Method for producing composite bauxite

Abstract

The invention relates to a method for producing composite bauxite, which comprises the following steps: S1, pretreating and proportioning raw materials; s2, carrying out dry-method co-grinding and homogenization; s3, carrying out dry granulation and molding; s4, step-type heating sintering is carried out; the method for producing the composite bauxite comprises a series of collaborative optimization steps of accurate pretreatment and proportioning of raw materials, wet-process co-grinding homogenization, spray granulation and forming, stepped heating sintering and aftertreatment performance regulation. According to the invention, highly uniform compounding and strong interface bonding of bauxite and various functional additives on a micro scale are realized, and the problems of non-uniform component dispersion, many interface defects and functional component volatilization or structure deterioration caused by a high-temperature process in the prior art are effectively overcome.

Description

Technical Field

[0001] This application relates to the field of bauxite preparation technology, and in particular to a method for producing composite bauxite. Background Technology

[0002] With the continuous growth in demand for high-performance inorganic non-metallic materials from modern industry, bauxite, due to its excellent high-temperature resistance, chemical stability, and mechanical strength, has become a key basic raw material in refractory materials, metallurgy, chemical industry, and ceramics. However, the single composition and limited performance of natural bauxite make it difficult to meet the comprehensive requirements of multifunctional integration in high-end applications—for example, high refractoriness, thermal shock resistance, and volume stability are required simultaneously in high-temperature furnace linings, while higher standards are placed on purity, particle size distribution, and functional compositeness in catalysis or precision ceramics. This necessitates an urgent shift in the industry from single minerals to composite functional materials to overcome the performance bottlenecks of natural resources.

[0003] The development of composite bauxite focuses on achieving synergistic improvement in material performance through the introduction of functional components and optimization of preparation processes. Its core objective is to construct a novel bauxite system with high stability, strong interfacial bonding, and controllable functional properties, thereby expanding its applicability under harsh operating conditions. However, existing composite modification technologies still face multiple constraints: on the one hand, additives such as magnesium oxide and silicon carbide have poor compatibility with the bauxite matrix, easily leading to uneven dispersion and increased interfacial defects, significantly weakening the overall mechanical and thermal properties of the material; on the other hand, mainstream high-temperature sintering or melt composite processes are energy-intensive and time-consuming, and easily cause the volatilization of functional components or structural deterioration, making it difficult to ensure the controllability and consistency of the composite effect.

[0004] Furthermore, current composite formulations largely rely on trial and error, lacking a systematic design based on the physicochemical matching mechanism between components, making it difficult to unleash the synergistic effect of performance. Simultaneously, for the utilization of low- and medium-grade bauxite, existing technologies generally suffer from low purification efficiency, high impurity residues, and limited added value enhancement, resulting in both resource waste and cost pressure. These shortcomings collectively make it difficult for existing production methods to simultaneously achieve composite uniformity, process economy, and resource sustainability, severely restricting the large-scale application of high-performance composite bauxite. Therefore, a method for producing composite bauxite is needed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for producing a novel composite refractory clay, so as to solve the technical problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for producing composite bauxite, comprising the following steps:

[0007] S1: Raw material pretreatment and batching: Select bauxite ore for crushing and screening, control the particle size distribution range to 0.1 mm to 5 mm, and accurately measure the functional additive components according to the target composite performance requirements, including magnesium oxide, silicon carbide and rare earth oxides, with the mass percentage error of each component controlled within ±0.5%.

[0008] S2: Dry co-grinding and homogenization: Based on the particle size requirements of production, select one of ball mill, vertical mill or Raymond mill as the grinding equipment, put the pretreated bauxite and functional additives into the selected grinding equipment, and use appropriate grinding media and grinding methods to achieve material refinement and mixing to ensure that the preset particle size standard is met.

[0009] S3: Dry granulation and molding: A dry composite binder is added to the uniform powder. The binder is a mixture of modified starch powder and nano-silica powder, and the addition amount is 4% to 8% of the total powder mass. The powder is mixed for 10 to 20 minutes at a speed of 60 to 100 rpm using a high-power mixer to obtain a uniform and plastic powder. The powder is then pressed into spherical granules by a roller granulator, and then pressed into green bodies by a hydraulic press or isostatic press at a pressure of 50 MPa to 100 MPa and a holding time of 30 to 60 seconds.

