A high-strength ceramic using aluminum tailings as raw material and preparation method thereof

Abstract

The present invention discloses a high-strength ceramic using aluminum tailings as raw materials and a preparation method thereof. The ceramic is made of the following components, measured by weight: 30-60 parts of modified aluminum tailings, 15-30 parts of diopside, 10-25 parts of kaolin, 5-20 parts of silicon nitride whiskers, 2-5 parts of carboxymethyl cellulose, 0.2-1 part of soybean oil, 1-3 parts of glycerol, and 20-35 parts of water. The present invention can convert a large amount of stockpiled aluminum tailings into a high-value-added ceramic product. The ceramic has a lightweight feature while ensuring high mechanical strength, and both flexural strength and fracture toughness reach advanced levels, and has excellent thermal stability and thermal shock resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramics, and in particular to a high-strength ceramic using aluminum tailings as a raw material and a preparation method thereof. Background Art

[0002] With the rapid development of my country's aluminum industry, the amount of aluminum tailings generated during bauxite mining and alumina production has increased dramatically. Statistics show that every ton of alumina produced generates approximately 1.5 to 2 tons of aluminum tailings. my country's annual aluminum tailings production exceeds 60 million tons, with accumulated stockpiles reaching billions of tons.

[0003] As important structural and functional materials, ceramics are in huge demand in fields such as construction, machinery, electronics, and aerospace. Traditional ceramics are primarily based on natural mineral raw materials, such as kaolin, feldspar, and quartz. However, with the increasing shortage of high-quality natural raw materials and the rising cost of mining, the ceramic industry urgently needs to find alternative raw materials. At the same time, modern industry is placing increasingly stringent demands on the performance of ceramic materials, particularly in terms of high strength, high toughness, and lightweight properties. Traditional ceramic materials are no longer able to meet these requirements.

[0004] CN112919893A discloses a method for preparing mullite-based composite ceramics using low-temperature sintering of bauxite tailings. The method uses bauxite tailings, bauxite clinker, and lithium porcelain stone as the main raw materials. The mullite-based composite ceramics are prepared through batching, ball milling, molding, and low-temperature sintering. The mullite-based composite ceramics prepared using low-temperature sintering of bauxite tailings exhibit high compressive strength, low linear shrinkage, high bulk density, and a simple preparation process. They are suitable for applications in industries such as high-value utilization of bauxite tailings and ceramics.

[0005] Existing technologies usually use aluminum tailings as ceramic raw materials by direct addition or simple pretreatment, but there are the following obvious shortcomings: first, aluminum tailings particles are easy to agglomerate and have poor dispersion, resulting in uneven ceramic green body, affecting the mechanical properties of the final product; second, the interface bonding between aluminum tailings and other raw materials is not strong, and defects are easily generated during the sintering process, limiting the improvement of ceramic strength; third, the strength of ceramic products prepared by existing processes is generally low, which is difficult to meet the requirements of high-performance applications; finally, there is a lack of effective surface modification technology, and the potential value of aluminum tailings has not been fully realized.

[0006] Therefore, there is an urgent need to develop a new technical solution to improve the dispersibility and interface bonding properties of aluminum tailings through effective surface modification of aluminum tailings, and to prepare high-strength and high-toughness ceramic materials through scientific formula design and process optimization, so as to solve the problem of comprehensive utilization of aluminum tailings and meet the market demand for high-performance ceramic materials. Summary of the Invention

[0007] In order to address the shortcomings of the existing technology, the purpose of the present invention is to provide a high-strength ceramic using aluminum tailings as raw materials and a preparation method thereof. The ceramic has the characteristics of lightweight while ensuring high mechanical strength, and its flexural strength and fracture toughness have reached advanced levels. It has excellent thermal stability and thermal shock resistance and can meet the use requirements under harsh working conditions; more importantly, this technology converts a large amount of stockpiled aluminum tailings into high-value-added ceramic products, which not only solves the problem of industrial solid waste disposal, but also reduces environmental pollution and land occupation.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A high-strength ceramic using aluminum tailings as raw materials is prepared from the following components, calculated by weight: 30-60 parts of modified aluminum tailings, 15-30 parts of diopside, 10-25 parts of kaolin, 5-20 parts of silicon nitride whiskers, 2-5 parts of carboxymethyl cellulose, 0.2-1 part of soybean oil, 1-3 parts of glycerin, and 20-35 parts of water.

