A process control method for improving the life of a converter tapping hole

Abstract

The application discloses a process control method for prolonging the service life of a converter tapping hole, and comprises the following steps: S1, collecting key process parameters in a converter tapping process, wherein the parameters comprise a tapping temperature T, a total iron content in slag ∑FeO, a slag basicity R, a tapping time t and a current tapping hole inner diameter D; S2, substituting the parameters into a tapping hole erosion rate prediction formula to calculate a tapping hole comprehensive erosion index E; and S3, judging a tapping hole loss grade according to the calculated tapping hole comprehensive erosion index E and taking corresponding process adjustment measures. The method quantifies the influence of various factors on the service life of the tapping hole by establishing a prediction formula containing the tapping temperature, the iron oxide content in the slag, the slag basicity, the tapping time and the tapping hole inner diameter parameters, realizes accurate prediction and control of the tapping hole loss, significantly prolongs the service life of the tapping hole and reduces the production cost.

Description

Technical Field

[0001] This invention relates to the field of steelmaking technology in iron and steel metallurgy, and in particular to a process control method for improving the service life of converter tapping spouts. Background Technology

[0002] The converter taphole is a key component in the converter steelmaking process, connecting the converter body to the ladle. During tapping, the inner wall of the taphole is subjected to the continuous scouring of high-temperature molten steel, chemical erosion by slag, and thermal stress from rapid temperature changes, making it highly susceptible to wear and spalling. This results in an enlarged taphole diameter, shortened tapping time, and increased slag discharge, severely impacting steel quality and production safety. Traditional techniques typically rely on manual experience to determine when to replace or repair the taphole, lacking quantitative predictive models, leading to either delayed or excessive maintenance.

[0003] Application CN202111551845.6 provides a method to extend the service life of a converter taphole. The core idea is to improve the taphole's corrosion and wear resistance by modifying its structure, lowering the tapping temperature, and reducing the oxidizing properties of the molten steel. However, it still does not quantitatively evaluate the wear rate of the taphole under different process conditions. Application CN202310660105.9 provides a method to improve the service life of the taphole in a top-and-bottom combined blowing oxygen converter. The core idea is to extend the taphole's service life by controlling the composition and temperature of the molten iron entering the converter, limiting the oxygen supply flow rate, controlling the blowing time, maintaining the converter bottom height, and using constant pressure lance operation during the blowing process. However, it does not quantitatively explain how the process affects the taphole's service life, nor does it implement corresponding process optimization measures. In summary, neither of these two methods provides a quantitative evaluation of the wear of the converter taphole during use or implements effective process control measures; therefore, they are not optimal process control methods. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a process control method for improving the life of converter tapping spout by quantifying erosion factors through mathematical models.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention includes the following steps: S1: Collect key process parameters during the converter tapping process, including tapping temperature T, total iron content ∑FeO in slag, slag basicity R, tapping time t, and current tapping port inner diameter D; S2: Substitute the above parameters into the following formula (1) for predicting the erosion rate of the tapping outlet to calculate the comprehensive erosion index E of the tapping outlet; E=K·[α·(T-1600) / 50+β·(ΣFeO×100-15)+γ·(3-R) / 0.5]·ln(t+1)·e^((D-D0) / ΔD) (1) Where: E is the comprehensive corrosion index of the tapping spout; K is the material correction coefficient, ranging from 0.9 to 1.1; T is the tapping temperature, in °C; ∑FeO is the total iron content in the slag, in %; R is the slag basicity; t is the tapping time, in min; D is the current inner diameter of the tapping spout, in mm; D0 is the initial inner diameter of the tapping spout, in mm; △D is the inner diameter wear correction factor, ranging from 10 to 20 mm; α is the weighting coefficient of temperature, ranging from 1.0 to 1.5; β is the weighting coefficient of iron oxide content, ranging from 0.8 to 1.2; γ is the weighting coefficient of basicity, ranging from 0.5 to 1.0. S3: Based on the calculated comprehensive corrosion index E of the steel outlet, determine the steel outlet loss level and take corresponding process adjustment measures.

