Aerated concrete block and preparation method thereof

Abstract

The invention provides an aerated concrete block and a preparation method thereof. The aerated concrete block is prepared from the following raw materials in percentage by weight: 58 to 74 percent of fly ash aluminum extraction residues, 2 to 3 percent of gypsum, 7 to 14 percent of cement, 16 to 29 percent of quick lime and 0.05 to 0.08 percent of aluminum powder paste. The characteristics of the fly ash aluminum extraction residues are fully utilized, and the fly ash aluminum extraction residues are cooperated with other raw material components with specific contents, so that the obtained aerated concrete block is high in compressive strength, small in dry density, low in cost, excellent in comprehensive performance and suitable for wide popularization and utilization.

Description

Technical Field

[0001] The invention relates to the technical field of the construction industry, and in particular to an aerated concrete building block and a preparation method thereof. Background Art

[0002] Aerated concrete blocks are light in weight, with a density range of 500-1000kg / m 3 When used as a filling wall, it can significantly reduce the weight of the main building, and has excellent thermal insulation performance and low thermal conductivity, generally 0.16-0.20W / (m·K). Due to its high comprehensive performance, convenient construction and superior economy, aerated concrete blocks are the main substitute for clay bricks. They are the non-load-bearing component materials for assembled building exterior walls, partition walls, etc. promoted by the country. As a green building wall material, they are widely used in construction projects.

[0003] In the existing technology, the output of fly ash will cause serious environmental pollution. In order to comprehensively utilize a large amount of fly ash and based on the characteristics of fly ash produced after coal combustion, the latest new process for producing alumina from fly ash is that 1 ton of alumina can be extracted for every 2.5 tons of fly ash, and 1.5 tons of fly ash aluminum extraction residue will be produced. The accumulation of a large amount of solid waste will lead to waste of resources and pollute the environment.

[0004] Patent ZL202210950525.6 discloses a method for preparing aerated concrete blocks from tungsten-nickel ore tailings powder and fly ash aluminum extraction residue, wherein fly ash aluminum extraction residue slurry is 50-60%, tungsten-nickel ore tailings powder is 10-20%, quicklime is 18-25%, cement is 8-12%, aluminum powder paste is 0.08-0.1%, and desulfurized gypsum is 1-3%. The prepared aerated concrete blocks have a compressive strength of ≥3.60MPa and a volume density of ≤598kg / m 3 However, the proportion of fly ash aluminum extraction residue in the raw materials is small, the waste residue is not fully utilized, and the compressive strength of the prepared aerated concrete blocks is still low and the density is still high. Summary of the invention

[0005] The main purpose of the present invention is to provide an aerated concrete block and a preparation method thereof, so as to solve the problems in the prior art that fly ash aluminum extraction residue pollutes the environment, cannot be fully utilized, and the aerated concrete block has poor performance.

[0006] In order to achieve the above object, according to one aspect of the present invention, an aerated concrete block is provided. The raw materials of the aerated concrete block include 58-74% fly ash aluminum extraction residue, 2-3% gypsum, 7-14% cement, 16-29% quicklime and 0.05-0.08% aluminum powder paste.

[0007] Furthermore, the fly ash aluminum extraction residue includes a fluidized bed fly ash acid method aluminum extraction residue; preferably, the fly ash aluminum extraction residue has a specific surface area of ​​60 to 100 m 2 / g, particle size D90≤75μm; and / or, the true density of fly ash aluminum extraction residue is 1.3-2.35g / cm 3 , bulk density is 0.3~0.6g / cm 3 .

[0008] Further, the gypsum includes power plant desulfurization gypsum; preferably, the moisture content of the gypsum is ≤16% by weight, and the content of high-grade CaSO4·2H2O is ≥85%; and / or, the cement includes one or more of 425 cement, 325 cement and 525 cement; and / or, the quicklime includes 90 quicklime; preferably, the content of effective CaO in the quicklime is ≥85%, the content of MgCO3 is ≤12%, and the particle size is 40-75μm by weight; and / or, the aluminum powder paste includes GLS-65 water-based paste; preferably, the effective Al in the aluminum powder paste is ≥90% by weight, and the particle size is ≤75μm.

[0009] According to another aspect of the present invention, a method for preparing the above-mentioned aerated concrete blocks is provided, comprising the following steps: step S1, drying and crushing the fly ash aluminum extraction residue in sequence to obtain a first dry material; step S2, adding gypsum to the first dry material and performing a first stirring; then adding cement and quicklime and performing a second stirring to obtain a second dry material; step S3, adding a first portion of water to the second dry material and performing a third stirring to obtain a first slurry; step S4, mixing the aluminum powder paste with the second portion of water, and then adding the mixture to the first slurry, and adding the third portion of water, and performing water washing and a fourth stirring in sequence to obtain a second slurry; step S5, pouring and stopping the second slurry in sequence to obtain a wet blank; step S6, steam curing the wet blank to obtain an aerated concrete block.

