Method for preparing low-carbon green cementing agent by coal-based solid waste synergistic activation

Abstract

The application discloses a method for preparing a low-carbon green cementing agent by activating coal-based solid waste in cooperation, and belongs to the field of solid waste resource utilization. The cementing agent is composed of 25-45 parts of coal gangue powder, 20-40 parts of fly ash, 15-35 parts of water slag powder, 3-12 parts of desulfurization gypsum and 5-10 parts of cement. Each component is prepared through premixing and mixing. Early activation is provided by low-dosage cement, desulfurization gypsum controls the generation of ettringite, and the coal gangue powder, the fly ash and the water slag powder cooperatively provide active silicon aluminum and hydraulic components, so as to form a multi-phase cementing structure of hydrated calcium silicate, aluminum silicate and ettringite. The cementing agent has a 28d compressive strength of more than 32.5 MPa, can be applied to mine filling, road base stabilization, industrial solid waste solidification and low-carbon building material preparation, and has the advantages of low carbon, low cost and high solid waste utilization rate.

Description

Technical Field

[0001] This invention belongs to the technical field of coal-based solid waste resource utilization and low-carbon cementitious materials, and particularly relates to a method for preparing low-carbon green cementitious agents by synergistic activation of coal-based solid waste. Background Technology

[0002] Coal gangue, fly ash, slag, and desulfurization gypsum are major solid wastes generated during coal mining and combustion, blast furnace ironmaking, and wet flue gas desulfurization in coal-fired power plants, respectively. These four types of waste are generated in large quantities, have long storage periods, and exhibit significant differences in composition. Long-term storage not only occupies substantial land resources, but the soluble salts, residual carbon, and potentially harmful components within these wastes continuously migrate into surrounding soil and water bodies through rainwater leaching, posing significant ecological and environmental risks. Promoting the transformation of coal-based solid waste from low-value storage to high-value material utilization has become an urgent need for the green and low-carbon development of the coal and coal chemical industries.

[0003] The demand for cementitious materials is enormous in engineering fields such as mine backfilling, road base stabilization, industrial solid waste solidification, soft soil solidification, grouting reinforcement, and low-carbon building material preparation. While traditional cementitious binders offer advantages such as high early strength and good construction adaptability, their large clinker consumption, high carbon emissions, and high raw material costs make it difficult to balance engineering economics and low-carbon goals in large-scale solid waste treatment scenarios. Existing technologies include partial replacement of cement with fly ash, coal gangue, or slag; however, single coal-based solid waste generally suffers from insufficient activity, large compositional fluctuations, and low early strength. In untreated coal gangue, the silica-alumina phase exists primarily in stable mineral forms with weak reactivity; fly ash exhibits slow early reaction; while water slag has a high glass phase content, its early activity is insufficient when used alone, requiring activation in an alkaline environment to effectively participate in the cementation reaction; and desulfurized gypsum has a high calcium sulfate content, which can easily lead to volume expansion if the dosage is uncontrolled. The aforementioned issues collectively limit the upper limit of the dosage of coal-based solid waste in the binder system, making it difficult to simultaneously improve the utilization rate of solid waste and the cementing performance.

[0004] Existing technologies often employ simple mixing of coal-based solid waste and cementing components, lacking synergistic regulation tailored to the varying reactivity of different solid waste components. This results in insufficient synergistic effects among active silica-alumina components, hydrated calcium sources, and auxiliary activating components, impacting the reactivity and strength development of the cementing system. Therefore, it is necessary to enhance the reactivity of solid waste materials and promote cementitious product formation through multi-source coal-based solid waste compounding, activation of active components, and synergistic regulation of cementing components. This would reduce cement clinker usage, improve the resource utilization level of solid waste, and simultaneously enhance the mechanical properties and engineering application adaptability of cementitious agents. Summary of the Invention

[0005] To address the problems of poor synergy among components, high cement dosage, and insufficient cementitious performance in existing coal-based solid waste binders, this invention provides a method for preparing a low-carbon, green binder through synergistic activation of coal-based solid waste. This binder is prepared by mechanical grinding, component compounding, and homogenization mixing, using coal gangue powder, fly ash, slag powder, desulfurized gypsum, and low-dosage cement as the main components. Coal gangue powder provides active silica-alumina components, fly ash improves particle filling and participates in later pozzolanic reactions, slag powder provides a potential source of hydraulic activity, desulfurized gypsum exerts a sulfate-regulating effect to promote ettringite formation, and low-dosage cement provides early hydration activation and calcium source supplementation. The synergistic effect of these components promotes the simultaneous formation of various cementitious products, such as hydrated calcium silicate gel, hydrated calcium aluminosilicate gel, aluminosilicate gel, and ettringite, thereby significantly reducing cement dosage while achieving high-value utilization of coal-based solid waste and effectively improving engineering cementitious performance.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A low-carbon green binder comprises the following components by weight: 25-45 parts coal gangue powder, 20-40 parts fly ash, 15-35 parts water slag powder, 3-12 parts desulfurized gypsum, and 5-10 parts cement.

