A method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide and its application

Abstract

The present invention belongs to the field of hydraulic fracturing and carbon capture, utilization and storage, and specifically relates to a method for preparing a carbon-fixing proppant based on the mineralization reaction of coal-fired power generation solid waste and carbon dioxide and its application. The preparation method comprises the following steps: drying the coal-fired power generation solid waste, dissolving it in an ammonium chloride salt solution with a liquid-solid ratio of 20:1 to the coal-fired power generation solid waste, oscillating it at a constant temperature, filtering the solid phase residue and suspended matter to obtain a mineral suspension; placing the suspension in a high-pressure container for mechanical stirring, adding ammonia water, trishydroxymethylaminomethane catalyst and N,N-dimethylphenylethylamine carbon dioxide adsorbent to a reactor, and injecting CO2 to obtain a CO2 mineralization reaction product; separating the mineralization reaction product into solid and liquid, drying, screening and washing it to obtain a precursor, mixing petroleum ether, phenol and formaldehyde with the precursor, adding ammonia water to react to obtain solid phase particles coated with phenolic resin, and drying and rounding to obtain a carbon-fixing proppant.

Description

Technical Field

[0001] The present invention belongs to the field of hydraulic fracturing and carbon capture, utilization and storage, and specifically relates to a method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide and its application. Background Art

[0002] With the rapid development of economy and society, human demand and consumption of energy are increasing day by day, which in turn leads to increasingly serious emissions of greenhouse gases such as carbon dioxide.

[0003] CCUS (carbon capture, utilization, and storage) is considered a key technology for achieving carbon neutrality. The domestic petrochemical industry and related sectors have systematically conducted research on CCUS technology and established multiple demonstration projects. Sinopec (2022) completed China's first full-process, one-million-ton CCUS project. Upon commissioning, it will reduce CO2 emissions by 1 million tons annually, providing valuable experience for the promotion of CCUS projects. Currently, industries integrating oil and gas field development with CCUS are primarily focused on carbon utilization and storage. Carbon utilization applications in the oil and gas industry include CO2 fracturing, CO2 flooding, CO2 displacement, and enhanced oil and gas recovery. Carbon storage involves storage in abandoned oil and gas reservoirs, saline aquifers, and offshore CO2 hydrates. All of these applications involve injecting CO2 underground in liquid or gaseous form for utilization or storage. Due to the characteristics of CO2 fluids, carbon utilization often results in some injected CO2 being flowed back or produced in the later stages of development. Carbon storage, on the other hand, presents challenges with site selection, monitoring, and complex injection processes.

[0004] To address these issues, the present invention envisions converting gaseous / liquid CO2 into a solid phase through a CO2 mineralization reaction above ground, which can then be utilized or stored in solid form. This approach offers advantages such as safe transportation, ease of operation, and large storage capacity. Hydraulic fracturing is currently the most widely used production-enhancing measure in the oil and gas industry, utilizing solid particles. For example, a well in Weiyuan, Sichuan, underwent 20 fracture stages, utilizing 5,500 tons of proppant. Developing a novel proppant that reduces costs, conserves resources, and contributes to the dual carbon goals is of great significance.

[0005] The present invention proposes a method for preparing a carbon-fixing proppant based on the mineralization reaction of coal-fired power plant solid waste and carbon dioxide. Coal-fired power plant solid waste refers to solid waste generated during the coal combustion process, mainly including fly ash and desulfurized gypsum. Using coal-fired power plant solid waste as a raw material for the CO2 mineralization reaction has the following advantages: (1) The particle size of coal-fired power plant solid waste is small (less than 50 μm), and it does not need to be ground and has a large specific surface area, which allows it to fully contact CO2; (2) Coal-fired power plant solid waste has a wide range of sources, and the cost of using it to prepare proppants is low, and the cost of waste treatment is reduced; (3) Coal-fired power plant solid waste is mostly generated from high-concentration CO2 emission sources such as coalification and thermal power plants. The on-site utilization of the generated waste and CO2 effectively solves the source-sink matching problem of carbon utilization. The prepared carbon-fixing proppant has the following advantages: (1) CO2 is stored in the form of a solid phase, which significantly reduces the requirements for CO2 transportation, storage site selection and leakage monitoring, and is safe and convenient; (2) The prepared proppant has a large carbon fixation capacity, and 1 ton of proppant can store nearly 0.25 tons of CO2. Taking the proppant usage of a typical shale gas well in Sichuan (5,000 tons) as an example, the CO2 storage capacity of a fracturing well is about 1,250 tons; (3) The secondary utilization of industrial waste and the transformation of waste into treasure reduce the cost of proppant preparation and fracturing operation costs.

