Method for prolonging service life of refractory material of top-bottom combined blown converter

Abstract

The invention discloses a method for prolonging the service life of refractory materials of a top-bottom combined blown converter, which comprises the following steps of: dividing the refractory materials of a converter bottom and a converter body into N areas by gas according to the number of bottom blowing elements, and monitoring the three-dimensional erosion condition of the refractory materials of the converter, according to the erosion condition of each area, the process control is as follows: when the erosion depth of a furnace bottom refractory material in a certain area of the converter is greater than or equal to 350mm and the erosion depth of a furnace body refractory material is less than 400mm, the proportion of bottom blowing natural gas in the area is increased to 13-15%, and when the carbon content in the later smelting period of the converter is less than or equal to 0.06%, bottom lance oxygen blowing is switched into bottom blowing argon gas; and when the erosion depth of the furnace bottom refractory material in a certain area of the converter is greater than or equal to 350mm and the erosion depth of the furnace body refractory material is greater than or equal to 400mm, the bottom blowing oxygen flow in the area is reduced by 10-15%, and the bottom blowing oxygen flow in other areas is increased by 10-15%. The service life of a single furnace bottom is prolonged to 1500 furnaces or above, and a foundation is laid for accumulative service of four furnace bottoms; refractory control of the furnace body can be enhanced, and the erosion rate is slowed down.

Description

Technical Field

[0001] This invention relates to the field of converter smelting technology, and in particular to a method for improving the service life of refractory materials in top-and-bottom combined blowing converters. Background Technology

[0002] The top-and-bottom blown converter (KOBM converter) achieves combined top-and-bottom blowing by simultaneously blowing oxygen from the top and introducing gases (such as oxygen, argon, or nitrogen) from the bottom, along with powder injection. To achieve the goal of high-efficiency smelting with uniform molten pool temperature and rapid reaction in large converters, the industry commonly uses enhanced bottom blowing intensity to improve the metallurgical kinetics of the molten pool. Bottom blowing gases include oxygen, nitrogen, and argon. The conventional bottom blowing gas volume in converters is controlled at 0.15 Nm³. 3 The bottom blowing gas volume of the KOBM converter is below 0.55-1.0 Nm³ / (min·t), while that of a conventional converter can reach 0.55-1.0 Nm³ / (min·t), which is about 10 times that of a conventional converter. Although this can significantly improve smelting efficiency, it causes serious refractory erosion problems, resulting in a severely insufficient service life of converter refractory, especially the refractory at the bottom of the furnace.

[0003] In existing technologies, the average lifespan of a single hearth in a KOBM converter is approximately 1200 heats. Due to the insufficient lifespan of the furnace body refractory, international practice dictates that a maximum of three hearths must be replaced. Therefore, the overall lifespan of the converter is generally 4000-5000 heats, far lower than the 6000-8000 heats of conventional converters. This significantly increases the cost of converter refractory materials, severely hindering the widespread application of the strong bottom-blowing smelting process. The core contradictions leading to this problem are: firstly, under strong bottom-blowing conditions, the strong flow of molten steel and the high-temperature oxidizing environment cause severe scouring and chemical erosion of the hearth refractory, and uneven bottom-blowing flow distribution easily creates localized erosion pits, leading to a shortened lifespan of the hearth refractory; secondly, the lifespan of the hearth and furnace body refractory materials is poorly coordinated—localized erosion of the hearth causes abnormal flow fields in the molten pool, exacerbating localized erosion of the furnace body refractory, resulting in a shortened lifespan of the furnace body refractory. Existing technologies lack control over furnace body refractory materials and fail to optimize the design of new furnace bottoms based on furnace body erosion conditions. As a result, after three furnace bottoms have been in service, the furnace body refractory materials have been severely eroded and cannot support the replacement of the fourth furnace bottom. The converter has to be shut down for maintenance, which limits the improvement of converter lifespan.