[0010] Preferably, the modified aluminum tailings are prepared by the following method steps:

[0011] (1) Add polyethylene glycol to deionized water and fully dissolve it, then add vinyl sulfonic acid, stir until completely dissolved, introduce nitrogen to deoxygenate, slowly add potassium persulfate aqueous solution dropwise, stir to react, cool the product, freeze-dry to obtain the modifier, and seal and store;

[0012] Modifier prepared by free radical polymerization: Potassium persulfate undergoes thermal decomposition under heating conditions to produce sulfate radicals. The strong oxidizing property of the polymer can extract hydrogen atoms from vinyl sulfonic acid molecules or directly add to C=C double bonds to form monomer free radicals. These reactive monomer free radicals react with more vinyl sulfonic acid molecules, forming a growing polymer chain. The hydroxyl groups at the polyethylene glycol end react with the growing free radicals to form a graft copolymer structure, simultaneously controlling the polymer's molecular weight and improving its water solubility. The resulting product is a water-soluble polymer modifier containing sulfonic acid side chains and polyethylene glycol grafted segments. The freeze-drying process removes moisture through sublimation, yielding a stable solid product.

[0013] Preferably, in step (1), the molecular weight of polyethylene glycol is 800-2000; the concentration of the potassium persulfate aqueous solution is 1-3 wt %; and the dosage ratio of polyethylene glycol, deionized water, vinyl sulfonic acid, and potassium persulfate aqueous solution is 1-3 g:30-60 mL:2-8 g:5-10 mL.

[0014] Preferably, in step (1), the potassium persulfate aqueous solution is added dropwise within 60-90 min, and the stirring reaction conditions are 70-85° C. and 200-400 r / min for 5-8 h.

[0015] (2) Add the modifier to deionized water, adjust the pH of the system, add aluminum tailings powder and zirconium oxide powder in sequence at a constant temperature, stir and react, and after the reaction is completed, centrifuge while hot, wash, and dry to obtain the modified aluminum tailings.

[0016] Surface coordination modification: After the modifier is dissolved, the system is strongly acidic and is adjusted to pH 6-8 by alkalinity. At this time, the sulfonic acid group is partially ionized. ions, and suitable pH conditions make the metal ions on the surface of aluminum tailings and zirconium oxide ( 、 、 The polymer modifier is in an active state (hydrated but not fully oxidized). The polymer modifier is adsorbed onto the mineral surface through multiple interactions: the sulfonic acid groups form coordination bonds with surface metal ions, the ether oxygen atoms in the polyethylene glycol segments also weakly coordinate with the metal ions, and the long polymer chains are further stabilized on the surface through physical entanglement and hydrogen bonding. After washing and drying, a surface-functionalized modified aluminum tailings composite material is obtained.

[0017] Preferably, in step (2), the usage ratio of the modifier, deionized water, aluminum tailings powder, and zirconium oxide powder is 0.4-1.6 g: 150-200 mL: 10 g: 0.5-3.5 g.

[0018] Preferably, in step (2), the pH of the system is adjusted to 6-8 with a dilute sodium hydroxide solution; aluminum tailings powder and zirconium oxide powder are added in sequence at a constant temperature of 50°C, and the feeding process is controlled within 10-30 minutes; the stirring reaction conditions are 45-55°C and 400-600 r / min for 3-6 hours; and the product is washed 4-6 times with hot deionized water at 50-60°C.

[0019] Preferably, in step (2), the particle size of the aluminum tailings powder is 45-75 μm, and the particle size of the zirconium oxide powder is 1-2 μm.

[0020] Preferably, the silicon nitride whisker has a diameter of 0.5-1.0 μm and a length of 20-50 μm; the diopside particle size is 70-110 μm; and the kaolin particle size is 800-1250 mesh.

