A method for preparing silica checker bricks for high-density, low-porosity hot blast stoves

Abstract

This invention discloses a method for preparing silica checker bricks for high-density, low-porosity hot blast stoves, belonging to the field of refractory material preparation technology. The method includes the following steps: raw material selection and pretreatment, optimizing the particle size distribution of silica sand (coarse particles ≤5%, medium particles 70-80%, fine powder 15-20%), and introducing silica brick sand particles and silica fine powder to achieve close packing; batching and mixing, adding mineralizers, fluorite powder, binders, and high-efficiency water-reducing agents in proportion, and mixing until uniform through a specific feeding sequence; semi-dry pressing, using double-sided pressing technology to control the apparent porosity of the brick blank to ≤19.0% and the bulk density to ≥2.10 g / cm³; after drying, using a segmented firing regime, holding at 1420-1450℃ for 18-36 hours to promote the conversion of cristobalite to tridymite, with a residual quartz content ≤1.0%. This invention achieves high density, low porosity, high volume stability, and excellent high-temperature performance of the brick body through particle size optimization, composite additives, and precise firing control.

Description

Technical Field

[0001] This invention relates to the field of refractory material preparation technology, and in particular to a method for preparing silica checker bricks for high-density, low-porosity hot blast stoves. Background Technology

[0002] As the core regenerative heat exchange device in the blast furnace ironmaking system, the performance of the checker bricks in the hot blast stove directly determines its heat storage efficiency, blast temperature, and long-term operational reliability. With the continuous development of blast furnace smelting technology towards higher blast temperatures, higher oxygen enrichment, and larger pulverized coal injection, more stringent requirements are placed on the comprehensive performance of the hot blast stove checker bricks: they not only need extremely high high-temperature structural strength, excellent creep resistance and load softening temperature, but also must possess extremely low thermal expansion coefficients and excellent volumetric stability to ensure the stability of the masonry structure and unobstructed airflow channels under long-term high-temperature, high-pressure cyclic loads.

[0003] Siliceous refractories are widely used in the high-temperature zones of hot blast stoves due to their high SiO2 content, excellent refractoriness, strong resistance to acid erosion, and moderate price. However, traditional silica brick products have the following inherent defects: The contradiction between density and porosity: Siliceous checker bricks prepared by conventional processes typically have high apparent porosity (≥24%) and low bulk density (≤1.80 g / cm³). This results in insufficient structural strength, thermal conductivity, and heat storage capacity of the bricks, affecting the thermal efficiency and service life of the hot blast stove.

[0004] Volumetric instability caused by residual quartz: Incomplete quartz crystal transformation during the firing process of silica bricks can lead to excessively high residual quartz content in the product (typically >1.5%). Residual quartz undergoes a continuous and delayed crystal transformation (e.g., cristobalite → tridymite) at the service temperature of the hot blast stove, accompanied by unpredictable volume expansion. This is the main risk source leading to cracking, deformation, and even collapse of the hot blast stove masonry.

[0005] Insufficient high-temperature creep resistance: Under long-term high temperature and load, traditional silica bricks are prone to creep deformation, which can lead to blockage or misalignment of the checker brick channels, affecting air supply efficiency, and in severe cases, requiring furnace shutdown for maintenance. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of poor product volume stability, insufficient high-temperature creep resistance, and the risk of expansion and cracking in hot blast stoves caused by the low density, high apparent porosity, and excessive residual quartz content of traditional silica bricks in the prior art. Therefore, a method for preparing silica checker bricks for hot blast stoves with high density and low porosity is proposed.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing silica check bricks for a high-density, low-porosity hot blast stove includes the following steps: Step S1, Raw material selection and pretreatment: Silica is washed, crushed, and pulverized to prepare silica sand particles with a particle size range of 0–2.2 mm. The particle size distribution is controlled as follows: coarse particles (>2.0 mm) ≤5.0%, medium particles (2.0–0.088 mm) 70–80%, and fine powder (≤0.088 mm) 15–20%. Waste silica bricks are processed into silica brick sand particles with a particle size of 0-2.2mm; Silica is washed with water, crushed, and then processed into fine silica powder with a particle size ≤0.088mm, and the mass percentage of particles with a particle size ≤0.088mm in the fine powder is ≥95%. Step S2, Ingredients and Mixing: The ingredients are proportioned by weight as follows: 40-70% silica sand particles, 10-30% silica brick sand particles, 18-30% fine silica powder, plus 0.2-0.8% mineralizer, 0.4-2.0% fluorite powder, 0.4-1.2% sintering binder, 0.5% organic binder, and 0.3-0.5% high-efficiency water-reducing agent JS. Place the above raw materials in an automatic batching system and mix for 20-25 minutes until the material is uniform; Step S3, molding: The uniformly mixed clay is pressed into shape using a semi-dry method. The molding method involves applying pressure to both the top and bottom surfaces of the clay using a brick press, controlling the apparent porosity of the brick blank to be ≤19.0% and the bulk density to be ≥2.10g / cm³. Step S4, Drying: The formed brick blanks are dried in a tunnel drying kiln. The inlet temperature of the drying hot air is 80-100℃, the outlet temperature is 50-70℃, the drying time is ≥48h, and the residual moisture of the dried brick blanks is ≤0.5%. Step S5, firing: The dried brick blanks are fired in a tunnel kiln, and the firing process includes: Preheating zone (room temperature ~ 1200℃): heating rate 8 ~ 20℃ / h; Firing zone (1200~1450℃): heating rate 12~14℃ / h, and holding at 1420~1450℃ for 18~36h; Cooling zone (1450℃~room temperature): The cooling rate is 35~50℃ / h in the 1450~800℃ range, and 10~15℃ / h in the 800℃ to room temperature range.

