Low thermal conductivity tin bath bottom brick and preparation method thereof

Abstract

The present invention belongs to the technical field of refractory material preparation, and specifically relates to a low thermal conductivity tin bath bottom brick and a preparation method thereof. The method comprises the following steps: (1) preparing a blank: mixing a synthetic material, microporous mullite aggregate, pure calcium aluminate cement, and high-temperature cement completely, pouring the mixture into a mold, and forming the blank through high-frequency vibration to obtain a blank; (2) sintering; (3) polishing: after cutting and polishing, a low thermal conductivity tin bath bottom brick is obtained. The preparation method of the synthetic material is as follows: crushing and mixing plate-shaped corundum, pure calcium aluminate cement, plate-shaped clay, clay, and food-grade cyclodextrin, adding water and extruding the mixture at 60-75MPa, naturally drying in the shade for 1-2 days, then drying at 50-110°C, entering a high-temperature shuttle kiln for sintering, and after sintering, crushing the mixture to obtain the synthetic material. The low thermal conductivity tin bath bottom brick of the present invention has low thermal conductivity, long service life, and good H2 diffusion resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory material preparation, and particularly relates to a low-thermal-conductivity tin bath bottom brick and a preparation method thereof. Background Art

[0002] The tin bath is a critical thermal engineering device in the float glass production process. The float glass forming process proceeds as follows: the batch material is melted into molten glass in a furnace and then fed into the tin bath. The glass is then spread thinly on the molten tin surface and thinned by a stretching machine until it reaches the desired thickness. After cooling and shaping, it leaves the bath. The majority of the world's flat glass is produced using the float process. When the float glass process first emerged, the bath bottom was flat, with a uniform depth. As the process evolved and to conserve molten tin and facilitate operation, it evolved into a stepped design. The typical bath bottom consists of a steel shell lined with refractory mortar, refractory concrete, or refractory bricks, with a depth of 40-100mm. Cracking and floating defects in the bath bottom bricks are a significant challenge to address, so the tin bath bottom bricks must be secured with fasteners and adhere to strict construction specifications. Generally, graphite strips are inlaid on the walls of the tank in the high-temperature zone to prevent the glass liquid from adhering to the tank walls. There is also a practice of laying graphite bricks or ramming carbon materials on the bottom of the tank in the high-temperature zone. In order to adjust the heat dissipation of the tank bottom, some cooling pipes are arranged at appropriate positions on the bottom of the tank.

[0003] However, with the continuous development of high-end glass technology, the temperature of molten glass has continued to rise from the original 1400°C to the current production requirement of 1550°C. The molten glass flowing into the tin bath carries a higher temperature. The original tin bath bottom bricks are no longer suitable for the heat resistance and energy saving requirements of high-end glass production. Therefore, the tin bath bottom bricks are required to have not only resistance to tin penetration and nepheline petrification, low permeability, and stable hydrogen diffusion rate, but also higher temperature resistance requirements. The thermal conductivity of the commonly used tin bath bottom bricks is generally high, resulting in high energy consumption and low thermal efficiency during the use of the tin bath. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention aims to provide a low thermal conductivity tin bath bottom brick with low thermal conductivity, long service life and good H2 diffusion resistance.

[0005] The invention also provides a preparation method thereof, which is simple, feasible and suitable for large-scale production.

[0006] The low thermal conductivity tin bath bottom brick of the present invention comprises the following raw materials in parts by mass:

[0007]

[0008] The synthetic material comprises the following raw materials in parts by mass:

[0009]

[0010]

[0011] The synthetic material is prepared by grinding and mixing plate-shaped corundum, pure calcium aluminate cement, plate-shaped clay, clay, and food-grade cyclodextrin, adding water, and extruding at 60-75 MPa. The mixture is then naturally shade-dried for 1-2 days, then oven-dried at 50-110°C, sintered in a high-temperature shuttle kiln, and crushed after sintering to obtain the synthetic material. The synthetic material has a particle size of 3-6 mm.

[0012] The microporous mullite aggregate has a particle size of 2-5 mm.

