Synthetic mica composite refractory precast brick for muffle furnace and preparation method thereof

Abstract

The application provides a high-temperature-resistant and erosion-resistant refractory precast block, which comprises a working surface and a backing surface; the working surface is formed by small-size crystal grains and unique dendritic eutectic structures of white corundum, zirconia or synthetic zircon corundum under high-temperature conditions, so that the erosion resistance is realized; a bridging agent A is added into the raw material of the working surface, and a bridging agent B is added into the raw material of the backing surface; the working surface and the backing surface form an integrated structure through the action of the bridging agent A and the bridging agent B, so that the falling of the working surface is avoided, the pollution to the product is avoided, the impurities in the artificial synthetic mica are further reduced, and the yield of the product is improved.

Description

Technical Field

[0001] This invention relates to a material for a synthetic mica furnace, specifically to a composite refractory precast brick for a synthetic mica furnace and its preparation method, belonging to the technical field of synthetic mica production equipment. Background Technology

[0002] Mica possesses excellent elasticity, transparency, high-frequency insulation, and chemical stability, making it widely used in aerospace, electrical appliances, paints, cosmetics, and other fields. Currently, high-quality natural mica resources are mainly concentrated in a few countries such as India, Canada, and Brazil, while my country's high-quality natural mica resources are relatively scarce. Therefore, synthetic mica has emerged, also known as fluorophlogopite (KMg3(AlSi3O4)). 10 F2), is a typical layered silicate. It is made from natural mica (general formula X). 0.5-1 Y 2-3 Z 10 OH in (OH)2 - Using F - As an alternative, this synthetic mica can withstand temperatures above 1200℃, has a higher resistivity (approximately 1000 times higher) than natural mica, is more resistant to acids and alkalis, is peelable, transparent, and elastic. Therefore, synthetic mica has a wider range of applications.

[0003] The main processes for synthesizing mica include the internal heating method and the crucible lowering seed crystal method. The crucible lowering seed crystal method uses a platinum crucible for melting, which is costly and not suitable for large-scale production. The internal heating method uses a refractory lining as the furnace wall, places the raw materials in a certain proportion in the furnace, and melts the materials by electrode heating. After cooling, the synthetic mica product is obtained. Although the internal heating method can produce mica products on a large scale, the refractory lining is severely corroded during the melting process due to the presence of fluorides, potassium, and sodium in the synthetic mica product. The lining material adheres to the mica product, is extremely difficult to remove, and causes a certain degree of contamination to the mica product.

[0004] In existing technologies, the production of synthetic mica typically employs an integrated furnace (melting furnace). The refractory bricks used for the lining of the furnace in the synthetic mica production process are essentially disposable products, requiring replacement with new lining material for each batch, resulting in significant waste and environmental pollution. Furthermore, the integrated furnace structure makes product separation difficult and leads to problems such as furnace buildup and product contamination. CN111829344A proposes a prefabricated brick structure to facilitate the assembly and disassembly of the furnace during the synthetic mica production process, but issues such as furnace buildup, corrosion, and product contamination still exist. CN 218380427 U discloses an electrically heated melting and homogenizing furnace with a double-layer refractory lining; however, when used for synthetic mica production, its high-temperature resistance and corrosion resistance are poor, and the double-layer structure also presents technical challenges related to detachment. To address the separation problem of synthetic mica products, CN109813113A discloses a circulating kiln for synthetic mica production, i.e., a mica production method. This method involves an inert barrier layer on the inner surface of a cylindrical furnace body. The inert barrier layer is made of a metallic element or alloy with a melting point greater than 1750℃. However, the inert barrier layer is made of a completely different material from the kiln lining. During the kiln cooling process, the thermal expansion coefficients of the inert barrier layer and the kiln lining are completely different, resulting in a technical problem of separation between the two layers. CN116144204A discloses a separation coating for a synthetic mica smelting furnace. The separation coating is applied to the refractory bricks of the synthetic mica smelting furnace. A layer of separation coating is applied to the working surface of the refractory bricks, relying on the excellent resistance of the separation coating to mica solution erosion. Then, utilizing the difference in thermal expansion coefficients between the separation coating and the refractory bricks, the synthetic mica melt automatically separates from the refractory bricks after cooling. In other words, after separation, the separation coating and the synthetic mica become integrated and detach from the refractory bricks together, posing a technical problem of contaminating the synthetic mica product.

[0005] Existing technologies for synthesizing mica using furnaces and kilns suffer from difficulties in product separation and easy detachment of the isolation layer. Furthermore, the furnace lining material contaminates the synthesized mica product. Since synthetic mica requires extremely stringent control of impurities (within a range of less than one-thousandth), contaminated mica must be discarded, leading to a reduced product yield. In conclusion, the refractory lining material of smelting furnaces has severely hampered the technological development of the synthetic mica industry. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention proposes a high-temperature resistant and corrosion-resistant refractory precast block. This refractory precast block includes a working surface and a backing surface. The working surface utilizes small-sized grains and a unique dendritic eutectic structure formed by white corundum, zirconium oxide, or synthetic zirconium corundum under high-temperature conditions to achieve corrosion resistance. A bridging agent A is added to the raw material of the working surface, and a bridging agent B is added to the raw material of the backing surface. Through the action of bridging agents A and B, the working surface and the backing surface form a complete integrated structure, thereby preventing the working surface from detaching and thus avoiding product contamination. This further reduces impurities in synthetic mica and improves product yield.

