A carbon brick with high resistivity and low thermal conductivity and its manufacturing method

Abstract

This invention relates to the field of carbon technology and proposes a carbon brick with high resistivity and low thermal conductivity, comprising the following raw materials in parts by weight: 90-100 parts carbon black particles, 15-20 parts graphite oxide powder, 8-10 parts modified magnesium oxide powder, and 10-20 parts binder A; the carbon black particles are obtained by mixing and granulating carbon black and binder B; the modified magnesium oxide powder is obtained by modifying magnesium oxide powder with nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid. This technical solution solves the problem of low resistivity and high thermal conductivity in existing carbon bricks.

Description

Technical Field

[0001] This invention relates to the field of carbon materials technology, specifically to a carbon brick with high resistivity and low thermal conductivity and its manufacturing method. Background Technology

[0002] Bulk carbon materials, such as electrically calcined coal, carbon raisers, graphitized petroleum coke, and lithium-ion battery anodes, require treatment at temperatures exceeding 2000°C before use. This high-temperature treatment is typically carried out in high-temperature furnaces, including electrically calcined furnaces, vertical continuous graphitization furnaces, and ultra-high-temperature electrothermal fluidized bed furnaces. Since ordinary refractory materials are insufficient for the heat treatment temperatures exceeding 2000°C, block carbon materials, such as carbon bricks or graphite bricks, are needed to line the high-temperature furnace. Ordinary block carbon materials are manufactured using calcined petroleum coke, pitch coke, anthracite, and metallurgical coke as aggregates, and pitch and resin as binders, through processes such as crushing, screening, grinding, batching, mixing, molding, firing, and graphitization to produce carbon bricks or graphite bricks.

[0003] Carbon bricks or graphite bricks manufactured using ordinary processes can withstand temperatures above 2000℃ and have high strength. However, high-temperature furnaces rely entirely on electrical energy as a heat source to heat-treat granular carbon materials. Under specific operating conditions, the resistivity of the furnace lining material needs to be greater than 300 μΩ·m to facilitate the efficient operation of the high-temperature furnace. Ordinary carbon bricks or graphite bricks are good conductors of electricity. The resistivity of ordinary carbon bricks is usually between 30 and 60 μΩ·m, and that of ordinary graphite bricks is usually between 8 and 12 μΩ·m. These conditions cannot meet the electrical insulation requirements of the furnace lining material under specific operating conditions of high-temperature furnaces.

[0004] In addition, in order to save energy and reduce heat dissipation from the furnace body, high-temperature furnace lining materials are required to have properties such as high temperature resistance and high strength, and often also a thermal conductivity of less than 1 W / (m·K) to achieve the effect of heat insulation. However, ordinary carbon bricks or graphite bricks have relatively high thermal conductivity. The thermal conductivity of ordinary carbon bricks is usually between 3 and 10 W / (m·K), and the thermal conductivity of ordinary graphite bricks is usually between 80 and 120 W / (m·K), which obviously cannot meet the requirements of high-temperature furnaces for the heat insulation of furnace lining materials. Summary of the Invention

[0005] This invention proposes a carbon brick with high resistivity and low thermal conductivity and its manufacturing method, which solves the problem of low resistivity and high thermal conductivity of carbon bricks in related technologies.

[0006] The technical solution of the present invention is as follows:

[0007] This invention proposes a carbon brick with high resistivity and low thermal conductivity, comprising the following raw materials in parts by weight: 90-100 parts carbon black particles, 15-20 parts graphite oxide powder, 8-10 parts modified magnesium oxide powder, and 10-20 parts binder A.

[0008] The carbon black particles are obtained by mixing and granulating carbon black and binder B.

[0009] The modified magnesium oxide powder is obtained by modifying magnesium oxide powder with nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid.

[0010] As a further technical solution, the total mass of the nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid is 3% to 5% of the mass of magnesium oxide powder.

[0011] As a further technical solution, the total mass of the nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid is 4% of the mass of magnesium oxide powder.

[0012] As a further technical solution, the mass of the nonylphenol polyether-10 carboxylic acid is 60% to 70% of the sum of the masses of nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid.

[0013] As a further technical solution, the mass of the nonylphenol polyether-10 carboxylic acid is 65% of the sum of the masses of nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid.

[0014] As a further technical solution, the preparation method of the modified magnesium oxide powder includes the following steps: adding magnesium oxide powder to an ethanol solution, mixing evenly, adjusting to acidity, adding nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid, and modifying to obtain modified magnesium oxide powder.

[0015] As a further technical solution, the modification temperature is 40~50℃ and the modification time is 60~80min.

[0016] As a further technical solution, the ethanol solution is composed of anhydrous ethanol and water in a volume ratio of 1:9.

[0017] As a further technical solution, the binder A is composed of coal tar pitch and anthracene oil.