[0010] Furthermore, in step S1, the drying temperature is 90-130° C. and the drying time is 40-60 hours.

[0011] Furthermore, in step S2, the rotation speed of the first stirring is 285±10r / min, the revolution speed is 125±10r / min, and the time is 50-70s; and / or, the rotation speed of the second stirring is 140±5r / min, the revolution speed is 62±5r / min, and the time is 210-270s.

[0012] Further, in step S3, the weight ratio of the first part of water to the second dry material is (70-73):100; and / or the addition temperature of the first part of water is 32-38°C; and / or the third stirring includes a third pre-stirring and a third post-stirring performed sequentially, the third pre-stirring is stirred for 15-25s at a rotation speed of 285±10r / min and a revolution speed of 125±10r / min, and the third post-stirring is stirred for 200-240s at a rotation speed of 140±5r / min and a revolution speed of 62±5r / min.

[0013] Further, in step S4, the weight ratio of the second part of water to the second dry material is (3-3.75):100, and the weight ratio of the third part of water to the second dry material is (9-11.25):100; and / or, the fourth stirring includes a fourth front stirring and a fourth rear stirring performed in sequence, the fourth front stirring is stirred at a rotation speed of 285±10r / min and a revolution speed of 125±10r / min for 6-10s, and the fourth rear stirring is stirred at a rotation speed of 140±5r / min and a revolution speed of 62±5r / min for 35-45s.

[0014] Furthermore, in step S5, the temperature of the static state is 40-50° C., and the time is 130-170 min.

[0015] Furthermore, in step S6, steam curing includes: keeping the wet blank in a steam environment at 55-65° C. for 25-35 minutes, then keeping it in a steam environment at 60-80° C. for 5-7 days, and finally keeping it in a drying condition at 40-50° C. for 4-6 days.

[0016] By applying the technical solution of the present invention, the fly ash aluminum extraction residue has a porous structure and a large specific surface area. When used as a component of aerated concrete blocks, it can effectively improve the utilization rate of industrial waste residues, increase the amount of waste used, reduce environmental pollution, and save costs. At the same time, the fly ash aluminum extraction residue mainly consists of silicon dioxide and aluminum oxide, which are easy to cooperate with the cement, quicklime, gypsum, and aluminum powder paste of the present invention, can well reduce the dry density of the blocks, and can significantly improve the mechanical strength of the aerated concrete blocks. The present invention makes full use of the characteristics of the fly ash aluminum extraction residue, and cooperates with other raw material components with specific contents, so that the obtained aerated concrete blocks have high compressive strength, low dry density, low cost, excellent performance, and are suitable for wide promotion and utilization. DETAILED DESCRIPTION

[0017] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments and comparative examples. In addition, unless otherwise specified, the percentage content of each component in the present application is measured by weight percentage content.

[0018] As described in the background of the present invention, the prior art has the problems that the fly ash aluminum extraction residue pollutes the environment, cannot be fully utilized, and the aerated concrete block has poor performance. In order to solve the above problems, in a typical embodiment of the present invention, an aerated concrete block is provided. The raw materials of the aerated concrete block include 58-74% of fly ash aluminum extraction residue, 2-3% of gypsum, 7-14% of cement, 16-29% of quicklime and 0.05-0.08% of aluminum powder paste by weight percentage.

[0019] The inventor unexpectedly found during the research that the fly ash aluminum extraction residue has a fine particle size, a large specific surface area, and a colloidal nature. This application specifically uses fly ash aluminum extraction residue as a filler for aerated concrete blocks. The fly ash aluminum extraction residue has a porous structure and a large specific surface area. The silicon dioxide and aluminum oxide account for a large proportion of the components, and the density is small, which is conducive to reducing the density of the aerated concrete blocks. In addition, the fly ash aluminum extraction residue can be coordinated with cement, quicklime, gypsum, and aluminum powder paste to effectively reduce the dry density of the blocks, improve the compressive strength of the aerated concrete blocks, and thus improve the quality of the project. However, if the content of fly ash aluminum extraction residue is too high, the compressive strength of the aerated concrete blocks may be too low, which is not convenient for practical use. If its content is too low, the amount of solid waste added is small, and the full utilization of solid waste cannot be achieved. Therefore, this application specifically limits the content of fly ash aluminum extraction residue to 58-74%.

