High-alkali, high-activity and high-belite cement clinker as well as preparation method and application thereof

Abstract

The invention provides a high-alkali, high-activity and high-belite cement clinker as well as a preparation method and application thereof. The C2S content of the high-alkali high-activity high-belite cement clinker is 25%-80%, alkali metal elements potassium and sodium are mainly and uniformly distributed in a belite silicate mineral (C2S) crystal structure under the action of the doping agent, the prepared high-alkali high-activity belite silicate cement clinker has excellent mechanical strength, the 3d strength is 13-30 MPa, the 28d strength is 55-60 MPa, and the high-alkali high-activity belite silicate cement clinker can be used as a high-alkali high-activity high-belite silicate cement clinker. The 56d strength is 65 MPa or more, and the hydration heat is low. Meanwhile, compared with production of ordinary cement clinker, the heat consumption of clinker per ton is reduced by 5-20%, CO2 emission is reduced by about 10%, NOx emission is reduced by more than 30%, and high-alkali limestone resources are fully utilized. The high-alkali, high-activity and high-belite cement clinker and the preparation method thereof have a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of high-alkali high-activity high-belite cement clinker, and specifically relates to high-alkali high-activity high-belite cement clinker and a preparation method and application thereof. Background Art

[0002] At present, cement industry enterprises are facing the problem of serious depletion of high-quality natural resources, which not only causes the increase of production costs and the reduction of resource utilization efficiency, but also causes problems such as low clinker strength, poor adaptability of admixtures, and difficulty in controlling the workability of fresh concrete due to the use of low-grade raw materials. Therefore, in order to achieve the goals of energy conservation, emission reduction, improving resource utilization efficiency, and high-quality development of cement products in the cement industry, solving the problem of using high-alkali raw materials to prepare high-quality cement clinker and durable cement products is one of the key breakthrough directions of the cement industry. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a high-alkali, high-activity, high-belite cement clinker. The C2S content of the high-alkali, high-activity, high-belite cement clinker of the present invention is 25% to 80%, the 3d strength is 13 to 30MPa, the 28d strength is 55MPa to 60MPa, and the 56d strength is above 65MPa. The high-alkali, high-activity, high-belite cement prepared by the high-alkali, high-activity, high-belite cement clinker of the present invention having the above-mentioned properties has the advantages of high strength grade, high activity, low hydration heat, excellent cement mortar flow properties, significantly improved admixture adaptability, significantly improved resource utilization efficiency, wider application range of raw materials, and lower production cost. When the water-cement ratio is 0.5, the expansion of cement mortar can reach 175mm to 230mm, and the hydration heat is low, the stability is good, the working performance is excellent, and the various performance indicators of cement fully meet or exceed the requirements of ASTM 150M and EN197-1 standards.

[0004] In a preferred embodiment, the high-alkali, high-activity, high-belite cement clinker mainly includes the following components: 5% to 50% C3S, 35% to 80% C2S, 1% to 5% C3A, 5% to 15% C4AF, less than 1.0% free calcium oxide, 0 to 0.5% Na2O, and 0 to 1.5% K2O. By making the components of the high-alkali, high-activity, high-belite cement clinker within the above range, the advantages of high strength, high activity, low hydration heat, excellent cement mortar flow properties, and significantly improved admixture adaptability can be achieved.

[0005] In a preferred embodiment, the alkali equivalent R2O of the high-alkali, high-activity, high-belite cement clinker is 0.9-1.2%. By making the alkali equivalent R2O of the high-alkali, high-activity, high-belite cement clinker within the above range, it is possible to significantly improve resource utilization efficiency, broaden the scope of application of raw materials, reduce production costs, and have the advantages of high strength, high activity, and significantly improved admixture adaptability.

[0006] In a preferred embodiment, the high-alkali, high-activity, high-belite cement clinker is obtained by calcining raw meal, and based on the total weight of the raw meal, the oxides in the raw meal include: 37% to 45% CaO, 12% to 18% SiO2, 1.5% to 3.5% Al2O3, and 1.5% to 5% Fe2O3. In a preferred embodiment, the oxides in the raw meal further include 1.4% to 1.8% SO3.

