Efficient carbon sequestration coal mine goaf filling material and preparation process thereof

Abstract

The invention provides an efficient carbon sequestration coal mine goaf filling material and a preparation process thereof, and belongs to the technical field of solid waste resource utilization and goaf filling governance, the preparation method comprises the following steps: drying a mineralized raw material, adding the mineralized raw material into an ammonium sulfate leaching solution, fully stirring and leaching, and then carrying out solid-liquid separation; mixing and stirring the obtained solid and water to form a turbid liquid, adding an ammonia water solution into the turbid liquid, then introducing CO2 gas into the system, stirring to carry out mineralization reaction, and carrying out solid-liquid separation on the obtained reaction liquid; fully mixing the obtained solid with the blending slag material, drying and grinding to form an active cementing material; the active cementing material is mixed with the cement and the coal-based aggregate, water is added, and the mixture is fully stirred to form the efficient carbon sequestration coal mine goaf filling material. The method is high in carbon sequestration rate, leaching of heavy metal in solid waste raw materials can be inhibited, and the prepared coal mine goaf filling material is good in strength, safe and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization and goaf filling and management, and in particular to a coal mine goaf filling material with high-efficiency carbon fixation and a preparation process thereof. Background Art

[0002] Carbon dioxide capture, utilization, and storage (CCUS) is a new technology with the potential to reduce carbon dioxide emissions on a large scale. It includes CO2 capture, utilization, and storage. This technology reduces CO2 emissions into the atmosphere, mitigating the greenhouse effect, while also enabling high-value utilization of CO2. In the building materials sector, CO2 mineralization utilizes carbonating components in building materials to absorb CO2 before and after the materials are formed, undergoing a carbonation reaction. This provides strength to the building materials and can replace traditional fired bricks, autoclaved bricks, commercial concrete, and prefabricated building components.

[0003] A Chinese patent document with publication number CN115306479A discloses a block-based CO2 storage method based on the goaf of abandoned mines. When the goaf is sealed, the area is divided. By constructing different boreholes in different areas, the gas in the fracture zone and the curved sinking zone is extracted, and the collapse zone and the fracture zone are used as the main places for CO2 storage. By injecting alkaline fly ash slurry into the fracture zone and the collapse zone, the CO2 injected into the goaf is adsorbed and solidified so that it is sealed in the fracture zone and the collapse zone, thereby realizing long-term storage of CO2 gas.

[0004] Chinese patent publication CN117229024A discloses a solid waste-based cementitious material comprising concentrated brine from mines, fly ash, desulfurized gypsum, coal gangue, mineral powder, lime, carbide slag, and a mineralization enhancer, including calcium formate, sodium lactate, and sodium hydroxide. This material can be used to fill surface subsidence in coal mine goafs.

[0005] Chinese patent document with publication number CN114673552A discloses a CO2 mineralization filling method and filling system for goaf. The filling method includes: using gelling agent, admixture, water, and fly ash as mineralizing materials for primary mineralization, mixing the primary mineralized materials with a foaming agent and a foam stabilizer for foaming and opening pores, and then stirring and mixing them evenly with filling aggregates; injecting the prepared paste into the mining working face, and when the goaf is completely filled, using the porous structure formed by the foamed paste to inject CO2 into the goaf for continuous mineralization.

[0006] However, the above and current studies on mineralization maintenance and goaf backfilling rarely use indirect mineralization methods to prepare more efficient mineralized carbon-fixing filling materials.

[0007] In addition, among the traditional filling materials used in coal mine goafs, cement, sand and gravel are commonly used. From an economic perspective, these materials are relatively expensive, especially in deep mining, where construction is complex and expensive. If solid wastes such as tailings and coal gangue are used to fill goafs, these materials do not inherently possess sufficient cementitious properties. After filling, they cannot effectively reduce the movement of the goaf roof, prevent the impact caused by the fall of the upper surrounding rock, and are not conducive to the release of deep underground pressure. In particular, when large-scale collapse occurs in coal mine goafs, it may cause surface cracking or collapse. At the same time, the heavy metals carried by these solid waste materials themselves have the risk of being released during groundwater immersion, affecting groundwater quality. Summary of the Invention

[0008] In order to solve the shortcomings of the above-mentioned existing technologies, the present invention provides a preparation process for a coal mine goaf filling material with high carbon fixation efficiency. The material has a high carbon fixation rate and can inhibit the leaching of heavy metals in solid waste raw materials. The prepared coal mine goaf filling material has good strength, is safe and environmentally friendly.

