Environment-friendly low-carbon magnesia carbon brick and preparation method thereof

Abstract

The invention relates to an environment-friendly low-carbon magnesia carbon brick and a preparation method thereof, and the environment-friendly low-carbon magnesia carbon brick comprises the following components in parts by weight: 70-85 parts of fused magnesia aggregate, 25-35 parts of magnesia powder, 3-5 parts of a composite antioxidant, 0.5-1 part of nano carbon black and 2-4 parts of nano carbon fiber. The nano carbon fiber is adopted as a binding agent, so that the strength and toughness of the magnesia carbon brick can be improved, the erosion resistance and thermal shock resistance of the magnesia carbon brick can be enhanced, and the magnesia carbon brick does not generate harmful gas to pollute the environment during heating and is environment-friendly. The nano carbon black can construct a continuous carbon network structure with relatively low carbon content and can be tightly combined with other raw materials in a magnesia carbon brick matrix to prevent the matrix from being wetted by slag, so that the erosion resistance of the magnesia carbon brick is improved, the carbon-containing resin powder can be softened in a high-temperature state, pores in the matrix are closed in the softening process, and the corrosion resistance of the magnesia carbon brick is improved. The compactness of the magnesia carbon brick is improved, and the strength, the high-temperature breaking strength and the erosion resistance of the magnesia carbon brick are further improved.

Description

Technical Field

[0001] The invention relates to the technical field of refractory materials, and in particular to an environmentally friendly low-carbon magnesium-carbon brick and a preparation method thereof. Background Art

[0002] Magnesia carbon bricks are mainly used for the lining of converters, AC arc furnaces, DC arc furnaces, slag lines of ladles, etc. As a composite refractory material, magnesia carbon bricks effectively utilize the strong slag erosion resistance of magnesia sand and the high thermal conductivity and low expansion of carbon, compensating for the biggest disadvantage of poor spalling resistance of magnesia sand. In the prior art, the carbon content in magnesia carbon bricks is generally 10% to 20%, with good thermal shock resistance and excellent slag and spalling resistance.

[0003] However, with the advancement of smelting technology and new requirements for refractory materials, the existing magnesia carbon bricks have been found to have the following problems in the long-term application process:

[0004] 1. As the lining material of special refining furnace, it has the side effect of increasing carbon on refined steel grades;

[0005] 2. The high carbon content of magnesia carbon bricks will lead to increased high-temperature oxidation, increased heat loss and waste of high-quality graphite resources;

[0006] 3. The binder used in the preparation of existing magnesium carbon bricks is phenolic resin. When heated, phenolic resin will produce harmful gases such as formaldehyde and phenol, which are harmful to human health and cause environmental pollution, which is not conducive to environmental protection.

[0007] Therefore, it is particularly important to prepare an environmentally friendly low-carbon magnesia-carbon brick. Summary of the invention

[0008] In order to overcome the defects of the prior art, the technical problem solved by the present invention is to provide an environmentally friendly low-carbon magnesium carbon brick and a preparation method thereof. The low-carbon magnesium carbon brick is prepared using nano-carbon black and nano-carbon fibers, which can reduce the carbon content of the magnesium carbon brick and reduce the generation of harmful gases.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] An environmentally friendly low-carbon magnesium carbon brick, calculated by weight, comprises:

[0011]

[0012] The magnesia is fused magnesia or large crystal fused magnesia, wherein MgO≥97%.

[0013] The composite antioxidant is a mixed powder of Al powder and Si powder.

[0014] The weight ratio of Al powder to Si powder in the mixed powder is (4-2):1.

[0015] The particle size of the nano carbon black is 10 to 100 nm.

[0016] A method for preparing an environmentally friendly low-carbon magnesium carbon brick, the specific steps are as follows:

[0017] 1) Ingredients: Mix fused magnesia aggregate, magnesia powder, composite antioxidant, nano carbon black and nano carbon fiber in proportion;

[0018] 2) Mixing: Mix the prepared fused magnesia aggregate, magnesia powder and nano-carbon fiber for 3 to 5 minutes; then add nano-carbon black and continue to mix and stir for 5 to 10 minutes; finally add the composite antioxidant and continue to mix and stir for 10 to 15 minutes;

[0019] 3) Molding: Add the mixed material into the prepared mold and press it into shape;

[0020] 4) Drying: Dry in a drying kiln at 200-250°C for 10-24 hours to obtain the finished product.

[0021] In the step 3), the pressing pressure ranges from 115 to 200 MPa, and the number of pressing times is greater than or equal to 15 times.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The present invention uses nano-carbon fibers as a binder, which can not only improve the strength and toughness of magnesium carbon bricks, but also enhance their corrosion resistance and thermal shock resistance. Compared with traditional phenolic resins, it does not produce harmful gases and pollute the environment when heated, and is environmentally friendly.