[0010] S4: Stepped Temperature Sintering: The green blanks are placed in a high-temperature sintering furnace and sintered using a multi-stage temperature control program. The first stage raises the temperature from room temperature to 600 degrees Celsius at a rate of 5 degrees Celsius per minute and holds for 30 minutes. The second stage raises the temperature to 1200 degrees Celsius at a rate of 3 degrees Celsius per minute and holds for 1 hour. The third stage raises the temperature to 1550 to 1650 degrees Celsius at a rate of 2 degrees Celsius per minute and holds for 2 to 4 hours. The sintering atmosphere is a mixture of nitrogen and argon, with nitrogen comprising 70% to 90% of the gas. The furnace is maintained at a slightly positive pressure of 100 to 500 Pa above atmospheric pressure.

[0011] S5: Post-processing and performance control: Forced air cooling or controlled slow cooling is applied to the sintered body, with the cooling rate adjusted to the range of 10 degrees Celsius to 50 degrees Celsius per minute. Subsequently, the cooled composite bauxite products undergo surface finishing and non-destructive testing to ensure that the dimensional tolerance is within ±0.1 mm and that there are no macroscopic defects inside.

[0012] Preferably, the bauxite ore in S1 is a medium-to-low grade bauxite with an alumina content of 45% to 65%, an iron oxide content of less than or equal to 5%, and a silicon oxide content of 10% to 25%. After crushing and screening, a strong magnetic separator is used to remove magnetic impurities with a magnetic field strength of 1.0 Tesla to 1.5 Tesla, so that the residual iron oxide content in the non-magnetic product is reduced to below 2%.

[0013] Preferably, the dosage of the functional additives in S1 is based on the ratio of the chemical composition of the bauxite matrix to the target composite phase composition. The amount of magnesium oxide added is 3% to 8% of the mass of bauxite, the amount of silicon carbide added is 5% to 12% of the mass of bauxite, and the rare earth oxides are selected from one or a combination of cerium oxide or lanthanum oxide, and the amount added is 0.5% to 2% of the mass of bauxite.

[0014] Preferably, in the S3 dry composite binder, the mass ratio of modified starch powder to nano silica powder is 3:1 to 5:1, and both are pulverized by airflow to a particle size ≤5 micrometers; the roller surface of the roller granulator has a semi-circular groove, the roller spacing is adjustable from 0.5 mm to 2 mm, the spherical particle size is 2 mm to 5 mm, and the angle of repose is ≤30 degrees.

[0015] Preferably, when an isostatic press is used for pressing in S3, the mold for encapsulating the green blank is made of an elastic polymer material, the pressing medium is a water-based emulsion, the density of the green blank reaches 55% to 60% of the theoretical density, and the coefficient of variation of density distribution uniformity is less than 5%.

[0016] Preferably, the S4 high-temperature sintering furnace has a full fiber-lined structure and is equipped with a high-precision temperature control system and an atmosphere analyzer. The temperature control accuracy is ±3 degrees Celsius, and the atmosphere analyzer can monitor the oxygen content and gas composition inside the furnace in real time.

[0017] Preferably, in S4, during the third stage of sintering and heat preservation, an intermittent pressure-assisted sintering mechanism is introduced, applying axial mechanical pressure of 10 MPa for a duration of 5 minutes at the 30th, 60th, and 90th minutes after the start of heat preservation.

[0018] Preferably, in step S5, the forced air cooling employs a multi-segment controllable wind speed cooling device. The cooling air temperature starts at 200 degrees Celsius, and the wind speed is gradually distributed along the length of the product, with the highest wind speed zone having a wind speed of 8 meters per second and the lowest wind speed zone having a wind speed of 2 meters per second, to ensure uniform release of internal thermal stress and prevent cracking. Non-destructive testing employs a dual inspection system combining ultrasonic flaw detection and real-time X-ray imaging. The ultrasonic frequency is 5 MHz, and the X-ray tube voltage is 160 kV with a current of 5 mA.

[0019] Preferably, the feature is that it further includes establishing a product performance database, and using a multiple regression analysis model based on the database to optimize the batching scheme and sintering process for subsequent production, with a product performance prediction accuracy rate of more than 90%.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] Through a series of synergistic optimization steps, including precise pretreatment and batching of raw materials, wet co-milling and homogenization, spray granulation, stepped heating sintering, and post-treatment performance control, ball mills, vertical mills, or Raymond mills are flexibly selected for dry co-milling operations based on the required particle size. This adapts to different particle size requirements and production scenarios, utilizing the grinding characteristics of the corresponding equipment to achieve highly uniform composite and strong interfacial bonding of bauxite and various functional additives at the microscale. This effectively overcomes the problems of uneven component dispersion, numerous interfacial defects, and volatilization or structural deterioration of functional components caused by high-temperature processes in existing technologies. At the same time, this method is particularly suitable for the efficient utilization of low- and medium-grade bauxite resources. Through integrated process control and non-destructive testing, it significantly improves the overall performance consistency, process economy, and resource utilization rate of composite bauxite products, meeting the stringent requirements of high-end application scenarios for material refractoriness, thermal shock resistance, volume stability, and functional compositeness. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the steps of the present invention. Detailed Implementation

[0023] 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.

