Preparation method of light mullite microporous homogenized material

Abstract

The present invention relates to a preparation method of lightweight mullite microporous homogenized material; the preparation of lightweight mullite microporous homogenized material is carried out by various processes such as ball milling - pressure filtration - drying - forming - sintering - crushing; the micropore diameter can reach the nanometer level, and the castable made of lightweight mullite microporous (nanometer-level) homogenized aggregate can be directly in contact with the flame and can form an "isolation layer" with the slag, slowing down the penetration of molten slag into the interior of the aggregate, so the ability of the material to resist the penetration and erosion of molten slag is improved, and the service life of the lining is greatly extended. It is a new type of high-efficiency energy-saving and emission-reducing material.

Description

Technical Field

[0001] The present invention is used in the field of refractories and belongs to the field of materials technology. Specifically, it relates to a preparation method of poly-light mullite microporous homogenized material. Background Art

[0002] Refractory materials refer to a class of inorganic non-metallic materials with a refractoriness of not less than 1580 °C. Refractoriness is the Celsius temperature at which a refractory cone specimen, without load, resists the action of high temperature without softening and melting down. However, defining it solely by refractoriness can no longer comprehensively describe refractory materials, and 1850 °C is not absolute. It is now defined that materials whose physical and chemical properties allow them to be used in high-temperature environments are called refractory materials. Refractory materials are widely used in industrial fields such as metallurgy, chemical engineering, petroleum, machinery manufacturing, silicate, and power. They are used in the largest amount in the metallurgical industry, accounting for 50% - 60% of the total output. Although existing refractory materials have good fire resistance, they are often relatively heavy, causing difficulties in handling and use during industrial production. Therefore, in the current research on refractory materials, how to achieve the lightweight of refractory materials is one of the main research contents. Currently, the main lightweight refractory materials on the market are aggregates formed by lightweight mullite. Research shows that castables made of lightweight mullite microporous (nanoscale) homogenized aggregates can directly contact the flame and form an "isolation layer" with the slag, slowing down the penetration of molten slag into the interior of the aggregate, thus improving the material's ability to resist the penetration and erosion of molten slag and greatly extending the service life of the lining. It is a new type of high-efficiency energy-saving and emission-reduction material. In the existing technology, the manufacture of lightweight mullite often adopts the process of pressure filtration - drying - forming - sintering - crushing. Moreover, the composition of lightweight mullite itself is not fixed, and it is composed of elements such as coal, iron, aluminum, silicon, and calcium. In the existing technology, aluminosilicate compositions and compositions of alumina and silica are mostly used for the manufacture of lightweight mullite. However, some problems often occur in the manufacture of lightweight mullite aggregates in the existing technology. First, during the manufacture of mullite, no pore-forming agent is added or the composition and addition timing of the added pore-forming agent are incorrect, resulting in uneven pore sizes in the prepared mullite. Eventually, the fire resistance of mullite is insufficient and the size is too large. Traditional pore-forming agents include sawdust, rice husk, starch, etc. However, when these pore-forming agents are added during the preparation of mullite, they often lead to uneven pore sizes, and the pores generated are generally in the millimeter level. Or although relatively small pores can be generated, due to poor viscosity and low strength, cracks often occur in the product, making the prepared mullite not have an advantage compared with traditional thermal insulation materials such as perlite, vermiculite, and ceramsite. In addition, in the selection of raw materials for the manufacture of mullite, the lightweight mullite prepared by traditional aluminosilicate compositions and compositions of alumina and silica cannot meet the fire resistance and size requirements of modern industry. And in the manufacturing process, the traditional method for preparing aggregates is to directly fire, crush, and screen the required raw materials, and obtain large-sized clinkers through crushing and grading. The aggregates prepared by this method have irregular shapes, and it is difficult to control the particle size distribution within each particle size range.Meanwhile, the clinker after forming a specific crystal structure is crushed by various equipment, which affects the shape and performance of its aggregate; the temperature parameters, friction parameters, crushing methods, and forming methods in various technological processes such as ball milling - pressure filtration - drying - forming - sintering - crushing are not adjusted and changed according to the properties of the raw materials, pore formers, and the refractory materials prepared; resulting in poor performance of the prepared mullite. Summary of the Invention

[0003] Technical Problems to be Solved

[0004] Based on the problems mentioned above, the present invention uses aluminum ore to be classified and crushed as the raw material for manufacturing lightweight mullite; uses a new pore former material such as silica as one of the main components of the pore former to prepare the pore former; adjusts and adapts various parameters in real time at each technological stage in the preparation process of lightweight mullite; thereby enhancing the refractory performance of the lightweight mullite aggregate and reducing its size.