[0020] Gypsum has the characteristics of fast setting and hardening, stable size, high porosity and good fire resistance. When used as a raw material for the blocks of this application, it can promote the hardening of concrete and improve the strength and crack resistance of the blocks. However, if the gypsum content is too high, it may cause the setting time of the aerated concrete blocks to be too long and the production efficiency to be low. If the gypsum content is too low, it may cause the hydration reaction time of the aerated concrete blocks to be too short, which is easy to affect the strength of the aerated concrete blocks. Therefore, this application specifically limits the gypsum content to 2-3%.

[0021] The hydration, coagulation and hardening reaction of cement can improve the strength and durability of the blocks. However, if the cement content is too high, it may lead to increased production costs and low economic benefits. If the cement content is too low, the compressive strength of the aerated concrete blocks may be too low. Therefore, the present application specifically limits the cement content to 7-14%. Under this condition, the cost of the aerated concrete blocks is low and the compressive strength is qualified.

[0022] Quicklime contains effective calcium oxide, which can further increase the strength of the blocks. However, if the content of quicklime is too high, it may increase the production cost of the aerated concrete blocks, and if the content is too low, it may lead to low compressive strength of the aerated concrete blocks. Therefore, the present application specifically limits the content of quicklime to 16-29%.

[0023] As a gas-generating agent, aluminum powder paste can construct a pore structure inside the block and reduce the dry density of the block. However, if the content of aluminum powder paste is too high, it may cause uneven distribution of bubbles inside the aerated concrete block, affecting the uniformity of the block. If the content is too low, it may cause the density of the block to be too high. Therefore, this application specifically limits the content of aluminum powder paste to 0.05-0.08%.

[0024] The above-mentioned specific contents of the raw material components work together to effectively improve the strength of the blocks and reduce the dry density of the blocks. The aerated concrete blocks of the present application use fly ash aluminum residue as the main raw material, which can consume a large amount of fly ash aluminum residue, realize the resource utilization of industrial solid waste, reduce environmental pollution, and the obtained aerated concrete blocks can be used in the construction field, with good economic and social benefits.

[0025] In a preferred embodiment, the fly ash aluminum extraction residue includes a fluidized bed fly ash acid extraction aluminum residue, which can be the residue remaining after the fluidized bed fly ash is corroded with hydrochloric acid to extract aluminum oxide; the addition of the above-mentioned type of residue is more conducive to improving the compressive strength of aerated concrete blocks and improving the quality of the project. Preferably, the specific surface area of ​​the fly ash aluminum extraction residue is 60 to 100 m 2 / g, particle size D90 ≤ 75 μm, and / or, true density 1.3 to 2.35 g / cm 3 , bulk density is 0.3~0.6g / cm 3 Under the above conditions, the fly ash aluminum extraction residue has a smaller particle size and a smaller dry density, which can further effectively reduce the density of aerated concrete blocks.

[0026] In a preferred embodiment, the gypsum includes desulfurization gypsum from a power plant, which can further utilize industrial waste and is more conducive to resource rationalization. In order to further improve the purity of the gypsum and further improve the strength of the building block, preferably, the water content of the gypsum is ≤16% by weight, and the content of CaSO4·2H2O in the gypsum is ≥85%.

[0027] To further reduce production costs, in a preferred embodiment, the cement is one or more of 425 cement, 325 cement and 525 cement; preferably, the cement is 425 cement, which contains, by weight percentage, 28-30% SiO2, 12.5-14.5% Al2O3, 3.5-4.5% Fe2O3, 44-46% CaO, 1.5-1.6% MgO, 0.5-0.6% K2O, 0.01-0.21% Na2O, 0.01-0.08% P2O5, 2.2-2.3% SO3, 0.15-0.25% MnO, 0.4-0.6% TiO2, 0.01-0.02% V2O5 and 3.3-3.5% LOI; LOI refers to loss on ignition.

[0028] For the purpose of improving the compressive strength of the product, in a preferred embodiment, the quicklime includes 90% quicklime. To further provide sufficient calcium element, preferably, by weight percentage, the effective CaO content in the quicklime is ≥85%, the MgCO3 content is ≤12%, and the particle size is 40-75 μm.

[0029] In order to make the concrete block have a more suitable lightweight porous structure, thereby making it more homogeneous and further reducing its dry density, in a preferred embodiment, the aluminum powder paste includes GLS-65 water-based paste; based on similar reasons, it is further preferred that, by weight percentage, the effective Al in the aluminum powder paste is ≥ 90%, and the particle size is ≤ 75 μm. Wherein, "effective Al" refers to the effective active aluminum in the aluminum powder paste.