[0024] refer to Figure 1 A method for producing composite bauxite comprises five core steps, forming a tightly coupled, parameter-linked closed-loop control system to ensure that the final product meets design specifications in terms of microstructure, macroscopic properties, and dimensional accuracy. Specifically, the method includes the following steps:

[0025] S1: Raw material pretreatment and batching;

[0026] S2: Dry co-milling and homogenization;

[0027] S3: Dry granulation and molding;

[0028] S4: Stepped heating sintering;

[0029] S5: Post-processing and performance tuning.

[0030] Specifically, S1: Raw material pretreatment and batching: Select bauxite ore for crushing and screening, control the particle size distribution range to 0.1 mm to 5 mm, and accurately measure the functional additive components, including magnesium oxide, silicon carbide and rare earth oxides, according to the target composite performance requirements. The mass percentage error of each component is controlled within ±0.5%.

[0031] It should be noted that the bauxite ore is of medium to low grade, with an alumina content of 45% to 65%, an iron oxide content of less than or equal to 5%, and a silicon oxide content of 10% to 25%. After crushing and screening, a high-intensity magnetic separator is used to remove magnetic impurities. The magnetic field strength is 1.0 Tesla to 1.5 Tesla. Through the action of the high gradient magnetic field, iron-containing magnetic impurities (such as hematite and magnetite particles) are effectively captured and removed, reducing the residual iron oxide content in the non-magnetic products to below 2%. This significantly reduces the risk of liquid phase formation and grain boundary weakening caused by iron impurities during sintering.

[0032] The dosage of functional additives is precisely proportioned based on the chemical composition of the bauxite matrix and the target composite phase. The amount of magnesium oxide added is 3% to 8% of the bauxite mass. Its main function is to react with alumina in the bauxite during the subsequent sintering process to form a magnesium aluminum spinel phase. This phase has a high melting point, low coefficient of thermal expansion and good elastic modulus, which can effectively buffer thermal stress and enhance the thermal shock resistance of the material. The amount of silicon carbide added is 5% to 12% of the bauxite mass. Its high thermal conductivity can accelerate heat transfer and reduce local temperature differences. At the same time, its high hardness and chemical inertness significantly improve the wear resistance and corrosion resistance of the material. Rare earth oxides are selected from one or a combination of two of cerium oxide or lanthanum oxide, and the amount added is 0.5% to 2% of the bauxite mass. Rare earth ions segregate at the grain boundaries at high temperatures, which can pin the grain boundaries, inhibit abnormal grain growth and purify the grain boundaries, thereby refining the microstructure and improving the density and mechanical strength of the material. This formulation method is based on precise proportions calculated using thermodynamic and kinetic methods to determine the chemical composition of the bauxite matrix and the target composite phase. This ensures that each functional component reacts along the expected path and forms a stable composite phase during sintering.

[0033] S2: Based on the required particle size for production, select one of a ball mill, vertical mill, or Raymond mill as the grinding equipment. Add the pretreated bauxite and functional additives to the selected grinding equipment. No water is needed. Add 0.1% to 0.5% of a powdered polycarboxylate dispersant by weight of the total solids. The grinding principle of the corresponding equipment will be used to refine and mix the particles, ensuring that the preset particle size standard is met. Details are as follows:

[0034] When selecting a ball mill: use zirconia grinding balls as the grinding media. The material is refined through the impact, collision and grinding action of the grinding balls. The grinding speed is 40 to 80 revolutions per minute, and the grinding time is 2 to 4 hours. It is equipped with a built-in classifying sieve and a back-blowing device. The aperture of the classifying sieve can be adjusted within the range of 0.075 mm to 0.2 mm. Unqualified coarse particles are returned to the grinding chamber for re-grinding through the back-blowing device. During the grinding process, circulating cooling water is introduced through the mill jacket to control the powder temperature ≤80 degrees Celsius. Finally, uniform powder with a median particle size distribution of 5 micrometers to 15 micrometers is obtained.

