Refractory brick and preparation method thereof

Abstract

The invention discloses a method for preparing refractory bricks from carbon fibers recovered from a carbon-carbon composite material quitting service in a photovoltaic thermal field, and relates to the technical field of refractory materials. According to the method, carbon fibers in the carbon-carbon composite material of the photovoltaic thermal field are subjected to cleaning, drying, length control and other treatments, and then refractory raw materials such as kaolin, magnesium oxide and aluminum oxide and binding agents and additives such as phenolic resin are prepared according to a specific proportion. Then, dry-mixing the powder and the carbon fibers, wet-mixing the granules and the binding agent by a horizontal mixer, and finally mixing by a double-shaft paddle mixer to ensure that the materials are uniform; afterwards, a brick press and a steel mold are used for compression molding, drying is conducted through a drying kiln, firing is conducted through an electric furnace, precise temperature and time control is conducted in all stages, and finally polishing finishing and quality detection are conducted. The prepared refractory brick is excellent in performance, has good high temperature resistance, erosion resistance and thermal shock resistance, opens up a new way for reutilization of photovoltaic thermal field wastes, and has remarkable economic and environmental benefits.

Description

[0001] The present application is a divisional application of the application filed on February 21, 2025, with the application number 202510194042.1, and the invention name of a method for preparing refractory bricks from carbon fibers recycled from carbon-carbon composite materials retired from service in photovoltaic thermal fields. TECHNICAL FIELD

[0002] The present application relates to the technical field of refractory materials, in particular to a method for preparing refractory bricks from carbon fibers recycled from carbon-carbon composite materials retired from service in photovoltaic thermal fields. BACKGROUND

[0003] With the rapid development of the photovoltaic industry, carbon-carbon composites in photovoltaic thermal fields are retired from service in large quantities after a certain period of service. If these discarded carbon-carbon composites are directly discarded, not only a large amount of land resources will be occupied, but also potential pollution to the environment will be caused by the difficult-to-degrade components such as carbon fibers contained therein. At the same time, as the key material for the inner lining of kilns in high-temperature industrial fields such as steel, ceramics, glass manufacturing, etc., the market demand for refractory bricks continues to rise, and the performance requirements are increasingly stringent, and the traditional refractory brick preparation raw materials are facing the dilemma of resource shortage and cost increase. Under this background, how to realize the resource utilization of waste in photovoltaic thermal fields and improve the performance of refractory bricks has become a problem to be solved.

[0004] Therefore, it is of great significance to develop a method for preparing refractory bricks from carbon fibers recycled from carbon-carbon composite materials retired from service in photovoltaic thermal fields, in order to improve resource utilization and reduce production costs. SUMMARY

[0005] In view of the above technical problems, the present application solves the problem of preparing refractory bricks with excellent performance by recycling and pretreating carbon fibers in carbon-carbon composite materials and mixing them with refractory raw materials, and then forming, drying, and firing.

[0006] In order to achieve the above purpose, the technical solution adopted by the present application is as follows: a method for preparing refractory bricks from carbon fibers recycled from carbon-carbon composite materials retired from service in photovoltaic thermal fields, comprising the following steps: Step 1: Prepare raw materials, carbon fibers, refractory raw materials, binders, and additives.

[0007] Step 2: First, dry mix the refractory raw materials and carbon fibers, then wet mix the binder and granular material, and finally mix the dry mixed and wet mixed materials together.

[0008] Step 3: Use a brick press and a steel mold to press the green brick.

[0009] Step 4: Dry using a drying kiln or drying chamber.

[0010] Step five: using high-temperature equipment such as electric furnace, gas furnace, etc. for firing.

[0011] Step six: using grinding machine, grinding wheel and other tools to polish and trim the refractory bricks.

[0012] Preferably, the carbon fibers in step one are derived from photovoltaic thermal field out-of-service carbon-carbon composite materials and are pretreated by washing and drying.

[0013] Preferably, the addition amount of carbon fibers in step one accounts for 0.2%-10% of the total amount of refractory raw materials.

[0014] Preferably, the refractory raw materials in step one include kaolin, silica, alumina, etc., and the particle size of the powder is not greater than 0.2mm, and the particle size of the granular material is 0.3-5mm.

[0015] Preferably, the dry mixing time in step two is 10-30 minutes, the wet mixing time is 10-30 minutes, and the final mixing time is 20-30 minutes.