[0007] According to a first embodiment of the present invention, a composite refractory precast brick for a synthetic mica furnace is provided.

[0008] A composite refractory precast brick for a synthetic mica furnace, comprising a working surface and a backing surface. The working surface is composed of one or more of zirconium corundum powder, white corundum powder, and alumina powder, along with a thickener and bridging agent A. The backing surface is composed of fused alumina powder and / or high-alumina bauxite powder as aggregates, and one or more of white corundum powder, calcium aluminate cement, fused alumina powder, and alumina powder, along with additives and bridging agent B, as fine powder.

[0009] Wherein: bridging agent A is one or more of sodium carbonate, sodium silicate, potassium carbonate, and potassium silicate; bridging agent B is sodium disilicate and / or phosphorus pentoxide.

[0010] Preferably, bridging agent A is sodium silicate and bridging agent B is phosphorus pentoxide.

[0011] In this invention, the amount of bridging agent A in the working surface raw material is 0.01-1 wt%, preferably 0.05-0.8 wt%, more preferably 0.1-0.5 wt%, and even more preferably 0.15-0.4 wt%. For example: 0.1 wt%, 0.12 wt%, 0.15 wt%, 0.18 wt%, 0.2 wt%, 0.22 wt%, 0.25 wt%, 0.26 wt%, 0.28 wt%, 0.3 wt%, 0.32 wt%, 0.35 wt%, 0.38 wt%, 0.4 wt%, 0.42 wt%, 0.45 wt%, 0.48 wt%, 0.5 wt%.

[0012] In this invention, the amount of bridging agent B in the backing material is 0.01-1 wt% of the total amount of other backing materials, preferably 0.05-0.8 wt%, more preferably 0.1-0.5 wt%, and even more preferably 0.15-0.4 wt%. For example: 0.1 wt%, 0.12 wt%, 0.15 wt%, 0.18 wt%, 0.2 wt%, 0.22 wt%, 0.25 wt%, 0.26 wt%, 0.28 wt%, 0.3 wt%, 0.32 wt%, 0.35 wt%, 0.38 wt%, 0.4 wt%, 0.42 wt%, 0.45 wt%, 0.48 wt%, 0.5 wt%.

[0013] As a preferred option, the raw material composition of the working face is as follows: The zirconium corundum powder is 70-90 parts by weight, preferably 72-88 parts by weight, and more preferably 74-86 parts by weight; for example: 70 parts by weight, 72 parts by weight, 74 parts by weight, 75 parts by weight, 76 parts by weight, 78 parts by weight, 80 parts by weight, 81 parts by weight, 82 parts by weight, 83 parts by weight, 85 parts by weight, 86 parts by weight, 88 parts by weight, and 90 parts by weight.

[0014] 2-30 parts by weight of white fused alumina powder, preferably 4-25 parts by weight, more preferably 6-20 parts by weight; for example: 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, 10 parts by weight, 10.2 parts by weight, 10.5 parts by weight, 10.6 parts by weight, 10.8 parts by weight, 11 parts by weight, 11.5 parts by weight, 12 parts by weight, 12.5 parts by weight, 13 parts by weight, 13.5 parts by weight, 14 parts by weight, 14.5 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight.

[0015] The alumina powder is 2-30 parts by weight, preferably 4-25 parts by weight, and more preferably 6-20 parts by weight; for example: 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, 10 parts by weight, 10.2 parts by weight, 10.5 parts by weight, 10.6 parts by weight, 10.8 parts by weight, 11 parts by weight, 11.5 parts by weight, 12 parts by weight, 12.5 parts by weight, 13 parts by weight, 13.5 parts by weight, 14 parts by weight, 14.5 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, and 20 parts by weight.

[0016] Thickener: 0.1-2 parts by weight, preferably 0.15-1.5 parts by weight, more preferably 0.2-1 parts by weight; for example: 0.1 parts by weight, 0.15 parts by weight, 0.16 parts by weight, 0.18 parts by weight, 0.2 parts by weight, 0.22 parts by weight, 0.25 parts by weight, 0.28 parts by weight, 0.3 parts by weight, 0.32 parts by weight, 0.35 parts by weight, 0.38 parts by weight, 0.4 parts by weight, 0.42 parts by weight, 0.45 parts by weight, 0.48 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1.0 parts by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight.

[0017] Bridging agent A is used in amounts of 0.01-1 parts by weight, preferably 0.05-0.8 parts by weight, more preferably 0.1-0.5 parts by weight; for example: 0.01 parts by weight, 0.05 parts by weight, 0.08 parts by weight, 0.1 parts by weight, 0.12 parts by weight, 0.15 parts by weight, 0.18 parts by weight, 0.2 parts by weight, 0.22 parts by weight, 0.25 parts by weight, 0.28 parts by weight, 0.3 parts by weight, 0.32 parts by weight, 0.35 parts by weight, 0.38 parts by weight, 0.4 parts by weight, 0.45 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, and 1.0 parts by weight.

[0018] Preferably, the raw materials for the backing surface include aggregate raw materials and fine powder raw materials.

[0019] Wherein: the raw material usage of aggregate is 50-90% of the total raw material usage of the backing surface, preferably 55-85%, more preferably 60-80%; and even more preferably 65-75%. For example, 60%, 62%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 82%, 85%, 88%, 90%.

