High-strength ceramic taking aluminum tailings as raw material and preparation method of high-strength ceramic

Abstract

The invention discloses high-strength ceramic with aluminum tailings as a raw material and a preparation method of the high-strength ceramic, and the ceramic 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 carboxymethylcellulose, 0.2-1 part of soybean oil, 1-3 parts of glycerol and 20-35 parts of water. According to the invention, a large amount of stockpiled aluminum tailings can be converted into a ceramic product with high added value, the ceramic has the characteristic of light weight while ensuring high mechanical strength, the bending strength and the fracture toughness both reach advanced levels, and the thermal stability and the thermal shock resistance are excellent.

Description

Technical Field

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

[0002] With the rapid development of the aluminum industry in China, the quantity of aluminum tailings generated during the bauxite mining and alumina production processes has increased sharply. According to statistics, approximately 1.5 - 2 tons of aluminum tailings are generated per ton of alumina produced. The annual output of aluminum tailings in China exceeds 60 million tons, and the cumulative stockpile has reached billions of tons.

[0003] As important structural and functional materials, ceramic materials are in great demand in fields such as construction, machinery, electronics, aerospace, etc. Traditional ceramics mainly use natural mineral raw materials such as kaolin, feldspar, quartz, etc. However, with the increasing shortage of high-quality natural raw materials and the rising mining costs, finding alternative raw materials has become an urgent need for the development of the ceramic industry. At the same time, modern industries have higher and higher requirements for the performance of ceramic materials, especially stricter requirements in aspects such as high strength, high toughness, and lightweight. Traditional ceramic materials have difficulty meeting these demands.

[0004] CN112919893A discloses a method for preparing mullite-based composite ceramics by low-temperature sintering using bauxite tailings. Using bauxite tailings, bauxite clinker, and lithium porcelain stone as the main raw materials, mullite-based composite ceramics are prepared through processes such as batching, ball milling, forming, and low-temperature sintering. The mullite-based composite ceramic materials prepared by low-temperature sintering using bauxite tailings have the characteristics of high compressive strength, small linear shrinkage rate, high bulk density, and simple preparation process, and can be used in industries such as the high-value utilization of bauxite tailings and ceramics.

[0005] Existing technologies usually use the method of directly adding or simple pretreatment to use aluminum tailings as ceramic raw materials, but there are the following obvious deficiencies: First, aluminum tailings particles are prone to agglomeration and have poor dispersibility, resulting in uneven ceramic green bodies and affecting the mechanical properties of the final products; second, the interfacial bonding force between aluminum tailings and other raw materials is not strong, and defects are easily generated during the sintering process, restricting the improvement of ceramic strength; third, the strength of ceramic products prepared by existing processes is generally low and difficult to meet the requirements of high-performance applications; finally, there is a lack of effective surface modification technologies and the potential value of aluminum tailings has not been fully exploited.

[0006] Therefore, there is an urgent need to develop a new technical solution. By effectively surface-modifying aluminum tailings, improving their dispersibility and interfacial bonding properties, and through scientific formula design and process optimization, high-strength and high-toughness ceramic materials are prepared, which not only solves the comprehensive utilization problem of aluminum tailings but also meets 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: 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.

[0009] Preferably, the modified aluminum tailings are prepared by the following method 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; 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.

[0010] 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.

[0011] 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.

[0012] (2) Add the modifier to deionized water, adjust the pH of the system, and sequentially add aluminum tailings powder and zirconia powder at a constant temperature, stir and react. After the reaction is completed, centrifuge, wash, and dry while it is still hot to obtain the modified aluminum tailings.

[0013] Surface coordination modification: After the modifier is dissolved, the system is strongly acidic. Adjust it to pH 6 - 8 with a base. At this time, part of the sulfonic acid groups are ionized into ions. At the same time, the appropriate pH conditions make the metal ions ( , , etc.) on the surface of aluminum tailings and zirconia in a hydrated but not fully hydroxylated active state. The polymer modifier is adsorbed onto the mineral surface through various interactions: The sulfonic acid groups form coordination bonds with the surface metal ions, and the ether oxygen atoms in the polyethylene glycol segments can also have weak coordination with the metal ions. The polymer long 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.

