High-toughness aac plate with heavy metal solidification function and preparation method thereof

Abstract

The present application relates to autoclaved aerated concrete plate technical field, specifically to high toughness AAC plate with heavy metal solidification function and a preparation method thereof. The present application makes full use of the silicon dioxide in fluorite tailings, copper tailings and spodumene tailings as siliceous material, uses cement, quicklime and other alkaline materials as calcareous material, adds appropriate amount of aluminum powder paste and other gas forming agents as pore forming agent, appropriate amount of coagulation regulator, appropriate amount of nano Y type molecular sieve and high efficiency toughening agent, and through steam curing (temperature < 200 DEG C), the autoclave is discharged, and a kind of high toughness AAC plate with heavy metal solidification function is prepared.

Description

Technical Field

[0001] This invention relates to the field of autoclaved aerated concrete (AAC) panels, specifically to high-toughness AAC panels with heavy metal curing function and their preparation method. Background Technology

[0002] In the preparation of autoclaved aerated concrete (AAC) panels, industrial or mining tailings are often used as raw materials to improve resource utilization. However, most industrial and mining tailings have high heavy metal content, posing a safety risk of heavy metal leaching when used as wall materials, potentially harming the environment and human health. Therefore, existing technologies typically involve adding heavy metal curing agents during the preparation process, combined with a high-temperature, high-pressure autoclaving process, to solidify and stabilize the heavy metals, thereby reducing the environmental risks during tailings utilization and achieving certain environmental benefits.

[0003] In addition, AAC panels, as an inorganic silicate wall material formed through high-temperature and high-pressure steam curing, inherently possess natural defects such as susceptibility to cracking and brittleness. During autoclaving, subsequent transportation, and construction and installation, the panels are prone to appearance quality problems such as cracking and chipping, directly affecting their functionality and engineering application results. Summary of the Invention

[0004] Based on this, the present invention provides a high-toughness AAC sheet with heavy metal curing function and its preparation method, which solves at least one problem in the prior art.

[0005] In a first aspect, the present invention provides a high-toughness AAC board with heavy metal curing function, comprising the following raw materials in parts by weight: 40-60 parts of fluorite tailings, 5-20 parts of copper tailings, 5-10 parts of spodumene tailings, 6-15 parts of cement, 10-20 parts of quicklime, 3-5 parts of setting regulator, 0.5-1.8 parts of nano Y-type molecular sieve, 0.5-1.8 parts of high-efficiency toughening agent, 0.02-0.04 parts of gas generating agent, and 90-150 parts of water.

[0006] Secondly, the present invention provides a method for preparing the high-toughness AAC board with heavy metal curing function, which includes the following steps: Grind fluorite tailings, copper tailings and spodumene tailings separately; The ground fluorite tailings, copper tailings, and spodumene tailings are mixed with water to make a slurry. The slurry is mixed with cement, quicklime, setting regulator, nano Y-type molecular sieve, high-efficiency toughening agent and water to prepare a mixed slurry; The gas-generating agent is mixed with water and then added to the slurry. The mixture is stirred evenly and cured at 50~60℃. The mixture is then cut into boards and steam-cured at a steam pressure of 1.2~1.5MPa and a temperature of 185~200℃ to obtain high-toughness AAC boards with heavy metal curing function.

[0007] Due to the adoption of the above technical solutions, the embodiments of the present invention have at least the following beneficial effects: by using mineral processing tailings to replace natural river sand resources, and by adding nano Y-type molecular sieves and high-efficiency toughening agents, a high-toughness AAC board with heavy metal curing function is prepared by a simple method, realizing waste utilization and improving the performance of AAC board. Attached Figure Description

[0008] Figure 1 This is a SEM image of the AAC board material in Embodiment 1 of the present invention.

[0009] Figure 2 This is a SEM image of the AAC board material in Comparative Example 1 of this invention.

[0010] Figure 3 This is a photograph of the AAC board material in Embodiment 1 of the present invention.

[0011] Figure 4 This is a photograph of the AAC sheet material in Comparative Example 1 of this invention. Detailed Implementation

[0012] The following will provide a clear and complete description of the concept and technical effects of the present invention, so as to fully explain the purpose, solution and effects of the present invention.

[0013] In order to effectively utilize mineral processing tailings and improve the performance of AAC plates, this invention provides a high-toughness AAC plate with heavy metal curing function and its preparation method.

