A production method of a sulfur-resistant durable high-strength high-sulfate-resistant portland cement

Abstract

The application discloses a production method of anti-sulfur protection durable high-strength high-sulfate-resistant Portland cement, and particularly relates to the field of building materials. The specific steps are as follows: low-alkali limestone, sandstone and iron powder are screened, and after being ground and homogenized, the two are calcined in a rotary kiln to obtain clinker with a content of more than 55% and a content of less than 5%; bauxite, gypsum and limestone are prepared according to a stoichiometric ratio, and active clinker is prepared by calcining in a suspension furnace; after the two kinds of clinker and high-activity calcined metakaolin modifier are respectively ground, they are mixed and homogenized according to a proportion, and the alkali content is controlled. Through the synergistic effect of the double-clinker system and the high-activity modifier, a double structure of ettringite early skeleton and C-S-H gel dense network is constructed in the hydration process, and the sulfate resistance, strength, durability and volume stability of the cement are improved. The application is suitable for harsh corrosive environments such as marine engineering, saline-alkali land and underground tunnel.

Description

Technical Field

[0001] This invention relates to the field of building materials, and in particular to a method for producing sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement. Background Technology

[0002] In harsh environments such as marine engineering, saline-alkali land construction, underground tunnels, and water conservancy facilities, ordinary silicate cement concrete faces the severe challenge of sulfate attack. Sulfate ions react with tricalcium aluminate and calcium hydroxide in cement hydration products to form expansive ettringite and gypsum, causing enormous stress within the concrete, leading to cracking, spalling, and strength deterioration, severely shortening the structural lifespan. To address this problem, traditional technologies mainly focus on producing high sulfate-resistant silicate cement, with the core idea being to strictly limit the sulfate content in the clinker. Mineral content. However, this "single control" strategy has inherent flaws: As a key mineral contributing to early strength, a significant reduction in its content inevitably leads to slow early strength development in cement, making it difficult to meet the stringent early strength requirements of modern rapid construction. This creates a technical contradiction between achieving both high sulfate resistance and high early strength. Furthermore, existing methods using large amounts of slag, fly ash, and other admixtures to improve corrosion resistance often introduce new problems such as even lower early strength, increased shrinkage, or decreased workability. Therefore, developing a cement material that simultaneously achieves high early strength, extremely strong sulfate corrosion resistance, excellent durability, and volume stability has become a critical technical bottleneck that urgently needs to be overcome in the field of civil engineering materials.

[0003] This invention innovatively employs a dual-clinker system combining silicates and sulfoaluminates, significantly enhancing the activity and reaction efficiency of the cementitious material. Under the synergistic effect of a highly active modifier derived from calcined metakaolin, this system achieves a microstructural coupling effect between the early and rapid formation of the ettringite skeleton during hydration and the continuous filling of pores by the CSH gel. This successfully overcomes the industry's technical bottleneck of the difficulty in synergistically improving high strength, high sulfur resistance, high durability, and low shrinkage properties. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a production method for sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement, which solves the problem that it is difficult to synergistically improve high strength, high sulfur resistance, high durability and low shrinkage performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for producing sulfur-resistant, durable, high-strength, and sulfate-resistant silicate cement includes the following steps: S1: The limestone ore, volcanic ash, iron powder, low-alkali calcined metakaolin, calcium chloride, and low-alkali coal are ground by the grinding system. The raw materials are then screened by the screening system and put into the twin-shaft paddle mixer for thorough mixing. A portion of the raw materials is then placed in an X-ray fluorescence analyzer to monitor the chemical composition of the raw materials in real time and to link the grinding system to stabilize the composition of the raw materials. S2: Place the thoroughly mixed raw material from S1 into a preheater system for preheating and drying; S3: The raw meal thoroughly mixed in S2 is placed in the rotary kiln calcination system for complete calcination. A bypass venting system is installed in the rotary kiln, and the venting rate is dynamically adjusted according to the alkali content, chlorine content of the raw meal entering the kiln, and the operating conditions of the kiln system. , The kiln ash with the highest volatile alkali content should be removed and the alkali content of the clinker controlled; S4: The fully calcined clinker in S3 is quickly placed in a grate cooler to cool it rapidly. Then, the clinker is stacked using a ventilation stacking system, and the free potassium sulfate in the clinker absorbs moisture from the air and weathers and precipitates out. S5: The calcined clinker and low-alkali gypsum are thoroughly mixed, ground, and screened through a grinding system; S6: Low-alkali cement is prepared by dynamically adjusting the proportions of clinker, low-alkali gypsum, and low-alkali calcined metakaolin from S5 based on alkali content using a material selection system, and then thoroughly grinding the mixture.