[0021] Preferably, the aluminum tailings are bauxite tailings, the main components of which are 30-50 wt% of aluminum oxide, 25-45% of silicon dioxide, 1-10 wt% of iron oxide, 0.3-10 wt% of titanium dioxide, and other impurities not exceeding 10 wt%.

[0022] The present invention also claims protection for a preparation method for the high-strength ceramic using aluminum tailings as raw materials, comprising the following steps: adding modified aluminum tailings, diopside, kaolin, silicon nitride whiskers, and carboxymethyl cellulose to a ball mill and mixing for 6 to 9 minutes, then adding water and mixing for 3 to 6 minutes, adding soybean oil and glycerin and mixing for 8 to 12 minutes, adding the mixture to a molding machine for molding to form a green body, and sintering to obtain the high-strength ceramic using aluminum tailings as raw materials.

[0023] Preferably, the ball mill speed is 200~300r / min; the pressure in the molding machine is 20~30MPa, and the molding time is 3~5min; sintering is carried out in an air atmosphere in a muffle furnace, with a heating rate of 2~3℃ / min, first heating to 350~400℃, keeping warm for 30~40min, then heating to 600~700℃, keeping warm for 40~60min, then heating to 900~1000℃, keeping warm for 60~90min, and finally heating to 1200~1250℃, keeping warm for 90~120min.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention provides a high-strength ceramic with aluminum tailings as raw materials, with modified aluminum tailings as the main base material, realizing the comprehensive utilization and high-value conversion of aluminum tailings. After surface functionalization treatment, it has excellent dispersibility and interface bonding ability, providing a solid structural foundation for ceramics; diopside has excellent high-temperature stability and low thermal expansion coefficient, which can improve the sintering densification process of ceramics and improve the thermal shock stability of materials; kaolin, as a classic ceramic raw material, forms mullite phase during the sintering process, which significantly improves the mechanical strength of the ceramic, and its good plasticity is conducive to the forming of the green body; silicon nitride whiskers serve as high-performance reinforcing phases, and their unique fibrous structure can effectively prevent crack propagation, and greatly improve the fracture toughness and bending strength of ceramics through toughening mechanisms such as pull-out and bridging; carboxymethyl cellulose serves as an environmentally friendly organic binder, which provides sufficient green body strength at low temperatures and completely decomposes without leaving residue at high temperatures; soybean oil and glycerol serve as natural lubricants and plasticizers, respectively, which significantly improve the rheological properties and forming properties of ceramic slurry. The iron and titanium elements in aluminum tailings promote the formation of high-temperature melts, lowering sintering temperatures and contributing to energy conservation, emission reduction, and production cost reduction. The overall formulation of the present invention achieves a perfect balance of strength, toughness, formability, and cost-effectiveness, while also achieving high-value utilization of aluminum tailings and reducing the problems of land occupation and environmental pollution caused by aluminum tailings.

[0026] 2. The present invention provides a modified aluminum tailings. The modifier interacts with the surfaces of the aluminum tailings powder and zirconium oxide powder through coordination and other interactions. The numerous sulfonic acid functional groups in the modifier molecules impart a negative charge to the powder surface. This enables uniform dispersion of the slurry through steric hindrance and electrostatic repulsion, significantly improving the dispersibility of the powder, reducing agglomeration, and improving the uniformity and density of the ceramic. The modifier also has dual functional properties: it acts as a dispersant to improve particle dispersibility and as a pore-forming agent. During high-temperature sintering, it pyrolyzes, leaving a rich and uniform pore structure in the ceramic. This allows the prepared ceramic to maintain high porosity while maintaining excellent flexural strength, achieving an organic combination of lightweight and high strength. The zirconium element introduced into the modified aluminum tailings combines with the aluminum oxide in the base material to form an alumina-zirconia composite system, which significantly enhances the mechanical strength of the ceramic, thereby producing a truly high-strength ceramic. The modifier creates a three-dimensional network between the ceramic particles, providing the necessary strength and toughness, ensuring the green body maintains shape stability during processing, and contributing to the production of ceramic products with enhanced mechanical properties. This modification method converts aluminum tailings, which were originally difficult to use directly, into high-value-added ceramic raw materials. It not only solves the environmental pollution problem of aluminum tailings, but also provides the ceramic industry with a new type of raw material with excellent performance. It has strong process adaptability and can achieve densification at a relatively low sintering temperature, reducing energy consumption. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0028] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0029] The polyethylene glycol is PEG-1000;

[0030] Zirconia, with a purity of 99.5% and an average particle size of 1.5 μm, was purchased from Hangzhou Zhitai Purification Technology Co., Ltd., model VK-R55;

[0031] Kaolin is a triclinic crystal with a specific surface area of ​​10m 2 / g, purchased from Shijiazhuang Tourmaline Mineral Products Co., Ltd.