[0009] The specific technical solutions adopted are as follows: A process for preparing a high-efficiency carbon-fixing coal mine goaf filling material, comprising: (1) Dry the mineralized raw materials, add them to the ammonium sulfate leaching solution, fully stir and leach, and then perform solid-liquid separation; (2) mixing the solid obtained in step (1) with water to form a suspension, adding an ammonia solution to the suspension, then introducing CO2 gas into the system to stir and cause a mineralization reaction, and performing solid-liquid separation on the obtained reaction solution; (3) fully mixing the solid obtained in step (2) with the blended slag material, drying and grinding to form an active gelling material; (4) The active cementitious material is mixed with cement and coal-based aggregate, and water is added and stirred thoroughly to form the coal mine goaf filling material with high efficiency carbon fixation.

[0010] The method of the present invention utilizes various solid wastes, such as coal gangue and fly ash, as raw materials, achieving resource utilization and reducing waste accumulation and environmental pollution. During the preparation of the product filling material, CO2 is fixed and stored through mineralization, reducing greenhouse gas emissions. First, calcium ions and / or magnesium ions are leached from the mineralized raw materials, and then a mineralized product is prepared. This can maximize the mineralization efficiency and the utilization rate of the calcium and magnesium components in the solid waste. After the mineralized product and the blended slag are made into an active cementitious material, it is mixed with cement, coal-based aggregate, and water to obtain a highly efficient carbon-fixing coal mine goaf filling material.

[0011] The mineralized raw materials are calcium-magnesium-containing industrial solid wastes, including carbide slag, magnesium slag, steel slag or calcium-silicon slag, with a particle size of less than 200 μm.

[0012] In step (1), the concentration of the ammonium sulfate leaching solution is 1-2 mol / L, and the Ca 2+ and Mg 2+ Total moles and SO4 in ammonium sulfate 2- The molar ratio is 1:2~5.

[0013] In step (1), solid-liquid separation is performed by physical filtration.

[0014] Preferably, in order to prevent slagging on the reactor wall due to excessive reaction, the stirring rate in step (1) is 600-800 rpm.

[0015] Preferably, in step (1), in order to fully leaching and increase efficiency and improve the leaching rate, the leaching temperature is 30-40°C and the leaching time is 15-20 min.

[0016] Further preferably, during the drying process of step (1) and step (3), the drying temperature is 105°C to 110°C.

[0017] In step (2), the solid obtained in step (1) is mixed with water in a mass ratio of 1:3 to 10 and stirred to form a suspension.

[0018] Preferably, in step (2), the concentration of ammonia water is 20wt%~25wt%, and ammonia water is added to the suspension until the pH is 8~11, thereby ensuring that NH4 + The molar number of Ca 2+ and Mg 2+ The total molar ratio is 1.6~1.8:1.

[0019] Preferably, the mineralization reaction temperature is ambient temperature (20-40°C).

[0020] In step (2), the purity of CO2 gas is greater than 80%, and the flow rate is 50~100 m 3 / h, control the introduction time so that the total molar number of CO2 introduced is not less than Ca 2+ and Mg 2+ 3 to 5 times the total molar number, and the injection time can be selected from 20 to 40 min.

[0021] In step (2), the CO2 gas source can come from the flue gas CO2 of thermal power generation, the exhaust gas CO2 of petrochemical industry, the tail gas CO2 of coal chemical industry, and the carbon-containing tail gas from the industrial process of the steel, cement and other industries, and can be the tail gas or the product-grade CO2 obtained through purification treatment.

[0022] Preferably, the liquid obtained from the solid-liquid separation in step (2) is evaporated and concentrated to remove excess water therein, thereby increasing the concentration of ammonium sulfate for use in the next cycle of leaching. At the same time, the mineralization is an exothermic process that will cause some ammonia to escape. In order to reduce environmental pollution and material loss, an ammonia absorption tower is established to recover the escaped ammonia.

[0023] Optionally, the blended slag is at least two of fly ash, steel slag, and blast furnace slag, and the particle size after grinding is <50 μm, of which the mass proportion of the part with a particle size ≤20 μm is greater than 80%.

