Lithium-containing autoclaved lime-sand brick based on electric-coal-steel-construction solid waste and method of manufacturing

Abstract

The application belongs to the technical field of building materials, and relates to a steam-pressure sand-lime brick containing lithium, coal-based, steel and building solid waste and a preparation method thereof. The mixture of the steam-pressure sand-lime brick comprises dry materials and bamboo fibers. The dry materials comprise, in parts by weight, 23-35 parts of recycled coarse aggregate, 40-53 parts of recycled fine aggregate, 10-16 parts of calcareous raw material, 3-7 parts of active raw material, 7-12 parts of fine powder material and 4-8 parts of light material. The bamboo fibers account for 1.8-2.6 vol.% of the volume of the dry materials. The application solves the problem of storage of multiple sources of solid waste, realizes harmless treatment, reduction and resource utilization of the solid waste, and ensures excellent performance of the steam-pressure sand-lime brick, with advantages of light weight, high strength, heat preservation, heat insulation, fire resistance and impermeability, and stable product quality. The application significantly reduces the production cost of enterprises and achieves remarkable economic and social environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and relates to an autoclaved lime-sand brick containing lithium battery, coal-based, steel and construction solid waste and its preparation method. Background Technology

[0002] Autoclaved sand-lime bricks, as a building material with a long history, still occupy an important position in the construction industry. They have the characteristics of high strength, high water resistance and frost resistance, and are not prone to drying shrinkage, which makes them widely used in building parts such as walls, partitions, and floors.

[0003] Although autoclaved sand-lime bricks are currently developing well, there are still the following problems in their production and use: (1) Some autoclaved sand-lime brick enterprises still produce small solid standard bricks, which are heavy, consume a lot of materials, and have poor functionality; (2) The strength of autoclaved sand-lime brick products is generally ≤MU10, which is not suitable for GB 50574-2010 "Unified Technical Specification for Application of Wall Materials"; (3) The surface of autoclaved sand-lime bricks is flat, and the bonding force with ordinary mortar is poor, which can easily lead to low shear strength of the wall; (4) Ordinary autoclaved sand-lime bricks have a larger shrinkage value than sintered bricks, and should be designed and constructed in strict accordance with GB 50003-2011 "Code for Design of Masonry Structures"; (5) Autoclaved sand-lime bricks absorb water slowly and release water slowly, which needs to be paid attention to during construction.

[0004] Currently, with increasingly stringent national environmental protection requirements, the production of autoclaved sand-lime bricks will place greater emphasis on environmental protection and sustainable development, adopting cleaner production processes and equipment. my country's railway construction technology ranks among the world's best, and concrete is the most widely used material in railway construction, generating a massive amount of waste concrete annually. Statistics show that each railway maintenance section in my country replaces an average of 7,000 to 8,000 concrete sleepers annually; the Beijing Railway Bureau alone replaces as many as 1 million waste sleepers annually, bringing the total number of waste concrete sleepers in my country to 200 million. South Korea and the Netherlands also face the problem of massive amounts of waste concrete from railway construction. South Korea generates approximately 200,000 waste concrete sleepers annually, equivalent to 1.4% of the country's total railway sleepers. Apart from a small amount used for parking lot fencing, the majority is buried underground, resulting in low recycling rates. The resource-based reuse of waste railway sleepers can not only solve the problems of land encroachment, environmental pollution, and soil structure damage caused by open-air dumping or landfilling, but also alleviate the current shortage of building materials. It is also a concrete practice for carbon reduction and carbon peaking in the building materials industry.

[0005] Therefore, based on the dual needs of environmental protection and resource utilization of autoclaved sand-lime bricks, it is of great significance to improve product performance while achieving green manufacturing of autoclaved sand-lime bricks. Summary of the Invention

[0006] The main objective of this invention is to overcome the deficiencies in the prior art and provide an autoclaved lime-sand brick containing lithium battery-coal-steel-construction solid waste and its preparation method.

[0007] To achieve the above objectives, the specific technical solution is as follows: This invention provides an autoclaved sand-lime brick containing lithium battery, coal-based, steel and construction solid waste, wherein the mixture of the autoclaved sand-lime brick includes dry materials and bamboo fiber; By weight, the dry material comprises: 23-35 parts recycled coarse aggregate; 40-53 parts recycled fine aggregate; 10-16 parts calcium raw material; 3-7 parts active raw material; 7-12 parts fine powder; and 4-8 parts lightweight material. The bamboo fiber accounts for 1.8~2.6 vol.% of the dry material volume. The recycled coarse aggregate is waste concrete particles with a particle size of 5~12mm; The recycled fine aggregate is waste concrete particles with a particle size of 0.075~4.75mm; The specific surface area of ​​the calcium-based raw material is 400~500 m². 2 / kg; the specific surface area of ​​the active raw material is 400~500m². 2 / kg; the specific surface area of ​​the fine powder is 350~450m². 2 / kg; the specific surface area of ​​the lightweight material is 300~400m². 2 / kg.

[0008] Furthermore, the recycled coarse aggregate and the recycled fine aggregate are made from waste railway sleepers.

[0009] The autoclaved sand-lime brick of this invention is designed with the material structure requirements in mind, forming a multi-scale design pattern from material to structure. This pattern ensures that the multi-scale "powder-sand-stone" raw material system fully leverages the particle size synergistic effect of recycled coarse aggregate, recycled fine aggregate, and composite powder raw materials with different specific surface areas. The composite powder raw material system with different specific surface areas exhibits a significant synergistic effect, guaranteeing the excellent performance of the autoclaved sand-lime brick.

[0010] The use of bamboo fiber in the mixture of autoclaved sand-lime bricks of this invention reduces the linear drying shrinkage rate of autoclaved sand-lime bricks, ensures the appearance quality and dimensional deviation of autoclaved sand-lime bricks, improves the density and tensile strength of autoclaved sand-lime bricks, further strengthens the structure and stability of autoclaved sand-lime bricks, and reduces the risk of cracking.

[0011] This invention utilizes waste materials such as abandoned railway sleepers, lithium slag, desulfurization ash, vanadium-titanium slag, coal gangue, and waste aerated concrete as raw materials to replace traditional materials such as sand and lime. This not only solves the problem of multi-source solid waste accumulation and achieves its harmlessness, reduction, and resource utilization, but also provides raw materials for the production of autoclaved sand-lime bricks, promotes the low-carbon development of building materials, and provides a reliable product guarantee for building good houses in the comprehensive revitalization of rural areas.

[0012] Specifically, the method for preparing the recycled coarse aggregate includes the following steps: A1: Waste concrete particles with a particle size of 8-20mm obtained by crushing waste railway sleepers are shaped and then screened to separate waste concrete particles with a particle size of 5-12mm and waste concrete particles with a particle size of <5mm. A2: Waste concrete particles with a particle size of 5~12mm are washed, screened and dried to obtain recycled coarse aggregate and washed waste concrete particles with a particle size of <5mm.

[0013] Specifically, the method for preparing the recycled fine aggregate includes the following steps: Waste concrete particles with a particle size of <8mm obtained from crushing waste railway sleepers, waste concrete particles with a particle size of <5mm obtained from preparing recycled coarse aggregate, and waste concrete particles with a particle size of <5mm after washing are mixed, shaped, and screened to obtain recycled fine aggregate of 0.075~4.75mm and waste concrete particles of <0.075mm.