[0020] Preferably, the raw materials for the aggregate are composed entirely of high-alumina bauxite powder, or entirely of coke powder, or a mixture of high-alumina bauxite powder and coke powder in any proportion. For example: the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:0.1 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:0.2 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:0.3 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:0.4 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:0.5 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:0.6 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:0.7 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:0.8 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:0.9 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:1 ratio; the raw materials for aggregates consist of high-alumina bauxite powder and coke powder in a 1:1.1 ratio; the raw materials for aggregates consist of high-alumina bauxite powder in a 1:1.2 ratio. The raw materials for the aggregate are composed of high-alumina bauxite powder and charred gemstone powder in a 1:1.3 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:1.5 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:1.8 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:2 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:3 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:4 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:5 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:6 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:7 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:8 ratio; high-alumina bauxite powder and charred gemstone powder in a 1:9 ratio; and high-alumina bauxite powder and charred gemstone powder in a 1:10 ratio.

[0021] Preferably, the raw material composition of the fine powder is as follows: The white fused alumina powder is 2-25 parts by weight, preferably 4-20 parts by weight, and more preferably 6-15 parts by weight; for example: 2 parts by weight, 4 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.2 parts by weight, 9.5 parts by weight, 9.8 parts by weight, 10 parts by weight, 10.2 parts by weight, 10.5 parts by weight, 10.6 parts by weight, 10.8 parts by weight, 11 parts by weight, 11.2 parts by weight, 11.5 parts by weight, 11.8 parts by weight, 12 parts by weight, 12.5 parts by weight, 13 parts by weight, 13.5 parts by weight, 14 parts by weight, 14.5 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, and 20 parts by weight.

[0022] The amount of charred gemstone powder is 5-25 parts by weight, preferably 7-20 parts by weight, and more preferably 10-15 parts by weight; for example: 2 parts by weight, 4 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.2 parts by weight, 9.5 parts by weight, 9.8 parts by weight, 10 parts by weight, 10.2 parts by weight, 10.5 parts by weight, 10.6 parts by weight, 10.8 parts by weight, 11 parts by weight, 11.2 parts by weight, 11.5 parts by weight, 11.8 parts by weight, 12 parts by weight, 12.2 parts by weight, 12.5 parts by weight, 12.8 parts by weight, 13 parts by weight, 13.5 parts by weight, 14 parts by weight, 14.5 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, and 20 parts by weight.

[0023] The alumina powder is 1-10 parts by weight, preferably 2-9 parts by weight, and more preferably 3-8 parts by weight; for example: 2 parts by weight, 3 parts by weight, 4 parts by weight, 4.2 parts by weight, 4.5 parts by weight, 4.8 parts by weight, 5 parts by weight, 5.2 parts by weight, 5.5 parts by weight, 5.8 parts by weight, 6 parts by weight, 6.2 parts by weight, 6.5 parts by weight, 6.8 parts by weight, 7 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.2 parts by weight, 9.5 parts by weight, 9.8 parts by weight, and 10 parts by weight.

[0024] The amount of calcium aluminate cement is 1-10 parts by weight, preferably 2-9 parts by weight, and more preferably 3-8 parts by weight; for example: 2 parts by weight, 3 parts by weight, 4 parts by weight, 4.2 parts by weight, 4.5 parts by weight, 4.8 parts by weight, 5 parts by weight, 5.2 parts by weight, 5.5 parts by weight, 5.8 parts by weight, 6 parts by weight, 6.2 parts by weight, 6.5 parts by weight, 6.8 parts by weight, 7 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.2 parts by weight, 9.5 parts by weight, 9.8 parts by weight, and 10 parts by weight.

[0025] The additive is 0.5-10 parts by weight, preferably 1-8 parts by weight, more preferably 2-5 parts by weight; 1 part by weight, 1.2 parts by weight, 1.5 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.5 parts by weight, 2.8 parts by weight, 3 parts by weight, 3.2 parts by weight, 3.5 parts by weight, 3.8 parts by weight, 4 parts by weight, 4.2 parts by weight, 4.5 parts by weight, 4.8 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, and 8 parts by weight.

[0026] Bridging agent B is present in amounts of 0.01-1 parts by weight, preferably 0.05-0.8 parts by weight, more preferably 0.1-0.5 parts by weight; for example: 0.01 parts by weight, 0.05 parts by weight, 0.08 parts by weight, 0.1 parts by weight, 0.12 parts by weight, 0.15 parts by weight, 0.18 parts by weight, 0.2 parts by weight, 0.22 parts by weight, 0.25 parts by weight, 0.28 parts by weight, 0.3 parts by weight, 0.32 parts by weight, 0.35 parts by weight, 0.38 parts by weight, 0.4 parts by weight, 0.45 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, and 1.0 parts by weight.

[0027] In this invention, the zirconium corundum powder has a particle size of ≤0.076mm, an Al2O3 content of ≥65%, a ZrO2 content of ≥20%, and a SiO2 content of ≤15%.

[0028] In this invention, the white corundum powder has a particle size of ≤0.076mm and an Al2O3 content of ≥99%.

[0029] In this invention, the alumina powder contains Al2O3 ≥ 99% and has a particle size of 0.5-10 μm.

