All-solid waste negative carbon porous brick and preparation method thereof

Abstract

The invention discloses an all-solid-waste negative-carbon porous brick and a preparation method thereof, belongs to the technical field of green building materials for solid waste recycling and CO2 capture-storage-utilization, and particularly relates to a porous brick which takes red mud, steel slag and recycled aggregate as main raw materials, constructs a hierarchical pore structure through low-water-binder-ratio semi-dry pressing molding, and is prepared from the following raw materials in a solid-solid-waste negative-carbon porous brick. And directional carbonization curing is carried out by using cement kiln tail gas CO2 under the conditions of normal temperature and micro pressure, so that the national waste porous brick with negative carbon characteristic is prepared. According to the method, solid waste high doping, CO2 efficient solid storage and product performance synergistic improvement can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of green building materials technology, specifically relating to a porous brick made from solid waste with negative carbon content using cement kiln tail gas and its preparation method. Background Technology

[0002] Currently, red mud, a highly alkaline solid waste generated during alumina production, occupies a significant amount of land resources due to its stockpiling. Its free alkali and trace heavy metal components are easily leached and migrated through rainwater, posing a potential threat to soil and groundwater environments. Steel slag, a typical solid waste from the metallurgical industry, is rich in free CaO and active silicates; however, due to its poor volume stability and large fluctuations in activity, its actual utilization rate in cement and concrete is low. Furthermore, the failure to achieve high-value-added resource utilization of waste concrete aggregates generated from building demolition will also exacerbate the pressure of solid waste stockpiling.

[0003] Traditional clay sintered brick production requires high-temperature firing at over 900℃, resulting in carbon dioxide emissions exceeding 0.2 tons per ton of product. While autoclaved aerated concrete avoids the sintering process, it still requires high-pressure steam curing at around 180℃, leading to high energy consumption. Existing low-temperature solid waste brick technologies, although utilizing solid waste to some extent, still require the addition of over 20% cement or lime as a binder, resulting in relatively high carbon emissions throughout their entire life cycle, making it difficult to meet the low-carbon development requirements of the construction industry.

[0004] Therefore, how to achieve high-volume synergistic utilization of multi-source solid waste while avoiding high-temperature sintering, high-pressure steam curing, and large-scale cement use, and at the same time achieve efficient solidification and storage of carbon dioxide in industrial exhaust gas, has become a key problem that urgently needs to be solved in this technical field. Summary of the Invention

[0005] The purpose of this invention is to provide a porous brick made from solid waste using directional carbon curing of cement kiln exhaust gas and its preparation method. This method integrates high-alkali red mud from the alumina industry, steel slag from ferrous metallurgical processes, and recycled coarse and fine aggregates from building demolition into the same cementitious system. The recycled aggregates serve a dual role as a framework and porosimeter, providing macroscopic structural strength to the product and constructing deep, interconnected gas transport channels. Steel slag and red mud fill the interior of the recycled aggregates, regulating the internal multi-dimensional pore structure. Simultaneously, the calcium-containing phase on the surface of the steel slag and the alkaline components inside the red mud can react with CO2 to form carbonization products, improving the bonding performance between particles. Through this principle, the solid waste incorporation rate is significantly increased, while a multi-scale pore structure is formed internally, promoting the transport and reaction of CO2 within the product during carbonization curing, thereby solving at least one of the technical problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows: This invention provides a method for preparing porous bricks with negative carbon from solid waste, comprising the following steps: Step S1 uses red mud, steel slag from iron and steel metallurgy, and recycled aggregate from building demolition as the main raw materials, with the total mass of the three accounting for 80-90 wt% of the total mass of the ingredients. Step S2: Add steel slag powder, recycled micro powder and 3wt% to 8wt% cement activator to the main raw materials, and stir to form a dry mixture; Step S3: Add water to the dry mixture, control the water-to-binder ratio to be ≤0.18, and stir for 1-3 minutes to obtain a semi-dry mixture; Step S4: The semi-dry material is semi-dry pressed into shape under a pressure of 15MPa to 40MPa to form a green body with a four-level pore network structure consisting of through pores, interstitial pores, self-generated pores, and gel pores, with a porosity of 20vol% to 40vol%. Step S5: Pre-dry and cure the green body; Step S6: Place the pre-dried green billet in a sealed carbonization chamber, introduce cement kiln tail gas with a CO2 volume fraction of 8% to 20%, and perform carbonization curing for 6 to 12 hours at a pressure of 0.05 MPa to 0.20 MPa. Step S7: After carbonization and curing, the product is cured in a room temperature and humid environment for 3 to 7 days to obtain the solid waste negative carbon porous brick.

