Mine-used Cemented Backfilling Mortar Material for Mineralizing and Sealing CO2 and Its Preparation Method

Abstract

The present application discloses a mine cementitious filling mortar material for mineralizing and sequestering CO2 and a preparation method thereof, which relates to the technical field of low-carbon environmental protection mortar materials. The raw materials include: microorganisms producing carbonic anhydrase, aggregates, calcium source solution, and nano-zinc oxide; wherein, the calcium source solution is an aqueous solution of calcium chloride, calcium nitrate or calcium acetate, and the calcium source solution includes a premixed calcium source solution and a gradient calcium source solution. Calculated according to Ca 2+ , the concentration of Ca 2+ in the premixed calcium source solution is 0.5 mol / L, and the gradient calcium source solution is 2 mol / L. The premixed calcium source solution is premixed with the aggregates and then used; the particle size of the nano-zinc oxide is 50-100 nm; it can meet the requirements of low-carbon and carbon reduction by increasing the amount of sequestered carbon dioxide, significantly improve the reaction rate of CO2 hydration to generate HCO3 ‑ / CO3 2‑ , accelerate its generation, and then accelerate the CO2 hydration reaction and subsequent gelling action, and improve the environmental protection and low-carbon performance.

Description

Technical Field

[0001] The present invention relates to low-carbon environmental protection mortar materials, and particularly to mine cemented filling mortar materials for mineralizing and sequestering CO2 and a preparation method thereof. Background Art

[0002] The dynamic balance of the generation and consumption of CO2 in nature has enhanced the greenhouse effect of the atmosphere, causing a series of problems such as global warming. This part of CO2 mainly comes from fossil fuel combustion, industrial production, automobile exhaust emissions, etc. Among them, thermal power generation is currently the largest anthropogenic CO2 emission source. In such an environment highly dependent on the fossil fuel power generation mode, how to reduce carbon emissions has become a hot issue of great concern.

[0003] Cemented filling is an important branch of mine filling mining technology. This technology fills the goaf with cementitious materials to support the surrounding rock, reduces the disturbance of mining on the overlying strata, improves the resource recovery rate, and reduces the discharge of waste on the surface, thereby reducing environmental pollution. It has been widely applied worldwide.

[0004] The application of filling mining technology was originally to solve the environmental problems brought about by mine mining. However, the large-scale application of traditional cement-based cemented filling materials has brought problems such as high carbon emissions and high energy consumption caused by cement.

[0005] Therefore, studying a low-carbon filling material that can mineralize and sequester CO2 and is suitable for mine filling mining can not only solve the problem of CO2 sequestration space, but also alleviate the negative environmental effects brought about by traditional cement-based cemented filling materials.

[0006] As in the Chinese patent, application number CN202010921326.3, a mine microbial cemented filling material for mineralizing and sequestering CO2 and a preparation method thereof, the raw materials thereof are composed of CO2, microorganisms, a calcium source, and aggregates. The microorganisms are carbonic anhydrase bacteria producing carbonic anhydrase, which can convert CO2 into CO3 2- , and then combine with the calcium source to form calcium carbonate gelation. The calcium carbonate gelation cements the aggregates to form a cemented filling material. The mine microbial cemented filling material for mineralizing and sequestering CO2 of the present invention can simultaneously achieve the sequestration of CO2 and the consolidation of the filling material. Compared with traditional cement-based cemented filling materials, it not only alleviates the greenhouse effect and reduces carbon emissions, but also ensures that the performance of the filling body meets the technical requirements of mine filling mining while sequestering CO2. The filling material of this invention is a new type of cemented filling material that is environmentally friendly, low in energy consumption, and low in emissions, and has a wide range of application fields and promotion value.

[0007] However, the mixing method is difficult to adapt to complex underground environments and cannot generate gel in situ and penetrate into cracks. Although the perfusion method can generate calcium carbonate gel in situ, due to the fast reaction rate between calcium ions and carbonate ions and the difficulty in uniform distribution, it may result in loose structures or voids. Moreover, the gel generated rapidly and aggregately will cause congestion and reduce the generation efficiency of subsequent gel. Summary of the Invention

[0008] In the embodiments of the present application, by providing a mine cementitious filling mortar material for mineralizing and sequestering CO2 and its preparation method, the problems in the prior art are solved, that is, due to the fast reaction rate between calcium ions and acid radical ions and the difficulty in uniform distribution, it may result in loose structures or voids, and the gel generated rapidly and aggregately will cause congestion and reduce the generation efficiency of subsequent gel. The instant reaction rate between carbonate ions and calcium ions is reduced, avoiding the rapid crystallization of calcium carbonate caused by local supersaturation, and improving the compactness and uniformity of the gel.