[0032] A method for preparing high-strength ceramics using aluminum tailings as raw materials comprises the following steps:

[0033] (1) Add 1-3 g of polyethylene glycol to 30-60 mL of deionized water and dissolve it thoroughly. Then add 2-8 g of vinyl sulfonic acid and stir until it is completely dissolved. Then, introduce nitrogen to remove oxygen. Slowly add 5-10 mL of 1-3 wt% potassium persulfate aqueous solution dropwise within 60-90 min. Stir and react at 70-85 ° C and 200-400 r / min for 5-8 h. Cool the product, freeze-dry it to obtain the modifier, and seal it for storage.

[0034] (2) Add 0.4-1.6 g of the modifier to 150-200 mL of deionized water, adjust the pH of the system to 6-8 with a dilute sodium hydroxide solution, add 10 g of aluminum tailings powder and 0.5-3.5 g of zirconium oxide powder in sequence at a constant temperature of 50°C, control the feeding process within 10-30 min, stir and react at 45-55°C and 400-600 r / min for 3-6 h, centrifuge while hot after the reaction is completed, wash the product with 50-60°C hot deionized water 4-6 times, and dry it to obtain the modified aluminum tailings;

[0035] (3) Add 30-60 parts of modified aluminum tailings, 15-30 parts of diopside, 10-25 parts of kaolin, 5-20 parts of silicon nitride whiskers, and 2-5 parts of carboxymethyl cellulose into a ball mill and mix at 200-300 r / min for 6-9 minutes. Then add 20-35 parts of water and mix for 3-6 minutes. Then add 0.2-1 parts of soybean oil and 1-3 parts of glycerol and mix for 8-12 minutes. Then add the mixture into a molding machine and mold it at 20-30 MPa for 3-5 minutes. in, making a green body, and sintering in an air atmosphere in a muffle furnace, first heating to 350-400°C at a heating rate of 2-3°C / min, keeping warm for 30-40 minutes, then heating to 600-700°C, keeping warm for 40-60 minutes, then heating to 900-1000°C, keeping warm for 60-90 minutes, and finally heating to 1200-1250°C, keeping warm for 90-120 minutes, to obtain the high-strength ceramic using aluminum tailings as raw materials.

[0036] The present invention will be further described below with reference to specific examples. Example 1

[0037] A method for preparing high-strength ceramics using aluminum tailings as raw materials comprises the following steps:

[0038] (1) Add 3 g of polyethylene glycol to 50 mL of deionized water and dissolve thoroughly. Then add 8 g of vinyl sulfonic acid and stir until completely dissolved. Then, introduce nitrogen to remove oxygen. Slowly add 10 mL of 2 wt% potassium persulfate aqueous solution dropwise within 80 min. Stir and react at 85 °C and 300 r / min for 5 h. Cool the product, freeze-dry it to obtain the modifier, and seal it for storage.

[0039] (2) 1.6 g of the modifier was added to 180 mL of deionized water, and the pH of the system was adjusted to 7 with a dilute sodium hydroxide solution. 10 g of aluminum tailings powder and 3.5 g of zirconium oxide powder were added in sequence at a constant temperature of 50 ° C. The addition process was controlled within 20 min. The mixture was stirred at 55 ° C and 500 r / min for 3 h. After the reaction was completed, the mixture was centrifuged while hot. The product was washed 5 times with 55 ° C hot deionized water and dried to obtain the modified aluminum tailings.