[0007] Further, it includes the following components by weight: 30-40 parts coal gangue powder, 25-35 parts fly ash, 18-28 parts water slag powder, 5-10 parts desulfurized gypsum, and 5-8 parts cement.

[0008] Furthermore, the coal gangue powder is obtained by crushing, drying, removing impurities, screening, and mechanically grinding coal gangue, and has a specific surface area of ​​350-750 m². 2 / kg.

[0009] Furthermore, the fly ash is Grade I fly ash and / or Grade II fly ash.

[0010] Furthermore, the water slag powder is a powder obtained by drying, grinding, and screening granulated blast furnace slag, with a specific surface area of ​​400-900 m². 2 / kg.

[0011] Furthermore, the desulfurized gypsum is flue gas desulfurization gypsum, hemihydrate desulfurization gypsum, or desulfurized gypsum powder that has been dried and ground.

[0012] Furthermore, the cement is ordinary Portland cement.

[0013] The present invention also provides a method for preparing a low-carbon green binder by co-activation of coal-based solid waste, comprising the following steps: premixing coal gangue powder, fly ash and water slag powder, and then adding desulfurized gypsum and cement to mix, thereby obtaining the low-carbon green binder.

[0014] This invention also provides the application of a low-carbon green binder in mine filling, road base stabilization, industrial solid waste solidification, and low-carbon building material preparation.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: This invention uses coal gangue powder and other coal-based solid wastes, along with low-dosage cement, as main raw materials. While ensuring cementing performance, it increases the proportion of coal-based solid wastes used and reduces the amount of traditional cement. The coal gangue powder is not calcined; it undergoes only pretreatment through crushing, impurity removal, screening, and mechanical grinding. The process is simple, energy consumption is low, and it is suitable for large-scale production. During the use of the cementitious agent, cement provides early strength and a reaction environment, while slag powder, fly ash, and coal gangue powder gradually participate in the cementing reaction. Desulfurized gypsum regulates the formation of ettringite, resulting in a relatively stable solidified structure. This low-carbon, green cementitious agent has a wide range of raw material sources and a simple preparation process. It can be used in mine backfilling, road base stabilization, industrial solid waste solidification, and low-carbon building material preparation, demonstrating significant engineering application value. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the synergistic activation mechanism of coal-based solid waste composite powder in the low-carbon green binder of the present invention; Figure 2 This is a schematic diagram of the hydration reaction product structure of the low-carbon green binder of the present invention; Figure 3 These are schematic diagrams showing the physical state of the low-carbon green binder prepared in Examples 1 (right) and 2 (left) of the present invention. Detailed Implementation

[0017] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0018] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0019] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0020] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0021] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0022] This invention provides a low-carbon, green binder comprising the following components by weight: 25-45 parts coal gangue powder, 20-40 parts fly ash, 15-35 parts water slag powder, 3-12 parts desulfurized gypsum, and 5-10 parts cement. Preferably, the composition is: 30-40 parts coal gangue powder (e.g., 30, 35, or 40 parts), 25-35 parts fly ash (e.g., 25, 30, or 35 parts), 18-28 parts water slag powder (e.g., 20, 22, or 23 parts), 5-10 parts desulfurized gypsum (e.g., 5, 7, or 8 parts), and 5-8 parts cement (e.g., 6 or 7 parts).

[0023] In some preferred embodiments of the present invention, the coal gangue powder is obtained by crushing, drying, removing impurities, screening, and mechanically grinding coal gangue without calcination. The specific surface area after grinding is 350-750 m². 2 / kg (e.g., 520m) 2 / kg, 600m 2 / kg or 680m 2 / kg). Mechanical grinding improves the particle size and surface defect level of coal gangue, allowing it to gradually participate in the cementitious reaction under the alkaline environment formed by cement hydration and the action of calcium source, forming a synergistic cementitious structure with fly ash, slag powder and desulfurized gypsum during the hydration reaction.