[0014] This invention utilizes waste railway sleepers to produce 5-12mm recycled coarse aggregate and 0.075-4.75mm recycled fine aggregate in the mixture of autoclaved sand-lime bricks. Waste concrete particles <0.075mm generated during the production of these two aggregates are co-processed with vanadium-titanium slag as fine powder. No waste is generated during the resource recovery process of waste railway sleepers, achieving standardized, multi-faceted, and high-quality utilization of these materials.

[0015] Furthermore, the method for preparing the calcium raw material includes the following steps: B1 pressing molding: Eggshells and desulfurization ash are mixed and ground to a specific surface area of ​​200~300m². 2 / kg, add water and stir, put into a mold, press into pellets and dry; B2 High-Temperature Calcination: The pellets are calcined at high temperature and then cooled to room temperature to obtain the high-temperature calcined product; the high-temperature calcined product is then ground to a specific surface area of ​​400~500 m². 2 / kg.

[0016] The autoclaved lime-sand brick of this invention uses eggshells and desulfurized ash as calcium raw materials in its mixture, replacing the quicklime used in traditional lime-sand brick production. This reduces CO2 emissions during the limestone-to-quicklime production process, significantly lowers enterprise production costs, and is conducive to achieving the "dual carbon" goals of the building materials industry.

[0017] Furthermore, the mass ratio of the eggshell to the desulfurization ash is 2-4:1; the mass of the water is 8-10% of the total mass of the dry eggshell and the desulfurization ash.

[0018] Furthermore, the high-temperature calcination procedure is as follows: the temperature is raised from 20°C to 200°C at a rate of 4°C / min, and held for 30-40 minutes; then the temperature is raised from 200°C to the required temperature of 750-850°C at a rate of 5°C / min, and held for 40-60 minutes.

[0019] Furthermore, the pressing pressure is 15~25MPa; the size of the pellets is Φ35mm×30mm; making it easier to fully calcine and obtain high-quality calcium raw materials.

[0020] Furthermore, the drying temperature of the pellets is 80℃~100℃, and the drying time is 30~50min.

[0021] Furthermore, the preparation method of the active raw material is as follows: wheat straw is covered with coal gangue particles, and the wheat straw and coal gangue are alternately layered at a volume ratio of 1:1, repeated 2-3 times, followed by calcination. The cooled calcined material is then ground to a powder size of 400-500 μm. 2 / kg.

[0022] The lime-sand brick mixture of this invention utilizes coal gangue and wheat straw as active raw materials, making full use of the carbonaceous components in the coal gangue, reducing the firing temperature and time in the preparation of active raw materials, and simultaneously achieving the synergistic and efficient utilization of coal-based solid waste and agricultural solid waste. The utilization of active raw materials in the lime-sand brick mixture provides active SiO2 and Al2O3 for the autoclaving process of the lime-sand bricks, ensuring the content of hydration products such as tobermorite, the target mineral phase, and guaranteeing the high performance of the finished product.

[0023] Furthermore, the calcination temperature is 450~650℃, the heating rate is 5~10℃ / min, and the calcination time is 3~5h.

[0024] Furthermore, the thickness of the wheat straw layer laid out each time is ≤20cm, and the thickness of the coal gangue particles covering the surface each time is ≤5cm.

[0025] Furthermore, the fine powder consists of waste concrete particles with a particle size of <0.075mm and vanadium-titanium slag in a mass ratio of 1 to 3:1.

[0026] Furthermore, the lightweight material is a particle mixture of lithium slag and waste aerated concrete particles in a mass ratio of 1:2 to 4; preferably, the particle size of the waste aerated concrete is 3 to 5 mm.

[0027] The sand-lime brick mixture of this invention utilizes waste aerated concrete and lithium slag. These two solid wastes are lightweight and porous, effectively reducing the density of autoclaved sand-lime bricks and improving their sound absorption performance, thus effectively reducing noise pollution. Furthermore, the use of waste aerated concrete enhances the thermal insulation and sound absorption performance of the autoclaved sand-lime bricks, achieving a balance between density, strength, and thermal insulation. The application of this material contributes to the green development of the building industrialization, providing a guarantee for achieving the "dual carbon" goals of the construction industry and ensuring the safe use of buildings.

[0028] Furthermore, the bamboo fiber has a diameter of 30~65um and a length of 5~25mm.

[0029] Furthermore, the bamboo fiber is made from waste bamboo poles through washing, drying, crushing, and grinding.

[0030] Preferably, the following raw materials are pretreated: The pretreatment of the waste railway sleepers involves removing the track spikes, bolts, and other fixing items from the waste railway sleepers; then, the waste railway sleepers are crushed using an impact drill, and the resulting steel bars and waste concrete are sorted.

[0031] The eggshell pretreatment involves crushing the eggshells, rinsing them with water, and then air-drying them in a cool place. The air-dried eggshell particles are then placed in a 105°C electric heating drying oven and dried to a constant weight. The pretreatment of the desulfurization ash residue is as follows: after removing organic impurities by sieving, the desulfurization ash residue is placed in an electric heating forced-air drying oven at 105℃ and dried. The coal gangue pretreatment involves screening out organic impurities and then crushing the coal gangue into particles ≤5mm. The wheat straw pretreatment involves cutting the naturally air-dried wheat straw into short sections of 1-5 cm. The vanadium-titanium slag pretreatment involves screening out impurities and organic matter from the vanadium-titanium slag and then drying it in a 105°C electric heating blast drying oven until it reaches a constant weight. The lithium slag pretreatment involves sieving out impurities from the lithium slag and then drying it in a 105°C electric heating oven until it reaches a constant weight. The pretreatment of waste aerated concrete involves: after screening out bricks and organic matter, the waste aerated concrete is cut into blocks with a length of less than 20cm, a thickness of less than 5cm, and a width of less than 10cm; the blocks of waste aerated concrete are then crushed into particles of 3-5mm and dried in an electric heating forced-air drying oven at 105℃ until constant weight is achieved. The pretreatment of waste bamboo poles involves removing the attached substances from the surface of the waste bamboo poles, rinsing them with high-pressure water, and then drying them. Then, bamboo pole sections of 150-250mm in length are cut and placed in a 70℃ forced-air drying oven to dry until the moisture content is ≤10%.

[0032] Specifically, the composition of the following raw materials is as follows: The main mineral phases of the eggshell are calcite and aragonite, and its main composition is: CaCO3 78~95%, MgCO3 2~9%, Ca3(PO4)2 0.1~3%, SiO2 0.1~3%, Al2O3+CaO+Fe2O3 0.1~3%, and loss on ignition 5~15%; The main components and contents of the desulfurization ash are as follows: CaO 55~58%, SO3 35~38%, Cl 1.5~1.8%, F 1.5~1.7%, MgO 1.1~1.3%, SiO2 0.8~1%, Al2O3 0.4~0.5%, Fe2O3 0.2~0.3%, K2O 0.1~0.15%; the main mineral components are: CaSO3 10~20%, CaO 25~40%, CaSO4 43~55%. The main mineral phases of the coal gangue are quartz and clay minerals (kaolinite, illite, montmorillonite and muscovite), and siderite. Its main chemical composition and content are: SiO2 40~60%, Al2O3 20~30%, K2O 1~5%, MgO 1~3%, Na2O+K2O 1~4%, Fe2O3 5~15%, CaO 1~5%, and loss on ignition 25~40%. The main mineral composition of the vanadium-titanium slag is magnesium rhodochrosite and perovskite, with the following main chemical components and contents: SiO2 27~33%, CaO 30~35%, Al2O3 8~15%, MgO 8~12%, Fe2O3 5~10%, SO3 0.1~3%, K2O+Na2O 0.1~2%, TiO2 5~10%, and loss on ignition 0.1~3%. The main mineral composition of the lithium slag is quartz, spodumene, gypsum, etc., and its chemical composition and content are: CaO 22~30%, SiO2 45~55%, Al2O3 16~22%, SO3 18~23%, Fe2O3 0.1~3%, and others 0.1~3%; The main mineral composition of the waste aerated concrete is quartz, tobermorite, calcite and CSH gel, and its main chemical components and contents are: SiO2 40~60%, Al2O3 3~8%, CaO 20~30%, MgO 1~5%, Fe2O3 1~5%, SO3 1~5%, K2O+Na2O 0.1~2%, and loss on ignition 5~15%; The main chemical elements of the bamboo fiber are: C 40~50%, H 2~9%, O 42~50%, N 0.1~2%, S 0.01~0.3%, and ash 3~10%. The main chemical composition is: total cellulose 45~55%, lignin 20~25%, and α-cellulose 32~43%.