[0040] (3) 6000 g of modified aluminum tailings, 3000 g of diopside, 2500 g of kaolin, 2000 g of silicon nitride whiskers, and 500 g of carboxymethyl cellulose were added to a ball mill and mixed at 250 r / min for 8 min, then 3500 g of water was added and mixed for 5 min, 100 g of soybean oil and 300 g of glycerol were added and mixed for 10 min, and then added to a molding machine and molded at 25 MPa for 4 min to form a green body, which was sintered in an air atmosphere in a muffle furnace at a heating rate of 3 ° C / min, first heated to 380 ° C, kept warm for 35 min, then heated to 650 ° C, kept warm for 50 min, then heated to 950 ° C, kept warm for 75 min, and finally heated to 1220 ° C, kept warm for 100 min, to obtain the high-strength ceramics using aluminum tailings as raw materials. Example 2

[0041] A method for preparing high-strength ceramics using aluminum tailings as raw materials comprises the following steps:

[0042] (1) Add 2 g of polyethylene glycol to 50 mL of deionized water and dissolve thoroughly. Then add 6 g of vinyl sulfonic acid and stir until completely dissolved. Then, introduce nitrogen to remove oxygen. Slowly add 8 mL of 2 wt% potassium persulfate aqueous solution dropwise within 80 min. Stir and react at 80 °C and 300 rpm for 6 h. Cool the product, freeze-dry it to obtain the modifier, and seal it for storage.

[0043] (2) 0.8 g of the modifier was added to 180 mL of deionized water, and the pH of the system was adjusted to 7 with a dilute sodium hydroxide solution. 10 g of aluminum tailings powder and 2.5 g of zirconium oxide powder were added in sequence at a constant temperature of 50 ° C. The addition process was controlled within 20 min. The mixture was stirred at 50 ° C and 500 r / min for 4 h. After the reaction was completed, the mixture was centrifuged while hot. The product was washed 5 times with 55 ° C hot deionized water and dried to obtain the modified aluminum tailings.

[0044] (3) 5000 g of modified aluminum tailings, 2500 g of diopside, 2000 g of kaolin, 1500 g of silicon nitride whiskers, and 400 g of carboxymethyl cellulose were added to a ball mill and mixed at 250 r / min for 8 min, then 3000 g of water was added and mixed for 5 min, 80 g of soybean oil and 200 g of glycerol were added and mixed for 10 min, and then added to a molding machine and molded at 25 MPa for 4 min to form a green body, which was sintered in an air atmosphere in a muffle furnace at a heating rate of 3 ° C / min, first heated to 380 ° C, kept warm for 35 min, then heated to 650 ° C, kept warm for 50 min, then heated to 950 ° C, kept warm for 75 min, and finally heated to 1220 ° C, kept warm for 100 min, to obtain the high-strength ceramics using aluminum tailings as raw materials. Example 3

[0045] A method for preparing high-strength ceramics using aluminum tailings as raw materials comprises the following steps:

[0046] (1) Add 2 g of polyethylene glycol to 50 mL of deionized water and dissolve thoroughly. Then add 4 g of vinyl sulfonic acid and stir until completely dissolved. Then, introduce nitrogen to remove oxygen. Slowly add 6 mL of 2 wt% potassium persulfate aqueous solution dropwise within 80 min. Stir and react at 75 °C and 300 rpm for 7 h. Cool the product, freeze-dry it to obtain the modifier, and seal it for storage.

[0047] (2) 0.8 g of the modifier was added to 180 mL of deionized water, and the pH of the system was adjusted to 7 with a dilute sodium hydroxide solution. 10 g of aluminum tailings powder and 1.5 g of zirconium oxide powder were added in sequence at a constant temperature of 50 ° C. The addition process was controlled within 20 min. The mixture was stirred at 50 ° C and 500 r / min for 5 h. After the reaction was completed, the mixture was centrifuged while hot. The product was washed 5 times with 55 ° C hot deionized water and dried to obtain the modified aluminum tailings.