[0007] Optionally, in step S1, the amount of red mud is 10wt% to 40wt%, the amount of steel slag is 5wt% to 20wt%, and the amount of recycled aggregate from building demolition is 30wt% to 60wt%.

[0008] Optionally, in step S2, the specific surface area of ​​the steel slag powder is not less than 400 m². 2 ·kg -1 The free CaO content is not less than 4 wt%.

[0009] Optionally, in step S4, the pore size ranges of the four-level mesh are as follows: through holes 2mm~10mm, gap holes 0.1mm~2mm, self-generated pores 10μm~100μm, and gel pores less than 10μm.

[0010] Optionally, in step S6, the cement kiln exhaust gas is used directly after being cyclone dust collector, and the relative humidity inside the chamber is controlled at 50% to 85% during the carbonization curing process.

[0011] This invention also provides a porous brick with negative carbon from solid waste prepared by the method, which has a 28-day compressive strength ≥15MPa and a dry density of 1.50 g·cm³. -3 ~2.50g·cm -3 CO2 solids content ≥90 kg·t -1It has a 24-hour water absorption rate of ≤14%, a mass loss of ≤1.5% after 50 freeze-thaw cycles, and a negative carbon emission throughout its life cycle.

[0012] Optionally, the porosity to compressive strength ratio is 1 vol% : 0.4 MPa to 1 vol% : 0.6 MPa.

[0013] Optionally, the total mass of CaCO3, Na2CO3 and calcium aluminate phase in the porous brick body of the all-solid waste negative carbon accounts for 10wt% to 18wt% of the solid mass, of which CaCO3 is the main crystalline phase.

[0014] Optionally, the porous brick body of the all-solid waste negative carbon brick has a brick body of 3×10 4 After the second wheel load test, the mass loss is ≤0.5%, and the acoustic damping coefficient is increased by more than 12%.

[0015] Optionally, the porous brick made entirely of solid waste with negative carbon does not require high-temperature firing or high-pressure steam curing during the manufacturing process, and the heat of carbonization comes entirely from the waste heat of cement kiln exhaust gas.

[0016] Compared with the prior art, the advantages of this invention are as follows: (1) High-efficiency solid waste utilization and co-processing: Red mud, steel slag and recycled aggregate from building demolition are the main raw materials, accounting for 80-90 wt% in total, realizing high-value-added resource utilization of various bulk industrial solid wastes and significantly reducing environmental burden.

[0017] (2) Low carbon or even negative carbon emissions: CO2 in the tail gas of cement kiln is used for targeted carbonization curing. Each ton of product can fix more than 90 kg of CO2, and the net carbon emissions are negative in the whole life cycle carbon accounting.

[0018] (3) Energy saving and green process: No high temperature firing or high pressure steam curing is required. Carbonization curing is carried out under normal temperature and low pressure conditions, and the energy consumption is significantly lower than that of traditional brick preparation process. The waste heat of the exhaust gas is directly utilized without additional heating, further reducing energy consumption.

[0019] (4) Excellent product performance: 28-day compressive strength ≥15MPa, dry density 1.3–1.7g / cm³ 3 Its water absorption rate, freeze-thaw resistance and salt corrosion resistance all meet the standards for blocks and paving bricks, and it has the characteristics of being lightweight, high-strength, weather-resistant and durable.

[0020] (5) Synergistic enhancement of multi-level pore structure: Through coarse-fine bimodal gradation and low water-binder ratio semi-dry pressing process, a four-level pore network of through pores, gap pores, self-generated pores and gel pores is constructed in situ, which not only promotes the rapid penetration and reaction of CO2, but also enhances the density of the structure by filling carbonization products.

[0021] (6) Effective solidification of heavy metals: During the carbonization process, heavy metals such as Pb and Cd in red mud are converted into stable carbonates or silicates and coated by CaCO3 crystal shells and silica-alumina gel. The leaching concentration is lower than the limit for hazardous waste, and the environmental safety is high.

[0022] (7) The process equipment is highly versatile: the mixing, pressing and carbonization equipment used are all mature and universal equipment, with low investment threshold, high flexibility in modification, easy to couple with existing cement production lines, and has the prospect of large-scale promotion.