[0013] The preparation method of the microporous mullite aggregate comprises the following steps: grinding alumina and quartz sand to a size below 100 mesh and drying to remove moisture, wherein the alumina is an industrial alumina raw material with a mass ratio of more than 98%, and the SiO2 in the quartz sand is greater than 99%; mixing the alumina and quartz sand in a mass ratio of 3:1, first adding the alumina and then adding the quartz sand to obtain a mixed mullite raw material; dividing the mullite raw material into four equal portions, and feeding the mixed material into an electric furnace for melting at 2000±100°C, 200V voltage, and 1800±200A current for 60 minutes; blowing air upward from a bottom blowpipe to form pores, wherein the air flow rate in the blowpipe is 6mL / min and the bubble size is 0.5-1mm; simultaneously, stirring is started at a rotation speed of 2000r / min; after 5 minutes, the temperature is rapidly lowered to room temperature within 10 minutes, and the particles are crushed to 2-5mm in size to obtain the microporous mullite aggregate.

[0014] The drying time is 68-76 hours.

[0015] The sintering steps are: continuously heating to 350°C within 46-50 hours, continuously heating to 850°C within 70-74 hours, continuously heating to 1100°C within 70-74 hours, continuously heating to 1500°C within 70-74 hours, continuously heating to 1650°C within 96-120 hours, maintaining at 1650°C for 10-14 hours, continuously cooling to 1500°C within 92-100 hours, continuously cooling to 1350°C within 70-74 hours, continuously cooling to 1100°C within 70-74 hours, continuously cooling to 750°C within 70-74 hours, continuously cooling to 250°C within 70-74 hours, continuously cooling to 110°C within 20-28 hours, and continuously cooling to room temperature within 20-28 hours.

[0016] The Al2O3 content of the high-temperature cement is 68-77 wt.%, preferably CA70 produced by Henan Li Te Refractory Materials Co., Ltd.

[0017] The pure calcium aluminate cement comprises the following chemical components: Al2O3 80-85%, CaO 10-15%, Fe2O3 0.1%, and SiO2 3-7%.

[0018] The plate-like clay comprises the following chemical components: Al2O3 42-48%, SiO2 38-48%, Fe2O 3≤ 0.5%, TiO 2≤ 0.5%, K2O ≤ 1.5%, Na2O ≤ 0.5%; particle size is 1-3mm.

[0019] The clay powder includes the following chemical components: Al2O3 32-45%, SiO2 48-51%, Fe2O 3≤ 1.5%, TiO 2≤ 0.5%, K2O ≤ 0.5%, Na2O ≤ 0.5%; particle size less than 1mm.

[0020] The method for preparing the low thermal conductivity tin bath bottom brick of the present invention comprises the following steps:

[0021] (1) Preparation of green body: The synthetic material, microporous mullite aggregate, pure calcium aluminate cement and high temperature cement are completely mixed and poured into a mold, and then formed by high-frequency vibration to obtain a green body;

[0022] (2) sintering;

[0023] (3) Grinding: After cutting and grinding, the low thermal conductivity tin bath bottom brick is obtained.

[0024] The sintering is carried out in a high-temperature shuttle kiln at 1500-1550° C. for 36-48 hours.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention prefabricates the synthetic material in advance and adds microporous mullite aggregate to the synthetic material, thereby reducing the volume density of the brick body and increasing the porosity from the perspective of physical properties. The microporous mullite aggregate has closed pores, which further increases the closed porosity. At the same time, the particle size of the synthetic material is increased to 3-6 mm, thereby increasing the open porosity. The purpose of thermal insulation and energy saving is achieved while maintaining a balance between open / closed porosity, ensuring that the hydrogen diffusion index is reduced to below 50. DETAILED DESCRIPTION

[0027] The present invention is further described below with reference to the following examples, but the protection scope of the present invention is not limited thereto.

[0028] Unless otherwise specified, all raw materials used in the examples are commercially available.

[0029] Preparation method of microporous mullite aggregate:

[0030] Alumina and quartz sand are respectively ground to less than 100 mesh and dried to be free of moisture, wherein the alumina is an industrial alumina raw material with a content of more than 98%, and the SiO2 in the quartz sand is greater than 99%; the materials are mixed according to a mass ratio of alumina to quartz sand of 3:1, and the alumina is first added, and then the quartz sand is added to obtain a mixed mullite raw material; the mullite raw material is evenly divided into 4 times and put into an electric furnace for melting at 2000±100°C, 200V voltage, and 1800±200A current for 60 minutes; air is blown upward from the bottom blowpipe to form holes, the air flow rate in the blowpipe is 6mL / min, and the bubble size is 0.5-1mm; stirring is started at the same time, the rotation speed is 2000r / min, and after 5 minutes, the temperature is rapidly cooled to room temperature within 10 minutes, and the particles are crushed to 2-5mm to obtain microporous mullite aggregate.

