parts grinding aid, 15-25 parts decomposition accelerator, 10-20 parts mineralizer, and 30-65 parts water; wherein the grinding aid comprises at least two of polyether polyol, polyglycerol, and sodium gluconate, and the decomposition accelerator comprises at least two of silver acetate, silver hexafluoroantimonate, and sodium nitrate.

[0007] Sodium gluconate (SGH) has the molecular formula C7H. 13 NaO8 is a commonly used salt of the heptacarboxylic acid glucoheponic acid. Similar in properties to sodium gluconate, but with a stronger chelating ability—2-3 times that of sodium gluconate under the same conditions—it exhibits strong chelating effects on various metal ions, including calcium, aluminum, and iron ions, under alkaline conditions. Furthermore, its polyhydroxyl functional group structure provides strong solid-liquid surface activity, allowing it to adsorb onto the surface of cement raw material particles, forming a solvated adsorption layer. This layer hinders the contact and aggregation of gel particles in the decomposition furnace and hot air circulation, making the raw material more likely to remain in a suspended or boiling state within the furnace. This improves the flowability of the raw material and hot air, indirectly increasing the heat exchange rate between fuel and raw material. Adding sodium glucoheponic acid to grinding aids based on polyether polyols and polyglycerol not only increases the number and types of hydroxyl functional groups but also provides excellent solvation adsorption when the raw material is in the decomposition furnace, increasing heat exchange and improving the flowability of the raw material and hot air, thus enabling better utilization of coal's thermal energy.

[0008] The effectiveness of grinding aids also depends on the addition of decomposition accelerators. During the decomposition of carbonates, the powder is in a layered accumulation state. The carbon dioxide released from the decomposition inside the powder layer has a small diffusion area, high resistance, and slow speed to diffuse into the airflow. Furthermore, the particles inside the powder layer are wrapped by a carbon dioxide gas film, resulting in a high partial pressure of carbon dioxide and requiring a high decomposition temperature. To improve the efficiency of carbonate decomposition and increase the decomposition rate, silver acetate, silver hexafluoroantimonate, and sodium nitrate are used as decomposition accelerators. These substances are easily decomposed during multiple heat exchanges in the decomposition furnace. Their vaporization process promotes the full and uniform dispersion of the gas-solid two phases, disturbs the carbon dioxide gas film layer, forms bubbles, and rapidly breaks them, allowing hot air to be drawn in smoothly, increasing heat transfer efficiency, and promoting the entire carbonate decomposition process. If decomposition accelerators are lacking, the grinding aid can only be adsorbed on the surface of the powder and cannot penetrate into the surface of the granular mineral particles inside the cement raw meal to form a solvated adsorption layer, thus greatly reducing the effectiveness of the grinding aid.

[0009] Preferably, the mineralizing agent comprises at least one of zinc sulfate and sodium hypochlorite.

[0010] The addition of traditional mineralizing components can lower the firing temperature of silicate cement clinker. In an oxidizing atmosphere, the introduction of zinc sulfate and sodium hypochlorite, being ionic compounds, can easily adhere to the surface of the material during the solid-phase reaction stage, lowering the temperature at which the liquid phase appears during clinker firing and reducing the viscosity of the liquid phase. This lowers the formation temperature of alite, improves crystal development, promotes the formation of C3S, and yields high-quality cement clinker without significantly changing the setting time compared to traditional cement clinker.

[0011] Preferably, the mineralizing agent is composed of zinc sulfate and sodium hypochlorite in a mass ratio of 20-40:40-100.

[0012] Preferably, the grinding aid is composed of polyether polyol, polyglycerol and sodium gluconate in a mass ratio of 20-40:30-70:5-35.

[0013] Preferably, the decomposition promoter is composed of silver acetate, silver hexafluoroantimonate, and sodium nitrate in a mass ratio of 25-55:10-30:20-60.

[0014] A second aspect of this invention discloses a method for preparing the above-mentioned melting accelerator, comprising the following steps:

[0015] (1) A grinding aid is prepared by mixing polyether polyol, polyglycerol and sodium gluconate; a decomposition promoter is prepared by mixing silver acetate, silver hexafluoroantimonate and sodium nitrate; a mineralizer is prepared by mixing zinc sulfate and sodium hypochlorite.