[0023] (8) Significant economic benefits: The negative carbon attribute can generate additional revenue through carbon trading. At the same time, the raw material cost is low and the energy consumption is low, making the overall economic performance better than traditional sintered bricks or autoclaved bricks.

[0024] In summary, this invention demonstrates significant advantages in solid waste resource utilization, carbon emission reduction, energy conservation and consumption reduction, product performance, and industrial application, and possesses good environmental, economic, and social benefits. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 The flowchart illustrates the preparation method of the all-solid waste negative carbon porous brick provided by this invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The terms "first," "second," etc., used in this specification are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, without limiting the number of objects; for example, the first object can be one or more. Furthermore, in the specification, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0028] Please see Figure 1 As shown in the figure, this invention provides a method for preparing porous bricks with negative carbon from solid waste, comprising the following steps: Step S1 uses red mud, steel slag from iron and steel metallurgy, and recycled aggregate from building demolition as the main raw materials, with the total mass of the three accounting for 80-90 wt% of the total mass of the ingredients. Step S2: Add steel slag powder, recycled micro powder and 3wt% to 8wt% cement activator to the main raw materials, and stir to form a dry mixture; Step S3: Add water to the dry mixture, control the water-to-binder ratio to be ≤0.18, and stir for 1-3 minutes to obtain a semi-dry mixture; Step S4: The semi-dry material is semi-dry pressed into shape under a pressure of 15MPa to 40MPa to form a green body with a four-level pore network structure consisting of through pores, interstitial pores, self-generated pores, and gel pores, with a porosity of 20vol% to 40vol%. Step S5: Pre-dry and cure the green body; Step S6: Place the pre-dried green billet in a sealed carbonization chamber, introduce cement kiln tail gas with a CO2 volume fraction of 8% to 20%, and perform carbonization curing for 6 to 12 hours at a pressure of 0.05 MPa to 0.20 MPa. Step S7: After carbonization and curing, the product is cured in a room temperature and humid environment for 3 to 7 days to obtain the solid waste negative carbon porous brick.

[0029] In step S1, the amount of red mud is 10wt% to 40wt%, the amount of steel slag is 5wt% to 20wt%, and the amount of recycled aggregate from building demolition is 30wt% to 60wt%.

[0030] In step S2, the specific surface area of ​​the steel slag powder is not less than 400 m². 2 ·kg -1 The free CaO content is not less than 4 wt%.

[0031] In step S3, the slump of the semi-dry material generated after adding water and stirring is less than 30mm, to ensure that the pore network is shaped and does not collapse during subsequent pressing and molding.

[0032] In step S4, the pore sizes of the four-level mesh are as follows: through holes 2mm to 10mm, gap holes 0.1mm to 2mm, self-generated pores 10μm to 100μm, and gel pores less than 10μm.

[0033] Furthermore, the molding time for semi-dry pressing is 3s to 15s.

[0034] In step S5, the pre-drying and curing time is determined based on the sample porosity and drying method, so that the relative humidity in the pores inside the pre-cured body is within the range of 50-70%.

[0035] In step S6, the cement kiln exhaust gas is used directly after being cyclone dust removal. During the carbonization curing process, the relative humidity inside the chamber is controlled at 50% to 85%. The moisture generated during the carbonization process is removed in a timely manner and the internal humidity is adjusted by controlling the wind speed inside the carbonization chamber and setting up drainage ditches.

[0036] During the carbonation stage, CO2 reacts with alkali metals such as CaO, Ca(OH)2, and tricalcium silicate in steel slag powder, steel slag particles, recycled aggregates, and micro powders to generate CaCO3 crystal shells and silica / alumina gel. Among them, the calcium carbonate crystal shells form the main skeleton structure, while the silica / alumina gel fills the spaces between the calcium carbonate crystals and improves the bonding performance, increases the skeleton density, and forms strength.

[0037] Trace amounts of heavy metals such as Pb and Cd in red mud precipitate as carbonates or silicates during the carbonation process and are coated with CaCO3 crystal shells and silica / alumina gel. This results in the leaching concentration of heavy metals in the resulting filter residue, as tested by TCLP, being below the hazardous waste leaching limit of GB5085.3. Simultaneously, the alkaline substances in red mud can undergo carbonization reactions, further increasing carbon sequestration and product strength.

[0038] The heat generated by carbonization in the product exhaust gas comes entirely from the waste heat of the cement kiln exhaust gas, requiring no additional heating; the kiln exhaust gas can be used directly after cyclone dust removal, without the need for deep desulfurization, denitrification and purification.