[0030] In this invention, the high-alumina bauxite contains ≥65% Al2O3.

[0031] In this invention, the charred gemstone powder contains 30-50% Al2O3 and ≤2% Fe2O3.

[0032] In this invention, the thickener is hydroxymethyl cellulose or polyacrylamide.

[0033] In this invention, the additive is one or more of silica fume, sodium tripolyphosphate, or sodium hexametaphosphate.

[0034] Preferably, the sintered gemstone powder in the backing aggregate raw material is composed of sintered gemstone powder with various particle sizes.

[0035] Preferably, the high-alumina bauxite powder in the backing aggregate raw material is composed of high-alumina bauxite powder with various particle sizes.

[0036] Preferably, the backing aggregate raw materials include raw materials with particle sizes of 0.5-1mm, 1-2mm, 2-3mm, and 3-5mm; preferably, the proportion of raw materials with a particle size of 0.5-1mm is 20-30%, the proportion of raw materials with a particle size of 1-2mm is 15-25%, the proportion of raw materials with a particle size of 2-3mm is 15-25%, and the proportion of raw materials with a particle size of 3-5mm is 20-30%.

[0037] Preferably, the calcium aluminate cement is pure calcium aluminate cement, with Al2O3 72-82% and CaO 19-23%.

[0038] Preferably, the alumina powder is active alumina powder.

[0039] In this invention, the thickness of the working surface is 5-50 mm, preferably 8-30 mm, and more preferably 10-20 mm.

[0040] In this invention, the thickness of the backing surface is 100-500mm, preferably 150-400mm, and more preferably 200-300mm.

[0041] According to a second embodiment of the present invention, a method for preparing composite refractory precast bricks for synthetic mica furnaces or a method for preparing composite refractory precast bricks for synthetic mica furnaces as described in the first embodiment is provided.

[0042] A method for preparing composite refractory precast bricks for synthetic mica furnaces, the method comprising the following steps: (1) Preparation of backing surface mud: Add the backing surface fine powder raw materials in proportion and mix evenly to obtain matrix fine powder; then mix the backing surface aggregate evenly, add the matrix fine powder, and then add 1-10% water to mix and obtain backing surface mud. (2) Preparation of working face mud: Add the working face raw materials according to the proportion, mix evenly, add 15-25% water, and continue stirring to obtain working face mud; (3) Preparation of composite refractory prefabricated bricks for artificial mica furnace: First, pour the backing clay into the mold and vibrate to form it. After the backing clay is leveled, pour the working clay into the mold and vibrate to form it. After leveling and solidification, the composite refractory prefabricated bricks for artificial mica furnace are obtained.

[0043] In this invention, the stirring and mixing are carried out using a mixer.

[0044] In this invention, the material of the mold is not limited and can be any of wood, iron, steel, alloy, etc. The shape of the mold is not limited, and the mold interface can be any of square, rectangle, arc, circle, sector, wedge, triangle, rhombus, etc.

[0045] In this invention, the vibration is performed using a vibratory machine or a vibratory rod.

[0046] In this invention, the curing includes drying, baking, calcination, or sintering.

[0047] In existing technologies, the manufacture of synthetic mica utilizes furnaces (or kilns), which presents technical problems such as raw material corrosion of the furnace lining (or inner lining), lining material entering the product, furnace lining detachment, and delamination of the furnace lining. This invention provides an integrated composite refractory precast brick for synthetic mica furnaces. The composite refractory precast brick provided by this invention has an integral structure, including a working surface and a backing surface. When a furnace using this composite refractory precast brick is used for synthetic mica production, the working surface and backing surface remain an integral structure, without separation or detachment. Therefore, the problem of furnace lining material entering the product is eliminated. The working surface achieves corrosion resistance through small-sized grains and a unique dendritic eutectic structure formed under high-temperature conditions using white corundum, zirconium oxide, or synthetic zirconium corundum.

[0048] In this invention, the working surface is made of one or more of zirconium corundum powder, white corundum powder, and alumina powder, along with thickener and bridging agent A. The resulting working surface is resistant to high temperatures and corrosion, avoiding or reducing the corrosion of the working surface by artificially synthesized mica raw materials, and also preventing the components of the working surface from entering the product.

[0049] In this invention, the backing material is used to provide support. It uses high-temperature resistant and heat-insulating slag powder and / or high-alumina bauxite powder as aggregates, and one or more of white corundum powder, calcium aluminate cement, slag powder and alumina powder, along with additives and bridging agent B, as fine powders.

[0050] In this invention, bridging agent A is added to the working surface material, and bridging agent B is added to the backing surface material. Bridging agent A is one or more of sodium carbonate, sodium silicate, potassium carbonate, and potassium silicate; bridging agent B is sodium disilicate and / or phosphorus pentoxide. Both bridging agent A and bridging agent B are raw materials that react at relatively low temperatures to form a glassy phase. Bridging agent A forms a glassy phase in the working surface, forming an integral structure with other raw materials, while also acting as a connecting framework. Bridging agent B forms a glassy phase in the backing surface, forming an integral structure with other raw materials, while also acting as a connecting framework. At the interface between the working surface and the backing surface, bridging agent A and bridging agent B react to form a stable structure; simultaneously, the products of bridging agent A and bridging agent B respectively form an integral structure with the working surface through bridging agent A, and with the backing surface through bridging agent B; thus connecting and fixing the working surface and the backing surface, thereby preventing separation between the working surface and the backing surface and ensuring the integrated structure of the entire precast brick. Furthermore, when the prepared composite refractory precast bricks are used in a furnace for the production of artificially synthesized mica, at around 1000℃, bridging agents A and B undergo a chemical reaction to generate a low-melting-point phase, which remains stable. During use, this low-melting-point phase generates a liquid phase in the matrix, thereby eliminating thermal stress and expansion stress, and further preventing the separation of the working surface and the backing surface.