[0018] As a further technical solution, the binder A is composed of coal tar pitch and anthracene oil in a mass ratio of 2:8.

[0019] As a further technical solution, the method for preparing the carbon black particles includes the following steps: mixing carbon black and binder B evenly, then granulating and drying to obtain carbon black particles.

[0020] As a further technical solution, the particle size of the carbon black particles is 0.1~5mm.

[0021] As a further technical solution, the granulation temperature is 80~90℃ and the granulation time is 1.5~2.5h.

[0022] As a further technical solution, the drying temperature is 150~180℃.

[0023] As a further technical solution, the carbon black includes one or more of natural gas semi-reinforcing carbon black, N660 carbon black, N774 carbon black, N990 carbon black, and N991 carbon black.

[0024] As a further technical solution, the carbon black is preferably natural gas semi-reinforcing carbon black.

[0025] As a further technical solution, the adhesive B is a resin adhesive, which includes one or more of phenolic resin solution, furan resin solution, and epoxy resin solution.

[0026] As a further technical solution, the resin binder is made by diluting the resin with one of the following solvents: water, methanol, ethanol, ethylene glycol, and acetone, so that the viscosity of the resin binder reaches 10~100 mPa·s.

[0027] As a further technical solution, the resin binder is preferably one of an aqueous solution of phenolic resin or an ethanol solution of furan resin.

[0028] As a further technical solution, the granulator includes one of a disc granulator, a double-roller extrusion granulator, and a vertical roller extrusion granulator.

[0029] As a further technical solution, the drying equipment includes one of an electric heating blower dryer and a tunnel kiln drying equipment.

[0030] The present invention also includes a method for preparing carbon bricks with high resistivity and low thermal conductivity, comprising the following steps: mixing the raw materials evenly, kneading, molding, and firing to obtain carbon bricks.

[0031] As a further technical solution, the calcination temperature is 750~1200℃, and the calcination time is 40~60min.

[0032] As a further technical solution, the molding pressure is 30~50 MPa.

[0033] As a further technical solution, the mixing time is 20-30 minutes.

[0034] As a further technical solution, the carbon bricks are used in masonry engineering.

[0035] The working principle and beneficial effects of this invention are as follows:

[0036] 1. In this invention, adding carbon black particles and graphite oxide powder as the main base materials of carbon bricks can improve the resistivity and reduce the thermal conductivity of carbon bricks. Adding magnesium oxide powder modified with nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid can form a dense cross-linked network with graphite oxide powder, and the carbon black particles are dispersed in the network structure, which can further reduce the thermal conductivity of carbon bricks and improve the compressive strength of carbon bricks. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] In the following examples and comparative examples,

[0039] The model number of the graphite oxide powder is BK2020062624, and the manufacturer is Suzhou Kaifa New Material Technology Co., Ltd.

[0040] The magnesium oxide powder has a mesh size of 100.

[0041] The coal tar pitch is grade 30, with a softening point of 80~130°C, and is manufactured by Hebei Zhengri Energy Technology Development Co., Ltd.

[0042] The anthracene oil is designated as ZR016, with a viscosity of ≤1.5 and a density of 1.04~1.1. The manufacturer is Hebei Zhengri Energy Technology Development Co., Ltd.

[0043] The semi-reinforcing carbon black made from natural gas is model 774, and the manufacturer is Guangzhou Lida Rubber Raw Material Trading Co., Ltd.

[0044] The phenolic resin is model 2123, with a density of 1.1 g / cm³, and is manufactured by Henan Huanshan Industrial Co., Ltd.

[0045] The furan resin is model HW55, and the manufacturer is Qingzhou Hengwei Materials Technology Co., Ltd.

[0046] The ethanol solution consists of anhydrous ethanol and water in a volume ratio of 1:9.

[0047] Example 1

[0048] A method for preparing a carbon brick with high resistivity and low thermal conductivity includes the following steps:

[0049] 90 parts of carbon black granules, 15 parts of graphite oxide powder, 8 parts of modified magnesium oxide powder, 2 parts of coal tar pitch and 8 parts of anthracene oil were added to a kneading pot, mixed evenly, kneaded for 30 minutes and then removed from the pot. The mixture was then transferred to a molding machine and pressed into shape at 30 MPa. Finally, it was calcined in a ring furnace at 750℃ for 60 minutes to obtain carbon bricks.

[0050] The preparation method of modified magnesium oxide powder includes the following steps:

[0051] Add 20g of magnesium oxide powder to 400mL of ethanol solution, mix well, adjust the pH to 5 with 1mol / L hydrochloric acid solution, add 0.52g of nonylphenol polyether-10 carboxylic acid and 0.28g of 2,3,4-trihydroxybenzoic acid, modify at 40℃ for 60min, filter, wash and dry to obtain modified magnesium oxide powder.