[0039] This invention also provides a porous brick with negative carbon from solid waste prepared by the method, which has a 28-day compressive strength ≥15MPa and a dry density of 1.50 g·cm³. -3 ~2.50g·cm -3 CO2 solids content ≥90 kg·t -1 It has a 24-hour water absorption rate of ≤14%, a mass loss of ≤1.5% after 50 freeze-thaw cycles, and a negative carbon emission throughout its life cycle.

[0040] Furthermore, the porosity to compressive strength ratio of the all-solid waste negative carbon porous brick is 1 vol% : 0.4 MPa to 1 vol% : 0.6 MPa.

[0041] The total mass of CaCO3, Na2CO3 and calcium aluminate phase in the porous brick body of solid waste accounts for 10wt% to 18wt% of the solid mass, among which CaCO3 is the main crystalline phase.

[0042] All-solid-waste negative carbon porous bricks at 3×10 4 After the second wheel load test, the mass loss is ≤0.5%, and the acoustic damping coefficient is increased by more than 12%.

[0043] The porous brick made from solid waste with negative carbon does not require high-temperature firing or high-pressure steam curing during the manufacturing process; the heat of carbonization comes entirely from the waste heat of the cement kiln exhaust gas.

[0044] The following detailed description of the solid waste negative carbon porous brick and its preparation method provided by the present invention is based on specific embodiment 1.

[0045] Example 1 I. Raw Material Preparation and Pretreatment Red mud: Dewatered red mud produced by the Bayer process at an alumina plant in Guangxi, with a room temperature moisture content of approximately 18%. It underwent secondary dewatering using a belt filter, followed by hot air circulation drying at 80℃ for 4 hours to reduce the moisture content to below 8%. After crushing, it was passed through a 5mm rotary sieve for later use. Chemical analysis revealed its main chemical components (mass fraction) to be: Na₂O 8.3%, Al₂O₃ 19.6%, Fe₂O₃ 38.7%, SiO₂ 12.4%, and CaO 4.2%. Its 1:10 water leaching pH value was 11.9.

[0046] Steel slag: Converter cooling slag is used. After being crushed to a particle size of less than 10 mm, metallic iron is removed by magnetic separation. It is then further pulverized by a combination of jaw crusher and impact crusher to particles with a particle size of 0.1–4 mm. Its main components (mass fraction) are: free CaO 4.9%, total CaO 43.1%, SiO2 14.7%, iron oxides 18.3%, and specific surface area of ​​approximately 380 m² / kg.

[0047] Recycled coarse aggregate: derived from discarded C30 concrete components, crushed by a jaw crusher, then screened by a drum screen to select particles with a diameter of 2-10 mm, and washed to remove attached soil. Its surface dry water absorption rate is 4.1%, the content of needle-like and flaky particles is 9.3%, and the crushing index is 14%, which meets the requirements for aggregates used in masonry blocks.

[0048] Steel slag powder: produced from blast furnace water-quenched slag through ball milling and powder selection processes, with a specific surface area of ​​430 m². 2 / kg.

[0049] Regenerated micro powder: Micro powder with a particle size of less than 63μm, which is obtained from construction waste through dry sorting and recovery. Its total active SiO2 and Al2O3 content is about 65%.

[0050] Cement activator: P·O 42.5 grade ordinary Portland cement is used.

[0051] Water: clear water at room temperature.

[0052] II. Ingredients and Mixing Weigh the raw materials according to the following mass ratio: 25 parts red mud, 15 parts steel slag particles, 40 parts recycled coarse aggregate, 8 parts steel slag powder, 8 parts recycled micro powder, and 4 parts cement.

[0053] The weighed red mud, steel slag particles, and recycled coarse aggregate were poured into a 300L planetary forced mixer and mixed in dry mode for 30 seconds to initially break up the raw material lumps.

[0054] Add steel slag powder, recycled micro powder and cement, and continue dry mixing for 30 seconds to form a uniform dry mix.

[0055] Add 16% of the total dry mass of clean water (water temperature 25℃) to the dry mix at once, start the mixer on high speed (second speed) and stir for 120 seconds until the material is evenly mixed and the particles are moist, without water seepage, can be clumped when squeezed by hand and crumble when dropped. At this time, the water-to-binder ratio is 0.16 and the material is in a semi-dry state.

[0056] After mixing, the material is conveyed to the brick press hopper within 10 minutes to prevent excessive evaporation of free water.

