Steel slag-based rapid carbon sequestration filling material, preparation method and application thereof

Abstract

The application discloses a kind of steel slag-based fast carbon sequestration type filling material and preparation method thereof, it is related to carbon sequestration type filling material field, filling material includes: aggregate, cementing material, complex chelating agent and water;Wherein, the complex chelating agent is ethylenediamine tetraacetic acid, triethanolamine, citric acid mixture.Preparation method is: steel slag, water, complex chelating agent are mixed in proportion stirring, under the action of ultrasonic wave and activated;Into the material after stirring, carry out first step mineralization;The obtained material is stirred evenly with fly ash, cement, aggregate in turn, and obtain filling slurry;Slurry is transported to mined-out area by filling pump, and forms filling body;Into the filling area, realize the second step of solid storage.The application can effectively solve the problem of large solid waste stock, realize long-term storage by mineralization reaction of filling material, the carbon sequestration amount and strength performance of filling material prepared by the application are excellent, and have good ecological benefits and popularization value.

Description

Technical Field

[0001] This invention relates to the field of carbon-fixing backfill materials, and more particularly to a steel slag-based rapid carbon-fixing backfill material, its preparation method, and its application. Background Technology

[0002] Coal mining processes create numerous goaf areas, which not only pose risks such as spontaneous combustion of residual coal and water accumulation, but also cause surface subsidence and aquifer damage. Cemented backfilling mining technology uses cement and other cementing materials to mix fly ash, coal gangue, and other coal-based solid waste to prepare backfill material for refilling goaf areas, thereby controlling surface subsidence and disposing of solid waste. Simultaneously, the large amounts of pollutants emitted during coal production and utilization... This has become an urgent problem that needs to be solved. Capture, utilization, and storage (CFS) technologies can effectively alleviate carbon emission pressures, among which mineralization storage can utilize cemented backfill as a means of containment. Absorbing carrier, to achieve Long-term geological preservation.

[0003] Furthermore, the large-scale discharge of steel slag has caused serious pollution to the soil and air. It is worth noting that steel slag contains... , , It contains mineral phases, similar in composition to cement clinker, and possesses potential cementitious activity. Ethylenediaminetetraacetic acid (EDTA), as a chelating agent, can promote the leaching of calcium and magnesium ions from steel slag, thereby improving carbonation efficiency.

[0004] However, there is currently little research on the use of ethylenediaminetetraacetic acid, triethanolamine, and citric acid to activate steel slag in the preparation of filling materials to replace part of the cement, which leads to uncertainty in its application in mine filling projects. To address this, this invention adds steel slag to gangue-based filling materials to replace part of the cement, and adds ethylenediaminetetraacetic acid, triethanolamine, and citric acid for chelation to improve the strength and carbon fixation performance of the filling materials. Summary of the Invention

[0005] This solution addresses the problems and needs raised above by proposing a rapid carbonization backfill material based on steel slag and its preparation method. The above technical objectives can be achieved by adopting the following technical features, and it also brings about several other technical effects.

[0006] One objective of this invention is to provide a steel slag-based rapid carbonization backfill material, comprising: aggregate, cementitious material, composite chelating agent, and water, wherein the mass ratio of each component is: aggregate: 45-55%; cementitious material: 30-70%; chelating agent: 0-0.1%; water-cement ratio: 0.5; wherein the cementitious material is a mixture of fly ash, cement, and steel slag; and the composite chelating agent is a mixture of ethylenediaminetetraacetic acid, triethanolamine, and citric acid, wherein the mass ratio of the three chelating agents is: ethylenediaminetetraacetic acid: 30-50%; triethanolamine: 20-40%; citric acid: 10-30%.

[0007] In addition, the steel slag-based rapid carbonization backfill material and its preparation method according to the present invention may also have the following technical features: In one example of the present invention, the aggregate is gangue of all particle sizes, including: fine aggregate, medium aggregate and coarse aggregate, wherein gangue particles with a particle size of 0mm-2mm are fine aggregate, gangue particles with a particle size of 2mm-5mm are medium aggregate, and gangue particles with a particle size of 5mm-10mm are coarse aggregate.

[0008] In one example of the present invention, the mass ratio of fine aggregate, medium aggregate, and coarse aggregate is 1:1:1.

