A composite geopolymer material, its method of manufacture and use

Abstract

The present application provides a kind of composite geopolymer material and its preparation method and application, belong to geopolymer material technical field.The present application provides system initial alkalinity with soluble salt ions with papermaking black liquor ash, provides aluminum-silicon precursor with coal gangue powder, obtains rheological suitable geopolymer slurry by coupling control of proportioning, particle size and water-binder ratio and is shaped into sample blank;Then CO2-rich liquid is prepared by using composite amine solution to absorb industrial furnace tail gas, the sample blank is soaked for a short time, the CO2-rich liquid is uniformly infiltrated into capillary hole, heated in low temperature and high humidity environment, the CO2-rich liquid is slowly released CO2 in the board, and the gel network evolves synchronously, forms uniform and stable carbonate microcrystal and dense pore wall, rapidly improves the surface density and dimensional stability, realizes the resourceization of CO2 and the closed-loop circulation of amine solution, the process does not need additional NaOH / water glass, the corrosion and safety risk are low, and it is suitable for continuous industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geopolymer materials, and particularly relates to a composite geopolymer material and a preparation method and application thereof. BACKGROUND

[0002] Geopolymer (alkali-activated aluminosilicate) is considered as an ideal material to replace sintered ceramic and organic resin artificial stone as decorative plate due to its low-temperature forming, early strength, high durability and low environmental burden.

[0003] In the prior art, the geopolymer decorative plate process generally relies on an external strong alkali type activator (NaOH, KOH, liquid silicate, etc.), and has the pain points of strong in-situ corrosion, high occupational health and transportation safety risk, limited selection of equipment and material, and high cost and carbon footprint of liquid alkali.

[0004] Carbon dioxide accelerated curing / carbonation curing as a green and low-carbon curing method has shown the comprehensive advantages of shortened age, dense surface layer and CO2 sequestration in the silicate cement system; however, when directly used for carbonation curing of low-calcium or calcium-free geopolymer systems, the pH of the system is often suddenly reduced due to the CO2 acidification effect, and the unreacted gel units are inhibited. + / K + Carbonate crystals migrate out, which further aggravates efflorescence and surface powdering. Especially under gas phase conditions, a dense carbonate "shell layer" is easily formed on the surface, which hinders the further diffusion of CO2 into the interior, resulting in uneven curing and obvious mechanical gradient.

[0005] Therefore, it is necessary to provide a composite geopolymer material and a preparation method and application thereof to solve the above problems. SUMMARY

[0006] The present application provides a composite geopolymer material and a preparation method and application thereof, which uses papermaking black liquor ash to provide initial alkalinity and soluble salt ions of the system, uses un-sintered or low-temperature sintered coal gangue powder to provide aluminum-silicon precursors, and couples ratio, particle size and water-binder ratio to obtain a geopolymer slurry with suitable rheology and to form a sample blank; then a CO2-rich liquid is prepared by using a composite amine solution to absorb industrial furnace tail gas, the sample blank is soaked in the CO2-rich liquid for a short time to make the CO2-rich liquid uniformly penetrate into the capillary pores, and then heated in a medium-low temperature and high humidity environment to promote the CO2-rich liquid to release CO2 in the plate interior, and the CO2-rich liquid and the gel network evolve synchronously to form uniform and stable carbonate microcrystals and dense pore walls, rapidly improving the surface density and dimensional stability, and realizing resource-based sequestration of CO2 and closed-loop circulation of amine liquid. The present process does not require external NaOH / water glass, has low corrosion and safety risk, is suitable for continuous industrial production, and can effectively solve at least one technical problem in the background art.

[0007] In order to solve the above technical problems, the present application is implemented as follows:

[0008] A method for preparing a geopolymer material, comprising the following steps:

[0009] Step S1, 10-30 parts by mass of papermaking black liquor ash, 55-80 parts by mass of coal gangue powder, 0.5-10 parts by mass of a silicon compensation source, and 0.5-10 parts by mass of an inert filler are mixed uniformly, water is added at a water-binder ratio of 0.28-0.40, and then mixed and formed into a geopolymer slurry;

[0010] Step S2, a sample blank is prepared using the geopolymer slurry, and primary curing is performed;

[0011] Step S3, a composite amine solution is prepared, the mass fraction of methyldiethanolamine in the composite amine solution is 20%-40%, the mass fraction of piperazine is 2%-6%, and the balance is deionized water; an industrial furnace kiln tail gas containing CO2 is introduced into the composite amine solution, and the composite amine solution is used to adsorb CO2 to form a CO2-rich liquid;

[0012] Step S4, the CO2-rich liquid is placed in a soaking tank, and the sample blank after primary curing is immersed in the soaking tank;

[0013] Step S5, the sample blank after soaking is placed in a sealed moist heat curing chamber for secondary curing, and the finished product of the geopolymer material is obtained after the secondary curing is completed.