[0016] Preferably, the pressing pressure in step three is 50-300MPa, and the pressure holding time is 5-15 seconds.

[0017] Preferably, the drying temperature in step four is 120-180℃, and the drying time is 20-40 hours.

[0018] Preferably, in step five, first, normal temperature firing is used for 2-5 hours, then high-temperature firing is used for 30-35 hours, and finally, it is slowly reduced to room temperature.

[0019] The technical scheme provided in the application has the following beneficial effects compared with the prior art: 1. The application innovatively recycles the carbon fibers in the photovoltaic thermal field out-of-service carbon-carbon composite materials, turning waste into treasure, effectively reducing the pollution of waste to the environment, reducing the dependence on traditional refractory raw materials, relieving the resource pressure, and fitting the current sustainable development environmental protection concept.

[0020] 2. The application adjusts the refractory raw materials such as kaolin, magnesium oxide, alumina, etc. reasonably, and fires in a high-temperature electric furnace through a strict temperature rising and holding procedure, so that the refractory bricks can stably serve in a high-temperature environment, meeting the high-temperature industrial demand such as steel smelting.

[0021] 3. The silicon carbide component forms an oxidation-resistant whisker at high temperature, and combined with the alkaline anti-erosion environment provided by the magnesium oxide and other raw materials, it can effectively resist the erosion of slag, molten liquid, etc. on the refractory bricks, prolong the service life of the kiln lining, and reduce the industrial production cost.

[0022] 4. The carbon fibers of the present application are uniformly distributed in the brick body, and can buffer thermal stress and prevent the refractory brick from cracking and peeling under frequent temperature shock conditions, thereby ensuring the continuous and stable operation of the kiln.

[0023] 5. The present application ensures that each refractory brick has uniform and consistent physical and chemical properties through precise screening of raw materials, multi-step fine operation of mixing ingredients, strict process parameter control in each link of forming, drying and firing, and polishing and finishing and overall quality detection in post-processing, thereby providing reliable protection for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The process flowchart of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art without creative labor based on the embodiments in the present application are within the scope of protection of the present application.

[0027] The carbon fibers are disassembled and collected from the carbon-carbon composite material that has exited service in the photovoltaic thermal field. These carbon fibers may have silicides, carbides and other impurities attached to the surface during service in the photovoltaic thermal field, as well as dust and other pollutants, and need to be cleaned. A suitable chemical cleaning agent, such as a weak alkaline solution, is used to soak the carbon fibers under mild stirring conditions, the soaking time is controlled to be 30-60 minutes, then the carbon fibers are rinsed with clean water to neutral, and then placed in a drying oven to dry at a temperature of 80-120℃ for 2-4 hours to remove surface moisture.

[0028] According to the performance requirements of the specific refractory brick, the length of the carbon fibers is precisely controlled to be between 3-50mm using cutting equipment, for example, for refractory bricks that require higher toughness, the fiber length of 10-30mm is preferred. The addition amount of carbon fibers is determined according to the end use and performance requirements of the refractory brick, and is generally between 0.2%-10% of the total amount of refractory raw materials. If the refractory brick is prepared for use in a high-temperature and frequently heated impact environment, the preferred addition amount of carbon fibers is 2%-5%.

[0029] The refractory raw materials can be selected from kaolin, silica, alumina, etc. The particle size of the powder is not greater than 0.2 mm, preferably not greater than 0.12 mm; the particle size of the granular material is 0.3-5 mm, preferably 1-1.2 mm. The ratio is determined according to the specific formula requirements, and the magnesium oxide and / or aluminum oxide accounts for 70%-90%, the silicon carbide accounts for 1%-4%, the graphite accounts for 0.5%-10%, and the aluminum accounts for 0.3%-1%.

[0030] The binder is selected from phenolic resin, pitch, etc., and the additives such as plasticizer, water reducing agent, etc. When the binder is phenolic resin, it needs to be adjusted according to its viscosity and curing characteristics. For different seasons or environmental temperatures, a suitable amount of solvent can be added for dilution to ensure its proper fluidity. The addition amount is generally between 1%-8% of the total amount of refractory raw materials. As for the additives, the plasticizer is added in an appropriate amount according to the plasticity of the raw materials. If it is found that the mixture is too dry and hard to shape, the plasticizer can be added in a proportion of 0.1%-0.5% to improve the processing performance of the material. The water reducing agent is used to reduce the water consumption and avoid cracking due to excessive moisture during drying of the brick body. The general addition amount is 0.2%-0.8%.