[0031] Example 1

[0032] The low thermal conductivity tin bath bottom brick comprises the following raw materials in parts by mass:

[0033]

[0034] The synthetic material comprises the following raw materials in parts by mass:

[0035]

[0036] The preparation method of the synthetic material comprises the following steps: grinding and mixing plate-shaped corundum, pure calcium aluminate cement, plate-shaped clay, clay and food-grade cyclodextrin, adding water and extruding the mixture at 68 MPa, naturally drying the mixture in the shade for 2 days, drying the mixture at 110° C. for 72 hours, sintering the mixture in a high-temperature shuttle kiln, and crushing the mixture after sintering to obtain the synthetic material.

[0037] The sintering steps are: continuously heating to 350°C within 48 hours, continuously heating to 850°C within 72 hours, continuously heating to 1100°C within 72 hours, continuously heating to 1500°C within 72 hours, continuously heating to 1650°C within 96 hours, maintaining at 1650°C for 12 hours, continuously cooling to 1500°C within 96 hours, continuously cooling to 1350°C within 72 hours, continuously cooling to 1100°C within 72 hours, continuously cooling to 750°C within 72 hours, continuously cooling to 250°C within 72 hours, continuously cooling to 110°C within 24 hours, and continuously cooling to room temperature within 24 hours.

[0038] The high temperature cement is CA70 produced by Henan Li Te Refractory Material Co., Ltd., and its Al2O3 content is 68-77wt.%.

[0039] The pure calcium aluminate cement includes the following chemical components: Al2O3 80%, CaO 15%, Fe2O3 0.1%, and SiO2 4%.

[0040] The plate-like clay comprises the following chemical components: Al2O3 42-48%, SiO2 38-48%, Fe2O 3≤ 0.5%, TiO 2≤ 0.5%, K2O ≤ 1.5%, Na2O ≤ 0.5%; particle size is 1-3mm.

[0041] The clay powder includes the following chemical components: Al2O3 32-45%, SiO2 48-51%, Fe2O 3≤ 1.5%, TiO 2≤ 0.5%, K2O ≤ 0.5%, Na2O ≤ 0.5%; particle size less than 1mm.

[0042] The method for preparing the low thermal conductivity tin bath bottom brick comprises the following steps:

[0043] (1) Preparation of green body: The synthetic material, microporous mullite aggregate, pure calcium aluminate cement and high temperature cement are completely mixed and poured into a mold, and then formed by high-frequency vibration to obtain a green body;

[0044] (2) Sintering: sintering in a high temperature shuttle kiln at 1500-1550℃ for 42h;

[0045] (3) Grinding: After cutting and grinding, the low thermal conductivity tin bath bottom brick is obtained.

[0046] Example 2

[0047] The low thermal conductivity tin bath bottom brick comprises the following raw materials in parts by mass:

[0048]

[0049] The synthetic material comprises the following raw materials in parts by mass:

[0050]

[0051]

[0052] The preparation method of the synthetic material comprises the following steps: grinding and mixing plate-shaped corundum, pure calcium aluminate cement, plate-shaped clay, clay and food-grade cyclodextrin, adding water and extruding the mixture at 75 MPa, naturally drying the mixture in the shade for 2 days, drying the mixture at 50° C. for 76 hours, sintering the mixture in a high-temperature shuttle kiln, and crushing the mixture after sintering to obtain the synthetic material.

[0053] The sintering steps are: continuously heating to 350°C within 50 hours, continuously heating to 850°C within 74 hours, continuously heating to 1100°C within 74 hours, continuously heating to 1500°C within 74 hours, continuously heating to 1650°C within 120 hours, maintaining at 1650°C for 14 hours, continuously cooling to 1500°C within 100 hours, continuously cooling to 1350°C within 74 hours, continuously cooling to 1100°C within 74 hours, continuously cooling to 750°C within 74 hours, continuously cooling to 250°C within 74 hours, continuously cooling to 110°C within 28 hours, and continuously cooling to room temperature within 28 hours.

[0054] The high temperature cement is CA70 produced by Henan Li Te Refractory Material Co., Ltd., and its Al2O3 content is 68-77wt.%.

[0055] The pure calcium aluminate cement includes the following chemical components: Al2O3 80%, CaO 15%, Fe2O3 0.1%, and SiO2 4%.

[0056] The plate-like clay comprises the following chemical components: Al2O3 42-48%, SiO2 38-48%, Fe2O 3≤ 0.5%, TiO 2≤ 0.5%, K2O ≤ 1.5%, Na2O ≤ 0.5%; particle size is 1-3mm.