[0008] In some embodiments, in step S1, the silica is the main raw material, and its chemical composition satisfies the following: SiO2 content ≥ 99.0%, Al2O3 ≤ 0.4%, Fe2O3 ≤ 0.4%, CaO+MgO ≤ 0.25%, R2O < 0.2%.

[0009] In some embodiments, in step S2, the mineralizing agent is iron scale, the sintering binder is clay with an Al2O3 content of 25-35%, and the organic binder is an aqueous dextrin solution with a specific gravity of 1.12-1.18 g / cm³.

[0010] In some embodiments, in step S2, the order of adding materials during mixing is as follows: first, add a dry powder mixture of silica sand particles, silica brick sand particles, mineralizer, fluorite powder, sintering binder and high-efficiency water-reducing agent JS; then, add a liquid organic binder; and finally, add fine silica powder.

[0011] In some embodiments, in step S3, the grid brick blanks are pressed using a mold during molding.

[0012] In some embodiments, in step S5, during the heat preservation stage of 1420–1450°C in the firing zone, metastable cristobalite in the brick is induced to transform into α-tridymite, and the residual quartz content of the final product is controlled to be ≤1.0%.

[0013] In some embodiments, the brick press includes: The main hydraulic system drives the pressure head to perform the pressing action; A floating mechanism is located below the lower pressure head and has a lower die groove for cooperating with the lower pressure head to achieve bidirectional pressure. Rotating components and fabric components that rotate about the central axis of the lower mold groove.

[0014] In some embodiments, the fabric assembly includes: The cloth section is equipped with a feeding pipe for discharging mud. The movable component drives the outlet end of the feeding tube to move radially above the lower mold groove, so that the rotational motion of the rotating component and the radial movement of the movable component form a compound motion trajectory.

[0015] In some embodiments, the active component further includes a baffle corresponding to the feed pipe for dispersing the mud falling from the feed pipe; The rotating assembly causes the scraping layer on one side of the baffle to rotate and adhere to the surface of the lower pressure head, removing the adhering substances on the lower pressure head.

[0016] In some embodiments, the active component is further provided with a vibration component for transmitting mechanical vibration to the feed pipe during the material distribution process, thereby disrupting particle aggregation formed in the conveying path of the mud and promoting smooth and uniform discharge.

[0017] Compared with the prior art, the present invention provides a method for preparing silica check bricks for high-density, low-porosity hot blast stoves, which has the following beneficial effects.

[0018] 1. This invention, through optimized particle size distribution and the application of high-efficiency water-reducing agents, successfully prepares a green body with high bulk density and low apparent porosity, laying the foundation for the excellent heat storage capacity and structural strength of the final product, significantly improving the overall performance of the product, and meeting the stringent requirements of high-temperature hot blast stoves.

[0019] 2. This invention relies on a precisely controlled firing process, especially long-term heat preservation at 1420-1450℃, to strictly control the residual quartz content in the brick body to an extremely low level of ≤1.0%, fundamentally eliminating the risk of furnace body cracking caused by the later transformation of residual quartz, ensuring the long-term safe and stable operation of the hot blast stove, and achieving extremely high volume stability and ultra-long service life.

[0020] 3. The product prepared by this invention not only has a high load softening temperature, but also exhibits particularly outstanding high-temperature creep resistance, which is significantly improved compared to conventional products. This ensures that the checker bricks are not easily softened or deformed under high load and high temperature conditions, maintaining unobstructed airflow channels. It possesses excellent high-temperature structural strength and creep resistance.

[0021] 4. This invention uses waste silica brick sand as a volume-stable clinker, effectively buffering the crystal transformation expansion during raw material firing, significantly increasing the yield to over 95.5%, while reducing production costs and realizing the resource-based recycling of solid waste. By introducing waste silica brick sand, multiple goals of cost reduction, efficiency improvement, and green manufacturing are achieved.