[0007] In a preferred embodiment, the raw material comprises sandstone or high-silicon tailings, limestone, siliceous aluminum correction material and iron correction material, wherein the calcination of the raw material further comprises adding a dopant. The present application utilizes sandstone or high-silicon tailings to replace clay, high-alkali low-grade limestone, siliceous aluminum correction material and iron correction material to produce low-energy consumption, low-emission ultra-high-performance high-alkali high-activity high-belite cement clinker.

[0008] In a preferred embodiment, the limestone is high-alkali low-grade limestone, wherein the CaO content is less than 50%, the Na2O content is 0-0.5%, the K2O content is 0-1.5%, and the alkali equivalent R2O is 0.9-1.2%.

[0009] In a preferred embodiment, the siliceous and aluminous correction material is selected from one or more of fly ash, coal gangue, power plant bottom ash, coal chemical gasification slag and the like.

[0010] In a preferred embodiment, the iron correction material is selected from one or more of steel slag, iron tailings, red mud and the like.

[0011] In a preferred embodiment, the dopant includes gypsum and fluorite, and the gypsum is a mixture of one or more of anhydrous gypsum, hemihydrate gypsum or dihydrate gypsum. By using this specific dopant, calcium sulfosilicate and dicalcium silicate can form a solid solution, achieving the goals of electron cloud distribution reconstruction and multi-scale defect design of dicalcium silicate crystals, which has the advantage of significantly improving the hydration activity of dicalcium silicate.

[0012] In a preferred embodiment, the dopants of the present invention are calcium sulfate and calcium fluoride. Preferably, the calcium sulfate can be made of desulfurized gypsum, phosphogypsum, fluorgypsum, natural gypsum, etc. as raw materials. Preferably, the calcium fluoride can be a high-grade natural fluorite mineral or tailings or calcium fluoride sludge. By using a composite dopant, the goals of electron cloud distribution reconstruction, multi-scale defect design, and high alkali solid solution of dicalcium silicate crystals can be achieved, which has the advantages of significantly improving the hydration activity of dicalcium silicate, significantly improving resource utilization efficiency, broadening the scope of application of raw materials, and reducing production costs.

[0013] In a preferred embodiment, the limestone has a CaO content of less than 50%, a Na2O content of 0-0.5%, a K2O content of 0-1.5%, and an alkali equivalent R2O of 0.9-1.2%.

[0014] In a preferred embodiment, by weight ratio, the silica-alumina correction material: limestone: gypsum: fluorite = (14%~32%): (67%~85%): (0~4.5%): (0.25~1.0%).

[0015] The present invention adopts bulk industrial solid waste and high-alkali low-grade limestone resources as raw materials, which significantly improves the efficiency of resource utilization. The comprehensive blending ratio of high-silicon tailings and silicon-aluminum solid waste (fly ash, coal gangue, red mud, etc.) can reach more than 30%, which can dispose of a large amount of industrial solid waste and save natural clay resources. At the same time, iron correction materials such as iron tailings, steel slag, red mud, etc. are used, and their blending amount is as high as 15%. The calcium oxide content of high-silicon and high-aluminum high-alkali low-grade limestone can be reduced to less than 45%.

[0016] In a preferred embodiment, the raw material of the present invention consists of the following components by weight percentage: 8~15% sandstone or high silicon tailings, 78~87% limestone, 0.5~5% silicon-alumina correction material and 0.5~5% iron correction material, 3~6% raw materials containing calcium sulfate, and 0.25~5.0% raw materials containing calcium fluoride.

[0017] The present application also provides a method for preparing high-alkali, high-activity, high-belite cement clinker, the method comprising the following steps: 1) Mix sandstone or high-silicon tailings, silicon-alumina correction material, iron correction material, limestone and doping agent in proportion and grind them to form cement raw material. 2) pre-decomposing the cement raw material in a decomposition furnace, 3) The pre-decomposed material is fed into a rotary kiln for calcination and then cooled to obtain the high-alkali, high-activity, high-belite cement clinker.