[0051] In this invention, the composite refractory precast bricks prepared by bridging agent A and bridging agent B are integrated structures. When the furnace prepared by this composite refractory precast brick is used for the production of artificial mica, there is no separation or detachment of the entire composite refractory precast brick.

[0052] In this invention, the inventors discovered through experiments that adding bridging agent A to the working surface material and bridging agent B to the backing surface material can effectively connect the working surface and the backing surface, resulting in a unified structure for both.

[0053] Furthermore, the inventors discovered through experiments that the amounts of bridging agents A and B also affect the bonding strength between the working surface and the backing surface. Insufficient amounts of bridging agents A and B result in weak bonding strength. Excessive amounts of bridging agents A and B lead to an excessive amount of reaction products at the interface between the working and backing surfaces, also affecting the bonding strength. Simultaneously, the amounts of bridging agents A and B also affect the overall compressive strength of the precast brick. Appropriate amounts of bridging agents A and B act as an adhesive, which helps improve the compressive strength of the precast brick; however, excessive amounts of bridging agents A and B can negatively impact the adhesion between other components in the working and backing surfaces, thus affecting the compressive strength. Therefore, by reasonably controlling the amount of bridging agent A and bridging agent B, the performance of the precast bricks can be further improved, and the performance of the furnace made from the composite refractory precast bricks can be further guaranteed.

[0054] As a preferred method, to balance the bonding strength and compressive strength of the working surface and backing surface of the composite refractory precast brick, the amount of bridging agent A is selected as 0.01-1 wt% of the total amount of other raw materials on the working surface, preferably 0.05-0.8 wt%, more preferably 0.1-0.5 wt%; the amount of bridging agent B is selected as 0.01-1 wt% of the total amount of other raw materials on the backing surface, preferably 0.05-0.8 wt%, more preferably 0.1-0.5 wt%. This ensures both the bonding strength of the working surface and backing surface of the composite refractory precast brick and the compressive strength of the entire composite refractory precast brick meets the requirements for manufacturing an artificial mica furnace, thereby ensuring the reusability of the entire furnace and improving its service life.

[0055] In this invention, the raw materials used in the working surface are all high-temperature resistant and corrosion-resistant inorganic materials, and the thickener acts as a binder to thicken the raw materials. Zirconium corundum powder, white corundum powder, and alumina powder are all commercially available products.

[0056] In this invention, the raw materials used in the working surface are all inorganic materials with good high-temperature resistance and thermal insulation properties. Additives are used as binders to bind the raw materials together. White corundum powder, fused alumina powder, alumina powder, and calcium aluminate cement are all commercially available products.

[0057] As a preferred option, in order to improve the strength of the backing surface, raw materials with different particle sizes are selected and combined in the aggregate raw materials of the backing surface to ensure the strength of the backing surface.

[0058] In this invention, the thickness of the working surface and the thickness of the backing surface are not limited. Generally, the thickness of the working surface is 5-50 mm, and the thickness of the backing surface is 100-500 mm.

[0059] In this invention, the composite refractory precast bricks are made from specific raw materials and in specific quantities. The preparation method is relatively conventional, and the composite refractory precast bricks can be obtained through ordinary mixing, drying and firing.

[0060] In this invention, the mixing time is generally 3-30 minutes, preferably 5-20 minutes. Drying can be carried out by air drying or by using a dryer at 30-100°C, and the calcination temperature is generally 600-1500°C.

[0061] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects: 1. This invention utilizes the characteristics of two different refractory materials, the backing surface and the working surface, to enable the precast blocks for synthetic mica furnaces to have slight or no corrosion from mica products and heat insulation properties, thus solving the problem of adhesion between synthetic mica furnace products and clay bricks. 2. In order to solve the stress cracking between the two-layer interface, the present invention introduces bridging agent A and bridging agent B into the two layers of material respectively. Bridging agent A and bridging agent B play the role of connecting and fixing the working surface and the backing surface; at the same time, bridging agent A and bridging agent B play the role of skeleton and connection in the whole precast brick.

[0062] 3. The composite refractory precast brick prepared by this invention has an integrated structure, which reduces the erosion of the refractory lining material by synthetic mica and avoids the problem of mica products being contaminated after the refractory lining material is eroded during the smelting process. 4. The composite refractory precast bricks prepared by this invention have the function of being reused, thus avoiding waste of resources. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the structure of a composite refractory precast brick for an artificially synthesized mica furnace according to the present invention. Detailed Implementation

[0064] The technical solution of the present invention will be illustrated below with examples. The scope of protection sought by the present invention includes, but is not limited to, the following embodiments.