[0009] In one example of the present invention, the mass ratio of each component in the cementitious material is: fly ash: 25-35%; cement: 5-20%; steel slag: 0-15%.

[0010] In one example of the present invention, the median particle size of the fly ash in the cementitious material is 8-12 mm. The median particle size of the cement is 10-14. The median particle size of the steel slag is 65-75 mm. .

[0011] Another object of the present invention is to provide a method for preparing a steel slag-based rapid carbonization backfill material as described above, comprising the following steps: Step S10: Steel slag, water, ethylenediaminetetraacetic acid, triethanolamine, and citric acid are mixed and stirred in proportion, and pre-dispersed and chemically activated under ultrasonic action to form a mixed material; Step S20: Introduce into the mixture Simultaneously, the mixed materials are subjected to ultrasonic strengthening treatment for the first step of efficient mineralization; Step S30: Mix the material obtained from the first step of mineralization with fly ash and cement in proportion and stir evenly for 4-5 minutes. Then add aggregate and continue stirring for 2-3 minutes to obtain filling slurry. Step S40: The filling slurry is transported to the goaf by the filling pump to form a steel slag-based rapid carbonization type filling body; Step S50: After the specified time, gas is introduced into the filling area of ​​the pre-embedded gas injection pipeline. To perform sealing and storage, thereby achieving [the following] The second step is to solidify.

[0012] In one example of the present invention, in step S10, the mixing time is 12-24 hours, the stirring speed is 500-1000 r / min, the ultrasonic frequency is 20-40 kHz, and the ultrasonic treatment time is 10-20 min.

[0013] In one example of the present invention, in step S20, the mineralization condition is that the solution is introduced from the bottom of the stirring tank. The purity of carbon dioxide gas is not less than 99.9%, the temperature is 40-60℃, the pressure is 1-5MPa, the mineralization time is 20-40min, and the stirring speed is 500-1000r / min.

[0014] In one example of the present invention, in step S50, gas is introduced into the filling area of ​​the pre-embedded gas injection pipeline. The method is as follows: the injection pressure is 2-4 MPa, the flow rate is 5-10 t / h, and the injection time is 4-5 h.

[0015] Another objective of this invention is to propose the application of a steel slag-based rapid carbonization type filling material as described above in the filling of goaf areas in coal mines.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention independently developed a high-performance composite chelating agent, which is made of ethylenediaminetetraacetic acid, triethanolamine and citric acid. Combined with ultrasonic-assisted activation and first-stage high-efficiency mineralization, the strong chelating effect of the composite chelating agent and the ultrasonic action significantly improve the performance of steel slag. Leaching rate and The reaction kinetics effectively improved the overall carbon fixation capacity of the filling material.

[0017] (2) The composite chelating agent also accelerates the early hydration of cement and steel slag. At the same time, mineral products such as carbonate crystals fill the material pores, making the material structure more compact and greatly improving the uniaxial compressive strength of the filling material to meet the downhole filling requirements.

[0018] (3) The present invention adopts a two-stage step mineralization, and by controlling the stirring speed, vibration amplitude, temperature and pressure in the first stage of mineralization, it achieves fine control of the carbonization reaction process and improves the carbonization efficiency of the steel slag-based rapid carbonization backfill material.

[0019] (4) This invention uses solid waste such as gangue, fly ash, and steel slag as raw materials to realize the resource utilization of solid waste, which has good ecological benefits and promotion value.

[0020] The preferred embodiments of the invention will be described in more detail below with reference to the accompanying drawings, so as to facilitate an understanding of the features and advantages of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. The drawings are merely illustrative of some embodiments of the present invention and are not intended to limit the scope of the present invention to all embodiments.

