Process for preparing 95 aluminum oxide ceramic by using dry pressing and granulation powder tailings

Abstract

The invention discloses a process for preparing 95 aluminum oxide ceramic by using dry pressing and granulation powder tailings. The process comprises the following steps: S1, preparing raw materials; s2, performing pretreatment; s3, adding auxiliary materials; s4, mixing and homogenizing treatment; s5, adjusting and refining treatment; s6, granulating and forming; s7, sintering treatment is carried out; and S8, carrying out post-treatment and detection. According to the method, the tailings generated in the processing process are recycled as raw materials, so that resource waste caused by direct discarding of the tailings is avoided, and cyclic utilization of the materials is realized. The tailings are subjected to pretreatment such as sedimentation, ball milling, sieving and iron removal, and a proper amount of aluminum oxide micro powder is added, so that raw material components are uniform and pure; the dry pressing molding and sintering process are combined to ensure the densification of the green body, so that the prepared 95 aluminum oxide ceramic is superior to the traditional prior art in the aspects of voltage resistance, breaking strength, hardness and appearance quality, and the problems of low voltage resistance, surface stripes and the like of the traditional tailing recycled ceramic are avoided.

Description

Technical Field

[0001] This invention relates to the field of alumina ceramic preparation technology, specifically a process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings. Background Technology

[0002] 95% alumina ceramics are high-performance ceramic materials with an aluminum oxide (Al2O3) content of ≥95% as their core characteristic. They have high strength, high hardness, corrosion resistance, high temperature resistance and excellent electrical insulation properties, and are widely used in electronics, electrical appliances, machinery and chemical industries.

[0003] The production and processing of 95% alumina ceramics generates a large amount of powder residue, including recycled materials, scraps, and waste. These residues typically still contain a certain amount of alumina and other impurities, such as silica, light calcium carbonate, kaolin, and small amounts of metal oxides. Traditionally, these residues have been treated as waste, which not only wastes resources but may also increase the environmental burden. With increasing awareness of resource conservation and environmental protection, the effective recycling and reuse of 95% alumina ceramic powder tailings is of great practical significance. However, existing tailings recycling technologies have some problems, such as low voltage resistance of the recycled ceramics, easy appearance of surface blemishes, and insufficient overall density, making it difficult to meet the production requirements of high-quality products.

[0004] Therefore, those skilled in the art have provided a process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings to solve the problems mentioned in the background art. Summary of the Invention

[0005] The purpose of this invention is to provide a process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings includes the following steps: S1. Raw material preparation: Collect the tailings generated during the production and processing of 95% alumina ceramics, including recycled materials, scraps and fallen materials. First, remove floating impurities from the tailings, then perform sedimentation treatment to remove the sinking impurities, and then perform ball milling, sieving and iron removal treatment in sequence to obtain the initial raw materials. S2. Pretreatment: The initial raw material is added to a hydrochloric acid solution with a concentration of 4 mol / L, digested at 70°C for 2 hours, and then filtered to separate the contents, resulting in a solution containing alumina and solid residue. S3. Add auxiliary materials: After the solution containing alumina obtained in step S2 is treated at a high temperature of 800℃~850℃ to generate alumina powder, alumina micro powder is added. S4. Mixing and homogenizing treatment: The mixture obtained in step S3 is mixed and stirred using a stirring device. The stirring speed is controlled at 30-40 rpm and the treatment time is 18-24 hours to ensure that the components are uniformly dispersed and form a stable mixed system. S5. Adjustment and Refining Treatment: The mixed system is subjected to pH adjustment, dilution treatment and grinding and refining treatment in sequence to obtain a refined slurry; S6. Granulation and molding: The refined slurry is granulated to obtain powder, which is then pressed into the required shape by dry pressing to obtain a green body; S7. Sintering treatment: The green body is placed in a high-temperature furnace for sintering. During sintering, the temperature is first raised to 600℃~650℃ and held for 1~2 hours, and then raised to 1450℃~1600℃ for sintering, so that the green body is densified to form 95% alumina ceramic.

[0007] As a further technical solution of the present invention, it also includes post-processing and testing: grinding and polishing the sintered 95% alumina ceramic to improve the surface smoothness, and testing its voltage resistance, flexural strength, hardness and appearance quality to ensure that the product meets the standard requirements.

[0008] As a further technical solution of the present invention, in step S1, the initial raw material composition, by mass percentage, includes 90-93% alumina, 1.5-2% silicon dioxide, 1-2% light calcium carbonate, and 2.5-3% kaolin.

[0009] As a further technical solution of the present invention, in step S3, the added alumina micro powder accounts for 10-30% of the total mass of the initial raw materials in step S1.