[0057] The clay powder includes the following chemical components: Al2O3 32-45%, SiO2 48-51%, Fe2O 3≤ 1.5%, TiO 2≤ 0.5%, K2O ≤ 0.5%, Na2O ≤ 0.5%; particle size less than 1mm.

[0058] The method for preparing the low thermal conductivity tin bath bottom brick comprises the following steps:

[0059] (1) Preparation of green body: The synthetic material, microporous mullite aggregate, pure calcium aluminate cement and high temperature cement are completely mixed and poured into a mold, and then formed by high-frequency vibration to obtain a green body;

[0060] (2) Sintering: sintering in a high temperature shuttle kiln at 1500-1550℃ for 48h;

[0061] (3) Grinding: After cutting and grinding, the low thermal conductivity tin bath bottom brick is obtained.

[0062] Example 3

[0063] The low thermal conductivity tin bath bottom brick comprises the following raw materials in parts by mass:

[0064]

[0065] The synthetic material comprises the following raw materials in parts by mass:

[0066]

[0067]

[0068] The preparation method of the synthetic material comprises the following steps: grinding and mixing plate-shaped corundum, pure calcium aluminate cement, plate-shaped clay, clay and food-grade cyclodextrin, adding water and extruding the mixture at 60 MPa, naturally drying the mixture in the shade for 1 day, drying the mixture at 110° C. for 68 hours, sintering the mixture in a high-temperature shuttle kiln, and crushing the mixture after sintering to obtain the synthetic material.

[0069] The sintering steps are: continuously heating to 350°C within 46 hours, continuously heating to 850°C within 70 hours, continuously heating to 1100°C within 70 hours, continuously heating to 1500°C within 70 hours, continuously heating to 1650°C within 96 hours, maintaining at 1650°C for 10 hours, continuously cooling to 1500°C within 92 hours, continuously cooling to 1350°C within 70 hours, continuously cooling to 1100°C within 70 hours, continuously cooling to 750°C within 70 hours, continuously cooling to 250°C within 70 hours, continuously cooling to 110°C within 20 hours, and continuously cooling to room temperature within 20 hours.

[0070] The high temperature cement is CA70 produced by Henan Li Te Refractory Material Co., Ltd., and its Al2O3 content is 68-77wt.%.

[0071] The pure calcium aluminate cement includes the following chemical components: Al2O3 80%, CaO 15%, Fe2O3 0.1%, and SiO2 4%.

[0072] The plate-like clay comprises the following chemical components: Al2O3 42-48%, SiO2 38-48%, Fe2O 3≤ 0.5%, TiO 2≤ 0.5%, K2O ≤ 1.5%, Na2O ≤ 0.5%; particle size is 1-3mm.

[0073] The clay powder includes the following chemical components: Al2O3 32-45%, SiO2 48-51%, Fe2O 3≤ 1.5%, TiO 2≤ 0.5%, K2O ≤ 0.5%, Na2O ≤ 0.5%; particle size less than 1mm.

[0074] The method for preparing the low thermal conductivity tin bath bottom brick comprises the following steps:

[0075] (1) Preparation of green body: The synthetic material, microporous mullite aggregate, pure calcium aluminate cement and high temperature cement are completely mixed and poured into a mold, and then formed by high-frequency vibration to obtain a green body;

[0076] (2) Sintering: sintering in a high temperature shuttle kiln at 1500-1550℃ for 36h;

[0077] (3) Grinding: After cutting and grinding, the low thermal conductivity tin bath bottom brick is obtained.

[0078] Comparative Example 1

[0079] The same as Example 1, except that the microporous mullite aggregate in the synthetic material is removed.

[0080] The embodiments and comparative examples were tested, and the test results are as follows:

[0081] Table 1 Test results

[0082]

[0083]

[0084] The bulk density and porosity are determined using GB / T 2997-2015 Test method for bulk density, apparent porosity and true porosity of dense shaped refractory products; the room temperature compressive strength is determined using GB / T5072-2008 Test method for room temperature compressive strength of refractory materials; and the hydrogen diffusion rate is determined using JC / T926-2003 "Tin bath bottom bricks for float glass (Appendix A Test method for hydrogen diffusion)".

[0085] After removing the microporous mullite from Example 1, the volume density will increase and the porosity will decrease, resulting in enhanced load softening and pressure resistance. However, the low thermal conductivity tin bath bottom brick is to reduce the thermal conductivity to achieve better insulation and energy saving. The effect of reducing costs while increasing the yield rate requires a lower thermal conductivity coefficient. Therefore, although other items of Example 1 are enhanced, the thermal conductivity is too high.