[0006] Preferably, the limestone ore in S1 contains The alkali content of the ore is less than 0.5% in the exploration ore of the designated mine. The silicon content of the volcanic ash mentioned in S1 is not less than 70% and the alkali content is less than 1.0%. The alkali content of the iron powder mentioned in S1 is less than 0.8%. The alkali content of the low-alkali calcined metakaolin in S1 is less than 0.8%. The alkali content of the low-alkali coal in S1 is less than 0.5%.

[0007] Preferably, in S1, limestone ore, volcanic ash, iron powder, low-alkali calcined metakaolin, calcium chloride, and low-alkali coal are ground and then passed through a 200-mesh sieve.

[0008] Preferably, in step S1, the raw material is added to a twin-shaft paddle mixer with a rotation speed of 500-800 rpm and stirred thoroughly for 5-10 minutes.

[0009] Preferably, in S2, the raw material is placed in a preheater system at 100°C for preheating and drying.

[0010] Preferably, in step S3, the raw materials are fed into a rotary kiln calcination system at 1450–1480°C and calcined for 0.5–1 hour.

[0011] Preferably, in S3, the clinker minerals are controlled. >55%, <5%.

[0012] Preferably, in step S4, the fully combusted clinker is rapidly placed in a grate cooler with a cooling rate > 500°C / min for cooling.

[0013] Preferably, the alkali content of the low-alkali gypsum in S5 is <0.8%, and the fully calcined clinker and the low-alkali gypsum in S5 are thoroughly ground and mixed and screened through a 200-mesh sieve.

[0014] Preferably, in S6, clinker, low-alkali gypsum, and low-alkali calcined metakaolin have an alkali content of <0.6%. <3.5% ingredients.

[0015] The technical effects and advantages of the production method of sulfur-resistant, durable, high-strength, and sulfate-resistant silicate cement of this invention are as follows: 1. This invention significantly reduces the total alkali content in cement products by strictly selecting limestone, volcanic ash, iron powder and low-alkali calcined metakaolin raw materials with alkali content below the limit value, and by combining a bypass ventilation system to dynamically control the alkali circulation in the kiln. This effectively inhibits alkali-aggregate reaction and improves the long-term durability of cement in sulfate erosion environment.

[0016] 2. This invention employs a dual-clinker system consisting of high-strength silicate clinker and active calcium sulfoaluminate clinker, supplemented with highly active calcined metakaolin as a modifier, thereby achieving a balance between early strength development and high resistance to sulfate corrosion.

[0017] 3. This invention optimizes the distribution of cement particles and the hydration reaction process by grinding each component to a specific specific surface area and performing efficient homogenization treatment, thereby improving the uniformity and microstructure density of hydration products and enhancing the impermeability and mechanical properties of cement stone.

[0018] 4. This invention introduces bypass ventilation technology and adopts rapid cooling process during clinker calcination, which effectively controls the content of alkali metal oxides and free calcium oxide in clinker, and improves the mineral activity of clinker and the volume stability of cement.

[0019] 5. This invention, through real-time linkage between the online component monitoring system and the batching system, achieves dynamic and precise control of the alkali content and sulfur trioxide content in raw materials, clinker, and final cement products, ensuring the homogeneity and stability of product quality.

[0020] 6. This invention, while improving sulfate resistance, also significantly improves the volume stability and long-term durability of cement materials by adding highly active silica-alumina materials to consume calcium hydroxide and reduce drying shrinkage sources.

[0021] 7. The raw materials and process control methods used in this invention have good industrial adaptability and economy, and can realize the large-scale production of high-performance sulfate-resistant cement without significantly increasing production costs, thus having good prospects for engineering applications.

[0022] 8. This invention establishes a comprehensive quality assurance system covering the entire process from raw material selection and process control to finished product testing, forming a traceable and controllable production technology paradigm, and providing a systematic technical solution for the preparation of similar high-performance cements. Attached Figure Description

[0023] Figure 1 This is a flowchart of a production method for a sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement proposed in this invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0026] Example 1

[0027] This embodiment provides a method for producing sulfur-resistant, durable, high-strength, and sulfate-resistant silicate cement, the specific implementation steps of which include: Experimental materials: Silicate: 85 parts by weight of limestone ore ( ).