[0035] When selecting a vertical mill: Zirconia liners and zirconia grinding rollers are used as grinding media. The material forms a stable bed between the grinding rollers and the grinding disc, and is refined through high-pressure extrusion and shearing. The grinding pressure is 8 MPa to 15 MPa, the grinding air velocity is 1.2 m to 2.0 m per second, and the grinding time is 1.5 hours to 3 hours. It is equipped with a built-in high-efficiency classifier with a speed of 1500 to 2500 rpm. The particle size distribution is controlled by adjusting the speed of the classifier. During the grinding process, cooling air is introduced through the mill housing jacket, which, together with the hot air exhaust port at the top of the grinding chamber, forms a forced ventilation cooling circuit to control the powder temperature ≤80 degrees Celsius, and finally obtains uniform powder with a median particle size distribution ≤10 micrometers.

[0036] When selecting a Raymond mill: high-manganese steel liners and quartz sand grinding media are used. The material is thrown towards the grinding ring under centrifugal force and is crushed and refined by the grinding rollers. The main grinding machine speed is 1400 to 1800 rpm, the analyzer speed is 800 to 1200 rpm, and the grinding time is 2 to 4 hours. It is equipped with an external cyclone separator and pulse dust collector. The particle size of the finished product is controlled by adjusting the analyzer speed. Unqualified coarse particles are returned to the grinding chamber for re-grinding. During the grinding process, room temperature air is introduced to form an airflow circulation cooling, and the powder temperature is controlled to ≤85 degrees Celsius. Finally, a uniform powder of 100 to 400 mesh is obtained.

[0037] The uniform powder produced after processing by the three types of grinding equipment must meet the requirements of a flowability index ≥60 and no obvious agglomeration to ensure the smooth progress of subsequent granulation and molding processes.

[0038] S3: Dry granulation and molding: A dry composite binder is added to the uniform powder. The binder is a mixture of modified starch powder and nano silica powder, and the amount added is 4% to 8% of the total mass of the powder. The powder is mixed for 10 to 20 minutes at a speed of 60 to 100 revolutions per minute using a high-power mixer to obtain a uniform and plastic powder. The powder is then pressed into spherical particles by a roller granulator and then pressed into green bodies by a hydraulic press or isostatic press.

[0039] Specifically, a dry composite binder is added to the uniform powder. The binder is a mixture of modified starch powder and nano-silica powder, and the amount added is 4% to 8% of the total mass of the powder. The mixture is then mixed for 10 to 20 minutes at a speed of 60 to 100 revolutions per minute using a high-power mixer to obtain a uniform and plastic powder. The powder is then pressed into spherical particles using a roller granulator and then pressed into green bodies using a hydraulic press or an isostatic press.

[0040] When an isostatic press is used for compression molding, the mold for encapsulating the green body is made of elastic polymer material, the pressing medium is water-based emulsion, the density of the green body reaches 55% to 60% of the theoretical density, and the coefficient of variation of density distribution uniformity is less than 5%.

[0041] S4: Stepped temperature sintering: The green body is placed in a high-temperature sintering furnace and sintered using a multi-stage temperature control program. In the first stage, the temperature is raised from room temperature to 600 degrees Celsius at a rate of 5 degrees Celsius per minute and held for 30 minutes. The main purpose of this stage is to completely remove residual bound water, physically adsorbed water, and any trace organic matter (such as residues from dispersants) from the green body, to prevent cracking or blistering of the product due to rapid vaporization of moisture or organic matter in the subsequent high-temperature stages. In the second stage, the temperature is raised to 1200 degrees Celsius at a rate of 3 degrees Celsius per minute and held for 1 hour. In this temperature range, the bauxite matrix begins to undergo preliminary solid-phase reaction, and some low-melting-point impurities form a small amount of liquid phase, promoting preliminary bonding between particles and providing skeletal support for subsequent high-temperature densification. In the third stage, the temperature is raised to 1550 to 1650 degrees Celsius at a rate of 2 degrees Celsius per minute and held for 2 to 4 hours. This stage is the main reaction zone for densification and composite phase formation. At this high temperature, magnesium oxide and aluminum oxide react fully to form a magnesium-aluminum spinel phase, silicon carbide particles form a strong bond with the matrix, and rare earth elements play a grain boundary purifying role. To prevent easily oxidizable components such as silicon carbide from being oxidized at high temperatures, and to suppress the loss of certain volatile components, the entire sintering process is carried out under a protective atmosphere.