[0016] (2) A melting accelerator is prepared by mixing grinding aid, decomposition accelerator, mineralizer and water in proportion.

[0017] The third aspect of this invention discloses the application of the above-mentioned melting accelerator in the calcination of cement clinker.

[0018] The above application includes the following steps:

[0019] (1) The melting accelerator is added to the cement raw meal to obtain raw meal powder to be burned;

[0020] (2) Cement clinker is obtained by calcining raw meal powder.

[0021] Preferably, in step (1) of the above application, the amount of the melting accelerator added is 1.0-1.2 wt‰ of the cement raw meal, and the cement raw meal is dried white raw meal.

[0022] Preferably, in step (2) of the above application, the calcination conditions are calcination at 750-820℃ for 15-45 minutes, followed by calcination at 1400-1430℃ for 30-60 minutes.

[0023] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0024] This invention addresses the problem that mineralizers added during the calcination of cement clinker cannot simultaneously control the setting time of cement clinker, the calcinability of raw meal, and the decomposition heat efficiency. By rationally combining grinding aid components, decomposition promoting components, and mineralizing components, a liquid melting accelerator with low dosage and stable and uniform efficacy is prepared. This accelerator can activate the activity of cement clinker, promote carbonate decomposition, improve the calcinability of raw meal, and reduce actual coal consumption during the clinker calcination process. Detailed Implementation

[0025] The technical solution of the present invention will be further described below.

[0026] Example 1: The composition ratio and preparation method of a melting accelerator are as follows:

[0027] (1) The grinding aid is obtained by thoroughly mixing polyether polyol, polyglycerol and sodium gluconate in a mass ratio of 30:50:20;

[0028] (2) Silver acetate, silver hexafluoroantimonate and sodium nitrate were thoroughly mixed in a mass ratio of 40:20:40 to obtain a decomposition promoter;

[0029] (3) Zinc sulfate and sodium hypochlorite are mixed at a mass ratio of 30:70 to obtain a mineralizing agent;

[0030] (4) A melting promoter is prepared by mixing 18 parts grinding aid, 20 parts decomposition promoter, 15 parts mineralizer and 47 parts water.

[0031] The obtained melting accelerator was used in the calcination preparation of cement clinker, as follows:

[0032] (1) Take the raw meal powder (white raw meal) into the kiln and dry it at 105℃ for 1 hour. Add the melting accelerator into the white raw meal at 1.2wt‰ of the white raw meal and mix evenly to obtain the raw meal powder to be fired. The chemical composition of the white raw meal is shown in Table 1.

[0033] Table 1 Chemical composition of white raw material

[0034]

[0035] (2) After pressing the raw meal powder to be burned into cement raw meal test blocks and drying them, they are placed in 820℃ for calcination for 30 minutes, and then quickly placed in a high-temperature furnace for calcination at 1430℃ for 45 minutes to obtain cement clinker.

[0036] Example 2: The composition ratio and preparation method of a melting accelerator are as follows:

[0037] (1) The grinding aid is obtained by thoroughly mixing polyether polyol, polyglycerol and sodium gluconate in a mass ratio of 20:30:5;

[0038] (2) Silver acetate, silver hexafluoroantimonate and sodium nitrate were thoroughly mixed in a mass ratio of 25:10:20 to obtain a decomposition promoter;

[0039] (3) Zinc sulfate and sodium hypochlorite are mixed at a mass ratio of 20:40 to obtain a mineralizing agent;

[0040] (4) Mix 10 parts grinding aid, 15 parts decomposition promoter, 10 parts mineralizer and 30 parts water to prepare a melting promoter.

[0041] The obtained melting accelerator was used in the calcination preparation of cement clinker, as follows:

[0042] (1) Take the raw meal powder (white raw meal) into the kiln and dry it at 105℃ for 1 hour. Add the melting accelerator into the white raw meal at 1.0wt‰ of the white raw meal and mix evenly to obtain the raw meal powder to be fired. The chemical composition of the white raw meal is shown in Table 1.

[0043] (2) After pressing the raw meal powder to be burned into cement raw meal test blocks and drying them, they are placed in a furnace at 750°C for 40 minutes and then quickly placed in a high-temperature furnace at 1400°C for 60 minutes to obtain cement clinker.