[0014] In a first aspect, the present invention provides a high-toughness AAC board with heavy metal curing function, comprising the following raw materials in parts by weight: 40-60 parts of fluorite tailings, 5-20 parts of copper tailings, 5-10 parts of spodumene tailings, 6-15 parts of cement, 10-20 parts of quicklime, 3-5 parts of setting regulator, 0.5-1.8 parts of nano Y-type molecular sieve, 0.5-1.8 parts of high-efficiency toughening agent, 0.02-0.04 parts of gas generating agent, and 90-150 parts of water.

[0015] In this invention, silica in fluorite tailings, copper tailings, and spodumene tailings is fully utilized as a siliceous material. The utilization rate of mineral processing tailings accounts for more than 75% of the total raw materials (excluding water), resulting in high waste utilization rate and the advantages of being green and low-carbon.

[0016] By adding an appropriate amount of nano-Y-type molecular sieves, the silica-alumina ratio (5.0~6.5), pore size (approximately 0.74 nm), and pore volume (0.3~0.4 cm³) can be utilized. 3 Structural characteristics such as / g) enable it to accommodate heavy metal ions with large hydration radii (such as Pb). 2+ Hydration radius approximately 0.8 nm, Cu 2+ Approximately 0.73 nm, Zn 2+ Approximately 0.74 nm), physical retention is achieved through a "pore encapsulation" effect. The numerous silicon-aluminum bridged oxygen bonds (Si-O-Al) in the nano-Y-type molecular sieve framework give it a negative surface charge, requiring the adsorption of Na to balance the charge. + Ca 2 + K + These cations are cations that can react with heavy metal ions (such as Cd). 2+ Cu 2+ This process involves highly efficient ion exchange, thereby achieving the solidification of heavy metals. The specific surface area of ​​nano-Y-type molecular sieves can reach 600~900 m². 2 / g, with a large number of hydroxyl (-OH) and silicon-oxygen free radicals (Si-O) exposed on the surface. Active groups such as ) provide chemical coordination sites for heavy metal ions.

[0017] Utilizing the unique pore structure, high specific surface area, and chemical activity of nano-Y-type molecular sieves, they can fill the capillary and pore gaps inside autoclaved aerated concrete (AAC), reducing the formation of large-pore defects. Simultaneously, nano-Y-type molecular sieves can guide the directional growth of hydration products such as tobermorite on the pore surface, resulting in a denser and more uniform crystal arrangement and reducing the porosity of the product. Furthermore, nano-Y-type molecular sieves possess excellent adsorption and ion exchange capabilities, enabling them to adsorb moisture and reactive ions (such as Ca2+) generated during the autoclaving process. 2+ Si 4+ This increases the local ion concentration, thereby accelerating the hydration reaction between cement, siliceous materials and lime, promoting the formation of products such as tobermorite and hydrated calcium silicate gel, increasing the system density, reducing the drying shrinkage value (<0.40mm / m), and reducing the risk of cracking.

[0018] In some optional embodiments, the high-toughness AAC board with heavy metal curing function comprises the following raw materials in parts by weight: 55 parts fluorite tailings, 8 parts copper tailings, 5 parts spodumene tailings, 10 parts cement, 18 parts quicklime, 4 parts setting regulator, 1.0 part nano Y-type molecular sieve, 1.5 parts high-efficiency toughening agent, 0.03 parts gas generating agent, and 100 parts water.

[0019] In some optional embodiments, the nano-Y-type molecular sieve is primarily composed of nanoscale materials made of silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra, with a particle size ranging from 1 to 100 nm. It possesses a regular microporous structure (pore size generally less than 2 nm) and exhibits functions such as tight packing, induced crystallization, and chemical activity. The silicon-to-aluminum ratio of the Y-type molecular sieve is 3.0 to 6.5, preferably 5.0 to 6.5. More preferably, the nano-Y-type molecular sieve is a NaY-type molecular sieve.

[0020] In some optional embodiments, the fluorite tailings contain ≥81% silica by mass and ≤5% mud content.

[0021] In some optional embodiments, the copper tailings are tailings generated after copper concentrate beneficiation, with a silica mass fraction ≥70% and a mud content ≤10%.

