CCS paste for bottom of submerged arc furnace

Abstract

The invention relates to a CCS paste for the bottom of a submerged arc furnace. The CCS paste consists of 55-65 parts by weight of silicon carbide which is 4-0.5 mm and is used as a first aggregate, 30-40 parts by weight of silicon carbide powder which is used as a second aggregate, 5-15 parts by weight of a carbon-containing binder and 3-7 parts by weight of metal silicon micropowder, wherein the metal silicon micropowder is used for reacting with carbon in the carbon-containing binder in a high-temperature environment in the submerged arc furnace to form silicon carbide for filling aggregate gaps and bonding the aggregate. In a high-temperature environment in the submerged arc furnace, metal silicon micro powder reacts with carbon in a carbon-containing binder to form SiC used for filling aggregate gaps and bonding a first aggregate and a second aggregate, so that CCS paste for the bottom of the submerged arc furnace is converted into a silicon carbide integrated layer with higher oxidation resistance and scouring resistance than those of elemental carbon; slag is effectively prevented from permeating from gaps among carbon blocks at the bottom of the furnace, high-temperature molten metal at the bottom of the furnace can be prevented from puncturing the bottom of the furnace, and the service life of the submerged arc furnace is stable.

Description

Technical field:

[0001] The invention relates to the technical field of submerged arc furnace bottom protection, in particular to a CCS paste for a submerged arc furnace bottom. Background technology:

[0002] Currently, domestic submerged arc furnace linings utilize an insulation-based lining structure. This involves laying asbestos sheets on the base of the furnace floor, followed by a layer of lightweight insulation bricks, then a layer of high-alumina bricks or clay bricks, and a carbon brick roof. The furnace walls, from the inside out, consist of a layer of aluminum silicate fiber felt against the furnace shell steel, followed by a ring of lightweight insulation bricks, then a ring of high-alumina bricks or clay bricks, and finally an innermost working layer, with carbon bricks at the bottom. This lining structure is prone to slag, a smelting product of the high specific gravity, when smelting alloys such as silicon-manganese, ferronickel, and ferromanganese. Slag is highly corrosive to the furnace lining, potentially causing the high-temperature molten metal at the bottom to penetrate the furnace floor, shortening the life of the submerged arc furnace. To address this issue, existing technologies utilize cold-rammed paste to fill the gaps between carbon blocks to prevent slag corrosion.

[0003] The raw materials of cold-rammed paste mainly include aggregate, binder and additives. Among them, the main raw materials of aggregate composition are: (1) calcined anthracite. The anthracite used for cathode paste should be low-ash high-quality anthracite. The ash content of anthracite before calcination should be less than 10%. Calcined anthracite is divided into ordinary calcined anthracite (calcination temperature is 1200℃~1350℃) and high-temperature electric calcined anthracite (calcination temperature is 1500℃-2000℃); (2) metallurgical coke, which is generally ground into fine powder less than 0.5mm for use. Metallurgical coke has poor resistance to aluminum liquid and electrolyte erosion; (3) graphite fragments, which can improve the thermal conductivity and electrical conductivity of cathode paste and improve the resistance to electrolyte corrosion. At 960℃, the carbon materials with the best resistance to sodium corrosion are: graphite, electric calcined coal, gas calcined coal, metallurgical coke and petroleum coke. Therefore, domestic cold ramming paste production plants use calcined anthracite, metallurgical coke, prebaked anode blocks, raw graphitized electrodes, natural graphite, and some Petroleum coke is selected as aggregate; the main raw materials of the binder are: (1) high temperature asphalt (modified asphalt) with a softening point of 100℃~110℃ (ring and ball method). Although the softening point of high temperature asphalt is high, its various indicators are significantly better than those of medium temperature asphalt. The use of high temperature asphalt can not only improve the quality of carbon products, but also facilitate transportation and storage, and improve the working environment and working conditions; (2) medium temperature coal tar with a softening point of 75℃~95℃. The softening point of medium temperature asphalt is low, and the quality of the carbon products made from it is not as good as that of high temperature asphalt; (3) coal tar or anthracene oil can be used to adjust the softening point of the binder, but while they lower the softening point, they will also reduce the amount of coking of the binder, thereby reducing the physical and chemical indicators of the cold ramming paste. The binder used for cold ramming paste is required to have a lower softening point, so coal tar is mixed with coal tar or anthracene oil as the binder. The softening point of commonly used mixed binders is 15℃~46℃; the role of additives is to increase the coking amount of ramming paste, and its action mechanism is: (1) oxidizing coal tar; (2) causing asphalt molecules to associate into larger molecules. Additives with any of the above action mechanisms can increase the coking amount of asphalt, and increase the volume density and compressive strength of cold ramming paste.