[0033] The present invention also provides a method for preparing the above-mentioned sand-lime brick mixture, comprising the following steps: S1: Mix recycled coarse aggregate, recycled fine aggregate, calcareous raw materials, active raw materials, fine powder and lightweight materials, add 8-13 parts water and 0.9-1.3 vol.% bamboo fiber (by dry volume), stir at 25-35 rpm for 8-13 minutes, and let stand for 1.5-3 hours to obtain the initial mixture. S2: Add 1-3 parts water and 0.9-1.3 vol.% bamboo fiber (by dry volume) to the initial mixture and stir for 5-7 minutes to obtain the mixture.

[0034] The present invention further provides an autoclaved sand-lime brick, which is prepared by pressing and autoclaving the above-mentioned sand-lime brick mixture.

[0035] The autoclaved sand-lime bricks prepared by this invention integrate advantages such as high strength, low water absorption, low linear drying shrinkage, strong frost resistance, high carbonization coefficient, and high softening coefficient compared to commercially available autoclaved sand-lime bricks. This reduces the breakage rate during transportation and use, and improves product durability and strength. Furthermore, the role of these autoclaved sand-lime bricks in reducing carbon emissions throughout the entire building lifecycle is significant, providing a feasible approach and reference for the low-carbon transformation of the construction industry.

[0036] Furthermore, the pressing pressure is 16~24kN; the autoclaving temperature is 170~195℃, the pressure is 1.1~1.3MPa, the constant temperature and pressure time is 6~10h, and the cooling and depressurization time is 1~3h.

[0037] Preferably, the autoclaved sand-lime brick has dimensions of 240mm × 115mm × 53mm; its dimensions can be customized as needed.

[0038] Compared with the prior art, the present invention has the following significant advantages: The sand-lime brick mixture provided by this invention uses railway solid waste, kitchen waste, steel solid waste, coal-based solid waste, lithium battery solid waste, construction solid waste, agricultural and forestry solid waste, etc. as raw materials, which makes full use of solid waste, reduces CO2 emissions and resource consumption, solves the problem of multi-source solid waste accumulation, and realizes its harmlessness, reduction and resource utilization. It is in line with the current green and low-carbon overall development concept and achieves good economic and social benefits. Moreover, the composition is scientific and standardized, and the multi-source solid waste plays a synergistic role, so that the physical and mechanical properties of autoclaved sand-lime bricks meet the requirements of "Autoclaved Sand-Lime Solid Bricks and Solid Blocks" (GB / T11945-2019).

[0039] The composition and content ratio of minerals in the sand-lime brick mixture of this invention ensures the excellent performance of autoclaved sand-lime bricks, which have advantages such as lightweight and high strength, thermal insulation, fire resistance and impermeability. Their strength grade meets or exceeds MU30 in GB / T 11945-2019 "Autoclaved Sand-Lime Solid Bricks and Solid Blocks", and their frost resistance meets the D50 index requirement for extremely cold regions. Furthermore, water absorption, carbonation coefficient, softening coefficient, and linear drying shrinkage all meet standard requirements, and the product quality is stable. This significantly reduces the production cost for enterprises, resulting in significant economic and social environmental benefits, and is expected to be widely used.

[0040] Autoclaved sand-lime bricks prepared from the sand-lime brick mixture of this invention can replace traditional clay bricks and are suitable for civil buildings, industrial plants and frame structure infill walls, promoting the low-carbon development of building materials and providing reliable product guarantees for building good houses in the comprehensive revitalization of rural areas. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 This is a SEM image of the vanadium-titanium ore slag, the raw material for this invention. (a) Longitudinal (×50), (b) Cross section (×100); Figure 2 Here is a SEM image of the lithium slag used as a raw material in this invention; Figure 3 This is a SEM image of the waste aerated concrete used as a raw material in this invention. (a) Magnified 50 times, (b) Magnified 5000 times; Figure 4 This is a SEM image of bamboo fiber, the raw material for this invention. (a) Longitudinal (×5000), (b) Cross-section (×500); Figure 5 The XRD pattern of the desulfurization ash residue used as the raw material in this invention; Figure 6 The XRD pattern of the raw material coal gangue for this invention; Figure 7 The XRD pattern of the vanadium-titanium ore slag, the raw material of this invention; Figure 8 The XRD pattern of lithium slag, the raw material for this invention; Figure 9 The XRD pattern of the waste aerated concrete used as a raw material in this invention is shown below. Figure 10 This is a flowchart illustrating the preparation process of autoclaved sand-lime bricks according to the present invention. Figure 11 This is a flowchart illustrating the preparation process of recycled coarse and fine aggregates according to the present invention. Figure 12 This is a flowchart illustrating the preparation process of powder 1 of the present invention; Figure 13 This is a flowchart illustrating the preparation process of powder 2 of the present invention; Figure 14 This is a flowchart illustrating the preparation process of powder 3 of the present invention; Figure 15 This is a flowchart illustrating the preparation process of powder 4 of the present invention; Figure 16 This is a graph showing the effect of fine aggregate content on the mechanical properties of autoclaved sand-lime bricks in Example 2 of the present invention. Figure 17 The XRD pattern of the autoclaved sand-lime brick in Example 2 of this invention; Figure 18 These are SEM images of the autoclaved sand-lime bricks in Examples 2 and 7 of this invention; (a) Fine aggregate content 42%, (b) Fine aggregate content 48%; Figure 19 For the present invention Figure 18 EDS plot of region A in the middle; Figure 20 The images shown are FT-IR images of autoclaved lime-sand bricks in Examples 2 and 7 of this invention. Curve A - Fine aggregate content 42%, Curve B - Fine aggregate content 48%; Figure 21 This is the DSC-TG image of the autoclaved lime-sand brick in Embodiment 2 of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] Unless otherwise specified in the embodiments of the present invention, the techniques or conditions described in the literature in this field or the product instructions shall be followed; if the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased through legitimate channels.

