A comprehensive treatment process for resource utilization of post-use refractory materials

Abstract

The present application belongs to the field of refractory material resource utilization, and particularly relates to a comprehensive treatment process for resource utilization of used refractory materials, which comprises: pretreatment, wherein the used refractory materials are sorted, surface cleaned and impurities removed to obtain raw materials for recycling; the raw materials are sequentially subjected to primary coarse crushing, secondary medium crushing, tertiary fine crushing and matched closed circuit screening to obtain crushed materials with target particle size; the qualified particle size materials are sent into a hydration and drying integrated equipment, and after hydration in a water vapor environment, vacuum drying is performed; the dried materials are sent into a wheel milling equipment through a quantitative feeder set, and selective crushing of pseudo-particles is performed under an applied pressure of 15-25 MPa, and finally, classification screening is performed to obtain regenerated materials with different particle size specifications. The process has the advantages that: the step-by-step accurate refinement from large waste materials to target particle size is realized, the particle size is accurately controlled, and the aggregate loss rate is effectively reduced. Compared with traditional single-stage or two-stage crushing, the over-crushing phenomenon is effectively controlled, and the aggregate recovery rate is improved.

Description

Technical Field

[0001] This invention belongs to the field of refractory material resource utilization, and in particular relates to a comprehensive treatment process for the resource utilization of used refractory materials. Background Technology

[0002] With the rapid development of industries such as metallurgy and building materials, a large amount of used refractory materials (such as magnesia-carbon bricks and alumina-carbon bricks) are generated. If these materials can be effectively recycled and reused, it can not only save resources and reduce environmental pollution, but also reduce the production costs of enterprises. At present, the resource utilization of used refractory materials has become a research hotspot in the industry, but existing technologies still have many problems in the processing, especially in the areas of pseudo-particle removal, equipment connection, and hydration treatment, which urgently need improvement.

[0003] In the crushing and processing of used refractory materials, existing technologies mostly employ multi-stage crushing processes. For example, patent publication number CN111744632A discloses a pre-crushing process for hard ceramic raw materials. This process uses a four-stage crushing plus two-stage screening method, involving four stages: coarse crushing, medium crushing, fine crushing, and ultrafine crushing, combined with primary and secondary screening. This achieves the effect of more crushing and less grinding, improving crushing efficiency and slurry quality. Patent publication number CN108940528A proposes a highly efficient ore crushing process and its crushing system, including a coarse crushing device, a medium crushing device, a first fine crushing device, and a second fine crushing device. By screening the ore particles and then crushing them in stages, the crushing efficiency and effect are improved.

[0004] Regarding closed-loop crushing and screening, existing technologies include patent application WO2024153015A1, which describes a method and system for efficient ore crushing, grinding, and sorting. This method involves sequentially coarsely crushing, medium crushing, and screening of the raw ore, with the oversize product returned to the medium crushing unit. The undersize product is fed to a high-pressure roller mill for high-pressure roller grinding and screening, with the oversize product returned to the high-pressure roller mill, forming a closed-loop system. Patent publication CN109158202A discloses a crushing-screening-washing process for high-mud, high-water surface mixed hematite, employing a medium-pressure cone crusher-dry double-layer vibrating screen closed-loop treatment, effectively solving the problem of mineral adhesion and clogging.

[0005] In terms of material classification and processing, patent publication number CN113333152A proposes a mineral processing pre-selection process for the comprehensive utilization of ultra-lean iron ore tailings waste rock, including coarse crushing-first-stage dry pre-selection-screening operation and fine crushing-second-stage wet pre-selection-grading operation. The tailings of the first-stage dry pre-selection are screened into multiple particle size aggregates by vibrating screen, realizing the comprehensive utilization of resources.

[0006] However, existing post-use refractory material recycling processes still have the following technical problems: First, the removal of false particles is incomplete. Existing processes mostly use single crushing or ball milling, which cannot effectively distinguish and remove false particles. If these particles are mixed into recycled aggregates, they will significantly reduce the bulk density, mechanical strength, and thermal shock stability of recycled refractory products, causing recycled materials to be downgraded for use in low-end fields and unable to meet the raw material standards for medium and high-grade refractory materials.