[0022] Figure 1 The compressive strength diagrams at various ages of Examples 1-5 of the steel slag-based rapid carbonization backfill material according to the present invention are shown. Figure 2 The graph shows the carbon fixation amount at different ages for Examples 1-5 of the steel slag-based rapid carbon fixation backfill material according to the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The same reference numerals in the drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, “an” or “a” and similar terms do not necessarily indicate a quantity limitation. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0025] According to a first aspect of the present invention, a steel slag-based rapid carbonization backfill material comprises: aggregate, cementitious material, composite chelating agent, and water, wherein the mass ratio of each component is: aggregate: 45-55%; cementitious material: 30-70%; chelating agent: 0-0.1%; water-cement ratio: 0.5; wherein the cementitious material is a mixture of fly ash, cement, and steel slag; and the composite chelating agent is a mixture of ethylenediaminetetraacetic acid, triethanolamine, and citric acid, wherein the mass ratio of the three chelating agents is: ethylenediaminetetraacetic acid: 30-50%; triethanolamine: 20-40%; citric acid: 10-30%.

[0026] The filling material utilizes a high-performance composite chelating agent independently developed from ethylenediaminetetraacetic acid, triethanolamine, and citric acid. Combined with ultrasonic-assisted activation and a first-stage high-efficiency mineralization process, the strong chelating effect of the composite chelating agent and ultrasonic action significantly improve the mineralization of steel slag. Leaching rate and The reaction kinetics effectively improved the overall carbon fixation capacity of the filling material.

[0027] The composite chelating agent in this filling material also accelerates the early hydration of cement and steel slag. At the same time, mineral products such as carbonate crystals fill the material pores, making the material structure more compact and significantly improving the uniaxial compressive strength of the filling material, thus meeting the requirements for downhole filling.

[0028] The filling material adopts a two-stage step mineralization process. By controlling the stirring speed, vibration amplitude, temperature and pressure in the first stage of mineralization, the carbonization reaction process is precisely controlled, and the carbon fixation efficiency of the steel slag-based rapid carbon fixation filling material is improved.

[0029] This filling material uses solid waste such as gangue, fly ash, and steel slag as raw materials, realizing the resource utilization of solid waste and having good ecological benefits and promotion value.

[0030] In one example of the present invention, the aggregate is gangue of all particle sizes, including: fine aggregate, medium aggregate and coarse aggregate, wherein gangue particles with a particle size of 0mm-2mm are fine aggregate, gangue particles with a particle size of 2mm-5mm are medium aggregate, and gangue particles with a particle size of 5mm-10mm are coarse aggregate.

[0031] In one example of the present invention, the mass ratio of fine aggregate, medium aggregate, and coarse aggregate is 1:1:1.

[0032] In one example of the present invention, the mass ratio of each component in the cementitious material is: fly ash: 25-35%; cement: 5-20%; steel slag: 0-15%.

[0033] In one example of the present invention, the median particle size of the fly ash in the cementitious material is 8-12 mm. The median particle size of the cement is 10-14. The median particle size of the steel slag is 65-75 mm. .

[0034] According to a second aspect of the present invention, a method for preparing a steel slag-based rapid carbonization backfill material as described above includes the following steps: Step S10: Steel slag, water, ethylenediaminetetraacetic acid, triethanolamine, and citric acid are mixed and stirred in proportion, and pre-dispersed and chemically activated under ultrasonic action to form a mixed material; Step S20: Introduce into the mixture Simultaneously, the mixed materials are subjected to ultrasonic strengthening treatment for the first step of efficient mineralization; Step S30: Mix the material obtained from the first step of mineralization with fly ash and cement in proportion and stir evenly for 4-5 minutes. Then add aggregate and continue stirring for 2-3 minutes to obtain filling slurry. Step S40: The filling slurry is transported to the goaf by the filling pump to form a steel slag-based rapid carbonization type filling body; Step S50: After a specified time (e.g., 1 day), gas is introduced into the filling area of ​​the pre-buried gas injection pipeline. To perform sealing and storage, thereby achieving [the following] The second step is to solidify.

[0035] This preparation method independently developed a high-performance composite chelating agent, which is composed of ethylenediaminetetraacetic acid, triethanolamine, and citric acid. Combined with ultrasonic-assisted activation and a first-stage high-efficiency mineralization, the strong chelating effect of the composite chelating agent and ultrasonic action significantly improve the performance of steel slag. Leaching rate and The reaction kinetics effectively improved the overall carbon fixation capacity of the filling material.

[0036] The composite chelating agent in this preparation method also accelerates the early hydration of cement and steel slag. At the same time, mineral products such as carbonate crystals fill the material pores, making the material structure more compact and significantly improving the uniaxial compressive strength of the filling material, thus meeting the requirements for downhole filling.

