A method for prolonging the service life of a blast furnace after pouring of a hearth

Abstract

This invention relates to a method for extending the service life of a blast furnace after hearth casting, belonging to the field of ironmaking technology. This invention solves the problem of the generally short service life of existing hearth casting materials. S1: Reduce the amount of alkali metals (4.5 kg / t•Fe) fed into the furnace to ≤3.0 kg / t•Fe, and reduce the amount of zinc (0.4 kg / t•Fe) fed into the furnace to ≤0.15 kg / t•Fe; S2: Adjust the taphole depth (≤3000 mm) to 3000 mm~3600 mm; S3: Adjust the diameter of the taphole opening machine drill bit from 55~60 mm to 50~55 mm, and adjust the tapping rate from 6.5 t / min~7.5 t / min to 5.6~6.2 t / min; S4: Install drainage holes along the circumference at the taphole plane, 2 meters below the taphole plane, and 4 meters below the taphole plane. This invention maintains the mud jacket by controlling the content of alkali metals and zinc in the raw materials fed into the furnace, avoiding direct erosion of the refractory material at the tip of the taphole by molten iron during tapping. This significantly reduces the risk of corrosion of the hearth refractory by the raw materials fed into the furnace, and extends the service life of the blast furnace hearth refractory.

Description

Technical Field

[0001] This invention relates to the field of ironmaking technology, and more particularly to a method for extending the service life of a blast furnace after hearth casting. Background Technology

[0002] Extending the lifespan of blast furnaces is a goal pursued by modern blast furnace manufacturers, as it signifies stable production and improved economic efficiency. In recent years, with the continuous increase in blast furnace smelting intensity and the deterioration of fuel quality, some blast furnaces have frequently experienced severe hearth damage, preventing them from reaching their designed service life. Hearth damage forces blast furnaces to shut down for major overhauls, causing production interruptions, reduced output, significantly increased maintenance costs, and serious resource waste; it may even trigger safety risks, such as molten iron leakage, severely impacting the long-term stable operation and overall economic benefits of the blast furnace. Therefore, the industry typically employs hearth casting technology to repair and protect the blast furnace hearth. This technology involves casting refractory materials into the hearth lining to form an integral protective layer, repairing damaged areas, enhancing erosion resistance, and thus ensuring the safety and stability of the blast furnace and extending its service life. However, due to the inherent limitations of the casting materials, the service life of existing hearth casting materials is generally short, typically only about three years, which has become a major technical bottleneck restricting the extension of blast furnace lifespan. If the service life of hearth castables can be effectively extended, the stable operation time of the blast furnace can be significantly prolonged, further improving production efficiency and bringing greater economic benefits. Therefore, overcoming the problem of short service life of castables has become a key issue that urgently needs to be addressed in current blast furnace longevity technologies. Summary of the Invention

[0003] The present invention aims to solve the above-mentioned problems and thereby provide a method for extending the service life of a blast furnace after hearth casting.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a method for extending the service life of a blast furnace after hearth casting, specifically including the following steps: S1: Reduce the amount of alkali metals fed into the furnace from the original content of 4.5 kg / t•Fe to ≤3.0 kg / t•Fe, and reduce the amount of zinc fed into the furnace from the original content of 0.4 kg / t•Fe to ≤0.15 kg / t•Fe; S2: Adjust the original iron tap depth of ≤3000mm to 3000mm~3600mm; S3: The diameter of the original copier drill bit is reduced from 55~60mm to 50~55mm, and its iron tapping rate is reduced from 6.5 t / min~7.5 t / min to 5.6~6.2 t / min; S4: Drainage holes are set in three layers on the circumferential direction of the furnace shell, at the horizontal plane of the center line of the taphole and at elevations of 2 meters and 4 meters below it. S5: Control the temperature difference between the inlet and outlet water of the cooling water in the cooling wall of the furnace hearth to be between 1 and 2℃, control the temperature difference between the inlet and outlet water of the cooling water in the bottom water cooling pipe to be less than 1℃, and control the heat flux intensity of the furnace hearth to be ≤12000Kcal / (m²·h). S6: Set the upper limit of furnace shell temperature to 80℃, and add furnace shell temperature measuring couplers to areas with high temperatures; S7: Adjust the Si content in the original molten iron from 0.25%~0.35% to ≥0.4%, and adjust the S content in the original molten iron from 0.035%~0.050% to ≤0.030%; S8: Increase the temperature of molten iron from the original 1470℃~1490℃ to 1500℃~1520℃ or higher.