[0006] CN116063058B discloses a comprehensive utilization method for coal-based solid waste in synergistic carbon dioxide mineralization. The invention extracts calcium and magnesium from coal-based solid waste and reacts them with carbon dioxide to form mineralized slag; then floats the leached ash to obtain flotation tailings, and finally combines the mineralized slag and flotation tailings with an activator to form a 20×20×20mm block of underground filling cementitious material, achieving carbon sequestration and secondary utilization of solid waste. The patent uses coal-based solid waste and carbon dioxide mineralization reaction to form mineralized residue, and the mixture of mineralized slag and tailings is prepared into a block filling cementitious material under the action of different additives. However, the compressive strength of the material (about 10MPa) is relatively low, the utilization of mineralized slag in the patent (accounting for about 20%) is relatively low, and no carbon dioxide mineralization reaction catalyst and adsorbent are added, so the carbon sequestration amount of the gel is unknown.

[0007] CN116790239A discloses a self-generating proppant fracturing fluid that fixes carbon dioxide and its preparation method. The invention injects carbon dioxide into the ground as a fracturing pre-fluid, then injects multiple carbon dioxide additives to chemically react with the carbon dioxide in the pre-fluid to form proppants. This invention achieves carbon dioxide fixation and in-situ proppant generation, effectively reducing proppant wear on the inner wall of the wellbore and improving the fracturing effect. However, this patent uses multiple carbon dioxide additives to react with the pre-fluid carbon dioxide fracturing fluid to form proppant-filled hydraulic fractures underground. The self-generating reaction of the proppant occurs underground and is affected by reservoir heterogeneity and the fracturing construction process. It is difficult to ensure sufficient contact between the CO2 in the pre-fluid and the absorbent / nucleating agent required for the reaction, which in turn affects the reaction degree and the generated proppant concentration distribution, resulting in ineffective support of some fractures and affecting the conductivity. At the same time, the strength of the proppant is still unclear, and the fragmentation of the proppant can also affect the conductivity of the fractures. Therefore, there is an urgent need for a method and application for preparing carbon-fixing proppants based on the mineralization reaction of coal thermal power solid waste with carbon dioxide.

[0008] This patent uses industrial waste coal thermal power solid waste as raw materials and utilizes CO2 mineralization reaction to prepare a new type of carbon-fixing proppant, which has the dual functions of increasing oil and gas production and storing CO2; storing CO2 in solid form broadens the existing technical paradigm of carbon utilization and storage in the oil and gas industry and promotes the development of CCUS technology. Summary of the Invention

[0009] In view of the problems existing in the prior art, the present invention provides a method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide, comprising the following steps:

[0010] S1: drying the coal thermal power solid waste, dissolving it in an ammonium chloride salt solution with a liquid-to-solid ratio of 20:1 to the coal thermal power solid waste, oscillating it at a constant temperature, and filtering the solid phase residue to obtain a solution;

[0011] S2: centrifuging the solution, taking the supernatant, filtering the supernatant to obtain a mineral suspension, placing the suspension in a high-pressure container for mechanical stirring, adding ammonia water, tris(hydroxymethyl)aminomethane catalyst and N,N-dimethylphenylethylamine carbon dioxide adsorbent to the reactor, and injecting CO2 to obtain a mineralization reaction product;

[0012] S3: The mineralization reaction product obtained in S2 is subjected to solid-liquid separation, drying, sieving, and washing to obtain a precursor, petroleum ether, phenol, and formaldehyde are mixed and stirred with the precursor, and ammonia water is added to react to obtain solid phase particles coated with phenolic resin, which are dried and rounded to obtain a carbon-fixing proppant.

[0013] Furthermore, the mass ratio of the tris(hydroxymethyl)aminomethane catalyst to the suspension described in S2 is 1:100, and the mass ratio of the N,N-dimethylphenylethylamine carbon dioxide adsorbent to the suspension is 1:50.