[0024] In some preferred embodiments of the present invention, the fly ash is Grade I fly ash, Grade II fly ash, or a mixture of both, used to provide glassy aluminosilicate active components and improve the particle size distribution and filling effect of the binder. Exemplarily, Grade II fly ash is selected in the following embodiments of the present invention.

[0025] In some preferred embodiments of the present invention, the slag powder is a powder obtained by drying, grinding and screening granulated blast furnace slag, with a specific surface area of ​​400-900 m² after grinding. 2 / kg (e.g., 460m) 2 / kg, 480m 2 / kg or 500m 2 / kg), used to provide potential hydraulic reactive components.

[0026] In some preferred embodiments of the present invention, the desulfurized gypsum is flue gas desulfurization gypsum, hemihydrate desulfurization gypsum, or desulfurized gypsum powder that has been dried and ground, used to provide sulfate ions and promote the formation of ettringite.

[0027] In some preferred embodiments of the present invention, the cement is ordinary silicate cement, silicate cement or slag silicate cement, and the amount added is 5-8% of the total mass of the low-carbon green binder. The cement acts as a low-dosage hydration activating component and early strength source in the binder system. Through the alkaline environment and calcium source generated by cement hydration, it promotes the active silica-alumina components in coal gangue powder, fly ash and water slag powder to participate in the cementation reaction, and together with desulfurized gypsum, promotes the formation of hydrated calcium silicate gel, hydrated calcium aluminosilicate gel, aluminosilicate gel and ettringite.

[0028] The present invention also provides a method for preparing a low-carbon green binder by co-activation of coal-based solid waste, comprising the following steps: premixing coal gangue powder, fly ash and water slag powder for 5 minutes, then adding desulfurized gypsum and cement and mixing for 8 minutes to obtain the low-carbon green binder.

[0029] The low-carbon green binder provided by this invention comprises components that, after grinding, metering, mixing, and hydration reaction, form a low-carbon green binder mainly composed of hydrated calcium silicate gel, hydrated calcium aluminosilicate gel, aluminosilicate gel, and ettringite. This binder can reduce cement usage, improve the utilization rate of coal-based solid waste, and is suitable for applications such as mine backfilling, road base stabilization, industrial solid waste solidification, and the preparation of low-carbon building materials.

[0030] The preparation method of this low-carbon green binder includes the following steps: S1. The coal gangue is crushed, dried, impurities removed and screened to obtain coal gangue raw material; S2. The coal gangue raw material obtained in step S1 is mechanically ground to obtain coal gangue powder; S3. The water slag is dried, ground, and sieved to obtain water slag powder; S4. Measure the coal gangue powder, fly ash, water slag powder, desulfurization gypsum and cement according to the proportion; S5. The components measured in step S4 are premixed, forced mixed and homogenized to obtain a coal-based solid waste synergistic activation low-carbon green binder.

[0031] In step S1, the impurity removal process includes one or more of manual sorting, air separation, magnetic separation, or sieving to remove metallic iron parts, wood chips, plastics, mud, plant residues, and other visible foreign impurities from the coal gangue. Preferably, the mass content of visible foreign impurities in the coal gangue after impurity removal is no higher than 1.0%.

[0032] In step S1, the screening process is used to remove excessively large particles and insufficiently crushed lumps. Preferably, the crushed coal gangue is screened to a particle size of no more than 5 mm. The material oversize is returned to the crushing process for further processing, while the material undersize enters the mechanical grinding process.

[0033] In step S2, mechanical grinding can be performed using one or more of ball mills, vertical mills, vibratory mills, or planetary mills. The grinding time is 10-120 minutes, and the specific surface area of ​​the coal gangue powder after grinding is 350-750 m². 2 / kg. Coal gangue powder is not calcined; instead, it is mechanically ground to improve the particle size and surface defects, enabling it to form a synergistic cementing structure with fly ash, slag powder, desulfurization gypsum, and cement during subsequent hydration reactions.

[0034] In step S3, the slag powder is a powder obtained by drying, grinding, and screening granulated blast furnace slag, with a specific surface area of ​​400-900 m² after grinding. 2 / kg.

[0035] In step S5, it is advisable to first mix the coal gangue powder, fly ash and water slag powder, and then add desulfurized gypsum and cement for a second mixing. The mixing time is 3-20 minutes to obtain a uniform and stable powder-type low-carbon green binder.