[0007] Secondly, the equipment has poor interoperability. Traditional single-stage or multi-stage crushing without closed-circuit screening results in uneven particle size distribution of materials, incomplete crushing or over-crushing, which not only leads to serious loss of effective aggregate and low resource recovery rate, but also affects the removal of impurities and false particles, thus having a significant impact on screening efficiency and screening quality.

[0008] Third, the hydration treatment is unreasonable. The traditional hydration method in the resource utilization of used refractory materials is the immersion method in hydration tanks. However, this method generally faces problems such as large footprint of hydration tanks, long hydration time, high degree of manual intervention, need for waste liquid treatment, and irritating odor. This not only increases investment costs but also leads to a deterioration of the working environment.

[0009] Furthermore, existing technologies mostly focus on solving single problems, lacking a comprehensive processing technology that can synergistically address the two core challenges of physical separation of pseudo-particles and effective removal of active additives, while also ensuring precise particle size control. Therefore, there is an urgent need to develop a highly efficient, environmentally friendly, and comprehensive processing technology for the resource utilization of used refractory materials that can fully solve the aforementioned problems. Summary of the Invention

[0010] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a comprehensive treatment process for the resource utilization of used refractory materials that is efficient, environmentally friendly, and achieves a high resource utilization rate. This process solves the technical problems of incomplete removal of false particles, poor equipment integration, and unreasonable hydration treatment in existing used refractory material resource utilization processes. It achieves precise particle size control, synergistic impurity removal to improve the purity of recycled materials, and a green and environmentally friendly process without secondary pollution, thereby improving the resource utilization rate.

[0011] To achieve the above objectives, the present invention provides the following technical solution: A comprehensive processing technology for the resource utilization of used refractory materials includes the following steps sequentially connected by a conveying device: 1) Pretreatment: After the used refractory materials are pretreated by sorting and surface cleaning to remove impurities, the used refractory materials are recycled. 2) Three-stage crushing and closed-circuit screening: The pre-treated refractory raw materials are subjected to primary coarse crushing, secondary medium crushing and tertiary fine crushing in sequence, and closed-circuit screening is performed after fine crushing. Unqualified materials after screening are returned to the crushing feed silo for recycling crushing, and qualified materials enter the next process to obtain crushed materials of the target particle size. 3) Hydration and drying: Materials of qualified particle size are fed into an integrated hydration and drying equipment. After the materials are fully hydrated and dried, dried materials are obtained. 4) Roller mill: The dried material is fed into the roller mill through a quantitative feeder unit for crushing and selectively crushing false particles to obtain material with de-false particles; 5) Grading and screening: The de-fake granular material is fed into a multi-layer vibrating screen for grading and screening to obtain recycled refractory materials of different particle sizes. The material on the screen is returned to the roller mill for recycling.

[0012] The primary coarse crushing uses a jaw crusher to crush the pre-treated material to 50-80mm using the compression principle; the secondary medium crushing uses a jaw crusher or cone crusher to crush the material to 20-50mm; the tertiary fine crushing uses a double roll crusher or impact crusher to refine the material to the target particle size, and the screen aperture size of the matching closed-circuit screen is consistent with the required maximum particle size.

[0013] In step 3), the material entering the hydration and drying integrated equipment is first fully hydrated in a steam environment at 120-140℃ to hydrolyze compounds such as aluminum nitride and aluminum carbide in the material; then it is heated to 55-75℃ in a vacuum environment for drying to obtain dried material with a moisture content ≤0.5%. The total residence time of the material in the hydration and drying integrated equipment is 20-30 minutes.

[0014] In step 4), the roller mill uses a hydraulic pressurization system to apply a pressure of 15-25 MPa to the material.

[0015] The integrated hydration and drying equipment is a stacked disc vacuum dryer.

[0016] The vibration frequency of each section of the vibrating screen is 25~35Hz when unloaded, 45~55Hz when feeding, and increases to 65~75Hz when blocked.

[0017] The quantitative feeder unit consists of a manual gate valve, a screw conveyor, and a weighing system. The manual gate valve is used to adjust the feed rate to the screw conveyor, and the weighing system is used to weigh the material conveyed from the screw conveyor to the roller mill, thereby adjusting the feed rate of the roller mill.