[0014] Furthermore, the constant temperature oscillation described in S1 is at a temperature of 100° C., an oscillation speed of 400 to 600 r / min, and an oscillation time of 10 to 12 h.

[0015] Furthermore, the centrifugal speed described in S2 is 8000-9000 r / min, and the centrifugal time is 6-8 min.

[0016] Furthermore, the stirring temperature in S2 is 60° C., and the stirring rate is 200-300 r / min.

[0017] Furthermore, the ratio of ammonia water to suspension in S2 is 1:10, and the reaction time is 2 to 3 hours.

[0018] Furthermore, the drying time in S3 is 6 to 8 hours, and the drying temperature is 100 to 120°C.

[0019] Furthermore, the mass ratio of petroleum ether to the precursor described in S3 is 1:1, and the mass ratio of ammonia water to the precursor is 10:1.

[0020] Technical Effects

[0021] (1) Product: The present invention provides a carbon-fixing proppant prepared based on the reaction of coal-fired power generation solid waste with carbon dioxide mineralization. The raw materials are industrial waste coal-fired power generation solid waste, which has a wide source and reduces the cost of proppant manufacturing and waste treatment. The pressure resistance of the proppant is enhanced by coating, and the carbon fixation effect is achieved on the basis of meeting the requirements of conventional hydraulic fracturing. The particle size of the coal-fired power generation solid waste is small and is in full contact with carbon dioxide. The amount of carbon fixation in the mineralization reaction is increased by catalysts and adsorbents. The coal-fired power generation solid waste is close to the source of high-concentration carbon dioxide emissions, which effectively solves the problem of source-sink mismatch in carbon utilization. The carbon-fixing proppant buries carbon dioxide in a solid form, is simple and convenient to use, does not require strict control of conditions such as temperature and pressure, has low storage requirements, reduces the requirements for the site selection and monitoring of the storage point, and reduces the risk of carbon dioxide leakage. The interior of the carbon-fixing proppant is a solid phase product of the carbon dioxide mineralization reaction, a carbon dioxide adsorbent, and adsorbed carbon dioxide, and the exterior is a phenolic resin coating structure.

[0022] (2) Preparation method: The present invention provides a method for preparing a carbon-fixing proppant based on the mineralization reaction of coal-fired power generation solid waste and carbon dioxide. The Mg and Ca ions in the coal-fired power generation solid waste react with carbon dioxide to undergo a mineralization reaction. Compared with conventional mineralization reactions, the present invention adds a catalyst and a carbon dioxide adsorbent to the mineralization reaction, thereby increasing the reaction rate and carbon fixation amount of the mineralization reaction.

[0023] (3) Application: The present invention provides an application of a carbon-fixing proppant prepared by reacting coal thermal power solid waste with carbon dioxide mineralization. The application of the carbon-fixing proppant is simple and consistent with the application process of conventional proppant. There is no need to add a complicated process flow, and the construction is simple and safe.

[0024] Attached pictures

[0025] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0026] Figure 1 This is a schematic diagram of the preparation process of the carbon-fixing proppant of the present invention;

[0027] Figure 2 This is a comparison diagram of the sphericity of the proppant before and after the treatment of the present invention;

[0028] Figure 3 This is a diagram showing the experimental results of the proppant breakage rate test of the present invention;

[0029] Figure 4 This is a solubility diagram of the carbon-fixing proppant of the present invention at different pH values ​​and time;

[0030] Figure 5 This is a schematic diagram of the carbon-fixing physical and chemical carbon-fixing structure of the present invention and its application in hydraulic fracturing. DETAILED DESCRIPTION

[0031] The following will be combined with Example 1 of the present invention and the accompanying Figures 1 to 5 The present invention provides a clear and complete description of the technical solution of the present invention. The embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0032] The present invention provides a method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide, comprising the following steps:

[0033] S1: First, the coal thermal power solid waste is dried, then dissolved in ammonium chloride salt solution, placed on a constant temperature oscillator with set temperature and speed, and after the oscillation is completed, the solid residue is filtered;