[0036] In use, the low-carbon green binder is mixed with water or water-containing solid waste slurry to form a cemented slurry with a water-to-binder ratio of 0.45-0.50. After undergoing cement hydration reaction, potential hydraulic reaction of slag, fly ash pozzolanic reaction, and sulfate regulation reaction of desulfurized gypsum, the cemented slurry forms a solidified structure with hydrated calcium silicate gel, hydrated calcium aluminosilicate gel, aluminosilicate gel, and ettringite as the main cementing products.

[0037] The low-carbon green binder prepared using the above method can be applied in mine backfilling, road base stabilization, industrial solid waste solidification, and low-carbon building material preparation. In mine backfilling, the low-carbon green binder can be mixed with tailings, coal gangue powder, or other water-containing solid waste slurries to form backfill materials with certain fluidity and post-consolidation strength. In road base stabilization, the low-carbon green binder can be mixed with aggregates and water to improve the overall stability of the base material and the interparticle bonding ability. In industrial solid waste solidification, the low-carbon green binder can improve the consolidation stability of solid waste particles through gel encapsulation, pore filling, and sulfate regulation. In low-carbon building material preparation, the low-carbon green binder can serve as a partial substitute for traditional cement, reducing cement usage and increasing the resource utilization rate of coal-based solid waste.

[0038] Figure 1 This is a schematic diagram illustrating the synergistic activation mechanism of coal-based solid waste composite powder in the low-carbon green binder of this invention. It shows the process by which coal gangue powder, fly ash, slag powder, desulfurization gypsum, and cement form a synergistic cementitious structure during the hydration reaction.

[0039] Figure 2 This is a schematic diagram of the hydration reaction products of the low-carbon green binder of the present invention, showing that hydrated calcium silicate gel, hydrated calcium aluminosilicate gel, aluminosilicate gel and ettringite form a filling, encapsulating and bridging structure between particles.

[0040] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0041] Unless otherwise specified, the term "parts" in this invention refers to parts by weight.

[0042] The coal gangue used in the embodiments and comparative examples of this invention was provided by Difuyuan (Jixi) Technology Co., Ltd., and was used after being crushed, dried, cleaned, screened and mechanically ground; the fly ash was provided by Heilongjiang Lianshun Biotechnology Co., Ltd., and Grade II fly ash was selected; the granulated blast furnace slag was provided by Heilongjiang Jianlong Steel Co., Ltd., and was dried and ground to obtain slag powder; the ordinary silicate cement and desulfurization gypsum were purchased from the market and were produced in Liaocheng, Shandong.

[0043] The technical solution of the present invention will be further illustrated by the following embodiments.

[0044] Example 1 A method for preparing a low-carbon, green binder, comprising the following steps: S1. The coal gangue is crushed, dried, impurity removed, screened, and mechanically ground to obtain a particle size ≤5mm and a specific surface area of ​​520m². 2 / kg of coal gangue powder; S2. The slag is dried, ground, and sieved to obtain a specific surface area of ​​480 m².2 / kg water slag powder; S3. Premix 35 parts coal gangue powder, 30 parts fly ash, and 22 parts water slag powder for 5 minutes, then add 7 parts desulfurized gypsum and 6 parts cement and mix for 8 minutes to obtain a powder-type low-carbon green binder.

[0045] After preparation and curing according to GB / T 17671 "Test Method for Strength of Cement Mortar (ISO Method)", the 7-day compressive strength of this low-carbon green binder is 21.6 MPa, and the 28-day compressive strength is 34.2 MPa. The results indicate that this binder can achieve the strength level of a 32.5 grade cementitious material under low cement content conditions, and can be used for the preparation of road base stabilization materials.

[0046] Example 2 A method for preparing a low-carbon, green binder, comprising the following steps: S1. The coal gangue is crushed, dried, impurity removed, screened, and mechanically ground to obtain a particle size ≤5mm and a specific surface area of ​​600m². 2 / kg of coal gangue powder; S2. The slag is dried, ground, and sieved to obtain a specific surface area of ​​500 m². 2 / kg water slag powder; S3. Premix 30 parts coal gangue powder, 35 parts fly ash, and 20 parts water slag powder for 10 minutes, then add 8 parts desulfurized gypsum and 7 parts cement and mix for 5 minutes to obtain a powder-type low-carbon green binder.

[0047] After preparation and curing in accordance with GB / T 17671 "Test Method for Strength of Cement Mortar (ISO Method)", the 7-day compressive strength of this low-carbon green binder is 20.8 MPa and the 28-day compressive strength is 33.7 MPa.