[0004] However, after the existing cold-rammed paste is used to fill the gaps between the carbon blocks at the bottom of the blast furnace, since the aggregate is mainly carbon, the aggregate of the cold-rammed paste will react with the free oxygen in the furnace and be damaged in a high-temperature environment. At the same time, the carbon aggregate has poor anti-scouring performance, and slag will penetrate from the gaps between the carbon blocks at the bottom of the furnace or the high-temperature molten metal at the bottom of the furnace will also penetrate the bottom of the furnace, resulting in a reduction in the service life of the blast furnace. Summary of the invention:

[0005] In view of this, it is necessary to provide an oxidation-resistant and erosion-resistant CCS paste for a submerged arc furnace bottom.

[0006] A CCS paste for a submerged arc furnace bottom comprises 55-65 parts by weight of 4-0.5 mm silicon carbide as a first aggregate, 30-40 parts by weight of silicon carbide powder as a second aggregate, 5-15 parts by weight of a carbon-containing binder, and 3-7 parts by weight of metallic silicon powder. The metallic silicon powder reacts with carbon in the carbon-containing binder under the high temperature environment of the submerged arc furnace to form silicon carbide for filling gaps between aggregates and bonding the aggregates.

[0007] Preferably, the passing rate of 200-mesh aggregate in the second aggregate is 50-60%; and the passing rate of 200-mesh metal silicon powder in the metal silicon powder is 60-70%.

[0008] Preferably, the CCS paste for the bottom of the submerged arc furnace is produced as follows: the first aggregate, the second aggregate, and the metallic silicon powder are dry-mixed for 10 minutes, and the first aggregate, the second aggregate, and the metallic silicon powder are preheated during the mixing process at a preheating temperature range of 50 to 60°C;

[0009] A carbonaceous binder is added to the dry-mixed first aggregate, second aggregate, and metallic silicon powder for wet mixing to obtain CCS paste for the bottom of a submerged arc furnace. The mixing time is 15 minutes. During the mixing process, the temperature of the first aggregate, second aggregate, metallic silicon powder, and carbonaceous binder is maintained at 65-75°C.

[0010] Preferably, the weight proportion of the first aggregate is 60, the weight proportion of the second aggregate is 35, the weight proportion of the carbon-containing binder is 10, and the weight proportion of the metallic silicon powder is 5; the 200-mesh aggregate pass rate in the second aggregate is 55%; and the 200-mesh metallic silicon powder pass rate in the metallic silicon powder is 65%.

[0011] Preferably, the green bulk specific gravity of CCS paste for the bottom of the submerged arc furnace is in the range of 2.556 to 2.725 g / cm 3 .

[0012] Preferably, the pseudo specific gravity of the furnace bottom after burning CCS paste is in the range of 2.238 to 2.396 g / cm 3 , the typical compressive strength is 15MPa.

[0013] In the above-mentioned CCS paste for the bottom of the submerged arc furnace, under the high temperature environment inside the submerged arc furnace, the metallic silicon powder in the CCS paste for the bottom of the submerged arc furnace reacts with the carbon in the carbon-containing binder to form SiC for filling the gaps between the aggregates and bonding the aggregates. The CCS paste for the bottom of the submerged arc furnace finally obtained is converted into a silicon carbide integral layer with higher oxidation resistance and erosion resistance than that of carbon alone, thereby effectively preventing slag from penetrating through the gaps between the carbon blocks at the bottom of the furnace and the high-temperature molten metal at the bottom of the furnace from penetrating the furnace bottom, thereby ensuring the stable service life of the submerged arc furnace. Specific implementation method:

[0014] To make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be described clearly and completely below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0015] The present invention provides a further description of the specific embodiments of the present invention in order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention and to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable.