[0004] Existing technologies often extend refractory life through single methods such as increasing the MgO content in the slag and strengthening slag splashing for furnace protection. However, these methods cannot solve the rapid wear and tear of furnace body refractory under strong bottom blowing conditions, nor have they established a furnace bottom zone bottom blowing control method based on refractory erosion conditions, or a matching mechanism between the furnace bottom lining height and the furnace body refractory erosion conditions. This fails to overcome the problem of "localized strong erosion + mismatched furnace body lifespan," resulting in a maximum of three furnace bottoms that can be matched simultaneously. The industry has long faced the technical bottleneck of "the inability to simultaneously achieve efficient smelting with strong bottom blowing and long-term converter operation." Therefore, a comprehensive solution is urgently needed that balances improving the lifespan of a single furnace bottom, coordinated management of furnace body-furnace bottom refractory materials, and precise matching between the furnace bottom and furnace body. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for improving the service life of refractory materials in top and bottom combined blowing converters by synergistic control of refractory materials in the furnace body and furnace bottom.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: the refractory material of the furnace bottom and furnace body is divided into N regions according to the number of bottom blowing elements, the three-dimensional erosion of the converter refractory material is monitored, and the process control is carried out according to the erosion of each region as follows:

[0007] When the erosion depth of the refractory material at the bottom of a certain area of ​​the converter is ≥350mm and the erosion depth of the refractory material in the furnace body is <400mm, the proportion of bottom-blown natural gas in that area is increased to 13-15%. When the carbon content is ≤0.06% in the later stage of converter smelting, the bottom-blown oxygen is switched to bottom-blown argon.

[0008] When the erosion depth of the refractory material at the bottom of a certain area of ​​the converter is ≥350mm and the erosion depth of the refractory material in the furnace body is ≥400mm, the bottom-blown oxygen flow rate in that area shall be reduced by 10-15%, and the bottom-blown oxygen flow rate in other areas shall be increased by 10-15%.

[0009] When the erosion depth of the refractory material at the bottom of a certain area of ​​the converter is ≥500mm, the bottom blowing in that area is cancelled, and the gas volume of the bottom blowing elements in other areas is increased by 15-20%.

[0010] Furthermore, the area is divided as follows: draw center lines between adjacent rows and columns of bottom-blowing elements, with all center lines extending to the furnace bottom boundary, dividing the furnace bottom into N furnace bottom areas; draw dividing lines vertically upward from the intersection of each center line and the furnace bottom boundary, dividing the furnace body into N furnace body areas; the corresponding furnace bottom areas and furnace body areas are grouped into one area, dividing the refractory material inside the furnace into N areas.

[0011] Furthermore, for the converter, if the furnace life is 1000 heats < furnace bottom life ≤ 1500 heats, then the flow rate of lime powder injected in the later stage of smelting is controlled at 400-600 kg / min, and the total injection volume is 1.0-1.5 t / heat.

[0012] If the furnace bottom life of the converter is greater than 1500 heats, then the bottom-blown lime powder flow rate in the later stage of smelting should be maintained at 400-600 kg / min, and the total amount of injection should be 1.5-2.5 t / heat.

[0013] Furthermore, when the average height of the refractory material at the bottom gun position is ≤500mm, the furnace bottom should be replaced with a new one, and the replacement furnace bottom should have a construction height h. i+1 It satisfies the following equation (1).

[0014] (1)

[0015] Where w is the converter charge (kg); ρ is the density of the molten steel; h i+1 h1 is the refractory design height for replacing the (i+1)th hearth in the converter, in mm; h1 is the refractory height of the first hearth, in mm; r1 is the radius at the converter height h1 position, in mm; r i+1 The height h of the (i+1)th furnace bottom refractory i+1 The average radius of the furnace at the location of the first furnace bottom, in mm; R1 is the radius of the furnace at height H inside the converter, in mm; R i+1 It is the average radius of the furnace at the (i+1)th furnace bottom height H position, in mm; where H is calculated by the following formula (2),

[0016] (2).

[0017] The beneficial effects of adopting the above technical solution are as follows:

[0018] 1. This invention achieves phased bottom blowing and zoned control throughout the entire furnace life of the converter, dynamically regulating bottom blowing to extend the life of a single furnace bottom, thereby improving the life of a single furnace bottom, coordinating the management and control of furnace body and furnace bottom refractory materials, and precisely matching the furnace bottom and furnace body, effectively improving the service life of converter refractory materials.

[0019] 2. This invention constructs a synergistic solution of "single hearth life improvement + furnace body-hearth refractory synergy + new hearth refractory adaptation", achieving continuous service of all four hearths in a strong bottom-blown converter for the first time, breaking through the industry-standard limitation of three hearths. It achieves simultaneous improvement in the life of furnace body-hearth refractory materials, with the overall converter life exceeding 6300 heats, breaking the world record of 5600 heats.