[0005] Furthermore, in S1, the amount of alkali metals and zinc fed into the furnace is reduced by decreasing the amount of steelmaking dust, blast furnace bag filter dust, and sintering electric field dust used in the sinter.

[0006] Furthermore, in S5, the temperature difference between the inlet and outlet water of the cooling water in the cooling wall, the temperature difference between the inlet and outlet water of the cooling water in the furnace bottom water cooling pipe, and the heat flow intensity of the furnace hearth are controlled by increasing the cooling water flow rate of the cooling wall and water cooling pipe, reducing the cooling water temperature, or using high-pressure water forced cooling measures in high-temperature areas.

[0007] Furthermore, in S6, the furnace shell temperature is controlled by adding an axial flow fan or by using water spraying on the furnace shell.

[0008] Furthermore, in S7, the Si content in the molten iron is adjusted by increasing the fuel ratio from 510 kg / t•Fe ~ 520 kg / t•Fe to 520 kg / t•Fe ~ 535 kg / t•Fe, and the S content in the molten iron is adjusted by increasing the slag basicity from the original 1.15 to 1.20 times to 1.20 to 1.25 times.

[0009] Furthermore, the basicity of the slag can be controlled by increasing the proportion of alkaline sinter or reducing the proportion of acidic pellets.

[0010] Furthermore, in S8, the temperature of the molten iron is increased by raising the blast temperature from 1180°C to 1190°C~1210°C.

[0011] Furthermore, the method also includes a gas leak emergency handling step: after the leak point is discovered, the gas gap between the furnace lining and the furnace shell corresponding to the leak point is grouted and sealed to block the gas escape path and restore the furnace shell temperature in that area to a safe range.

[0012] Furthermore, the cooling equipment for the tuyeres, hearth, and bottom of the blast furnace is periodically inspected and replaced.

[0013] Compared with the prior art, the present invention has the following advantages: This invention maintains the lining by controlling the content of alkali metals and harmful elements such as zinc in the raw materials fed into the furnace, preventing molten iron from directly eroding the refractory material at the taphole tip during tapping, and significantly reducing the risk of corrosion of the hearth castable by the raw materials. Through raw material control and optimization of sintering and pelletizing ore blending, the cyclic accumulation of harmful substances is effectively inhibited, fundamentally delaying the performance degradation of the castable due to chemical corrosion, and creating a prerequisite for its long-term stable operation. This invention establishes a reasonable cooling intensity to maintain the hearth lining in a stable thermal equilibrium state, avoiding thermal stress damage to the castable refractory caused by temperature fluctuations due to insufficient or excessive cooling. Simultaneously, moderately increasing the superheat temperature of the molten iron reduces the carburizing reaction that occurs when low-temperature molten iron comes into contact with carbon bricks, significantly reducing the possibility of premature failure due to abnormal chemical corrosion of the hearth. These multi-dimensional measures work synergistically to form a systematic long-life technical solution encompassing source control, key component strengthening, and overall thermal environment optimization. Together, they significantly extend the overall service life of the hearth castable repair layer, effectively reducing unplanned shutdowns and major overhauls of the blast furnace due to hearth problems. This ensures the long-term continuity, stability, and smooth operation of the production process, ultimately improving blast furnace operating rates and increasing output while reducing maintenance costs per ton of iron, achieving a simultaneous and significant improvement in production efficiency and economic benefits. Detailed Implementation

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0017] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0018] In the description of this invention, it should be understood that the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0019] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figure to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figure. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0020] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0021] In this embodiment, a method for extending the service life of a blast furnace after hearth casting specifically includes the following steps: S1: Reduce the amount of alkali metals fed into the furnace from the original content of 4.5 kg / t•Fe to ≤3.0 kg / t•Fe, and reduce the amount of zinc fed into the furnace from the original content of 0.4 kg / t•Fe to ≤0.15 kg / t•Fe; S2: Adjust the original iron tap depth of ≤3000mm to 3000mm~3600mm; S3: The diameter of the original copier drill bit is reduced from 55~60mm to 50~55mm, and its iron tapping rate is reduced from 6.5 t / min~7.5 t / min to 5.6~6.2 t / min; S4: Drainage holes are set in three layers on the circumferential direction of the furnace shell, at the horizontal plane of the center line of the taphole and at elevations of 2 meters and 4 meters below it. S5: Control the temperature difference between the inlet and outlet water of the cooling water in the cooling wall of the furnace hearth to be between 1 and 2℃, control the temperature difference between the inlet and outlet water of the cooling water in the bottom water cooling pipe to be less than 1℃, and control the heat flux intensity of the furnace hearth to be ≤12000Kcal / (m²•h). S6: Set the upper limit of furnace shell temperature to 80℃, and add furnace shell temperature measuring couplers to areas with high temperatures; S7: Adjust the Si content in the original molten iron from 0.25%~0.35% to ≥0.4%, and adjust the S content in the original molten iron from 0.035%~0.050% to ≤0.030%; S8: Increase the temperature of molten iron from the original 1470℃~1490℃ to 1500℃~1520℃ or higher.