[0005] Technical Solution

[0006] A preparation device for a lightweight mullite microporous homogenized material, which includes an aluminum ore detection and classification device, a crushing and screening device, a ball mill, a slurry pond, a filter press, a dryer, a forming machine, a sintering device, a crusher, a classifier, a iron removal device, and a packaging machine.

[0007] Further, the aluminum ore detection and classification device includes a conveying device, a detection device, an ore storage bin, and an alternative storage bin; the conveying device includes conveying roller I and conveying roller II; a conveyor belt is wound around conveying roller I and conveying roller II; a detection platform is arranged above the conveying device, and an ore feeding device is arranged on the detection platform; the driving shaft of conveying roller I is connected to a motor I that can rotate forward and backward; motor I is electrically connected to a control device; an ore storage bin is arranged on one side of the conveyor belt; an alternative storage bin is arranged on the other side of the conveyor belt; both ends of the conveyor belt are respectively abutted against the inlet ends of the ore storage bin and the alternative storage bin.

[0008] Further, the crushing and screening device includes a hopper, a plurality of screening and crushing rollers, a time detection device, a control device, and crushing teeth; a plurality of screening and crushing rollers are arranged side by side; a gap is left between two screening and crushing rollers; the size of the gap is not greater than 3 mm; the crushing teeth are evenly arranged on the crushing rollers; each crushing roller is respectively connected to a corresponding motor II through a driving shaft; motor II is electrically connected to the control device.

[0009] Further, the ball mill includes a support platform; an arc-shaped rotating groove is provided on the upper part of the support platform; an annular ball mill is provided inside the arc-shaped rotating groove; a number of steel balls are provided inside the annular ball mill; the drive shaft of the annular ball mill is connected to the ball mill motor; the annular ball mill is driven to rotate by the ball mill motor; a water storage tank is provided on one side of the annular ball mill, a water outlet pipe is connected to the water outlet of the water storage tank, and a water outlet valve is provided on the water outlet pipe; the other end of the water outlet pipe communicates with the inside of the annular ball mill, and both the ball mill motor and the water outlet valve are electrically connected to the control device.

[0010] Further, the filter press includes a number of filter plates and a pressing plate; the number of filter plates are sequentially arranged on the moving track, and a filter chamber is formed between the number of filter plates; a pushing device is provided on one side of the pressing plate, and a plurality of feeding holes are provided on the side surfaces of the filter plates; a water spraying device is provided at the upper end of the filter plates, the water spraying device includes a water spraying pipe and a number of water spray heads, and each water spray head corresponds to the filter chamber at the lower end; a number of water drainage holes are provided on the moving track; a water storage tank is provided at the lower end of the water drainage holes; the pushing device of the filter plates is electrically connected to the control device.

[0011] Further, the dryer includes a drying box, and the inside of the drying box is divided into an upper layer of the drying box and a lower layer of the drying box; a hot air device is provided inside the upper layer of the drying box; a sliding plate I and a sliding plate II are provided on the upper layer of the drying box, the inclination angle of the sliding plate I is 30 degrees, and the inclination angle of the sliding plate II is 20 degrees; a number of water drainage holes are provided on both the sliding plate I and the sliding plate II; a discharge port is provided on the sliding plate II; the lower end of the sliding plate II is provided with the lower layer of the drying box; electric heating tubes are provided inside the lower layer of the drying box; a reverse conveying device is provided on the outer side wall of the upper layer of the drying box; the reverse conveying device includes a conveying box and a detection device; one side wall of the conveying box is one side wall of the drying box; a vertical conveying device is provided inside the conveying box, a sliding plate is provided at the upper part of the conveying box, and the other end of the sliding plate is connected to the sliding plate I.