[0022] 5. This invention forms a complete, efficient and controllable preparation technology system, from the design of raw material gradation and the water-reducing properties of high-efficiency water-reducing agents to the uniform molding of double-sided pressure and the gradient drying and firing process, ensuring the consistency and reliability of product performance.

[0023] 6. This invention reduces the molding moisture content from the conventional 6% to 4.5-5.0% by introducing a high-efficiency water-reducing agent JS, and uses a composite mineralizer composed of iron scale and fluorite powder. The two work synergistically to provide key technical support for achieving high-density molding of the green body and promoting the low-temperature and rapid crystal transformation of quartz.

[0024] Other advantages, objectives and features of the invention will be set forth in part in the description which follows; and in part will be apparent to those skilled in the art upon examination of the following description; or may be learned from practice of the invention. Attached Figure Description

[0025] Figure 1 This is the main process flow diagram of the present invention.

[0026] Figure 2 This is a schematic diagram of the raw material pretreatment process flow chart of the present invention.

[0027] Figure 3 This is a schematic diagram of the ingredient mixing process of the present invention.

[0028] Figure 4 This is a schematic diagram of the firing process of the present invention.

[0029] Figure 5 This is a schematic diagram of the brick press machine of the present invention.

[0030] Figure 6 For the present invention Figure 5 A magnified structural diagram of region A in the middle.

[0031] Figure 7 This is a schematic diagram of the structure of the rotating component and the fabric component of the present invention.

[0032] Figure 8 For the present invention Figure 7 Front view structural diagram.

[0033] Figure 9 For the present invention Figure 8 A schematic diagram of a local part of the structure.

[0034] Figure 10 For the present invention Figure 7 A schematic diagram of a local part of the structure.

[0035] Figure 11 This is a schematic diagram of the inner ring transmission structure of the present invention.

[0036] Figure 12 This is a schematic diagram of the structure of the active component of the present invention.

[0037] Figure 13 This is a schematic diagram of the structure of the vibration part of the present invention.

[0038] Figure 14 This is a structural schematic diagram of the cross-section of the active component of the present invention.

[0039] In the diagram: 1. Main hydraulic system; 101. Main hydraulic cylinder; 102. Support assembly; 2. Floating mechanism; 201. Fixed base; 202. Floating seat; 2021. Lower mold groove; 3. Support frame; 4. Lower pressure head; 5. Rotating assembly; 501. Outer ring; 502. Inner ring; 503. Drive motor; 6. Fabric placement assembly; 601. Storage box; 602. Feeding pipe; 603. Electric push rod; 604. Connecting rod ; 605, baffle; 6051, scraping layer; 606, vibrating part; 6061, base; 6062, connecting rib; 6063, lifting groove; 6064, first spring; 6065, first protrusion; 6066, second protrusion; 607, elastic part; 6071, connecting cylinder; 6072, movable plate; 6073, elastic pad; 6074, second spring; 6075, electromagnet; 6076, adsorption block. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0041] Reference Figures 1 to 4 A method for preparing silica check bricks for high-density, low-porosity hot blast stoves includes the following steps: Step S1, Raw material selection and pretreatment: Silica is washed, crushed, and pulverized to prepare silica sand particles with a particle size range of 0–2.2 mm. The particle size distribution is controlled as follows: coarse particles >2.0 mm account for ≤5.0%, medium particles 2.0–0.088 mm account for 70–80%, and fine powder ≤0.088 mm account for 15–20%. Waste silica bricks are processed into silica brick sand particles with a particle size of 0-2.2mm; silica is washed with water, crushed, and then processed into silica fine powder with a particle size ≤0.088mm, and the mass percentage of particles with a particle size ≤0.088mm in the fine powder is ≥95%; Among them, washing with water removes dirt and impurities from the surface of silica, improving the purity of raw materials and preventing impurities from forming too many low-melting substances at high temperatures, which would affect refractoriness and high-temperature performance. The number of coarse particles is relatively small. The coarse particles support each other in the brick body to form a strong "skeleton" to provide macroscopic structural strength and resistance to external forces and high-temperature creep. The medium-sized particles account for the largest proportion. They are used to fill the gaps between the coarse-particle skeleton, making the structure more compact and reducing large pores. The fine powder fills the smaller gaps between coarse and medium particles and can more effectively promote material migration and densification reaction during sintering by increasing the contact points between particles. This gradation process allows for the densest packing before molding, thereby minimizing initial porosity in the green body and providing a key physical basis for obtaining a structure with low porosity and high bulk density after firing.