[0018] The used refractory material is an oxide-carbon composite refractory material salvaged from the lining of an industrial kiln.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention employs a three-stage crushing process—coarse crushing, medium crushing, and fine crushing—combined with a closed-circuit screening system. This achieves precise refinement of large waste materials into target particle sizes, accurately controlling particle size and effectively reducing aggregate loss. Compared to traditional single-stage or two-stage crushing, it effectively controls over-crushing and improves aggregate recovery rate.

[0020] 2. This invention organically combines wheel milling with integrated hydration and drying, forming a dual purification mechanism of physical separation and chemical transformation, thereby improving the purity of recycled materials. Wheel milling utilizes the strength difference between genuine and counterfeit particles to achieve efficient removal of counterfeit particles, while hydration and drying hydrolyzes highly active aluminum nitride and aluminum carbide compounds, improving the chemical stability of the refractory material after use.

[0021] 3. The integrated water-drying equipment of the present invention has no wastewater discharge. It uses electricity to heat water to generate steam to hydrate materials. Excess water vapor is condensed by a condensing device and recycled. Dust is effectively collected by a dust removal system.

[0022] 4. The recycled material prepared using the process of this invention has stable product quality, and its bulk density, mechanical strength and thermal shock stability all meet the requirements, making it a high-quality refractory raw material. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] Figure 2 This is a production process flow diagram of the present invention.

[0025] In the diagram: 1. Used refractory material; 2. Crushing and feeding bin; 3. Three-stage crushing device; 4. Closed-circuit screening device; 5. Drying bin; 6. Hydration and drying integrated equipment; 7. Roller mill feeding bin; 8. Quantitative feeder unit; 9. Roller mill equipment; 10. Multi-layer vibrating screen; 11. Recycled material finished product bin. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0027] See Figure 1 , Figure 2 A comprehensive processing technology for the resource utilization of used refractory materials includes the following steps sequentially connected by a conveying device: 1) Pretreatment: After the oxide-carbon composite refractory material removed from the kiln lining is pretreated by sorting, surface cleaning and impurity removal, etc., the recycled refractory material raw material is obtained. 2) Three-stage crushing and closed-circuit screening: The pre-treated refractory raw materials are subjected to primary coarse crushing, secondary medium crushing and tertiary fine crushing in sequence, and closed-circuit screening is performed after fine crushing. Unqualified materials after screening are returned to the crushing feed silo for recycling crushing, and qualified materials enter the next process to obtain crushed materials of the target particle size. The primary crushing stage uses a jaw crusher to crush the pre-treated material to 50-80mm using the compression principle; the secondary crushing stage uses a jaw crusher or cone crusher to crush the material to 20-50mm; and the tertiary crushing stage uses a roller crusher or impact crusher to refine the material to the target particle size. The screen aperture size of the matching closed-circuit screening is consistent with the required maximum particle size. By reducing the single-machine load through three-stage crushing, minimizing over-grinding through closed-circuit circulation, and adjusting parameters in real time to adapt to material fluctuations, a balance between efficient crushing and precise particle size control is achieved.

[0028] 3) Hydration and Drying: Materials of the appropriate particle size are fed into an integrated hydration and drying system to remove active additive byproducts such as aluminum nitride and aluminum carbide present in the used refractory material. After thorough hydration and drying, the material is obtained as a dried product. The core equipment of the integrated hydration and drying system is a stacked disc vacuum dryer. Its internal central horizontal shaft has a heated lifting device, which can be driven by a motor to rotate and continuously agitate the internal materials. The integrated hydration and drying system uses electricity to heat water to generate steam for hydrating the materials. Excess steam is condensed and recycled, and the generated dust is collected by a dust removal system.

[0029] The material entering the hydration and drying integrated equipment is first fully hydrated in a steam environment at 120-140℃, causing the aluminum nitride, aluminum carbide and other compounds in the material to hydrolyze; then it is heated to 55-75℃ in a vacuum environment for drying, to obtain a dried material with a moisture content of ≤0.5%. The total residence time of the material in the hydration and drying integrated equipment is 20-30 minutes.