[0012] Further, the molding machine includes a mold table and a molding table; the mold table is arranged below the molding table; a mold track and a molding groove are provided on the mold table; a number of molding grooves are provided, and a transverse track I and a transverse track II are respectively provided on both sides of the molding groove; both sides of the transverse track I and the transverse track II are arranged inside the mold track and can slide on the mold track; the molding table is connected to a downward pressing device, and a pressing block is provided at the lower part of the molding table.

[0013] Further, a temperature control device and a temperature detection device are provided inside the sintering device; the temperature control device controls the temperature inside the sintering device.

[0014] Further, the classifier includes a primary classifier and a secondary classifier.

[0015] A preparation method of lightweight mullite microporous homogenized material, including a manufacturing method of pore-forming agent particles containing silicon dioxide; preparing monodisperse microporous silicon dioxide particles by sol-gel method; and pulverizing part of the silicon dioxide particles to obtain silicon dioxide powder; adding ammonium bicarbonate, polymethacrylate and silicon dioxide particles into distilled water, and oscillating it with ultrasonic wave, and performing freeze layering suspension after oscillation; centrifuging the layered suspension by a centrifuge device to precipitate the particles in the mixed solution; filtering the precipitated particles and separating them out, and drying to obtain granular microspheres; uniformly coating the surface of the obtained granular microspheres with sufficient silicon dioxide powder, and freezing and drying the granular microspheres coated with silicon dioxide powder at a temperature of 3-8 degrees, and then performing high-temperature sintering to obtain pore-forming agent particles containing silicon dioxide with a size in the nanometer level.

[0016] Further, the preparation method of the lightweight mullite microporous homogenized material further includes the following steps: putting the pore-forming agent manufactured by the above-mentioned manufacturing method of pore-forming agent particles containing silicon dioxide into a pore-forming agent storage box for standby; detecting and classifying the collected bauxite; putting the bauxite on a detection platform, and the detection device on the detection platform detects the mass content of aluminum in the bauxite, and the bauxite with an aluminum mass content of more than 60% is considered qualified bauxite; the bauxite with an aluminum mass content of 50%-60% is considered standby bauxite; the bauxite with an aluminum mass content of less than 40% is considered unqualified bauxite. If the detected aluminum mass content is more than 60%, the bauxite is sent to the conveyor belt through the ore feeding device, and the rotation direction of motor I is controlled by the control device so that the bauxite is sent into the ore warehouse; if the detected aluminum mass content in the bauxite is between 50%-60%; the rotation direction of motor I is controlled by the control device so that the bauxite is sent to the alternative warehouse; if the detected aluminum mass content is less than 40%, it is directly put into the waste collection device for other uses.

[0017] Further, after the amount of bauxite in the ore bin reaches a certain quantity, stop the detection and grading of bauxite in the first step; put the qualified bauxite in the ore bin into the hopper. Initially, set the amount of bauxite put into the hopper as a fixed value Ε, and set the speed of putting bauxite into the hopper as a constant value ν / min. Then the time for the qualified bauxite to be injected into the hopper is T = Ε / ν. Start motor II after the bauxite begins to be put into the hopper, and use the time detection device to detect the duration of starting the motor. Set the initial speed of the motor as Α0, the initial starting time of the motor as t0, and set the detected duration of motor II as t1. Set the conversion time point of motor II as t2, and any detected t1 value from the start of motor II is less than t2. Define the real-time speed reached by motor II during rotation as A1. Control the real-time speed of motor II through the control device: A1 = Α0 + K(t1 - t0), where K is the speed increase coefficient. When the time detection device detects that t0 < t1 < t2, the control device controls the rotation direction of motor II corresponding to each screening and crushing roller to make each screening and crushing roller rotate forward and backward within a range of 30 degrees of rotation, so that each screening and crushing roller continuously rotates 30 degrees in the counterclockwise and clockwise directions. When the time detection device detects that the time reaches t2, the control device controls the speed and rotation direction of motor II to be constant at this time, and controls the rotation directions of the corresponding motors II of two adjacent screening and crushing rollers to be opposite, so that two adjacent screening and crushing rollers rotate towards each other at the same constant speed.