[0042] The silica brick sand particles and silica fine powder are two functional materials. On the one hand, the silica brick sand is a pre-fired clinker with good volume stability, which buffers the crystal transformation and expansion of raw silica during the firing process, thereby reducing the risk of cracking. At the same time, its surface can act as a crystal nucleus to promote sintering. On the other hand, the silica fine powder, with its fine particle size, can effectively fill the micropores of the green body to increase the packing density. Its high specific surface area gives it high sintering activity, which helps to reduce the sintering temperature and drive the densification of the green body.

[0043] The main raw material is silica, and its chemical composition meets the following requirements: SiO2 content ≥ 99.0%, Al2O3 ≤ 0.4%, Fe2O3 ≤ 0.4%, CaO+MgO ≤ 0.25%, R2O < 0.2%.

[0044] Step S2, Ingredients and Mixing: The ingredients are prepared according to the following percentages by weight: 40-70% silica sand particles, 10-30% silica brick sand particles, 18-30% fine silica powder, plus 0.2-0.8% mineralizer, 0.4-2.0% fluorite powder, 0.4-1.2% sintering binder, 0.5% organic binder, and 0.3-0.5% high-efficiency water-reducing agent JS. The above raw materials are placed in an automatic batching system and mixed for 20-25 minutes until the material is uniform.

[0045] The mineralizing agent is iron scale, the sintering binder is clay with an Al2O3 content of 25-35%, and the organic binder is an aqueous solution of dextrin with a specific gravity of 1.12-1.18 g / cm³.

[0046] The order of adding materials during mixing is as follows: first add all the dry materials, including silica sand particles, silica brick sand particles, mineralizer, fluorite powder, sintering binder and high-efficiency water-reducing agent JS dry powder mixture, then add the liquid organic binder, and finally add the silica fine powder.

[0047] Place the above raw materials into an automatic batching system and mix for 20-25 minutes until the material is uniform and reaches the optimal state where it can be formed into a ball when squeezed in the hand, does not fall apart when shaken, and is not sticky to the hand.

[0048] Step S3, molding: The uniformly mixed clay is pressed into shape using a semi-dry method. The molding method involves applying pressure to both the top and bottom surfaces of the clay using a brick press, controlling the apparent porosity of the brick blank to be ≤19.0% and the bulk density to be ≥2.10g / cm³. Among them, irregular molds are used to press out checker brick blanks with through-hole structures during the forming process.

[0049] Step S4, Drying: The formed brick blanks are dried in a tunnel drying kiln that utilizes preheated hot air circulation. The inlet temperature of the drying hot air is 80-100℃, the outlet temperature is 50-70℃, the drying time is ≥48h, and the residual moisture content of the dried brick blanks is ≤0.5%. Step S5, firing: The dried brick blanks are fired in a tunnel kiln, and the firing process includes: Preheating zone from room temperature to 1200℃: heating rate 8-20℃ / h; Firing zone at 1200–1450℃: heating rate 12–14℃ / h, and holding at 1420–1450℃ for 18–36h; Cooling zone from 1450℃ to room temperature: The cooling rate is 35 to 50℃ / h in the 1450 to 800℃ range, and 10 to 15℃ / h in the 800℃ to room temperature range.

[0050] In step S5, during the heat preservation stage of 1420-1450℃ in the firing zone, the metastable cristobalite in the brick body is transformed into α-tridymite, and the residual quartz content of the final product is controlled to be ≤1.0%.

[0051] Table 1 shows the performance indicators of this product.

[0052] Table 1 As shown in Table 1, this product has excellent comprehensive properties, including high bulk density, low apparent porosity, extremely high high temperature structural stability, and extremely low residual quartz content.

[0053] This invention also discloses a high-density, low-porosity silica checker brick, prepared using the above-described method. The high-density, low-porosity silica checker brick exhibits the following performance characteristics: bulk density ≥ 1.83 g / cm³, apparent porosity ≤ 21%, room temperature compressive strength ≥ 40 MPa, softening temperature under 0.2 MPa load (T0.6) ≥ 1660℃, permanent linear shrinkage rate under heating (1500℃ × 5h) ± 0.2%, and creep rate under 0.2 MPa load (1550℃, 0-50h) ≤ 0.3%.

[0054] Table 2 compares the key performance indicators of the product of this invention with those of the industry standard (RG-95) checker bricks.

[0055] Table 2 Table 3 shows a comparison of the preparation effects of the present invention and conventional processes.

[0056] Table 3 In summary, compared with the prior art, the present invention has the following outstanding features and beneficial effects: 1. By optimizing particle size distribution and applying high-efficiency water-reducing agent, a green body with high bulk density (≥1.83 g / cm³) and low apparent porosity (≤21%) was successfully prepared, laying the foundation for the excellent heat storage capacity and structural strength of the final product, significantly improving the overall performance of the product and meeting the stringent requirements of high-temperature hot blast stoves.