Claims

1. A low thermal conductivity tin bath bottom brick, characterized in that: Including the following raw materials in parts by weight: 45-70 parts of synthetic material; 10-16 parts of microporous mullite aggregate; 5-7 parts of pure calcium aluminate cement; 11-25 parts of high temperature cement; The synthetic material comprises the following raw materials in parts by mass: 15-25 parts of tabular corundum; 20-30 parts of pure calcium aluminate cement; 40-50 parts of plate clay; 3-7 parts clay powder; 3-7 parts of food-grade cyclodextrin; 1-5 parts water; The preparation method of the microporous mullite aggregate comprises the following steps: grinding alumina and quartz sand to a size of less than 100 mesh and drying to remove moisture, wherein the alumina is an industrial alumina raw material with a mass ratio of more than 98%, and the SiO2 in the quartz sand is greater than 99%; mixing the alumina and quartz sand in a mass ratio of 3:1, first adding the alumina and then adding the quartz sand to obtain a uniformly mixed mullite raw material; the mullite raw material is evenly divided into four portions and put into an electric furnace for melting at 2000±100°C, 200V voltage, and 1800±200A current for 60 minutes; blowing air upward from a bottom blowing pipe to form pores, wherein the air flow rate in the blowing pipe is 6mL / min and the bubble size is 0.5-1mm; stirring is simultaneously started at a rotation speed of 2000r / min; after 5 minutes, the temperature is rapidly lowered to room temperature within 10 minutes, and the particles are crushed to 2-5mm, thereby obtaining the microporous mullite aggregate; The preparation method of the synthetic material comprises: grinding and mixing plate-shaped corundum, pure calcium aluminate cement, plate-shaped clay, clay and food-grade cyclodextrin, adding water and extruding at 60-75 MPa, naturally drying in the shade for 1-2 days, then drying at 50-110° C. for 68-76 hours, sintering in a high-temperature shuttle kiln, and crushing after sintering to obtain the synthetic material. The particle size of the synthetic material is 3-6 mm. The sintering steps are: continuously heating to 350°C within 46-50 hours, continuously heating to 850°C within 70-74 hours, continuously heating to 1100°C within 70-74 hours, continuously heating to 1500°C within 70-74 hours, continuously heating to 1650°C within 96-120 hours, maintaining at 1650°C for 10-14 hours, continuously cooling to 1500°C within 92-100 hours, continuously cooling to 1350°C within 70-74 hours, continuously cooling to 1100°C within 70-74 hours, continuously cooling to 750°C within 70-74 hours, continuously cooling to 250°C within 70-74 hours, continuously cooling to 110°C within 20-28 hours, and continuously cooling to room temperature within 20-28 hours.

2. The low thermal conductivity tin bath bottom brick according to claim 1, characterized in that: The Al2O3 content of the high temperature cement is 68-77wt.%.

3. The low thermal conductivity tin bath bottom brick according to claim 1, characterized in that: The pure calcium aluminate cement includes the following chemical components: Al2O3 80-85%, CaO 10-15%, Fe2O3 0.1%, and SiO2 3-7%.

4. The low thermal conductivity tin bath bottom brick according to claim 1, characterized in that: The plate-like clay includes the following chemical components: Al2O3 42-48%, SiO2 38-48%, Fe2O3≤0.5%, TiO2≤0.5%, K2O≤1.5%, and Na2O≤0.5%; and the particle size is 1-3 mm.

5. The low thermal conductivity tin bath bottom brick according to claim 1, characterized in that: The clay powder includes the following chemical components: Al2O3 32-45%, SiO2 48-51%, Fe2O3≤1.5%, TiO2≤0.5%, K2O≤0.5%, Na2O≤0.5%; and the particle size is less than 1 mm.

6. A method for preparing the low thermal conductivity tin bath bottom brick according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Preparation of green body: The synthetic material, microporous mullite aggregate, pure calcium aluminate cement and high temperature cement are completely mixed and poured into a mold, and then formed by high-frequency vibration to obtain a green body; (2) sintering; (3) Grinding: After cutting and grinding, the low thermal conductivity tin bath bottom brick is obtained.

7. The method for preparing the low thermal conductivity tin bath bottom brick according to claim 6, characterized in that: The sintering is carried out in a high-temperature shuttle kiln at 1500-1550° C. for 36-48 hours.

Images