[0034] S2: Centrifuge the mixed solution of S1, take the supernatant and pass it through a microporous filter membrane to obtain the calcium and magnesium ions in the coal thermal power solid waste dissolved by ammonium chloride salt, forming a mineral suspension that is more easily reacted with carbon dioxide; place the suspension in a high-pressure container and perform mechanical stirring, while opening the air inlet and outlet, passing CO2 gas to expel the air in the container, and then close the outlet. Add ammonia water in a ratio of 1:10 to the suspension into the container, add trishydroxymethylaminomethane catalyst and N,N-dimethylphenylethylamine carbon dioxide adsorbent to accelerate the mineralization reaction rate and increase the carbon fixation amount. After injecting CO2 gas into the high-pressure container until the system pressure reaches 2MPa, close the air inlet and carry out the mineralization reaction. Then, use the ratio of the weight loss caused by carbonate decomposition of the solid product at 600-900℃ to the mass of the solid product after drying at 110℃ before decomposition to calculate the CO2 mass fraction in the coal thermal power solid waste after carbonation and obtain the carbon fixation amount;

[0035] S3: The mineralization reaction product obtained in S2 is subjected to solid-liquid separation; then placed in an oven for drying and sieved to obtain a mineralized product. The mineralized product is washed with deionized water 2-3 times, then washed once with anhydrous ethanol, and finally washed once more with petroleum ether; dried in a constant temperature oven to obtain a pre-treated proppant precursor; the precursor is placed in a three-necked flask, and petroleum ether is added at a liquid-to-solid ratio (ml / g) of 1:1, followed by phenol and formaldehyde, and stirred in a constant temperature water bath. Ammonia water is then added at a liquid-to-solid ratio (ml / g) of 1:10 for reaction, and finally the dried solid is placed in a ball mill for spherical grinding, and sieved through different mesh screens to obtain carbon-fixing proppants of different particle sizes.

[0036] Example 1

[0037] S1: Dry 100g of coal-fired power plant solid waste and dissolve it in a 50g / L ammonium chloride solution (the liquid-to-solid ratio of ammonium chloride solution to coal-fired power plant solid waste is 20:1). Place it on a constant temperature oscillator at a set temperature of 100°C and an oscillation speed of 400r / min. After oscillating for 10h, take out the solid sample;

[0038] S2; The solution in S1 was centrifuged at a speed of 8000r / min for 6 minutes, and the supernatant was filtered through a 1μm microporous filter membrane to obtain the calcium and magnesium ions in the coal thermal power solid waste dissolved by ammonium chloride salt, forming a mineral suspension that is more easily reacted with carbon dioxide; The suspension was placed in a high-pressure container and mechanically stirred at a speed of 200r / min at 60°C. At the same time, the air inlet and outlet were opened, CO2 gas was introduced to expel the air in the container, and then the air outlet was closed. Ammonia water was added to the container at a ratio of 1:10 to the suspension, 2wt% trishydroxymethylaminomethane catalyst and 3wt% N,N-dimethylphenylethylamine carbon dioxide adsorbent were added, CO2 gas was injected into the high-pressure container until the system pressure reached 2MPa, and then the air inlet was closed. The reaction continued for 2 hours; The CO2 mass fraction in the coal thermal power solid waste after carbonation was calculated by using the ratio of the weight loss caused by carbonate decomposition of the solid product at 600°C to the mass after drying at 110°C before decomposition, and the carbon fixation amount per unit mass of the product was obtained;

[0039] S3: The mineralization reaction product obtained in S2 is subjected to solid-liquid separation, placed in an oven at 120°C for 6 to 8 hours, and then sieved to obtain a mineralized product. The mineralized product is washed with deionized water 2 to 3 times, then washed once with anhydrous ethanol, and then washed again with petroleum ether, and finally dried in a constant temperature oven at 100°C for 6 hours to obtain a pre-treated proppant precursor; the precursor is placed in a three-necked flask, and petroleum ether is added at a liquid-solid ratio (ml / g) of 1:1, followed by 8wt% phenol and formaldehyde, and stirred in a constant temperature water bath at 80°C. Then, ammonia water is added at a liquid-solid ratio (ml / g) of 1:10 and reacted for 6 hours; the prepared dry solid is placed in a ball mill and spherical, and sieved through different mesh screens to obtain carbon-fixing proppants of different particle sizes.