[0009] The embodiments of the present application provide a mine cementitious filling mortar material for mineralizing and sequestering CO2, and its raw materials include: microorganisms producing carbonic anhydrase, aggregate, calcium source solution, and nano-zinc oxide;

[0010] Among them, the calcium source solution is an aqueous solution of calcium chloride, calcium nitrate or calcium acetate. The calcium source solution includes a premixed calcium source solution and a gradient calcium source solution. Calculated by Ca 2+ The concentration of Ca 2+ in the premixed calcium source solution is 0.5 mol / L, the gradient calcium source solution is 2 mol / L, and the premixed calcium source solution is used after being premixed with the aggregate; the particle size of the nano-zinc oxide is 50 - 100 nm.

[0011] Furthermore, the microorganisms producing carbonic anhydrase include Bacillus mucilaginosus.

[0012] Furthermore, the aggregate is composed of fine aggregate and coarse aggregate. Among them, the fine aggregate is fly ash, and the coarse aggregate is one or more of tailings or aeolian sand. The mass ratio of the fine aggregate to the coarse aggregate is 1:1; the particle size of the coarse aggregate is ≤ 25 mm, and the particle size of the fine aggregate is ≤ 5 mm.

[0013] The preparation method of the above-mentioned mine cementitious filling mortar material for mineralizing and sequestering CO2 is specifically as follows:

[0014] S1. Inoculate Bacillus mucilaginosus in a culture medium and culture it at 25°C - 37°C for 12 - 24 hours to obtain a seed solution, and then perform an enlarged culture to form a bacterial solution;

[0015] S2. Prepare the calcium source solution; and mix the coarse aggregate, fine aggregate, nano-zinc oxide and the premixed calcium source solution to obtain a premixed aggregate;

[0016] S3. Introduce CO2 gas into the bacterial solution to form a solution containing CO32- Bacterial liquid;

[0017] S4. Transport the premixed aggregate to the underground space to be filled, and then sequentially add the bacterial liquid and the gradient calcium source solution; the volume ratio of the bacterial liquid to the calcium source solution is 1:1;

[0018] S5. Repeat step S4 in a cycle until no liquid flows out of the underground space to be filled, and complete the perfusion filling of the current underground space to be filled.

[0019] Furthermore, the amount of bacteria in the bacterial liquid is 6.0×10 8 CFU / mL.

[0020] Furthermore, in step S2, the mass ratio of the premixed calcium source solution to the aggregate is 1:6.

[0021] Furthermore, the premixed calcium source solution is also mixed with a premixed gelling agent. The mass ratio of the premixed gelling agent to the premixed calcium source solution is 1:5. The premixed gelling agent is prepared by mixing the bacterial liquid, the aggregate, and the calcium source solution. The volume ratio of the bacterial liquid to the aggregate is 1:1, and the Ca 2+ concentration in the calcium source solution is 2 mol / L.

[0022] Furthermore, react the bacterial liquid producing carbonic anhydrase with CO2 gas and the calcium source solution in the aggregate, and collect the gelled product by low-speed centrifugation.

[0023] Furthermore, the premixed gelling agent also contains nano-zinc oxide particles accounting for 1.5% of the mass of the premixed gelling agent; the particle size of the nano-zinc oxide is 50-100 nm.

[0024] Furthermore, the nano-zinc oxide particles are divided into large particles (300-500 nm) and small particles (1-50 nm), and the mass ratio of the large particles to the small particles is 1:2.