[0014] Preferably, in step (2), the dosage ratio of the modifier, deionized water, aluminum tailings powder, and zirconia powder is 0.4 - 1.6 g : 150 - 200 mL : 10 g : 0.5 - 3.5 g.

[0015] Preferably, in step (2), adjust the pH of the system to 6 - 8 with dilute sodium hydroxide solution; sequentially add aluminum tailings powder and zirconia powder at a constant temperature of 50 °C, and control the feeding process within 10 - 30 min; the stirring reaction conditions are stirring at 45 - 55 °C and 400 - 600 r / min for 3 - 6 h; wash the product 4 - 6 times with hot deionized water at 50 - 60 °C.

[0016] Preferably, in step (2), the particle size of the aluminum tailings powder is 45 - 75 µm, and the particle size of the zirconia powder is 1 - 2 µm.

[0017] Preferably, the diameter of the silicon nitride whiskers is 0.5 - 1.0 µm, and the length is 20 - 50 µm; the particle size of the diopside is 70 - 110 µm; the particle size of the kaolin is 800 - 1250 mesh.

[0018] Preferably, the aluminum tailings are bauxite tailings, with the main components being 30 - 50 wt% alumina, 25 - 45% silica, 1 - 10 wt% iron oxide, 0.3 - 10 wt% titanium dioxide, and other impurities not exceeding 10 wt%.

[0019] The present invention also claims to protect a preparation method for the high-strength ceramics using the aluminum tailings as raw materials, which includes the following steps: adding the modified aluminum tailings, diopside, kaolin, silicon nitride whiskers, and carboxymethyl cellulose into a ball mill for mixing for 6 - 9 minutes, then adding water for mixing for 3 - 6 minutes, adding soybean oil and glycerol for mixing for 8 - 12 minutes, and adding them into a molding press for molding to form a green body, and sintering to obtain the high-strength ceramics using the aluminum tailings as raw materials.

[0020] Preferably, the rotation speed of the ball mill is 200 - 300 r / min; the pressure in the molding press is 20 - 30 MPa, and the molding time is 3 - 5 minutes; sintering is carried out in an air atmosphere in a muffle furnace. With a heating rate of 2 - 3 °C / min, first heat up to 350 - 400 °C, keep warm for 30 - 40 minutes, then heat up to 600 - 700 °C, keep warm for 40 - 60 minutes, then heat up to 900 - 1000 °C, keep warm for 60 - 90 minutes, and finally heat up to 1200 - 1250 °C, keep warm for 90 - 120 minutes.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a kind of high-strength ceramics using aluminum tailings as raw materials. The modified aluminum tailings are used as the main base material, realizing the comprehensive utilization and high-value conversion of aluminum tailings. After surface functionalization treatment, they have excellent dispersibility and interfacial bonding ability, providing a solid structural foundation for the ceramics; diopside has excellent high-temperature stability and low thermal expansion coefficient, which can improve the sintering densification process of the ceramics and enhance the thermal shock stability of the material; kaolin, as a classic ceramic raw material, forms mullite phase during the sintering process, significantly improving the mechanical strength of the ceramics. At the same time, its good plasticity is beneficial to the forming of the green body; silicon nitride whiskers, as a high-performance reinforcing phase, its unique fibrous structure can effectively prevent crack propagation, and greatly improve the fracture toughness and flexural strength of the ceramics through toughening mechanisms such as pulling out and bridging; carboxymethyl cellulose, as an environmentally friendly organic binder, provides sufficient green body strength at low temperature and completely decomposes without leaving residues at high temperature; soybean oil and glycerol are used as natural lubricants and plasticizers respectively, significantly improving the rheological properties and forming properties of the ceramic slurry. The iron and titanium elements in the aluminum tailings can promote the formation of high-temperature melt, reduce the sintering temperature, which is beneficial to energy conservation, emission reduction and cost reduction. The overall formula of the present invention achieves a perfect balance among strength, toughness, formability and economy, and at the same time realizes the high-value utilization of aluminum tailings, reducing problems such as land occupation and environmental pollution caused by aluminum tailings.