[0018] In a preferred embodiment, in step 1), the particle size after grinding is such that the residue on a 0.08 mm square hole sieve is between 13% and 20%. By controlling the particle size after grinding within the above conditions, the viscosity of the material in the preheater can be reduced to avoid clogging the preheater.

[0019] In a preferred embodiment, in step 2), the temperature at the outlet of the decomposition furnace is controlled at 855-875° C. By controlling the outlet temperature of the decomposition furnace within the above range, the viscosity of the material can be reduced by lowering the temperature of the C4 feed port, thereby preventing the C4 feed port from being blocked.

[0020] And / or, in step 3), the calcination is carried out under the condition of 1350±50°C, and after the calcination, the residence time of the calcination zone is 10min~15min. By controlling the calcination temperature and the residence time of the calcination zone within the above range, it is possible to promote the diffusion of chemical elements such as potassium, sodium, and sulfur into the dicalcium silicate crystals and become a component of the lattice structure of the dicalcium silicate crystals, which has the advantages of improving the uniform distribution of potassium, sodium, and sulfur in the clinker minerals, improving the late strength of high-alkali clinker, and avoiding clinker dead burning.

[0021] The present application completely replaces clay raw materials with sandstone or high-silicon tailings, uses fly ash, coal gangue, power plant bottom slag, coal chemical gasification slag, etc. as silicon-aluminum correction materials, uses steel slag, iron tailings, red mud, etc. as iron correction materials, and uses high-alkali low-grade limestone (CaO content below 50%, Na2O content 0-0.5%, K2O content 0-1.5%, alkali equivalent R2O 0.9-1.2%) as calcium raw material and a small amount of dopant to prepare cement raw materials. A new dry cement rotary kiln process system is used, and high-performance, high-activity, high-belite silicate cement clinker is obtained by calcining at about 1350°C, which is 100°C lower than the calcination temperature of normal ordinary silicate cement clinker.

[0022] Compared with ordinary high-belite cement clinker, the high-alkali and high-activity high-belite cement clinker prepared in this application has very outstanding early strength and late strength, with a 3d strength increase of more than 5MPa, a 28d strength increase of more than 20MPa, and a 56d strength of up to 65MPa. The prepared cement has low hydration heat and excellent cement mortar flow properties. At the same time, the use of the same production line compared with the production of ordinary cement clinker shows that the heat consumption per ton of clinker is reduced by 5~20%, and reducing the amount of limestone can reduce CO2 emissions by about 10%, reducing NO x Emissions can be reduced by more than 30%, and the amount of ammonia used in SNCR can be reduced by more than 20%.

[0023] In a specific embodiment of the present invention, the method for preparing high-alkali high-activity high-belite cement clinker comprises the following steps: 1) Mix sandstone or high-silicon tailings solid waste, silicon-alumina correction material, iron correction material, high-alkali low-grade limestone, calcium sulfate and fluorite in appropriate proportions and grind them. The particle size after grinding is required to be between 13% and 20% on a 0.08mm square hole sieve to form cement raw material.

[0024] 2) The cement raw material enters the new dry process cement rotary kiln production process system equipped with a preheating and pre-decomposition system, and is pre-decomposed in the decomposition furnace. The outlet temperature of the decomposition furnace is controlled at 865±10℃.

[0025] 3) After pre-decomposition, the material enters the rotary kiln and is calcined at 1350±50℃, with a residence time of 10min~15min, and then cooled to obtain Belite cement clinker.

[0026] The present invention also provides a high-alkali high-activity high-belite cement, which is prepared from the raw material of the high-alkali high-activity high-belite cement clinker.

[0027] In a preferred embodiment, the high alkali and high activity high belite cement is prepared by the following method: adding dihydrate gypsum to high alkali and high activity high belite cement clinker and grinding them to obtain high alkali and high activity high belite cement.

[0028] In a preferred embodiment, the particle size after grinding in the preparation of the high-alkali, high-activity, high-belite cement is such that the residue on a 0.08 mm square sieve is less than 5%, and the specific surface area is 350 ± 10 m 2 / Kg.