[0018] Further, grading is carried out according to different mullite models, and the mixing ratio is 80 - 95% by weight

[0019] Further, put the granular bauxite passed through the screening and crushing rollers into the ball mill and add water for wet ball milling; set the standard rotation speed of the ball mill motor as P0, set the minimum rotation speed of the ball mill motor as Pmin, take the maximum rotation speed of the ball mill motor as Pmax, and the initial rotation speed Pt of the ball mill motor satisfies Pmin < Pt < Pmax. Here, Pmin is set such that when the ball mill rotates, the upward rotation height of the steel balls following the ball mill is too small to effectively friction the bauxite; Pmax is set such that when the ball mill rotates, the steel balls closely follow the wall of the ball mill and cannot effectively friction the bauxite. Set the initial amount of bauxite added to the ball mill as E, and set the real-time amount of bauxite added as Et. During the process of adding bauxite, the change value of the motor speed of the ball mill is P = P0×(Et - E) / ε, where ε is the coefficient of the motor speed change value; and P < Pmax. After all the bauxite is added, control the rotation speed of the motor at this time to be a constant speed; and at the same time, add the pore-forming agent particles containing silicon dioxide manufactured by the above-mentioned manufacturing method of the pore-forming agent particles of silicon dioxide and continue wet ball milling. After continuing wet ball milling for 0.5 h, the ball milling process is completed.

[0020] Further, the ball-milled aluminum ore particles are placed on a screening device for screening, and the aluminum ore particles passing through the screening device enter a filter press to be mixed with the slurry in the slurry pond for standby.

[0021] Further, start the pushing device of the pressing plate to push the filter plates to move relatively closer to form a filter chamber; initially, pre-compress each filter plate, detect the moving distance L0 of the pushing pressing plate on the slide rail during pre-compression, and inject the mixed liquid of aluminum ore particles mixed with the slurry into the filter chamber through the feed holes on the filter plates after pre-compression for pre-compression and water drainage to form a shape; and detect the pre-compressed and formed model; when it is detected that the size of the pre-compressed and formed model is within 5% of the standard model size, start the pressing plate to move L0 on the slide rail for formal pressing; when it is detected that the size of the pre-compressed and formed model is less than the standard model size by more than 5%, the moving distance of the pressing plate on the slide rail during formal pressing is less than L0 to prevent excessive pressure between the filter plates from damaging the filter plates; when it is detected that the size of the pre-compressed and formed model is greater than the standard model size by more than 5%, the moving distance of the pressing plate on the slide rail during formal pressing is greater than L0 to increase the pressure between the two filter plates. After filtration, open each filter plate to make the filtered mud cake fall out and turn on the sprinkler head to spray water to clean the filtered slurry, and the cleaned water is discharged through the water drainage holes on the moving track.

[0022] Further, put the preliminarily dehydrated mud cake after filtration into a dryer for drying; the mud cake first enters the upper layer of the drying box; it slides down on the lower slide plate Ⅰ in the upper layer of the drying box and enters the lower slide plate Ⅱ; the remaining water on the mud cake is discharged through the water drainage holes on the lower slide plate Ⅰ and the lower slide plate Ⅱ, and turn on the hot air device to conduct preliminary drying on the mud cake; detect the moisture content of the mud cake during the process of passing through the lower slide plate Ⅱ. When it is detected that the moisture content is higher than the standard value ξ, the mud cake after passing through the lower slide plate Ⅱ enters the reverse conveying device and enters the upper layer of the drying box again for primary drying; when it is detected that the moisture content is lower than the standard value ξ; open the discharge port on the lower slide plate Ⅱ to make the mud cake enter the lower layer of the drying box for secondary drying.

[0023] Further, send the dried materials that meet the requirements into a brick press for forming. The minimum forming pressure is 1300 tons. During forming, first put the mud cake into the forming groove on the mold table. After the mud cake is placed in each forming groove, move the forming groove on the mold track and move it to the lower part of the forming table, and press it down through the pressing device to make the mud cake form in the forming groove.