[0025] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0026] Firstly, the activity of carbonic anhydrase depends on Zn 2+ as a cofactor. Nano-zinc oxide slowly releases Zn 2+ in the solution, continuously activates the carbonic anhydrase secreted by microorganisms, significantly improves the reaction rate of CO2 hydration to generate HCO3 - / CO3 2- , accelerates its generation, and further accelerates the CO2 hydration reaction and subsequent gelling effect, improving the environmental protection and low-carbon performance; the premixed low-concentration calcium source provides appropriate Ca 2+ in the premixed stage, and initially forms a gelling network with the CO3 2- metabolized by microorganisms, fixes the aggregate particles, and prevents the aggregate from being dispersed or settling and stratifying due to the impact of the subsequent high-concentration gradient calcium solution; the high-concentration Ca2+ It is gradually introduced after the formation of the gelling network, and the precipitation rate of CaCO3 is controlled through the diffusion-reaction coupling mechanism to avoid structural stress cracks caused by rapid crystallization due to local supersaturation; premixing isolates high-concentration Ca 2+ Toxicity: The step-by-step injection of the gradient calcium source avoids the initial high-concentration Ca 2+ The osmotic stress on microorganisms is ensured to be stable at the initial stage of perfusion; the low-concentration solution wets the surface of the aggregate and fills part of the pores, reducing the penetration resistance of the subsequent high-concentration solution and the bacterial solution in the aggregate, making the reaction more sufficient. At the same time, the pre-distributed Ca 2+ When combined with CO3 2- forms calcium carbonate crystal nuclei preferentially on the surface of the aggregate, promoting the directional growth of subsequent crystallization and improving the cementation efficiency.

[0027] Second, the prefabricated gel acts as a ready-made crystal nucleus, significantly reducing the activation energy of calcium carbonate crystallization and increasing the reaction rate; the gel fills the large pores between the aggregates and forms a "gel-newly formed calcium carbonate" composite cementing body through subsequent reactions, further reducing the porosity; the premixed gel forms a continuous transition layer on the surface of the aggregate, reducing the interfacial stress concentration and increasing the bonding strength between the filling body and the aggregate; the microporous structure of the prefabricated gel adsorbs microorganisms, provides attachment sites for them, enhances the local enzyme activity, and improves the CO2 conversion efficiency.

[0028] Third, the hydroxyl groups (-OH) on the ZnO surface are combined with the carboxyl groups (-COOH) of the calcium carbonate gel through hydrogen bonds to form a composite structure of "gel-wrapped nanoparticles"; the Zn 2+ of ZnO undergoes ion exchange with the free CO3 2- in the gel to generate a ZnCO3 transition layer, enhancing the interfacial bonding strength; the surface charge of ZnO (Zeta potential is about -25 mV) can adsorb excessive Ca 2+ to stabilize the free Ca 2+ concentration in the solution at 0.6 - 1.0 mol / L to prevent the death of bacteria caused by excessive calcium ions. The ZnO NPs themselves fill the pores of 10 - 100 nm level; the micron-sized calcium carbonate crystals induced by it fill the pores of 1 - 10 μm level, forming a "nano-micron" double-scale dense structure.

[0029] Fourth, the specific surface area of the small particles reaches 50 - 100 m² / g, providing ultra-high-density nucleation sites to induce the formation of nano-sized calcium carbonate grains; the large particles are dispersed in the gel as "micro-springs", absorbing external impact energy through plastic deformation, and the micropores (2 - 5 nm) on the surface of the large particles can load Ca 2+ which is slowly released during the mineralization process to promote gelling. The combination of large and small particles not only promotes the formation of calcium carbonate grains but also accelerates mineralization, increasing the calcium carbonate gelling speed. Specific implementation methods

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs; the terms used in the specification of this invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0031] Example 1: This application provides a mine cementitious filling mortar material for mineralizing and sequestering CO2, the raw materials of which include: carbonic anhydrase-producing microorganisms, aggregate, calcium source solution, and nano-zinc oxide;

[0032] Among them, the carbonic anhydrase-producing microorganisms include Bacillus mucilaginosus; the aggregate consists of fine aggregate and coarse aggregate, among which the fine aggregate is fly ash, and the coarse aggregate is one or more of tailings or aeolian sand. The mass ratio of the fine aggregate to the coarse aggregate is 1:1; the particle size of the coarse aggregate is ≤25 mm, and the particle size of the fine aggregate is ≤5 mm; the calcium source solution is an aqueous solution of calcium chloride, calcium nitrate, or calcium acetate. The calcium source solution includes a premixed calcium source solution and a gradient calcium source solution. Calculated by Ca 2+ Calculated, the Ca 2+ concentration in the premixed calcium source solution is 0.5 mol / L, and the gradient calcium source solution is 2 mol / L; the particle size of nano-zinc oxide is 50-100 nm;