[0029] Through the above method, the present application prepares low-energy consumption, low-emission, high-strength grade, high-performance, high-alkali, high-activity, high-belite silicate cement.

[0030] Beneficial Effects The high-alkali, high-activity, high-belite cement clinker and the preparation method thereof of the present invention have the following advantages: 1. According to the ISO 679 standard test, the prepared high-alkali, high-performance, high-alkali, high-activity, high-belite cement clinker has a C2S content of 25% to 80%, a 3d strength between 13 and 30MPa, a 28d strength of 55MPa to 60MPa, and a 56d strength of up to 65MPa. When the water-cement ratio is 0.5, the expansion of the cement mortar can reach 175mm to 230mm, and the hydration heat is low, the stability is good, the working performance is excellent, and the various performance indicators of the cement fully meet or exceed the requirements of ASTM 150M and EN197-1 standards. The concrete prepared by the high-alkali, high-performance, high-alkali, high-activity, high-belite cement prepared by the present invention has a higher 28d strength than the concrete prepared by ordinary Portland cement, which is increased by more than 10%; better durability, and the chloride ion permeability coefficient and electric flux test results are reduced by more than 50%.

[0031] 2. The present invention uses bulk industrial solid waste and high-alkali low-grade limestone resources as raw materials, which significantly improves the efficiency of resource utilization. The comprehensive blending ratio of high-silicon tailings and silicon-aluminum solid waste (fly ash, coal gangue, red mud, etc.) can reach more than 30%, which can dispose of a large amount of industrial solid waste and save natural clay resources. At the same time, iron tailings, steel slag, red mud and other iron correction materials are used, and their blending amount is as high as 15%, and the calcium oxide content of high-silicon and high-aluminum high-alkali low-grade limestone can be reduced to less than 40%.

[0032] 3. The high-alkali, high-performance, high-activity, high-belite Portland cement clinker prepared by the present invention has a sintering temperature that is about 100°C lower than that of ordinary Portland cement clinker, saves 5-10kg of standard coal per ton of clinker, reduces CO2 emissions by 50-100kg per ton of clinker, reduces NOx emissions by more than 30%, and increases hourly output by more than 8%.

[0033] 4. The high-alkali, high-performance, high-activity, high-belite Portland cement clinker prepared by the present invention realizes large-scale industrial production using a new dry cement rotary kiln process system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 FIG. 4 is a diagram showing the distribution of potassium (K) element before doping technology is adopted.

[0035] Figure 2 A diagram showing the distribution of potassium (K) element after using doping technology.

[0036] Figure 3 FIG. 4 is a diagram showing the distribution of sodium (Na) element before doping technology is adopted.

[0037] Figure 4 FIG. 4 is a diagram showing the distribution of sodium (Na) element after using doping technology. DETAILED DESCRIPTION

[0038] Based on quantum mechanics, doping theory, defect design theory, high-temperature thermodynamics theory and surface chemistry theory, and according to the high doping capacity of belite clinker mineral crystals for alkali metal elements, this application has developed an advanced technology for producing high-alkali, high-activity, high-belite cement clinker using belite solid solution alkali. Under the condition of alkali equivalent (R2O) as high as 1.2, the unfavorable characteristics of concentrated distribution of alkali metals such as potassium and sodium in cement clinker are changed, and potassium and sodium elements are evenly distributed in cement clinker, which significantly improves the performance of high-alkali cement clinker and realizes large-scale production on new dry cement production lines. The results of industrial production tests show that the performance of high-alkali, high-activity, high-belite cement produced with high-alkali limestone and high-alkali silicoalumina materials meets the standard requirements of general silicate cement, and achieves the goals of improving material performance, energy saving, carbon reduction and efficiency improvement, providing strong technical support for cement companies to achieve green and low-carbon transformation.