[0024] Optionally, the coal-based aggregate is at least one of coal gangue and gasified slag, the particle size of the coal gangue is less than 100 mm, and the particle size of the gasified slag is less than 5 mm.

[0025] Throughout the entire production process, the mass ratio of mineralized raw materials, blended slag, cement, and coal-based aggregate is 1:3-5:1-2:7-10. Under these ratios, the blended slag accounts for 65%-75% of the active cementitious material, and cement accounts for 5%-10% of the product, achieving excellent cost-effectiveness while ensuring the product's excellent performance.

[0026] The present invention also provides a high-efficiency carbon-fixing coal mine goaf filling material prepared by the preparation process of the high-efficiency carbon-fixing coal mine goaf filling material.

[0027] Preferably, in order to ensure that the high-efficiency carbon-fixing coal mine goaf filling material has sufficient fluidity, its water content is ≥20%, and further 20% to 30%.

[0028] This high-efficiency carbon-fixing coal mine goaf filling material has high strength, good stabilization / solidification effect on heavy metal elements in the raw materials such as Mn, Cd, As, and Pb, low environmental leaching risk, and realizes the resource utilization of industrial solid waste, which is safe and environmentally friendly.

[0029] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses the indirect mineralization of CO2 to utilize calcium and magnesium ions in solid waste, which can fully utilize its mineralization potential. The mineralization conversion rate reaches more than 80%, and the product carbon fixation rate reaches more than 30%, which is much higher than the existing carbon fixation filling materials, effectively realizing the large-scale mineralization and storage of CO2.

[0030] (2) The method of the present invention uses a variety of industrial solid wastes as raw materials, such as coal gangue from coal mines, fly ash from coal-fired power plants, blast furnace slag, and carbide slag, magnesium slag, gasification slag, steel slag, etc. from chemical waste, and combines them with cement to produce high-efficiency carbon-fixing coal mine goaf filling materials, thereby achieving low-cost resource utilization.

[0031] (3) The high-efficiency carbon-fixing coal mine goaf filling material prepared by the method of the present invention has excellent durability, can adapt to the long-term wet immersion environment of coal mines, maintain strength for a long time, and can effectively inhibit the leaching process of heavy metals contained in solid waste, thereby protecting groundwater from pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention provides a flow chart for preparing the coal mine goaf filling material with high-efficiency carbon fixation.

[0033] Figure 2 This is a statistical result chart of the carbon fixation rate and compressive strength of the coal mine goaf filling materials in Examples 1-3 and Comparative Example 1.

[0034] Figure 3 This is a graph showing the soaking performance test results of the coal mine goaf filling materials in Examples 1-3 and Comparative Example 1. DETAILED DESCRIPTION

[0035] In order to make the objects, features and advantages of the present invention more clearly understood, a detailed description is given below using specific embodiments. In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in the various embodiments of the present invention can be combined accordingly without conflicting with each other.

[0036] Example 1 The raw materials used in this embodiment are divided into three categories: industrial solid waste, and other raw materials: cement, ammonia water, and ammonium sulfate. Industrial solid waste includes primary fly ash, whose CaO content is about 25%, passing through a 2 mm sieve; original steel slag, passing through a 10 mm sieve; carbide slag with a CaO content of about 70%, passing through a 200 μm sieve; ordinary Portland cement, grade PO42.5, original coal gangue, passing through a 100 mm sieve; original gasified coarse slag, passing through a 5 mm sieve; ammonia water concentration of 25 wt%; (NH4)2SO4 solution initial concentration of 1 mol / L. Prepare according to the proportion of 100 parts of fly ash paste, 100 parts of steel slag, 50 parts of carbide slag, 100 parts of cement, 400 parts of coal gangue, and 100 parts of gasified coarse slag (by mass) per ton. The specific operations of the raw material reaction and preparation process are as follows ( Figure 1 ): (1) Dry the carbide slag in a drying chamber at 105°C for 5 h, then immerse it in a (NH4)2SO4 solution (Ca in the carbide slag is 2+ and Mg 2+ Total moles and SO4 in ammonium sulfate 2-The mixture was stirred at 40 °C for 15 min at a stirring rate of 700 rpm, and then solid-liquid separation was performed.