[0044] Example 3: The composition ratio and preparation method of a melting accelerator are as follows:

[0045] (1) A grinding aid is obtained by thoroughly mixing polyether polyol, polyglycerol and sodium gluconate in a mass ratio of 40:70:35;

[0046] (2) Silver acetate, silver hexafluoroantimonate and sodium nitrate were thoroughly mixed in a mass ratio of 55:30:60 to obtain a decomposition promoter;

[0047] (3) Zinc sulfate and sodium hypochlorite are mixed at a mass ratio of 40:100 to obtain a mineralizing agent;

[0048] (4) A melting promoter is prepared by mixing 25 parts grinding aid, 25 parts decomposition promoter, 20 parts mineralizer and 65 parts water.

[0049] The obtained melting accelerator was used in the calcination preparation of cement clinker, as follows:

[0050] (1) Take the raw meal powder (white raw meal) into the kiln and dry it at 105℃ for 1 hour. Add the melting accelerator into the white raw meal at 1.1wt‰ of the white raw meal and mix evenly to obtain the raw meal powder to be fired. The chemical composition of the white raw meal is shown in Table 1.

[0051] (2) After pressing the raw meal powder to be burned into cement raw meal test blocks and drying them, they are calcined at 950°C for 20 minutes, and then quickly transferred to a high-temperature furnace and calcined at 1430°C for 30 minutes to obtain cement clinker.

[0052] Comparative Example 1: Everything else is the same as in Example 1, except that:

[0053] Sodium gluconate is not added in step (1).

[0054] Comparative Example 2: Everything else is the same as in Example 1, except that:

[0055] Replace sodium gluconate in step (1) with sodium gluconate.

[0056] Comparative Example 3: Everything else is the same as in Example 1, except that:

[0057] Replace the decomposition accelerator in step (4) with water.

[0058] Comparative Example 4: Everything else is the same as in Example 1, except that:

[0059] Replace silver acetate in step (2) with silver nitrate.

[0060] Comparative Example 5: Everything else is the same as in Example 1, except that:

[0061] Silver hexafluoroantimonate was replaced with silver fluoride.

[0062] Comparative Example 6: Everything else is the same as in Example 1, except that:

[0063] Silver acetate and silver hexafluoroantimonate are not added; sodium nitrate is used as the decomposition promoter only.

[0064] Comparative Example 7: Everything else is the same as in Example 1, except that:

[0065] Silver acetate and sodium nitrate are not added; only silver hexafluoroantimonate is used as a decomposition promoter.

[0066] Comparative Example 8: Everything else is the same as in Example 1, except that:

[0067] Silver hexafluoroantimonate and sodium nitrate are not added; silver acetate alone will act as a decomposition promoter.

[0068] Comparative Example 9: Everything else is the same as in Example 1, except that:

[0069] Apatite was used to replace the melting accelerator in the preparation of raw meal powder to be burned.

[0070] Comparative Example 10: Everything else is the same as in Example 1, except that:

[0071] Apatite was used to replace the melting accelerator. Apatite was added to the white raw meal at 0.75 wt% of the white raw meal to prepare raw meal powder to be burned.

[0072] To test the performance of the melting accelerator, during the calcination preparation of cement clinker in Examples 1-3 and Comparative Examples 1-10, each ash pan was filled with 1.0000 g ± 0.0050 g of the mixed raw meal powder to be calcined. After being spread evenly, the mixture was calcined at 750 °C and 820 °C for 30 min respectively, and the loss on ignition was measured. The blank group used water to replace the melting accelerator. The results are shown in Table 2:

[0073] Table 2 Results of Loss on Ignition Test

[0074]

[0075]

[0076] The raw meal powders prepared in Examples 1-3 and Comparative Examples 1-10 were pressed into cement raw meal test blocks, dried, and then calcined at 950°C for 30 minutes. They were then rapidly transferred to a high-temperature furnace and calcined at 1400°C and 1430°C. The blank group used water to replace the melting accelerator. The free calcium oxide content of each group was determined. The results are shown in Table 3.