[0022] 2. The present invention provides a modified aluminum tailings. The modifier undergoes coordination and other interactions with the surfaces of aluminum tailings powder and zirconia powder. A large number of sulfonic acid functional groups in the modifier molecules can make the powder surface negatively charged. Through the steric hindrance mechanism and the electrostatic repulsion mechanism, the slurry is uniformly dispersed, significantly improving the dispersibility of the powder, reducing the agglomeration phenomenon, and improving the uniformity and density of the ceramic. The modifier also has dual functional characteristics: it acts as a dispersant to improve the particle dispersibility and as a pore-forming agent to undergo pyrolysis during high-temperature sintering, leaving a rich and uniform pore structure in the ceramic. This enables the prepared ceramic to maintain excellent flexural strength while having a relatively high porosity, achieving the organic unity of light weight and high strength. The introduced zirconium element in the modified aluminum tailings forms an alumina-zirconia composite system with alumina in the base material, which can greatly enhance the mechanical strength of the ceramic, thereby obtaining a truly high-strength ceramic. The modifier constructs a three-dimensional network structure between ceramic particles, providing the necessary strength and toughness for the ceramic, ensuring the shape stability of the green body during the processing, and helping to obtain ceramic products with better mechanical properties. This modification method converts the originally difficult-to-directly-use aluminum tailings into high-value-added ceramic raw materials, not only solving the environmental pollution problem of aluminum tailings but also providing new raw materials with excellent properties for the ceramic industry. The process has strong adaptability, can achieve densification at a relatively low sintering temperature, and reduces energy consumption. Detailed Embodiments

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with embodiments. Of course, the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased through market channels or synthesized from raw materials purchased through market channels.

[0025] The polyethylene glycol is PEG-1000; The zirconia, with a purity of 99.5% and an average particle size of 1.5 μm, is purchased from Hangzhou Zhitai Purification Technology Co., Ltd., and the model is VK-R55; The kaolin is triclinic, with a specific surface area of 10 m 2 / g, and is purchased from Shijiazhuang Tourmaline Mineral Products Co., Ltd.

[0026] A method for preparing a high-strength ceramic using aluminum tailings as a raw material, comprising the following steps: (1) Add 1 - 3 g of polyethylene glycol to 30 - 60 mL of deionized water and dissolve it completely. Then add 2 - 8 g of vinylsulfonic acid. After stirring until completely dissolved, purge with nitrogen to remove oxygen. Slowly add dropwise 5 - 10 mL of 1 - 3 wt% potassium persulfate aqueous solution, and finish the addition within 60 - 90 min. Stir and react at 70 - 85 °C and 200 - 400 r / min for 5 - 8 h. Cool the product and freeze-dry to obtain the modifier, and store it sealed. (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 dilute sodium hydroxide solution. At a constant temperature of 50 °C, add 10 g of aluminum tailings powder and 0.5 - 3.5 g of zirconia powder in sequence. Control the feeding process within 10 - 30 min. Stir and react at 45 - 55 °C and 400 - 600 r / min for 3 - 6 h. After the reaction, centrifuge while it is hot. Wash the product 4 - 6 times with hot deionized water at 50 - 60 °C, and dry it to obtain the modified aluminum tailings. (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 min. Then add 20 - 35 parts of water and mix for 3 - 6 min. Add 0.2 - 1 part of soybean oil and 1 - 3 parts of glycerol and mix for 8 - 12 min. Add it into a molding press and mold at 20 - 30 MPa for 3 - 5 min to make a green body. Sinter it in a muffle furnace under an air atmosphere. At a heating rate of 2 - 3 °C / min, first heat up to 350 - 400 °C and hold for 30 - 40 min, then heat up to 600 - 700 °C and hold for 40 - 60 min, then heat up to 900 - 1000 °C and hold for 60 - 90 min, and finally heat up to 1200 - 1250 °C and hold for 90 - 120 min to obtain the high-strength ceramic using aluminum tailings as raw material.