[0039] Compared with conventional medium (low) heat silicate cement clinker, the high-alkali, high-activity, high-belite cement clinker provided in this application has significantly improved 28d strength and significantly reduced 28d hydration heat, and has physical, mechanical and durability properties equivalent to or better than general silicate cement, indicating that it has the potential to replace ordinary silicate cement clinker on a large scale to produce general silicate cement. In order of dicalcium silicate (C2S) content from low to high, its performance indicators are as follows: Comparison of performance indicators between high alkali, high activity, high belite cement clinker and ordinary high alkali cement clinker

[0040] Compared with ordinary Portland cement clinker, in addition to excellent ultra-high gelling properties, high-alkali, high-activity, high-belite cement clinker has typical characteristics of low energy load, low resource load, and low environmental load. After the industrialization of the research and development results, based on the annual replacement of 100 million tons of ordinary Portland cement clinker and the heat consumption of 1 ton of ordinary Portland cement clinker of 110 kg standard coal, the production of high-alkali, high-activity, high-belite cement clinker can save about 10% of heat consumption, about 1.1 million tons of standard coal, and save 1.65 billion yuan in costs; CO2 emissions are reduced by up to 5 million tons, saving about 2 billion yuan in costs; the amount of ammonia water is reduced by 150,000 tons, saving 120 million yuan in costs; 10 million tons of steel slag, 12 million tons of desulfurized gypsum, and 110 million tons of high-alkali low-grade limestone (CaO content below 45%) are disposed of, reducing costs by more than 3.5 billion yuan, which not only significantly improves the efficiency of resource use, but also realizes the storage of high-grade original ecological natural resources.

[0041] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0042] Example 1 The present embodiment provides a high-alkali, high-activity, high-belite cement clinker, wherein the high-alkali, high-activity, high-belite cement clinker is obtained by calcining raw material. In terms of weight percentage, the raw material contains 10.72% of sandstone or high-silicon tailings, 78.52% of limestone, 3.05% of silicon-aluminum correction material and 3.72% of iron correction material, and 4% of dopant. Wherein, based on the total weight of the raw material, the oxides in the raw material include: 40.81% of CaO, 14.17% of SiO2, 2.27% of Al2O3, 2.95% of Fe2O3, and 1.5% of SO3.

[0043] The high-alkali, high-activity, high-belite cement clinker of the present embodiment is prepared by a method comprising the following steps: 1) Sandstone or high-silicon tailings, silicon-alumina correction material, iron correction material, limestone and doping agent are mixed in proportion and then ground. After grinding, the particle size of the 0.08mm square hole sieve residue is 15%, forming cement raw material; 2) pre-decomposing the cement raw material in a decomposition furnace; 3) The pre-decomposed material is fed into a rotary kiln for calcination and then cooled to obtain the high-alkali, high-activity, high-belite cement clinker.

[0044] By weight percentage, after quantitative analysis by XRD, the high-alkali, high-activity, high-belite cement clinker prepared in this embodiment mainly includes the following components: 45.21% C3S, 35.43% C2S, 2.34% C3A, 10.45% C4AF, 0.5% free calcium oxide, 2.35% pyroxene, and alkali equivalent (Na2O+0.658%K2O) 1.27%.

[0045] The high-alkali, high-activity, high-belite cement clinker prepared in this embodiment has a 3d strength of 27.3 MPa, a 28d strength of 56.8 MPa, a 56d strength of 65.1 MPa, and a 28d hydration heat reduction of 17%.

[0046] Example 2 The present embodiment provides a high-alkali, high-activity, high-belite cement clinker, wherein the high-alkali, high-activity, high-belite cement clinker is obtained by calcining raw meal. In terms of weight percentage, the raw meal contains 12.3% of sandstone or high-silicon tailings, 86.0% of limestone, 1.7% of silicon-aluminum-iron correction material, 1.0% of calcium fluoride sludge and 2.3% of phosphogypsum. Based on the total weight of the raw meal, the oxides in the raw meal include: 40.96% of CaO, 15.55% of SiO2, 3.43% of Al2O3, and 2.2% of Fe2O3.