[0057] III. Semi-dry pressing molding The YQJ-1000 four-column hydraulic brick press was used, with mold cavity dimensions of 240mm × 115mm × 90mm (standard brick size).

[0058] Each mold is filled with 3.9 kg of semi-dry material. The pressing process includes: 5 seconds of pre-pressing, 3 seconds of main pressing (peak pressure 30 MPa), and holding the pressure at the peak pressure for 2 seconds before unloading, ejecting and demolding to obtain a porous brick green body.

[0059] Thermal imaging showed that the surface temperature rise of the green body was less than 10°C during the pressing process. The volumetric porosity of the green body was measured to be approximately 28%, and the multi-level porous structure remained intact.

[0060] IV. Pre-drying and carbonization curing The pressed green body, along with the pallet, is fed into a 12m³ volume container. 3 Inside a sealed stainless steel carbonization chamber.

[0061] Seal the carbonization chamber, evacuate it to a pressure of -0.01 MPa, and maintain this pressure for 2 hours to pre-dry the green billet.

[0062] The exhaust gas from the cement kiln preheater, after being treated by a cyclone dust collector, is introduced into the silo. The temperature of this exhaust gas is 90 ± 5 ℃, and the volume fraction of CO2 is 12 ± 0.5%.

[0063] Adjust the pressure inside the carbonization chamber to 0.10 MPa, control the gas circulation velocity to 0.8 m / s, and maintain the relative humidity at around 60%. Under these conditions, perform continuous carbonization curing for 10 hours.

[0064] Monitoring showed that the carbonization rate began to decrease significantly after 6 hours, and the reaction basically reached a steady state after 10 hours. The final measured CO2 sequestration was 92 kg / t brick. The brick core temperature dropped from the initial 32℃ to 28℃.

[0065] V. Post-treatment rest and performance testing After carbonization curing is completed, the bricks are moved to a curing room with a temperature of 25℃ and a relative humidity of 60% and left to cure in a closed environment for 5 days.

[0066] The finished bricks underwent performance testing, and the results are as follows: Dry density: 1.45 g / cm³ 3 ; 24-hour water absorption rate: 11.8%; 28-day compressive strength: 17 MPa; CO2 solids content (measured by pyrolysis): 95 kg / t brick.

[0067] XRD phase analysis showed that the brick body mainly contains calcite (CaCO3), dicalcium silicate (C2S), calcium aluminum garnet and other phases.

[0068] SEM-EDS microscopic morphology observation revealed that calcite crystal clusters were embedded in calcium-aluminum-silicate hydrated gel (CASH), and heavy metal elements such as lead (Pb) and cadmium (Cd) were uniformly dispersed without enrichment.

[0069] After 50 freeze-thaw cycles, the mass loss rate was 0.9%; after 30 sulfate wet-dry cycles, the mass loss rate was 1.3%.

[0070] VI. Process Parameter Adjustment and Verification By increasing the steel slag powder content to 10wt% (and adjusting other components accordingly), the CO2 solid content was increased to 102 kg / t, and the 28-day compressive strength reached 20.5 MPa.

[0071] Extending the carbonization curing time to 12 hours can achieve a CO2 solidification capacity of 108 kg / t and a 28-day compressive strength of 18.8 MPa.

[0072] By adjusting the particle size of recycled coarse aggregate to 4-8 mm, the porosity of the resulting brick is approximately 24%, the 28-day compressive strength is increased to 25.2 MPa, and the CO2 retention is 91 kg / t.

[0073] When the free CaO content in the steel slag used is reduced to 3wt%, the CO2 sequestration is 88kg / t, and the compressive strength can still be maintained at 16MPa after 28 days, indicating that the free CaO content is one of the key factors affecting the carbon sequestration rate.

[0074] VII. Environmental and Economic Benefit Assessment Producing 1 ton of finished bricks consumes approximately 37 kWh of electricity. Based on a grid emission factor of 0.55 kg CO2 / kWh, this results in indirect CO2 emissions of approximately 20.4 kg. The exhaust gas conveying fan consumes 6 kWh of electricity, emitting approximately 3.3 kg CO2. The total CO2 emissions during the manufacturing stage are approximately 23.7 kg. Since the process retains 95 kg of CO2, the net emission is -71.3 kg CO2 / t brick. At a carbon price of 80 yuan / ton, approximately 5.6 yuan of additional revenue can be obtained through carbon trading for each ton of bricks produced.