[0014] As a preferred improvement, the papermaking black liquor ash at least includes the following components: 5-20wt% of Na2O and 1-8wt% of K2O; the coal gangue powder at least includes the following components: 20-35wt% of Al2O3 and 45-60wt% of SiO2;

[0015] The papermaking black liquor ash is dried at 95-115℃ for 3-6 hours to constant weight to ensure that the water content is less than 0.5%, and is sieved through a 200-mesh screen to eliminate clumps and large particles; the coal gangue powder is obtained by directly fine grinding or fine grinding after low-temperature calcination of unsintered coal gangue powder, specifically: the unsintered coal gangue powder is directly ball milled to D50 of 8-25μm or is calcined at 600-800℃ for 1-2 hours and then ground to D50 of 8-25μm.

[0016] As a preferred improvement, the silicon compensation source is selected to be waste glass powder or ceramic waste residue powder; the inert filler is selected from one or more of quartz powder, limestone powder, feldspar powder, and kaolin calcination residue.

[0017] As a preferred improvement, the sample blank can be formed by casting or low-pressure pressing process.

[0018] As a preferred improvement, the volume fraction of CO2 in the exhaust gas of the industrial furnace is 8-20%, and in the absorption process of CO2 by the composite amine solution, the temperature is controlled at 35-50℃, the liquid-gas ratio is 1.5-3.0L / Nm 3 , until the CO2 loading degree of the solution α reaches 0.30-0.40 mol CO2 / mol composite amine, the pH of the CO2-rich liquid is between 9.5-10.5, and then the CO2-rich liquid is cooled to 25-35℃ and filtered to remove impurities for storage.

[0019] As a preferred improvement, in the soaking process of step S4, the liquid-solid volume ratio is controlled at 3:1-5:1, the liquid temperature is 25-35℃, the soaking time is 10-45 minutes, and the tank liquid flow rate is maintained at 0.05-0.15m / s by circulating pump during soaking; after soaking, the sample blank is lifted out of the soaking tank at a speed of 10-30mm / s, and is left to drip for 2-5 minutes, leaving only a thin liquid film.

[0020] As a preferred improvement, the relative humidity during secondary curing is maintained at 95%-100% for 6-18 hours; during secondary curing, a controllable process is adopted, which is to first gradually increase the temperature, then maintain the temperature, and finally gradually decrease the temperature: first preheat at 35-45℃ for 10-15min, then increase the temperature to the target 50-60℃ at a rate of 0.5-1.0℃ / min and maintain the temperature for 6-12h, then slowly decrease the temperature to 35-40℃ at a rate of 0.5-1.0℃ / min and maintain the temperature for 30-60min before leaving the room;

[0021] The end point of secondary curing is judged comprehensively by the following indicators:

[0022] The quality gain rate of the finished product is ≤0.1% / h, the total inorganic carbon increase rate of the solution is reduced to ≤0.5mmol / L·h, the surface phenolphthalein discoloration depth is 1-3mm and stable, and there is no frosting on the appearance.

[0023] As a preferred improvement, after step S5, the following steps are further included:

[0024] Step S6, when the CO2 loading degree of the composite amine solution in the soaking tank exceeds 0.40mol CO2 / mol composite amine or the pH decreases to below 9.3, the composite amine solution is transferred to the regeneration system, and air or nitrogen is used as the stripping medium for regeneration treatment, so that the pH of the composite amine solution is restored to 10.2-10.8 and the CO2 loading degree is reduced to 0.10-0.20mol CO2 / mol composite amine. After regeneration, it is cooled to 25-35℃ for reuse.

[0025] A composite geopolymer material is prepared by the above method, wherein the composite geopolymer material has an open porosity of 5%-18%, a 28-day compressive strength of greater than or equal to 40 MPa, a mass loss of less than or equal to 1.0% after 50 freeze-thaw cycles, and a linear dry shrinkage of less than or equal to 0.05%.

[0026] The application of the composite geopolymer material as described above to the preparation of a geopolymer decorative plate, wherein the geopolymer decorative plate comprises a wall tile or a table board.

[0027] The present application has the following advantages:

[0028] (1) The coal gangue powder, as a silicon-aluminum-containing solid waste with abundant reserves, can be used as a main silicon-aluminum precursor after low-temperature calcination or fine grinding activation, realizing resource utilization of a large amount of solid waste; the papermaking black liquor ash is rich in soluble alkali oxides such as Na2O and K2O, which can rapidly release OH - and increase the pH of the system after being mixed with water; thus, the SiO2 and Al2O3 in the coal gangue powder are dissolved to participate in polycondensation, replacing traditional NaOH, Na2SiO3 and other external strong alkali activators, significantly reducing the corrosion, transportation risk and cost, and avoiding high-alkali waste liquid discharge;