[0047] The high-alkali, high-activity, high-belite cement clinker of the present embodiment is prepared by a method comprising the following steps: 1) Mix sandstone or high silicon tailings, silicon-alumina correction material, iron correction material, limestone and doping agent in proportion and grind them. The particle size after grinding should be 0.08mm square hole sieve with a residue of 13% to form cement raw material. 2) pre-decomposing the cement raw material in a decomposition furnace, 3) The pre-decomposed material is fed into a rotary kiln for calcination and then cooled to obtain the high-alkali, high-activity, high-belite cement clinker.

[0048] By weight percentage, the high-alkali, high-activity, high-belite cement clinker prepared in this embodiment is quantitatively analyzed by XRD, and the main clinker minerals include the following components: 38.2% C3S, 35.2% C2S, 3.2% C3A, 7.4% C4AF, 0.9% free calcium oxide, 3.7% pyroxene, and alkali equivalent (Na2O+0.658%K2O) 1.17%.

[0049] The high-alkali, high-activity, high-belite cement clinker prepared in this embodiment has a 3d strength of 26 MPa, a 28d strength of 58.3 MPa, a 56d strength of 67.4 MPa, and a 28d hydration heat reduction of 20%.

[0050] Example 3 The present embodiment provides a high-alkali, high-activity, high-belite cement clinker, wherein the high-alkali, high-activity, high-belite cement clinker is obtained by calcining raw material. In terms of weight percentage, the raw material contains 11.0% of sandstone or high-silicon tailings, 79.6% of limestone, 0.6% of silicon-aluminum correction material, 2.9% of iron correction material and 5.9% of dopant. Wherein, based on the total weight of the raw material, the oxides in the raw material include: 41.64% of CaO, 13.02% of SiO2, 2.82% of Al2O3, 2.26% of Fe2O3, and 1.47% of SO3.

[0051] The high-alkali, high-activity, high-belite cement clinker of the present embodiment is prepared by a method comprising the following steps: 1) Mix sandstone or high silicon tailings, silicon-alumina correction material, iron correction material, limestone and doping agent in proportion and grind them. The particle size after grinding should be 0.08mm square hole sieve with a residue of 16% to form cement raw material. 2) pre-decomposing the cement raw material in a decomposition furnace, 3) The pre-decomposed material is fed into a rotary kiln for calcination and then cooled to obtain the high-alkali, high-activity, high-belite cement clinker.

[0052] By weight percentage, the high-alkali, high-activity, high-belite cement clinker prepared in this embodiment is quantitatively analyzed by XRD, and the main clinker minerals include the following components: 34.2% C3S, 47.7% C2S, 2.3% C3A, 10.4% C4AF, 0.2% free calcium oxide, 2.7% pyroxene, and alkali equivalent (Na2O+0.658%K2O) 0.97%.

[0053] The high-alkali, high-activity, high-belite cement clinker prepared in this embodiment has a 3d strength of 21.5 MPa, a 28d strength of 62.3 MPa, a 56d strength of 70.4 MPa, and a 28d hydration heat reduction of 25%.

[0054] Comparative Example 1 This comparative example provides a high-belite cement clinker, wherein the high-belite cement clinker is obtained by calcining raw meal. In terms of weight percentage, the raw meal contains 13.3% of sandstone or high-silicon tailings, 87.0% of limestone, and 3.0% of silicon-aluminum-iron correction material. Based on the total weight of the raw meal, the oxides in the raw meal include: 40.96% of CaO, 15.55% of SiO2, 3.43% of Al2O3, and 2.2% of Fe2O3.

[0055] The clinker of this comparative example is prepared by a method comprising the following steps: 1) Mix sandstone or high silicon tailings, silicon-alumina correction material, iron correction material, limestone and doping agent in proportion and grind them. The particle size after grinding should be 0.08mm square hole sieve with a residue of 13% to form cement raw material. 2) pre-decomposing the cement raw material in a decomposition furnace, 3) The pre-decomposed material is fed into a rotary kiln for calcination and then cooled to obtain the high-belite cement clinker.