[0045] Raw materials and equipment of the present invention: Eggshell: The main mineral phases are calcite and aragonite, and its main composition is: CaCO3 78~95%, MgCO3 2~9%, Ca3(PO4)2 0.1~3%, SiO2 0.1~3%, Al2O3+CaO+Fe2O3 0.1~3%, loss on ignition 5~15%; Desulfurization ash: The main components and contents are as follows: CaO 55~58%, SO3 35~38%, Cl 1.5~1.8%, F 1.5~1.7%, MgO 1.1~1.3%, SiO2 0.8~1%, Al2O3 0.4~0.5%, Fe2O3 0.2~0.3%, K2O 0.1~0.15%; the main mineral components are: CaSO3 10~20%, CaO 25~40%, CaSO4 43~55%. Coal gangue: The main mineral phases are quartz and clay minerals (kaolinite, illite, montmorillonite and muscovite), siderite, etc. Its main chemical composition and content are: SiO2 40~60%, Al2O3 20~30%, K2O 1~5%, MgO 1~3%, Na2O+K2O 1~4%, Fe2O3 5~15%, CaO 1~5%, loss on ignition 25~40%; Vanadium-titanium ore slag: The main mineral composition is magnesium rhodochrosite and perovskite. The main chemical components and contents are: SiO2 27~33%, CaO 30~35%, Al2O3 8~15%, MgO 8~12%, Fe2O3 5~10%, SO3 0.1~3%, K2O+Na2O 0.1~2%, TiO2 5~10%, and loss on ignition 0.1~3%. Lithium slag: The main mineral components are quartz, spodumene, gypsum, etc., and its chemical composition and content are as follows: CaO 22~30%, SiO2 45~55%, Al2O3 16~22%, SO3 18~23%, Fe2O3 0.1~3%, and others 0.1~3%; Waste aerated concrete: The main mineral composition is quartz, tobermorite, calcite and CSH gel. Its main chemical composition and content are: SiO2 40~60%, Al2O3 3~8%, CaO 20~30%, MgO 1~5%, Fe2O3 1~5%, SO3 1~5%, K2O+Na2O 0.1~2%, loss on ignition 5~15%; Bamboo fiber: Main chemical elements: C 40~50%, H 2~9%, O 42~50%, N 0.1~2%, S 0.01~0.3%, ash 3~10%. Main chemical composition: total cellulose 45~55%, lignin 20~25%, α-cellulose 32~43%.

[0046] Among them, the SEM images of raw materials vanadium-titanium ore slag, lithium slag, waste aerated concrete, and bamboo fiber are as follows: Figures 1-4 As shown; XRD patterns of desulfurization ash, coal gangue, vanadium-titanium slag, lithium slag, and waste aerated concrete are as follows. Figures 5-9 As shown.

[0047] Cone Crusher: Fully hydraulic cone crusher, maximum feed size 85mm, discharge size 8~25mm, processing capacity 109~230t / h, motor power 200kW; Cement ball mill: rotation speed 48 r / min; Jaw crusher: feed size ≤250mm, discharge size ≤10mm; Cement mortar mixer: Rotation speed at low speed: 140±5 r / min (rotation) and 62±5 r / min (revolution); Rotation speed at low speed: 285±10 r / min (rotation) and 125±10 r / min (revolution).

[0048] Example 1 This embodiment provides a sand-lime brick mixture and its preparation method, wherein the sand-lime brick mixture comprises: dry material and bamboo fiber; By weight, the dry material comprises: 26 parts recycled coarse aggregate, 44 parts recycled fine aggregate, 12 parts calcium raw material, 4 parts active raw material, 8 parts fine powder, and 6 parts lightweight material; the bamboo fiber accounts for 2.2 vol.% of the dry material volume.

[0049] like Figure 10 As shown, the preparation method of the lime-sand brick mixture includes the following steps: S1: After mixing recycled coarse aggregate, recycled fine aggregate, calcium raw materials, active raw materials, fine powder and lightweight materials, add 8 parts water and 1.0 vol.% bamboo fiber (by dry volume) and stir at 30 rpm for 8 minutes. Let stand for 1.8 hours to obtain the initial mixture. S2: Add 3 parts water and 1.2 vol.% bamboo fiber (by dry volume) to the initial mixture and stir for 5 minutes to obtain the mixture.

[0050] The mixture is pressed into brick blanks of 240mm×115mm×53mm under a pressure of 16kN. The pressed brick blanks are then sent to an autoclave for high-temperature autoclaving. The process is as follows: sealing, vacuuming, heating (pressurizing), maintaining temperature (pressure), and cooling (pressure reduction). The autoclaving conditions are: autoclaving temperature 180℃, autoclaving pressure 1.3MPa, maintaining temperature (pressure) for 6 hours, cooling and depressurizing for 1.5 hours, and then removing the bricks from the autoclave to obtain autoclaved sand-lime bricks.

[0051] Among them, such as Figure 11 As shown, the method for preparing the recycled coarse aggregate is as follows: (1) Remove the track spikes, bolts and other fixing items from the abandoned railway sleepers; then use an impact drill to crush the abandoned railway sleepers, and sort the steel bars and waste concrete obtained after crushing; then put the waste concrete into a cone crusher to crush it to obtain waste concrete particles with a particle size of 8~16mm and <8mm. (2) Waste concrete particles with a particle size of 8~16mm are placed into a hollow ballless cement ball mill for "stone-on-stone" shaping. After shaping, waste concrete particles with a particle size of 5~12mm and waste concrete particles with a particle size of <5mm are screened out. The waste concrete particles with a particle size of 5~12mm are washed to remove impurities on the surface. The waste concrete particles with a particle size of 5~12mm and the waste concrete particles with a particle size of <5mm after screening are placed in an electric heating drying oven at 105℃ and dried to constant weight to obtain 5~12mm recycled coarse aggregate and washed waste concrete particles with a particle size of <5mm. like Figure 11 As shown, the method for preparing the recycled fine aggregate is as follows: Waste concrete particles with a particle size of <8mm, waste concrete particles with a particle size of <5mm, and waste concrete particles with a particle size of <5mm obtained after washing are mixed evenly and then put into a hollow ballless cement ball mill for "stone-on-stone" shaping. Then, the mixture is screened using a vibrating screen to obtain 0.075~4.75mm recycled fine aggregate and <0.075mm particles for later use. like Figure 12 As shown, the method for preparing the calcium raw material is as follows: (1) Crush the eggshells and rinse them with high pressure water, then place them in a cool place to air dry; place the air-dried eggshell particles in a 105℃ electric heating blast drying oven to dry to constant weight; (2) Remove organic impurities from the desulfurization ash residue by sieving, and then dry it in an electric drying oven at 105℃ for 12 hours before use. (3) The dried eggshells and desulfurized ash were mixed at a mass ratio of 2:1 and then ground in a cement ball mill until the specific surface area was 200 m². 2 / kg; then put the material into a cement mortar mixer and mix for 30s, then add water accounting for 8% of the dry powder mass and mix for 60s; put the mixed material into a mold and press it into pellets with a size of Φ35mm×30mm under a hydraulic press at 18Mpa; place the pellets in an electric heating blast drying oven and dry at 100℃ for 30min; (4) Place the dried pellets into a covered corundum crucible, and then place the crucible in a muffle furnace for high-temperature calcination: raise the temperature from 20°C to 200°C at a rate of 4°C / min, and then hold for 30 min; then raise the temperature from 200°C to the required temperature of 750°C at a rate of 5°C / min, and then hold for 40 min. After calcination, allow the pellets to cool naturally, and then place the cooled pellets into a cement ball mill and grind them to a specific surface area of ​​400 m². 2 / kg, yielding calcium raw material - powder 1; like Figure 13 As shown, the preparation method of the active raw material is as follows: (1) After removing organic impurities from the coal gangue, it is crushed into ≤5mm particles in a jaw crusher; (2) Cut the naturally air-dried wheat straw into 1-5cm pieces and put it into the iron bucket of the combustion furnace. The loose thickness of the wheat straw should be ≤20cm. Cover the top with ≤5cm of coal gangue particles. Alternately stack the wheat straw and coal gangue in a volume ratio of 1:1, repeating 3 times. At the same time, ensure that there is a 10cm gap between the top coal gangue powder and the top of the iron bucket. Then ignite and calcine for 3 hours, then cool. The calcination temperature is 500℃ and the heating rate is 5℃ / min. (3) The cooled calcined material is put into a cement ball mill and ground to 400 μL. 2 / kg, yielding active raw material-powder 2; like Figure 14 As shown, the preparation method of the fine powder is as follows: (1) After removing impurities and organic matter from the vanadium-titanium slag by sieving, the vanadium-titanium slag is placed in a 105℃ electric heating blast drying oven and dried to constant weight for later use. (2) The particles with a diameter <0.075mm generated during the preparation of the recycled fine aggregate are mixed with vanadium-titanium slag at a mass ratio of 1:1; then the mixed material is put into a cement ball mill and ground to 350m. 2 / kg, yielding fine powder - powder 3; like Figure 15 As shown, the preparation method of the lightweight material is as follows: (1) After removing impurities by sieving the lithium slag, place it in a 105℃ electric heating blast drying oven and dry it to constant weight; (2) After removing bricks and organic matter from the waste aerated concrete, cut the large pieces of waste aerated concrete into blocks with a length of less than 20cm, a thickness of less than 5cm, and a width of less than 10cm using a woodworking saw; then put the blocks of waste aerated concrete into a jaw crusher to crush them into 3~5mm particles, and then put the particles into a 105℃ electric heating blast drying oven to dry to constant weight. (3) After mixing the dried lithium slag and waste aerated concrete particles at a mass ratio of 1:2, grind them in a cement ball mill to a powder concentration of 300 μL. 2 / kg, yielding 4 kg of lightweight material-powder; The method for preparing the bamboo fiber: (1) Remove the attached substances from the surface of the waste bamboo poles, rinse them with high pressure water and then air dry them; then cut bamboo pole sections of 150~250mm in length and place them in a 70℃ forced-air drying oven to dry until the moisture content is ≤10%; (2) The bamboo pole section is split into four parts evenly perpendicular to the diameter section; then put into a shredder for crushing, and then sieve to obtain bamboo pole fragments with a diameter of 25~60mm; then put the bamboo pole fragments into a disc mill for disc milling (the disc milling gap is 0.3~0.4mm) to obtain bamboo fibers with a diameter of 30~65um and a length of 5~25mm.