[0052] The method for preparing carbon black particles includes the following steps:

[0053] 110g of natural gas semi-reinforcing carbon black and 10g of 10mPa·s phenolic resin aqueous solution were added to a disc granulator, mixed evenly, granulated at 80℃ for 2.5h, and then dried in an electric hot air dryer at 150℃ to obtain carbon black granules.

[0054] Example 2

[0055] A method for preparing a carbon brick with high resistivity and low thermal conductivity includes the following steps:

[0056] 95 parts carbon black granules, 18 parts graphite oxide powder, 9 parts modified magnesium oxide powder, 3 parts asphalt and 12 parts anthracene oil were added to a kneading pot, mixed evenly, kneaded for 25 minutes, and then removed from the pot. The mixture was then transferred to a molding machine and pressed into shape at 40 MPa. Finally, it was calcined in a ring furnace at 1000℃ for 50 minutes to obtain carbon bricks.

[0057] The preparation method of modified magnesium oxide powder includes the following steps:

[0058] Add 20g of magnesium oxide powder to 400mL of ethanol solution, mix well, adjust the pH to 5 with 1mol / L hydrochloric acid solution, add 0.52g of nonylphenol polyether-10 carboxylic acid and 0.28g of 2,3,4-trihydroxybenzoic acid, modify at 45℃ for 55min, filter, wash and dry to obtain modified magnesium oxide powder.

[0059] The method for preparing carbon black particles includes the following steps:

[0060] 110g of natural gas semi-reinforcing carbon black and 10g of 50mPa·s phenolic resin aqueous solution were added to a disc granulator, mixed evenly, granulated at 85℃ for 2h, and then dried in an electric hot air dryer at 170℃ to obtain carbon black granules.

[0061] Example 3

[0062] A method for preparing a carbon brick with high resistivity and low thermal conductivity includes the following steps:

[0063] 100 parts of carbon black granules, 20 parts of graphite oxide powder, 10 parts of modified magnesium oxide powder, 4 parts of asphalt and 16 parts of anthracene oil were added to a kneading pot, mixed evenly, kneaded for 20 minutes, and then removed from the pot. The mixture was then transferred to a molding machine and pressed into shape at 50 MPa. Finally, it was calcined in a ring furnace at 1200℃ for 40 minutes to obtain carbon bricks.

[0064] The preparation method of modified magnesium oxide powder includes the following steps:

[0065] Add 20g of magnesium oxide powder to 400mL of ethanol solution, mix well, adjust the pH to 6 with 1mol / L hydrochloric acid solution, add 0.52g of nonylphenol polyether-10 carboxylic acid and 0.28g of 2,3,4-trihydroxybenzoic acid, modify at 50℃ for 50min, filter, wash and dry to obtain modified magnesium oxide powder.

[0066] The method for preparing carbon black particles includes the following steps:

[0067] 110g of natural gas semi-reinforcing carbon black and 10g of 100mPa·s furan resin ethanol solution were added to a disc granulator, mixed evenly, granulated at 90℃ for 1.5h, and then dried in an electric hot air dryer at 180℃ to obtain carbon black granules.

[0068] Example 4

[0069] The only difference between this embodiment and Example 1 is the addition of 0.39g of nonylphenol polyether-10 carboxylic acid and 0.21g of 2,3,4-trihydroxybenzoic acid.

[0070] Example 5

[0071] The only difference between this embodiment and Example 1 is the addition of 0.65g of nonylphenol polyether-10 carboxylic acid and 0.35g of 2,3,4-trihydroxybenzoic acid.

[0072] Example 6

[0073] The only difference between this embodiment and Example 1 is the addition of 0.48g of nonylphenol polyether-10 carboxylic acid and 0.32g of 2,3,4-trihydroxybenzoic acid.

[0074] Example 7

[0075] The only difference between this embodiment and Example 1 is the addition of 0.56g of nonylphenol polyether-10 carboxylic acid and 0.24g of 2,3,4-trihydroxybenzoic acid.

[0076] Example 8

[0077] The only difference between this embodiment and Example 1 is the addition of 0.40g of nonylphenol polyether-10 carboxylic acid and 0.40g of 2,3,4-trihydroxybenzoic acid.

[0078] Example 9

[0079] The only difference between this embodiment and Example 1 is the addition of 0.64g of nonylphenol polyether-10 carboxylic acid and 0.16g of 2,3,4-trihydroxybenzoic acid.

[0080] Comparative Example 1

[0081] The only difference between this comparative example and Example 1 is that the modified magnesium oxide powder was replaced with an equal amount of magnesium oxide powder.

[0082] Comparative Example 2

[0083] The only difference between this comparative example and Example 1 is that nonylphenol polyether-10 carboxylic acid is not added.