[0037] (2) The separated solid is sent to a CO2 mineralization tank and mixed with water at a mass ratio of 1:5 to form a suspension. Ammonia water is added to the suspension until the pH is about 8, and then CO2 (purity>99%) is continuously bubbled into the tank and stirred to cause mineralization reaction for 40 minutes (the total molar number of CO2 is not less than Ca 2+ and Mg 2+ 3 times the total number of moles), with a flow rate of 50 m 3 / h, then the solid is filtered and the liquid is evaporated and concentrated for secondary leaching.

[0038] (3) The filtered solid is mixed with fly ash and steel slag and dried and ground for 2 h. The particle size after grinding is less than 50 μm, and the mass proportion of the particle size ≤ 20 μm is greater than 80%, which is the carbon-fixing cementitious material.

[0039] (4) Cement, coal gangue, gasified coarse slag and carbon-fixing cementitious materials are mixed in a mixing tank, 250 parts of water are added, and the mixture is fully stirred to form a filling paste material, which is then pumped into the goaf through a filling pump to complete the filling.

[0040] The filling paste material was tested, and the test items included carbon fixation rate, compressive strength, and immersion performance. The carbon fixation rate was the percentage of absorbed CO2 in the solid mass obtained in step (2). The compressive strength test was carried out in accordance with the national standard "Concrete Block and Brick Test Method Coal Mine Paste Filling Mining Technical Specification" (GB / T 4111-2013). The immersion performance test was carried out after hydration for 28 days and the compressive strength test was carried out after immersion in water for different times. The test results showed that the average carbon fixation rate was 39.6%, and the compressive strength reached 6.2 MPa ( Figure 2 The immersion performance test showed that the strength increased slightly within 28 days of immersion, with no strength loss ( Figure 3 ).

[0041] Example 2 The raw materials used in this embodiment are divided into three categories: industrial solid waste, cement, ammonia water, and ammonium sulfate. Industrial solid waste includes primary fly ash with a CaO content of approximately 25% and passing through a 2 mm sieve; raw steel slag, passing through a 10 mm sieve; carbide slag with a CaO content of approximately 70% and passing through a 200 μm sieve; ordinary Portland cement, grade PO42.5, raw coal gangue, passing through a 100 mm sieve; raw gasified coarse slag, passing through a 5 mm sieve; ammonia water concentration of 25 wt%; and an initial concentration of (NH4)2SO4 solution of 1 mol / L. The ingredients are prepared in the following proportions (by mass) per ton of paste fly ash: 100 parts of steel slag, 50 parts of carbide slag, 100 parts of cement, 400 parts of coal gangue, and 100 parts of gasified coarse slag. The specific operations of the raw material reaction and preparation process are as follows: (1) Dry the carbide slag in a drying chamber at 105°C for 5 h, then immerse it in a (NH4)2SO4 solution (Ca in the carbide slag is 2+ and Mg 2+ Total moles and SO4 in ammonium sulfate 2- The mixture was stirred at 40 °C for 15 min at a stirring rate of 700 rpm, and then solid-liquid separation was performed.

[0042] (2) The separated solid is sent to a CO2 mineralization tank and mixed with water at a mass ratio of 1:8 to form a suspension. Ammonia water is added to the suspension until the pH is about 8, and then CO2 (purity>99%) is continuously bubbled into the tank and stirred to cause mineralization reaction for 20 minutes (the total molar number of CO2 is not less than Ca 2+ and Mg 2+ 3 times the total number of moles), with a flow rate of 100 m 3 / h, then the solid is filtered and the liquid is evaporated and concentrated for secondary leaching.

[0043] (3) The filtered solid is mixed with fly ash and steel slag and dried and ground for 2 h. The particle size after grinding is less than 50 μm, and the mass proportion of the particle size ≤ 20 μm is greater than 80%, which is the carbon-fixing cementitious material.

[0044] (4) Cement, coal gangue, gasified coarse slag and carbon-fixing cementitious materials are mixed in a mixing tank, 250 parts of water are added, and the mixture is fully stirred to form a filling paste material, which is then pumped into the goaf through a filling pump to complete the filling.

[0045] The filling paste material was tested using the same test items and methods as in Example 1. The test results showed that the average carbon fixation rate was 32.3%. The compressive strength reached 5.3 MPa ( Figure 2 ), the immersion performance test showed that the strength loss within 28 days of immersion was less than 5% ( Figure 3 ).