[0020] 3. Significantly reduce refractory material costs. The lifespan of a single hearth is increased to over 1500 heats, and the cumulative service time of four hearths is extended, resulting in a 30% reduction in refractory material costs. At the same time, converter downtime is reduced, smelting efficiency is improved, and significant economic benefits are generated.

[0021] 4. Specifically address the refractory erosion problem under KOBM converter smelting conditions, provide technical support for the long-term stable operation of the converter steelmaking process, and promote the green and low-carbon transformation of the steelmaking process.

[0022] 5. This invention extends the lifespan of a single furnace bottom to over 1500 heats, laying the foundation for the cumulative service of four furnace bottoms; it strengthens the control of furnace body refractory materials and slows down their erosion rate; it accurately calculates the construction height of the new furnace bottom based on the real-time erosion degree of the furnace body, ensuring that the furnace body refractory materials do not fail prematurely during the service of each new furnace bottom, ultimately achieving continuous replacement of four furnace bottoms and extending the converter lifespan. Attached Figure Description

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] Figure 1 This is a schematic diagram of the refractory material area division of the furnace bottom as described in this invention;

[0025] Figure 2 This is a schematic diagram of the division of the refractory material area of ​​the furnace body according to the present invention. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to specific embodiments.

[0027] During the service life of a converter, its total lifespan is jointly determined by the synergistic matching degree between the lifespan of a single hearth, the number of hearth replacements, and the lifespan of the refractory material in the furnace body. This method for improving the refractory lifespan of a top-and-bottom combined blowing converter includes the following control processes:

[0028] (1) A bottom-blowing dynamic control strategy based on the three-dimensional erosion field of the furnace body to protect the refractory materials of the furnace bottom and furnace body: The three-dimensional erosion of the converter refractory materials is monitored by measuring the thickness of the furnace body. A laser thickness gauge can be used for measurement. The erosion depth of the converter refractory materials is measured every 4 to 5 heats, and the erosion depth of the furnace body and furnace bottom refractory materials is calculated. The traditional constant flow control is abandoned, and a bottom-blowing zone-differentiated bottom-blowing control strategy is adopted. The specific method is as follows:

[0029] Differentiated zone control of bottom blowing addresses localized deep pit erosion in the furnace bottom and body refractory materials: The furnace bottom and body refractory materials are divided into N zones based on the number of bottom blowing elements, where N equals the number of bottom blowing elements. The zones are divided as follows: center lines are drawn between adjacent rows and columns of bottom blowing elements, extending to the furnace bottom boundary, dividing the furnace bottom into N zones; vertical dividing lines are drawn upwards from the intersections of each center line and the furnace bottom boundary, dividing the furnace body into N zones; the corresponding upper and lower furnace bottom and furnace body zones are grouped into one zone, thus dividing the furnace refractory materials into N zones. Ideally, such as... Figure 1 and 2 As shown, there are six bottom-blowing elements arranged in two rows and three columns. The center of the furnace bottom is the origin, with the direction extending along the rows defined as the x-direction and the direction extending along the columns defined as the y-direction, where y-direction is 0° and x-direction is 90°. A center line is drawn between the two rows, extending to the furnace bottom boundary. The intersection points of the center lines between the rows and the furnace bottom boundary are located at 90° and -90° respectively. Two center lines are drawn between the three columns, extending to the furnace bottom boundary. The angles between the intersection points of the two center lines and the furnace bottom boundary and the y-direction are α, β, -β, and -α, where sinα = m / 2R and β = 180°-α. One center line between rows and two center lines divide the furnace bottom into six regions. Vertical dividing lines are drawn upwards from the intersection points of the three center lines and the furnace bottom boundary, dividing the furnace body into six furnace body regions. The angles between the six dividing lines and the y-direction are α, 90°, β, -β, -90°, and -α respectively.

[0030] When the erosion depth of the refractory material at the bottom of a certain area of ​​the converter is ≥350mm and the erosion depth of the refractory material in the furnace body is <400mm: the proportion of bottom-blown natural gas in that area is increased from 9-11% to 13-15 vol% to increase cooling intensity, while other areas remain unchanged; when the carbon content is ≤0.06wt% in the later stage of converter smelting, bottom-blown oxygen is switched to bottom-blown argon to protect the refractory material at the bottom through inert gas. The natural gas proportion is the ratio of the volumetric flow rate of natural gas to the volumetric flow rate of oxygen in the bottom-blowing element, and the bottom-blowing element has the function of bottom-blowing oxygen and natural gas.