[0031] When mixing the raw materials, first dry mix the refractory raw materials with the carbon fibers, then wet mix the binder with the granular material, and finally mix the dry mixed and wet mixed materials together.

[0032] Dry mixing, the powder and refractory fibers are mixed without adding liquid. The powder and refractory fibers are initially uniformly dispersed, allowing them to contact and combine more fully with other materials in subsequent mixing, laying the foundation for the stability of the final refractory brick performance. In this application, the powder such as kaolin, silica, alumina, etc. and carbon fibers are evenly distributed to avoid local overabundance or shortage of carbon fibers.

[0033] In specific operation, high-efficiency mixing machines such as horizontal mixers, double-shaft paddle mixers, etc. are used, and the mixing time is generally 10-30 minutes.

[0034] Wet mixing, the granular material and the binder are mixed. Through the action of the binder, the granular material can be better bonded together to form a material with certain viscosity and plasticity for subsequent forming operation. In this application, the binder such as phenolic resin, pitch, etc. can effectively combine the granular material with a particle size of 0.3-5 mm, giving the material certain shape retention ability.

[0035] In specific operation, high-efficiency mixing machines are also used, and the mixing time is usually 10-30 minutes.

[0036] Final mixing, the dry mixing and wet mixing of the material is mixed again. To ensure that the mixture of the various ingredients to achieve a high degree of uniform dispersion, eliminate the possible existence of agglomeration or local component segregation phenomenon, so that the performance of the refractory brick is more uniform and stable. In this application, after dry mixing and wet mixing of the material, although the respective internal to a certain degree of uniformity, but the two materials need to be further mixed uniformly to ensure the quality of the final product.

[0037] Specific operation, using a mixer for 20-30 minutes to ensure uniform distribution of various ingredients.

[0038] Using a brick press and steel mold to press the green brick. The final mixing of the material is evenly filled into the steel mold, and the brick press is used for pressing forming. The forming pressure is accurately controlled between 50-300 MPa according to the specific formula and the size of the green brick, for example, for the refractory brick with high density requirement, the forming pressure is close to 300 MPa. The holding time is generally 5-15 seconds, and the pressure sensor is used to monitor the pressure change in real time during the holding process to ensure stable pressure and dense green brick. After forming, the green brick is removed from the mold through the demolding device, and immediately subjected to green brick processing to remove defects such as burrs and flying needles, making the green brick regular in appearance.

[0039] Dry operation is carried out in a drying kiln or drying chamber, and an air curtain is set at the entrance of the drying kiln to prevent external cold air from directly entering the kiln. According to the size and moisture content of the green brick, the drying temperature is generally between 120-180℃, and the drying time is generally between 20-40 hours. Temperature and humidity sensors are installed at different positions in the drying kiln to monitor temperature and humidity changes in real time. Control the drying temperature and humidity to avoid cracking or deformation of the green brick.

[0040] During firing, an electric furnace is selected as the firing equipment, and the heating elements, insulation materials, etc. of the electric furnace are checked before use to ensure normal operation of the equipment. The dried green brick is neatly placed in the electric furnace hearth, and the temperature rising program is set. From room temperature to 150-185℃ at a rate of ≤20℃ / min, this stage is mainly to remove the residual water and a small amount of volatile matter in the green brick. During the temperature rising process, a gas analyzer is used to monitor the change of gas composition in the furnace to ensure the smooth discharge of volatile matter. After reaching the set temperature, it is kept for 2-5 hours to make the internal structure of the green brick stable.

[0041] Then increase the temperature to 1550-1700℃ at a rate of ≤80℃ / min, and closely monitor the shrinkage of the green brick during this rapid temperature rising process. If abnormal shrinkage is found, adjust the temperature rising rate in time. After reaching the high temperature interval, keep the temperature between 1550-1700℃ for 30-35 hours, which is the key firing stage, making the raw materials fully react to form stable ceramic phase and crystal structure, and improving the performance of the refractory brick.

[0042] After the firing is completed, the furnace is slowly cooled to room temperature at a rate of ≤350℃ / min, and the combination of air cooling and natural cooling of the furnace body is used. In the initial stage of cooling, the air cooling intensity is appropriately increased, and as the temperature decreases, the air cooling is gradually reduced. The cooling rate is precisely adjusted using a temperature controller to avoid cracks in the brick due to rapid cooling and to ensure the quality of the refractory bricks.