[0048] Figure 3 These are schematic diagrams showing the physical state of the low-carbon green binder prepared in Examples 1 (right) and 2 (left) of the present invention.

[0049] Application Example 1 The low-carbon green binder prepared in Example 2 was used for mine backfilling. The specific steps were as follows: the binder was mixed with tailings at a mass ratio of 12:88, with the water-binder ratio controlled at 0.50, to obtain a backfill slurry. The slurry had a fluidity of 220 mm, and after curing for 28 days, the compressive strength of the consolidated backfill was 3.4 MPa. The results show that this binder can meet the requirements of mine backfilling for fluidity, pumpability, and post-consolidation strength.

[0050] Example 3 A method for preparing a low-carbon, green binder, comprising the following steps: S1. The coal gangue is crushed, dried, impurity removed, screened, and mechanically ground to obtain a particle size ≤5mm and a specific surface area of ​​680m². 2 / kg of coal gangue powder; S2. The slag is dried, ground, and sieved to obtain a specific surface area of ​​460 m². 2 / kg water slag powder; S3. Premix 40 parts coal gangue powder, 25 parts fly ash, and 23 parts water slag powder for 12 minutes, then add 5 parts desulfurized gypsum and 7 parts cement and mix for 8 minutes to obtain a powder-type low-carbon green binder.

[0051] After preparation and curing in accordance with GB / T 17671 "Test Method for Strength of Cement Mortar (ISO Method)", the 7-day compressive strength of this low-carbon green binder is 22.4 MPa and the 28-day compressive strength is 34.8 MPa.

[0052] Application Example 2 The low-carbon green binder prepared in Example 3 was used for industrial solid waste solidification. The specific steps were as follows: the binder was mixed with coal gangue solid waste at a mass ratio of 10:90, the water-binder ratio was controlled at 0.50, and after curing for 28 days, the compressive strength of the solidified body was 2.8 MPa. The results show that this binder can form a stable solidified structure under low cement content conditions and can be used for industrial solid waste solidification treatment.

[0053] Comparative Example 1 A method for preparing a binder, comprising the following steps: S1. The coal gangue is crushed, dried, impurity removed, screened, and mechanically ground to obtain a particle size ≤5mm and a specific surface area of ​​510m². 2 / kg of coal gangue powder; S2. The slag is dried, ground, and sieved to obtain a specific surface area of ​​470 m². 2 / kg water slag powder; S3. Mix 45 parts coal gangue powder, 35 parts fly ash, and 20 parts water slag powder for 10 minutes to obtain a binder.

[0054] After preparation and curing according to GB / T 17671 "Test Method for Strength of Cement Mortar (ISO Method)", the 7-day compressive strength of this cementitious material is 9.8 MPa, and the 28-day compressive strength is 22.5 MPa. Compared with Example 1, this cementitious material did not contain a low amount of cement and desulfurized gypsum, resulting in insufficient early reaction and a 28-day compressive strength lower than 32.5 MPa, failing to reach the strength level of a 32.5 grade cementitious material.

[0055] Comparative Example 2 A method for preparing a binder, comprising the following steps: S1. The coal gangue is crushed, dried, impurity removed, screened, and mechanically ground to obtain a particle size ≤5mm and a specific surface area of ​​580m². 2 / kg of coal gangue powder; S2. The slag is dried, ground, and sieved to obtain a specific surface area of ​​490 m². 2 / kg water slag powder; S3. Mix 39 parts coal gangue powder, 39 parts fly ash, 19 parts water slag powder and 3 parts cement for 10 minutes to obtain a binder.

[0056] After preparation and curing in accordance with GB / T 17671 "Test Method for Strength of Cement Mortar (ISO Method)", the 7-day compressive strength of this cementitious material is 12.6 MPa and the 28-day compressive strength is 25.8 MPa.

[0057] Comparative Application Example 1 The binder prepared in Comparative Example 2 was used for mine backfilling. The specific steps were as follows: the binder was mixed with tailings at a mass ratio of 12:88, with a water-cement ratio controlled at 0.45. The resulting slurry had a fluidity of 175 mm, and after curing for 28 days, the compressive strength of the backfilled solidified body was 2.1 MPa. Compared to Example 2, this binder lacks the sulfate-regulating effect of desulfurized gypsum, has a lower cement content, and its slurry fluidity and later-stage consolidation strength are both lower than those of the binder of this invention.

