Search

CN-122010539-A - Method for producing composite bauxite

CN122010539ACN 122010539 ACN122010539 ACN 122010539ACN-122010539-A

Abstract

The application relates to a method for producing composite bauxite, which comprises the steps of S1, raw material pretreatment and batching, S2, dry co-grinding and homogenization, S3, dry granulation and molding, S4, step-type heating sintering, S5, post-treatment and performance regulation, wherein the method for producing composite bauxite realizes the highly uniform combination and strong interface combination of bauxite and various functional additives on a microscopic scale through a series of synergistic optimization steps of accurate raw material pretreatment and batching, wet co-grinding homogenization, spray granulation molding, step-type heating sintering and post-treatment performance regulation, and effectively solves the problems of uneven component dispersion, multiple interface defects and functional component volatilization or structural degradation caused by a high-temperature process in the prior art.

Inventors

  • CHEN LI

Assignees

  • 贵州蒙福新材料有限公司

Dates

Publication Date
20260512
Application Date
20260205

Claims (9)

  1. 1. A method for producing composite bauxite is characterized by comprising the following steps: S1, raw material pretreatment and batching, namely selecting bauxite raw ore for crushing and screening, controlling the grain size distribution range to be 0.1-5 mm, and accurately metering functional additive components comprising magnesium oxide, silicon carbide and rare earth oxide according to the target composite performance requirement, wherein the mass percentage error of each component is controlled within +/-0.5%; S2, dry co-grinding and homogenizing, namely selecting one of a ball mill, a vertical mill or a Raymond mill as grinding equipment according to the granularity requirement required by production, putting pretreated bauxite and a functional additive into the selected grinding equipment, and adopting an adaptive grinding medium and a grinding mode to refine and mix materials so as to ensure that the preset granularity standard is reached; S3, dry granulation and molding, namely adding a dry composite bonding agent which is a compound of modified starch powder and nano silicon dioxide powder into the uniform powder, wherein the addition amount is 4-8% of the total mass of the powder, mixing for 10-20 minutes by adopting a powerful mixing mill at a rotating speed of 60-100 revolutions per minute to obtain uniform plastic powder, pressing the uniform plastic powder into spherical particles by a pair-roller granulator, and pressing the spherical particles into a green body by a hydraulic press or an isostatic press, wherein the pressing pressure is 50-100 MPa, and the pressure maintaining time is 30-60 seconds; S4, step-heating sintering, namely placing the green body into a high-temperature sintering furnace, and sintering by adopting a multi-stage temperature control program, wherein the temperature of the green body is raised to 600 ℃ from room temperature at the rate of 5 ℃ per minute and kept for 30 minutes in the first stage, the temperature of the green body is raised to 1200 ℃ at the rate of 3 ℃ per minute and kept for 1 hour in the second stage, the temperature of the green body is raised to 1550 ℃ to 1650 ℃ at the rate of 2 ℃ per minute and kept for 2 hours to 4 hours in the third stage, the sintering atmosphere is a mixed gas of nitrogen and argon, the volume fraction of the nitrogen is 70 to 90 percent, and the micro-positive pressure state higher than the atmospheric pressure of 100 Pa to 500 Pa is maintained in the furnace And S5, carrying out forced air cooling or controlled slow cooling on the sintered body, regulating the cooling rate to be within a range of 10-50 ℃ per minute, and then carrying out surface finishing and nondestructive testing on the cooled composite bauxite product to ensure that the dimensional tolerance is within +/-0.1 mm and no macroscopic defect exists in the interior.
  2. 2. The method for producing composite bauxite according to claim 1, wherein the bauxite raw ore in S1 is medium-low grade bauxite, the mass content of alumina is 45% to 65%, the mass content of ferric oxide is less than or equal to 5%, the mass content of silicon oxide is 10% to 25%, a high-intensity magnetic separator is used for removing magnetic impurities after crushing and screening, the magnetic field strength is 1.0 tesla to 1.5 tesla, and the residual quantity of ferric oxide in a non-magnetic product is reduced to below 2%.
  3. 3. The method of producing composite bauxite according to claim 1 wherein the functional additive in S1 is metered based on the bauxite base chemical component and the target composite phase composition, the magnesium oxide is added in an amount of 3 to 8% by mass of bauxite, the silicon carbide is added in an amount of 5 to 12% by mass of bauxite, and the rare earth oxide is selected from one or two of cerium oxide and lanthanum oxide, and the added amount is 0.5 to 2% by mass of bauxite.
  4. 4. The method for producing composite bauxite in accordance with claim 1, wherein the mass ratio of modified starch powder to nano silicon dioxide powder in the S3 dry composite binder is 3:1 to 5:1, and the modified starch powder and the nano silicon dioxide powder are crushed by air flow until the particle size is less than or equal to 5 microns, semicircular grooves are formed on the roller surface of the roller granulator, the adjustable range of the roller spacing is 0.5 mm to 2 mm, the particle size of spherical particles is 2 mm to 5 mm, and the repose angle is less than or equal to 30 degrees.
  5. 5. The method of producing composite bauxite in accordance with claim 1, wherein when said S3 compacting is performed by an isostatic press, a mold for encapsulating a green body is made of an elastic polymer material, a compacting medium is a water-based emulsion, a green body density reaches 55% to 60% of a theoretical density, and a density distribution uniformity coefficient of variation is less than 5%.
  6. 6. The method of producing composite bauxite according to claim 1, wherein the high temperature sintering furnace in S4 is of a full fiber lining structure, a high precision temperature control system and an atmosphere analyzer are provided, the temperature control precision is + -3 ℃, and the atmosphere analyzer can monitor the oxygen content and the gas composition in the furnace in real time.
  7. 7. A method for producing composite bauxite in accordance with claim 1 wherein during the third stage sintering soak period in S4, an intermittent pressure assisted sintering mechanism is introduced, and axial mechanical pressure of 5 minutes duration and 10 MPa pressure is applied at 30 minutes, 60 minutes and 90 minutes after initiation of soak period.
  8. 8. The method of producing composite bauxite according to claim 1, wherein the forced air cooling in S5 is performed by a multi-section controllable air speed cooling device, the cooling air temperature is started from 200 ℃, the air speed is distributed in a gradient manner along the length direction of the product, the air speed in the highest air speed area is 8 m/S, and the air speed in the lowest air speed area is 2 m/S, so that the thermal stress in the product is ensured to be released uniformly, and cracking is avoided. The nondestructive detection adopts double detection of ultrasonic flaw detection and an X-ray real-time imaging system, the ultrasonic frequency is 5 MHz, the voltage of an X-ray tube is 160 kilovolts, and the current is 5 milliamperes.
  9. 9. The method according to any one of claims 1 to 8, further comprising creating a product performance database, wherein the batch scheme and sintering schedule of the subsequent production are optimized by using a multiple regression analysis model based on the database, and wherein the accuracy of product performance prediction is greater than 90%.