[0031] When the erosion depth of the refractory material at the bottom of a certain area of ​​the converter is ≥350mm and the erosion depth of the refractory material in the furnace body is ≥400mm: the bottom-blown oxygen flow rate in that area is reduced by 10-15%, and the bottom-blown oxygen flow rate in other areas is increased by 10-15%. In this way, by increasing the steel flow rate in other areas and reducing the bottom-blowing intensity in that area, the steel flow rate is changed, the steel flow field is disrupted, the fixed "scouring channel" is destroyed, and the failure of specific parts of the furnace body due to long-term directional scouring is prevented, thereby achieving coordinated stability of the refractory materials at the bottom and furnace body.

[0032] When the erosion depth of the refractory material at the bottom of a certain area of ​​the converter is ≥500mm: cancel the bottom blowing in that area, and increase the gas volume of the bottom blowing elements in other areas by 15-20%; thereby ensuring the stability of the bottom blowing stirring intensity, preventing the local erosion at the bottom of the furnace from expanding further, and avoiding the erosion of the furnace body refractory material caused by the erosion pit at the bottom of the furnace.

[0033] (2) Extending the lifespan of single furnace bottom refractory and furnace body refractory through phased synergistic control based on furnace bottom life:

[0034] To address the erosion characteristics of the furnace bottom at different service stages, the flow rate of bottom-blown lime powder and the total iron content of the final slag are synergistically controlled. This extends the life of a single furnace bottom to over 1500 heats and slows down the erosion of the furnace body refractory materials by optimizing slag properties and reducing furnace body temperature. The specific control scheme is as follows:

[0035] Furnace bottom life ≤ 1000 furnaces: Controlled according to conventional process to ensure smelting efficiency.

[0036] For furnace bottom lifespans of 1000 heats to 1500 heats: In the later stages of smelting, when the carbon content in the molten steel pool is ≤0.35%, lime powder is injected at a flow rate of 400–600 kg / min and a total injection volume of 1.0–1.5 t / heat. This reduces the temperature of the furnace bottom and furnace body through physical heat absorption, while the lime powder provides efficiency for dephosphorization in the later stages, thereby reducing the total iron content in the final slag to 12–15 wt%. This achieves a low-oxidizing slag splashing effect, optimizes furnace protection, and forms a dense slag layer to protect the refractory materials of the furnace body.

[0037] Furnace bottom life > 1500 heats: In the later stage of smelting, when the C content of the molten steel pool is ≤ 0.35%, the bottom-blown lime powder flow rate is maintained at 400-600 kg / min, and the total amount of injection is 1.5-2.5 t / heat. This can further enhance the cooling and slag protection effect, and control the total iron content of the final slag at 11-13%, so that the life of a single furnace bottom exceeds 1500 heats. At the same time, it minimizes the erosion rate of the furnace body refractory and reserves sufficient furnace body life margin for the cumulative service of the four furnace bottoms.

[0038] (3) The precise design of the new furnace bottom lining height based on the degree of erosion of the furnace body refractory material supports the replacement of 4 furnace bottoms:

[0039] When the average height of the refractory material at the bottom lance position is ≤500mm, ideally when the average height of the refractory material within a 200mm radius around the bottom lance is ≤500mm, a new furnace bottom is required. The core innovation lies in accurately calculating the new furnace bottom lining height h based on the actual erosion level of the current furnace body refractory material using the following formula. i+1 This ensures that the furnace body refractory does not fail prematurely during the service life of the new furnace bottom, achieving continuous matching of the four furnace bottoms.

[0040] The height h of the new furnace bottom i+1 It satisfies the following equation (1).

[0041] (1)

[0042] Where w is the converter charge amount, in kg; ρ is the density of the molten steel, in g / mm³. 3 h i+1 h1 is the refractory design height for replacing the (i+1)th hearth in the converter, in mm; h1 is the refractory height of the first hearth, in mm; r1 is the radius at the converter height h1 position, in mm, i.e., the radius R of the hearth refractory material; r i+1 The height h of the (i+1)th furnace bottom refractory i+1 The average radius of the furnace at the location of the first furnace bottom, in mm; R1 is the radius of the furnace at height H inside the converter, in mm; R i+1 It is the average radius of the furnace at the (i+1)th furnace bottom height H position, in mm, obtained by a laser thickness gauge; where H is calculated by the following formula (2),

[0043] (2).