[0033] The preparation method of the above-mentioned mine cementitious filling mortar material for mineralizing and sequestering CO2 is as follows:

[0034] S1. Inoculate Bacillus mucilaginosus in a culture medium, and culture it at 25°C - 37°C for 12 - 24 hours to obtain a seed solution, and then perform an enlarged culture to form a bacterial solution; the amount of bacteria in the bacterial solution is 6.0×10 8 cells / mL;

[0035] S2. Prepare the calcium source solution; and mix the coarse aggregate, fine aggregate, nano-zinc oxide, and the premixed calcium source solution to obtain a premixed aggregate. The mass ratio of the premixed calcium source solution to the aggregate is 1:6;

[0036] S3. Introduce CO2 gas into the bacterial solution to form a bacterial solution containing CO3 2- ;

[0037] S4. Transport the premixed aggregate to the underground space to be filled, and then sequentially add the bacterial solution and the gradient calcium source solution; the volume ratio of the bacterial solution to the calcium source solution is 1:1;

[0038] S5. Repeat step S4 in a cycle until no liquid flows out of the underground space to be filled, and complete the perfusion filling of the current underground space to be filled.

[0039] The technical solutions in the embodiments of the present application at least have the following technical effects or advantages:

[0040] The activity of carbonic anhydrase depends on Zn 2+ As a cofactor, nano-zinc oxide slowly releases Zn in solution 2+ , continuously activates the carbonic anhydrase secreted by microorganisms, significantly improves the reaction rate of CO2 hydration to form HCO3 - / CO3 2- , accelerates its formation, and then accelerates the CO2 hydration reaction and subsequent gelling action, improving the environmental protection and low-carbon performance;

[0041] Nano-ZnO interacts with the microbial membrane by regulating the surface charge, selectively inhibits the growth of miscellaneous bacteria, and at the same time protects the activity of Bacillus mucilaginosus, maintaining the stability of the mineralization process; the high specific surface energy of nano-ZnO provides heterogeneous nucleation sites for CaCO3 crystal nuclei, reduces the nucleation energy barrier, and promotes the formation of small and uniform calcite crystals, rather than the loose and amorphous structure formed spontaneously; the nanoparticles inhibit the disordered growth of crystals through interfacial adsorption, forming a dense and intertwined micro-nano structure, enhancing the mechanical strength of the cementitious body; nano-ZnO fills the micron-sized pores between aggregates, reduces structural defects, and at the same time its surface hydroxyl groups are combined with the CaCO3 lattice through hydrogen bonds or chemical bonds, enhancing the interfacial adhesion force;

[0042] The premixed low-concentration calcium source provides an appropriate amount of Ca during the premixing stage 2+ , and initially forms a gelling network with CO3 2- metabolized by microorganisms, fixes the aggregate particles, and prevents the aggregates from dispersing or settling and stratifying due to the impact of the subsequent high-concentration gradient calcium solution; the high-concentration Ca 2+ is gradually introduced after the gelling network is formed, and the precipitation rate of CaCO3 is controlled through the diffusion-reaction coupling mechanism, avoiding the generation of structural stress cracks caused by local supersaturation and rapid crystallization; the premixing isolates the high-concentration Ca 2+ toxicity: the stepwise addition of the gradient calcium source avoids the osmotic stress of the initial high-concentration Ca 2+ on microorganisms, ensuring the stability of the bacterial solution activity in the initial perfusion stage; the low-concentration solution wets the surface of the aggregates and fills part of the pores, reducing the subsequent penetration resistance of the high-concentration solution and the bacterial solution in the aggregates, making the reaction more complete. At the same time, the pre-distributed Ca 2+ combines with CO3 2- , and preferentially forms calcium carbonate crystal nuclei on the surface of the aggregates, promoting the directional growth of subsequent crystallization and improving the cementation efficiency;

[0043] The low-concentration solution fills the larger pores between the aggregates, reduces the ineffective penetration of the subsequent high-concentration solution and the bacterial solution, and at the same time retains the tiny pores as the nucleation sites for calcium carbonate crystallization, finally forming an optimized structure of "stable large pores and activated small pores", improving the compressive strength.