[0022] In some optional embodiments, the spodumene tailings are tailings generated after the beneficiation of lithium carbonate (Li2CO3) concentrate from spodumene ore, with a silica mass fraction ≥75% and a mud content ≤10%.

[0023] In some optional embodiments, the cement is ordinary Portland cement or R-type general-purpose Portland cement with a strength grade of not less than 42.5.

[0024] In some optional embodiments, the total mass fraction of calcium oxide and magnesium oxide in the quicklime is ≥65%, the digestion rate is ≤15min, and the digestion temperature is ≥60℃.

[0025] In some optional embodiments, the setting regulator is one or a mixture of several of natural dihydrate gypsum, desulfurized gypsum, and phosphogypsum.

[0026] In some alternative embodiments, the gas-generating agent is one or a mixture of aluminum powder paste, sodium bicarbonate, or aluminum powder paste.

[0027] In some optional embodiments, the high-efficiency toughening agent is one or a mixture of several of zirconium oxide (ZrO2), yttrium oxide (Y2O3), and cerium oxide (CeO3). Preferably, the high-efficiency toughening agent is zirconium oxide (ZrO2). Since tetragonal zirconium oxide (ZrO2) exists in a metastable state at room temperature, it undergoes a t→m phase transformation under the stress at the crack tip, causing a volume expansion rate of 3% to 5%, thereby forming a compressive stress field that hinders crack propagation in AAC plates and reduces the risk of cracking in AAC plates.

[0028] Secondly, the present invention provides a method for preparing the high-toughness AAC board with heavy metal curing function, which includes the following steps: S100, grind fluorite tailings, copper tailings and spodumene tailings respectively; S200: Mix the ground fluorite tailings, copper tailings, and spodumene tailings with water to make a slurry; S300: Mix the slurry with cement, quicklime, setting regulator, nano Y-type molecular sieve, high-efficiency toughening agent and water to prepare a mixed slurry; S400. After mixing the gas-generating agent with water, add it to the slurry mixture, stir evenly, cure at 50~60℃, then cut into boards, and autoclave at a steam pressure of 1.2~1.5MPa and a temperature of 185~200℃ to obtain a high-toughness AAC board with heavy metal curing function.

[0029] In some optional embodiments, in step S100, the fluorite tailings, copper tailings, and spodumene tailings can be ground to a specific surface area ≥350 m². 2 / g.

[0030] In some optional embodiments, in step S200, water can be added to the ground fluorite tailings, copper tailings, and spodumene tailings, and stirred evenly to form a slurry.

[0031] In some optional embodiments, in step S300, cement, quicklime, setting regulator, nano Y-type molecular sieve, and high-efficiency toughening agent can be added to the slurry and stirred for 65 seconds to prepare a mixed slurry.

[0032] In some optional embodiments, in step S400, the gas-generating agent can be first dispersed in water and then added to the mixed slurry, stirred evenly, poured into a mold frame, and cured at 55°C to achieve cutting strength for cutting; and then steam-cured at a steam pressure of 1.3MPa and a temperature of 195°C for 10 hours to obtain AAC board.

[0033] The following are some typical implementation examples.

[0034] Example 1 Prepare the AAC board according to the following steps: (1) After drying, fluorite tailings, copper tailings, and spodumene tailings are ground to a specific surface area greater than 370 m². 2 / g; (2) Take 55 parts of fluorite tailings, 8 parts of copper tailings, and 5 parts of spodumene tailings, add 40 parts of water, and make a slurry; (3) Add 10 parts cement, 18 parts quicklime, 4 parts natural gypsum, 1.0 part nano Y-type molecular sieve, 1.5 parts zirconium oxide, and 60 parts water, stir for 65 s to make a mixed slurry; (4) Disperse 0.03 parts of aluminum powder paste in 2 parts of water, add it to the mixed slurry, and stir for 15 seconds; pour it into the mold frame and cure (temperature is 55℃) for 1.5 h to make it reach the cutting strength; cut it into 6000mm×600mm×200mm plates, and then steam cure (pressure 1.3MPa, temperature is 195℃) for 10 h, and get AAC plates out of the autoclave.