[0030] As mentioned above, when fly ash aluminum extraction residue is used as a component of aerated concrete blocks, it not only improves the utilization rate of fly ash aluminum extraction residue and reduces environmental pollution, but also the fly ash aluminum extraction residue can cooperate with other components of aerated concrete blocks to effectively improve the compressive strength of aerated concrete blocks and reduce their dry density. In a preferred embodiment, the compressive strength of aerated concrete blocks is ≥3.5MPa and the dry density is ≤650Kg / m 3 .

[0031] In another typical embodiment of the present invention, a method for preparing the above-mentioned aerated concrete blocks is also provided, comprising the following steps: step S1, drying and crushing the fly ash aluminum extraction residue in sequence to obtain a first dry material; step S2, adding gypsum to the first dry material and performing a first stirring; then adding cement and quicklime and performing a second stirring to obtain a second dry material; step S3, adding a first portion of water to the second dry material and performing a third stirring to obtain a first slurry; step S4, mixing the aluminum powder paste with the second portion of water, and then adding the mixture to the first slurry, and adding the third portion of water, and performing water washing and a fourth stirring in sequence to obtain a second slurry; step S5, pouring and stopping the second slurry in sequence to obtain a wet blank; step S6, steam curing the wet blank to obtain an aerated concrete block.

[0032] The present invention firstly stirs and mixes fly ash aluminum extraction residue, gypsum, cement and quicklime, then adds water and stirs, and quicklime reacts with active silicon dioxide and aluminum oxide in fly ash aluminum extraction residue in the presence of water to generate crystalline or colloidal hydrated calcium silicate and calcium aluminosilicate products, and provides an effective heat source at the same time, so that the wet blank can be hardened to obtain basic strength. Gypsum can dissolve quicklime and slow down the thickening speed of slurry. The hydration, coagulation and hardening of cement can improve the strength of the building block, and can provide calcium hydroxide to react with the silicon and aluminum components in the fly ash aluminum extraction residue, thereby improving the strength and durability of the building block. Subsequently, aluminum powder paste mixed with water is added thereto, and the aluminum powder paste reacts with water to generate hydrogen and aluminum hydroxide, and reacts with gypsum to generate calcium sulfoaluminate. Then, pouring and static stopping are performed to obtain the wet blank. During the static stopping period, a good pore structure can be formed inside the building block. Finally, the wet blank is steam cured to maintain the humidity of the concrete surface, prevent premature evaporation of water, and provide a constant temperature to allow the cement hydration process to proceed normally and improve the strength of the concrete.

[0033] The preparation method is simple, easy to operate, and has reasonable processing steps. It is more suitable for the preparation of aerated concrete blocks of specific components of the present invention and has stronger practicality. During the preparation process, the principle that effective calcium reacts with silicon dioxide under steam to form a calcium silicate gel material and the characteristic that aluminum powder paste chemically reacts to generate hydrogen are utilized, so that the prepared aerated concrete blocks have excellent characteristics of light weight and high strength.

[0034] In order to further improve the degree of crushing of the raw materials and to allow the fly ash aluminum-extracting residue to fully contact and react with other components as much as possible during the mixing process, in a preferred embodiment, in step S1, the drying temperature is 90-130°C and the time is 40-60h; the crushing is carried out using a micro-crusher.

[0035] In a preferred embodiment, in step S2, the first stirring has a rotation speed of 285±10 r / min, a revolution speed of 125±10 r / min, and a time of 50 to 70 s; the second stirring has a rotation speed of 140±5 r / min, a revolution speed of 62±5 r / min, and a time of 210 to 270 s. Under the above conditions, the materials are mixed more evenly, which is more conducive to the subsequent reaction.

[0036] In a preferred embodiment, in step S3, the weight ratio of the first part of water to the second dry material is (70-73):100; and / or, the temperature of adding the first part of water is 32-38° C. Under the above conditions, the addition of water provides solution conditions for the reaction, making the reaction more complete. In addition, adding the above water as one of the raw materials to participate in each reaction is conducive to obtaining a more homogeneous and stronger building block.

[0037] In order to further fully disperse the components in the slurry, in a preferred embodiment, in step S3, the third stirring includes a third pre-stirring and a third post-stirring performed in sequence, the third pre-stirring is stirred at a rotation speed of 285±10r / min and a revolution speed of 125±10r / min for 15-25s, and the third post-stirring is stirred at a rotation speed of 140±5r / min and a revolution speed of 62±5r / min for 200-240s. Under the above conditions, the material can be dispersed more quickly.