[0044] Radius r at different heights i+1 The thickness was obtained using a laser thickness gauge, and the refractory lining height h when the (i+1)th furnace bottom was replaced was obtained by solving equation (1) using an iterative method. i+1 .

[0045] Among them, r1 and R1 are known parameters obtained according to the converter refractory lining scheme, and H is calculated by equation (2). The furnace radius r at different heights was recorded by a thickness gauge. i+1 The new furnace bottom refractory material is higher than the original furnace bottom refractory material, resulting in an h-shaped difference. i+1 >h i In calculating h i+1 At that time, the refractory height h (initial value is h) i ), and the corresponding furnace radius r i+1 Substituting into equation (1), if the equation does not hold, increase the value of h, i.e., h = h + 1, and reconfirm the furnace radius r at h based on the thickness measurement. i+1 Substitute into equation (1); until the equation holds, that is, solve for the refractory height h of the new furnace bottom. i+1 .

[0046] The lining height calculated by this formula can accurately match the remaining life of the current furnace body refractory: when the first to third furnace bottoms are replaced, the furnace body refractory is prevented from being excessively eroded by optimizing the height of the furnace bottom refractory; when the fourth furnace bottom is put into service, the furnace body refractory can still maintain an effective thickness, ultimately achieving a cumulative service life of more than 6,000 furnaces for the four furnace bottoms.

[0047] Example 1:

[0048] After the converter body and furnace bottom refractory lining are completed, production will commence. After the first furnace bottom has a lifespan of ≥1000, the flow rate of lime powder injected into the furnace bottom during the later stages of smelting will be 400 kg / min, with a total amount controlled at 1.5 t / furnace; the average total iron content of the final slag will be controlled at 15%.

[0049] When the furnace bottom life reached 1084 heats, severe localized erosion occurred in the refractory material at the furnace bottom. The erosion depth in this area was 355 mm, exceeding 350 mm, while the erosion depth in the furnace body refractory material was less than 400 mm. The proportion of bottom-blown natural gas in this area was increased from 9% to 13% to enhance cooling intensity, while other areas remained unchanged. During the later stages of converter smelting, when the carbon content was ≤0.06%, bottom-blown oxygen was switched to bottom-blown argon.

[0050] When the furnace bottom life is 1389 heats, the refractory erosion depth of the furnace bottom is 366mm, which is greater than 350mm, and the refractory erosion depth of the furnace body is 442mm, which is ≥400mm. In this case, the bottom-blown oxygen flow rate in this area will be reduced by 10%, and the bottom-blown oxygen flow rate in other areas will be increased by 10%.

[0051] The furnace bottom life exceeds 1500 heats, and the flow rate of lime powder injected into the furnace bottom during the later stage of smelting is 600 kg / min, with a total amount controlled at 2.5 t / heat; the total iron content of the final slag is controlled at 13%.

[0052] When the furnace bottom life is 1592, the average refractory height at the bottom lance position is 496mm. If this is less than 500mm, the furnace bottom should be replaced. w is the converter charge amount, taken as 3 × 10⁻⁶. 5 kg; ρ is the density of molten steel, taken as 7.2 g / cm³. 3 h1 is the refractory height of the first furnace bottom, taken as 1400mm; r1 is the radius of the converter at height h1, i.e., the refractory radius of the furnace bottom, taken as 2310mm; R1 is the furnace radius at height H in the converter when the first furnace bottom is present, taken as 3225mm; the value of H is calculated to be 3117mm by formula (2). The average furnace radius R2 at height H of the second furnace bottom was measured to be 3367mm. After iterative calculation, the new furnace bottom and height h2 should be 1523mm. At this time, the average furnace radius r2 at height h2 is 2376mm.

[0053] Example 2:

[0054] After the converter hearth is replaced, production begins. Once the second hearth has a lifespan of ≥1000, the flow rate of lime powder injected into the hearth during the later stages of smelting is 600 kg / min, with a total amount controlled at 1.0 t / furnace; the average total iron content of the final slag is controlled at 12%.

[0055] When the furnace bottom life reached 1154 heats, severe localized erosion occurred in the furnace bottom refractory material. The erosion depth in this area was 385 mm, greater than 350 mm, while the erosion depth in the furnace body refractory material was less than 400 mm. The proportion of bottom-blown natural gas in this area was increased from 11% to 15% to increase cooling intensity, while other areas remained unchanged.