[0042] It should be noted that the high-temperature sintering furnace has a full fiber-lined structure and is equipped with a high-precision temperature control system and an atmosphere analyzer. The temperature control accuracy is ±3 degrees Celsius, and the atmosphere analyzer can monitor the oxygen content and gas composition inside the furnace in real time.

[0043] During the third stage of sintering and heat preservation, an intermittent pressure-assisted sintering mechanism is introduced. Axial mechanical pressure of 10 MPa is applied for 5 minutes at 30 minutes, 60 minutes and 90 minutes after the start of heat preservation, respectively, to promote particle rearrangement and eliminate closed pores, so that the relative density of the final sintered body is increased to more than 95%.

[0044] S5: Post-processing and performance control: Forced air cooling or controlled slow cooling is applied to the sintered body, with the cooling rate adjusted to the range of 10 degrees Celsius to 50 degrees Celsius per minute. Subsequently, the cooled composite bauxite products undergo surface finishing and non-destructive testing to ensure that the dimensional tolerance is within ±0.1 mm and that there are no macroscopic defects inside.

[0045] It should be noted that the forced air cooling adopts a multi-segment controllable wind speed cooling device. This device is divided into multiple independent air zones along the length of the product. The wind speed and temperature of each air zone can be adjusted independently. The cooling wind temperature starts from 200 degrees Celsius to avoid sudden cooling. The wind speed is distributed in a gradient along the length of the product, with the highest wind speed zone having a wind speed of 8 meters per second and the lowest wind speed zone having a wind speed of 2 meters per second. This gradient wind speed design is designed to match the heat dissipation needs of different parts of the product, ensuring that the internal thermal stress is released evenly and preventing cracking.

[0046] Non-destructive testing employs a dual inspection system combining ultrasonic flaw detection and real-time X-ray imaging. The ultrasonic frequency is 5 MHz, capable of detecting internal defects with a depth of up to 100 mm and a size greater than 0.5 mm. The X-ray tube voltage is 160 kV, the current is 5 mA, and the imaging resolution reaches 50 micrometers, ensuring that the internal quality of the product meets high standards.

[0047] After cooling, the composite bauxite products undergo surface finishing processes such as grinding or polishing to ensure dimensional tolerances are controlled within ±0.1 mm. Subsequently, rigorous non-destructive testing is performed. This testing employs a dual-mode approach: ultrasonic testing and a real-time X-ray imaging system. Ultrasonic testing uses a 5 MHz longitudinal wave probe, capable of detecting internal defects up to 100 mm deep and larger than 0.5 mm, such as cracks, pores, or inclusions. The real-time X-ray imaging system uses a 160 kV tube voltage and 5 mA current X-ray source, coupled with a high-resolution flat panel detector, achieving an imaging resolution of 50 micrometers, clearly revealing the microscopic structural features and potential defects within the product. Only products confirmed to be free of macroscopic internal defects through this dual testing are allowed into the warehouse.

[0048] It also includes establishing a material performance database using S5-certified products. The database records the chemical composition, process parameters and final performance indicators of each product. Based on this database, a multivariate regression analysis model is used to optimize the batching scheme and sintering process for subsequent production, so that the product performance prediction accuracy is greater than 90%.

[0049] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing composite bauxite, characterized in that: Includes the following steps: S1: Raw material pretreatment and batching: Select bauxite ore for crushing and screening, control the particle size distribution range to 0.1 mm to 5 mm, and accurately measure the functional additive components according to the target composite performance requirements, including magnesium oxide, silicon carbide and rare earth oxides, with the mass percentage error of each component controlled within ±0.5%. S2: Dry co-grinding and homogenization: Based on the particle size requirements of production, select one of ball mill, vertical mill or Raymond mill as the grinding equipment, put the pretreated bauxite and functional additives into the selected grinding equipment, and use appropriate grinding media and grinding methods to achieve material refinement and mixing to ensure that the preset particle size standard is met. S3: Dry granulation and molding: A dry composite binder is added to the uniform powder. The binder is a mixture of modified starch powder and nano-silica powder, and the addition amount is 4% to 8% of the total powder mass. The powder is mixed for 10 to 20 minutes at a speed of 60 to 100 rpm using a high-power mixer to obtain a uniform and plastic powder. The powder is then pressed into spherical granules by a roller granulator, and then pressed into green bodies by a hydraulic press or isostatic press at a pressure of 50 MPa to 100 MPa and a holding time of 30 to 60 seconds. S4: Stepped Temperature Sintering: The green blanks are placed in a high-temperature sintering furnace and sintered using a multi-stage temperature control program. The first stage raises the temperature from room temperature to 600 degrees Celsius at a rate of 5 degrees Celsius per minute and holds for 30 minutes. The second stage raises the temperature to 1200 degrees Celsius at a rate of 3 degrees Celsius per minute and holds for 1 hour. The third stage raises the temperature to 1550 to 1650 degrees Celsius at a rate of 2 degrees Celsius per minute and holds for 2 to 4 hours. The sintering atmosphere is a mixture of nitrogen and argon, with nitrogen comprising 70% to 90% of the gas. The furnace is maintained at a slightly positive pressure of 100 to 500 Pa above atmospheric pressure. S5: Post-processing and performance control: Forced air cooling or controlled slow cooling is applied to the sintered body, with the cooling rate adjusted to the range of 10 degrees Celsius to 50 degrees Celsius per minute. Subsequently, the cooled composite bauxite products undergo surface finishing and non-destructive testing to ensure that the dimensional tolerance is within ±0.1 mm and that there are no macroscopic defects inside.