[0052] In Example 1, the physicochemical properties of powder 1 are shown in Table 1, the activity indices of powder 2 and powder 3 are shown in Tables 2 and 3, the radioactivity results of the prepared lime-sand brick mixture are shown in Table 4, and the physical performance indicators and ion leaching results of autoclaved lime-sand bricks are shown in Tables 5 and 6.

[0053] Table 1. Physicochemical properties of powder 1 in Example 1

[0054] *Note: refers to the technical specifications of JC / T 621-2021, "Quicklime for Silicate Building Products".

[0055] Table 2 Activity index of powder 2 in Example 1

[0056] *Note: This refers to the test method in GB / T 17671-2021, "Test Method for Strength of Cement Mortar (ISO Method)".

[0057] Table 3 Activity index of powder 3 in Example 1

[0058] *Note: This refers to the test method in GB / T 17671-2021, "Test Method for Strength of Cement Mortar (ISO Method)".

[0059] Table 4. Radioactivity test results of the lime-sand brick mixture in Example 1

[0060] *Note: These are the test requirements in GB6566-2010, "Limits of Radionuclides in Building Materials".

[0061] Table 5 Technical Specifications of Autoclaved Lime-Sand Bricks in Example 1

[0062] *Note: These are the test requirements in GB / T 11945-2019 "Autoclaved Lime Sand Solid Bricks and Solid Blocks" and JC / T 239-2014 "Autoclaved Fly Ash Bricks".

[0063] Table 6 Ion leaching of autoclaved lime-sand bricks in Example 1 (μg / L)

[0064] *Note: This refers to the requirements of the "Groundwater Quality Standard" GB / T 14848-2017.

[0065] Example 2 This embodiment provides a sand-lime brick mixture and its preparation method, wherein the sand-lime brick mixture comprises: dry material and bamboo fiber; By weight, the dry material comprises: 28 parts recycled coarse aggregate; 42 parts recycled fine aggregate; 13 parts calcium-based raw material; 5 parts active raw material; 8 parts fine powder; 4 parts lightweight material; and bamboo fiber accounts for 2.2 vol.% of the dry material volume. The preparation method of the lime-sand brick mixture includes the following steps: S1: After mixing recycled coarse aggregate, recycled fine aggregate, calcium raw materials, active raw materials, fine powder and lightweight materials, add 10 parts water and 1.2 vol.% bamboo fiber (by dry volume), stir at 30 rpm for 10 min, and let stand for 2.4 h to obtain the initial mixture. S2: Add 2 parts water and 1.0 vol.% bamboo fiber (by dry volume) to the initial mixture and stir for 6 minutes to obtain the mixture.

[0066] The mixture is pressed into brick blanks measuring 240mm × 115mm × 53mm under a pressure of 20kN. The pressed brick blanks are then placed in an autoclave for high-temperature autoclaving. The process involves: sealing, vacuuming, heating (pressurizing), maintaining constant temperature (pressure), and cooling (pressure reduction). The autoclaving conditions are: autoclaving temperature 185℃, autoclaving pressure 1.25MPa, maintaining constant temperature (pressure) for 8 hours, cooling and depressurizing for 2 hours, and then removing the bricks from the autoclave to obtain autoclaved sand-lime bricks.

[0067] The preparation methods of the recycled coarse aggregate and the recycled fine aggregate are the same as in Example 1, and will not be repeated here.

[0068] The method for preparing the calcium raw material is as follows: Steps (1) and (2) are the same as in Example 1, and will not be repeated here; (3) The dried eggshells and desulfurized ash were mixed at a mass ratio of 3:1 and then ground in a cement ball mill until the specific surface area was 250 m². 2 / kg; then put the material into a cement mortar mixer and mix for 40s, then add water accounting for 9% of the dry powder mass and mix for 70s; put the mixed material into a mold and press it into pellets with a size of Φ35mm×30mm under a hydraulic press at 20Mpa; place the pellets in an electric heating blast drying oven and dry at 100℃ for 40min; (4) Place the dried pellets into a covered corundum crucible, and then place the crucible in a muffle furnace for high-temperature calcination: raise the temperature from 20°C to 200°C at a rate of 4°C / min, and then hold for 35 min; then raise the temperature from 200°C to the required temperature of 800°C at a rate of 5°C / min, and then hold for 50 min. After calcination, allow the pellets to cool naturally, and then place the cooled pellets into a cement ball mill and grind them to a specific surface area of ​​450 m². 2 / kg, yielding calcium raw material - powder 1; The preparation method of the active raw material: Step (1) is the same as in Example 1, and will not be repeated here; (2) Cut the naturally air-dried wheat straw into 1-5cm pieces and put it into the iron bucket of the combustion furnace. The loose thickness of the wheat straw should be ≤20cm. Cover the top with ≤5cm of coal gangue particles. Alternately stack the wheat straw and coal gangue in a volume ratio of 1:1, repeating 3 times. At the same time, ensure that there is a 10cm gap between the top coal gangue powder and the top of the iron bucket. Then ignite and calcine for 4 hours, then cool. The calcination temperature is 580℃ and the heating rate is 5℃ / min. (3) The cooled calcined material is put into a cement ball mill and ground to 450 μL. 2 / kg, yielding active raw material-powder 2; The preparation method of the fine powder: Step (1) is the same as in Example 1, and will not be repeated here; (2) The particles with a diameter <0.075mm generated during the preparation of the recycled fine aggregate are mixed with vanadium-titanium slag at a mass ratio of 2:1; then the mixed material is put into a cement ball mill and ground to 400 μL. 2 / kg, yielding fine powder - powder 3; The preparation method of the lightweight material: Steps (1) and (2) are the same as in Example 1, and will not be repeated here; (3) The dried lithium slag and waste aerated concrete particles are mixed at a mass ratio of 1:3 and then ground in a cement ball mill to a powder concentration of 350 μL. 2 / kg, yielding 4 kg of lightweight material-powder; The preparation method of the bamboo fiber is the same as in Example 1, and will not be repeated here.