[0037] The preparation method adopts a two-stage stepwise mineralization process. By controlling the stirring speed, vibration amplitude, temperature and pressure in the first stage of mineralization, the carbonization reaction process can be precisely controlled, and the carbon fixation efficiency of the steel slag-based rapid carbon fixation backfill material can be improved.

[0038] This preparation method uses solid waste such as gangue, fly ash, and steel slag as raw materials, realizing the resource utilization of solid waste and having good ecological benefits and promotion value.

[0039] In one example of the present invention, in step S10, the mixing time is 12-24 hours, the stirring speed is 500-1000 r / min, the ultrasonic frequency is 20-40 kHz, and the ultrasonic treatment time is 10-20 min.

[0040] In one example of the present invention, in step S20, the mineralization condition is that the solution is introduced from the bottom of the stirring tank. The purity of carbon dioxide gas is not less than 99.9%, the temperature is 40-60℃, the pressure is 1-5MPa, the mineralization time is 20-40min, and the stirring speed is 500-1000r / min.

[0041] In one example of the present invention, in step S50, gas is introduced into the filling area of ​​the pre-embedded gas injection pipeline. The method is as follows: the injection pressure is 2-4 MPa, the flow rate is 5-10 t / h, and the injection time is 4-5 h.

[0042] The application of a steel slag-based rapid carbonization type filling material as described above in the filling of goaf areas in underground coal mines, according to a third aspect of the present invention.

[0043] Specific examples: In the following examples and comparative examples, the water-cement ratio is fixed at 0.5, that is, water: cement, fly ash, steel slag, ethylenediaminetetraacetic acid, triethanolamine, citric acid = 1:2. Example 1:

[0044] A steel slag-based rapid carbon fixation backfill material and its preparation method are disclosed below: S10: Weigh the raw materials according to the following mass ratio: 45% gangue of three particle sizes, 35% fly ash, 9% cement, 10% steel slag, 0.4% ethylenediaminetetraacetic acid (EDTA), 0.3% triethanolamine, and 0.3% citric acid. Mix the steel slag, water, EDTA, triethanolamine, and citric acid according to the ratio, and stir at 500-1000 r / min for 12-24 hours. The chelation effect of EDTA, triethanolamine, and citric acid promotes the mixing of these components. , The leaching process was followed by pre-dispersion and chemical activation under ultrasonic treatment. The ultrasonic frequency was 20-40kHz, and the ultrasonic treatment time was 10-20min. S20: Passing the material stirred in step S10 into the mixing drum from the bottom. The temperature is 40-60℃, the pressure is 1-5MPa, the mineralization time is 20-40min, the stirring speed is 500-1000r / min, and ultrasonic waves are introduced to strengthen the material. Evenly dispersed, it undergoes the first step of efficient mineralization; S30: Mix the material obtained from the first mineralization step of S20 with fly ash and cement in proportion and stir evenly for 4-5 minutes. Then add aggregate and continue stirring for 2-3 minutes to obtain filling slurry. S40: Pour the uniformly mixed filling slurry from step S30 into a 50mm×100mm mold, place it at room temperature for 1 day, then demold it and place it in a curing chamber at a temperature of 20±2℃ and a relative humidity of 95% to obtain the filling body. S50: Samples cured for 3 days, 7 days, 14 days, and 28 days were placed into the reactor, and the gas was introduced... The sample underwent a 4-hour sealing process, with a confining pressure and axial pressure of 2 MPa applied to the sample, and the temperature maintained at 25°C to achieve [the desired effect]. The second step was carbon sequestration, and the compressive strength and carbon sequestration amount of the samples were tested after carbon sequestration at curing ages of 3 days, 7 days, 14 days, and 28 days. The results are shown in Table 1. Table 1 Example 2:

[0045] A steel slag-based rapid carbon fixation backfill material and its preparation method are disclosed below: S10: Weigh the raw materials according to the following mass ratio: 55% gangue of three particle sizes, 25% fly ash, 9% cement, 10% steel slag, 0.4% ethylenediaminetetraacetic acid (EDTA), 0.3% triethanolamine, and 0.3% citric acid. Mix the steel slag, water, EDTA, triethanolamine, and citric acid according to the ratio, and stir at 500-1000 r / min for 12-24 hours. The chelation effect of EDTA, triethanolamine, and citric acid promotes the mixing of these components. , The leaching process was followed by pre-dispersion and chemical activation under ultrasonic treatment. The ultrasonic frequency was 20-40kHz, and the ultrasonic treatment time was 10-20min. S20: Introduce the material stirred in step S20 from the bottom of the mixing drum. The temperature is 40-60℃, the pressure is 1-5MPa, the mineralization time is 20-40min, the stirring speed is 500-1000r / min, and ultrasonic waves are introduced to strengthen the material. Evenly dispersed, it undergoes the first step of efficient mineralization; S30: Mix the material obtained from the first mineralization step of S20 with fly ash and cement in proportion and stir evenly for 4-5 minutes. Then add aggregate and continue stirring for 2-3 minutes to obtain filling slurry. S40: Pour the uniformly mixed filling slurry from step S30 into a 50mm×100mm mold, place it at room temperature for 1 day, then demold it and place it in a curing chamber at a temperature of 20±2℃ and a relative humidity of 95% to obtain the filling body. S50: Samples cured for 3 days, 7 days, 14 days, and 28 days were placed into the reactor, and the gas was introduced... The sample underwent a 4-hour sealing process, with a confining pressure and axial pressure of 2 MPa applied to the sample, and the temperature maintained at 25°C to achieve [the desired effect]. The second step was carbon sequestration, and the compressive strength and carbon sequestration amount of the samples were tested after carbon sequestration at curing ages of 3 days, 7 days, 14 days, and 28 days. The results are shown in Table 2. Table 2 Example 3:

[0046] A steel slag-based rapid carbon fixation backfill material and its preparation method are disclosed below: S10: Weigh the raw materials according to the following mass ratio: 50% gangue of three particle sizes, 35% fly ash, 14% cement, 0.4% ethylenediaminetetraacetic acid (EDTA), 0.3% triethanolamine, and 0.3% citric acid. Mix the steel slag, water, EDTA, triethanolamine, and citric acid according to the ratio, and stir at 500-1000 r / min for 12-24 hours. The chelation effect of EDTA, triethanolamine, and citric acid promotes the growth of the mixture. , The leaching process was followed by pre-dispersion and chemical activation under ultrasonic treatment. The ultrasonic frequency was 20-40kHz, and the ultrasonic treatment time was 10-20min. S20: Introduce the material stirred in step S20 from the bottom of the mixing drum. The temperature is 40-60℃, the pressure is 1-5MPa, the mineralization time is 20-40min, the stirring speed is 500-1000r / min, and ultrasonic waves are introduced to strengthen the material. Evenly dispersed, it undergoes the first step of efficient mineralization; S30: Mix the material obtained from the first mineralization step of S20 with fly ash and cement in proportion and stir evenly for 4-5 minutes. Then add aggregate and continue stirring for 2-3 minutes to obtain filling slurry. S40: Pour the uniformly mixed filling slurry from step S30 into a 50mm×100mm mold, place it at room temperature for 1 day, then demold it and place it in a curing chamber at a temperature of 20±2℃ and a relative humidity of 95% to obtain the filling body. S50: Samples cured for 3 days, 7 days, 14 days, and 28 days were placed into the reactor, and the gas was introduced... The sample underwent a 4-hour sealing process, with a confining pressure and axial pressure of 2 MPa applied to the sample, and the temperature maintained at 25°C to achieve [the desired effect]. The second step was carbon sequestration, and the compressive strength and carbon sequestration amount of the samples were tested after carbon sequestration at curing ages of 3 days, 7 days, 14 days, and 28 days. The results are shown in Table 3. Table 3 Example 4:

[0047] A steel slag-based rapid carbon fixation backfill material and its preparation method are disclosed below: S10: Weigh the raw materials according to the following mass ratio: 50% gangue of three particle sizes, 25% fly ash, 9% cement, 15% steel slag, 0.4% ethylenediaminetetraacetic acid (EDTA), 0.3% triethanolamine, and 0.3% citric acid. Mix the steel slag, water, EDTA, triethanolamine, and citric acid according to the ratio, and stir at 500-1000 r / min for 12-24 hours. The chelation effect of EDTA, triethanolamine, and citric acid promotes the mixing of these components. , The leaching process was followed by pre-dispersion and chemical activation under ultrasonic treatment. The ultrasonic frequency was 20-40kHz, and the ultrasonic treatment time was 10-20min. S20: Introduce the material stirred in step S20 from the bottom of the mixing drum. The temperature is 40-60℃, the pressure is 1-5MPa, the mineralization time is 20-40min, the stirring speed is 500-1000r / min, and ultrasonic waves are introduced to strengthen the material. Evenly dispersed, it undergoes the first step of efficient mineralization; S30: Mix the material obtained from the first mineralization step of S20 with fly ash and cement in proportion and stir evenly for 4-5 minutes. Then add aggregate and continue stirring for 2-3 minutes to obtain filling slurry. S40: Pour the uniformly mixed filling slurry from step S30 into a 50mm×100mm mold, place it at room temperature for 1 day, then demold it and place it in a curing chamber at a temperature of 20±2℃ and a relative humidity of 95% to obtain the filling body. S50: Samples cured for 3 days, 7 days, 14 days, and 28 days were placed into the reactor, and the gas was introduced... The sample underwent a 4-hour sealing process, with a confining pressure and axial pressure of 2 MPa applied to the sample, and the temperature maintained at 25°C to achieve [the desired effect]. The second step was carbon sequestration, and the compressive strength and carbon sequestration amount of the samples were tested after carbon sequestration at curing ages of 3 days, 7 days, 14 days, and 28 days. The results are shown in Table 4. Table 4 Example 5:

[0048] A steel slag-based rapid carbon fixation backfill material and its preparation method are disclosed below: S10. Weigh the raw materials according to the following mass ratio: 50% gangue of three particle sizes, 25% fly ash, 10% cement, and 15% steel slag; mix the steel slag, water, ethylenediaminetetraacetic acid, triethanolamine, and citric acid in the specified proportions, and stir at 500-1000 r / min for 12-24 hours. The chelation effect of ethylenediaminetetraacetic acid, triethanolamine, and citric acid promotes the mixing process. , The leaching process was followed by pre-dispersion and chemical activation under ultrasonic treatment. The ultrasonic frequency was 20-40kHz, and the ultrasonic treatment time was 10-20min. S20. Pass the material stirred in step S20 into the mixing drum from the bottom. The temperature is 40-60℃, the pressure is 1-5MPa, the mineralization time is 20-40min, the stirring speed is 500-1000r / min, and ultrasonic waves are introduced to strengthen the material. Evenly dispersed, it undergoes the first step of efficient mineralization; S30. The material obtained from the first mineralization step in step S20 is first mixed with fly ash and cement in proportion and stirred evenly for 4-5 minutes. Then, aggregate is added and stirring is continued for 2-3 minutes to obtain filling slurry. S40. Pour the uniformly mixed filling slurry from step S30 into a 50mm×100mm mold, place it at room temperature for 1 day, then demold it and place it in a curing chamber at a temperature of 20±2℃ and a relative humidity of 95% to obtain the filling body. S50, samples cured for 3 days, 7 days, 14 days, and 28 days were placed into the reactor, and air was introduced. The sample underwent a 4-hour sealing process, with a confining pressure and axial pressure of 2 MPa applied to the sample, and the temperature maintained at 25°C to achieve [the desired effect]. The second step was carbon sequestration, and the compressive strength and carbon sequestration amount of the samples were tested after carbon sequestration at curing ages of 3 days, 7 days, 14 days, and 28 days. The results are shown in Table 5. Table 5 The steel slag-based rapid carbon-fixing backfill material of the present invention has high performance, specifically in terms of high uniaxial compressive strength and large carbon fixation capacity, and realizes the efficient utilization of various industrial solid wastes, solving the environmental problems caused by large-scale stockpiling.

[0049] Combined with appendix Figure 1 and Figure 2Results showed that the compressive strength and carbon fixation performance of the filling material were significantly improved after the addition of the composite chelating agent. The compressive strength gradually increased with the increase of the curing age. The carbon fixation of the filling material reached its maximum at a curing age of 7 days. As the curing age continued to extend, the carbon fixation began to decrease, which is mainly related to the evolution of the pore structure of the filling material.