[0029] (2) The CO2-rich solution is prepared by capturing CO2 in industrial tail gas through a composite amine solution, and the geopolymer material is soaked and cured at a medium or low temperature, so that the CO2 is uniformly and slowly released in the pores. Compared with direct carbonization of gaseous CO2, this mode avoids surface acidification and the formation of carbonized shells, and the CO2 can penetrate deeply into the interior of the material and gradually react with the pore liquid ions to generate sub-micron to micron-sized carbonate crystals to fill the pore walls, improve the uniformity of the pore structure and the surface density, effectively inhibit ion migration and efflorescence, and ensure the decorative effect and durability of the prepared geopolymer decorative plate; in addition, the composite amine solution can be recycled, the regeneration conditions are mild (100-120 DEG C), the CO2 release efficiency is high, and the solution loss is low, forming a closed-loop system of CO2-amine solution-geopolymer material decorative plate, which improves the utilization rate of the amine solution, reduces the operating cost, realizes large-scale resource utilization and sequestration of CO2, and has the benefits of carbon emission reduction and environment;

[0030] (3) The traditional geopolymer decorative plate needs 7-28 days at room temperature or dry heat to reach stable performance, while the present application only needs 6-18 hours of wet heat curing to obtain a surface density and strength comparable to or even higher than those of the 28-day control group, thus shortening the curing period and improving the mechanical properties. The prepared geopolymer decorative plate has a 7-day compressive strength of 25-40 MPa, a 28-day compressive strength of more than 40 MPa, a flexural strength of more than 9 MPa, a water absorption of 4-6%, a mass loss rate of less than or equal to 1.0% after 50 freeze-thaw cycles, and significantly improved durability and dimensional stability;

[0031] (4) The full use of industrial solid waste and industrial tail gas realizes the high-value resource utilization of multi-source waste and the engineering application of carbon capture and utilization. The preparation process has low energy consumption and high safety. The geopolymer decorative plate product prepared has excellent performance and dense appearance and can be polished, and has significant technical progress, industrialization promotion value and environmental benefits. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0033] The present embodiment provides a preparation method of a composite geopolymer material, comprising the following steps:

[0034] Step S1, 10-30 parts of papermaking black liquor ash, 55-80 parts of coal gangue powder, 0-10 parts of silicon compensation source and 0-10 parts of inert filler are mixed uniformly according to the mass fraction, water is added according to a water-binder ratio of 0.28-0.40 and is mixed and formed into a geopolymer slurry.

[0035] The papermaking black liquor ash is derived from the alkali recovery system of the pulp and paper industry and contains a large amount of Na2O (5-20 wt%), K2O (1-8 wt%), CaO, MgO and part of Na2CO3, Na2SO4, NaOH, etc. It has high soluble alkalinity and the strength is equivalent to 1-5% of additional NaOH solution, and can be used as an internal alkali activator of geopolymer material. The papermaking black liquor ash has fine particles and large specific surface area, is extremely easy to absorb moisture and dissolve, directly causes seepage liquid and dust pollution problems during stacking, and is used as a high-value alkali source in the present application.

[0036] The papermaking black liquor ash is dried at 95-115°C for 3-6 hours to constant weight to ensure that the water content is less than 0.5%, and is passed through a 200-mesh screen to eliminate clumps and large particles and ensure uniform dissolution rate.

[0037] The coal gangue powder is obtained by directly fine grinding or fine grinding after low-temperature roasting of unsintered coal gangue powder. As a byproduct of coal mining, the mineral composition of the coal gangue powder is mainly kaolinite, illite, quartz and feldspar, the content of Al2O3 is usually 20%-35%, and the content of SiO2 is 45%-60%. The unsintered coal gangue powder has low activity, but it can be converted into metakaolin by being ground to D50 of 8-25 μm or being low-temperature roasted at 600-800 ℃, and its activity is significantly improved, and it can dissolve reactive Si and Al units in an alkaline environment. The specific operation mode is: directly ball-milling the unsintered coal gangue powder to D50 of 8-25 μm or roasting at 600-800 ℃ for 1-2 hours and then grinding to D50 of 8-25 μm to stimulate the activity. If necessary, ≤10% of fine waste glass or ceramic waste slag can be added as an additional silicon source.

[0038] The pretreated papermaking black liquor ash and coal gangue powder need to be stored in airtight containers to prevent moisture absorption.

[0039] The silicon compensation source is selected to be fine waste glass or fine ceramic waste slag.

[0040] The principle of the ratio of raw materials is that the equivalent alkali equivalent of the total system is controlled at 1.5%-5.0% Na2Oeq. The papermaking black liquor ash can be mixed with alkali recovery furnace ash to adjust the Na / K ratio and the impurity level.

[0041] Step S2, a sample blank is prepared using the geopolymer slurry, and primary curing is performed.