[0027] The following is a further description of the present invention through specific examples. Example 1

[0028] A preparation method of a high-strength ceramic using aluminum tailings as raw material, comprising the following steps: (1) Add 3 g of polyethylene glycol to 50 mL of deionized water and dissolve it completely. Then add 8 g of vinylsulfonic acid. After stirring until completely dissolved, purge with nitrogen to remove oxygen. Slowly add dropwise 10 mL of 2 wt% potassium persulfate aqueous solution, and finish the addition within 80 min. Stir and react at 85 °C and 300 r / min for 5 h. Cool the product and freeze-dry to obtain the modifier, and store it sealed. (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. (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

[0029] A method for preparing high-strength ceramics using aluminum tailings as raw materials comprises the following steps: (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. (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. (3) Add 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 into a ball mill and mix at 250 r / min for 8 min. Then add 3000 g of water and mix for 5 min. Add 80 g of soybean oil and 200 g of glycerol and mix for 10 min. Then add the mixture into a molding press and press at 25 MPa for 4 min to form a green body. Sinter the green body in a muffle furnace under an air atmosphere. With a heating rate of 3 °C / min, first heat up to 380 °C and hold for 35 min, then heat up to 650 °C and hold for 50 min, then heat up to 950 °C and hold for 75 min, and finally heat up to 1220 °C and hold for 100 min to obtain the high-strength ceramic using aluminum tailings as raw material. Example 3

[0030] A preparation method of a high-strength ceramic using aluminum tailings as raw material, comprising the following steps: (1) Add 2 g of polyethylene glycol into 50 mL of deionized water and dissolve it completely. Then add 4 g of vinylsulfonic acid, stir until completely dissolved, and then pass nitrogen to remove oxygen. Slowly dropwise add 6 mL of 2 wt% potassium persulfate aqueous solution, and finish dropping within 80 min. Stir and react at 75 °C and 300 r / min for 7 h. Cool the product and freeze-dry to obtain a modifier, and store it sealed. (2) Add 0.8 g of the modifier into 180 mL of deionized water, adjust the pH of the system to 7 with dilute sodium hydroxide solution, and sequentially add 10 g of aluminum tailings powder and 1.5 g of zirconia powder at a constant temperature of 50 °C. Control the feeding process within 20 min, stir and react at 50 °C and 500 r / min for 5 h. After the reaction, centrifuge while it is hot, wash the product 5 times with hot deionized water at 55 °C, and dry it to obtain the modified aluminum tailings. (3) Add 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 into a ball mill and mix at 250 r / min for 8 min. Then add 2500 g of water and mix for 5 min. Add 40 g of soybean oil and 200 g of glycerol and mix for 10 min. Then add the mixture into a molding press and press at 25 MPa for 4 min to form a green body. Sinter the green body in a muffle furnace under an air atmosphere. With a heating rate of 3 °C / min, first heat up to 380 °C and hold for 35 min, then heat up to 650 °C and hold for 50 min, then heat up to 950 °C and hold for 75 min, and finally heat up to 1220 °C and hold for 100 min to obtain the high-strength ceramic using aluminum tailings as raw material. Example 4