[0056] By weight percentage, after quantitative analysis by XRD, the high-belite cement clinker prepared in this comparative example mainly comprises the following components: 38.2% C3S, 35.2% C2S, 3.2% C3A, 7.4% C4AF, 1.2% free calcium oxide, and alkali equivalent (Na2O+0.658%K2O) 1.17%.

[0057] The high-belite cement clinker prepared in this comparative example has a 3d strength of 20 MPa, a 28d strength of 32.1 MPa, and a 56d strength of 38.5 MPa.

[0058] Comparative Example 2 This comparative example provides a high-belite cement clinker, wherein the high-belite cement clinker is obtained by calcining raw meal. In terms of weight percentage, the raw meal contains 12.3% of sandstone or high-silicon tailings, 86.0% of limestone, 1.7% of silicon-aluminum-iron correction material, 1.0% of calcium fluoride sludge and 2.3% of phosphogypsum. Based on the total weight of the raw meal, the oxides in the raw meal include: 40.96% of CaO, 15.55% of SiO2, 3.43% of Al2O3, and 2.2% of Fe2O3.

[0059] The high-belite cement clinker of this comparative example is prepared by a method comprising the following steps: 1) Mix sandstone or high silicon tailings, silicon-alumina correction material, iron correction material, limestone and doping agent in proportion and grind them. The particle size after grinding should be 0.08mm square hole sieve with a residue of 13% to form cement raw material. 2) pre-decomposing the cement raw material in a decomposition furnace, 3) The pre-decomposed material is fed into a rotary kiln for calcination and then cooled to obtain the high-belite cement clinker.

[0060] By weight percentage, after quantitative analysis by XRD, the high-alkali, high-activity, high-belite cement clinker prepared in this comparative example mainly comprises the following components: 38.2% C3S, 35.2% C2S, 3.2% C3A, 7.4% C4AF, 0.9% free calcium oxide, and alkali equivalent (Na2O+0.658%K2O) 1.15%.

[0061] The high-belite cement clinker prepared in this comparative example has a 3d strength of 18.0 MPa, a 28d strength of 39.8 MPa, and a 56d strength of 44.1 MPa.

[0062] Comparative Example 3 This comparative example provides a high-belite cement clinker, wherein the high-alkali and high-activity high-belite cement clinker is obtained by calcining raw meal. In terms of weight percentage, the raw meal contains 13.0% of sandstone or high-silicon tailings, 82.8% of limestone, 1.3% of silicon-aluminum correction material, and 2.9% of iron correction material. Based on the total weight of the raw meal, the oxides in the raw meal include: 41.64% of CaO, 13.02% of SiO2, 2.82% of Al2O3, 2.26% of Fe2O3, and 1.47% of SO3.

[0063] The high-alkali, high-activity, high-belite cement clinker of this comparative example is prepared by a method comprising the following steps: 1) Mix sandstone or high silicon tailings, silicon-alumina correction material, iron correction material, limestone and doping agent in proportion and grind them. The particle size after grinding should be 0.08mm square hole sieve with a residue of 16% to form cement raw material. 2) pre-decomposing the cement raw material in a decomposition furnace, 3) The pre-decomposed material is fed into a rotary kiln for calcination and then cooled to obtain the high-belite cement clinker.

[0064] By weight percentage, the high-alkali, high-activity, high-belite cement clinker prepared in this comparative example is quantitatively analyzed by XRD, and the main clinker minerals include the following components: 34.2% C3S, 47.7% C2S, 2.3% C3A, 10.4% C4AF, 0.2% free calcium oxide, 2.7% pelargonite, and alkali equivalent (Na2O+0.658%K2O) 0.97%.

[0065] The high-alkali, high-activity, high-belite cement clinker prepared in this comparative example has a 3d strength of 13.4 MPa, a 28d strength of 29.8 MPa, and a 56d strength of 35.4 MPa.

[0066] It can be seen that the high-alkali, high-activity, high-belite cement clinker of the present invention has very outstanding early strength and late strength, with a 3d strength increase of more than 5MPa, a 28d strength increase of more than 20MPa, and a 56d strength of up to 65MPa. At the same time, the use of the same production line compared with the production of ordinary cement clinker shows that the heat consumption per ton of clinker is reduced by 5-20%, and reducing the amount of limestone can reduce CO2 emissions by about 10%, reduce NOx emissions by more than 30%, and reduce SNCR ammonia water consumption by more than 20%. It can be seen that the method of this application is environmentally friendly, simple, and has broad market prospects.