[0042] The sample blank can be formed by casting or low-pressure pressing process. When casting, it is filled to 95%-100% of the mold cavity and lightly vibrated for 10-20 seconds to remove air bubbles; when pressing, the pressure is controlled at 10-25 MPa, and the pressure is maintained for 10-30 seconds. The primary curing conditions are 25-35 ℃, relative humidity ≥95%, and the duration is 4-8 hours, so that the geopolymer slurry completes initial setting and partial condensation to form a sufficient pore network to facilitate subsequent CO2-rich liquid penetration, while avoiding surface bleeding and early cracking.

[0043] Step S3, a composite amine solution is configured, the mass fraction of MDEA in the composite amine solution is 20%-40%, the mass fraction of PZ is 2%-6%, and the balance is deionized water; the CO2-containing industrial furnace tail gas is introduced into the composite amine solution, and the composite amine solution is used to adsorb CO2 to form a CO2-rich liquid.

[0044] MDEA (Methyldiethanolamine) in the composite amine solution is a tertiary amine, which has good selectivity, low vapor pressure and low energy consumption in regeneration; PZ (Piperazine) is a strong alkaline diamine, which has high reactivity and fast absorption rate. The composite amine solution formed by the combination of the two has high CO2 loading capacity and excellent absorption kinetics. The mass fraction of MDEA in the composite amine solution is 20-40%, the mass fraction of PZ is 2-6%, and the CO2 loading degree can reach 0.25-0.50 mol CO2 / mol composite amine. After absorbing the industrial tail gas, the CO2-rich solution is heated to 50-70°C to release CO2 in a controlled manner. At the same time, the solution has a certain buffering alkalinity and surface wettability, which is suitable for wet immersion curing.

[0045] The volume fraction of CO2 in the industrial furnace tail gas is 8-20%, and the absorption process of CO2 by the composite amine solution is controlled at a temperature of 35-50°C, with a liquid-gas ratio of 1.5-3.0 L / Nm 3 , until the CO2 loading degree of the solution α reaches 0.30-0.40 mol CO2 / mol composite amine. At this time, the CO2-rich solution has a pH of 9.5-10.5, combining CO2 loading and buffering alkalinity. After cooling to 25-35°C and filtering out impurities, it is stored for use. To prevent amine mist loss, the CO2-rich solution preparation system needs to be equipped with a condenser and a water washing tower, and the amine content in the tail gas is controlled at ≤5 mg / Nm 3 .

[0046] Step S4, the CO2-rich solution is placed in the immersion tank, and the sample blank after the first curing is immersed in the immersion tank.

[0047] During the immersion process, the liquid-solid volume ratio is controlled at 3:1-5:1, the liquid temperature is 25-35°C, and the immersion time is 10-45 minutes. During the immersion process, the circulation pump is used to maintain the flow rate of the tank liquid at 0.05-0.15 m / s to avoid dead zones and promote the uniform penetration of CO2-rich solution into the capillary pores. To avoid excessive dissolution of ions, the pH and conductivity of the tank liquid should be monitored in real time. When the conductivity increases by more than 15% of the initial value, the immersion time should be shortened or the flow rate should be reduced. After the immersion is completed, the sample blank is lifted out of the immersion tank at a speed of 10-30 mm / s, and is left to drip for 2-5 minutes, leaving only a thin liquid film.

[0048] The immersion tank can be a batch tank, a roller coating tank or a continuous spray immersion production line. When the thickness of the sample blank is ≥15 mm, double-stage immersion can be used, i.e. using low-concentration CO2-rich solution and high-concentration CO2-rich solution for immersion once respectively. Specifically, first, use low-concentration CO2-rich solution for short-time (such as 10-15 min) immersion to achieve surface wetting and initial penetration, and then use high-concentration CO2-rich solution for deep immersion (such as 20-30 min) to enhance deep CO2 supply and carbonate formation.

[0049] Step S5, the sample blank after soaking is placed in a closed moist heat curing chamber for secondary curing. After the secondary curing is completed, the finished product of the geopolymer material is obtained.

[0050] The relative humidity of the secondary curing is maintained at 95%-100% for 6-18 hours.

[0051] In the closed moist heat curing chamber, the CO2-rich liquid gradually releases CO2 in the pores of the sample blank. The absorbed CO2 in the complex amine solution exists in the form of bicarbonate / carbonate and amine-carbonate; the absorption process is a reversible process: under the conditions of temperature rise, dilution or reduced CO2 partial pressure, the solution can release CO2. During the secondary moist heat curing, the temperature and chemical gradient promote the desorption and diffusion of CO2 from the rich liquid / thin film into the pores of the blank, and react with Ca 2+ , Mg 2+ and alkaline components to form carbonates, fill the pores and form micro-anchoring structures. At the same time, during the secondary curing process, the high pH maintained by the system is mainly buffered by the complex amine (residual MDEA / PZ) and the built-in soluble alkali (Na2Oeq, NaOH / Na2CO3, etc. provided by the papermaking black liquor ash) in the blank, to avoid surface acidification or the formation of a dense carbonized shell.