[0048] (3) 4000 g of modified aluminum tailings, 2000 g of diopside, 1500 g of kaolin, 1000 g of silicon nitride whiskers, and 300 g of carboxymethyl cellulose were added to a ball mill and mixed at 250 r / min for 8 min, then 2500 g of water was added and mixed for 5 min, 40 g of soybean oil and 200 g of glycerol were added and mixed for 10 min, and then added to a molding machine and molded at 25 MPa for 4 min to form a green body, which was sintered in an air atmosphere in a muffle furnace at a heating rate of 3 ° C / min, first heated to 380 ° C, kept warm for 35 min, then heated to 650 ° C, kept warm for 50 min, then heated to 950 ° C, kept warm for 75 min, and finally heated to 1220 ° C, kept warm for 100 min, to obtain the high-strength ceramics using aluminum tailings as raw materials. Example 4

[0049] A method for preparing high-strength ceramics using aluminum tailings as raw materials comprises the following steps:

[0050] (1) Add 1 g of polyethylene glycol to 50 mL of deionized water and dissolve it thoroughly. Then add 2 g of vinyl sulfonic acid and stir until it is completely dissolved. Then, introduce nitrogen to remove oxygen. Slowly add 5 mL of 2 wt% potassium persulfate aqueous solution dropwise within 80 min. Stir and react at 70 °C and 300 r / min for 8 h. Cool the product, freeze-dry it to obtain the modifier, and seal it for storage.

[0051] (2) 0.4 g of the modifier was added to 180 mL of deionized water, and the pH of the system was adjusted to 7 with a dilute sodium hydroxide solution. 10 g of aluminum tailings powder and 0.5 g of zirconium oxide powder were added in sequence at a constant temperature of 50 ° C. The addition process was controlled within 20 min. The mixture was stirred at 45 ° C and 500 r / min for 6 h. After the reaction was completed, the mixture was centrifuged while hot. The product was washed 5 times with 55 ° C hot deionized water and dried to obtain the modified aluminum tailings.

[0052] (3) 3000 g of modified aluminum tailings, 1500 g of diopside, 1000 g of kaolin, 500 g of silicon nitride whiskers, and 200 g of carboxymethyl cellulose were added to a ball mill and mixed at 250 r / min for 8 min, then 2000 g of water was added and mixed for 5 min, 20 g of soybean oil and 100 g of glycerol were added and mixed for 10 min, and then added to a molding machine and molded at 25 MPa for 4 min to form a green body, which was sintered in an air atmosphere in a muffle furnace at a heating rate of 3 ° C / min, first heated to 380 ° C, kept warm for 35 min, then heated to 650 ° C, kept warm for 50 min, then heated to 950 ° C, kept warm for 75 min, and finally heated to 1220 ° C, kept warm for 100 min, to obtain the high-strength ceramics using aluminum tailings as raw materials. Comparative Example 1

[0053] A method for preparing high-strength ceramics using aluminum tailings as raw materials comprises the following steps:

[0054] (1) Add 3 g of polyethylene glycol to 50 mL of deionized water and dissolve thoroughly. Then add 8 g of vinyl sulfonic acid and stir until completely dissolved. Then, introduce nitrogen to remove oxygen. Slowly add 10 mL of 2 wt% potassium persulfate aqueous solution dropwise within 80 min. Stir and react at 85 °C and 300 r / min for 5 h. Cool the product, freeze-dry it to obtain the modifier, and seal it for storage.

[0055] (2) 1.6 g of the modifier was added to 180 mL of deionized water, and the pH of the system was adjusted to 7 with a dilute sodium hydroxide solution. 10 g of aluminum tailings powder was added in sequence at a constant temperature of 50 ° C. The addition process was controlled within 20 min. The mixture was stirred at 55 ° C and 500 r / min for 3 h. After the reaction was completed, the mixture was centrifuged while hot. The product was washed 5 times with 55 ° C hot deionized water and dried to obtain the modified aluminum tailings.