[0044] The test results of the properties of the obtained mortar materials are shown in Table 1;

[0045] Table 1

[0046]

[0047] Example 2: In the above example, by premixing aggregates, the density and carbon dioxide sequestration effect are improved, and the low-carbon performance of the material is enhanced. To enhance the filling effect, further improvements are made on the basis of Example 1.

[0048] When preparing the premixed aggregate, the premixed calcium source solution added also contains premixed gelling agent. The mass ratio of the premixed gelling agent to the premixed calcium source solution is 1:5. The premixed gelling agent is prepared by mixing the bacterial solution, aggregate, and calcium source solution. The volume ratio of the bacterial solution to the aggregate is 1:1, and the Ca 2+ concentration in the calcium source solution is 2 mol / L;

[0049] The specific preparation method is: reacting the bacterial solution producing carbonic anhydrase with CO2 gas and calcium source solution in the aggregate, and collecting the gelled product by low-speed centrifugation (1000 rpm).

[0050] The technical solutions in the embodiments of the present application at least have the following technical effects or advantages:

[0051] The prefabricated gelling agent, as a ready-made crystal nucleus, significantly reduces the activation energy of calcium carbonate crystallization, thereby increasing the reaction rate; the gelling agent fills the large pores between the aggregates, and through subsequent reactions, a "gelling agent - newly formed calcium carbonate" composite cementing body is formed, further reducing the porosity; the premixed gelling agent forms a continuous transition layer on the surface of the aggregate, reducing the interfacial stress concentration, and improving the bonding strength between the filling body and the aggregate; the microporous structure of the prefabricated gelling agent adsorbs microorganisms, provides attachment sites for them, enhances the local enzyme activity, and improves the CO2 conversion efficiency;

[0052] Calcium carbonate gelling agent itself has an amorphous or nanocrystalline structure, with a high specific surface area and abundant surface active sites, and can serve as a "pre-nucleation seed", significantly reducing the energy barrier of calcium carbonate crystallization; when synergistically acting with nano-zinc oxide, the two form a composite nucleation network: nano-zinc oxide provides rigid support sites, while calcium carbonate gelling agent adsorbs Ca 2+ and CO3 2- , accelerating heterogeneous nucleation;

[0053] Calcium carbonate gelling agent partially fills the gaps between the aggregates during the premixing stage, forming a preliminary "pre-cementing network", and forms a "dual cementing phase" with the calcium carbonate generated by subsequent microbial mineralization; the amorphous calcium carbonate (ACC) in the gelling agent has high reactivity and gradually transforms into a crystalline state when permeated by the gradient calcium source solution, realizing a gradient increase in the cementing strength;

[0054] Calcium carbonate gelation has an ion buffering capacity. When the Ca concentration in the environment is too high, the gelation adsorbs excessive Ca; when the concentration is insufficient, the gelation dissolves and releases Ca, maintaining the optimal concentration window for microbial mineralization; avoiding the osmotic pressure shock to the cell membrane of Bacillus mucilaginosus caused by directly adding a high-concentration calcium source (Ca > 1.5 mol / L will lead to a decrease in cell dehydration activity). 2+ When the concentration is too high, the gelation adsorbs excessive Ca 2+ ; when the concentration is insufficient, the gelation dissolves and releases Ca 2+ , maintaining the optimal concentration window for microbial mineralization; avoiding the osmotic pressure shock to the cell membrane of Bacillus mucilaginosus caused by directly adding a high-concentration calcium source (Ca 2+ > 1.5 mol / L will lead to a decrease in cell dehydration activity).

[0055] The crystalline calcium carbonate induced by microorganisms combines with the premixed calcium carbonate gelation through hydrogen bonds and ionic bonds to form an "interpenetrating network of crystalline phase - amorphous phase"; the calcium carbonate gelation fills the micron-sized pores between the aggregates, while the microbial mineralization products fill the nano-sized pores, forming a dense structure; the pre-cementation effect of the calcium carbonate gelation in the premixed aggregates shortens the initial setting time of the filling body from 8 - 10 hours to 3 - 4 hours, and reduces the single-well perfusion cycle by 50%; the gel-crystal composite structure inhibits the calcium carbonate dissolution-recrystallization cycle caused by environmental humidity changes, and the strength attenuation rate of the filling body drops from 5% per year to less than 1%.