[0056] When the carbon content is ≤0.06% in the later stage of converter smelting, bottom blowing oxygen is switched to bottom blowing argon. When the furnace age is 1485 heats, the refractory erosion depth at the furnace bottom reaches 522mm, which is greater than 500mm, so bottom blowing at this location is cancelled; the gas volume of bottom blowing elements in other areas is increased by 15%.

[0057] The furnace bottom life exceeds 1500 heats, and the flow rate of lime powder injected into the furnace bottom during the later stage of smelting is 400 kg / min, with a total amount controlled at 1.5 t / heat; the total iron content of the final slag is controlled at 11%.

[0058] When the furnace bottom life is 1521, the average refractory height at the bottom lance position is 494mm. If this is less than 500mm, the furnace bottom should be replaced. w is the converter charge amount, taken as 3×10. 5 kg; ρ is the density of molten steel, taken as 7.2 g / cm³. 3h1 is the refractory height of the first furnace bottom, taken as 1400mm; r1 is the radius of the converter at height h1, i.e., the refractory radius of the furnace bottom, taken as 2310mm; R1 is the furnace radius at height H in the converter when the first furnace bottom is present, taken as 3225mm; after unifying the units, the calculated value of H is 3117mm. The average furnace radius R3 at height H of the third furnace bottom was measured to be 3481mm. After iterative calculation, the new furnace bottom with height h3 should be 1639mm. At this point, the average furnace radius r3 at height h3 is 2485mm.

[0059] Example 3:

[0060] After the converter hearth is replaced, production begins. After the third hearth has a lifespan of ≥1000, the flow rate of lime powder injected into the hearth during the later stages of smelting is 500 kg / min, and the total amount is controlled at 1.5 t / furnace; the average total iron content of the final slag is controlled at 12%.

[0061] When the furnace bottom life reached 1421 heats, severe localized erosion occurred in the furnace bottom refractory material. The erosion depth in this area was 362 mm, exceeding 350 mm, while the erosion depth in the furnace body refractory material was 408 mm, with a erosion depth ≥400 mm. The bottom-blown oxygen flow rate in this area was reduced by 10%, while the bottom-blown oxygen flow rate in other areas was increased by 15%.

[0062] The furnace bottom life exceeds 1500 heats, and the flow rate of lime powder injected into the furnace bottom during the later stage of smelting is 500 kg / min, with a total amount controlled at 2.5 t / heat; the total iron content of the final slag is controlled at 13%.

[0063] When the furnace bottom life reaches 1581, the average refractory height at the bottom lance position is 484mm. If this is less than 500mm, the furnace bottom should be replaced. w is the converter charge amount, taken as 3 × 10⁻⁶. 5 kg; ρ is the density of molten steel, taken as 7.2 g / cm³. 3 h1 is the refractory height of the first furnace bottom, taken as 1400mm; r1 is the radius of the converter at height h1, i.e., the refractory radius of the furnace bottom, taken as 2310mm; R1 is the furnace radius at height H in the converter when the first furnace bottom is present, taken as 3225mm; after unifying the units, the calculated value of H is 3117mm. The average furnace radius R4 at height H of the fourth furnace bottom was measured to be 3569mm. After iterative calculation, the new furnace bottom with height h4 should be 1727mm. At this point, the average furnace radius r4 at height h4 is 2585mm.

[0064] Example 4:

[0065] After the converter hearth is replaced, production begins. After the fourth hearth has a lifespan of ≥1000, the flow rate of lime powder injected into the hearth during the later stages of smelting is 400 kg / min, and the total amount is controlled at 1.5 t / furnace; the average total iron content of the final slag is controlled at 12%.

[0066] When the furnace bottom life reached 1182 heats, severe localized erosion occurred in the furnace bottom refractory material. The erosion depth in this area was 385 mm, greater than 350 mm, while the erosion depth in the furnace body refractory material was less than 400 mm. The bottom-blown natural gas ratio in this area was increased from 10% to 15% to increase cooling intensity, while other areas remained unchanged.

[0067] When the carbon content is ≤0.06% in the later stage of converter smelting, the bottom lance oxygen is switched to bottom lance argon.