[0056] (3) 4500g of modified aluminum tailings, 1500g of zirconium oxide, 3000g of diopside, 2500g of kaolin, 2000g of silicon nitride whiskers and 500g of carboxymethyl cellulose were added to a ball mill and mixed at 250r / min for 8min, then 3500g of water was added and mixed for 5min, 100g of soybean oil and 300g of glycerol were added and mixed for 10min, and then added to a molding machine and molded at 25MPa for 4min to form a green body, which was sintered in an air atmosphere in a muffle furnace at a heating rate of 3°C / min, first heated to 380°C, kept warm for 35min, then heated to 650°C, kept warm for 50min, then heated to 950°C, kept warm for 75min, and finally heated to 1220°C, kept warm for 100min, to obtain the high-strength ceramics using aluminum tailings as raw materials. Comparative Example 2

[0057] A method for preparing high-strength ceramics using aluminum tailings as raw materials comprises the following steps:

[0058] (1) Add 8 g of vinyl sulfonic acid to 50 mL of deionized water and dissolve thoroughly. Stir until completely dissolved and then introduce nitrogen to remove oxygen. Slowly add 10 mL of 2 wt% potassium persulfate aqueous solution dropwise within 80 min. Stir and react at 85 °C and 300 rpm for 5 h. Cool the product, freeze-dry it to obtain the modifier, and seal it for storage.

[0059] (2) 1.6 g of the modifier was added to 180 mL of deionized water, and the pH of the system was adjusted to 7 with a dilute sodium hydroxide solution. 10 g of aluminum tailings powder and 3.5 g of zirconium oxide powder were added in sequence at a constant temperature of 50 ° C. The addition process was controlled within 20 min. The mixture was stirred at 55 ° C and 500 r / min for 3 h. After the reaction was completed, the mixture was centrifuged while hot. The product was washed 5 times with 55 ° C hot deionized water and dried to obtain the modified aluminum tailings.

[0060] (3) 6000 g of modified aluminum tailings, 3000 g of diopside, 2500 g of kaolin, 2000 g of silicon nitride whiskers, and 500 g of carboxymethyl cellulose were added to a ball mill and mixed at 250 r / min for 8 min, then 3500 g of water was added and mixed for 5 min, 100 g of soybean oil and 300 g of glycerol were added and mixed for 10 min, and then added to a molding machine and molded at 25 MPa for 4 min to form a green body, which was sintered in an air atmosphere in a muffle furnace at a heating rate of 3 ° C / min, first heated to 380 ° C, kept warm for 35 min, then heated to 650 ° C, kept warm for 50 min, then heated to 950 ° C, kept warm for 75 min, and finally heated to 1220 ° C, kept warm for 100 min, to obtain the high-strength ceramics using aluminum tailings as raw materials. Comparative Example 3

[0061] A method for preparing high-strength ceramics using aluminum tailings as raw materials comprises the following steps:

[0062] (1) 1.6 g of polyethylene glycol was added to 180 mL of deionized water, and 10 g of aluminum tailings powder and 3.5 g of zirconium oxide powder were added in sequence at a constant temperature of 50 ° C. The addition process was controlled within 20 min, and the mixture was stirred at 55 ° C and 500 r / min for 3 h. After the reaction was completed, the mixture was centrifuged while hot, and the product was washed 5 times with 55 ° C hot deionized water and dried to obtain the modified aluminum tailings;

[0063] (2) 6000 g of modified aluminum tailings, 3000 g of diopside, 2500 g of kaolin, 2000 g of silicon nitride whiskers, and 500 g of carboxymethyl cellulose were added to a ball mill and mixed at 250 r / min for 8 min, then 3500 g of water was added and mixed for 5 min, 100 g of soybean oil and 300 g of glycerol were added and mixed for 10 min, and then added to a molding machine and molded at 25 MPa for 4 min to form a green body, which was sintered in an air atmosphere in a muffle furnace at a heating rate of 3 ° C / min, first heated to 380 ° C, kept warm for 35 min, then heated to 650 ° C, kept warm for 50 min, then heated to 950 ° C, kept warm for 75 min, and finally heated to 1220 ° C, kept warm for 100 min, to obtain the high-strength ceramics using aluminum tailings as raw materials.

[0064] Performance tests were conducted on the ceramics prepared in Examples 1-4 and Comparative Examples 1-3. Deformation and surface flatness of the ceramics were also observed. Samples measuring 40 mm × 4 mm × 3 mm were prepared and tested for flexural strength using the three-point bending method according to GB / T 6569-2006, "Test Method for Flexural Strength of Fine Ceramics," at a loading rate of 0.5 mm / min. Fracture toughness was tested according to GB / T 23806-2009, "Test Method for Fracture Toughness of Fine Ceramics - Single Edge Precracked Beam (SEPB) Method." Porosity was tested according to GB / T 1966-2024, "Porous Ceramics - Determination of Apparent Porosity and Bulk Density." Specific data are shown in Table 1.