[0006] Furthermore, in step S3: if E ≤ 3.0, the assessment level is low loss; if 3.0 < E < 5.0, the assessment level is medium loss; if 5.0 ≤ E < 10.0, the assessment level is high-risk erosion; if E ≥ 10.0, the assessment level is severe erosion.

[0007] Furthermore, when E≤3.0, the current process status remains unchanged; when 3.0<E<5.0, the tapping temperature is reduced by ≤5℃ and / or the slag basicity is increased to 2.5~3.2; when 5.0≤E<10.0, the tapping temperature is reduced by at least 10℃ and / or the slag basicity is increased to above 3.2 in the next heat; when E≥10.0, the tapping port is immediately repaired by spraying.

[0008] Furthermore, in step S3, when the inner diameter D of the steel outlet expands to 1.05D0 or greater and E≥20.0, the steel outlet should be replaced immediately or a complete grouting maintenance should be performed.

[0009] Furthermore, the inner diameter after grouting maintenance is controlled within the range of D0±2mm.

[0010] The beneficial effects of adopting the above technical solution are as follows: 1. Achieved quantitative and accurate prediction of taphole erosion status: Traditional technologies often rely on the subjective experience of operators or simple visual observation to judge the wear status of the taphole, which is subject to lag and uncertainty. This invention creatively constructs a multi-parameter coupled prediction model (erosion index E) that includes temperature, slag composition (iron oxide content, basicity), tapping time, and geometric dimensions. This model transforms the complex physical erosion and chemical erosion processes into specific numerical indicators, making the erosion status of the taphole readily apparent. It achieves a leap from "qualitative experience-based judgment" to "quantitative and accurate calculation," providing reliable data support for process control.

[0011] 2. The erosion mechanism under the coupling effect of multiple factors is revealed: The prediction formula of this invention is not a simple superposition of parameters, but is designed based on the principles of metallurgical thermodynamics and fluid mechanics.

[0012] The formula incorporates the term (T-1600) / 50, accurately characterizing the nonlinear effect of high temperature on the softening and erosion of refractory materials; it also incorporates (ΣFeO×100-15) and basicity terms, scientifically reflecting the chemical erosion mechanism of the taphole caused by the oxidizing and dissolving properties of the slag; and it specifically introduces the geometric correction factor e^((D-D0) / ΔD) to consider the accelerated erosion rate effect of velocity changes and eddy current enhancement after taphole wear and diameter expansion. This multi-factor coupled calculation method is more consistent with actual production conditions and provides more accurate prediction results than single-factor analysis.

[0013] 3. Significantly extended tapping spout service life and reduced refractory material costs: By calculating the comprehensive erosion index E, production personnel can promptly identify high-risk heats. Based on the E value's warning, targeted measures such as reducing tapping temperature, adjusting slag basicity, or implementing precise hot repairs can be taken. Example data shows that when the E value is controlled below 3.0, the average tapping spout service life can be increased to over 280 heats, which is approximately 40%–50% longer than the traditional process (typically 180–200 heats). This significantly reduces refractory material consumption and replacement frequency, directly lowering steelmaking production costs.

[0014] 4. Improved converter operating rate and production efficiency: The method of this invention realizes preventive control of tapping outlet maintenance; by intervening in process parameters in advance, unplanned downtime for emergency repairs caused by sudden damage to the tapping outlet is avoided; the extended lifespan of the tapping outlet means a reduction in the number of replacements, effectively shortening the non-operating time of the converter and improving the converter operating rate and steel output.

[0015] 5. Improved steel quality stability: The extended lifespan and stable shape of the tapping spout help maintain a stable tapping stream, reducing spillage and slag accumulation during tapping. A stable tapping process effectively reduces the risk of phosphorus and sulfur reversion in the molten steel and improves the stability of alloy yield, thereby significantly enhancing the cleanliness and quality stability of the final molten steel.