2. The method for producing composite bauxite according to claim 1, characterized in that: The bauxite ore in S1 is of medium to low grade, with an alumina content of 45% to 65%, an iron oxide content of less than or equal to 5%, and a silicon oxide content of 10% to 25%. After crushing and screening, a strong magnetic separator is used to remove magnetic impurities. The magnetic field strength is 1.0 Tesla to 1.5 Tesla, which reduces the residual iron oxide content in the non-magnetic product to below 2%.

3. The method for producing composite bauxite according to claim 1, characterized in that: The dosage of the functional additives in S1 is based on the ratio of the chemical composition of the bauxite matrix to the target composite phase composition. The amount of magnesium oxide added is 3% to 8% of the mass of bauxite, the amount of silicon carbide added is 5% to 12% of the mass of bauxite, and the rare earth oxides are selected from one or a combination of two of cerium oxide or lanthanum oxide, and the amount added is 0.5% to 2% of the mass of bauxite.

4. The method for producing composite bauxite according to claim 1, characterized in that: In the S3 dry composite binder, the mass ratio of modified starch powder to nano silica powder is 3:1 to 5:1, and both are pulverized by airflow to a particle size ≤5 micrometers; the roller surface of the roller granulator has a semi-circular groove, the roller spacing is adjustable from 0.5 mm to 2 mm, the spherical particle size is 2 mm to 5 mm, and the angle of repose is ≤30 degrees.

5. A method for producing composite bauxite according to claim 1, characterized in that: When an isostatic press is used for pressing in S3, the mold for encapsulating the green blank is made of elastic polymer material, the pressing medium is water-based emulsion, the density of the green blank reaches 55% to 60% of the theoretical density, and the coefficient of variation of density distribution uniformity is less than 5%.

6. A method for producing composite bauxite according to claim 1, characterized in that: The S4 high-temperature sintering furnace has a full fiber lining structure and is equipped with a high-precision temperature control system and an atmosphere analyzer. The temperature control accuracy is ±3 degrees Celsius, and the atmosphere analyzer can monitor the oxygen content and gas composition inside the furnace in real time.

7. A method for producing composite bauxite according to claim 1, characterized in that: In S4, during the third stage of sintering and heat preservation, an intermittent pressure-assisted sintering mechanism is introduced, applying axial mechanical pressure of 10 MPa for a duration of 5 minutes at the 30th, 60th, and 90th minutes after the start of heat preservation.

8. A method for producing composite bauxite according to claim 1, characterized in that: The forced air cooling in S5 employs a multi-segment controllable wind speed cooling device. The cooling air temperature starts at 200 degrees Celsius, and the wind speed is gradually distributed along the length of the product, with the highest wind speed zone at 8 meters per second and the lowest wind speed zone at 2 meters per second, ensuring uniform release of internal thermal stress and preventing cracking. Non-destructive testing utilizes a dual inspection system of ultrasonic flaw detection and real-time X-ray imaging. The ultrasonic frequency is 5 MHz, and the X-ray tube voltage is 160 kV with a current of 5 mA.

9. A method for producing composite bauxite according to any one of claims 1 to 8, characterized in that: It also includes establishing a product performance database, and using a multiple regression analysis model based on this database to optimize the batching scheme and sintering process for subsequent production, with a product performance prediction accuracy of more than 90%.

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