Description

Method for producing composite bauxite Technical Field The application relates to the technical field of bauxite production, in particular to a method for producing composite bauxite. Background With the continuous increase of the demand of modern industry for high-performance inorganic nonmetallic materials, bauxite has become a key basic raw material in the fields of refractory materials, metallurgy, chemical industry, ceramics and the like due to the excellent high temperature resistance, chemical stability and mechanical strength. However, the natural bauxite has single component and limited performance, and is difficult to meet the comprehensive requirements of high-end application scenes on the multifunctional integration of materials, such as high refractoriness, thermal shock resistance and volume stability in a high-temperature furnace lining, and higher standards on purity, particle size distribution and functional recombination are put forward in the catalytic or precise ceramic field. This has prompted industry to move from single minerals to complex functional materials to break through the natural resource performance bottleneck. The development of the composite bauxite focuses on the realization of the cooperative improvement of the material performance by introducing functional components and optimizing the preparation process. The core aim is to construct a novel bauxite system with high stability, strong interface combination and adjustable functional characteristics, so that the application boundary of the bauxite system under severe working conditions is expanded. However, the existing composite modification technology still faces multiple limitations, on one hand, poor compatibility of additives such as magnesium oxide, silicon carbide and the like with bauxite matrixes is easy to cause uneven dispersion and increase of interface defects, and the overall mechanical and thermal properties of the materials are obviously weakened, on the other hand, the mainstream high-temperature sintering or melting composite technology is high in energy consumption and long in period, and is easy to cause volatilization or structural degradation of functional components, so that the controllability and consistency of the composite effect are difficult to ensure. In addition, the current compound formula is mostly dependent on experience trial and error, and lacks a system design based on a component-to-component physical and chemical matching mechanism, so that a performance synergistic effect is difficult to release, and meanwhile, aiming at the utilization of middle-low-grade bauxite, the problems of low purification efficiency, more impurity residues, limited additional value improvement and the like commonly exist in the prior art, so that the resource waste and the cost pressure coexist. The defects cause the difficulty in the aspects of composite uniformity, process economy and resource sustainability of the existing production method, and severely restrict the large-scale application of the high-performance composite bauxite. Thus, a method for producing composite bauxite is needed. Disclosure of Invention The invention aims to provide a method for producing novel composite refractory clay, which aims to solve the technical problems in the background technology. In order to achieve the above purpose, the invention provides a method for producing composite bauxite, which comprises the following steps: S1, raw material pretreatment and batching, namely selecting bauxite raw ore for crushing and screening, controlling the grain size distribution range to be 0.1-5 mm, and accurately metering functional additive components comprising magnesium oxide, silicon carbide and rare earth oxide according to the target composite performance requirement, wherein the mass percentage error of each component is controlled within +/-0.5%; S2, dry co-grinding and homogenizing, namely selecting one of a ball mill, a vertical mill or a Raymond mill as grinding equipment according to the granularity requirement required by production, putting pretreated bauxite and a functional additive into the selected grinding equipment, and adopting an adaptive grinding medium and a grinding mode to refine and mix materials so as to ensure that the preset granularity standard is reached; S3, dry granulation and molding, namely adding a dry composite bonding agent which is a compound of modified starch powder and nano silicon dioxide powder into the uniform powder, wherein the addition amount is 4-8% of the total mass of the powder, mixing for 10-20 minutes by adopting a powerful mixing mill at a rotating speed of 60-100 revolutions per minute to obtain uniform plastic powder, pressing the uniform plastic powder into spherical particles by a pair-roller granulator, and pressing the spherical particles into a green body by a hydraulic press or an isostatic press, wherein the pressing pressure is 50-100 MPa, and the pressure maintaini