[0035] Example 2 Prepare the AAC board according to the following steps: (1) After drying, fluorite tailings, copper tailings, and spodumene tailings are ground to a specific surface area of ​​360 m². 2 / g; (2) Take 55 parts of fluorite tailings, 8 parts of copper tailings, and 5 parts of spodumene tailings, add 40 parts of water, and make a slurry; (3) Add 10 parts cement, 18 parts quicklime, 4 parts natural gypsum, 1.0 part nano Y-type molecular sieve, 1.5 parts zirconium oxide, and 60 parts water, stir for 65 s to make a mixed slurry; (4) Disperse 0.03 parts of aluminum powder paste in 2 parts of water, add it to the mixed slurry, and stir for 15 seconds; pour it into the mold frame and cure (temperature is 55℃) for 1.5 h to make it reach the cutting strength; cut it into 6000mm×600mm×200mm plates, and then steam cure (pressure 1.3MPa, temperature is 195℃) for 10 h, and get AAC plates out of the autoclave.

[0036] Comparative Example 1 The difference between this comparative example and Example 1 is that nano-Y-type molecular sieves and high-efficiency toughening agent (zirconia) were not used in the ingredients.

[0037] Comparative Example 2 The difference between this comparative example and Example 1 is that nano-X-type molecular sieves (10X-type molecular sieves) are used instead of nano-Y-type molecular sieves in the formulation. The nano-X-type molecular sieves have a silica-to-alumina ratio of 2.0 to 3.0 and a pore size of approximately 0.7 nm.

[0038] The AAC products obtained in Examples 1-2 and Comparative Examples 1-2 were tested, and Pb was measured. 2+ Leaching value, Cu 2+ The leaching value test method was performed according to Appendix B of GB5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification"; the drying shrinkage rate test method was performed according to GB / T11969-2020; and the transverse and longitudinal crack and chipped corner test methods were performed according to GB / T15762-2020. The test results are shown in Table 1.

[0039] Table 1. Performance test results of products obtained in Examples 1-2 and Comparative Examples 1-2 As shown in Table 1, the AAC plate prepared by this invention has the advantages of low shrinkage and high toughness, with a drying shrinkage value of 0.37~0.40 mm / m, exhibiting excellent volume stability; no longitudinal cracks or chipped edges or corners were observed, overcoming the brittleness of silicate inorganic materials, and possessing high toughness and high crack resistance; heavy metal Pb... 2+ Cu 2+ The leaching values ​​were 3.6 μg / L and 29.8 μg / L, respectively, both lower than the leaching toxicity standard limit.

[0040] Compared with Comparative Example 1, the drying shrinkage value of the AAC board in Example 1 decreased from 0.49 mm / m to 0.40 mm / m, a reduction of 18.4%, indicating that adding an appropriate amount of high-efficiency toughening agent and nano-Y-type molecular sieve is beneficial to reducing the volume shrinkage rate of the AAC board. In terms of appearance quality, the number of longitudinal cracks decreased from 1 to 0, and the number of chipped edges and corners decreased from 1 to 0, indicating that adding an appropriate amount of nano-Y-type molecular sieve and high-efficiency toughening agent is beneficial to improving the toughness and crack resistance of the AAC board, and more effectively ensuring the safety of the AAC board in construction projects.

[0041] Figure 1 and Figure 2 The images show SEM images of the AAC plates prepared in Example 1 and Comparative Example 1, respectively. As can be seen from the SEM images, the addition of an appropriate amount of nano-Y-type molecular sieve and a high-efficiency toughening agent in Example 1 resulted in a large number of needle-like tobermorite particles being evenly distributed in the internal bubble walls of the plate, reducing internal structural defects and forming a uniform and dense porous structure.

[0042] Comparative Example 1: No nano-Y-type molecular sieve was incorporated into the preparation of the AAC plate. The prepared AAC plate contained the heavy metal Pb. 2+ Cu 2+ The leaching values ​​were 9.3 μg / L and 68.0 μg / L, respectively, representing increases of 158.3% and 128.1%. This indicates that the incorporation of nano-Y-type molecular sieves reduced the amount of heavy metal Pb introduced into the raw materials for AAC plate preparation. 2+ Cu 2+ It has a significant curing effect.