[0069] In Example 2, the physicochemical properties of powder 1 are shown in Table 7, the activity indices of powder 2 and powder 3 are shown in Tables 8 and 9, the radioactivity results of the lime-sand brick mixture are shown in Table 10, and the physical performance indicators and ion leaching results of autoclaved lime-sand bricks are shown in Tables 11 and 12.

[0070] Table 7 Physicochemical properties of powder 1 in Example 2

[0071] *Note: refers to the technical specifications of JC / T 621-2021, "Quicklime for Silicate Building Products".

[0072] Table 8 Activity index of powder 2 in Example 2

[0073] *Note: This refers to the test method in GB / T 17671-2021, "Test Method for Strength of Cement Mortar (ISO Method)".

[0074] Table 9 Activity index of powder 3 in Example 2

[0075] *Note: This refers to the test method in GB / T 17671-2021, "Test Method for Strength of Cement Mortar (ISO Method)".

[0076] Table 10. Radioactivity test results of the lime-sand brick mixture in Example 2

[0077] *Note: These are the test requirements in GB6566-2010, "Limits of Radionuclides in Building Materials".

[0078] Table 11 Technical Specifications of Autoclaved Lime-Sand Bricks in Example 2

[0079] *Note: These are the test requirements in GB / T 11945-2019 "Autoclaved Lime Sand Solid Bricks and Solid Blocks" and JC / T 239-2014 "Autoclaved Fly Ash Bricks".

[0080] Table 12 Ion leaching of autoclaved lime-sand bricks in Example 2 (μg / L)

[0081] *Note: This refers to the requirements of the "Groundwater Quality Standard" GB / T 14848-2017.

[0082] Example 3 This embodiment provides a sand-lime brick mixture and its preparation method, wherein the sand-lime brick mixture comprises: dry material and bamboo fiber; By weight, the dry material comprises: 25 parts recycled coarse aggregate; 40 parts recycled fine aggregate; 15 parts calcium raw material; 5 parts active raw material; 10 parts fine powder; 5 parts lightweight material; and the bamboo fiber accounts for 2.2 vol.% of the dry material volume. The method for preparing the autoclaved lime-sand bricks includes the following steps: S1: Mix recycled coarse aggregate, recycled fine aggregate, calcium raw material, active raw material, fine powder and lightweight material, add 12 parts water and 1.3 vol.% bamboo fiber (by dry volume), stir at 30 rpm for 12 minutes, let stand for 3 hours to obtain the initial mixture; S2: Add 1 part water and 0.9 vol.% bamboo fiber (dry weight) to the initial mixture and stir for 7 minutes to obtain the mixture.

[0083] The mixture is pressed into brick blanks of 240mm×115mm×53mm under a pressure of 24kN. The pressed brick blanks are then sent to an autoclave for high-temperature autoclaving. The process is as follows: sealing, vacuuming, heating (pressurizing), maintaining temperature (pressure), and cooling (pressure reduction). The autoclaving conditions are: autoclaving temperature 190℃, autoclaving pressure 1.1MPa, maintaining temperature (pressure) for 10 hours, cooling and depressurizing for 3 hours, and then removing the bricks from the autoclave to obtain autoclaved sand-lime bricks.

[0084] The preparation methods of the recycled coarse aggregate and the recycled fine aggregate are the same as in Example 1, and will not be repeated here.

[0085] The method for preparing the calcium raw material is as follows: Steps (1) and (2) are the same as in Example 1, and will not be repeated here; (3) The dried eggshells and desulfurized ash were mixed at a mass ratio of 4:1 and then ground in a cement ball mill until the specific surface area was 300 m². 2 / kg; then put the material into a cement mortar mixer and mix for 50s, then add water accounting for 10% of the dry powder mass and mix for 80s; put the mixed material into a mold and press it into pellets with a size of Φ35mm×30mm under a hydraulic press at 24Mpa; place the pellets in an electric heating blast drying oven and dry at 100℃ for 50min; (4) Place the dried pellets into a covered corundum crucible, and then place the crucible in a muffle furnace for high-temperature calcination: raise the temperature from room temperature to 200℃ at a rate of 4℃ / min, and then hold for 40min; then raise the temperature from 200℃ to the required temperature of 850℃ at a rate of 5℃ / min, and then hold for 60min. After calcination, allow the pellets to cool naturally, and then place the cooled pellets into a cement ball mill and grind them to a specific surface area of ​​500m². 2 / kg, yielding calcium raw material - powder 1; The preparation method of the active raw material: Step (1) is the same as in Example 1, and will not be repeated here; (2) Cut the naturally air-dried wheat straw into 1-5cm pieces and put it into the iron bucket of the combustion furnace. The loose thickness of the wheat straw should be ≤20cm. Cover the top with ≤5cm of coal gangue particles. Alternately stack the wheat straw and coal gangue in a volume ratio of 1:1, repeating 3 times. At the same time, ensure that there is a 10cm gap between the top coal gangue powder and the top of the iron bucket. Then ignite and calcine for 3 hours, then cool. The calcination temperature is 650℃ and the heating rate is 10℃ / min. (3) The cooled calcined material is put into a cement ball mill and ground to 500 μL. 2 / kg, yielding active raw material-powder 2; The preparation method of the fine powder: Step (1) is the same as in Example 1, and will not be repeated here; (2) The particles with a diameter <0.075mm generated during the preparation of the recycled fine aggregate are mixed with vanadium-titanium slag at a mass ratio of 3:1; then the mixed material is put into a cement ball mill and ground to 500 μm. 2 / kg, yielding fine powder - powder 3; The preparation method of the lightweight material: Steps (1) and (2) are the same as in Example 1, and will not be repeated here; (3) The dried lithium slag and waste aerated concrete particles are mixed at a mass ratio of 1:4 and then ground in a cement ball mill to a powder concentration of 400 μL. 2 / kg, yielding 4 kg of lightweight material-powder; The preparation method of the bamboo fiber is the same as in Example 1, and will not be repeated here.

[0086] In Example 3, the physicochemical properties of powder 1 are shown in Table 13, the activity indices of powder 2 and powder 3 are shown in Tables 14 and 15, the radioactivity results of the lime-sand brick mixture are shown in Table 16, and the physical performance indicators and ion leaching results of autoclaved lime-sand bricks are shown in Tables 17 and 18.

[0087] Table 13 Physicochemical properties of powder 1 in Example 3

[0088] *Note: refers to the technical specifications of JC / T 621-2021, "Quicklime for Silicate Building Products".

[0089] Table 14 Activity index of powder 2 in Example 3

[0090] *Note: This refers to the test method in GB / T 17671-2021, "Test Method for Strength of Cement Mortar (ISO Method)".

[0091] Table 15 Activity index of powder 3 in Example 1

[0092] *Note: This refers to the test method in GB / T 17671-2021, "Test Method for Strength of Cement Mortar (ISO Method)".

[0093] Table 16. Radioactivity test results of the lime-sand brick mixture in Example 3

[0094] *Note: These are the test requirements in GB6566-2010, "Limits of Radionuclides in Building Materials".