[0010] As a further technical solution of the present invention, the specific steps of step S5 are as follows: S51. pH adjustment: Add ammonium citrate to the mixed system as a pH adjuster to adjust the pH value to 8-9; S52. Dilution treatment: Add a diluent to the mixed system after adjusting the pH value to dilute it, so as to improve the dispersibility and flowability of the slurry. S53. Grinding and Refining: After dilution, grind while keeping the iron removal device on until the particle size D is reached. 50 It reaches 4.0–5.0 μm.

[0011] As a further technical solution of the present invention, in step S52, the diluent is oleic acid, and the amount of oleic acid added accounts for 0.5% to 1% of the total mass of the initial raw material in step S1 and the alumina micro powder in step S3.

[0012] As a further technical solution of the present invention, in step S6, the bulk density of the powder is greater than 1.06 g / cm³. 3 The powder contains 60% to 100% particles with a diameter in the range of 60 to 100 μm, has a moisture content of 0.35% to 0.5%, and a loss on ignition of 2% to 3.5%.

[0013] As a further technical solution of the present invention, in step S7, the high-temperature furnace is an electric kiln or a natural gas kiln.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention uses the waste materials (recycled materials, scraps, and fallen materials) generated during the recycling process as raw materials, thus avoiding the waste of resources caused by the direct disposal of waste materials and realizing the recycling of materials.

[0015] (2) The present invention pre-treats the tailings by sedimentation, ball milling, sieving and iron removal, and adds an appropriate amount of alumina powder to make the raw material composition uniform and pure; the dry pressing and sintering process ensures the densification of the green body, so that the 95 alumina ceramics produced are superior to the traditional existing technology in terms of voltage resistance, flexural strength, hardness and appearance quality, and avoids the problems of low voltage resistance and surface blemishes in traditional tailings recycled ceramics.

[0016] (3) This invention reduces raw material costs and energy consumption by recycling tailings and reducing raw material waste, while optimizing the dry pressing and sintering process, and also reduces the potential environmental impact of tailings. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the overall method steps of the present invention; Figure 2 This is a flowchart of the method steps in step S5 of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1 like Figure 1-2 As shown, a process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings includes the following steps: S1. Raw material preparation Collect the tailings generated during the production and processing of 95% alumina ceramics, including recycled materials, scraps, and spilled materials; add the tailings to a settling tank and let them stand to remove floating impurities; after settling, the tailings are successively ball-milled (12 hours), sieved (80μm screen), and iron removed to obtain the initial raw materials; the initial raw materials are composed of the following mass percentages: alumina 92%, silicon dioxide 1.8%, light calcium carbonate 1.5%, and kaolin 2.7%.

[0020] S2, Preprocessing The initial raw material was added to a 4 mol / L hydrochloric acid solution and digested at 70°C for 2 hours. Then, it was filtered and separated to obtain a solution containing alumina and a solid residue.

[0021] S3, Add auxiliary materials After the alumina-containing solution obtained in step S2 is treated at 800°C to generate alumina powder, alumina micro powder is added; the added alumina micro powder accounts for 15% of the total mass of the initial raw materials in step S1.

[0022] S4, Mixing and homogenizing treatment The mixture obtained in step S3 was mixed and stirred using a stirring device at a speed of 35 rpm for 20 hours to ensure that the components were evenly dispersed and formed a stable mixture system.

[0023] S5, Adjustment and Refinement Processing The mixture was subjected to pH adjustment, dilution, and grinding in sequence to obtain a refined slurry. The specific steps are as follows: pH adjustment: Add ammonium citrate to the mixture as a pH adjuster to adjust the pH value to 8.5; Dilution treatment: Oleic acid is added as a diluent to the mixed system after pH adjustment to improve the dispersibility and flowability of the slurry. The amount of oleic acid added accounts for 0.8% of the total mass of the initial raw materials in step S1 and the alumina micro powder in step S3. Grinding and refining: After dilution, grind using grinding equipment, keeping the iron removal device on to avoid the influence of iron on the powder or ceramic properties, until the particle size D is reached. 50 It reaches approximately 4.2 μm.

[0024] S6, Granulation and Molding The refined slurry is granulated to obtain powder, which is then pressed into the desired shape using a dry pressing method to obtain a green body; the powder bulk density is greater than 1.06 g / cm³. 3 The powder contains 80% particles with a diameter in the range of 60 to 100 μm, has a moisture content of 0.4%, and a loss on ignition of 2.5%.

[0025] S7, Sintering treatment The green body is placed in an electric kiln for sintering. During sintering, the temperature is first raised to 620℃ and held for 1 hour, and then raised to 1500℃ for sintering, so that the green body is densified to form 95% alumina ceramic.

[0026] S8, Post-processing and Inspection The sintered 95% alumina ceramic is ground and polished to improve its surface finish, and its voltage resistance, flexural strength, hardness and appearance quality are tested to ensure that the product meets the standard requirements.