[0043] After production, the surface of the refractory brick is polished using a grinding machine. According to the purpose and precision requirements of the brick, the appropriate grit size of the grinding wheel is selected, such as 80-120 mesh for refractory bricks with high surface flatness requirements. During polishing, the feed speed of the grinding machine is controlled at 5-10mm / min to ensure a smooth surface and remove surface hard shell, protrusions and other defects generated during the firing process. At the same time, the edges of the brick are trimmed using the grinding wheel to make them sharp and accurate in size.

[0044] Quality detection is also required. First, visual and measuring methods are used to check the surface flatness, color uniformity, and size deviation of the refractory brick. The surface flatness error is controlled within ±0.5mm, and the size deviation meets the corresponding national standards. Then, physical property testing is performed. The compressive strength of the refractory brick is measured using a universal material testing machine, and the compressive strength is not less than the design standard value. The thermal expansion coefficient is measured using a thermal dilatometer to determine the dimensional stability at high temperatures. The thermal conductivity is measured using a thermal conductivity tester to ensure that it meets the use requirements. Only refractory bricks that meet all the testing requirements can enter the market.

[0045] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A firebrick, characterized by, The carbon fiber, the refractory raw material and the binder; The adding amount of the carbon fiber is 0.2-10% of the total amount of the refractory raw material, and the adding amount of the binder is 1-8% of the total amount of the refractory raw material; The refractory raw material is powder and / or granular material, the particle size of the powder is not more than 0.2mm, and the particle size of the granular material is 0.3-5mm; The carbon fiber is derived from photovoltaic thermal field out of service carbon / carbon composite material and is pretreated by cleaning and drying.

2. The firebrick according to claim 1, characterized in that The adding amount of the carbon fiber is 2-5% of the total amount of the refractory raw material; The length of the carbon fiber is 3-50mm.

3. The firebrick according to claim 1, characterized in that The refractory raw material comprises one or more of kaolin, silica and alumina.

4. The firebrick according to claim 1, wherein The refractory raw material is composed of 70-90% of magnesium oxide and / or alumina, 1-4% of silicon carbide, 0.5-10% of graphite and 0.3-1% of aluminum in terms of mass percentage.

5. The firebrick according to claim 1, wherein The binder comprises one or more of phenolic resin and pitch.

6. The firebrick according to any one of claims 1 to 5, characterized in that The additive comprises one or more of plasticizer and water reducing agent; The adding amount of the plasticizer is 0.1-0.5% of the total amount of the carbon fiber, the refractory raw material and the binder; The adding amount of the water reducing agent is 0.2-0.8% of the total amount of the carbon fiber, the refractory raw material and the binder.

7. A method of producing the refractory brick according to any one of claims 1 to 6, characterized by, The method comprises the following steps: (1) dry mixing the powder of the refractory raw material with the carbon fiber to obtain dry mixed material, wet mixing the granular material of the refractory raw material with the binder to obtain wet mixed material, and then finally mixing the dry mixed material and the wet mixed material; (2) using a brick press and a steel mold to press the green brick; (3) drying in a drying kiln or drying chamber; (4) using high-temperature equipment for firing; (5) polishing and trimming the refractory brick.

8. The method of producing a refractory brick according to claim 7, characterized by, The mixing time of the dry mixing is 10-30 minutes; The mixing time of the wet mixing is 10-30 minutes; The mixing time of the final mixing is 20-30 minutes.

9. The method of producing a refractory brick according to claim 7, characterized by, The forming pressure of the pressing is 50-300MPa, and the pressure holding time is 5-15 seconds; The drying temperature is 120-180℃, and the time is 20-40 hours; The feed speed of the grinding machine is controlled to be 5-10mm / min during polishing.

10. The method of producing a refractory brick according to claim 7, characterized by, The firing is performed by increasing the temperature from room temperature to 150-185℃ at a rate of ≤20℃ / min, and then holding for 2-5 hours; Then increasing the temperature to 1550-1700℃ at a rate of ≤80℃ / min, and then holding for 30-35 hours; After the firing is completed, the furnace is slowly cooled to room temperature at a rate of ≤350℃ / min, and the cooling is performed by combining air cooling with natural cooling of the furnace body.

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