[0056] The property test results of the mortar material obtained in Example 2 are shown in Table 2;

[0057] Table 2

[0058]

[0059] Example 3: Example 2 was improved on the basis of Example 2 by adding a pre-coagulated gel to increase its initial strength and further improve the density.

[0060] The premixed gelation also contains nano-zinc oxide particles accounting for 1.5% of the mass of the premixed gelation; the particle size of the nano-zinc oxide is 50 - 100 nm.

[0061] The technical solutions in the embodiments of the present application at least have the following technical effects or advantages:

[0062] The hydroxyl groups (-OH) on the ZnO surface combine with the carboxyl groups (-COOH) of the calcium carbonate gel through hydrogen bonds to form a composite structure of "gel encapsulating nanoparticles"; the Zn of ZnO 2+ undergoes ion exchange with the free CO3 in the gel 2- to generate a ZnCO3 transition layer, enhancing the interfacial bonding strength; the surface charge of ZnO can adsorb excessive Ca 2+ , removing the free Ca in the solution 2+The concentration is stabilized at 0.6 - 1.0 mol / L to prevent the death of bacteria caused by excessive calcium ions. ZnO NPs fill the pores at the 10 - 100 nm level by themselves; the micron-sized calcium carbonate crystals induced by them fill the pores at the 1 - 10 μm level, forming a "nano-micron" dual-scale dense structure;

[0063] ZnO NPs form a transition layer about 200 nm thick between the aggregate and the calcium carbonate cementing phase, inhibiting the interfacial cracks caused by the difference in thermal expansion coefficients (the interfacial shear strength is increased from 5 MPa to 12 MPa).

[0064] The property test results of the mortar material obtained in Example 3 are shown in Table 3;

[0065] Table 3

[0066]

[0067] Example 4: The above examples further improve the density and reduce the porosity through the combination of nano-zinc oxide and calcium carbonate cementation. To improve its construction adaptability, it is further improved on the basis of Example 3.

[0068] The nano-zinc oxide particles are divided into large particles (300 - 500 nm) and small particles (1 - 50 nm), and the mass ratio of large particles to small particles is 1:2.

[0069] The technical solutions in the embodiments of the present application at least have the following technical effects or advantages:

[0070] The specific surface area of the small particles reaches 50 - 100 m² / g, providing ultra-high density nucleation sites to induce the formation of nano-scale calcium carbonate crystals; the large particles are dispersed in the gel as "micro-springs", absorbing external impact energy through plastic deformation, and the micropores (2 - 5 nm) on the surface of the large particles can load Ca²⁺ and slowly release it during the mineralization process to promote cementation. The combination of large and small particles not only promotes the formation of calcium carbonate crystals but also accelerates mineralization, increasing the calcium carbonate cementation speed;

[0071] The small-sized ZnO NPs induce the calcium carbonate to orient along the planes of the ZnO lattice in an epitaxial growth mode, forming columnar calcite single crystals; the surface roughness of the large particles promotes the dendritic fractal growth of calcium carbonate crystals, forming a mechanical interlocking structure with the surrounding gel, improving the compressive strength of the overall calcium carbonate cementation;

[0072] The large particles increase the thixotropy of the gel, reducing the viscosity during pipeline transportation of the premixed aggregate and improving the perfusion efficiency. The small particles fill the nano-pores, blocking the water molecule penetration path; forming a hydrophobic interface. The small particles catalyze the decomposition of H + and the large particles consume SO4 2-, cooperate to maintain the material stability. Under extreme environments (humidity 90%, pH 3), the strength attenuation rate decreases from 20% to 5%;

[0073] Small particles catalyze the generation of reactive oxygen species (ROS) to promote the dynamic rearrangement of the gel; large particles store Ca 2+ Trigger secondary mineralization at the crack, enabling self-healing within a certain period of time and having lower requirements for the initial construction.