[0028] Silicon-aluminum source: 12 parts by weight of volcanic ash.

[0029] Antisulfur agent: 40 parts by weight of low-alkali gypsum ( · ).

[0030] Correction materials: 10 parts by weight of low-alkali calcined metakaolin, 3 parts by weight of iron powder ( 3 parts by weight of calcium chloride.

[0031] Fuel: 15 parts by weight of low-alkali coal.

[0032] Experimental objective: Low-alkali sulfate-resistant silicate cement was prepared by ventilation, coal addition, raw material addition, kiln calcination temperature and system, and grate cooling calcination.

[0033] Experimental steps: S1: Limestone ore, volcanic ash, iron powder, low-alkali calcined metakaolin, calcium chloride, and low-alkali coal are ground by a grinding system. The raw materials are then screened by a screening system to obtain particles smaller than 200 mesh. The raw materials are then put into a 500rpm twin-shaft paddle mixer and stirred for 5 minutes. A portion of the raw materials is then placed in an X-ray fluorescence analyzer to monitor the chemical composition of the raw materials in real time and to coordinate with the grinding system to stabilize the composition of the raw materials. S2: Place the thoroughly mixed raw material from S1 into a preheater system at 100°C for preheating and drying; S3: Place the thoroughly mixed raw meal from S2 into a rotary kiln calcination system at 1450–1480℃ and calcine for 1 hour. A bypass ventilation system is installed in the rotary kiln. The ventilation rate is dynamically adjusted based on the alkali and chlorine content of the raw meal entering the kiln and the operating conditions of the kiln system. , The kiln ash with the highest volatile alkali content should be removed and the clinker minerals controlled. >55%, Composition <5%; S4: The fully calcined clinker in S3 is rapidly placed in a grate cooler with a cooling rate of >500℃ / min to cool the clinker quickly. Then, the clinker is stacked using a ventilation stacking system, and the free potassium sulfate in the clinker absorbs moisture from the air and weathers and precipitates out. S5: The calcined clinker and low-alkali gypsum are thoroughly mixed and ground through a grinding system, and the clinker with a particle size passing through a 200-mesh sieve is screened. S6: Through a material selection system, the clinker, low-alkali gypsum, and low-alkali calcined metakaolin from S5 are selected with an alkali content of <0.6%. The alkali content is dynamically adjusted based on the data of <3.5%, and the fully ground mixture is used to prepare low-alkali cement.

[0034] Experimental results: See Tables 1 and 2 for details. Table 1: Performance Test Results of Example 1

[0035] Table 2: Chemical composition analysis results of Example 1

[0036]

[0037]

[0038] This embodiment employs a dual-clinker calcination system of silicate and sulfoaluminate clinkers, combined with highly active calcined metakaolin as a modifier. Through precise raw material proportioning, staged calcination, ultrafine grinding, and sequential composite processes, sulfate-resistant cement with excellent comprehensive performance was successfully prepared. The high-strength silicate clinker was calcined at 1450–1480℃, with controlled temperature... >55%, <5%; Activated calcium sulfoaluminate clinker is calcined at 1250–1350℃ to ensure… Highly active formulation; both are ground to a specific surface area ≥380. With ≥450 And grind to ≥800 The calcined metakaolin was compounded in a ratio of 80:10:5:5. Through multiple process controls including bypass ventilation, grate cooling, and ventilation weathering, the alkali content in the clinker was effectively reduced. Content. The final cement, with a 3-day compressive strength of 36.5 MPa and a 28-day compressive strength of 78.2 MPa, exhibited extremely high resistance to sulfate corrosion.

[0039] Example 2

[0040] This embodiment provides a method for producing sulfur-resistant, durable, high-strength, and sulfate-resistant silicate cement, the specific implementation steps of which include: Experimental materials: Silicate: 85 parts by weight of limestone ore ( ).

[0041] Antisulfur agent: 40 parts by weight of low-alkali gypsum ( · ).

[0042] Correction materials: 10 parts by weight of low-alkali calcined metakaolin, 3 parts by weight of iron powder ( 3 parts by weight of calcium chloride.