[0024] Further, the formed green bricks are fired in a tunnel kiln. The initial firing temperature is set at 1400 °C, the initial firing time is set at M0, and the final end time is set at Mt. The time between the heating time M0 and Mt is evenly divided into M 0+1 、M 0+2 、M 0+3 .......M 0+N .......Mt; when the initial firing time is M0, the firing temperature is 1400 °C. During the time period between M0 and M 0+1 , the temperature is 1400 °C. When the heating time reaches M0 + 1, the temperature change is controlled to 1400 °C + Φ, where Φ is the temperature increase coefficient. When the time is within the time period between M 0+1 and M 0+2 , the heating temperature is 1400 °C + Φ. When the heating time reaches M 0+2 , the heating temperature is 1400 °C + Φ + Φ 2 . By analogy, when the heating time reaches Mt, the heating temperature is 1400 °C + Φ + Φ 2 ........+ Φ t ; the heating temperature within each interval time period is constant, and the highest heating temperature does not exceed 1600 °C. When the heating time reaches Mt, the temperature is maintained until the firing is completed.

[0025] Further, after cooling after firing, the green bricks are put into a jaw crusher for crushing, and the crushing process is completed after 20 minutes of crushing.

[0026] Further, the crushed materials are screened and their composition is detected; classification is carried out according to the detection results of various parameters such as bulk density (g / cm3), compressive strength (Mpa), apparent porosity (%), and water absorption (%); the aggregates with bulk density ≤ 1.50, compressive strength ≥ 70, apparent porosity ≥ 43.0, and water absorption ≤ 29.0 are stored in alternative warehouse I; the bulk density

[0027] ≤ 1.80, compressive strength ≥ 90, apparent porosity ≥ 38.0, and water absorption ≤ 22.0 of the aggregates are put into alternative warehouse II; the aggregates with bulk density ≤ 2.0, compressive strength ≥ 110, apparent porosity ≥ 28.0, and water absorption ≤ 17.0 are put into alternative warehouse III.

[0028] Further, the aggregates in each alternative warehouse are subjected to iron removal treatment to remove the mechanical iron added during the crushing process.

[0029] Further, the materials from which the mechanical iron has been removed are packaged and the finished products are warehoused.

[0030] The performance indicators of the poly-light mullite microporous homogenized material produced by the above steps are as follows:

[0031]

[0032] Beneficial effects

[0033] (1) Based on the manufacturing process of traditional lightweight mullite aggregate, a pore-forming agent mainly made of silicon dioxide is added, enabling the micropore diameter of the lightweight mullite aggregate to reach the nanometer level.

[0034] (2) Using the complete preparation process of ball milling - pressure filtration - drying - forming - sintering - crushing, the pores of the prepared lightweight mullite aggregate can reach the nanometer level, with uniform pore size, lower thermal conductivity, and better heat insulation performance.

[0035] (3) Based on the traditional preparation of lightweight mullite aggregate, specific limitations are imposed on the crushing time, rotational speed of the crushing device, rotational speed of the ball milling device, wet ball milling time, specific drying method, specific pressure in the pressure filtration chamber during pressure filtration, specific pressure during forming, and specific temperature change process during sintering in each process step; through the optimization and improvement of process parameters, the composition of the prepared lightweight mullite aggregate is stable, the volume is stable, the strength is high, the structural airtightness is good, and the weight of the castable made of this lightweight mullite micropore homogenized aggregate can be reduced by 30 - 50%; the staged increase and staged maintenance of temperature during the firing process result in a smaller density and lower apparent porosity of the aggregate compared to the traditional sintering process with a constant temperature or a steadily rising temperature. Brief description of the drawings

[0036] Figure 1 is the detection and grading device;

[0037] Figure 2 is the schematic diagram of the crushing and screening device;

[0038] Figure 3 is the schematic diagram of the ball mill;

[0039] Figure 4 is the schematic diagram of the filter press;

[0040] Figure 5 is the schematic diagram of the drying device;

[0041] Figure 6 is the schematic diagram of the molding machine.