[0068] When the furnace bottom life is 1321 heats, the refractory erosion depth of the furnace bottom is 366mm, which is greater than 350mm, and the refractory erosion depth of the furnace body is 442mm, which is ≥400mm. The bottom-blown oxygen flow rate in the affected area is reduced by 15%, and the bottom-blown oxygen flow rate in other areas is increased by 10%.

[0069] The furnace bottom life exceeds 1500 heats, and the flow rate of lime powder injected into the furnace bottom during the later stage of smelting is 500 kg / min, with a total amount controlled at 2.0 t / heat; the total iron content of the final slag is controlled at 12%.

[0070] When the furnace bottom life reaches 1556 heats, the average height of the refractory material at the furnace bottom minus the minimum height of the refractory material is 374 mm, which is greater than 350 mm. Furthermore, severe erosion occurs in the refractory material thickness near this location, with an erosion depth reaching 412 mm, which is greater than 400 mm. The bottom lance closest to the lowest point of the furnace bottom refractory material is blocked, and bottom blowing at that location is cancelled; the gas volume of bottom blowing elements in other areas is increased by 20%. When the furnace bottom life reaches 1634 heats, the average refractory material height at the bottom lance location is 469 mm, which is less than 500 mm, indicating the converter's lifespan has expired.

Claims

1. A method for improving the service life of refractory materials in a top-and-bottom combined blowing converter, characterized in that: The refractory materials of the furnace bottom and furnace body are divided into N regions according to the number of bottom blowing elements. The three-dimensional erosion of the converter refractory materials is monitored, and the process control is as follows based on the erosion status of each region: When the erosion depth of the refractory material at the bottom of a certain area of ​​the converter is ≥350mm and the erosion depth of the refractory material in the furnace body is <400mm, the proportion of bottom-blown natural gas in that area is increased to 13-15%. When the carbon content is ≤0.06% in the later stage of converter smelting, the bottom-blown oxygen is switched to bottom-blown argon. When the erosion depth of the refractory material at the bottom of a certain area of ​​the converter is ≥350mm and the erosion depth of the refractory material in the furnace body is ≥400mm, the bottom-blown oxygen flow rate in that area shall be reduced by 10-15%, and the bottom-blown oxygen flow rate in other areas shall be increased by 10-15%. When the erosion depth of the refractory material at the bottom of a certain area of ​​the converter is ≥500mm, the bottom blowing in that area is cancelled, and the gas volume of the bottom blowing elements in other areas is increased by 15-20%.

2. The method for improving the service life of refractory materials in a top-and-bottom combined blowing converter according to claim 1, characterized in that, The area is divided as follows: draw center lines between adjacent rows and columns of bottom-blowing elements, with all center lines extending to the furnace bottom boundary, dividing the furnace bottom into N furnace bottom areas; draw dividing lines vertically upward from the intersection of each center line and the furnace bottom boundary, dividing the furnace body into N furnace body areas; the corresponding furnace bottom areas and furnace body areas are grouped into one area, dividing the refractory material inside the furnace into N areas.

3. The method for improving the service life of refractory materials in a top-and-bottom combined blowing converter according to claim 1, characterized in that: For the converter, if the furnace life is between 1000 heats and 1500 heats, the flow rate of lime powder injected during the later stage of smelting should be controlled at 400-600 kg / min, and the total injection volume should be 1.0-1.5 t / heat. If the furnace bottom life of the converter is greater than 1500 heats, then the bottom-blown lime powder flow rate in the later stage of smelting should be maintained at 400-600 kg / min, and the total amount of injection should be 1.5-2.5 t / heat.

4. A method for improving the service life of refractory materials in a top-and-bottom combined blowing converter according to claim 1, 2, or 3, characterized in that: When the average height of the refractory material at the bottom lance position is ≤500mm, replace the furnace bottom with a new one. The replacement furnace bottom should be constructed to a height h. i+1 It satisfies the following equation (1). （1） Where w is the converter charge (kg); ρ is the density of the molten steel; h i+1 h1 is the refractory design height for replacing the (i+1)th hearth in the converter, in mm; h1 is the refractory height of the first hearth, in mm; r1 is the radius at the converter height h1 position, in mm; r i+1 The height h of the (i+1)th furnace bottom refractory i+1 The average radius of the furnace at the location of the first furnace bottom, in mm; R1 is the radius of the furnace at height H inside the converter, in mm; R i+1 It is the average radius of the furnace at the (i+1)th furnace bottom height H position, in mm; where H is calculated by the following formula (2), （2）。

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