[0057] 2. Relying on a precisely controlled firing process, especially long-term heat preservation at 1420-1450℃, the residual quartz content in the brick body is strictly controlled at an extremely low level of ≤1.0%, which fundamentally eliminates the risk of furnace body cracking caused by the later transformation of residual quartz, ensuring the long-term safe and stable operation of the hot blast stove and achieving extremely high volume stability and ultra-long service life.

[0058] 3. The product not only has a high load softening temperature (T0.6 ≥1660℃), but also outstanding high-temperature creep resistance (1550℃, 50h, creep rate ≤0.3%), which is significantly improved compared to conventional products. This ensures that the checker bricks are not easily softened or deformed under high load and high temperature conditions, maintaining unobstructed airflow channels. It possesses excellent high-temperature structural strength and creep resistance.

[0059] 4. Waste silica brick sand, as a volume-stable clinker, effectively buffers the crystal transformation expansion during raw material firing, significantly increasing the yield to over 95.5%, while reducing production costs and realizing the resource-based recycling of solid waste. By introducing waste silica brick sand, multiple goals of cost reduction, efficiency improvement, and green manufacturing have been achieved.

[0060] 5. From the design of raw material gradation and the water-reducing properties of high-efficiency water-reducing agents to the uniform molding under double-sided pressure and the gradient drying and firing process, a complete, efficient and controllable preparation technology system has been formed, ensuring the consistency and reliability of product performance.

[0061] 6. By introducing the high-efficiency water-reducing agent JS, the molding moisture content is reduced from the conventional 6% to 4.5-5.0%. A composite mineralizer composed of iron scale and fluorite powder is used. The two work synergistically to provide key technical support for achieving high-density molding of the green body and promoting the low-temperature and rapid crystal transformation of quartz.

[0062] Please see Figures 5 to 14The present invention also discloses a brick press, which is used for pressing and molding the clay material in step 3 above. The brick press includes a main hydraulic system 1, a floating mechanism 2, and a support frame 3. The main hydraulic system 1 is located on the top of the support frame 3 and includes a main hydraulic cylinder 101 and a support assembly 102. The support assembly 102 limits and supports the main hydraulic cylinder 101. The telescopic end of the main hydraulic cylinder 101 passes through the middle of the support frame 3 and is provided with a lower pressing head 4. The floating mechanism 2 is located below the lower pressing head 4 and includes a fixed base 201 and a floating seat 202. The middle of the floating seat 202 is provided with a lower mold groove 2021 that is adapted to the lower pressing head 4.

[0063] In use, mud is filled into the lower mold groove 2021, and the main hydraulic cylinder 101 drives the lower pressure head 4 to press downwards. Before the lower pressure head 4 contacts the mud in the lower mold groove 2021, the lower hydraulic cylinder below the floating seat 202 applies an upward, constant back pressure to the floating seat 202, which supports the floating seat 202. After the lower pressure head 4 contacts the mud, the downward pressure must first overcome the back pressure to make the floating seat 202 sink. Vent holes are provided inside the lower pressure head 4 or the lower mold groove 2021. During the process of the lower pressure head 4 overcoming the upward back pressure of the lower hydraulic cylinder, the gas in the material is discharged through the vent holes, making the material initially compacted. Next, the displacement sensor detects when the floating seat 202 moves down to the preset position. The valve of the lower hydraulic cylinder remains closed, and the hydraulic oil is sealed inside the cylinder and cannot flow. The floating seat 202 changes from a floating state to a locked state. Then, the main hydraulic cylinder 101 applies a preset high pressure downward to the mud material. This high pressure acts entirely on the mud material, compacting it from both top and bottom directions. This completes the processing of the brick blank.