[0030] 4) Roller mill: The dried material is fed into the roller mill equipment (roller mill) through a quantitative feeder unit for rolling treatment, selectively crushing false particles to obtain material with de-false particles; The roller mill is a type of roller mill that uses a hydraulic pressurization system. The roller pressure is set based on the strength difference between real and fake particles: fake particles have a Mohs hardness of 4 to 5 and a critical stress of 8 to 15 MPa for crushing, while real particles have a Mohs hardness of 7 to 8 and a critical stress of 80 to 120 MPa for crushing; therefore, the roller mill is set to apply a pressure of 15 to 25 MPa to the material.

[0031] 5) Grading and screening: The de-fake granular material is fed into a multi-layer vibrating screen for grading and screening to obtain recycled refractory materials of different particle sizes. The material on the screen is returned to the roller mill for recycling.

[0032] The vibration frequency of each section of the vibrating screen is 25~35Hz when unloaded, 45~55Hz when feeding, and increases to 65~75Hz when blocked.

[0033] The integrated hydration and drying equipment is a fully enclosed horizontal cylindrical structure. Its internal central horizontal shaft is equipped with a heated lifting device, which is driven by a motor to rotate and continuously agitate the internal materials. The equipment uses electricity to heat water to generate steam for hydrating the materials. Excess steam is condensed and recycled, while the generated dust is collected by a dust removal system.

[0034] The quantitative feeder unit consists of a manual gate valve, a screw conveyor, and a weighing system. The manual gate valve is used to adjust the feed rate to the screw conveyor, and the weighing system is used to weigh the material conveyed from the screw conveyor to the roller mill. The combination of the screw conveyor and the weighing system ensures the accuracy of feeding the roller mill and guarantees the stable operation of the roller mill.

[0035] See Figure 1 The comprehensive processing system for the resource utilization of used refractory materials includes, in sequence, a crushing and feeding silo, a three-stage crushing device, a closed-circuit screening device, a drying silo, an integrated hydration and drying device, a roller mill feeding silo, a quantitative feeder unit, a roller mill, a multi-layer vibrating screen, and a recycled material finished product silo. Pre-treated used refractory materials are temporarily stored in the crushing and feeding silo, then fed into the three-stage crushing device for crushing, followed by screening by the closed-circuit screening device. Materials of qualified particle size are sent to the drying silo, while materials of unqualified particle size are sent back to the crushing and feeding silo for secondary crushing. Materials of qualified particle size in the drying silo are fed into the integrated hydration and drying device, where hydration and drying occur, causing the hydrolysis of compounds such as aluminum nitride and aluminum carbide in the material. The material is then heated to 55–75°C under vacuum for further drying, yielding dried material with a moisture content ≤0.5%. The dried material is fed into the roller mill feeding hopper, and then from there, via a quantitative feeder unit, it is fed into the roller mill equipment for crushing and grinding false particles to obtain de-false particle material. This de-false particle material is then fed into a multi-layer vibrating screen for grading and screening to obtain recycled refractory materials of different particle sizes, which are then sent to the recycled material finished product silo. The material exceeding the screen size is returned to the roller mill feeding hopper and fed back into the roller mill equipment for further recycling. This system operates under fully enclosed negative pressure. All equipment is connected in a closed loop, and the integrated hydration and drying equipment is connected to a dust removal system. Under the action of the dust removal system, the entire system operates under negative pressure, ensuring smooth material transport, reducing the risk of blockage, and preventing material leakage. This system is environmentally friendly and produces no secondary pollution.

[0036] Example 1:

[0037] This embodiment provides a comprehensive treatment process for the resource utilization of used refractory materials, using recycled magnesia-carbon bricks from steel ladles in the metallurgical industry as the raw material. The specific treatment process is as follows: 1) Preprocessing Oil and metallurgical slag on the surface of used steel ladle magnesia-carbon bricks are removed using high-pressure water jet cleaning. Non-recyclable impurities are then removed through manual sorting, yielding pretreated raw materials. During pretreatment, the water jet pressure is controlled at 3–5 MPa to ensure thorough removal of surface contaminants without damaging the refractory material itself.