[0043] In Comparative Example 2, nano-X-type molecular sieves were incorporated into the preparation of AAC plates instead of nano-Y-type molecular sieves. The resulting AAC plates contained the heavy metal Pb. 2+ Cu 2+ The leaching values ​​were 7.2 μg / L and 47.1 μg / L, respectively, representing increases of 100.0% and 58.2%, indicating that the nano-X-type molecular sieve effectively leached the heavy metal Pb. 2+ Cu 2+While it also exhibits some curing effect, it is not as effective as nano-Y-type molecular sieves. The reason lies in the relatively low silica-to-alumina ratio of nano-X-type molecular sieves, ranging from 2.0 to 3.0. During high-temperature and high-pressure autoclaving of AAC boards, the combined effects of high temperature, moisture, and pressure can damage the structure of the X-type molecular sieve, thus affecting its curing effect. In contrast, Y-type molecular sieves have a silica-to-alumina ratio ranging from 3.0 to 6.0. This higher ratio results in a more stable framework and better hydrothermal stability, preventing molecular structure damage during autoclaving and thus achieving the effects of heavy metal curing and reduced shrinkage.

[0044] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any embodiment that achieves the technical effects of the present invention by the same or equivalent means should fall within the protection scope of the present invention. Within the protection scope of the present invention, various modifications and variations can be made to the technical solutions and / or implementation methods.

Claims

1. A high-toughness AAC board with heavy metal curing function, characterized in that, The raw materials include the following parts by weight: 40-60 parts fluorite tailings, 5-20 parts copper tailings, 5-10 parts spodumene tailings, 6-15 parts cement, 10-20 parts quicklime, 3-5 parts setting regulator, 0.5-1.8 parts nano Y-type molecular sieve, 0.5-1.8 parts high-efficiency toughening agent, 0.02-0.04 parts gas generating agent, and 90-150 parts water.

2. The high-toughness AAC board with heavy metal curing function according to claim 1, characterized in that, The high-toughness AAC board with heavy metal curing function comprises the following raw materials in parts by weight: 55 parts fluorite tailings, 8 parts copper tailings, 5 parts spodumene tailings, 10 parts cement, 18 parts quicklime, 4 parts setting regulator, 1.0 part nano Y-type molecular sieve, 1.5 parts high-efficiency toughening agent, 0.03 parts gas generating agent, and 100 parts water.

3. The high-toughness AAC board with heavy metal curing function according to claim 1, characterized in that, The silicon-to-aluminum ratio of the Y-type molecular sieve is 3.0 to 6.

5.

4. The high-toughness AAC board with heavy metal curing function according to claim 1, characterized in that, The nano-Y-type molecular sieve is a NaY-type molecular sieve.

5. The high-toughness AAC board with heavy metal curing function according to claim 1, characterized in that, The fluorite tailings have a silica mass fraction of ≥81% and a mud content of ≤5%; the copper tailings are tailings generated after copper concentrate beneficiation, with a silica mass fraction of ≥70% and a mud content of ≤10%; the spodumene tailings are tailings generated after lithium carbonate concentrate beneficiation from spodumene ore, with a silica mass fraction of ≥75% and a mud content of ≤10%.

6. The high-toughness AAC board with heavy metal curing function according to claim 1, characterized in that, The setting regulator is one or a mixture of several of the following: natural dihydrate gypsum, desulfurized gypsum, and phosphogypsum.

7. The high-toughness AAC board with heavy metal curing function according to claim 1, characterized in that, The gas-generating agent is one of aluminum powder paste, sodium bicarbonate, or a mixture thereof.

8. The high-toughness AAC board with heavy metal curing function according to claim 1, characterized in that, The high-efficiency toughening agent is one or a mixture of several of zirconium oxide, yttrium oxide, and cerium oxide.

9. The method for preparing high-toughness AAC sheet with heavy metal curing function according to any one of claims 1-8, characterized in that, Includes the following steps: Grind fluorite tailings, copper tailings and spodumene tailings separately; The ground fluorite tailings, copper tailings, and spodumene tailings are mixed with water to make a slurry. The slurry is mixed with cement, quicklime, setting regulator, nano Y-type molecular sieve, high-efficiency toughening agent and water to prepare a mixed slurry; The gas-generating agent is mixed with water and then added to the slurry. The mixture is stirred evenly and cured at 50~60℃. The mixture is then cut into boards and steam-cured at a steam pressure of 1.2~1.5MPa and a temperature of 185~200℃ to obtain high-toughness AAC boards with heavy metal curing function.

10. The method according to claim 9, characterized in that, Fluorite tailings, copper tailings, and spodumene tailings are ground to a specific surface area ≥350 m². 2 / g.

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