[0058] Comparative Example 3 A method for preparing a binder, comprising the following steps: S1. The coal gangue is crushed, dried, impurity removed, screened, and mechanically ground to obtain a particle size ≤5mm and a specific surface area of ​​660m². 2 / kg of coal gangue powder; S2. The slag is dried, ground, and sieved to obtain a specific surface area of ​​450 m². 2 / kg water slag powder; S3. Mix 50 parts coal gangue powder, 30 parts fly ash, 10 parts water slag powder and 10 parts cement for 12 minutes to obtain a binder.

[0059] After preparation and curing in accordance with GB / T 17671 "Test Method for Strength of Cement Mortar (ISO Method)", the 7-day compressive strength of this cementitious material is 15.4 MPa and the 28-day compressive strength is 28.6 MPa.

[0060] Comparative Application Example 2 The binder prepared in Comparative Example 3 was used for industrial solid waste solidification. The specific steps were as follows: the binder was mixed with coal gangue solid waste at a mass ratio of 10:90, with a water-to-binder ratio controlled at 0.50. After curing for 28 days, the compressive strength of the solidified body was 1.9 MPa. Compared to Example 3, this binder had a lower proportion of water-slag powder, no desulfurized gypsum was added, resulting in insufficient gelation product formation and a lower solidified body strength than the binder system of this invention.

[0061] By comparing the above examples and comparative examples, it can be found that Examples 1-3 all use a five-component synergistic system composed of coal gangue powder, fly ash, water slag powder, desulfurized gypsum, and low-dosage cement. The 28-day compressive strengths reached 34.2 MPa, 33.7 MPa, and 34.8 MPa, respectively, all higher than 32.5 MPa, indicating that the system can still achieve good cementitious strength under low cement dosage conditions. In contrast, Comparative Example 1 did not add cement or desulfurized gypsum, and its 28-day compressive strength was only 22.5 MPa; Comparative Example 2 added a small amount of cement, but lacked desulfurized gypsum regulation, and its 28-day compressive strength was 25.8 MPa, and the strength of the filled and consolidated body was also lower than that of Example 2; Comparative Example 3 increased the cement dosage, but the proportion of water slag powder was low and no desulfurized gypsum was added, and its 28-day compressive strength was still only 28.6 MPa. The above results show that relying solely on the compounding of coal gangue powder, fly ash, and water slag powder, or simply increasing the cement content, is insufficient to achieve the bonding effect of this invention. This invention provides an early reaction basis through low-content cement, and, combined with the synergistic effect of water slag powder, fly ash, coal gangue powder, and desulfurized gypsum, can effectively improve the strength and application stability of the binder.

[0062] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention 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 the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A low-carbon, green binder, characterized in that, It includes the following components by weight: 25-45 parts coal gangue powder, 20-40 parts fly ash, 15-35 parts water slag powder, 3-12 parts desulfurized gypsum, and 5-10 parts cement.

2. The low-carbon green binder according to claim 1, characterized in that, It includes the following components by weight: 30-40 parts coal gangue powder, 25-35 parts fly ash, 18-28 parts water slag powder, 5-10 parts desulfurized gypsum, and 5-8 parts cement.

3. The low-carbon green binder according to claim 1, characterized in that, The coal gangue powder is obtained by crushing, drying, removing impurities, screening, and mechanically grinding coal gangue, and has a specific surface area of ​​350-750 m². 2 / kg.

4. The low-carbon green binder according to claim 1, characterized in that, The fly ash is Class I fly ash and / or Class II fly ash.

5. The low-carbon green binder according to claim 1, characterized in that, The water slag powder is a powder obtained by drying, grinding and screening granulated blast furnace slag, with a specific surface area of ​​400-900 m². 2 / kg.

6. The low-carbon green binder according to claim 1, characterized in that, The desulfurized gypsum is flue gas desulfurization gypsum, hemihydrate desulfurization gypsum, or desulfurized gypsum powder that has been dried and ground.

7. The low-carbon green binder according to claim 1, characterized in that, The cement is ordinary Portland cement.

8. A method for preparing a low-carbon green binder as described in any one of claims 1-7 through synergistic activation of coal-based solid waste, characterized in that, The process includes the following steps: premixing coal gangue powder, fly ash and water slag powder, then adding desulfurized gypsum and cement to mix, thus obtaining the low-carbon green binder.

9. The application of a low-carbon green binder as described in any one of claims 1-7 in mine backfilling, road base stabilization, industrial solid waste solidification, and low-carbon building material preparation.

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