[0075] The above embodiments demonstrate that this invention, through the synergistic effect of high blending of multi-source solid waste, low water-to-binder ratio semi-dry pressing, and directional carbonization curing of cement kiln exhaust gas, can successfully produce negative carbon porous bricks with a 28-day compressive strength of 15-25 MPa and a CO2 solid content of 90-110 kg / t. Compared with traditional clay sintered bricks, this process saves more than 60% of energy and reduces carbon dioxide emissions by more than 120%, providing a feasible industrialization path for the building materials industry.

[0076] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0077] Furthermore, it should be noted that the scope of the methods and systems in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0078] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the scope of protection of the present invention, and all of these forms are within the protection scope of the present invention.

Claims

1. A method for preparing a porous brick with negative carbon from solid waste, characterized in that, Includes the following steps: Step S1 uses red mud, steel slag from iron and steel metallurgy, and recycled aggregate from building demolition as the main raw materials, with the total mass of the three accounting for 80-90 wt% of the total mass of the ingredients. Step S2: Add steel slag powder, recycled micro powder and 3wt% to 8wt% cement activator to the main raw materials, and stir to form a dry mixture; Step S3: Add water to the dry mixture, control the water-to-binder ratio to be ≤0.18, and stir for 1-3 minutes to obtain a semi-dry mixture; Step S4: The semi-dry material is semi-dry pressed into shape under a pressure of 15MPa to 40MPa to form a green body with a four-level pore network structure consisting of through pores, interstitial pores, self-generated pores, and gel pores, with a porosity of 20vol% to 40vol%. Step S5: Pre-dry and cure the green body; Step S6: Place the pre-dried green billet in a sealed carbonization chamber, introduce cement kiln tail gas with a CO2 volume fraction of 8% to 20%, and perform carbonization curing for 6 to 12 hours at a pressure of 0.05 MPa to 0.20 MPa. Step S7: After carbonization and curing, the product is cured in a normal temperature and humid environment for 3 to 7 days to obtain the solid waste negative carbon porous brick.

2. The method according to claim 1, characterized in that, In step S1, the amount of red mud is 10wt% to 40wt%, the amount of steel slag is 5wt% to 20wt%, and the amount of recycled aggregate from building demolition is 30wt% to 60wt%.

3. The method according to claim 1, characterized in that, In step S2, the specific surface area of ​​the steel slag powder is not less than 400 m². 2 ·kg -1 The free CaO content is not less than 4 wt%.

4. The method according to claim 1, characterized in that, In step S4, the pore sizes of the four-level mesh are as follows: through holes 2mm to 10mm, gap holes 0.1mm to 2mm, self-generated pores 10μm to 100μm, and gel pores less than 10μm.

5. The method according to claim 1, characterized in that, In step S6, the cement kiln exhaust gas is used directly after being cyclone dust collector, and the relative humidity inside the chamber is controlled at 50% to 85% during the carbonization curing process.

6. A porous brick containing negative carbon from solid waste, prepared by the method according to any one of claims 1 to 5, characterized in that, Its 28-day compressive strength is ≥15MPa, and its dry density is 1.50g·cm³. -3 ~2.50g·cm -3 CO2 solids content ≥90 kg·t -1 It has a 24-hour water absorption rate of ≤14%, a mass loss of ≤1.5% after 50 freeze-thaw cycles, and a negative carbon emission throughout its life cycle.

7. The porous brick with negative carbon from solid waste according to claim 6, characterized in that, The ratio of porosity to compressive strength is 1 vol% : 0.4 MPa to 1 vol% : 0.6 MPa.

8. The porous brick with negative carbon from solid waste according to claim 6, characterized in that, The total mass of CaCO3, Na2CO3 and calcium aluminate phase in the porous brick body of solid waste accounts for 10wt% to 18wt% of the solid mass, among which CaCO3 is the main crystalline phase.

9. The porous brick with negative carbon from solid waste according to claim 6, characterized in that, The porous brick containing carbon negative from solid waste has a brick body with a thickness of 3×10. 4 After the second wheel load test, the mass loss is ≤0.5%, and the acoustic damping coefficient is increased by more than 12%.

10. The porous brick with negative carbon from solid waste according to claim 6, characterized in that, The porous brick made entirely of solid waste with negative carbon does not require high-temperature firing or high-pressure steam curing during the manufacturing process; the carbonization heat comes entirely from the waste heat of the cement kiln exhaust gas.

Images