[0064] However, in actual use, operators found that although the main hydraulic cylinder 101 and the lower hydraulic cylinder can initially compact the clay and compress and expel most of the gas in the clay, when the clay is distributed into the lower mold groove 2021, if there is more material in the center and less at the edges, the resulting brick blank after pressing will have extremely high density in the center and insufficient density at the edges. This inherent density gradient will directly lead to deformation or cracking during firing due to uneven shrinkage. Therefore: The support frame 3 has a rotating assembly 5 and a fabric assembly 6 on its inner side. The rotating assembly 5 includes an outer ring 501 and an inner ring 502, which are rotatably connected to the outer ring 501. The outer ring 501 is equipped with a drive motor 503 and a rack in the circumferential direction. The rotating end of the drive motor 503 is equipped with a gear. The drive motor 503 drives the inner ring 502 to rotate through the gear and the ring rack. The outer ring 501 is fixedly connected to the support frame 3. The fabric assembly 6 is located on one side of the inner ring 502. The fabric assembly 6 includes a fabric part and a movable component. The fabric part is located above the pusher top. The system includes a storage bin 601, with a feeding pipe 602 on one side; the storage bin 601 is fixedly connected to an inner ring 502; the movable component includes an electric push rod 603 fixedly connected to the inner ring 502, with a baffle 605 connected to the telescopic end of the electric push rod 603; the bottom end of the feeding pipe 602 is fixedly connected to one end of a connecting rod 604; the movable component is equipped with a vibration assembly for the feeding pipe 602; the vibration assembly includes a vibration part 606, a connecting rod 604 located between the telescopic end of the electric push rod 603 and the baffle 605, and an elastic part 607; the vibration part 606... The base 6061 is fixedly connected to the inner ring 502 via a connecting rib 6062. A lifting groove 6063 is provided in the middle of the base 6061. A first spring 6064 is provided at the bottom of the lifting groove 6063, and a first protrusion 6065 is provided at the top of the first spring 6064, which slides and is limited within the lifting groove 6063. A second protrusion 6066, corresponding to and cooperating with the first protrusion 6065, is provided at the bottom of the connecting rod 604. Multiple second protrusions 6066 are provided. The elastic part 607 includes a connecting cylinder fixedly connected to the telescopic end of the electric push rod 603. 6071, A movable plate 6072 is fixedly connected to one end of the connecting rod 604 near the connecting cylinder 6071, and is horizontally slidably connected inside the connecting cylinder 6071. An elastic pad 6073 is provided on the edge of the movable plate 6072. The movable plate 6072 is fixedly connected to the inside of the connecting cylinder 6071 by a second spring 6074. An electromagnet 6075 is provided inside the connecting cylinder 6071. An adsorption block 6076 corresponding to and cooperating with the electromagnet 6075 is provided in the middle of the movable plate 6072. The electromagnet 6075 and the adsorption block 6076 correspond to the middle of the second spring 6074.

[0065] In use, the mud is stored in the storage bin 601. A control valve is installed on the feeding pipe 602 to control the amount of mud discharged outward through the feeding pipe 602. When discharging into the lower mold groove 2021, the control valve on the feeding pipe 602 is activated, and the uniformly mixed mud in the storage bin 601 is conveyed into the lower mold groove 2021 through the feeding pipe 602. At the same time, the switches of the drive motor 503 and the electric push rod 603 are activated. The drive motor 503 drives the push rod through gears and... The annular rack on the outer side of the inner ring 502 drives the inner ring 502 to rotate. The electric push rod 603 repeatedly extends and retracts, driving the bottom end of the feeding pipe 602 to move back and forth via the connecting rod 604. This allows the bottom end of the feeding pipe 602 to move from the edge of the lower mold groove 2021 to the center and then from the center back to the edge, coordinated with the continuous rotation of the inner ring 502. As the inner ring 502 rotates once, a layer of clay is laid into the lower mold groove 2021 through the feeding pipe 602. This bottom-up method completes the laying of clay in the lower mold groove 2021, improving the uniformity of clay distribution and preventing uneven, clumped distribution. After the clay is laid in the lower mold groove 2021, the electric push rod 603 and the inner ring 502 return to their original positions.

[0066] Furthermore, although the clay particle size is small, under storage and its own weight, fine powder particles are prone to adsorption and agglomeration, forming secondary agglomerates larger than single particles. Simultaneously, particles of different sizes may exhibit localized concentration during flow. All of these factors disrupt the uniformity of the clay, causing uneven material accumulation during distribution, forming hidden pores and density gradients. Ultimately, this leads to uneven density, delamination, or firing deformation in the brick blank after pressing. To address this, during the back-and-forth movement of the bottom end of the feeding pipe 602 driven by the electric push rod 603, multiple second protrusions 6066 at the bottom of the connecting rod 604 slide back and forth past the first protrusion 6065. The diameter of the movable plate 6072 is smaller than the inner diameter of the connecting cylinder 6071. As the multiple second protrusions 6066 pass the first protrusion 6065, The first protrusion 6065 causes the connecting rod 604 to vibrate repeatedly as it moves up and down, thereby driving the bottom end of the feeding pipe 602 to move up and down. This continuously disrupts the aggregation of larger particles that have formed along the mud flow path. Utilizing the inertia of the mud during discharge, it contacts the baffle 605, causing the mud particles to undergo secondary rearrangement before falling into the lower mold groove 2021, further improving the looseness and uniformity of the mud particle distribution within the lower mold groove 2021. Simultaneously, the vibration of the feeding pipe 602 maintains smooth mud discharge and prevents material interruption. This provides a foundation for achieving a denser natural accumulation in the lower mold groove 2021, improving the densification efficiency and uniformity of the blank in subsequent pressing processes.

[0067] The connecting rod 604 is connected to the feeding tube 602 by an elastic column. The elastic column is used to buffer and absorb the lateral and longitudinal impact forces generated by the feeding tube 602 during vibration and movement, so as to avoid structural fatigue damage caused by rigid connection, and at the same time ensure that the vibration energy can be transmitted to the feeding tube 602 in a gentler and more efficient way, maintaining its stable working state.