[0074] The property test results of the mortar material obtained in Example 4 are shown in Table 4;

[0075] Table 4

[0076]

[0077] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A mining cemented filling mortar material for mineralizing and sequestering CO2, characterized in that, Its raw materials include: microorganisms producing carbonic anhydrase, aggregate, calcium source solution, and nano-zinc oxide; Among them, the calcium source solution is an aqueous solution of calcium chloride, calcium nitrate or calcium acetate. The calcium source solution includes a premixed calcium source solution and a gradient calcium source solution. Calculated according to Ca 2+ , the Ca 2+ concentration in the premixed calcium source solution is 0.5 mol / L, the gradient calcium source solution is 2 mol / L, and the premixed calcium source solution is used after being premixed with the aggregate; the particle size of nano zinc oxide is 50 - 100 nm; The premixed calcium source solution is also mixed with premixed gelling agent, and the mass ratio of the premixed gelling agent to the premixed calcium source solution is 1:

5. The premixed gelling agent is prepared by mixing a bacterial solution, aggregate, and calcium source solution. The volume ratio of the bacterial solution to the aggregate is 1:1, and the Ca 2+ concentration in the calcium source solution is 2 mol / L. The premixed gelling agent also contains nano-zinc oxide particles accounting for 1.5% of the mass of the premixed gelling agent. The particle size of the nano-zinc oxide particles is 50 - 100 nm.

2. The mine cementitious filling mortar material for mineralizing and sequestering CO2 according to claim 1, wherein The microorganisms producing carbonic anhydrase include Bacillus mucilaginosus.

3. The mine cementitious filling mortar material for mineralizing and sequestering CO2 as claimed in claim 1, wherein, The aggregate consists of fine aggregate and coarse aggregate. Among them, the fine aggregate is fly ash, and the coarse aggregate is one or more of tailings or aeolian sand. The mass ratio of the fine aggregate to the coarse aggregate is 1:1; the particle size of the coarse aggregate is ≤25 mm, and the particle size of the fine aggregate is ≤5 mm.

4. The preparation method of the mine cemented filling mortar material for mineralizing and sequestering CO2 according to any one of claims 1-3, characterized in that, The preparation method is specifically as follows: S1. Inoculate Bacillus mucilaginosus in a culture medium and culture it at 25°C - 37°C for 12 - 24 hours to obtain a seed solution, and then perform an enlarged culture to form a bacterial solution; S2. Prepare a calcium source solution; mix the coarse aggregate, fine aggregate, nano-zinc oxide, and the premixed calcium source solution to obtain a premixed aggregate; and prepare a pre-coagulated gel, and nano-zinc oxide particles are mixed in the pre-coagulated gel; S3. Introduce CO2 gas into the bacterial solution to form a bacterial solution containing CO3 2- . S4. Transport the premixed aggregate to the underground space to be filled, and then sequentially add the bacterial solution and the gradient calcium source solution; the volume ratio of the bacterial solution to the calcium source solution is 1:1; S5. Repeat step S4 in a cycle until no liquid flows out of the underground space to be filled, and complete the perfusion filling of the current underground space to be filled.

5. The preparation method of the mine cemented filling mortar material for mineralizing and sequestering CO2 according to claim 4, characterized in that, The amount of bacteria in the bacterial solution is 6.0×10 8 CFU / mL.

6. The preparation method of the mine cementitious filling mortar material for mineralizing and sequestering CO2 according to claim 4, characterized in that In step S2, the mass ratio of the premixed calcium source solution to the aggregate is 1:

6.

7. The preparation method of the mine cemented filling mortar material for mineralizing and sequestering CO2 according to claim 5, characterized in that, The preparation method of the pre-coagulated gel is: react the bacterial solution producing carbonic anhydrase with CO2 gas and the calcium source solution in the aggregate, and collect the gel by low-speed centrifugation to obtain the pre-coagulated gel.

8. The preparation method of the mine cemented filling mortar material for mineralizing and sequestering CO2 according to claim 7, characterized in that, The nano-zinc oxide particles are divided into large particles and small particles, and the mass ratio of the large particles to the small particles is 1:2; The particle size of the large particles is 300 - 500 nm; the particle size of the small particles is 1 - 50 nm.

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