[0027] Example 2 A process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings includes the following steps: S1. Raw material preparation Collect the tailings generated during the production and processing of 95% alumina ceramics, including recycled materials, scraps, and fallen materials; add the tailings to a settling tank and let them stand to remove floating impurities; after settling, the tailings are successively ball-milled (10 hours), sieved (100μm screen), and iron removed to obtain the initial raw materials; the initial raw materials are composed of the following mass percentages: 91% alumina, 2% silicon dioxide, 1% light calcium carbonate, and 3% kaolin.

[0028] S2, Preprocessing The initial raw material was added to a 4 mol / L hydrochloric acid solution and digested at 70°C for 2 hours. Then, it was filtered and separated to obtain a solution containing alumina and a solid residue.

[0029] S3, Add auxiliary materials After the alumina-containing solution obtained in step S2 is treated at 850°C to generate alumina powder, alumina micro powder is added; the added alumina micro powder accounts for 25% of the total mass of the initial raw materials in step S1.

[0030] S4, Mixing and homogenizing treatment The mixture obtained in step S3 was mixed and stirred using a stirring device at a speed of 30 rpm for 18 hours to ensure that the components were evenly dispersed and formed a stable mixture system.

[0031] S5, Adjustment and Refinement Processing The mixture was subjected to pH adjustment, dilution, and grinding in sequence to obtain a refined slurry. The specific steps are as follows: pH adjustment: Add ammonium citrate to the mixture as a pH adjuster to adjust the pH value to 8.0; Dilution treatment: Oleic acid is added as a diluent to the mixed system after pH adjustment to improve the dispersibility and flowability of the slurry. The amount of oleic acid added accounts for 0.5% of the total mass of the initial raw materials in step S1 and the alumina micro powder in step S3. Grinding and refining: After dilution, grind using grinding equipment, keeping the iron removal device on to avoid the influence of iron on the powder or ceramic properties, until the particle size D is reached. 50 It reaches approximately 4.5μm.

[0032] S6, Granulation and Molding The refined slurry is granulated to obtain powder, which is then pressed into the desired shape using a dry pressing method to obtain a green body; the powder bulk density is greater than 1.07 g / cm³. 3 The powder contains 70% particles with a diameter in the range of 60 to 100 μm, has a moisture content of 0.35%, and a loss on ignition of 2.8%.

[0033] S7, Sintering treatment The green body is placed in a natural gas kiln for sintering. During sintering, the temperature is first raised to 650℃ and held for 1 hour, and then raised to 1550℃ for sintering, so that the green body is densified to form 95% alumina ceramic.

[0034] S8, Post-processing and Inspection The sintered 95% alumina ceramic is ground and polished to improve its surface finish, and its voltage resistance, flexural strength, hardness and appearance quality are tested to ensure that the product meets the standard requirements.

[0035] Example 3 A process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings includes the following steps: S1. Raw material preparation Collect the tailings generated during the production and processing of 95% alumina ceramics, including recycled materials, scraps, and spilled materials; add the tailings to a settling tank and let them stand to remove floating impurities; after settling, the tailings are successively ball-milled (12 hours), sieved (80μm screen), and iron removed to obtain the initial raw materials; the initial raw materials are composed of the following mass percentages: alumina 90%, silicon dioxide 1.5%, light calcium carbonate 2%, and kaolin 3%.

[0036] S2, Preprocessing The initial raw material was added to a 4 mol / L hydrochloric acid solution and digested at 70°C for 2 hours. Then, it was filtered and separated to obtain a solution containing alumina and a solid residue.

[0037] S3, Add auxiliary materials After the solution containing alumina obtained in step S2 is treated at 820°C to generate alumina powder, alumina micro powder is added; the added alumina micro powder accounts for 20% of the total mass of the initial raw materials in step S1.

[0038] S4, Mixing and homogenizing treatment The mixture obtained in step S3 was mixed and stirred using a stirring device at a speed of 40 rpm for 24 hours to ensure that the components were evenly dispersed and formed a stable mixture system.

[0039] S5, Adjustment and Refinement Processing The mixture was subjected to pH adjustment, dilution, and grinding in sequence to obtain a refined slurry. The specific steps are as follows: pH adjustment: Add ammonium citrate to the mixture as a pH adjuster to adjust the pH value to 8.8; Dilution treatment: Oleic acid is added as a diluent to the mixed system after pH adjustment to improve the dispersibility and flowability of the slurry. The amount of oleic acid added accounts for 1% of the total mass of the initial raw materials in step S1 and the alumina micro powder in step S3. Grinding and refining: After dilution, grind using grinding equipment, keeping the iron removal device on to avoid the influence of iron on the powder or ceramic properties, until the particle size D is reached. 50 It reaches about 5μm.