[0038] 2) Three-stage crushing and closed-circuit screening The pretreated used ladle magnesia-carbon bricks are fed into a PE750×1060 jaw crusher for primary coarse crushing. The crusher has a feed opening of 750mm×1060mm and a discharge opening of 100mm, yielding coarse crushed material of 50-80mm. The matching motor power is 110kW. After coarse crushing, the used ladle magnesia-carbon bricks are fed into an HPT300 multi-cylinder hydraulic cone crusher for secondary medium crushing. The discharge opening is adjusted to 20mm, yielding medium crushed material of 20-50mm. The matching motor power is 220kW. After medium crushing, the used ladle magnesia-carbon bricks are fed into an ø800×1000 double-roll crusher for tertiary fine crushing. The roller spacing is adjusted to 5mm, yielding fine crushed material with a particle size distribution of 0-5mm. The matching motor power is 2×45kW. Closed-circuit screening is performed using a vibrating screen with a 5mm screen aperture. The material on the screen is returned to the crusher's feed hopper for further crushing, ultimately yielding qualified undersize magnesia-carbon bricks with a particle size of 0-5mm for use in steel ladles.

[0039] 3) Hydration and drying Crushed material of the required particle size is fed into an integrated hydration and drying equipment. This equipment is a fully enclosed horizontal cylindrical structure with a heated lifting device on the central horizontal axis. Steam is first introduced into the equipment, and the internal lifting device agitates the material, allowing it to fully hydrate for 18 minutes in a 130°C steam environment, hydrolyzing compounds such as aluminum nitride and aluminum carbide. Excess steam is condensed and recycled. Subsequently, a vacuum environment is created by drawing a vacuum inside the equipment, which then heats the lifting device. The hydrated material is then heated to 65°C and dried for 12 minutes in this vacuum environment, controlling the moisture content to ≤0.5%, resulting in dried material. Dust generated during the drying process is carried by the airflow into a dust collection system for collection and recovery. The total residence time of the material within the equipment is 30 minutes.

[0040] 4) Roller The dried material is fed into a double-roller mill for compaction via a quantitative feeder. The double-roller mill applies a pressure of 20 MPa to the material, with the mill disc rotation speed set to 20 rpm. The material is subjected to crushing, shearing, and friction between the mill discs and the rollers. Based on the strength difference between true and false particles, the false particles are selectively crushed, while the true particles remain intact, resulting in a material free of false particles.

[0041] 5) Grading and screening The de-fake granular material is fed into a three-layer vibrating screen for grading and screening. The screen aperture sizes are 5mm for the upper layer, 3mm for the middle layer, and 1mm for the lower layer. The frequency is 30Hz under no-load conditions to prevent screen damage, 50Hz during feeding to ensure screen penetration, and 70Hz to enhance screen cleaning when material blockage occurs, with an amplitude of 3mm. The screen is supported by elastic vibrating strips (hard rubber) to reduce impact on the screen. Material exceeding 5mm is returned to the feed hopper of the roller mill for circulating roller milling. Aggregates of 0-1mm, 1-3mm, and 3-5mm particle sizes are stored in their respective finished product hoppers.

[0042] The recycled magnesia-carbon bricks made from the above aggregates have a bulk density of 3.11 g / cm³. 3 The apparent porosity is 3.2%, the room temperature pressure resistance is 78.7 MPa, and the number of water cooling cycles at 1100℃ is 20, all of which meet the usage requirements.

[0043] Example 2:

[0044] This embodiment is basically the same as Embodiment 1, except that the processing object is different and the process parameters are optimized and adjusted. This embodiment uses recycled aluminum-carbon bricks from the three main casting components as raw material, and the process parameters are adjusted as follows: Crushing parameters: The roller spacing of the fine crushing section double roll crusher is adjusted to 8mm to facilitate the production of large-diameter aggregates.

[0045] Hydration and drying parameters: The water vapor temperature in the integrated hydration and drying equipment is 140℃, the hydration time is 20min, the drying temperature is 70℃, and the drying time is 10min, which facilitates the full hydration and drying of the aluminum-carbon bricks after use.

[0046] Roller parameters: The roller pressure is adjusted to 25MPa to further improve the removal of false particles.