[0038] In order to make the aluminum powder paste contact with other components more fully to prepare a more uniform aerated concrete block, in a preferred embodiment, in step S4, the weight ratio of the second part of water to the second dry material is (3-3.75):100, and the weight ratio of the third part of water to the second dry material is (9-11.25):100. Under the above conditions, it is more conducive to the full contact between water and aluminum powder. In a preferred embodiment, the fourth stirring includes the fourth front stirring and the fourth rear stirring performed in sequence, the fourth front stirring is stirred at a rotation speed of 285±10r / min and a revolution speed of 125±10r / min for 6-10s, and the fourth rear stirring is stirred at a rotation speed of 140±5r / min and a revolution speed of 62±5r / min for 35-45s. Under the above conditions, the contact between aluminum powder and water and other components can be further promoted, which is more conducive to the uniform distribution of pores inside the block.

[0039] In a preferred embodiment, in step S5, the temperature of the static state is 40-50°C and the time is 130-170 minutes. Under the above conditions, the slurry can be more fully solidified and easier to shape, and it can also be easier to cut and subsequently process.

[0040] In order to more fully carry out the hydration process of cement, lime and fly ash residue to achieve higher demoulding strength, in a preferred embodiment, in step S6, steam curing includes: keeping the wet blank in a steam environment of 55-65°C for 25-35 minutes, then keeping it in a steam environment of 60-80°C for 5-7 days, and finally stopping it for 4-6 days under a drying condition of 40-50°C. Among them, keeping the wet blank in a steam environment of 55-65°C for 25-35 minutes is more conducive to the formation of preliminary hydration products, then keeping it in a steam environment of 60-80°C for 5-7 days, which is more conducive to the formation of hydrated calcium silicate gel, and finally stopping it for 4-6 days under a drying condition of 40-50°C, which is more conducive to the formation of steam-cured aerated concrete blocks.

[0041] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0042] Example 1

[0043] The fly ash aluminum extraction residue is the residue left after the fluidized bed fly ash is etched with hydrochloric acid to extract aluminum oxide. The chemical composition is shown in Table 1 below:

[0044] Table 1

[0045] Element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO CaO <![CDATA[TFe2O3]]> <![CDATA[Na2O]]> <![CDATA[K2O]]> <![CDATA[TiO2]]> LOI wt% 55.84 23.01 0.03 0.30 0.74 2.99 0.34 4.17 12.54

[0046] The specific surface area of ​​the fly ash aluminum residue is 72m 2 / g, particle size D90≤75μm; the average true density is 1.9g / cm 3 , bulk density is 0.4g / cm 3 ;

[0047] The gypsum is desulfurization gypsum from a power plant; in terms of weight percentage, the moisture content of the gypsum is 15%, and the content of CaSO4·2H2O is 86%;

[0048] The cement is commercially available 425 cement, and the cement composition is shown in Table 2 below:

[0049] Table 2

[0050]

[0051] The quicklime is commercially available 90 quicklime, wherein, by weight percentage, the effective CaO content is ≥85%, the MgCO3 content is ≤12%, and the particle size is 40-75 μm;

[0052] The aluminum powder paste is GLS-65 water-based paste, the effective Al in the aluminum powder paste is ≥90%, and the particle size is ≤75μm.

[0053] The specific composition of aerated concrete blocks is shown in Table 3. The preparation method is as follows:

[0054] Step S1, drying the fly ash aluminum extraction residue at 110° C. for 48 hours, crushing it with a micro-crusher, and setting it aside.

[0055] Step S2, weighing in proportion, mixing the fly ash acid method aluminum extraction residue with the power plant desulfurization gypsum first to obtain the first dry material, stirring at a rotation speed of 285 rpm and a revolution speed of 125 rpm for 1 min; then adding cement and quicklime powder, stirring at a rotation speed of 140 rpm and a revolution speed of 62 rpm for 4 min, and mixing to obtain the second dry material.

[0056] Step S3, weigh 35°C tap water according to the weight ratio of the first part of water / the second dry material = 0.72, add the water to the second dry material, first stir at a rotation speed of 285rpm and a revolution speed of 125rpm for 20s, and then stir at a rotation speed of 140rpm and a revolution speed of 62rpm for 220s to obtain a first slurry.

[0057] Step S4, weigh 35°C tap water according to the weight ratio of the second part of water / the second dry material = 0.0325, add the water to the GLS-65 aqueous paste, use a high-speed homogenizer to homogenize for 5 seconds to obtain an aluminum powder suspension, and pour the aluminum powder suspension into the first slurry, and at the same time weigh 35°C tap water according to the weight ratio of the third part of water / the second dry material = 0.0975, rinse with water in 3 times, stir at a rotation speed of 285rpm and a revolution speed of 125rpm for 8s, and then stir at a rotation speed of 140rpm and a revolution speed of 62rpm for 40s to obtain a second slurry.