[0068] Furthermore, after the main hydraulic cylinder 101 drives the lower pressure head 4 to press the clay material in the lower mold groove 2021 into shape, the product is taken out from the lower mold groove 2021. For example, an ejection mechanism for the product is set at the bottom of the lower mold groove 2021. When the main hydraulic cylinder 101 drives the lower pressure head 4 to move upward, the ejection mechanism pushes the processed product in the lower mold groove 2021 upward and removes the product. Then, the main hydraulic cylinder 101 drives the lower pressure head 4 to move downward, so that the lower pressure head 4 corresponds to the position of the scraping layer 6051. Then, the switch of the electric push rod 603 is first activated. The extension end of the electric push rod 603 drives the scraping layer 6051 to stick tightly to the outside of the lower pressure head 4. As the extension end of the electric push rod 603 extends further, the first protrusion 6065 and the second protrusion 6066 disengage and connect. Rod 604 is kept horizontal, and then movable plate 6072 is pressed into the connecting cylinder 6071. The second spring 6074 is compressed, and electromagnet 6075 contacts adsorption block 6076. By energizing electromagnet 6075, electromagnet 6075 and adsorption block 6076 are magnetically fixed together, and connecting cylinder 6071 and connecting rod 604 form an integral structure. Then, the distance between scraping layer 6051 and the outer side of lower pressure head 4 can be adjusted by electric push rod 603 to maintain contact between scraping layer 6051 and the outer side of lower pressure head 4. Then, drive motor 503 is started, and lower pressure head 4 is located at the center of inner ring 502. At this time, during the rotation of inner ring 502, scraping layer 6051 rotates close to the outer side of lower pressure head 4 to clean the circumference of lower pressure head 4, which is used to clean stubborn scale on the circumference of lower pressure head 4.

[0069] Furthermore, the scraping layer 6051 is detachably connected to the baffle 605. The scraping layer 6051 can be selected with different thicknesses, for example, the thickness of the scraping layer 6051 can cover at least half of the maximum diameter of the lower pressure head 4. At this time, after the inner ring 502 rotates once and the scraping layer 6051 has finished cleaning the outside of the lower pressure head 4, the main hydraulic cylinder 101 drives the lower pressure head 4 to move upward, so that the upper surface of the scraping layer 6051 is in contact with the lower surface of the lower pressure head 4. Then, it continues to extend forward through the telescopic end of the electric push rod 603, so that the upper surface of the scraping layer 6051 covers at least half of the lower surface of the lower pressure head 4. Then, the drive motor 503 is started again and drives the inner ring 502 to rotate, so that the upper surface of the scraping layer 6051 cleans the stubborn scale on the lower surface of the lower pressure head 4.

[0070] To improve production efficiency, a dust collection component is installed, with its suction port corresponding to the scraping layer 6051. When the surface of the lower pressing head 4 is cleaned by the scraping layer 6051, falling impurities are sucked in and collected by the suction port. On the other hand, during the cyclic pressing of the brick blank, after each pressing, the high-pressure suction of the dust collection component first cleans the loose adhering substances on the surface of the lower pressing head 4. When stubborn scale buildup occurs on the surface of the lower pressing head 4, the aforementioned scraping layer 6051 is activated for contact scraping cleaning of the lower pressing head 4. In addition, as an optional solution, the telescopic end of the ejection mechanism in the lower mold groove 2021 is fixedly connected to the bottom plate of the lower mold groove 2021. After the brick blank is pressed and formed, the ejection mechanism extends upward to push the bottom plate of the lower mold groove 2021 and the brick blank upward. When the bottom plate is pushed upward, the stubborn scale on the inner wall of the lower mold groove 2021 is also pushed upward. At the same time, the suction port of the dust collection component performs dust collection and cleaning on the product pushed upward and the bottom plate of the lower mold groove 2021. After cleaning, the ejection mechanism drives the bottom plate to reset.

[0071] 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.