[0031] A preparation method of a high-strength ceramic using aluminum tailings as raw material, comprising the following steps: (1) Add 1 g of polyethylene glycol to 50 mL of deionized water and dissolve it thoroughly. Then add 2 g of vinylsulfonic acid. After stirring until completely dissolved, pass nitrogen to remove oxygen. Slowly dropwise add 5 mL of 2 wt% potassium persulfate aqueous solution and finish dropping within 80 min. Stir and react at 70 °C and 300 r / min for 8 h. Cool the product and freeze-dry to obtain the modifier, and store it sealed. (2) Add 0.4 g of the modifier to 180 mL of deionized water. Adjust the pH of the system to 7 with dilute sodium hydroxide solution. At a constant temperature of 50 °C, sequentially add 10 g of aluminum tailings powder and 0.5 g of zirconia powder. Control the feeding process within 20 min. Stir and react at 45 °C and 500 r / min for 6 h. After the reaction, centrifuge while it is hot. Wash the product 5 times with hot deionized water at 55 °C and dry it to obtain the modified aluminum tailings. (3) Add 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 to a ball mill and mix at 250 r / min for 8 min. Then add 2000 g of water and mix for 5 min. Add 20 g of soybean oil and 100 g of glycerol and mix for 10 min. Add it to a molding press and mold at 25 MPa for 4 min to form a green body. Sinter it in a muffle furnace under an air atmosphere. At a heating rate of 3 °C / min, first heat up to 380 °C and hold for 35 min, then heat up to 650 °C and hold for 50 min, then heat up to 950 °C and hold for 75 min, and finally heat up to 1220 °C and hold for 100 min to obtain the high-strength ceramic using aluminum tailings as raw material. Comparative Example 1

[0032] A preparation method of a high-strength ceramic using aluminum tailings as raw material, comprising the following steps: (1) Add 3 g of polyethylene glycol to 50 mL of deionized water and dissolve it thoroughly. Then add 8 g of vinylsulfonic acid. After stirring until completely dissolved, pass nitrogen to remove oxygen. Slowly dropwise add 10 mL of 2 wt% potassium persulfate aqueous solution and finish dropping within 80 min. Stir and react at 85 °C and 300 r / min for 5 h. Cool the product and freeze-dry to obtain the modifier, and store it sealed. (2) Add 1.6 g of the modifier to 180 mL of deionized water. Adjust the pH of the system to 7 with dilute sodium hydroxide solution. At a constant temperature of 50 °C, sequentially add 10 g of aluminum tailings powder. Control the feeding process within 20 min. Stir and react at 55 °C and 500 r / min for 3 h. After the reaction, centrifuge while it is hot. Wash the product 5 times with hot deionized water at 55 °C and dry it to obtain the modified aluminum tailings. (3) Add 4500 g of modified aluminum tailings, 1500 g of zirconia, 3000 g of diopside, 2500 g of kaolin, 2000 g of silicon nitride whiskers, and 500 g of carboxymethyl cellulose into a ball mill and mix at 250 r / min for 8 min. Then add 3500 g of water and mix for 5 min. Add 100 g of soybean oil and 300 g of glycerol and mix for 10 min. Add the mixture into a molding press and press at 25 MPa for 4 min to form a green body. Sinter the green body in a muffle furnace under an air atmosphere. With a heating rate of 3 °C / min, first heat up to 380 °C and hold for 35 min, then heat up to 650 °C and hold for 50 min, then heat up to 950 °C and hold for 75 min, and finally heat up to 1220 °C and hold for 100 min to obtain the high-strength ceramic made from aluminum tailings. Comparative Example 2

[0033] A preparation method of a high-strength ceramic made from aluminum tailings, comprising the following steps: (1) Add 8 g of vinylsulfonic acid into 50 mL of deionized water and dissolve it fully. After stirring until completely dissolved, introduce nitrogen to remove oxygen, and slowly dropwise add 10 mL of 2 wt% potassium persulfate aqueous solution, which is added dropwise within 80 min. Stir and react at 85 °C and 300 r / min for 5 h. Cool the product and freeze-dry it to obtain a modifier, which is stored in a sealed manner. (2) Add 1.6 g of the modifier into 180 mL of deionized water, adjust the pH of the system to 7 with dilute sodium hydroxide solution, and sequentially add 10 g of aluminum tailings powder and 3.5 g of zirconia powder at a constant temperature of 50 °C. The feeding process is controlled within 20 min. Stir and react at 55 °C and 500 r / min for 3 h. After the reaction, centrifuge while it is hot, wash the product 5 times with hot deionized water at 55 °C, and dry it to obtain the modified aluminum tailings. (3) Add 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 into a ball mill and mix at 250 r / min for 8 min. Then add 3500 g of water and mix for 5 min. Add 100 g of soybean oil and 300 g of glycerol and mix for 10 min. Add the mixture into a molding press and press at 25 MPa for 4 min to form a green body. Sinter the green body in a muffle furnace under an air atmosphere. With a heating rate of 3 °C / min, first heat up to 380 °C and hold for 35 min, then heat up to 650 °C and hold for 50 min, then heat up to 950 °C and hold for 75 min, and finally heat up to 1220 °C and hold for 100 min to obtain the high-strength ceramic made from aluminum tailings. Comparative Example 3