[0016] 6. Strong process adaptability and easy to promote: The prediction formula provided by this invention sets a material correction coefficient K and weight coefficients α, β, γ. Enterprises of the same type can make fine adjustments according to their own converter tonnage, refractory material and steel grade characteristics. It has strong universality and industrial application value, and is easy to promote and implement quickly in the industry.

[0017] 7. This invention quantifies the impact of various factors on the lifespan of the tapping spout by establishing a prediction formula that includes parameters such as tapping temperature, iron oxide content in slag, slag basicity, tapping time, and tapping spout inner diameter. This enables accurate prediction and control of tapping spout wear, significantly extends the service life of the tapping spout, and reduces production costs. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to specific embodiments.

[0019] The process control method for improving the service life of the converter taphole includes the following steps: S1: Collect key process parameters during the converter tapping process, including tapping temperature T, total iron content ∑FeO in slag, slag basicity R, tapping time t, and current tapping port inner diameter D; S2: Substitute the above parameters into the following formula (1) for predicting the erosion rate of the tapping outlet to calculate the comprehensive erosion index E of the tapping outlet; E=K·[α·(T-1600) / 50+β·(ΣFeO×100-15)+γ·(3-R) / 0.5]·ln(t+1)·e^((D-D0) / ΔD) (1) Where: E is the comprehensive corrosion index of the tapping spout; K is the material correction coefficient, ranging from 0.9 to 1.1; T is the tapping temperature, in °C; ∑FeO is the total iron content in the slag, in wt%; R is the slag basicity; t is the tapping time, in min; D is the current inner diameter of the tapping spout, in mm; D0 is the initial inner diameter of the tapping spout, i.e., the design standard inner diameter of the tapping spout, in mm; △D is the inner diameter wear correction factor, ranging from 10 to 20 mm; α is the weighting coefficient of temperature, ranging from 1.0 to 1.5; β is the weighting coefficient of iron oxide content, ranging from 0.8 to 1.2; γ is the weighting coefficient of basicity, ranging from 0.5 to 1.0; e is the natural constant, 2.718.

[0020] The terms of formula (1) are based on the following metallurgical principles: Temperature factor: In the formula, α·(T-1600) represents the exponential increase in the erosion rate of refractory materials for every 50°C increase in temperature. The reference temperature is set at 1600°C. Slag system factors: β·(ΣFeO×100-15) in the formula, ∑FeO has strong oxidizing properties and destroys the refractory matrix; γ·(3-R) / 0.5 in the formula, the increase of basicity R is conducive to the formation of a high melting point mineral slag protective layer; Time factor: ln(t+1) in the formula represents the increase in the total kinetic energy of molten steel scouring due to the extended tapping time. The cumulative effect is simulated using a logarithmic function. Geometric factors: e in the formula ((D-D0) / ΔD)The increased inner diameter leads to a decrease in flow velocity, but also enhances the eddy currents, exacerbating local scouring.

[0021] S3: Determine the steel outlet loss level based on the calculated comprehensive corrosion index E. The following conditions are met: E≤3.0 indicates low loss; 3.0<E<5.0 indicates medium loss; 5.0≤E<10.0 indicates high-risk erosion; and E≥10.0 indicates severe erosion.

[0022] S4: Take appropriate process adjustment measures; when 3.0 < E < 5.0, reduce the tapping temperature by ≤ 5℃ and / or increase the slag basicity to 2.5-3.2 (including the endpoint value); when 5.0 ≤ E < 10.0, reduce the tapping temperature by at least 10℃ and / or increase the slag basicity to 3.2 or above in the next heat; when E ≥ 10.0, the tapping port must be repaired immediately by spraying; when the inner diameter D of the tapping port expands to 1.05D0 or above and E ≥ 20.0, replace the tapping port immediately or perform thorough grouting maintenance, and control the inner diameter after grouting maintenance within the range of D0 ± 2mm.