[0046] Example 3 The raw materials used in this embodiment are divided into three categories: industrial solid waste, cement, ammonia water, and ammonium sulfate. Industrial solid waste includes primary fly ash with a CaO content of approximately 25% and passing through a 2 mm sieve; raw steel slag, passing through a 10 mm sieve; carbide slag with a CaO content of approximately 70% and passing through a 200 μm sieve; ordinary Portland cement, grade PO42.5, raw coal gangue, passing through a 100 mm sieve; raw gasified coarse slag, passing through a 5 mm sieve; ammonia water with a mass fraction of 25 wt%; and an initial concentration of (NH4)2SO4 solution of 1 mol / L. The raw materials are prepared in the following proportions (by mass) per ton of fly ash paste: 120 parts, 100 parts, 60 parts, 70 parts, 400 parts, and 100 parts (by mass) of steel slag, carbide slag, cement, and gangue. The specific operations of the raw material reaction and preparation process are as follows: (1) Dry the carbide slag in a drying chamber at 105°C for 5 h, then immerse it in a (NH4)2SO4 solution (Ca in the carbide slag is 2+ and Mg 2+ Total moles and SO4 in ammonium sulfate 2- The mixture was stirred at 40 °C for 15 min at a stirring rate of 700 rpm, and then solid-liquid separation was performed.

[0047] (2) The separated solid is sent to a CO2 mineralization tank and mixed with water at a mass ratio of 1:10 to form a suspension. Ammonia water is added to the suspension until the pH is about 11, and then CO2 (purity>99%) is continuously bubbled into the tank and stirred to cause mineralization reaction for 40 minutes (the total molar number of CO2 is not less than Ca 2+ and Mg 2+ 5 times the total number of moles), with a flow rate of 50 m 3 / h, then the solid is filtered and the liquid is evaporated and concentrated for secondary leaching.

[0048] (3) The filtered solid is mixed with fly ash and steel slag and dried and ground for 2 h. The particle size after grinding is less than 50 μm, and the mass proportion of the particle size ≤ 20 μm is greater than 80%, which is the carbon-fixing cementitious material.

[0049] (4) Cement, coal gangue, gasified coarse slag and carbon-fixing cementitious materials are mixed in a mixing tank, 250 parts of water are added, and the mixture is fully stirred to form a filling paste material, which is then pumped into the goaf through a filling pump to complete the filling.

[0050] The filling paste material was tested. The test items and test methods were the same as those in Example 1. The test results showed that the average carbon fixation rate was 39.1%, and the compressive strength reached 4.1 MPa at 28 days of age. Figure 2 The immersion performance test showed that the strength loss within 28 days of immersion was less than 5% ( Figure 3 ).

[0051] Comparative Example 1 The raw materials used in this comparative example are divided into three categories: industrial solid waste, cement, ammonia water, and ammonium sulfate. Industrial solid waste includes primary fly ash with a CaO content of approximately 25%, which passes through a 2 mm sieve; original steel slag, which passes through a 10 mm sieve; carbide slag with a CaO content of approximately 70%, which passes through a 200 μm sieve; ordinary Portland cement, grade PO42.5, original coal gangue, which passes through a 100 mm sieve; original gasification coarse slag, which passes through a 5 mm sieve; ammonia water concentration of 25 wt%; and an initial concentration of (NH4)2SO4 solution of 1 mol / L. The preparation ratio is 120 parts by mass per ton of fly ash paste, 100 parts by mass of steel slag, 60 parts by mass of carbide slag, 70 parts by mass of cement, 400 parts by mass of coal gangue, and 100 parts by mass of gasification coarse slag. The specific operations of the raw material reaction and preparation process are as follows: (1) Dry the carbide slag in a drying chamber at 105°C for 5 h, then immerse it in a (NH4)2SO4 solution (Ca in the carbide slag is 2+ and Mg 2+ Total moles and SO4 in ammonium sulfate 2- The mixture was stirred at 40 °C for 15 min at a stirring rate of 700 rpm, and then solid-liquid separation was performed.

[0052] (2) The separated solid is sent to a CO2 mineralization tank and mixed with water at a mass ratio of 1:3 to form a suspension. Ammonia water is added to the suspension until the pH is about 11, and then CO2 (purity of about 50%) is continuously bubbled into the tank and stirred to cause a mineralization reaction for 40 minutes (the total molar number of CO2 is not less than Ca 2+ and Mg 2+ 2 times the total number of moles, but not 3 times), with a flow rate of 50 m 3 / h, then the solid is filtered and the liquid is evaporated and concentrated for secondary leaching.