[0095] Table 17 Technical Specifications of Autoclaved Lime-Sand Bricks in Example 3

[0096] *Note: These are the test requirements in GB / T 11945-2019 "Autoclaved Lime Sand Solid Bricks and Solid Blocks" and JC / T 239-2014 "Autoclaved Fly Ash Bricks".

[0097] Table 18 Ion leaching of autoclaved lime-sand bricks in Example 3 (μg / L)

[0098] *Note: This refers to the requirements of the "Groundwater Quality Standard" GB / T 14848-2017.

[0099] The radioactivity of the lime-sand brick mixture in Examples 1-3 of this invention complies with the provisions of GB6566; the ion leaching of autoclaved lime-sand bricks shows that all eight heavy metal indicators are lower than the standard limits in GB / T 14848-2017 "Groundwater Quality Standard", making them greener, lower carbon, and more environmentally friendly, and meeting the "dual carbon" requirements for building materials advocated by the state.

[0100] Example 4 This embodiment provides a lime-sand brick mixture and its preparation method. The only difference from Embodiment 2 is that the dry material contains 29 parts of recycled coarse aggregate, 40 parts of recycled fine aggregate, and 14 parts of calcium raw material. The dosage and preparation method of other components, as well as the lime-sand brick mixture and its preparation method, are the same as in Embodiment 2, and will not be repeated here.

[0101] Example 5 This embodiment provides a lime-sand brick mixture and its preparation method. The only difference from Embodiment 2 is that the dry material contains 24 parts of recycled coarse aggregate, 44 parts of recycled fine aggregate, and 15 parts of calcium raw material. The dosage and preparation method of other components, as well as the preparation methods of the lime-sand brick mixture and autoclaved lime-sand bricks, are the same as in Embodiment 2, and will not be repeated here.

[0102] Example 6 This embodiment provides a lime-sand brick mixture and its preparation method. The only difference from Embodiment 2 is that the dry material contains 25 parts of recycled coarse aggregate, 46 parts of recycled fine aggregate, and 12 parts of calcium raw material. The dosage and preparation method of other components, as well as the preparation methods of the lime-sand brick mixture and autoclaved lime-sand bricks, are the same as in Embodiment 2, and will not be repeated here.

[0103] Example 7 This embodiment provides a lime-sand brick mixture and its preparation method. The only difference from Embodiment 2 is that the dry material contains 24 parts of recycled coarse aggregate, 48 parts of recycled fine aggregate, and 11 parts of calcium raw material. The dosage and preparation method of other components, as well as the preparation methods of the lime-sand brick mixture and autoclaved lime-sand bricks, are the same as in Embodiment 2, and will not be repeated here.

[0104] Example 8 This embodiment provides a lime-sand brick mixture and its preparation method. The only difference from Embodiment 2 is that the dry material contains 23 parts of recycled coarse aggregate, 50 parts of recycled fine aggregate, and 10 parts of calcium raw material. The dosage and preparation method of other components, as well as the preparation methods of the lime-sand brick mixture and autoclaved lime-sand bricks, are the same as in Embodiment 2, and will not be repeated here.

[0105] Performance and structure of autoclaved sand-lime bricks (1) Mechanical properties of autoclaved lime-sand bricks Figure 16 The effect of fine aggregate content on the mechanical properties of autoclaved sand-lime bricks is shown in Examples 2 and 4-8. The fine aggregate content in the figures is 40%, 42%, 44%, 46%, 48%, and 50%, respectively. The content of powder 2, powder 3, and powder 4 is fixed at 5%, 8%, and 4%, respectively. The bamboo fiber content is 2.2 vol.% by volume. The mix design of the sand-lime brick mixture is shown in Table 19. The autoclaving conditions are: autoclaving temperature 185℃, autoclaving pressure 1.25 MPa, constant temperature (constant pressure) for 8 hours, and cooling and depressurization for 2 hours.

[0106] Table 19 Mix Proportion of Lime-Sand Brick Mixture

[0107] Depend on Figure 16 It can be seen that with the increase of recycled fine aggregate content, the compressive strength and flexural strength of autoclaved aerated concrete (AAC) bricks show a trend of first increasing and then decreasing. When the fine aggregate content increases from 40% to 42%, the compressive strength of AAC bricks increases from 33.92 MPa to 35.93 MPa, an increase of 5.93%; simultaneously, the flexural strength also increases from 7.12 MPa to 8.24 MPa, an increase of 15.73%. When the recycled fine aggregate content increases from 42% to 50%, the compressive strength of the products gradually decreases, from 35.93 MPa to 25.46 MPa. When the fine aggregate content increases from 40% to 46%, the compressive strength of the products is greater than 30 MPa, meeting the requirements of MU30 in GB / T 11945-2019 "Autoclaved Aerated Concrete Solid Bricks and Blocks" and JC / T 239-2014 "Autoclaved Fly Ash Bricks". When the recycled fine aggregate increased from 42% to 50%, the flexural strength of the product gradually decreased, from 8.24 MPa to 6.26 MPa. However, due to the addition of bamboo fiber to the product, the tensile strength of the autoclaved fly ash brick product met the requirement of ≥4.8 MPa for MU30 grade fly ash bricks in JC / T 239-2014 "Autoclaved Fly Ash Bricks".

[0108] (2) Mineral composition and structure of autoclaved lime-sand bricks ①XRD analysis First, XRD was used to perform diffraction analysis on the sample. Then, the obtained data was analyzed using Jade software and compared with the XRD chart. Finally, Origin software was used to plot the data, label the main diffraction peaks, and analyze the phase composition. Figure 17 XRD patterns of autoclaved sand-lime brick samples from Example 2 are presented. The figures show that the mineral composition of the sand-lime brick mixture after high-temperature curing is: tobeimorite, hydrogarnet, anhydrite, calcite, quartz, and albite. Through hydrothermal reaction, the sand-lime brick mixture, rich in active silica (alumina) and calcareous materials, reacts to form autoclaved products. The main components are hydrated calcium silicate and tobeimorite, which determine the performance of the autoclaved products. The formation and diffusion of these mineral phases bind the aggregates together, resulting in a dense structure with few pores, forming a high-strength whole. Tobeimorite possesses excellent mechanical properties, enhancing the mechanical properties of the autoclaved sand-lime bricks made from solid waste. Furthermore, Figure 17The presence of a distinct "bun peak" at 25-35° indicates the formation of low-crystallinity amorphous substances and CSH gel within the autoclaved lime-sand brick.

[0109] ②SEM-EDS analysis Figure 18 (a) and Figure 18 (b) SEM images of autoclaved sand-lime bricks from Example 2 (42% recycled fine aggregate) and Example 7 (48% recycled fine aggregate) are presented respectively. Figure 18 In Example 2 of (a), it is clearly visible that the cross-section of the autoclaved lime-sand brick product under autoclaving conditions shows that the hydration products of needle-like tobermorite interact and overlap to form a new network structure, which ensures the strength of the autoclaved lime-sand brick. This also proves that the mechanical properties of the autoclaved lime-sand brick product sample of Example 2 are relatively high. In Example 7, the tobermorite in the autoclaved lime-sand brick product sample is mostly leaf-shaped, and at the same time... Figure 18 (b) shows the presence of a small amount of poorly crystallized, gel-like CSH gel.

[0110] Electron diffraction (EDS) analysis of autoclaved hydration products can determine their chemical composition and mineral types. Figure 19 for Figure 18 (a) EDs map of region A within the box. From Figure 19 As can be seen from the data, Al is present in the autoclaved hydration products. This is mainly due to the presence of Al in the raw material system, which causes some [SiO4] tetrahedra to be replaced by [AlO4] tetrahedra. The nCa / n(Si+Al) ratio of the autoclaved hydration products in region A is 0.825, which is similar to that of tobermorite (Ca5(OH)2Si6O). 16 The composition of ∙4H2O with nCa / n(Si) = 0.833 is basically consistent.