[0065] A composite refractory precast brick for a synthetic mica furnace, comprising a working surface and a backing surface; characterized in that: the raw material of the working surface is composed of one or more of zirconium corundum powder, white corundum powder, and alumina powder, along with a thickener and a bridging agent A; the raw material of the backing surface is composed of fused alumina powder and / or high-alumina bauxite powder as aggregate, and one or more of white corundum powder, calcium aluminate cement, fused alumina powder, and alumina powder, along with additives and a bridging agent B, as fine powder. Wherein: bridging agent A is one or more of sodium carbonate, sodium silicate, potassium carbonate, and potassium silicate; bridging agent B is sodium disilicate and / or phosphorus pentoxide.

[0066] Preferably, the amount of bridging agent A in the working face raw material is 0.01-1 wt% of the total amount of other raw materials in the working face, preferably 0.05-0.8 wt%, and more preferably 0.1-0.5 wt%.

[0067] Preferably, the amount of bridging agent B in the backing material is 0.01-1 wt% of the total amount of other backing materials, preferably 0.05-0.8 wt%, and more preferably 0.1-0.5 wt%.

[0068] Preparation process: A method for synthesizing composite refractory precast bricks for mica furnaces, the method comprising the following steps: (1) Preparation of backing surface mud: Add the backing surface fine powder raw material in proportion, stir for 15 min, mix evenly to obtain matrix fine powder; then stir the backing surface aggregate for 5 min to mix evenly, add matrix fine powder, then add 5% water (based on the weight of powder raw material), stir for 10 min to mix, and obtain backing surface mud. (2) Preparation of working face mud: Add the working face raw materials according to the proportion, stir for 20 minutes, mix evenly, add 18% water (based on the weight of the powder raw materials), and continue stirring for 10 minutes to obtain the working face mud; (3) Preparation of composite refractory prefabricated bricks for artificially synthesized mica furnace: First, pour the backing clay into the mold and vibrate it to form the shape. After the backing clay is leveled, pour the working clay into the mold and vibrate it to form the shape. After leveling, dry it at room temperature for 2 hours, and then calcine it at 900℃ for 12 hours. After cooling, the composite refractory prefabricated bricks for artificially synthesized mica furnace are obtained.

[0069] The working surface of the composite refractory precast brick has a thickness of 10mm, and the backing surface has a thickness of 230mm.

[0070] Using the above-described preparation process, the composition and dosage of raw materials for preparing refractory precast bricks were adjusted, and the following experiments were conducted: Example 1

[0071] Composition of working face mud material: 8 kg of zirconium corundum fine powder, 1 kg of white corundum fine powder, 1 kg of alumina micro powder, 0.05 kg of hydroxymethyl cellulose, and 0.02 kg of Na2SiO3. Composition of backing clay material: Matrix composition: 1.0 kg white fused alumina fine powder, 1.2 kg fused alumina fine powder, 0.5 kg activated alumina powder, 0.5 kg pure calcium aluminate cement, 0.3 kg silica fume, 0.02 kg P2O5.

[0072] Aggregates: 2 kg of high-alumina bauxite clinker (5-3 mm), 1.5 kg of coke alumina (3-2 mm), 1.5 kg of coke alumina (2-1 mm), and 2 kg of coke alumina (1-0.5 mm). Example 2

[0073] Composition of working face mud material: 8 kg of zirconium corundum fine powder, 1 kg of white corundum fine powder, 1 kg of alumina micro powder, 0.03 kg of polyacrylamide, and 0.02 kg of sodium carbonate; Composition of backing clay material: Matrix subdivision: 1.0Kg white fused alumina fine powder, 1.2Kg fused alumina fine powder, 0.5Kg activated alumina powder, 0.5Kg pure calcium aluminate cement, 0.3Kg sodium tripolyphosphate, 0.02Kg sodium disilicate.

[0074] Aggregate: 2 kg of charred gemstones (5-3 mm), 1.5 kg of charred gemstones (3-2 mm), 1.5 kg of charred gemstones (2-1 mm), and 2 kg of charred gemstones (1-0.5 mm). Example 3

[0075] Composition of working face mud material: 8 kg of zirconium corundum fine powder, 1 kg of white corundum fine powder, 1 kg of alumina micro powder, 0.03 kg of polyacrylamide, and 0.02 kg of sodium silicate; Composition of backing clay material: Matrix subdivision: 1.0Kg white fused alumina fine powder, 1.2Kg fused alumina fine powder, 0.5Kg activated alumina powder, 0.5Kg pure calcium aluminate cement, 0.3Kg sodium hexametaphosphate, and 0.02Kg sodium disilicate.

[0076] Aggregates: 2 kg of high-alumina bauxite clinker (5-3 mm), 1.5 kg of high-alumina bauxite clinker (3-2 mm), 1.5 kg of high-alumina bauxite clinker (2-1 mm), and 2 kg of high-alumina bauxite clinker (1-0.5 mm). Example 4

[0077] Repeat Example 1, except that bridging agent A is sodium carbonate. Example 5

[0078] Repeat Example 1, except that bridging agent A is potassium carbonate. Example 6

[0079] Repeat Example 1, except that bridging agent A is potassium silicate. Example 7

[0080] Example 1 was repeated, except that the amount of Na2SiO3 and P2O5 added was 0.0005 kg. Example 8

[0081] Repeat Example 1, except that the amount of Na2SiO3 and P2O5 added is 0.005Kg. Example 9

[0082] Repeat Example 1, except that the amount of Na2SiO3 and P2O5 added is 0.1Kg each. Example 10

[0083] Repeat Example 1, except that the amount of Na2SiO3 and P2O5 added is 0.5Kg each.