[0058] Step S5, pouring and stopping the second slurry in sequence to obtain a wet billet, stopping it in an oven at 45°C for 150 minutes, using a steel wire to cut off the bread head and remove the mold.

[0059] Step S6, placing the wet blank into a steam curing box, first keeping it at a steam temperature of 60°C for 30 minutes, then keeping it at a steam temperature of 70°C for 6 days, and finally keeping it in an oven at 45°C for 5 days for steam curing to obtain aerated concrete blocks.

[0060] Examples 2 to 4

[0061] The only difference from Example 1 is that the ratios of the raw material components in step S1 are different, see Table 3 for details.

[0062] Example 5

[0063] The only difference from Example 1 is that the specific surface area of ​​the fly ash aluminum extraction residue is 60m 2 / g, particle size D90 is 75μm; the average true density is 1.3g / cm3 , bulk density is 0.3g / cm 3 .

[0064] Example 6

[0065] The only difference from Example 1 is that the specific surface area of ​​the fly ash aluminum extraction residue is 100m 2 / g, particle size D90 is 70μm; the average true density is 2.35g / cm 3 , bulk density is 0.6g / cm 3 .

[0066] Example 7

[0067] The only difference from Example 1 is that, by weight percentage, the moisture content of the gypsum is 16%, and the content of CaSO4·2H2O is 85%.

[0068] Example 8

[0069] The only difference from Example 1 is that the cement content is different, and the grade is: 525 cement.

[0070] Example 9

[0071] The only difference from Example 1 is that the effective CaO content in the quicklime is 85%, the MgCO3 content is 12%, and the particle size is about 75 μm.

[0072] Example 10

[0073] The only difference from Example 1 is that, calculated by weight percentage, the effective Al in the aluminum powder paste is 90% and the particle size is about 75 μm.

[0074] Embodiment 11

[0075] The only difference from Example 1 is that

[0076] Step S1, drying the fly ash aluminum extraction residue at 130° C. for 40 hours, crushing it with a micro-crusher and setting it aside.

[0077] Step S2, first mix the fly ash acid method aluminum extraction residue with the power plant desulfurization gypsum to obtain the first dry material, and stir it at a rotation speed of 275rpm and a revolution speed of 135rpm for 50s; then add cement and quicklime powder, mix to obtain the second dry material, and stir it at a rotation speed of 135rpm and a revolution speed of 67rpm for 270s.

[0078] Step S3, weigh 32° C. tap water according to the weight ratio of the first part of water / the second dry material = 0.73, add the water to the second dry material, first stir at a rotation speed of 275 rpm and a revolution speed of 135 rpm for 25 s, and then stir at a rotation speed of 135 rpm and a revolution speed of 67 rpm for 200 s to obtain a first slurry.

[0079] Step S4, weigh 32°C tap water according to the weight ratio of the second part of water / the second dry material = 0.03, add the water to the GLS-65 aqueous paste, use a high-speed homogenizer to homogenize for 5 seconds to obtain an aluminum powder suspension, and pour the aluminum powder suspension into the first slurry, and at the same time weigh 32°C tap water according to the weight ratio of the third part of water / the second dry material = 0.09, rinse the water three times in sequence, stir at a rotation speed of 275rpm and a revolution speed of 135rpm for 10s, and then stir at a rotation speed of 135rpm and a revolution speed of 67rpm for 35s to obtain a second slurry.

[0080] Step S5, pouring and stopping the second slurry in sequence to obtain a wet billet, stopping it in an oven at 40°C for 170 minutes, using a steel wire to cut off the bread head and remove the mold.

[0081] Step S6, putting the wet blank obtained in step S5 into a steam curing kettle box, first keeping it at a steam temperature of 55°C for 35 minutes, then keeping it at a temperature of 60°C for 7 days; finally, keeping it in an oven at 40°C for 6 days for steam curing to obtain aerated concrete blocks.

[0082] Example 12

[0083] The only difference from Example 1 is that

[0084] Step S1, drying the fly ash aluminum extraction residue at 90° C. for 60 hours, crushing it with a micro-crusher, and setting it aside.

[0085] Step S2, first mix the fly ash acid method aluminum extraction residue with the power plant desulfurization gypsum to obtain the first dry material, and stir it at a rotation speed of 295rpm and a revolution speed of 115rpm for 70s; then add cement and quicklime powder, mix to obtain the second dry material, and stir it at a rotation speed of 145rpm and a revolution speed of 57rpm for 210s.

[0086] Step S3, weigh 38°C tap water at a weight ratio of the first part of water / the second dry material = 0.70, add the water to the second dry material, first stir at a rotation speed of 295rpm and a revolution speed of 115rpm for 15s, and then stir at a rotation speed of 145rpm and a revolution speed of 57rpm for 240s to obtain a first slurry.