[0040] Combine Figure 1 The process of the preparation method of the present invention can be obtained. First, the coal thermal power solid waste is pre-treated by sorting, filtering, etc., and the Ca in the coal thermal power solid waste is removed by ammonium chloride solution. 2+ Mg 2+ Ions are dissolved, and ammonia is used to convert gaseous carbon dioxide into CO3 2- ; Secondly, the dissolved calcium and magnesium ions and carbonate ions are used to obtain the mineralization reaction products of coal thermal power solid waste and CO2, trishydroxymethylaminomethane is used to catalyze the mineralization reaction, and N,N-dimethylphenylethylamine is added to increase the adsorption capacity of CO2 by the mineralization reaction products. The carbon fixation capacity per unit volume of the proppant is increased by combining physical adsorption and chemical reaction. The total carbon fixation capacity includes the sum of the carbon dioxide consumed by the mineralization reaction and the carbon dioxide physically adsorbed after the adsorbent is added. Figure 5As shown; secondly, the mineralized product is prepared into a carbon-fixing proppant through processes such as coating, rounding, and screening, and its sphericity, acid resistance, and compressive strength are close to those of conventional proppants; finally, consistent with the conventional hydraulic fracturing process, the carbon-fixing proppant is pumped into the artificial fracture to achieve the storage of carbon dioxide in solid form and improve the fracture conductivity.

[0041] The carbon-fixing proppant is made of coal-fired power generation solid waste, carbon dioxide, a carbon dioxide adsorbent, a catalyst, an auxiliary agent and a reinforcing agent, wherein the coal-fired power generation solid waste is fly ash and desulfurization gypsum, the catalyst is tris(hydroxymethyl)aminomethane, the carbon dioxide adsorbent is N,N-dimethylphenylethylamine, the auxiliary agent is ammonia water, and the reinforcing agent is petroleum ether, formaldehyde and phenol; the weight proportions of the coal-fired power generation solid waste, the carbon dioxide mineralization reactants and various additives are as follows: fly ash and desulfurization gypsum account for 61-65wt%, carbon dioxide gas (60°C, 2MPa) accounts for 26-29wt%, tris(hydroxymethyl)aminomethane accounts for 1-2wt%, the carbon dioxide adsorbent N,N-dimethylphenylethylamine accounts for 2-3wt%, ammonia water accounts for 1-2wt%, and the reinforcing agent accounts for 8-10wt%.

[0042] The preparation method of this invention is based on the carbonate mineralization reaction between Ca and Mg ions in coal-fired thermal power plant solid waste and CO2. The solid phase product of the reaction undergoes a series of treatments to prepare a proppant. The proppant is then injected into the ground through fracturing, achieving solid-phase storage of CO2 and reservoir transformation.

[0043] Coal thermal power solid waste dissolves Ca in ammonium chloride salt solution 2+ Mg 2+ Ions, the dissolution equation is as follows:

[0044] CaO(s)+2NH4Cl(aq)→CaCl2(aq)+H2O(l)+2NH3(g)

[0045] MgO(s)+2NH4Cl(aq)→MgCl2(aq)+H2O(l)+2NH3(g)

[0046] CaSO4·2H2O(s)+2NH4Cl(aq)→CaCl2(aq)+(NH4)2SO4(aq)+2H2O(l)

[0047] Ammonia promotes the dissolution of CO2 in alkaline solution:

[0048]

[0049] The calcium and magnesium active substances in the solution react with ammonium carbonate to generate CaCO3 and MgCO3. The catalyst is tris(hydroxymethyl)aminomethane, which can maintain the pH of the solution above 9.0, which is beneficial to CaCO3. 2+Mg 2+ With CO3 2- combination.

[0050]

[0051] The solid phase products of the mineralization reaction are coated with phenolic resin to increase the strength of the carbon-fixing proppant, thereby improving the fracture conductivity and fracturing effect. Phenolic resin is a common resin formed by the condensation and curing of phenol and formaldehyde at high temperature. Formaldehyde units can attach to the orthorhombic and para-positions of phenol to form hydroxymethylphenol, which then reacts with the free ortho- or para-positions of another phenol to form a highly cross-linked polymer resin. This three-dimensional network has high hardness, temperature stability, and solvent resistance. In addition, the coated proppant is acid-resistant, which can prevent acidic environments from damaging the CaCO3 and MgCO3 in the proppant.

[0052] Combine Figure 2 , 20 proppant grains were taken before and after rounding treatment to compare the sphericity. The results are as follows Figure 2 As shown, the sphericity of the untreated proppant is relatively low (average roundness 0.5, average sphericity 0.53), and the sphericity (average value) is increased by about 0.3 after the rounding treatment.