[0053] (3) The filtered solid is mixed with fly ash and steel slag and dried and ground for 2 h. The particle size after grinding is less than 50 μm, and the mass proportion of the particle size ≤ 20 μm is greater than 80%, which is the carbon-fixing cementitious material.

[0054] (4) Cement, coal gangue, gasified coarse slag and carbon-fixing cementitious materials are mixed in a mixing tank, 250 parts of water are added, and the mixture is fully stirred to form a filling paste material, which is then pumped into the goaf through a filling pump to complete the filling.

[0055] The filling paste material obtained in this comparative example was tested. The test items and test methods were the same as those in Example 1. The test results showed that the average carbon fixation rate was 21.8%, and the compressive strength reached 3.2 MPa ( Figure 2 The immersion performance test showed that the strength loss within 28 days of immersion was less than 10% ( Figure 3 ).

[0056] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A process for preparing a high-efficiency carbon-fixing coal mine goaf filling material, characterized in that: include: (1) Dry the mineralized raw materials, add them to the ammonium sulfate leaching solution, fully stir and leach, and then perform solid-liquid separation; (2) mixing the solid obtained in step (1) with water to form a suspension, adding an ammonia solution to the suspension, then introducing CO2 gas into the system to stir and cause a mineralization reaction, and performing solid-liquid separation on the obtained reaction solution; (3) fully mixing the solid obtained in step (2) with the blended slag material, drying and grinding to form an active gelling material; (4) The active cementitious material is mixed with cement and coal-based aggregate, and water is added and stirred thoroughly to form the coal mine goaf filling material with high efficiency carbon fixation.

2. The process for preparing the high-efficiency carbon-fixing coal mine goaf filling material according to claim 1, characterized in that: The mineralized raw materials are calcium-magnesium-containing industrial solid wastes, including carbide slag, magnesium slag, steel slag or calcium-silicon slag, with a particle size of less than 200 μm.

3. The process for preparing the high-efficiency carbon-fixing coal mine goaf filling material according to claim 1, characterized in that: The concentration of the ammonium sulfate leaching solution is 1~2 mol / L, and the Ca 2+ and Mg 2+ Total moles and SO4 in ammonium sulfate 2- The molar ratio is 1:2~5.

4. The process for preparing the high-efficiency carbon-fixing coal mine goaf filling material according to claim 1, characterized in that: In step (1), the leaching temperature is 30-40°C, and the leaching time is 15-20 min.

5. The process for preparing the high-efficiency carbon-fixing coal mine goaf filling material according to claim 1, characterized in that: In step (2), the concentration of ammonia water is 20 wt% to 25 wt%, and the ammonia water solution is added to the suspension until the pH is 8 to 11.

6. The process for preparing the high-efficiency carbon-fixing coal mine goaf filling material according to claim 1, characterized in that: In step (2), the purity of CO2 gas is greater than 80%, and the flow rate is 50~100 m 3 / h, control the introduction time so that the total molar number of CO2 introduced is not less than Ca 2+ and Mg 2+ 3 times the total number of moles.

7. The process for preparing a high-efficiency carbon-fixing coal mine goaf filling material according to claim 1, characterized in that: The blended slag is at least two of fly ash, steel slag, and blast furnace slag, and the particle size after grinding is <50 μm, of which the mass proportion of the part with a particle size ≤20 μm is greater than 80%.

8. The process for preparing a high-efficiency carbon-fixing coal mine goaf filling material according to claim 1, characterized in that: The coal-based aggregate is at least one of coal gangue and fumed slag, the particle size of the coal gangue is less than 100 mm, and the particle size of the fumed slag is less than 5 mm.

9. The process for preparing a high-efficiency carbon-fixing coal mine goaf filling material according to claim 1, characterized in that: During the whole preparation process, the mass ratio of mineralized raw materials, blended slag, cement and coal-based aggregate is 1:3~5:1~2:7~10.

10. The high-efficiency carbon-fixing coal mine goaf filling material prepared by the preparation process of the high-efficiency carbon-fixing coal mine goaf filling material according to any one of claims 1 to 9, characterized in that: Moisture content ≥20%.

Images