[0077] Table 3 Results of Burnability Test

[0078]

[0079] The setting time of the cement clinker prepared in Examples 1-3 and Comparative Examples 1-10 was determined by the following method:

[0080] The reaction was conducted according to GB / T 21372-2024, "Silicate Cement Clinker". The blank control group used water to replace the melting accelerator, and the results are as follows:

[0081] Table 4. Test results of setting time of cement clinker

[0082]

[0083]

[0084] As shown in Tables 2-4, the loss on ignition and scalability of Comparative Examples 1 and 2 were significantly lower than those of Example 1, indicating that replacing or omitting sodium gluconate in the melting accelerator could not achieve a good calcination promoting effect. Only when sodium gluconate was added could the melting accelerator exhibit high calcination promoting performance. Comparative Example 1 also reflects that traditional grinding aids do not have a good calcination promoting effect. The loss on ignition and scalability of Comparative Example 3 were also significantly lower than those of Example 1, indicating that the grinding aid containing sodium gluconate relies on the decomposition accelerator to exert its calcination promoting effect.

[0085] The significantly lower loss on ignition and flammability of Comparative Examples 4-8 compared to Example 1 indicate that only when silver acetate, silver hexafluoroantimonate, and sodium nitrate are used in combination can they synergistically exert a highly efficient decomposition-promoting effect; all three are indispensable. Replacing them with other similar substances leads to a significant reduction in the performance of the melting accelerator. Furthermore, the effect of using silver acetate, silver hexafluoroantimonate, or sodium nitrate alone as a decomposition accelerator is poor, significantly lower than the effect of using the three in combination.

[0086] In Comparative Examples 9 and 10, conventional phosphate mineralizers were used as additives for calcination to prepare cement clinker. In Comparative Example 9, due to the insufficient amount of apatite, its loss on ignition and burnability were significantly lower than in Example 1, and apatite delayed both the initial and final setting times of the cement clinker. In Comparative Example 10, an excessive amount of apatite was added to improve the loss on ignition and burnability. Although the effects on loss on ignition and burnability were similar to those in Example 1, the excessive apatite further delayed the initial and final setting times of the cement clinker. Therefore, this invention further solves the application difficulties and existing problems of traditional phosphate mineralizers.

Claims

1. A melting promoter, characterized by, The cement clinker burning accelerator comprises the following components by weight: 10-25 parts of grinding aid, 15-25 parts of decomposition promoter, 10-20 parts of mineralizer, and 30-65 parts of water; the grinding aid comprises at least two of polyether polyol, polyglycerol and sodium glucoheptonate; the decomposition promoter is composed of silver acetate, silver hexafluoroantimonate and sodium nitrate in a mass ratio of 25-55:10-30:20-60.

2. The flux according to claim 1, wherein The mineralizer comprises at least one of zinc sulfate and sodium hypochlorite.

3. The flux according to claim 2, wherein The mineralizer is composed of zinc sulfate and sodium hypochlorite in a mass ratio of 20-40:40-100.

4. The flux according to claim 1, wherein The grinding aid is composed of polyether polyol, polyglycerol and sodium glucoheptonate in a mass ratio of 20-40:30-70:5-35.

5. The method of claim 1-4, wherein the melting promoter is prepared by the steps of: The method comprises the following steps: (1) mixing polyether polyol, polyglycerol and sodium glucoheptonate to prepare the grinding aid; mixing silver acetate, silver hexafluoroantimonate and sodium nitrate to prepare the decomposition promoter; and mixing zinc sulfate and sodium hypochlorite to prepare the mineralizer; (2) mixing the grinding aid, the decomposition promoter, the mineralizer and water in a certain proportion to prepare the cement clinker burning accelerator.

6. The cement clinker burning accelerator according to any one of claims 1-4 is applied in cement clinker burning.

7. Use according to claim 6, characterized in that, The method comprises the following steps: (1) mixing the cement raw material with the cement clinker burning accelerator to obtain the to-be-burned raw material powder; (2) calcining the to-be-burned raw material powder to obtain the cement clinker.

8. Use according to claim 7, characterized in that, In step (1), the mixing amount of the cement clinker burning accelerator is 1.0-1.2 wt‰ of the cement raw material, and the cement raw material is the dried white raw material.

9. Use according to claim 7, characterized in that, In step (2), the calcination condition is calcination at 750-820℃ for 15-45min, and then calcination at 1400-1430℃ for 30-60min.

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