[0022] By controlling the content of alkali metals and harmful elements such as zinc in the raw materials fed into the furnace, and maintaining the mud liner, the risk of corrosion of the hearth refractory by molten iron directly eroding the taphole refractory during tapping is significantly reduced. Through raw material control and optimization of sintering and pelletizing ore blending, the cyclic accumulation of harmful substances is effectively inhibited, fundamentally delaying the performance degradation of the refractory due to chemical corrosion and creating a prerequisite for its long-term stable operation. By establishing a reasonable cooling intensity, the hearth lining is maintained in a stable thermal equilibrium state, avoiding thermal stress damage to the refractory caused by temperature fluctuations due to insufficient or excessive cooling. Simultaneously, appropriately increasing the superheat temperature of the molten iron reduces the carburizing reaction that occurs when low-temperature molten iron comes into contact with carbon bricks, significantly reducing the possibility of premature failure due to abnormal chemical corrosion of the hearth.

[0023] In S2, by selecting a reasonable taphole depth, the mud sleeve can be properly maintained, the mud volume can be stabilized, and mud overflow and incomplete slag and iron removal can be avoided, which would affect taphole operation and prevent molten iron from directly eroding the refractory material at the taphole tip during tapping. Specifically, the mud sleeve must be thoroughly dried to prevent gaps in the taphole channel during tapping, which could cause gas to escape and raise the temperature of the cooling wall in the taphole area. In S3, a suitable taphole drill bit should be selected to significantly reduce molten iron circulation and taphole vortex, slowing down the erosion rate in the elephant's foot area. In S4, the drain hole needs to be drained regularly until visible gas overflows before the drain valve can be closed.

[0024] In S1, the amount of alkali metals and zinc fed into the furnace is reduced by decreasing the amount of steelmaking dust, blast furnace bag filter ash, and sintering electric field ash used in the sinter. Specifically, alkali metals cause premature softening of the furnace charge, leading to changes in the position of the softening zone, and intensify the gasification reaction of coke, causing coke fragmentation, resulting in poor blast furnace permeability, inducing fluctuations in blast furnace gas flow, causing the solidified iron layer at the front of the hearth castable to detach, and subsequently allowing high-temperature molten iron to directly erode the refractory material; zinc vapor deposition in the furnace lining gaps causes volume expansion, damaging the brick lining structure. Since the source of alkali metals and zinc is the sinter, the content of alkali metals and zinc is reduced by controlling the composition within the sinter.

[0025] In S5, the temperature difference between the inlet and outlet water of the cooling water in the cooling wall, the temperature difference between the inlet and outlet water of the cooling water in the furnace bottom water cooling pipe, and the heat flow intensity of the furnace hearth are controlled by increasing the cooling water flow rate of the cooling wall and water cooling pipe, reducing the cooling water temperature, or using high-pressure water forced cooling measures in high-temperature areas.

[0026] In S6, the furnace shell temperature is controlled by adding an axial flow fan or by using water spraying on the furnace shell.

[0027] In S7, the Si content in the molten iron is adjusted by increasing the fuel ratio from 510 kg / t•Fe ~ 520 kg / t•Fe to 520 kg / t•Fe ~ 535 kg / t•Fe, and the S content in the molten iron is adjusted by increasing the slag basicity from the original 1.15 to 1.20 times to 1.20 to 1.25 times. Adjusting the Si and S content in the molten iron ensures a certain viscosity, thereby reducing the erosion of the taphole and hearth sidewall brick lining by the molten iron.

[0028] The basicity of slag is controlled by increasing the proportion of basic sinter or decreasing the proportion of acidic pellets. Specifically, the basicity is the ratio of CaO to SiO2.

[0029] In S8, the blast temperature is increased from 1180℃ to 1190℃~1210℃ to raise the molten iron temperature. When the molten iron temperature reaches above 1500℃, the carbon content in the molten iron is close to saturation, reducing the carburizing effect between the molten iron and the carbon bricks.