[0052] During the secondary curing process, a controllable process of gradually increasing the temperature first, then constant temperature, and then gradually decreasing the temperature is adopted: first preheating at 35-45°C for 10-15 min, then increasing the temperature to the target 50-60°C at a rate of 0.5-1.0°C / min and maintaining the temperature for 6-12 h, then slowly decreasing the temperature to 35-40°C at a rate of 0.5-1.0°C / min and maintaining the temperature for 30-60 min before leaving the chamber; for thick plates or systems that require stronger densification, the holding temperature can be appropriately increased to 60-65°C and the holding time can be extended. Humidity control avoids shrinkage cracks caused by capillary water evaporation. The end point of the secondary curing is judged comprehensively by the following indicators: the mass gain of the plate tends to be stable (the increase rate is ≤0.1% / h), the total inorganic carbon (TIC) of the solution decreases to ≤0.5 mmol / L·h, the surface phenolphthalein color changes by 1-3 mm and stabilizes, and there is no frosting on the appearance.

[0053] After the secondary curing is completed, the sample is sprayed with 30-40°C clean water or diluted lean liquid for 0.5-2 minutes to remove the surface residual amine liquid, and then naturally dripped dry or dried at 35-45°C warm air for 5-10 minutes.

[0054] Further, if it is a high-end decorative plate, the prepared sample can also be subjected to step-by-step grinding and polishing (240 mesh→600 mesh→1200 mesh→2000 mesh) to obtain a bright and smooth surface; then 0.2%-0.8% of an organic silicon hydrophobic agent is sprayed to seal the surface micropores, improving the anti-fouling and anti-permeability performance.

[0055] After step S5, the following steps are further included:

[0056] Step S6, when the CO2 loading of the composite amine solution in the soaking tank exceeds 0.40 mol CO2 / mol composite amine or the pH decreases to below 9.3, the composite amine solution is transferred to a regeneration system, and air or nitrogen is used as a stripping medium to perform a regeneration treatment, so that the pH of the composite amine solution is restored to 10.2-10.8, and the CO2 loading is reduced to 0.10-0.20 mol CO2 / mol composite amine. After the regeneration is completed, the composite amine solution is cooled to 25-35°C and reused.

[0057] The temperature condition during the regeneration treatment is 100-120°C, and the flow rate of the stripping medium is 0.8-1.5 Nm 3 / h·m 3 of solution. The CO2 released during the regeneration treatment can be recycled.

[0058] To prevent the accumulation of particles, a solid-liquid separation unit needs to be performed during the regeneration treatment, for example, a filter screen with a mesh size of 5-10 μm is used for filtration, so that the suspended matter is ≤10 mg / L, and the turbidity is ≤5 NTU. According to the material balance, 0.5%-2.0% of fresh MDEA and PZ is added periodically to maintain the stability of the solution.

[0059] The embodiment also provides a composite geopolymer material prepared by using the preparation method of the composite geopolymer material.

[0060] The embodiment also provides an application of the composite geopolymer material, which is used for preparing a geopolymer decorative plate. The geopolymer decorative plate can be used as a common building decorative component, such as a wall tile or a table board. In addition, the geopolymer decorative plate can be filled with a mineral pigment or a colored glass powder to form a colored decorative plate before polishing, so as to further enrich the ornamental property of the surface appearance.

[0061] It is detected that the geopolymer decorative plate prepared by using the method has a dry density of 1.20-1.90 g / cm 3 , an open porosity of 5%-18%, a 24-hour water absorption rate of ≤6%, a 7-day flexural strength of ≥6 MPa, a 28-day flexural strength of ≥9 MPa, a 7-day compressive strength of ≥25 MPa, and a 28-day compressive strength of ≥40 MPa. After 50 cycles of freezing and thawing, the mass loss is ≤1.0%, and the linear dry shrinkage is ≤0.05%. Compared with the traditional dry heat curing, the process can obtain the apparent density and the mechanical property equivalent to 28 days within 6-18 hours, and the curing period is shortened by more than 70%.

[0062] After polishing, the surface glossiness is improved by 10-20 GU, the surface layer electric flux is reduced by 20%-40%, and the anti-fogging ability is improved by one grade.

[0063] The preparation method of the composite geopolymer material provided by the embodiment will be described in detail below.

[0064] Example 1

[0065] In this example, unsintered coal gangue was ball-milled to D50=18 μm for activation treatment, and was used as raw material together with papermaking black liquor ash and CRT waste glass powder in a ratio of 70wt% coal gangue powder, 20wt% papermaking black liquor ash, and 10wt% CRT waste glass powder. After pretreatment, the raw materials were mixed uniformly, and the Na2Oeq content in the papermaking black liquor ash was about 12wt%, and the equivalent alkali equivalent of the system was 3.0%.