[0016] It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention; the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as there is no conflict between them; based on the embodiments or examples in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0017] The present application provides a CCS (Ccarbon and "silicon carbide" and "metallic silicon") paste for the bottom of an electric arc furnace, which is composed of 55 to 65 parts by weight of 4 to 0.5 mm silicon carbide as a first aggregate, 30 to 40 parts by weight of silicon carbide powder as a second aggregate, 5 to 15 parts by weight of a carbon-containing binder, and 3 to 7 parts by weight of metallic silicon powder; wherein the metallic silicon powder is used to react with the carbon in the carbon-containing binder under the high temperature environment in the electric arc furnace to form a paste for filling the gaps between the aggregates. Specifically, after the submerged arc furnace starts working, the CCS paste used to fill the gaps between the carbon bricks at the bottom of the furnace is used. After the temperature of the bottom of the submerged arc furnace reaches about 700°C, the carbon-containing binder in the CCS paste used to fill the gaps between the carbon bricks at the bottom of the furnace is coked and produces micropores. As the temperature of the bottom of the submerged arc furnace reaches about 1380°C, a portion of the metallic silicon powder reacts with the carbon in the coked binder to form silicon carbide, and a portion of the metallic silicon powder reacts with the free oxygen in the furnace to prevent the low free oxygen from reacting with the carbon bricks at the bottom of the furnace. At the same time, the silicon carbide produced fills the pores and the gaps between the aggregates, and bonds aggregates of different particle sizes. The CCS paste used to fill the bottom of the submerged arc furnace forms an integrated layer of silicon carbide at high temperature and homogenizes the pores produced by the coking of the carbon-containing binder. In this way, the alloy melt in the submerged arc furnace is prevented from penetrating from the uncompacted aggregate gaps or the large pores formed after the coking of the carbon-containing binder, while the anti-scouring performance of the silicon carbide integrated layer can be guaranteed. The passing rate of 200-mesh aggregate in the second aggregate is 50-60%, and the passing rate of 200-mesh metal silicon powder in the metal silicon powder is 60-70%.

[0018] For example, the weight proportion of the first aggregate is 60, the weight proportion of the second aggregate is 35, the weight proportion of the carbon-containing binder is 10, and the weight proportion of the metallic silicon micropowder is 5; the pass rate of 200-mesh aggregate in the second aggregate is 55%; the pass rate of 200-mesh metallic silicon powder in the metallic silicon powder is 65%; the volatile matter of the carbon-containing binder is 71.5%, and the coking value is 35.3%.

[0019] Among them, the green body pseudo-density range of CCS paste used for the bottom of the submerged arc furnace is 2.556~2.725g / cm 3 The bottom of the submerged arc furnace is made of CCS paste, and the apparent specific gravity range after burning is 2.238~2.396g / cm 3 , the typical compressive strength is 15MPa.

[0020] Furthermore, the CCS paste for the furnace bottom of the submerged arc furnace is produced as follows: the first aggregate, the second aggregate, and the metallic silicon powder are dry-mixed for 10 minutes. During the mixing process, the first aggregate, the second aggregate, and the metallic silicon powder are preheated at a temperature of 50 to 60° C. to ensure that the carbon-containing binder is subsequently added to enhance its fluidity in a short period of time, thereby ensuring more uniform mixing of the materials.

[0021] Add carbon-containing binder to the dry-mixed first aggregate, second aggregate and metallic silicon powder for wet mixing to obtain CCS paste for the bottom of the submerged arc furnace. The mixing time is 15 minutes. During the mixing process, the temperature of the first aggregate, second aggregate, metallic silicon powder and carbon-containing binder is maintained at 65-75°C to prevent the carbon-containing binder from volatilizing and losing due to excessive temperature.

[0022] In the above-mentioned CCS paste for the bottom of the submerged arc furnace, under the high temperature environment inside the submerged arc furnace, the metallic silicon powder in the CCS paste for the bottom of the submerged arc furnace reacts with the carbon in the carbon-containing binder to form a silicon carbide paste for filling the gaps between the aggregates and bonding the first aggregate silicon carbide and the second aggregate silicon carbide. The CCS paste for the bottom of the submerged arc furnace finally obtained is converted into a silicon carbide integral layer with higher oxidation resistance and erosion resistance than that of carbon alone, thereby effectively preventing slag from penetrating from the gaps between the carbon blocks at the bottom of the furnace and the high-temperature molten metal at the bottom of the furnace from penetrating the furnace bottom, thereby ensuring the stable service life of the submerged arc furnace.

[0023] The following examples further illustrate the above technical solution:

[0024] Test formula 1: Prepare 3 pots of CCS paste for the bottom of the submerged arc furnace. The total weight of each pot of CCS paste for the bottom of the submerged arc furnace is 4000 kg. The weight of each component is shown in Table 1:

[0025] Table 1

[0026]

[0027] Silicon carbide, silicon carbide powder, and metallic silicon powder were first dry-mixed for 10 minutes to obtain a dry mixed material, and the preheating temperature was 50-60°C. A carbonaceous binder was added to the dry mixed material, and then wet-mixed for 15 minutes at a temperature of 70°C to finally obtain CCS paste for the bottom of a submerged arc furnace. The pseudo specific gravity of each pot of CCS paste for the bottom of a submerged arc furnace was measured, as shown in Table 2:

[0028] Table 2

[0029]

[0030] Workshop test formula 2: Prepare 3 pots of CCS paste for the bottom of the submerged arc furnace. The total weight of each pot of CCS paste for the bottom of the submerged arc furnace is 4000 kg. The weight of each component is shown in Table 3:

[0031] Table 3

[0032]

[0033] Silicon carbide, silicon carbide powder, and metallic silicon powder were first dry-mixed for 10 minutes to obtain a dry mixed material, and the preheating temperature was 50-60°C. A binder was added to the dry mixed material, and then wet-mixed for 15 minutes at a temperature of 70°C to finally obtain CCS paste for the bottom of a submerged arc furnace. The pseudo specific gravity of each pot of CCS paste for the bottom of a submerged arc furnace was measured, as shown in Table 4:

[0034] Table 4

[0035]

[0036]

[0037] Workshop test formula 3: Prepare 3 pots of CCS paste for the bottom of the submerged arc furnace. The total weight of each pot of CCS paste for the bottom of the submerged arc furnace is 4000 kg. The weight of each component is shown in Table 5:

[0038] Table 5

[0039]

[0040] Silicon carbide, silicon carbide powder, and metallic silicon powder were first dry-mixed for 10 minutes to obtain a dry mixed material, and the preheating temperature was 50-60°C. A binder was added to the dry mixed material, and then wet-mixed for 15 minutes at a temperature of 70°C to finally obtain CCS paste for the bottom of a submerged arc furnace. The pseudo specific gravity of each pot of CCS paste for the bottom of a submerged arc furnace was measured, as shown in Table 6:

[0041] Table 6

[0042]

[0043] Judging from the three formulas tested in the above workshop, the bulk density, green apparent specific gravity and fired apparent specific gravity of the CCS paste for the bottom of an electric arc furnace, which is composed of 60 parts by weight of 4-0.5 mm silicon carbide as the first aggregate, 35 parts by weight of silicon carbide powder as the second aggregate, 3 parts by weight of a carbon-containing binder and 5 parts by weight of metallic silicon powder, are better than those of the other two formulas.

Claims

1. A CCS paste for a submerged arc furnace bottom, characterized by: The invention is composed of 55 to 65 parts by weight of 4 to 0.5 mm silicon carbide as the first aggregate, 30 to 40 parts by weight of silicon carbide powder as the second aggregate, 5 to 15 parts by weight of a carbon-containing binder and 3 to 7 parts by weight of metallic silicon powder; wherein the metallic silicon powder is used to react with the carbon in the carbon-containing binder under the high temperature environment in the submerged arc furnace to form silicon carbide for filling the gaps between the aggregates and bonding the aggregates.

2. The CCS paste for the bottom of a submerged arc furnace according to claim 1, characterized in that: The passing rate of 200-mesh aggregate in the second aggregate is 50-60%; the passing rate of 200-mesh metallic silicon powder in the metallic silicon powder is 60-70%.

3. The CCS paste for the bottom of a submerged arc furnace according to claim 2, characterized in that: The CCS paste for the bottom of the submerged arc furnace is produced as follows: the first aggregate, the second aggregate and the metallic silicon powder are dry-mixed for 10 minutes. During the mixing process, the first aggregate, the second aggregate and the metallic silicon powder are preheated at a temperature of 50-60°C. A carbonaceous binder is added to the dry-mixed first aggregate, second aggregate, and metallic silicon powder for wet mixing to obtain CCS paste for the bottom of a submerged arc furnace. The mixing time is 15 minutes. During the mixing process, the temperature of the first aggregate, second aggregate, metallic silicon powder, and carbonaceous binder is maintained at 65-75°C.

4. The CCS paste for the bottom of a submerged arc furnace according to claim 3, characterized in that: The weight parts of the first aggregate are 60, the weight parts of the second aggregate are 35, the weight parts of the carbon-containing binder are 10, and the weight parts of the metallic silicon powder are 5; the pass rate of 200-mesh aggregate in the second aggregate is 55%; the pass rate of 200-mesh metallic silicon powder in the metallic silicon powder is 65%.

5. The CCS paste for the bottom of a submerged arc furnace according to claim 4, characterized in that: The green bulk density of CCS paste for submerged arc furnace bottom is in the range of 2.556~2.725g / cm 3 .

6. The CCS paste for the bottom of a submerged arc furnace according to claim 4 or 5, characterized in that: The bottom of the submerged arc furnace is made of CCS paste, and the apparent specific gravity ranges from 2.238 to 2.396 g / cm 3 , the typical compressive strength is 15MPa.

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