[0042] 1 - conveyor belt; 2 - alternative warehouse; 3 - ore warehouse; 4 - hopper; 5 - screening and crushing roller; 6 - crushing teeth; 7 - support platform; 8 - ball mill; 9 - water storage tank; 10 - pressing plate; 11 - filter plate; 12 - water spray pipe; 13 - sliding plate Ⅰ; 14 - sliding plate Ⅱ; 15 - reverse conveying device; 16 - mold table; 17 - molding table. Detailed implementation manners

[0043] A preparation device for lightweight mullite microporous homogenized material, which includes an aluminum ore detection and classification device, a crushing and screening device, a ball mill, a slurry pond, a filter press, a dryer, a molding machine, a sintering device, a crusher, a classifier, a iron removal device, and a packaging machine. The aluminum ore detection and classification device includes a conveying device, a detection device, an ore storage and an alternative storage; the conveying device includes conveying rollers Ⅰ and Ⅱ; a conveyor belt 1 is wound around the conveying rollers Ⅰ and Ⅱ; a detection platform is arranged above the conveying device, and an ore pushing device is arranged on the detection platform; the driving shaft of the conveying roller Ⅰ is connected to a motor Ⅰ that can rotate forward and backward; the motor Ⅰ is electrically connected to a control device; an ore storage 3 is arranged on one side of the conveyor belt; an alternative storage 2 is arranged on the other side of the conveyor belt; the two ends of the conveyor belt are respectively abutted against the inlet ends of the ore storage and the alternative storage. The crushing and screening device includes a hopper 4, several screening and crushing rollers 5, a time detection device, a control device, and crushing teeth 6; several screening and crushing rollers 5 are arranged side by side; there is a gap between two screening and crushing rollers 5; the size of the gap is not greater than 3 mm; the crushing teeth 6 are evenly arranged on the crushing rollers 5; each crushing roller 5 is respectively connected to a corresponding motor Ⅱ through a driving shaft; the motor Ⅱ is electrically connected to the control device. The ball mill 8 includes a support platform; an arc-shaped rotating groove is arranged on the upper part of the support platform; a ring-shaped ball mill is arranged inside the arc-shaped rotating groove; several steel balls are arranged inside the ring-shaped ball mill 8; the driving shaft of the ring-shaped ball mill is connected to a ball mill motor; the ring-shaped ball mill 8 is driven to rotate by the ball mill motor; a water storage tank 9 is arranged on one side of the ring-shaped ball mill, the water outlet of the water storage tank 9 is connected to a water outlet pipe, and a water outlet valve is arranged on the water outlet pipe; the other end of the water outlet pipe communicates with the inside of the ring-shaped ball mill, and both the ball mill motor and the water outlet valve are electrically connected to the control device. The filter press includes several filter plates 11 and a pressing plate 10; several filter plates 11 are sequentially arranged on a moving track, and a filter chamber is formed between several filter plates 11; a pushing device is arranged on one side of the pressing plate 10, and a plurality of feeding holes are arranged on the side surface of the filter plate; a water spraying device is arranged at the upper end of the filter plate, and the water spraying device includes a water spraying pipe 12 and several water spray heads, and each water spray head corresponds to the filter chamber at the lower end; a plurality of water drainage holes are arranged on the moving track; a water storage tank is arranged at the lower end of the water drainage holes; the pushing device of the filter plate is electrically connected to the control device. The dryer includes a drying box, and the inside of the drying box is respectively the upper layer and the lower layer of the drying box; a hot air device is arranged inside the upper layer of the drying box; a sliding plate Ⅰ 13 and a sliding plate Ⅱ 14 are arranged in the upper layer of the drying box, the inclination angle of the sliding plate Ⅰ 13 is 30 degrees, and the inclination angle of the sliding plate Ⅱ 14 is 20 degrees; water drainage holes are arranged on both the sliding plate Ⅰ 13 and the sliding plate Ⅱ 14; a discharge port is arranged on the sliding plate Ⅱ 14; the lower end of the sliding plate Ⅱ 14 is the lower layer of the drying box; electric heating tubes are arranged inside the lower layer of the drying box; a reverse conveying device 15 is arranged on the outer side wall of the upper layer of the drying box; the reverse conveying device 15 includes a conveying box and a detection device; one side wall of the conveying box is the side wall of the drying box;A vertical conveying device is arranged inside the conveying box, and a sliding plate is arranged at the upper part of the conveying box. The other end of the sliding plate is connected to the lower sliding plate I 13. The molding machine includes a mold table 16 and a molding table 17; the mold table 16 is arranged below the molding table 17; a mold track and a molding groove are arranged on the mold table 16; there are multiple molding grooves, and a transverse track I and a transverse track II are respectively arranged on both sides of the molding groove; both sides of the transverse track I and the transverse track II are arranged in the mold track and can slide on the mold track; the molding table is connected to a downward pressing device, and a pressing block is arranged at the lower part of the molding table; a temperature control device and a temperature detection device are arranged inside the sintering device; the temperature control device controls the temperature inside the sintering device. The classifier includes a primary classifier and a secondary classifier.