[0066] The powders of all raw materials were dry-mixed in a planetary mixer for 1 min, and then water was added twice with a water-binder ratio of 0.35. After stirring, the pH of the geopolymer slurry was 10.6, and the fluidity met the pouring requirements. The geopolymer slurry was poured into a 400x400x10mm mold, and after 15s of light vibration, the surface was smooth. The sample was demolded after 6h of one-time curing in a humid chamber at 30℃ and a relative humidity of ≥95%.

[0067] A composite amine solution was prepared with a ratio of 30wt% MDEA, 5wt% PZ, and the rest being deionized water. The composite amine solution was used to absorb industrial kiln tail gas containing CO2 (volume fraction 12%) to produce a CO2-rich liquid, with an absorption temperature of 40℃ and a liquid-gas ratio of 2.0L / Nm 3 , until the CO2 loading degree α=0.35mol CO2 / mol composite amine, and the pH of the rich liquid was 9.8. The CO2-rich liquid was filtered through a 10μm filter and cooled to 30℃ for standby use.

[0068] The sample blank was immersed in the CO2-rich liquid for 30min, with a liquid-solid ratio of 4:1 and a liquid temperature of 30℃. After lifting out of the immersion tank, the sample was dripped for 3min, forming a thin film on the surface. Then it was placed in a humid heat chamber, initially at a constant temperature of 45℃ for 15min, then linearly heated to 60℃ at a rate of 1.0℃ / min (taking 15min), and after reaching 60℃, the temperature was kept constant, with a total curing time (including the heating section) of 12h, a relative humidity of 98%, and a curing time of 12h to obtain finished product 1.

[0069] The test results show that the 7d compressive strength of finished product 1 is 28MPa, an increase of 35% compared to the control without CO2 wet curing; the 28d compressive strength is 42MPa, and the flexural strength reaches 10.5MPa. The water absorption rate is 5.2%, and the open porosity is 6.8%. The phenolphthalein discoloration depth of the surface layer is ≤1.8mm, and the electric flux is reduced by 32% compared to the control without CO2 wet curing. There is no efflorescence on the surface layer, and the gloss after polishing is increased by 18GU compared to the control without CO2 wet curing. After 50 freeze-thaw cycles, the mass loss rate is 0.9%, and the dimensional shrinkage rate is 0.035%, with excellent performance. The polished surface is dense and smooth, meeting the requirements of high-end decorative boards.

[0070] Example 2

[0071] The coal gangue was calcined at 700℃ for 2h and ground to D50=12μm to obtain metakaolin active powder. The papermaking black liquor ash was dried at 105℃ for 5h and sieved through a 200 mesh screen. The fluorescent lamp tube waste glass powder was ball milled to D50=15μm. The above three were used as raw materials, with a ratio of: calcined coal gangue powder 60wt%, papermaking black liquor ash 25wt%, and waste glass powder 15wt%. The Na2Oeq content of the papermaking black liquor ash was 12wt%; the equivalent alkali equivalent of the system was 4.0%.

[0072] The powders of all raw materials were premixed and stirred with water, with a water-binder ratio of 0.30, a geopolymer slurry pH of 10.9, and a moderate viscosity. The geopolymer slurry was pressed into a 300×300×12mm plate with a pressing pressure of 15MPa and a holding pressure of 20s. After molding, it was cured in a humid chamber at 35℃ and a relative humidity of ≥97% for 4h.

[0073] A composite amine solution was prepared with a ratio of MDEA 25wt%, PZ 4wt%, and the balance being deionized water. The composite amine solution was used to absorb industrial kiln tail gas containing CO2 (volume fraction 15%) to produce a CO2-rich liquid, with an absorption temperature of 40℃ and a liquid-gas ratio of 2.0L / Nm 3 , until the CO2 loading degree α=0.40mol CO2 / mol composite amine, the rich liquid pH=9.7, and the CO2-rich liquid was cooled to 28℃ for standby after being filtered through a 10μm filter.

[0074] The once-cured sample was soaked in the CO2-rich liquid for 20min, with a liquid-solid ratio of 3.5:1 and a liquid temperature of 28℃. After being taken out, it was dripped for 5min and cured in a humid heat chamber at 50℃ and a relative humidity of 99% for 16h to obtain finished product 2.

[0075] The performance test results showed that the 7d compressive strength of finished product 2 was 32MPa, an increase of 42% compared with the control without CO2 wet curing; the 28d compressive strength was 45MPa, and the flexural strength was 11.3MPa. The water absorption rate was 4.0%, and the open porosity was 7.5%. The surface phenolphthalein discoloration depth was ≤2mm, and the electric flux was reduced by 38% compared with the control without CO2 wet curing; the surface was free of efflorescence, and the gloss after polishing was improved by 20.5GU compared with the control without CO2 wet curing. After 50 freeze-thaw cycles, the mass loss rate was 0.8%, and the size shrinkage rate was 0.04%. The polished surface was dense and smooth, meeting the requirements of high-end decorative plates.