[0053] The strength of the proppant is reflected by the crushing rate test. The crushing rate test method refers to the industry recommended standard SY / T5108-2014 "Proppant Performance Test Method for Hydraulic Fracturing and Gravel Packing Operations", and the test temperature is room temperature. Figure 3 As shown, the carbon-fixing proppant in this embodiment has better strength than conventional quartz sand proppant at different closing pressures. When the closing pressure is <40MPa, the strength of the carbon-fixing proppant is well maintained and the crushing rate is 15% lower; when the closing pressure is ≥40MPa, the strength of the carbon-fixing proppant decreases and the crushing rate increases to about 35%, which is comparable to the pressure resistance level of conventional quartz sand. Coating the mineralization reaction product with phenolic resin helps to increase the strength of the proppant and reduce the crushing rate of the proppant. After the carbon-fixing proppant is crushed, the carbon dioxide is still buried underground in a solid form, and safety issues such as carbon dioxide leakage will not occur.

[0054] The acid resistance test refers to the industry standard SY / T 5108-2006 "Performance Indicators and Test Recommendations for Fracturing Proppants" to test the acid solubility of carbon-fixed proppants and conventional quartz sand. The acid resistance of the carbon-fixed proppants in this example is close to that of quartz sand. Acid dissolution tests of carbon-fixed proppants at different temperatures and pH values ​​were conducted. The results are as follows: Figure 4As shown. When the pH is greater than 5, the acid solubility of the carbon-fixing proppant is low (<5%); when the pH is 4, the acid solubility increases to 8.12%; the acid dissolution rate increases with increasing temperature, but the effect on the acid solubility is not significant. The acid resistance of the carbon-fixing proppant is significantly improved by coating with phenolic resin, and the acid solubility is less than 6%. However, since the base material of the proppant is carbonate minerals such as CaCO3 and MgCO3, it is easy to react to produce CO2 in a strong acid environment, which may cause carbon dioxide leakage. Therefore, it is not recommended for use in acidic reservoirs with a pH less than 4.

[0055] The application of the present invention is mainly to obtain the reservoir temperature and fluid pH value of the block based on the existing wells, and screen the reservoir suitable for the carbon-fixing proppant. In accordance with the conventional fracturing process, after circulation and pressure test stabilization, the pre-fluid is injected to generate high pressure at the bottom of the well to fracture the rock and form cracks; the particle size and sand ratio of the carbon-fixing proppant are selected according to the reservoir stress conditions and the fracturing construction design, and the carbon-fixing proppant is transported to the cracks by the sand-carrying fluid; after the sand-mixing fluid is completely injected, the displacement fluid is pumped in to push all the proppant in the pipeline and the wellbore into the cracks to prevent the remaining sand from sinking to the bottom of the well and causing sand blockage.

[0056] Taking the proppant usage of a typical shale gas well in Sichuan (about 5,000 tons) as an example, based on the thermal gravimetric analysis results of the carbon-fixing proppant, it is calculated that its CO2 mass proportion is 25%. If the carbon-fixing proppant is used to complete the fracturing operation, the CO2 storage capacity will be about 1,250 tons.

[0057] The present invention provides a carbon-fixing proppant prepared based on the mineralization reaction of coal thermal power solid waste and carbon dioxide. The proppant has high safety and stability. The carbon-fixing proppant converts carbon dioxide into a solid form, effectively avoiding leakage and formation erosion problems that may be caused by liquid and gaseous carbon dioxide, and improving the safety and stability of the storage process. It also has a high storage capacity. Through the mineralization reaction and the application of carbon dioxide adsorbent, the carbon sequestration capacity is increased by combining physical adsorption and chemical reaction. One ton of carbon-fixing proppant can bury about 0.25 tons of carbon dioxide, providing a way for large-scale stable carbon sequestration. Compared with traditional carbon sequestration technologies, the carbon-fixing proppant has less impact on the environment, is environmentally friendly, helps to reduce greenhouse gas emissions, and combats global climate change. It uses industrial waste coal thermal power solid waste as raw materials, which has a wide source and reduces the cost of proppant manufacturing and waste treatment. The pressure resistance of the proppant is enhanced by coating, and the carbon sequestration effect is achieved while meeting the requirements of conventional hydraulic fracturing. The coal thermal power solid waste is close to the source of high-concentration carbon dioxide emissions, which effectively solves the problem of source-sink mismatch in carbon utilization.