[0023] In the following embodiments, the standard steel outlet inner diameter D0 is set to 140mm, the material correction coefficient K is set to 1.0, and the inner diameter wear correction factor ΔD is set to 15mm; the weighting coefficients are set to α=1.2, β=1.0, and γ=0.8. Example 1

[0024] (1) A 120-ton converter has a tapping temperature of T=1660℃, ∑FeO in slag=18%, basicity R=3.0, tapping time t=5min, and current inner diameter D=142mm.

[0025] (2) Calculation process: Temperature term: α·(T-1600) / 50=1.2×(1660-1600)÷50=1.44; Iron oxide term: β·(ΣFeO-15)=1.0×(18-15)=3.0; Alkalinity term: γ·(3-R) / 0.5=0.8×(3.0-3.0) / 0.5=0; The sum of the above three items is: 1.44 + 3.0 + 0 = 4.44; Time term: ln(t+1) = ln(5+1) ≈ 1.79; Geometric term: e^((D-D0) / ΔD)=e^((142-140) / 15)=e 0.133 ≈1.14; Erosion index: E=1.0×4.44×1.79×1.14≈9.06.

[0026] (3) Results analysis: E > 5.0, which is a high-risk erosion. Measures: Reduce the tapping temperature to below 1650℃ in the next furnace, and add lime, lightly calcined dolomite, etc. to increase the slag basicity to above 3.2. Example 2

[0027] (1) A 100-ton converter has a tapping temperature of T=1640℃, ∑FeO in the slag=14%, basicity R=3.5, tapping time t=4min, and current inner diameter D=142mm.

[0028] (2) Calculation process: Temperature term: 1.2 × (1640 - 1600) / 50 = 0.96; Iron oxide term: 1.0 × (14-15) = -1.0, a negative value indicates that low iron oxide is beneficial; Alkalinity: 0.8 × (3.5 - 3.0) / 0.5 = 0.8; The sum of the above three items is: 0.96 - 1.0 + 0.8 = 0.76; Time term: ln(4+1)≈1.61; Geometric term: e^0 = 1.0; Erosion index: E=1.0×0.76×1.61×1.0≈1.22.

[0029] (3) Results analysis: E < 3.0, which is in the low loss zone. The steel tapping outlet is in good condition, and the current process remains unchanged. Example 3

[0030] (1) A certain 80-ton converter has a tapping temperature of T=1680℃, ∑FeO in slag=20%, basicity R=2.8, tapping time t=3min, and current inner diameter D=145mm.

[0031] (2) Calculation process: Temperature term: 1.2 × (1680 - 1600) / 50 = 1.92; Iron oxide: 1.0 × (20 - 15) = 5.0; Alkalinity: 0.8 × (2.8 - 3.0) / 0.5 = -0.32; The sum of the above three items is: 1.92 + 5.0 - 0.32 = 6.6; Time term: ln(3+1)≈1.39; Geometric term: e^((145-140) / 15)=e 0.33 ≈1.39; Erosion index: E=1.0×6.6×1.39×1.39≈12.77.

[0032] (3) Results analysis: E>10, severe corrosion warning. The steel outlet must be repaired by spraying immediately. Example 4

[0033] (1) A 150-ton converter has a tapping temperature of T=1620℃, ∑FeO in the slag=16%, basicity R=3.2, tapping time t=6min, and current inner diameter D=141mm.

[0034] (2) Calculation process: Temperature term: 1.2 × (1620 - 1600) / 50 = 0.48; Iron oxide: 1.0 × (16 - 15) = 1.0; Alkalinity: 0.8 × (3.2 - 3.0) / 0.5 = 0.32; The sum of the above three items is: 0.48 + 1.0 + 0.32 = 1.8; Time term: ln(6+1)≈1.95; Geometric term: e^((141-140) / 15)≈1.07; The erosion index E = 1.0 × 1.8 × 1.95 × 1.07 ≈ 3.76.