[0076] Example 3

[0077] The embodiment selects unsintered coal gangue, which is ball-milled to D50=20 μm, and used as raw material together with alkali recovery furnace ash and waste glass powder in a ratio of 65 wt% of coal gangue powder, 25 wt% of alkali recovery furnace ash, and 10 wt% of waste glass powder. The alkali recovery furnace ash has a Na2Oeq content of 10.5 wt%, and the system has an equivalent alkali equivalent of 3.5%.

[0078] After the powders of all raw materials are uniformly mixed, water is stirred and mixed at a water-binder ratio of 0.33, the geopolymer slurry has a pH of 10.7, and the fluidity meets the pouring requirements. The geopolymer slurry is poured into a 300×300×15 mm mold, and the surface is smooth after light vibration for 15 s and exhaust. The sample is demolded after one-time curing for 5 h in an environment of 30°C and a relative humidity of ≥96%.

[0079] A composite amine solution is configured in a ratio of 30 wt% of MDEA, 5 wt% of PZ, and the rest of deionized water. The composite amine solution is used to absorb industrial kiln tail gas containing CO2 (volume fraction 12%) to prepare a CO2-rich liquid, the absorption temperature is 40°C, the liquid-gas ratio is 2.2 L / Nm 3 , until the CO2 loading degree α=0.38 mol CO2 / mol composite amine, and the pH of the rich liquid is 9.9. The CO2-rich liquid is filtered through a 10 μm filter and cooled to 30°C for standby.

[0080] The once-cured sample is immersed in the CO2-rich liquid for 25 min, the liquid-solid ratio is 4:1, and after being taken out and dripping for 3 min, it is cured at 55°C and a relative humidity of 98% for 14 h.

[0081] After curing, the pH of the CO2-rich liquid decreases to 9.2, the loading degree increases to 0.45 mol CO2 / mol composite amine, and the absorption capacity of the solution obviously decreases.

[0082] The CO2-rich liquid is transferred to a regeneration system, heated to 110°C in the regeneration system, and nitrogen gas is introduced as a stripping medium at a flow rate of 1.0 Nm 3 / h·m 3 of solution. After 1.5 h of regeneration, the CO2 loading degree decreases from 0.45 mol CO2 / mol composite amine to 0.15 mol CO2 / mol composite amine, and the pH of the CO2-rich liquid recovers to 10.5. After the overhead gas of the regeneration system is condensed to recover moisture, the CO2 collection amount is 28 kg, which is equivalent to the net storage amount of 8 pieces of 300×300×15 mm decorative plates. After regeneration, the CO2-rich liquid is cooled to 30°C and reused for curing of the next batch of plates.

[0083] The curing effect verification of the regenerated CO2-rich liquid is as follows: the second batch of decorative plates (prepared with the same ratio) is soaked in the regenerated CO2-rich liquid for 20 min, and the curing condition is 55 DEG C, relative humidity 99%, and 12 h. Performance detection shows that the 7d compressive strength is 29 MPa, which is 30% higher than that of the conventional wet curing control; the 28d compressive strength is 43 MPa, the water absorption rate is 5.0%, the surface phenolphthalein discoloration depth is 2 mm, and there is no frost; after 50 times of freeze-thaw cycles, the mass loss rate is 0.9%, which is equivalent to the performance of the first use of the CO2-rich liquid.

[0084] Through material balance calculation, every 1 m 3 The composite amine solution can complete the curing of about 3 batches (a total of 24 pieces) of decorative plates in the operation window of a=0.15-0.45 mol CO2 / mol composite amine, and the regeneration energy consumption is about 0.9 GJ / t-CO2, which is about 20% lower than that of the conventional MEA system. The solution loss is less than 1.5%, and only 0.5% MDEA and 0.2% PZ need to be added to maintain stable operation.

[0085] The results show that the composite amine solution in the process can be regenerated and used multiple times, ensuring the stability of the CO2-rich liquid wet curing effect, significantly reducing the operating cost, realizing the closed-loop circulation of CO2 capture-building material curing-CO2-rich liquid regeneration, and having economic and environmental benefits.

[0086] The above describes the embodiments of the present application, but the present application is not limited to the above specific embodiments, and the above specific embodiments are only illustrative but not limiting, and those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application, which are all within the protection of the present application.

