CN-121974626-A - Biochar-based high-porosity carbon storage green filling material and preparation method thereof

CN121974626ACN 121974626 ACN121974626 ACN 121974626ACN-121974626-A

Abstract

A biochar-based high-porosity carbon storage green filling material and a preparation method thereof belong to the field of coal mine filling exploitation. According to the invention, mining solid waste (coal gangue) is taken as a filling skeleton, coal-based solid waste such as coal gangue is selected as a main raw material to combine and react, biological carbon converted from agricultural solid waste (straw) is innovatively introduced, and a carbon dioxide aqueous solution foaming process is adopted to carry out maintenance and carbonization shaping after chemical foaming, so that the high-pore carbon storage green filling material with a three-dimensional network structure with the porosity of more than or equal to 29.09%, the uniaxial compressive strength of 3.85-7.25 MPa in 28 days and the compressive strength of more than or equal to 2.08MPa is prepared. The invention realizes a double carbon fixation mechanism of physical adsorption and chemical mineralization, realizes the resource integration and cooperative treatment of cross-industry solid waste, remarkably improves the resource and environmental benefit of green mine construction, and can provide reliable goaf support for deep mining.

Inventors

QI NAN
HE LEYI
SONG WENWEI
DAI LIANPENG
LIN DAI
LIU TINGLI
WU YUFEI

Assignees

辽宁大学
沈阳工程学院

Dates

Publication Date: 20260505
Application Date: 20260129

Claims (10)

1. The preparation method of the biochar-based high-porosity carbon storage green filling material is characterized by comprising the following steps of: step 1, pretreatment of materials, which is to pretreat solid materials, wherein the solid materials comprise coal gangue, biochar, cement and gypsum, and the liquid raw materials comprise water and carbon dioxide saturated aqueous solution; Step2, preparing slurry, namely mixing the pretreated materials according to a set proportion to obtain a solid mixture, adding water into the solid mixture, and fully and uniformly stirring the mixture to obtain a slurry mixed solution; Step 3, chemical foaming, namely adding a carbon dioxide saturated aqueous solution into the slurry mixed solution to obtain a mixed solution, adding a foam stabilizer accounting for 0.10-0.25% of the volume of the mixed solution into the mixed solution, and continuously stirring until no obvious particles exist, so as to obtain foamed slurry; And 4, curing and carbonizing for shaping, namely injecting the foamed slurry into a mold, curing in a curing box, demolding, and continuing to cure for more than 24 hours under the same environment as the curing box.
2. The preparation method of the biochar-based high-porosity carbon storage green filling material is characterized in that in the step 2, according to the mass ratio, coal gangue fragments, cement, biochar powder, gypsum, water= (80-130), 30-160, 8-60, 9-30 and 80-190 are adopted.
3. The preparation method of the charcoal-based high-porosity carbon storage green filling material according to claim 1 or 2, wherein in the step 1, straw is crushed, dried and pyrolyzed to obtain straw charcoal, the charcoal is crushed for 20-40 min, and charcoal powder with the particle size of 150-200 meshes is obtained after sieving.
4. The preparation method of the charcoal-based high-porosity carbon storage green filling material is characterized in that the preparation process of the straw charcoal comprises the steps of crushing straw into segments with the length of 0.5 cm-1 cm, drying at 60-80 ℃ for 24-48 hours to thoroughly remove water, placing the dried straw into a pyrolysis furnace, programming the temperature of the dried straw to 450-600 ℃ at the temperature rising rate of 5-10 ℃ per minute in an anaerobic environment, keeping the temperature at the pyrolysis temperature for 1-3 hours, naturally cooling to room temperature, and taking out the straw charcoal.
5. The preparation method of the biochar-based high-porosity carbon storage green filling material is characterized in that in the step 1, coal gangue blocks are crushed and dried into uniform fragments, wherein the crushed particles are subjected to primary crushing by a jaw crusher, and are screened by a standard sieve to obtain coal gangue fragments with the particle size of 2.8-5.2 mm; Cement and gypsum are placed in a room temperature dry environment to prevent caking.
6. The method for preparing the biochar-based high-porosity carbon storage green filling material according to claim 1 or 2, wherein in the step 2, an electric stirrer is adopted to stir the solid mixture and water for 10-20 min at a speed of 1500-2500 rpm to obtain a slurry mixed solution.
7. The preparation method of the biochar-based high-porosity carbon storage green filling material is characterized in that in the step 3, deionized water at the temperature of 0-5 ℃ is placed in a closed container, CO 2 is introduced into the container at the rate of 0.3-0.8L/min, and the container is uniformly shaken to obtain a carbon dioxide saturated aqueous solution; The addition amount of the carbon dioxide saturated aqueous solution is 0.10% -0.25% of the volume of the slurry mixed solution.
8. The method for preparing the biochar-based high-porosity carbon storage green filling material according to claim 1 or 2, wherein in the step 4, the curing temperature is (20+/-1) °c, the humidity is more than 95%, and the curing time in a curing box is more than 24 hours.
9. The biochar-based high-porosity carbon storage green filling material is prepared by the method of claim 1 or 2, and is characterized in that the filling material has a three-dimensional network structure with porosity of more than or equal to 29.09%.
10. The biochar-based high-porosity carbon storage green filling material according to claim 9, wherein the filling material has a 28-day uniaxial compression strength of 3.85-7.25 MPa and a 24-hour compression strength of not less than 2.08MPa.