[0047] Screening parameters: A four-layer vibrating screen is used, with screen aperture sizes of 8mm for the upper layer, 5mm and 3mm for the middle layer, and 1mm for the lower layer. The feeding frequency is 50Hz to ensure the screening rate.

[0048] The recycled alumina-carbon bricks made from the above aggregates have a bulk density of 3.19 g / cm³. 3 The apparent porosity is 5.1%, the compressive strength is 120.7 MPa, and the number of water cooling cycles at 1100℃ is 32, all of which meet the usage requirements.

[0049] In the above embodiments, the entire process equipment operates under a fully enclosed negative pressure system, which ensures smooth material flow, reduces the risk of material blockage, and prevents dust leakage, making it environmentally friendly and free from secondary pollution. The recycled material prepared using this process and equipment not only has stable product quality but also meets the requirements for bulk density, mechanical strength, and thermal shock stability, making it a high-quality refractory raw material.

[0050] The above description is merely a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations that are directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A comprehensive treatment process for the resource utilization of used refractory materials, characterized in that, This includes the following steps connected sequentially via a conveying device: 1) Pretreatment: After the used refractory materials are pretreated by sorting and surface cleaning to remove impurities, the used refractory materials are recycled. 2) Three-stage crushing and closed-circuit screening: The pre-treated refractory raw materials are subjected to primary coarse crushing, secondary medium crushing and tertiary fine crushing in sequence, and closed-circuit screening is performed after fine crushing. Unqualified materials after screening are returned to the crushing feed silo for recycling crushing, and qualified materials enter the next process to obtain crushed materials of the target particle size. 3) Hydration and drying: Materials of qualified particle size are fed into an integrated hydration and drying equipment. After the materials are fully hydrated and dried, dried materials are obtained. The material entering the hydration and drying integrated equipment is first fully hydrated in a steam environment at 120-140℃ to hydrolyze compounds such as aluminum nitride and aluminum carbide in the material; then it is heated to 55-75℃ in a vacuum environment for drying to obtain dried material with a moisture content of ≤0.5%. The total residence time of the material in the hydration and drying integrated equipment is 20-30 minutes. 4) Roller mill: The dried material is fed into the roller mill through a quantitative feeder unit for crushing and selectively crushing false particles to obtain material with de-false particles; 5) Grading and screening: The de-fake granular material is fed into a multi-layer vibrating screen for grading and screening to obtain recycled refractory materials of different particle sizes. The material on the screen is returned to the roller mill for recycling.

2. The comprehensive treatment process for the resource utilization of used refractory materials according to claim 1, characterized in that, The primary coarse crushing uses a jaw crusher to crush the pre-treated material to 50-80mm using the compression principle; the secondary medium crushing uses a jaw crusher or cone crusher to crush the material to 20-50mm; the tertiary fine crushing uses a double roll crusher or impact crusher to refine the material to the target particle size, and the screen aperture size of the matching closed-circuit screen is consistent with the required maximum particle size.

3. The comprehensive treatment process for the resource utilization of used refractory materials according to claim 1, characterized in that, In step 4), the roller mill uses a hydraulic pressurization system to apply a pressure of 15-25 MPa to the material.

4. The comprehensive treatment process for the resource utilization of used refractory materials according to claim 1, characterized in that, The integrated hydration and drying equipment is a stacked disc vacuum dryer.

5. The comprehensive treatment process for the resource utilization of used refractory materials according to claim 1, characterized in that, The vibration frequency of each section of the vibrating screen is 25~35Hz when unloaded, 45~55Hz when feeding, and increases to 65~75Hz when blocked.

6. The comprehensive treatment process for the resource utilization of used refractory materials according to claim 1, characterized in that, The quantitative feeder unit consists of a manual gate valve, a screw conveyor, and a weighing system. The manual gate valve is used to adjust the feed rate to the screw conveyor, and the weighing system is used to weigh the material conveyed from the screw conveyor to the roller mill, thereby adjusting the feed rate of the roller mill.

7. The comprehensive treatment process for the resource utilization of used refractory materials according to claim 1, characterized in that, The used refractory material is an oxide-carbon composite refractory material salvaged from the lining of an industrial kiln.

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