[0043] Fuel: 15 parts by weight of low-alkali coal.

[0044] Experimental objective: This study investigates the changes in sulfate resistance, early strength, and durability of cement when only silicate clinker is used.

[0045] Experimental steps: S1: Limestone ore, iron powder, low-alkali calcined metakaolin, calcium chloride, and low-alkali coal are ground by a grinding system. Raw materials with particles smaller than 200 mesh are screened by a screening system. The raw materials are then put into a 500rpm twin-shaft paddle mixer and stirred for 5 minutes. A portion of the raw materials is then placed in an X-ray fluorescence analyzer to monitor the chemical composition of the raw materials in real time and to link the grinding system to stabilize the composition of the raw materials. S2: Place the thoroughly mixed raw material from S1 into a preheater system at 100°C for preheating and drying; S3: Place the thoroughly mixed raw meal from S2 into a rotary kiln calcination system at 1450–1480℃ and calcine for 1 hour. A bypass ventilation system is installed in the rotary kiln. The ventilation rate is dynamically adjusted based on the alkali and chlorine content of the raw meal entering the kiln and the operating conditions of the kiln system. , The kiln ash with the highest volatile alkali content should be removed and the clinker minerals controlled. >55%, Composition <5%; S4: The fully calcined clinker in S3 is rapidly placed in a grate cooler with a cooling rate of >500℃ / min to cool the clinker quickly. Then, the clinker is stacked using a ventilation stacking system, and the free potassium sulfate in the clinker absorbs moisture from the air and weathers and precipitates out. S5: The calcined clinker and low-alkali gypsum are thoroughly mixed and ground through a grinding system, and the clinker with a particle size passing through a 200-mesh sieve is screened. S6: Through a material selection system, the clinker, low-alkali gypsum, and low-alkali calcined metakaolin from S5 are selected with an alkali content of <0.6%. The alkali content is dynamically adjusted based on the data of <3.5%, and the fully ground mixture is used to prepare low-alkali cement.

[0046] Experimental results: See Tables 3 and 4 for details. Table 3: Performance Test Results of Example 2

[0047] Table 4: Chemical composition analysis results of Example 2

[0048]

[0049] This embodiment investigated the overall performance of cement using only a silicate clinker system. The results showed that, in the absence of the early ettringite framework support provided by calcium sulfoaluminate clinker, the early strength development and sulfate resistance of the cement were significantly reduced. The 28-day compressive strength was 50 ± 2.5 MPa. This result confirms the limitations of a single silicate clinker system in harsh sulfate environments and further highlights the crucial role of introducing calcium sulfoaluminate clinker in constructing an early dense structure and improving sulfate resistance.

[0050] Example 3

[0051] This embodiment provides a method for producing sulfur-resistant, durable, high-strength, and sulfate-resistant silicate cement, the specific implementation steps of which include: Experimental materials: Silicate: 85 parts by weight of limestone ore ( ).

[0052] Silicon-aluminum source: 12 parts by weight of volcanic ash.

[0053] Antisulfur agent: 40 parts by weight of low-alkali gypsum ( · ).

[0054] Correction material: 3 parts by weight of iron powder ( 3 parts by weight of calcium chloride.

[0055] Fuel: 15 parts by weight of low-alkali coal.

[0056] Experimental objective: In the absence of highly active silica-alumina admixtures, the durability, sulfate resistance, and volume stability of cement change.

[0057] Experimental steps: S1: Grind limestone ore, volcanic ash, iron powder, calcium chloride, and low-alkali coal through a grinding system. Then, screen raw materials with particles smaller than 200 mesh through a screening system. The raw materials are then put into a 500rpm twin-shaft paddle mixer and stirred for 5 minutes. A portion of the raw materials is then placed in an X-ray fluorescence analyzer to monitor the chemical composition of the raw materials in real time and to link the grinding system to stabilize the composition of the raw materials. S2: Place the thoroughly mixed raw material from S1 into a preheater system at 100°C for preheating and drying; S3: Place the thoroughly mixed raw meal from S2 into a rotary kiln calcination system at 1450–1480℃ and calcine for 1 hour. A bypass ventilation system is installed in the rotary kiln. The ventilation rate is dynamically adjusted based on the alkali and chlorine content of the raw meal entering the kiln and the operating conditions of the kiln system. , The kiln ash with the highest volatile alkali content should be removed and the clinker minerals controlled. >55%, Composition <5%; S4: The fully calcined clinker in S3 is rapidly placed in a grate cooler with a cooling rate of >500℃ / min to cool the clinker quickly. Then, the clinker is stacked using a ventilation stacking system, and the free potassium sulfate in the clinker absorbs moisture from the air and weathers and precipitates out. S5: The calcined clinker and low-alkali gypsum are thoroughly mixed and ground through a grinding system, and the clinker with a particle size passing through a 200-mesh sieve is screened. S6: Through the material selection system, the clinker and low-alkali gypsum in S5 are selected with an alkali content of <0.6%. The alkali content is dynamically adjusted based on the data of <3.5%, and the fully ground mixture is used to prepare low-alkali cement.