[0084] Comparative Example 3

[0085] The only difference between this comparative example and Example 1 is that 2,3,4-trihydroxybenzoic acid was not added.

[0086] Performance testing:

[0087] The carbon bricks obtained in Examples 1-9 and Comparative Examples 1-3 were tested for resistivity according to the method in GB / T 31838.3-2019 "Dielectric and resistive properties of solid insulating materials - Part 3: Resistive properties (DC) method - Surface resistance and surface resistivity". Their thermal conductivity was tested according to the method in GB / T 10294-2008 "Determination of steady-state thermal resistance and related properties of thermal insulation materials - Protective hot plate method". The test results are shown in Table 1.

[0088] Table 1. Performance test results of carbon bricks obtained in Examples 1-9 and Comparative Examples 1-3

[0089]

[0090] In this invention, compared with Example 1, Comparative Example 1 replaced the modified magnesium oxide powder with an equal amount of magnesium oxide powder, Comparative Example 2 did not add nonylphenol polyether-10 carboxylic acid, and Comparative Example 3 did not add 2,3,4-trihydroxybenzoic acid. The results showed that the resistivity of Comparative Examples 1 to 3 was lower than that of Example 1, and the thermal conductivity was higher than that of Example 1. This indicates that adding magnesium oxide powder modified with nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid to carbon bricks can increase the resistivity of carbon bricks and reduce the thermal conductivity.

[0091] Compared with Example 1, Examples 4-5 changed the mass ratio of nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid to magnesium oxide powder. The results showed that the resistivity of Examples 4-5 was lower than that of Example 1, and the thermal conductivity was higher than that of Example 1. This indicates that when the mass of nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid is 4% of the mass of magnesium oxide powder, the resistivity of the carbon brick can be further increased and the thermal conductivity can be reduced.

[0092] Compared to Example 1, Examples 6-9 changed the ratio of nonylphenol polyether-10 carboxylic acid in the total mass of nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid. The results showed that the resistivity of Examples 8-9 was lower than that of Examples 1 and 6-7, while the thermal conductivity was higher. This indicates that when the mass of nonylphenol polyether-10 carboxylic acid is 60%-70% of the total mass of nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid, the resistivity of the carbon brick can be further increased and the thermal conductivity reduced. Furthermore, the resistivity of Example 1 was higher than that of Examples 6-7, while the thermal conductivity was lower. This indicates that when the mass of nonylphenol polyether-10 carboxylic acid is 65% of the total mass of nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid, the resistivity of the carbon brick can be further increased and the thermal conductivity reduced.

[0093] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A carbon brick with high resistivity and low thermal conductivity, characterized in that, Raw materials comprising the following components by weight: 90-100 parts carbon black granules, 15-20 parts graphite oxide powder, 8-10 parts modified magnesium oxide powder, and 10-20 parts binder A; The carbon black particles are obtained by mixing and granulating carbon black and binder B. The modified magnesium oxide powder is obtained by modifying magnesium oxide powder with nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid; The method for preparing the modified magnesium oxide powder includes the following steps: adding magnesium oxide powder to an ethanol solution, mixing evenly, adjusting to acidity, adding nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid, and modifying to obtain modified magnesium oxide powder. The binder A is composed of coal tar pitch and anthracene oil; The adhesive B is a resin adhesive.

2. The high resistivity and low thermal conductivity carbon brick according to claim 1, characterized in that, The total mass of the nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid is 3% to 5% of the mass of magnesium oxide powder.

3. A high resistivity, low thermal conductivity carbon brick according to claim 1, characterized in that, The mass of the nonylphenol polyether-10 carboxylic acid is 60% to 70% of the combined mass of the nonylphenol polyether-10 carboxylic acid and 2,3,4-trihydroxybenzoic acid.

4. The high resistivity and low thermal conductivity carbon brick according to claim 1, characterized in that, The modification temperature is 40~50℃, and the modification time is 60~80min.

5. A carbon brick with high resistivity and low thermal conductivity according to claim 1, characterized in that, The carbon black includes one or more of the following: natural gas semi-reinforcing carbon black, N660 carbon black, N774 carbon black, N990 carbon black, and N991 carbon black.

6. The high resistivity and low thermal conductivity carbon brick according to claim 1, characterized in that, The resin binder includes one or more of phenolic resin solution, furan resin solution, and epoxy resin solution.

7. A method for preparing a high resistivity, low thermal conductivity carbon brick according to any one of claims 1 to 6, characterized in that, The process includes the following steps: mixing the raw materials evenly, kneading, shaping, and firing to obtain charcoal bricks.

8. The method for preparing a high resistivity, low thermal conductivity carbon brick according to claim 7, characterized in that, The roasting temperature is 750~1200℃, and the roasting time is 40~60min.

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