[0087] Step S4, weigh 38°C tap water according to the weight ratio of the second part of water / the second dry material = 0.0375, add the water to the GLS-65 aqueous paste, use a high-speed homogenizer to homogenize for 5 seconds to obtain an aluminum powder suspension, and pour the aluminum powder suspension into the first slurry, and at the same time weigh 38°C tap water according to the weight ratio of the third part of water / the second dry material = 0.1125, rinse with water three times in sequence, stir at a rotation speed of 295rpm and a revolution speed of 115rpm for 6s, and then stir at a rotation speed of 145rpm and a revolution speed of 57rpm for 45s to obtain a second slurry.

[0088] Step S5, pouring and stopping the second slurry in sequence to obtain a wet billet, stopping it in an oven at 50°C for 130 minutes, using a steel wire to cut off the bread head and remove the mold.

[0089] Step S6, putting the wet blank obtained in step S5 into a steam curing kettle box, first keeping it at a steam temperature of 65°C for 25 minutes, then keeping it at a temperature of 80°C for 5 days; finally, keeping it in an oven at 50°C for 4 days for steam curing to obtain aerated concrete blocks.

[0090] Comparative Example 1

[0091] The specific composition of aerated concrete blocks is shown in Table 3.

[0092] The only difference from Example 1 is that fly ash is used as the raw material component to replace the fly ash aluminum extraction residue. The chemical composition of the fly ash is shown in Table 4 below:

[0093] Table 4

[0094] Element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO CaO <![CDATA[K2O]]> <![CDATA[Na2O]]> <![CDATA[TiO2]]> <![CDATA[P2O5]]> <![CDATA[Fe2O3]]> wt% 45.36 38.49 0.11 0.16 0.40 0.08 0.44 0.04 0.32

[0095] Comparative Example 2

[0096] The only difference from Example 2 is that the fly ash shown in Table 4 is used as the raw material component to replace the fly ash aluminum extraction residue.

[0097] The above embodiments and comparative examples were each molded into three 100 mm×100 mm×100 mm cubic specimens, and the compressive strength and dry density were tested. The average values ​​of the test results are shown in Table 5.

[0098] Test Method

[0099] Compressive strength and dry density: tested according to "Autoclaved Aerated Concrete Block" (GB / T 11968-2020).

[0100] Table 3

[0101]

[0102]

[0103] Table 5

[0104] project Compressive strength(MPa) <![CDATA[Dry density (Kg / m 3 )]]> Example 1 4.2 540 Example 2 4.6 550 Example 3 5.5 590 Example 4 4.1 520 Example 5 3.9 510 Example 6 4.1 530 Example 7 4.2 530 Example 8 4.1 535 Example 9 4.0 530 Example 10 3.9 520 Embodiment 11 4.1 542 Example 12 4.2 535 Comparative Example 1 2.6 710 Comparative Example 2 3.2 715

[0105] From the data in the compressive strength and dry density test result table, it can be seen that compared with the aerated concrete blocks obtained in other embodiments, the comparative example 1 uses fly ash as the main component, and the compressive strength of the aerated concrete blocks obtained is reduced by about 25% compared with that in embodiment 1, and the dry density is significantly increased; the comparative example 2 uses fly ash as the main component, and the compressive strength of the aerated concrete blocks obtained is also reduced by about 15% compared with that in embodiment 2, and the dry density is significantly increased.

[0106] It can be seen from the above that, compared with the comparative example, the embodiments of the present invention use fly ash aluminum extraction residue, gypsum, quicklime, cement, and aluminum powder paste as raw materials to prepare aerated concrete blocks. On the one hand, a large amount of industrial solid waste such as fly ash aluminum extraction residue and power plant desulfurization gypsum can be consumed. On the other hand, waste can be turned into treasure to obtain aerated concrete blocks required in the construction field, thereby reducing environmental pollution while increasing economic and social benefits.

[0107] In addition, in the preparation methods of the embodiments of the present invention, fly ash aluminum extraction residue, gypsum, quicklime, and cement are uniformly mixed, aluminum powder paste and water are added to expand and then steam cured to form, effective calcium reacts with silicon dioxide under steam to form calcium silicate gel material, aluminum powder paste undergoes chemical reaction to generate hydrogen, and further generates a porous structure in the block, and finally obtains aerated concrete blocks with high strength and low dry density. That is, the preparation method of the present invention has simple process conditions, is easy to operate, has high feasibility, is more suitable for the preparation of the above-mentioned aerated concrete blocks of the present invention, has strong practicality, and can be widely promoted and utilized.