Claims

1. A method for preparing a mullite microporous homogenized material, characterized in that: The following steps are involved: Step 1, preparing a pore-forming agent; Step 2, selection of raw materials: select aluminum ore according to the different mullite contents, and stack them in grades after testing; Step 3: Crushing of raw materials: The graded aluminum ores are crushed separately, and the particle size after crushing is no more than 3mm; Step 4, ingredients: grade according to the different mullite contents, with the proportion being 80%-95% by weight; Step 5, wet ball milling: the graded mixture enters the ball mill, and pore-forming agent is added at 5%-20% by weight for ball milling, and the slurry fineness is not less than 400 mesh; Step 6: The slurry that reaches the required fineness is placed in a mud pool for standby use; Step 7, filter pressing: filter the slurry in the mud pool with a filter press, and the water content after filtration is no more than 23%; Step 8, drying: the mud cake after filtration is put into the drying equipment for drying, and the moisture content after drying is required to be no higher than 15%; Step 9, molding: the dried materials that meet the requirements are sent to the brick press for molding, and the minimum molding pressure is 1300 tons; Step 10, firing: the formed bricks are placed in a tunnel kiln for firing at a temperature not less than 1400°C; Step 11, crushing: crush the fired bricks with a jaw crusher; Step 12: Classification: The crushed materials are screened and tested for composition, and then classified according to the test results; Step 13, iron removal: the classified materials are subjected to iron removal treatment to remove the mechanical iron added during the crushing process; Step 14: Packaging: Remove the materials from the mechanical iron and pack them for storage; Among them, in step 1, the pore-forming agent is prepared by a sol-gel method to prepare monodisperse microporous silica particles; and a part of the silica particles are crushed to obtain silica powder; ammonium bicarbonate, polymethacrylate and silica particles are added to distilled water, and they are shaken by ultrasound, and then frozen and layered and suspended after shaking; the layered suspension is centrifuged by a centrifugal device to allow the particles to precipitate in the mixed liquid; the precipitated particles are filtered and separated, and then dried to obtain particle microspheres; the surface of the obtained particle microspheres is uniformly coated with a sufficient amount of silica powder, and the particle microspheres coated with silica powder are frozen and dried at a temperature of 3-8 degrees, and then sintered at high temperature to obtain nanometer-sized silica-containing pore-forming agent particles; In step 2, the aluminum ore detection and grading device includes a conveying device, a detection device, an ore storage and an alternative storage; the conveying device includes a conveying roller I and a conveying roller II; The conveyor belt is wound around conveyor rollers Ⅰ and Ⅱ; a detection platform is arranged above the conveyor device, and an ore feeding device is arranged on the detection platform; the driving shaft of conveyor roller Ⅰ is connected to a forward and reverse motor Ⅰ; motor Ⅰ is electrically connected to a control device; an ore storage is arranged on one side of the conveyor belt; an alternative storage is arranged on the other side of the conveyor belt; both ends of the conveyor belt are respectively against the entrance ends of the ore storage and the alternative storage; In step 3, the crushing and screening device includes a hopper, a plurality of screening and crushing rollers, a time detection device, a control device and crushing teeth; the plurality of screening and crushing rollers are arranged side by side; a gap is left between two screening and crushing rollers; the size of the gap is not greater than 3 mm; the crushing teeth are evenly arranged on the crushing rollers; each crushing roller is connected to a corresponding motor II through a drive shaft; the motor II is electrically connected to the control device; In step 5, the wet ball mill controls the speed of the ball mill motor, and the speed change value of the ball mill motor is related to the real-time amount Et of the added aluminum ore; In step 10, the firing temperature increases from 1400° C., the heating temperature in each interval time period is constant, and the highest heating temperature is no higher than 1600° C. When the heating time reaches a fixed value, the temperature is maintained until the firing is completed.

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