[0072] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A method for preparing silica checker bricks for a high-density, low-porosity hot blast stove, characterized in that, Includes the following steps: Step S1, Raw material selection and pretreatment: Silica is washed, crushed, and pulverized to prepare silica sand particles with a particle size range of 0–2.2 mm. The particle size distribution is controlled as follows: coarse particles >2.0 mm account for ≤5.0%, medium particles 2.0–0.088 mm account for 70–80%, and fine powder ≤0.088 mm account for 15–20%. Waste silica bricks are processed into silica brick sand particles with a particle size of 0-2.2mm; Silica is washed with water, crushed, and then processed into fine silica powder with a particle size ≤0.088mm, and the mass percentage of particles with a particle size ≤0.088mm in the fine powder is ≥95%. Step S2, Ingredients and Mixing: The ingredients are proportioned by weight as follows: 40-70% silica sand particles, 10-30% silica brick sand particles, 18-30% fine silica powder, plus 0.2-0.8% mineralizer, 0.4-2.0% fluorite powder, 0.4-1.2% sintering binder, 0.5% organic binder, and 0.3-0.5% high-efficiency water-reducing agent JS. Place the above raw materials in an automatic batching system and mix for 20-25 minutes until the material is uniform; Step S3, molding: The uniformly mixed clay is pressed into shape using a semi-dry method. The molding method involves applying pressure to both the top and bottom surfaces of the clay using a brick press, controlling the apparent porosity of the brick blank to be ≤19.0% and the bulk density to be ≥2.10g / cm³. Step S4, Drying: The formed brick blanks are dried in a tunnel drying kiln. The inlet temperature of the drying hot air is 80-100℃, the outlet temperature is 50-70℃, the drying time is ≥48h, and the residual moisture of the dried brick blanks is ≤0.5%. Step S5, firing: The dried brick blanks are fired in a tunnel kiln, and the firing process includes: Preheating zone from room temperature to 1200℃: heating rate 8-20℃ / h; Firing zone at 1200–1450℃: heating rate 12–14℃ / h, and holding at 1420–1450℃ for 18–36h; Cooling zone from 1450℃ to room temperature: The cooling rate is 35 to 50℃ / h in the 1450 to 800℃ range, and 10 to 15℃ / h in the 800℃ to room temperature range.

2. The method for preparing silica check bricks for a high-density, low-porosity hot blast stove according to claim 1, characterized in that, In step S1, the silica is the main raw material, and its chemical composition meets the following requirements: SiO2 content ≥ 99.0%, Al2O3 ≤ 0.4%, Fe2O3 ≤ 0.4%, CaO+MgO ≤ 0.25%, R2O < 0.2%.

3. The method for preparing silica check bricks for a high-density, low-porosity hot blast stove according to claim 1, characterized in that, In step S2, the mineralizing agent is iron scale, the sintering binder is clay with an Al2O3 content of 25-35%, and the organic binder is an aqueous solution of dextrin with a specific gravity of 1.12-1.18 g / cm³.

4. The method for preparing silica check bricks for a high-density, low-porosity hot blast stove according to claim 1, characterized in that, In step S2, the order of adding materials during mixing is as follows: first, add a dry powder mixture of silica sand particles, silica brick sand particles, mineralizer, fluorite powder, sintering binder and high-efficiency water-reducing agent JS; then add a liquid organic binder; and finally add fine silica powder.

5. The method for preparing silica check bricks for a high-density, low-porosity hot blast stove according to claim 1, characterized in that, In step S3, the grid brick blanks are pressed using a mold during the forming process.

6. The method for preparing silica check bricks for a high-density, low-porosity hot blast stove according to claim 1, characterized in that, In step S5, during the heat preservation stage of 1420-1450℃ in the firing zone, the metastable cristobalite in the brick body is transformed into α-tridymite, and the residual quartz content of the final product is controlled to be ≤1.0%.

7. A method for preparing silica check bricks for a high-density, low-porosity hot blast stove according to any one of claims 1-6, characterized in that, The brick press includes: The main hydraulic system (1) drives the lower pressure head (4) to perform the pressing action; A floating mechanism (2) is located below the lower pressure head (4) and is provided with a lower mold groove (2021) for cooperating with the lower pressure head (4) to achieve bidirectional pressure. Rotating assembly (5) and fabric assembly (6) that rotate about the central axis of the lower mold groove (2021).

8. The method for preparing silica check bricks for a high-density, low-porosity hot blast stove according to claim 7, characterized in that, The fabric assembly (6) includes: The cloth section is equipped with a feed pipe (602) for discharging mud. The movable component drives the outlet end of the feed tube (602) to move radially above the lower mold groove (2021), so that the rotational motion of the rotating component (5) and the radial movement of the movable component form a compound motion trajectory.

9. The method for preparing silica check bricks for a high-density, low-porosity hot blast stove according to claim 1, characterized in that, The active component also includes a baffle (605) corresponding to the feed pipe (602) for dispersing the mud falling from the feed pipe (602); The rotating component (5) drives the scraping layer (6051) on one side of the baffle (605) to rotate and adhere to the surface of the lower pressure head (4) to remove the adhering substances on the lower pressure head (4).

10. The method for preparing silica check bricks for a high-density, low-porosity hot blast stove according to claim 1, characterized in that, The active component is also equipped with a vibration component, which is used to transmit mechanical vibration to the feeding pipe (602) during the material distribution process, thereby breaking up the particle aggregation formed by the mud in the conveying path and ensuring smooth and uniform discharge.

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