[0058] The present invention provides a method for preparing a carbon-fixing proppant based on the mineralization reaction of coal-fired power generation solid waste and carbon dioxide. The present invention utilizes Mg and Ca ions in the coal-fired power generation solid waste to undergo a mineralization reaction with carbon dioxide. By adding a catalyst to the mineralization reaction, the rate at which carbon dioxide combines with the Mg and Ca ions is significantly increased, thereby accelerating the carbon fixation process and improving the overall reaction efficiency. The use of a carbon dioxide adsorbent can enhance the adsorption capacity of the carbon-fixing proppant for carbon dioxide, allowing more carbon dioxide to be converted into a solid form, thereby increasing the overall carbon fixation amount. In addition, the use of coal-fired power generation solid waste as a raw material realizes the resource utilization of waste, reduces the burden on the environment, and also reduces the preparation cost. Compared with traditional carbon dioxide sequestration technology, the preparation method of the carbon-fixing proppant is simpler, reduces the complexity of the process flow, and reduces the difficulty of operation. By improving the carbon fixation efficiency and simplifying the process flow, the preparation cost of the carbon-fixing proppant is relatively low, and has good economic efficiency. The carbon-fixing proppant prepared by the mineralization reaction and the use of the adsorbent has better stability, can exist stably for a long time in an underground environment, and reduces environmental risks.

[0059] The present invention provides a carbon-sequestering proppant prepared by reacting coal-fired power plant solid waste with carbon dioxide mineralization. This method is simple and convenient to use, does not require strict control of temperature and pressure, is easy to transport and store, reduces requirements for storage site selection and monitoring, and minimizes the risk of carbon dioxide leakage. This carbon-sequestering proppant can be combined with large-scale hydraulic fracturing operations to achieve large-scale carbon sequestration, providing a viable solution for large-scale carbon capture and storage (CCS).

Claims

1. A method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide, characterized in that: S1: drying the coal-fired power generation solid waste, dissolving it in an ammonium chloride salt solution having a liquid-to-solid ratio of 20:1 to the coal-fired power generation solid waste, oscillating the solution at 100° C. and 400-600 rpm for 10-12 hours, and filtering the solid residue to obtain a solution; the coal-fired power generation solid waste is a mixture of fly ash and desulfurized gypsum; S2: The solution of S1 is centrifuged at 8000-9000 r / min for 6-8 minutes, the supernatant is collected, and the supernatant is filtered to obtain a mineral suspension. The suspension is placed in a high-pressure container for mechanical stirring, and ammonia water, tris(hydroxymethyl)aminomethane catalyst, and N,N-dimethylphenylethylamine carbon dioxide adsorbent are added to the reactor, and CO2 is injected for reaction to obtain a mineralization reaction product; S3: The mineralization reaction product obtained in S2 is subjected to solid-liquid separation, drying, sieving, and washing to obtain a precursor, petroleum ether, phenol, and formaldehyde are mixed and stirred with the precursor, and ammonia water is added to react to obtain solid phase particles coated with phenolic resin, which are dried and rounded to obtain a carbon-fixing proppant.

2. The method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide according to claim 1, characterized in that: The mass ratio of the tris(hydroxymethyl)aminomethane catalyst to the suspension described in S2 is 1:100, and the mass ratio of the N,N-dimethylphenylethylamine carbon dioxide adsorbent to the suspension is 1:

50.

3. The method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide according to claim 1, characterized in that: The stirring temperature described in S2 is 60° C., and the stirring rate is 200 to 300 r / min.

4. The method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide according to claim 1, characterized in that: The mass ratio of the ammonia water to the suspension in S2 is 1:10, and the reaction time is 2 to 3 hours.

5. The method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide according to claim 1, characterized in that: The drying time in S3 is 6 to 8 hours, and the drying temperature is 100 to 120°C.

6. The method for preparing a carbon-fixing proppant based on the mineralization reaction of coal thermal power solid waste and carbon dioxide according to claim 1, characterized in that: The mass ratio of petroleum ether to the precursor described in S3 is 1:1, and the mass ratio of ammonia water to the precursor is 10:1.

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