[0084] Comparative Example 1 Composition of working face mud material: 8 kg of zirconium corundum fine powder, 1 kg of white corundum fine powder, 1 kg of alumina micro powder, and 0.05 kg of hydroxymethyl cellulose; Composition of backing clay material: Matrix subdivision: 1.0 kg of white fused alumina fine powder, 1.2 kg of charred alumina fine powder, 0.5 kg of activated alumina powder, 0.5 kg of pure calcium aluminate cement, and 0.3 kg of silica fume.

[0085] Aggregates: 2 kg of high-alumina bauxite clinker (5-3 mm), 1.5 kg of coke alumina (3-2 mm), 1.5 kg of coke alumina (2-1 mm), and 2 kg of coke alumina (1-0.5 mm).

[0086] The refractory precast bricks prepared in Examples 1-10 and Comparative Example 1 were cut into 160mm long * 40mm wide * 40mm thick (including a 10mm working surface and a 30mm backing surface) samples using a dedicated brick cutter. The adhesion between the working surface and the backing surface was tested using the national standard GB / T3001-2017, "Refractory Materials - Test Method for Flexural Strength at Room Temperature," and the compressive strength of the samples was tested using the national standard GB / T5072-2008, "Refractory Materials - Test Method for Compressive Strength at Room Temperature." The test results are shown in the table below:

[0087] The refractory precast bricks prepared in Examples 1 to 10 were used to build furnaces with a diameter of 2.5 to 3.4 meters (variable diameter); these furnaces were used to produce synthetic mica. The impurity content of the synthetic mica products obtained by the spectral analysis method (GB / T 21114) was less than 1‰. Among them, the impurity content of the synthetic mica products produced by the furnaces made with the refractory precast bricks prepared in Example 1 was only 0.03%.

[0088] In the raw materials used in this invention embodiment, the inorganic raw materials only need to meet the requirements for particle size and composition. Specifically: Zirconium corundum fine powder: particle size ≤0.076mm, Al2O3 content 68%, ZrO2 content 26%, SiO2 content 5%. White corundum fine powder: particle size ≤0.076mm, Al2O3 content 99.5%. Alumina micro powder (activated alumina powder): Al2O3 content 99.8%, particle size 0.5-10μm. Calcite fine powder: Al2O3 content 44%, Fe2O3 content 1.2%. Pure calcium aluminate cement: Al2O3 content 78%. High-alumina bauxite clinker: Al2O3 content 68%, 5-3mm. All inorganic materials are commercially available products.

[0089] Hydroxymethyl cellulose (419273) manufactured by Merck & Co., Germany, with an average molecular weight (Mw) of 90,000. Polyacrylamide (749222) manufactured by Merck & Co., Germany, with an average molecular weight (Mn) of 150,000. Sodium tripolyphosphate (238503) manufactured by Merck & Co., Germany, with an analytical weight of 36,786. Sodium hexametaphosphate (71600) manufactured by Merck & Co., Germany, with a concentration of 65-70% P₂O₅.

Claims

1. A composite refractory precast brick for a synthetic mica furnace, the composite refractory precast brick comprising a working surface and a backing surface; characterized in that: The working surface material consists of zirconium corundum powder, white corundum powder, alumina powder, thickener, and bridging agent A; the backing surface material uses charred alumina powder and / or high-alumina bauxite powder as aggregates, and white corundum powder, calcium aluminate cement, charred alumina powder, alumina powder, additives, and bridging agent B as fine powders. Wherein: bridging agent A is one or more of sodium carbonate, sodium silicate, potassium carbonate, and potassium silicate; bridging agent B is sodium disilicate and / or phosphorus pentoxide; and the additive is one or more of silica fume, sodium tripolyphosphate, or sodium hexametaphosphate.

2. The composite refractory precast brick for synthetic mica furnaces according to claim 1, characterized in that: In the raw materials of the working face, the amount of bridging agent A is 0.01-1 wt% of the total amount of other raw materials in the working face; In the backing material, the amount of bridging agent B is 0.01-1 wt% of the total amount of other backing materials.

3. The composite refractory precast brick for synthetic mica furnaces according to claim 2, characterized in that: In the raw materials of the working face, the amount of bridging agent A is 0.05-0.8 wt% of the total amount of other raw materials in the working face; In the backing material, the amount of bridging agent B is 0.05-0.8 wt% of the total amount of other backing materials.

4. The composite refractory precast brick for synthetic mica furnaces according to claim 3, characterized in that: In the raw materials of the working face, the amount of bridging agent A is 0.1-0.5 wt% of the total amount of other raw materials in the working face; In the backing material, the amount of bridging agent B is 0.1-0.5 wt% of the total amount of other backing materials.

5. The composite refractory precast brick for synthetic mica furnaces according to claim 1, characterized in that: The raw material composition of the working face is as follows: 70-90 parts by weight of zirconium corundum powder; 2-30 parts by weight of white corundum powder; 2-30 parts by weight of alumina powder; Thickener 0.1-2 parts by weight; Bridging agent A: 0.01-1 parts by weight.