Claims

1. A method for preparing a composite geopolymer material, characterized in that, Includes the following steps: Step S1: Mix 10-30 parts of papermaking black liquor ash, 55-80 parts of coal gangue powder, 0.5-10 parts of silicon compensation source and 0.5-10 parts of inert filler evenly according to the mass ratio, add water at a water-binder ratio of 0.28-0.40 and stir to form a geopolymer slurry. Step S2: Prepare sample blanks using geopolymer slurry and perform a curing process; Step S3: Prepare a compound amine solution. The mass fraction of methyldiethanolamine in the compound amine solution is 20%-40%, the mass fraction of piperazine is 2%-6%, and the remainder is deionized water. Pass the tail gas of the industrial furnace containing CO2 into the compound amine solution to adsorb CO2 and form a CO2-rich solution. Step S4: Place the CO2-rich solution in the soaking tank and immerse the sample blank after the first curing process into the soaking tank. Step S5: Place the soaked sample blank in a sealed humid heat curing chamber for secondary curing. After the secondary curing is completed, the finished geopolymer material is obtained. The black liquor ash from papermaking contains the following components: 5-20 wt% Na2O and 1-8 wt% K2O; the coal gangue powder contains the following components: 20-35 wt% Al2O3 and 45-60 wt% SiO2. Papermaking black liquor ash is dried at 95-115℃ for 3-6 hours to constant weight, ensuring a moisture content of less than 0.5%, and then passed through a 200-mesh sieve to eliminate lumps and large particles. Coal gangue powder is obtained by directly fine grinding unsintered coal gangue powder or by fine grinding after low-temperature calcination. Specifically, unsintered coal gangue powder is directly ball-milled to a D50 of 8-25μm, or it is calcined at 600-800℃ for 1-2 hours and then ground to a D50 of 8-25μm.

2. The method for preparing the composite geopolymer material according to claim 1, characterized in that, The silicon compensation source is selected as waste glass fine powder or ceramic waste residue fine powder; the inert filler is selected from one or more of quartz powder, limestone powder, feldspar powder and kaolin calcination residue.

3. The method for preparing the composite geopolymer material according to claim 1, characterized in that, The sample blank can be formed by casting or low-pressure pressing.

4. The method for preparing the composite geopolymer material according to claim 1, characterized in that, The volume fraction of CO2 in the exhaust gas of industrial furnaces and kilns is 8-20%. During the adsorption of CO2 by the composite amine solution, the temperature is controlled at 35-50℃, and the liquid-to-gas ratio is 1.5-3.0 L / Nm³. 3 The solution is kept in a CO2 loading α until it reaches 0.30-0.40 mol CO2 / mol composite amine and the pH of the CO2-rich solution is between 9.5 and 10.

5. Then the CO2-rich solution is cooled to 25-35℃ and filtered to remove impurities before being stored for later use.

5. The method for preparing the composite geopolymer material according to claim 1, characterized in that, During the soaking process in step S4, the liquid-to-solid volume ratio is controlled at 3:1-5:1, the liquid temperature is 25-35℃, the soaking time is 10-45 minutes, and the liquid flow rate is maintained at 0.05-0.15m / s by a circulating pump during the soaking process. After soaking, the sample blank is lifted out of the soaking tank at a speed of 10-30mm / s and allowed to stand and drip for 2-5 minutes, leaving only a thin liquid film covering it.

6. The method for preparing the composite geopolymer material according to claim 1, characterized in that, The relative humidity for secondary curing should be maintained at 95%-100% for 6-18 hours. During the secondary curing process, a controllable process of gradually increasing the temperature, then maintaining a constant temperature, and finally gradually decreasing the temperature should be adopted: first, preheat at 35-45℃ for 10-15 minutes, then increase the temperature at 0.5-1.0℃ / min to the target 50-60℃ and maintain the temperature for 6-12 hours, then slowly decrease the temperature at 0.5-1.0℃ / min to 35-40℃ and keep it at that temperature for 30-60 minutes before removing it from the room. The endpoint of secondary maintenance is determined by a comprehensive assessment of the following indicators: The product quality gain rate is ≤0.1% / h, the total inorganic carbon growth rate in the solution is reduced to ≤0.5mmol / L·h, the surface phenolphthalein color change depth is 1-3mm and stable, and there is no blooming on the appearance.

7. The method for preparing the composite geopolymer material according to claim 1, characterized in that, Step S5 is followed by the following steps: Step S6: When the CO2 loading of the compound amine solution in the soaking tank exceeds 0.40 mol CO2 / mol compound amine or the pH drops below 9.3, the compound amine solution is transferred to the regeneration system and regenerated using air or nitrogen as the stripping medium. This process restores the pH of the compound amine solution to 10.2-10.8 and reduces the CO2 loading to 0.10-0.20 mol CO2 / mol compound amine. After regeneration, the solution is cooled to 25-35°C for reuse.

8. A composite geopolymer material, characterized in that, The composite geopolymer material is prepared by the preparation method of any one of claims 1-7. The open porosity of the composite geopolymer material is 5%-18%, the compressive strength at 28 days is ≥40MPa, the mass loss after 50 freeze-thaw cycles is ≤1.0%, and the linear shrinkage is ≤0.05%.

9. An application of the composite geopolymer material as described in claim 8, characterized in that, Used to prepare geopolymer decorative panels, which include wall tiles and countertops.