[0034] A preparation method of a high-strength ceramic made from aluminum tailings, comprising the following steps: (1) Add 1.6 g of polyethylene glycol to 180 mL of deionized water. Sequentially add 10 g of aluminum tailings powder and 3.5 g of zirconia powder at a constant temperature of 50 °C. Control the feeding process within 20 min. Stir and react at 55 °C and 500 r / min for 3 h. After the reaction, centrifuge while it is hot. Wash the product 5 times with hot deionized water at 55 °C, and then dry it to obtain the modified aluminum tailings. (2) Add 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 into a ball mill and mix at 250 r / min for 8 min. Then add 3500 g of water and mix for 5 min. Add 100 g of soybean oil and 300 g of glycerol and mix for 10 min. Then add the mixture into a molding press and mold it at 25 MPa for 4 min to form a green body. Sinter it in a muffle furnace under an air atmosphere. With a heating rate of 3 °C / min, first heat it to 380 °C and hold for 35 min, then heat it to 650 °C and hold for 50 min, then heat it to 950 °C and hold for 75 min, and finally heat it to 1220 °C and hold for 100 min to obtain the high-strength ceramic using aluminum tailings as the raw material.

[0035] Perform performance tests on the ceramics prepared in Examples 1 - 4 and Comparative Examples 1 - 3. At the same time, observe whether the shape of the ceramics is deformed and the surface flatness. Make the ceramics into specimens with dimensions of 40 mm × 4 mm × 3 mm. Refer to GB / T 6569 - 2006 "Test Method for Flexural Strength of Fine Ceramics" and use the three-point bending method to test the flexural strength of the samples, with a loading rate of 0.5 mm / min; refer to GB / T 23806 - 2009 "Test Method for Fracture Toughness of Fine Ceramics - Single Edge Pre-Cracked Beam (SEPB) Method" to test the fracture toughness of the ceramics; refer to GB / T 1966 - 2024 "Determination of Apparent Porosity and Bulk Density of Porous Ceramics" to test the porosity of the ceramics. The specific data are shown in Table 1.

[0036] Table 1 Test Results of the Performance of High-Strength Ceramics

[0037] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope 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.

2. The high-strength ceramic according to claim 1, characterized in that, 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.

3. The high-strength ceramic according to claim 2, wherein, 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.

4. The high-strength ceramic according to claim 2, wherein 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.

5. The high-strength ceramic according to claim 2, 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.

6. The high-strength ceramic according to claim 2, wherein 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.

7. The high-strength ceramic according to claim 2, wherein 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.

8. 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.

9. A preparation method for preparing high-strength ceramics using aluminum tailings as raw materials as described in any one of claims 1 to 8, 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.

10. The preparation method according to claim 9, characterized in that, The rotational speed of the ball mill is 200 - 300 r / min; the pressure in the molding press is 20 - 30 MPa, and the molding time is 3 - 5 min; sintering is carried out in a muffle furnace under an air atmosphere, with a heating rate of 2 - 3 °C / min. First, it is heated to 350 - 400 °C and held for 30 - 40 min, then heated to 600 - 700 °C and held for 40 - 60 min, then heated to 900 - 1000 °C and held for 60 - 90 min, and finally heated to 1200 - 1250 °C and held for 90 - 120 min.

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