[0058] Experimental results: See Tables 5 and 6 for details. Table 5: Performance Test Results of Example 3

[0059] Table 6: Chemical composition analysis results of Example 3

[0060]

[0061] This example investigated the effect of removing the highly active calcined metakaolin modifier from a dual-clinker system. Experimental results showed that although the synergistic effect of the silicate and calcium sulfoaluminate dual-clinker was retained, the cement's durability decreased due to the lack of highly active aluminosilicate materials to consume calcium hydroxide and replenish CSH gel. The impermeability and freeze-thaw resistance were lower than in Example 1, and the volume stability was slightly weakened. This comparison demonstrates that the highly active modifier plays an irreplaceable role in optimizing the composition of hydration products and improving the system's density and long-term durability, and is a necessary component for achieving a synergistic improvement in high sulfur resistance, high durability, and low shrinkage.

[0062] Comparative Example 1 This embodiment provides a traditional method for producing high sulfate-resistant silicate cement, which strictly limits harmful components in clinker and incorporates inert materials to reduce the reactivity of the system. Specific implementation steps include: Experimental materials: Limestone, SiO2, Al2O3, iron powder, gypsum, and granulated blast furnace slag with an alkali content of less than 0.6%.

[0063] Experimental objective: Strictly limit the incorporation of harmful components into clinker with inert materials to reduce the reactivity of the cement system.

[0064] Experimental steps: S1: The above raw materials are ground and homogenized, and then placed at about 1450℃ for clinker calcination; S2: After the clinker has cooled, grind the cement and add gypsum and other mixed materials in the required proportion; S3: The above-mentioned mixed materials are homogenized and then stored and shipped as finished products.

[0065] Experimental results: See Tables 7 and 8 for details. Table 7: Performance Test Results of Comparative Example 1

[0066] Table 8: Chemical composition analysis results of Comparative Example 1

[0067]

[0068] This comparative example uses a traditional high-sulfate-resistant cement single clinker system and conventional blending process, by strictly limiting the alkali content of raw materials and the clinker... Minerals were added, and slag was incorporated to improve corrosion resistance. Results showed that while the material possessed some sulfate resistance, its overall performance exhibited significant defects: low early and late-stage strength, poor durability, insufficient volume stability, and a lack of expansion compensation capacity. This comparative example vividly illustrates the performance imbalance caused by the "inhibiting components" in traditional methods, making it difficult to meet the synergistic requirements of high strength, high sulfur resistance, high durability, and low shrinkage.

[0069] Comparing the examples and comparative examples, Example 1 achieved an optimal balance between high strength, high sulfur resistance, high durability, and low shrinkage. Through the synergistic effect of the dual clinker system and the highly active modifier, a dual network structure of ettringite framework and CSH gel was successfully constructed, achieving comprehensive performance with high early strength, strong sulfate corrosion resistance, excellent durability, and volume stability. This makes it suitable for major engineering projects in harsh environments such as marine engineering and saline-alkali land construction. Example 2, using only a silicate clinker system, maintained basic mechanical properties, but early strength development and sulfate resistance significantly decreased, confirming the key role of calcium sulfoaluminate clinker in constructing a dense early framework and improving sulfur resistance. Example 3, after removing the highly active modifier from the dual clinker system, showed a decrease in durability and volume stability, indicating that calcined metakaolin is indispensable in optimizing the composition of hydration products and improving the system's density and long-term durability. Comparative Example 1, employing a traditional inhibitory component technology approach, exhibits some sulfate resistance, but suffers from low early and late-stage strength, poor durability, and insufficient volume stability, failing to meet the comprehensive requirements of high-performance engineering materials. Therefore, the dual clinker system and composite process provided by this invention successfully overcome traditional technological bottlenecks, offering an effective and reliable solution for preparing high-performance sulfate-resistant cement.