[0050] The foregoing description, with reference to preferred embodiments, details an exemplary embodiment of the steel slag-based rapid carbonization backfill material and its preparation method proposed in this invention. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the concept of this invention, and various combinations can be made to the various technical features and structures proposed in this invention without exceeding the protection scope of this invention, which is determined by the appended claims.

Claims

1. A steel slag-based rapid carbonization type backfill material, characterized in that, include: The mass ratio of aggregates, cementitious materials, composite chelating agents, and water is as follows: Aggregates: 45-55%; Cementitious materials: 30-70%; Chelating agent: 0-0.1%; Water-cement ratio: 0.5; wherein the cementing material is a mixture of fly ash, cement and steel slag; the composite chelating agent is a mixture of ethylenediaminetetraacetic acid, triethanolamine and citric acid, wherein the mass ratio of the three chelating agents is: ethylenediaminetetraacetic acid: 30-50%; triethanolamine: 20-40%; citric acid: 10-30%.

2. The steel slag-based rapid carbonization backfill material according to claim 1, characterized in that, The aggregates used are gangue of all particle sizes, including: fine aggregate, medium aggregate and coarse aggregate. Among them, gangue particles with a particle size of 0mm-2mm are fine aggregate, gangue particles with a particle size of 2mm-5mm are medium aggregate, and gangue particles with a particle size of 5mm-10mm are coarse aggregate.

3. The steel slag-based rapid carbonization backfill material according to claim 2, characterized in that, The mass ratio of fine aggregate, medium aggregate, and coarse aggregate is 1:1:

1.

4. The steel slag-based rapid carbonization backfill material according to claim 1, characterized in that, In the cementitious material, the mass ratio of each component is: fly ash: 25-35%; Cement: 5-20%; Steel slag: 0-15%.

5. The steel slag-based rapid carbonization backfill material according to claim 1, characterized in that, In the cementitious material: the median particle size of fly ash is 8-12. The median particle size of the cement is 10-14. The median particle size of the steel slag is 65-75 mm. .

6. A method for preparing a steel slag-based rapid carbonization backfill material as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step S10: Steel slag, water, ethylenediaminetetraacetic acid, triethanolamine, and citric acid are mixed and stirred in proportion, and pre-dispersed and chemically activated under ultrasonic action to form a mixed material; Step S20: Introduce into the mixture Simultaneously, the mixed materials are subjected to ultrasonic strengthening treatment for the first step of efficient mineralization; Step S30: Mix the material obtained from the first step of mineralization with fly ash and cement in proportion and stir evenly for 4-5 minutes. Then add aggregate and continue stirring for 2-3 minutes to obtain filling slurry. Step S40: The filling slurry is transported to the goaf by the filling pump to form a steel slag-based rapid carbonization type filling body; Step S50: After the specified time, gas is introduced into the filling area of ​​the pre-embedded gas injection pipeline. To perform sealing and storage, thereby achieving [the following] The second step is to solidify.

7. The preparation method of the steel slag-based rapid carbonization backfill material according to claim 6, characterized in that, In step S10, the mixing time is 12-24 hours, the stirring speed is 500-1000 r / min, the ultrasonic frequency is 20-40 kHz, and the ultrasonic treatment time is 10-20 min.

8. The preparation method of the steel slag-based rapid carbonization backfill material according to claim 6, characterized in that, In step S20, the mineralization condition is that mineralization is carried out from the bottom of the stirring tank. The purity of carbon dioxide gas is not less than 99.9%, the temperature is 40-60℃, the pressure is 1-5MPa, the mineralization time is 20-40min, and the stirring speed is 500-1000r / min.

9. The preparation method of the steel slag-based rapid carbonization backfill material according to claim 6, characterized in that, In step S50, gas is introduced into the filling area of ​​the pre-embedded gas injection pipeline. The method is as follows: the injection pressure is 2-4 MPa, the flow rate is 5-10 t / h, and the injection time is 4-5 h.

10. The application of a steel slag-based rapid carbonization filling material as described in any one of claims 1 to 5 in the filling of goaf areas in underground coal mines.

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