[0040] S6, Granulation and Molding The refined slurry is granulated to obtain powder, which is then pressed into the desired shape using a dry pressing method to obtain a green body; the powder bulk density is controlled to be greater than 1.08 g / cm³. 3 The powder contains 60% particles with a diameter in the range of 60 to 100 μm, has a moisture content of 0.5%, and a loss on ignition of 3.0%.

[0041] S7, Sintering treatment The green body is placed in an electric kiln for sintering. During sintering, the temperature is first raised to 600°C and held for 1.5 hours, and then raised to 1550°C for sintering, so that the green body is densified to form 95% alumina ceramic.

[0042] S8, Post-processing and Inspection The sintered 95% alumina ceramic is ground and polished to improve its surface finish, and its voltage resistance, flexural strength, hardness and appearance quality are tested to ensure that the product meets the standard requirements.

[0043] Testing revealed that the 95% alumina ceramics prepared in all three examples met the standard requirements for surface smoothness, voltage resistance, flexural strength, and hardness, achieving efficient resource utilization of waste materials. This process reduces both the raw material cost of 95% alumina ceramics and industrial waste emissions, achieving a balance between technological advancement, economic rationality, and environmental benefits, and providing a practical industrialization solution for the green production of 95% alumina ceramics.

[0044] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings, characterized in that, Includes the following steps: S1. Raw material preparation: Collect the tailings generated during the production and processing of 95% alumina ceramics, including recycled materials, scraps and fallen materials. First, remove floating impurities from the tailings, then perform sedimentation treatment to remove the sinking impurities, and then perform ball milling, sieving and iron removal treatment in sequence to obtain the initial raw materials. S2. Pretreatment: The initial raw material is added to a hydrochloric acid solution with a concentration of 4 mol / L, digested at 70°C for 2 hours, and then filtered to separate the contents, resulting in a solution containing alumina and solid residue. S3. Add auxiliary materials: After the solution containing alumina obtained in step S2 is treated at a high temperature of 800℃~850℃ to generate alumina powder, alumina micro powder is added. S4. Mixing and homogenizing treatment: The mixture obtained in step S3 is mixed and stirred using a stirring device. The stirring speed is controlled at 30-40 rpm and the treatment time is 18-24 hours to ensure that the components are uniformly dispersed and form a stable mixed system. S5. Adjustment and Refining Treatment: The mixed system is subjected to pH adjustment, dilution treatment and grinding and refining treatment in sequence to obtain a refined slurry; S6. Granulation and molding: The refined slurry is granulated to obtain powder, which is then pressed into the required shape by dry pressing to obtain a green body; S7. Sintering treatment: The green body is placed in a high-temperature furnace for sintering. During sintering, the temperature is first raised to 600℃~650℃ and held for 1~2 hours, and then raised to 1450℃~1600℃ for sintering, so that the green body is densified to form 95% alumina ceramic.

2. The process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings according to claim 1, characterized in that, It also includes post-processing and testing: grinding and polishing the sintered 95% alumina ceramic to improve surface smoothness, and testing its voltage resistance, flexural strength, hardness and appearance quality to ensure that the product meets the standard requirements.

3. The process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings according to claim 1, characterized in that, In step S1, the initial raw material composition, by mass percentage, includes 90-93% alumina, 1.5-2% silicon dioxide, 1-2% light calcium carbonate, and 2.5-3% kaolin.

4. The process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings according to claim 1, characterized in that, In step S3, the added alumina micro powder accounts for 10-30% of the total mass of the initial raw materials in step S1.

5. The process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings according to claim 1, characterized in that, The specific steps of step S5 are as follows: S51. pH adjustment: Add ammonium citrate to the mixed system as a pH adjuster to adjust the pH value to 8-9; S52. Dilution treatment: Add a diluent to the mixed system after adjusting the pH value to dilute it, so as to improve the dispersibility and flowability of the slurry. S53. Grinding and Refining: After dilution, grind while keeping the iron removal device on until the particle size D is reached. 50 It reaches 4.0–5.0 μm.

6. The process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings according to claim 5, characterized in that, In step S52, the diluent is oleic acid, and the amount of oleic acid added is 0.5% to 1% of the total mass of the initial raw material in step S1 and the alumina micro powder in step S3.

7. The process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings according to claim 1, characterized in that, In step S6, the powder bulk density is greater than 1.06 g / cm³. 3 The powder contains 60% to 100% particles with a diameter in the range of 60 to 100 μm, has a moisture content of 0.35% to 0.5%, and a loss on ignition of 2% to 3.5%.

8. The process for preparing 95% alumina ceramics using dry pressing and granulation powder tailings according to claim 1, characterized in that, In step S7, the high-temperature furnace is an electric kiln or a natural gas kiln.

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