6. The composite refractory precast brick for synthetic mica furnaces according to claim 5, characterized in that: The raw material composition of the working face is as follows: 72-88 parts by weight of zirconium corundum powder; 4-25 parts by weight of white corundum powder; 4-25 parts by weight of alumina powder; Thickener 0.15-1.5 parts by weight; Bridging agent A: 0.05-0.8 parts by weight.

7. The composite refractory precast brick for synthetic mica furnaces according to claim 6, characterized in that: The raw material composition of the working face is as follows: 74-86 parts by weight of zirconium corundum powder; 6-20 parts by weight of white fused alumina powder; 6-20 parts by weight of alumina powder; Thickener 0.2-1 parts by weight; Bridging agent A: 0.1-0.5 parts by weight.

8. The composite refractory precast brick for synthetic mica furnaces according to claim 1, characterized in that: The raw materials for the backing surface include aggregate raw materials and fine powder raw materials; Among them, the raw material usage of aggregate is 50-90% of the total raw material usage of the backing surface; The raw material composition of the fine powder is as follows: 2-25 parts by weight of white corundum powder; 5-25 parts by weight of charred gemstone powder; 1-10 parts by weight of alumina powder; 1-10 parts by weight of calcium aluminate cement; Additives: 0.5-10 parts by weight; Bridging agent B 0.01-1 parts by weight.

9. The composite refractory precast brick for synthetic mica furnaces according to claim 8, characterized in that: The amount of aggregate used is 55-85% of the total amount of raw materials used in the backing surface; The raw material composition of the fine powder is as follows: 4-20 parts by weight of white corundum powder; 7-20 parts by weight of charred gemstone powder; 2-9 parts by weight of alumina powder; 2-9 parts by weight of calcium aluminate cement; Additives 1-8 parts by weight; Bridging agent B: 0.05-0.8 parts by weight.

10. The composite refractory precast brick for synthetic mica furnaces according to claim 9, characterized in that: The amount of aggregate used is 60-80% of the total amount of raw materials used in the backing surface; The raw material composition of the fine powder is as follows: 6-15 parts by weight of white corundum powder; 10-15 parts by weight of charred gemstone powder; 3-8 parts by weight of alumina powder; 3-8 parts by weight of calcium aluminate cement; 2-5 parts by weight of additives; Bridging agent B: 0.1-0.5 parts by weight.

11. The composite refractory precast brick for synthetic mica furnaces according to claim 1, characterized in that: The zirconium corundum powder has a particle size of ≤0.076mm, an Al2O3 content of ≥65%, a ZrO2 content of ≥20%, and a SiO2 content of ≤15%. The white fused alumina powder has a particle size of ≤0.076mm and an Al2O3 content of ≥99%. The alumina powder contains Al2O3 ≥ 99% and has a particle size of 0.5-10 μm; The high-alumina bauxite contains ≥65% Al2O3; The charred gemstone powder contains 30-50% Al2O3 and ≤2% Fe2O3.

12. The composite refractory precast brick for synthetic mica furnaces according to claim 1, characterized in that: The thickener is hydroxymethyl cellulose or polyacrylamide.

13. The composite refractory precast brick for synthetic mica furnaces according to claim 1, characterized in that: The backing aggregate raw materials include coke powder of various particle sizes; and / or, high-alumina bauxite powder of various particle sizes.

14. The composite refractory precast brick for synthetic mica furnaces according to claim 13, characterized in that: The backing aggregate raw materials include raw materials with particle sizes of 0.5-1mm, 1-2mm, 2-3mm, and 3-5mm.

15. The composite refractory precast brick for synthetic mica furnaces according to claim 14, characterized in that: The proportion of raw materials with a particle size of 0.5-1mm is 20-30%, the proportion of raw materials with a particle size of 1-2mm is 15-25%, the proportion of raw materials with a particle size of 2-3mm is 15-25%, and the proportion of raw materials with a particle size of 3-5mm is 20-30%.

16. The composite refractory precast brick for synthetic mica furnaces according to claim 1, characterized in that: The calcium aluminate cement is pure calcium aluminate cement, with Al2O3 72-82% and CaO 19-23%; and / or The alumina powder is active alumina powder.

17. The composite refractory precast brick for synthetic mica furnaces according to any one of claims 1-16, characterized in that: The thickness of the working surface is 5-50 mm; and / or The thickness of the backing surface is 100-500mm.

18. The composite refractory precast brick for synthetic mica furnaces according to claim 17, characterized in that: The thickness of the working surface is 8-30 mm; and / or The thickness of the backing surface is 150-400mm.

19. A method for preparing composite refractory precast bricks for synthetic mica furnaces according to any one of claims 1-18, the method comprising the following steps: (1) Preparation of backing surface mud: Add the backing surface fine powder raw materials in proportion and mix evenly to obtain matrix fine powder; then mix the backing surface aggregate evenly, add the matrix fine powder, and then add 1-10% water to mix and obtain backing surface mud. (2) Preparation of working face mud: Add the working face raw materials according to the proportion, mix evenly, add 15-25% water, and continue stirring to obtain working face mud; (3) Preparation of composite refractory prefabricated bricks for artificial mica furnace: First, pour the backing clay into the mold and vibrate to form it. After the backing clay is leveled, pour the working clay into the mold and vibrate to form it. After leveling and solidification, the composite refractory prefabricated bricks for artificial mica furnace are obtained.

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