[0065] Table 1 High strength ceramic performance test results

[0066]

[0067] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A high-strength ceramic made from aluminum tailings, characterized in that: The invention is prepared from the following components in parts by weight: 30-60 parts of modified aluminum tailings, 15-30 parts of diopside, 10-25 parts of kaolin, 5-20 parts of silicon nitride whiskers, 2-5 parts of carboxymethyl cellulose, 0.2-1 part of soybean oil, 1-3 parts of glycerin, and 20-35 parts of water; The modified aluminum tailings are prepared by the following steps: (1) Add polyethylene glycol to deionized water and fully dissolve it, then add vinyl sulfonic acid, stir until completely dissolved, introduce nitrogen to deoxygenate, slowly add potassium persulfate aqueous solution dropwise, stir to react, cool the product, freeze-dry to obtain the modifier, and seal and store; (2) Add the modifier to deionized water, adjust the pH of the system, add aluminum tailings powder and zirconium oxide powder in sequence at a constant temperature, stir and react, and after the reaction is completed, centrifuge while hot, wash, and dry to obtain the modified aluminum tailings.

2. The high-strength ceramic according to claim 1, characterized in that In step (1), the molecular weight of polyethylene glycol is 800-2000; the concentration of the potassium persulfate aqueous solution is 1-3 wt %; and the dosage ratio of polyethylene glycol, deionized water, vinyl sulfonic acid, and potassium persulfate aqueous solution is 1-3 g:30-60 mL:2-8 g:5-10 mL.

3. The high-strength ceramic according to claim 1, characterized in that In step (1), the potassium persulfate aqueous solution is added dropwise within 60-90 min, and the stirring reaction conditions are 70-85° C. and 200-400 r / min for 5-8 h.

4. The high-strength ceramic according to claim 1, characterized in that In step (2), the dosage ratio of the modifier, deionized water, aluminum tailings powder, and zirconium oxide powder is 0.4-1.6 g: 150-200 mL: 10 g: 0.5-3.5 g.

5. The high-strength ceramic according to claim 1, characterized in that In step (2), the pH of the system is adjusted to 6-8 with a dilute sodium hydroxide solution; aluminum tailings powder and zirconium oxide powder are added in sequence at a constant temperature of 50°C, and the feeding process is controlled within 10-30 minutes; the stirring reaction conditions are 45-55°C and 400-600 r / min for 3-6 hours; and the product is washed 4-6 times with hot deionized water at 50-60°C.

6. The high-strength ceramic according to claim 1, characterized in that In step (2), the particle size of the aluminum tailings powder is 45-75 μm, and the particle size of the zirconium oxide powder is 1-2 μm.

7. The high-strength ceramic according to claim 1, characterized in that The silicon nitride whisker has a diameter of 0.5-1.0 μm and a length of 20-50 μm; the diopside particle size is 70-110 μm; and the kaolin particle size is 800-1250 mesh.

8. A method for preparing high-strength ceramics using aluminum tailings as raw materials according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: adding modified aluminum tailings, diopside, kaolin, silicon nitride whiskers and carboxymethyl cellulose into a ball mill and mixing for 6-9 minutes; then adding water and mixing for 3-6 minutes; adding soybean oil and glycerin and mixing for 8-12 minutes; adding the mixture into a molding machine for molding to form a green body; and sintering the green body to obtain the high-strength ceramic using the aluminum tailings as raw materials.

9. The preparation method according to claim 8, characterized in that The ball mill speed is 200~300r / min; the pressure in the molding machine is 20~30MPa, and the molding time is 3~5min; sintering is carried out in an air atmosphere in a muffle furnace, with a heating rate of 2~3℃ / min, first heating to 350~400℃, keeping warm for 30~40min, then heating to 600~700℃, keeping warm for 40~60min, then heating to 900~1000℃, keeping warm for 60~90min, and finally heating to 1200~1250℃, keeping warm for 90~120min.

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