[0030] The method also includes emergency handling steps for gas leaks: after a leak point is found, the gas gap between the furnace lining and the furnace shell corresponding to the leak point is sealed by grouting to block the gas escape path and restore the furnace shell temperature in that area to a safe range.

[0031] The cooling equipment for the tuyeres, hearth, and bottom of the blast furnace shall be periodically inspected and replaced. Specifically, damaged tuyeres shall be replaced promptly. When the cooling equipment at the hearth and bottom is damaged, the water flow shall be controlled in a timely manner to prevent water leakage into the furnace and abnormal corrosion of the carbon bricks.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extending the service life of a blast furnace after hearth casting, characterized in that, Specifically, the following steps are included: S1: Reduce the amount of alkali metals fed into the furnace from the original content of 4.5 kg / t•Fe to ≤3.0 kg / t•Fe, and reduce the amount of zinc fed into the furnace from the original content of 0.4 kg / t•Fe to ≤0.15 kg / t•Fe; S2: Adjust the original iron tap depth of ≤3000mm to 3000mm~3600mm; S3: The diameter of the original copier drill bit is reduced from 55~60mm to 50~55mm, and its iron tapping rate is reduced from 6.5 t / min~7.5t / min to 5.6~6.2 t / min; S4: Drainage holes are set in three layers on the circumferential direction of the furnace shell, at the horizontal plane of the center line of the taphole and at elevations of 2 meters and 4 meters below it. S5: Control the temperature difference between the inlet and outlet water of the cooling water in the cooling wall of the furnace hearth to be between 1 and 2℃, control the temperature difference between the inlet and outlet water of the cooling water in the bottom water cooling pipe to be less than 1℃, and control the heat flux intensity of the furnace hearth to be ≤12000Kcal / (m²·h). S6: Set the upper limit of furnace shell temperature to 80℃, and add furnace shell temperature measuring couplers to areas with high temperatures; S7: Adjust the Si content in the original molten iron from 0.25%~0.35% to ≥0.4%, and adjust the S content in the original molten iron from 0.035%~0.050% to ≤0.030%; S8: Increase the temperature of molten iron from the original 1470℃~1490℃ to 1500℃~1520℃ or higher.

2. The method for extending the service life of a blast furnace after hearth casting according to claim 1, characterized in that: In S1, the amount of alkali metals and zinc fed into the furnace is reduced by decreasing the amount of steelmaking dust, blast furnace bag filter dust, and sintering electric field dust in the sinter.

3. The method for extending the service life of a blast furnace after hearth casting according to claim 1, characterized in that: In S5, the temperature difference between the inlet and outlet water of the cooling water in the cooling wall, the temperature difference between the inlet and outlet water of the cooling water in the furnace bottom water cooling pipe, and the heat flow intensity of the furnace hearth are controlled by increasing the cooling water flow rate of the cooling wall and water cooling pipe, reducing the cooling water temperature, or using high-pressure water forced cooling measures in high-temperature areas.

4. The method for extending the service life of a blast furnace after hearth casting according to claim 1, characterized in that: In S6, the furnace shell temperature is controlled by adding an axial flow fan or by using water spraying on the furnace shell.

5. A method for extending the service life of a blast furnace after hearth casting according to claim 1, characterized in that: In S7, the Si content in the molten iron is adjusted by increasing the fuel ratio from 510 kg / t•Fe ~ 520 kg / t•Fe to 520 kg / t•Fe ~ 535 kg / t•Fe, and the S content in the molten iron is adjusted by increasing the slag basicity from the original 1.15 to 1.20 times to 1.20 to 1.25 times.

6. A method for extending the service life of a blast furnace after hearth casting according to claim 5, characterized in that: Slag alkalinity can be controlled by increasing the proportion of alkaline sinter or decreasing the proportion of acidic pellets.

7. A method for extending the service life of a blast furnace after hearth casting according to claim 1, characterized in that: In S8, the temperature of the molten iron is increased by raising the blast air temperature from 1180℃ to 1190℃~1210℃.

8. A method for extending the service life of a blast furnace after hearth casting according to claim 1, characterized in that: The method also includes emergency handling steps for gas leaks: after a leak point is found, the gas gap between the furnace lining and the furnace shell corresponding to the leak point is sealed by grouting to block the gas escape path and restore the furnace shell temperature in that area to a safe range.

9. A method for extending the service life of a blast furnace after hearth casting according to claim 1, characterized in that: The cooling equipment for the tuyeres, hearth, and bottom of the blast furnace shall be periodically inspected and replaced.