[0108] Moreover, it can be seen that when the process parameters are within the preferred range of the present invention, the aerated concrete block has a higher compressive strength and a lower dry density.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An aerated concrete block, characterized in that: Calculated by weight percentage, the raw materials of the aerated concrete building block include 58-74% of fly ash aluminum extraction residue, 2-3% of gypsum, 7-14% of cement, 16-29% of quicklime and 0.05-0.08% of aluminum powder paste.

2. The aerated concrete block according to claim 1, characterized in that: The fly ash aluminum extraction residue includes a fluidized bed fly ash acid method aluminum extraction residue; Preferably, the specific surface area of ​​the fly ash aluminum extraction residue is 60 to 100 m 2 / g, particle size D90≤75μm; and / or, The true density of the fly ash aluminum extraction residue is 1.3-2.35 g / cm 3 , bulk density is 0.3~0.6g / cm 3 .

3. The aerated concrete block according to claim 1 or 2, characterized in that: The gypsum includes desulfurization gypsum from a power plant; preferably, the moisture content of the gypsum is ≤16% by weight, and the content of CaSO4·2H2O in the gypsum is ≥85%; and / or, The cement includes one or more of 425 cement, 325 cement and 525 cement; and / or, The quicklime comprises 90% quicklime; preferably, by weight percentage, the effective CaO content in the quicklime is ≥85%, the MgCO3 content is ≤12%, and the particle size is 40-75 μm; and / or, The aluminum powder paste comprises GLS-65 water-based paste; preferably, in terms of weight percentage, the effective Al in the aluminum powder paste is ≥ 90%, and the particle size is ≤ 75 μm.

4. The method for preparing an aerated concrete block according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1, drying and crushing the fly ash aluminum extraction residue in sequence to obtain a first dry material; Step S2, adding gypsum to the first dry material and performing a first stirring; then adding cement and quicklime and performing a second stirring to obtain a second dry material; Step S3, adding the first portion of water to the second dry material, performing a third stirring to obtain a first slurry; Step S4, mixing the aluminum powder paste with the second portion of water, and then adding the mixture to the first slurry, and adding the third portion of water, and sequentially washing and stirring the mixture for the fourth time to obtain a second slurry; Step S5, pouring and stopping the second slurry in sequence to obtain a wet blank; Step S6, steam curing the wet blank to obtain the aerated concrete block.

5. The method for preparing an aerated concrete block according to claim 4, characterized in that: In the step S1, the drying temperature is 90-130° C. and the drying time is 40-60 hours.

6. The method for preparing an aerated concrete block according to claim 4 or 5, characterized in that: In the step S2, The first stirring is performed at a rotation speed of 285±10 r / min, a revolution speed of 125±10 r / min, and a time of 50 to 70 s; and / or, The second stirring process has a rotation speed of 140±5 r / min, a revolution speed of 62±5 r / min, and a time of 210 to 270 s.

7. The method for preparing an aerated concrete block according to any one of claims 4 to 6, characterized in that: In the step S3, The weight ratio of the first part of water to the second dry material is (70-73):100; and / or, The first portion of water is added at a temperature of 32-38° C.; and / or, The third stirring includes a third front stirring and a third rear stirring performed sequentially, wherein the third front stirring is stirred for 15 to 25 seconds at a rotation speed of 285±10r / min and a revolution speed of 125±10r / min, and the third rear stirring is stirred for 200 to 240 seconds at a rotation speed of 140±5r / min and a revolution speed of 62±5r / min.

8. The method for preparing an aerated concrete block according to any one of claims 4 to 7, characterized in that: In the step S4, The weight ratio of the second part of water to the second dry material is (3-3.75):100, and the weight ratio of the third part of water to the second dry material is (9-11.25):100; and / or, The fourth stirring includes a fourth front stirring and a fourth rear stirring performed sequentially, the fourth front stirring is stirred for 6 to 10 seconds at a rotation speed of 285±10r / min and a revolution speed of 125±10r / min, and the fourth rear stirring is stirred for 35 to 45 seconds at a rotation speed of 140±5r / min and a revolution speed of 62±5r / min.

9. The method for preparing an aerated concrete block according to any one of claims 4 to 8, characterized in that: In the step S5, the temperature of the static state is 40-50° C., and the time is 130-170 minutes.

10. The method for preparing an aerated concrete block according to any one of claims 4 to 9, characterized in that: In step S6, the steam curing includes: keeping the wet blank in a steam environment at 55-65° C. for 25-35 minutes, then keeping it in a steam environment at 60-80° C. for 5-7 days, and finally keeping it in a drying condition at 40-50° C. for 4-6 days.

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