[0111] ③FT-IR analysis Figure 20 FT-IR spectra of autoclaved sand-lime bricks from Example 2 (42% recycled fine aggregate) and Example 7 (48% recycled fine aggregate) are presented respectively. As can be seen from the figures, the FT-IR spectra of the autoclaved sand-lime bricks from Examples 2 and 7 are not significantly different. The wavenumber in the figures is 1440 cm⁻¹. -1 The spectral band is CO3 2- The characteristic spectral band has a wavenumber of 3480 cm⁻¹. -1 1640cm -1 ~1650cm -1 The asymmetric stretching and bending vibrations of the -Si-OH hydroxyl groups in the spectral hydrates, and the variations in their band positions, indicate differences in the amount of bound water in the surface products. The characteristic spectral line of tobermorite appears at 974 cm⁻¹. -1This is an asymmetric stretching vibration of the -Si-O bond during hydration.

[0112] ④ DSC-TG analysis Figure 21 Thermogravimetric analysis (TGA) curves of autoclaved lime-sand bricks from Example 2 (containing 42% recycled fine aggregate) are presented. The graph shows a broad and flat endothermic peak between 70 and 200 °C, primarily indicating the removal of free water, adsorbed water, and weak crystal water from certain hydration products. Singh et al. suggest that the dehydration decomposition temperature of CSH gel is in the range of 120–140 °C. Liu et al. point out that this endothermic peak is mainly due to the high alkalinity and poor crystallinity of the hydration products, which are essentially colloidal substances. Figure 21 Endothermic peaks appeared at 107℃, 463℃, 577℃, and 762℃ on the DSC curve. The endothermic peak at 107℃ was relatively sharp, accompanied by a weight loss of 4.38%. Combined with XRD and SEM analysis results, it can be seen that the endothermic peak at this point was formed by the dehydration of CSH gel. Further heating resulted in a large endothermic peak at 463℃, mainly caused by the loss of structural water from tobermorite and hydrogarnet in the sand-lime brick mixture. The endothermic peak at 577℃ was formed by the crystal transformation of quartz in the raw material, mainly the transformation from β-quartz to α-quartz. At this point, no significant weight loss was observed on the TG curve. The endothermic peak at 762℃ was caused by the loss of structural water from the CSH gel. Simultaneously, the endothermic peak from calcite decomposition also occurred near this temperature. Therefore, the resulting endothermic peak was relatively large.

[0113] In summary, this invention utilizes a mixture of waste railway sleepers, vanadium-titanium slag, coal gangue, and waste aerated concrete to prepare autoclaved sand-lime bricks. The resulting bricks exhibit improved mechanical properties (strength), physical properties (water absorption rate, softening coefficient), and frost resistance, surpassing existing market products and thus warranting widespread promotion.

[0114] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An autoclaved sand-lime brick containing lithium battery-coal-steel-construction solid waste, characterized in that, The mixture of autoclaved lime-sand bricks includes dry materials and bamboo fiber; By weight, the dry material comprises: 23-35 parts recycled coarse aggregate; 40-53 parts recycled fine aggregate; 10-16 parts calcium raw material; 3-7 parts active raw material; 7-12 parts fine powder; and 4-8 parts lightweight material. The bamboo fiber accounts for 1.8~2.6 vol.% of the dry material volume. The recycled coarse aggregate is waste concrete particles with a particle size of 5~12mm; The recycled fine aggregate is waste concrete particles with a particle size of 0.075~4.75mm; The specific surface area of ​​the calcium-based raw material is 400~500 m². 2 / kg; the specific surface area of ​​the active raw material is 400~500m². 2 / kg; the specific surface area of ​​the fine powder is 350~450m². 2 / kg; the specific surface area of ​​the lightweight material is 300~400m². 2 / kg.

2. The autoclaved lime-sand brick containing lithium battery-coal-steel-construction solid waste according to claim 1, characterized in that, The method for preparing the calcium raw material includes the following steps: B1 pressing molding: Eggshells and desulfurization ash are mixed and ground to a specific surface area of ​​200~300m². 2 / kg, add water and stir, put into a mold, press into pellets and dry; B2 High-Temperature Calcination: The pellets are calcined at high temperature and then cooled to room temperature to obtain the high-temperature calcined product; the high-temperature calcined product is then ground to a specific surface area of ​​400~500 m². 2 / kg.

3. The autoclaved lime-sand brick containing lithium battery-coal-steel-construction solid waste according to claim 2, characterized in that, The mass ratio of the eggshell to the desulfurization ash is 2-4:1; the mass of the water is 8-10% of the total mass of the dry eggshell and desulfurization ash.

4. The autoclaved lime-sand brick containing lithium battery-coal-steel-construction solid waste according to claim 2 or 3, characterized in that, The high-temperature calcination procedure is as follows: the temperature is raised from 20°C to 200°C at a rate of 4°C / min, and held for 30-40 minutes; then the temperature is raised from 200°C to the required temperature of 750-850°C at a rate of 5°C / min, and held for 40-60 minutes.

5. The autoclaved lime-sand brick containing lithium battery-coal-steel-construction solid waste according to claim 1, characterized in that, The preparation method of the active raw material is as follows: Wheat straw is covered with coal gangue particles on top, and the wheat straw and coal gangue are alternately stacked at a volume ratio of 1:1, repeated 2-3 times, followed by calcination. The cooled calcined material is then ground to a specific surface area of ​​400-500 m². 2 / kg; And / or, the calcination temperature is 450~650℃, the heating rate is 5~10℃ / min, and the calcination time is 3~5h.

6. The autoclaved lime-sand brick containing lithium battery-coal-steel-construction solid waste according to any one of claims 1-3, characterized in that, The fine powder consists of waste concrete particles with a particle size of <0.075mm and vanadium-titanium slag in a mass ratio of 1 to 3:

1.

7. The autoclaved lime-sand brick containing lithium battery-coal-steel-construction solid waste according to any one of claims 1-3, characterized in that, The lightweight material is a granular mixture of lithium slag and waste aerated concrete particles in a mass ratio of 1:2 to 4.

8. The autoclaved lime-sand brick containing lithium battery-coal-steel-construction solid waste according to any one of claims 1-3, characterized in that, The diameter and length of the bamboo fiber are 30~65um and 5~25mm, respectively.

9. A method for preparing autoclaved aerated concrete bricks containing lithium battery-coal-steel-construction solid waste as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1: Mix recycled coarse aggregate, recycled fine aggregate, calcareous raw materials, active raw materials, fine powder and lightweight materials, add 8-13 parts water and 0.9-1.3 vol.% bamboo fiber (by dry volume), stir at 25-35 rpm for 8-13 minutes, and let stand for 1.5-3 hours to obtain the initial mixture. S2: Add 1-3 parts water and 0.9-1.3 vol.% bamboo fiber (by dry volume) to the initial mixture and stir for 5-7 minutes to obtain the mixture; S3: Press the mixture into shape and steam-cur it.

10. The method for preparing autoclaved lime-sand bricks containing lithium battery-coal-steel-construction solid waste according to claim 9, characterized in that, The pressing pressure is 16~24kN; the autoclaving temperature is 170~195℃, the pressure is 1.1~1.3MPa, the constant temperature and pressure time is 6~10h, and the cooling and depressurization time is 1~3h.

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