Description

Biochar-based high-porosity carbon storage green filling material and preparation method thereof Technical Field The invention relates to the field of coal mine filling exploitation, in particular to a preparation method of a biochar-based high-pore carbon storage green filling material, and particularly relates to a high-pore green filling material with coupling carbon sealing and anti-impact capabilities and a preparation method thereof. Technical Field In the context of the "two carbon" strategic goal, the coal mining industry is faced with the dual challenges of emissions reduction and development. On the one hand, the conventional cement-based filling materials are themselves high carbon emission sources, and the carbon emissions during the production process may even partially counteract mine emission reduction efforts. On the other hand, deep coal resource exploitation is accompanied with two outstanding problems, namely, firstly, the underground goaf causes stress concentration, the accumulated elastic energy is easy to induce rock burst world mining disasters, secondly, the exploitation process generates a large amount of solid wastes such as coal gangue, and the accumulation of the solid wastes occupies land and causes continuous environmental pollution. Although the traditional gangue filling technology can relieve the surface piling pressure, the material is compact and brittle, has limited energy dissipation control effect on rock burst, and does not have carbon emission reduction function at all. The special geological storage or adsorption carbon fixation technology is high in cost and complex in process, and is difficult to adapt to the severe engineering environment of underground limited space and dynamic disturbance. Therefore, research and development of a novel underground filling material and a system capable of simultaneously achieving the three aims of solid waste recycling, rock burst prevention and carbon dioxide sequestration have become urgent demands for green mine construction. The material has three characteristics, namely, the material has a rich multi-stage pore structure, can provide huge adsorption capacity and diffusion channels for carbon dioxide, can absorb impact energy through a controllable pore crushing mechanism, is a stable solid whole body, can safely seal carbon dioxide for a long time without leakage and can bear stratum pressure, and the material body is derived from solid waste, so that local materials and low-carbon preparation are realized, and new carbon footprints caused by the material are avoided. The method is characterized in that massive agricultural wastes such as straws are produced annually in China, carbon dioxide can be released when the straws are burned in the open air or naturally decomposed, and an efficient and high-valued resource utilization way is found. The biochar prepared by pyrolyzing the straw under the anoxic condition has a highly stable aromatic ring structure, is difficult to be naturally degraded, ensures the long-term stability of the carbon sequestration, creates huge specific surface area for developed micropores and mesopores of the biochar, provides sufficient physical adsorption sites for carbon dioxide molecules, and has abundant alkaline sites and oxygen-containing functional groups on the surface which can also react with carbon dioxide in a chemical mineralization way to generate permanent carbonate so as to realize more stable chemical carbon sequestration. Particularly, the biochar is characterized by being 'carbon negative' in the life cycle, wherein the biochar absorbs atmospheric CO 2 when straw grows, is formed after pyrolysis and stabilization, and is subjected to an active 'carbon removal' process when the biochar is permanently sealed underground. The gangue is used as a primary framework, coarse particles form a stable supporting framework of a macroscopic scale through point contact and friction, and the compressive strength and the structural stability of the material are the most basic. The cement and other cementing materials are used as key binders, and the hydrated calcium silicate and other gel products generated after the hydration reaction can tightly wrap coal gangue and biochar particles and fill gaps between the coal gangue and the biochar particles to form a continuous and compact integral matrix. The straw biochar not only serves as a carbon fixation carrier, but also plays a key role in regulating and controlling microstructure. The self-possessed nano-to-micron porous structure has a huge specific surface energy which provides rich nucleation sites for hydration products, and can promote the hydration process and improve the microstructure of an interface transition zone. The toughness particle characteristics can optimize the internal stress transmission of the material. The physical foaming and carbon dioxide in-situ injection process is introduced, and a multi-stage pore network from macro