[0070] The above embodiments can be implemented in whole or in part by software, hardware, firmware or other arbitrary combinations. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product.

[0071] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0072] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0073] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims.

[0074] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing sulfur-resistant, durable, high-strength, and sulfate-resistant silicate cement, characterized in that, Specifically, the following steps are included: S1: The limestone ore, volcanic ash, iron powder, low-alkali calcined metakaolin, calcium chloride, and low-alkali coal are ground by the grinding system. The raw materials are then screened by the screening system and put into the twin-shaft paddle mixer for thorough mixing. A portion of the raw materials is then placed in an X-ray fluorescence analyzer to monitor the chemical composition of the raw materials in real time and to link the grinding system to stabilize the composition of the raw materials. S2: Place the thoroughly mixed raw material from S1 into a preheater system for preheating and drying; S3: The raw meal thoroughly mixed in S2 is placed in the rotary kiln calcination system for complete calcination. A bypass venting system is installed in the rotary kiln, and the venting rate is dynamically adjusted according to the alkali content, chlorine content of the raw meal entering the kiln, and the operating conditions of the kiln system. , The kiln ash with the highest volatile alkali content should be removed and the alkali content of the clinker controlled; S4: The fully calcined clinker in S3 is quickly placed in a grate cooler to cool it rapidly. Then, the clinker is stacked using a ventilation stacking system, and the free potassium sulfate in the clinker absorbs moisture from the air and weathers and precipitates out. S5: The calcined clinker and low-alkali gypsum are thoroughly mixed, ground, and screened through a grinding system; S6: Low-alkali cement is prepared by dynamically adjusting the proportions of clinker, low-alkali gypsum and low-alkali calcined metakaolin from S5 based on the alkali content through a material selection system and grinding them thoroughly.

2. The production method of sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement as described in claim 1, characterized in that, The limestone ore described in S1 contains The alkali content of the ore is less than 0.5% in the exploration ore of the designated mine. The silicon content of the volcanic ash mentioned in S1 is not less than 70% and the alkali content is less than 1.0%. The alkali content of the iron powder mentioned in S1 is less than 0.8%. The alkali content of the low-alkali calcined metakaolin in S1 is less than 0.8%. The alkali content of the low-alkali coal in S1 is less than 0.5%.

3. The production method of sulfur-resistant, durable, high-strength, and sulfate-resistant silicate cement as described in claim 1, characterized in that, In S1, limestone ore, volcanic ash, iron powder, low-alkali calcined metakaolin, calcium chloride, and low-alkali coal are ground and then passed through a 200-mesh sieve.

4. The production method of sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement as described in claim 1, characterized in that, In S1, the raw materials are added to a twin-shaft paddle mixer with a speed of 500-800 rpm and stirred thoroughly for 5-10 minutes.

5. The production method of sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement as described in claim 1, characterized in that, In S2, the raw materials are placed in a preheater system at 100°C for preheating and drying.

6. The production method of sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement as described in claim 1, characterized in that, In S3, the raw materials are fed into a rotary kiln calcination system at 1450–1480°C and calcined for 0.5–1 hour.

7. The production method of sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement as described in claim 1, characterized in that... S3 controls clinker minerals >55%, <5%.

8. The production method of sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement as described in claim 1, characterized in that, In S4, the fully combusted clinker is rapidly placed in a grate cooler with a cooling rate >500℃ / min for cooling.

9. The production method of sulfur-resistant, durable, high-strength, and sulfate-resistant silicate cement as described in claim 1, characterized in that, In S5, the alkali content of low-alkali gypsum is <0.8%. In S5, fully calcined clinker is thoroughly ground and mixed with low-alkali gypsum and then screened through a 200-mesh sieve.

10. The production method of sulfur-resistant, durable, high-strength, and high-sulfate-resistant silicate cement as described in claim 1, characterized in that, S6 uses clinker, low-alkali gypsum, and low-alkali calcined metakaolin with an alkali content of <0.6%. <3.5% ingredients.

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