[0067] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A high-alkali, high-activity, high-belite cement clinker, characterized in that: The high-alkali, high-activity, high-belite cement clinker has a C2S content of 25% to 80%, a 3d strength of 13 to 30 MPa, a 28d strength of 55 MPa to 60 MPa, and a 56d strength of more than 65 MPa.

2. A high-alkali, high-activity, high-belite cement clinker, characterized in that: The high-alkali, high-activity, high-belite cement clinker comprises the following components by weight percentage: 5%~50% C3S, 35%~80% C2S, 1%~5% C3A, 5%~15% C4AF, less than 1.0% free calcium oxide, 0~0.5% Na2O, and 0~1.5% K2O, Among them, the alkali equivalent R2O of the high-alkali, high-activity and high-belite cement clinker is 0.9-1.2%.

3. A high-alkali, high-activity, high-belite cement clinker, characterized in that: The high-alkali, high-activity, high-belite cement clinker is obtained by calcining raw materials. Based on the total weight of the raw materials, the oxides in the raw materials include: 37% to 45% CaO, 12% to 18% SiO2, 1.5% to 3.5% Al2O3, and 1.5% to 5% Fe2O3.

4. The high-alkali, high-activity, high-belite cement clinker according to claim 3, characterized in that: The raw material comprises sandstone or high silicon tailings, limestone, silicon-alumina correction material and iron correction material, wherein the calcination of the raw material further comprises adding a dopant, Wherein, the dopant comprises gypsum and fluorite, and the gypsum is a mixture of one or more of anhydrous gypsum, hemihydrate gypsum or dihydrate gypsum; Preferably, the limestone has a CaO content of less than 50%, a Na2O content of 0-0.5%, a K2O content of 0-1.5%, and an alkali equivalent R2O of 0.9-1.2%.

5. The high-alkali, high-activity, high-belite cement clinker according to claim 4, characterized in that: By weight ratio, silica-alumina correction material: limestone: gypsum: fluorite = (14%~32%): (67%~85%): (0~4.5%): (0.25~1.0%).

6. The high-alkali, high-activity, high-belite cement clinker according to claim 4, characterized in that: The raw material consists of the following components by weight percentage: 8~15% sandstone or high silicon tailings, 78~87% limestone, 0.5~5% silicon-alumina correction material and 0.5~5% iron correction material, 3~6% raw materials containing calcium sulfate, and 0.25~5.0% raw materials containing calcium fluoride.

7. A method for preparing the high-alkali, high-activity, high-belite cement clinker according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: 1) Mix sandstone or high-silicon tailings, silicon-alumina correction material, iron correction material, limestone and doping agent in proportion and grind them to form cement raw material. 2) pre-decomposing the cement raw material in a decomposition furnace, 3) The pre-decomposed material is fed into a rotary kiln for calcination and then cooled to obtain the high-alkali, high-activity, high-belite cement clinker.

8. The method according to claim 7, characterized in that In step 1), the particle size after grinding is such that the residue on a 0.08 mm square hole sieve is between 13% and 20%.

9. The method according to claim 7 or 8, characterized in that: In step 2), the temperature at the outlet of the decomposition furnace is controlled at 855-875°C; And / or, in step 3), the calcination is carried out at 1350±50° C., and after the calcination, the residence time of the sintering zone is 10 min to 15 min.

10. A high-alkali, high-activity, high-belite cement, characterized in that: Made from raw materials including the high-alkali, high-activity, high-belite cement clinker as described in any one of claims 1 to 6; Preferably, the high alkali and high activity high belite cement is prepared by the following method: adding dihydrate gypsum to the high alkali and high activity high belite cement clinker described in any one of claims 1 to 6 for grinding to obtain the high alkali and high activity high belite cement.

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