[0024] 2) In the present invention, nano carbon black has the characteristics of high specific area and can construct a continuous carbon network structure with a relatively lower carbon content. In addition, nano carbon black can be tightly combined with other raw materials in the magnesium carbon brick matrix to prevent the matrix from being wetted by slag, thereby improving the corrosion resistance of the magnesium carbon brick. The carbon-containing resin powder can soften at high temperature and close the pores in the matrix during the softening process, thereby improving the density of the magnesium carbon brick and further improving the strength, high-temperature flexural strength and corrosion resistance of the magnesium carbon brick.

[0025] 3) The present invention has the characteristics of simple process, environmental protection, energy saving, resource saving and low cost. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention are further described below:

[0027] Example 1

[0028] The present invention provides an environmentally friendly low-carbon magnesium carbon brick, which comprises, by weight:

[0029]

[0030]

[0031] The magnesia is fused magnesia or large crystal fused magnesia, wherein MgO≥97%.

[0032] The composite antioxidant is a mixed powder of Al powder and Si powder.

[0033] The weight ratio of Al powder to Si powder in the mixed powder is 4:1.

[0034] The particle size of the nano carbon black is 10 to 100 nm.

[0035] A method for preparing an environmentally friendly low-carbon magnesium carbon brick, the specific steps are as follows:

[0036] 1) Ingredients: Mix fused magnesia aggregate, magnesia powder, composite antioxidant, nano carbon black and nano carbon fiber in proportion;

[0037] 2) Mixing: Mix the prepared fused magnesia aggregate, magnesia powder and nano-carbon fiber for 3 minutes; then add nano-carbon black and continue to mix and stir for 5 minutes; finally add the composite antioxidant and continue to mix and stir for 12 minutes;

[0038] 3) Molding: Add the mixed material into the prepared mold and press it into shape;

[0039] 4) Drying: Dry in a drying kiln at 220°C for 24 hours to obtain the finished product.

[0040] In the step 3), the pressing pressure range is 150 MPa, and the number of pressing times is greater than or equal to 18 times.

[0041] Example 2

[0042] An environmentally friendly low-carbon magnesium carbon brick, calculated by weight, comprises:

[0043]

[0044] The magnesia is fused magnesia or large crystal fused magnesia, wherein MgO≥97%.

[0045] The composite antioxidant is a mixed powder of Al powder and Si powder.

[0046] The weight ratio of Al powder to Si powder in the mixed powder is 3:1.

[0047] The particle size of the nano carbon black is 10 to 100 nm.

[0048] A method for preparing an environmentally friendly low-carbon magnesium carbon brick, the specific steps are as follows:

[0049] 1) Ingredients: Mix fused magnesia aggregate, magnesia powder, composite antioxidant, nano carbon black and nano carbon fiber in proportion;

[0050] 2) Mixing: Mix the prepared fused magnesia aggregate, magnesia powder and nano-carbon fiber for 5 minutes; then add nano-carbon black and continue to mix and stir for 8 minutes; finally add the composite antioxidant and continue to mix and stir for 12 minutes;

[0051] 3) Molding: Add the mixed material into the prepared mold and press it into shape;

[0052] 4) Drying: Dry in a drying kiln at 220°C for 24 hours to obtain the finished product.

[0053] In the step 3), the pressing pressure range is 180 MPa, and the number of pressing times is greater than or equal to 20 times.

[0054] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. In addition, the various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An environmentally friendly low-carbon magnesium carbon brick, characterized in that: Calculated by weight, including:

2. The environmentally friendly low-carbon magnesium carbon brick according to claim 1, characterized in that: The magnesia is fused magnesia or large crystal fused magnesia, wherein MgO≥97%.

3. The environmentally friendly low-carbon magnesium carbon brick according to claim 1, characterized in that: The composite antioxidant is a mixed powder of Al powder and Si powder.

4. The environmentally friendly low-carbon magnesium carbon brick according to claim 3, characterized in that: The weight ratio of Al powder to Si powder in the mixed powder is (4-2):

1.

5. The environmentally friendly low-carbon magnesium carbon brick according to claim 1, characterized in that: The particle size of the nano carbon black is 10 to 100 nm.

6. A method for preparing an environmentally friendly low-carbon magnesium-carbon brick according to any one of claims 1 to 5, characterized in that: The specific steps are as follows: 1) Ingredients: Mix fused magnesia aggregate, magnesia powder, composite antioxidant, nano carbon black and nano carbon fiber in proportion; 2) Mixing: Mix the prepared fused magnesia aggregate, magnesia powder and nano-carbon fiber for 3 to 5 minutes; then add nano-carbon black and continue to mix and stir for 5 to 10 minutes; finally add the composite antioxidant and continue to mix and stir for 10 to 15 minutes; 3) Molding: Add the mixed material into the prepared mold and press it into shape; 4) Drying: Dry in a drying kiln at 200-250°C for 10-24 hours to obtain the finished product.

7. The method for preparing an environmentally friendly low-carbon magnesium carbon brick according to claim 6, characterized in that: In the step 3), the pressing pressure ranges from 115 to 200 MPa, and the number of pressing times is greater than or equal to 15 times.

Images