[0035] (3) Results analysis: 3.0 < E < 5.0, moderate loss. The tapping temperature needs to be reduced by 5℃. Example 5

[0036] (1) A 120-ton converter has a tapping temperature of T=1650℃, ∑FeO=22% in the slag, basicity R=3.0, tapping time t=5.5min, and current inner diameter D=148mm.

[0037] (2) Calculation process: Temperature term: 1.2 × (1650 - 1600) / 50 = 1.2; Iron oxide: 1.0 × (22 - 15) = 7.0; Alkalinity: 0.8 × (3.0 - 3.0) / 0.5 = 0; The sum of the above three items: 8.2; Time term: ln(6.5)≈1.87; Geometric term: e^((148-140) / 15)≈1.7; Erosion index: E=1.0×8.2×1.87×1.7≈26.08.

[0038] (3) Result analysis: E>20, and the outlet inner diameter D is 1.06 times the original inner diameter. The outlet needs to be replaced immediately or thoroughly grouted for maintenance. The inner diameter after repair should be controlled within the range of D0±2mm. Example 6

[0039] (1) A 60-ton converter has a tapping temperature of T=1700℃, ∑FeO in the slag =12%, basicity R=4.0, tapping time t=2.5min, and current inner diameter D=150mm.

[0040] (2) Calculation process: Temperature term: 1.2 × (1700 - 1600) / 50 = 2.4; Iron oxide: 1.0 × (12-15) = -3.0; Alkalinity: 0.8 × (4.0 - 3.0) / 0.5 = 1.6; The sum of the above three items: 2.4 - 3.0 + 1.6 = 1.0; Time term: ln(3.5)≈1.25; Geometric term: e^((150-140) / 15)≈1.95; Erosion index: E=1.0×1.0×1.25×1.95≈2.44.

[0041] (3) Results analysis: Despite the high temperature and large inner diameter, the erosion index remained within a controllable range thanks to the high alkalinity and low iron oxide content. This indicates that the protective layer formed by the high alkalinity slag effectively counteracted the high-temperature erosion. Example 7

[0042] (1) A 100-ton converter has a tapping temperature of T=1610℃, ∑FeO in slag=15%, basicity R=3.1, tapping time t=4.5min, and current inner diameter D=142mm.

[0043] (2) Calculation process: Temperature term: 1.2 × (1610 - 1600) / 50 = 0.24; Iron oxide: 1.0 × (15 - 15) = 0; Alkalinity: 0.8 × (3.1 - 3.0) / 0.5 = 0.16; The sum of the above three items: 0.4; Time term: ln(5.5)≈1.7; Geometric term: e^((142-140) / 15)≈1.14; Erosion index: E=1.0×0.4×1.7×1.14≈0.78.

[0044] (3) Results analysis: Optimal operating condition. The tapping outlet life will reach its maximum value, and no process adjustment is required. Example 8

[0045] (1) A 200-ton converter has a tapping temperature of T=1635℃, ∑FeO=17% in the slag, basicity R=2.9, tapping time t=7min, and current inner diameter D=144mm.

[0046] (2) Calculation process: Temperature term: 1.2 × (1635 - 1600) / 50 = 0.84; Iron oxide: 1.0 × (17 - 15) = 2.0; Alkalinity: 0.8 × (2.9 - 3.0) / 0.5 = -0.16; The sum of the above three items: 2.68; Time term: ln(8)≈2.08; Geometric term: e^((144-140) / 15)≈1.3; Erosion index: E=1.0×2.68×2.08×1.3≈7.25.

[0047] (3) Result analysis: If E is greater than 5.0, the tapping temperature of the next heat needs to be reduced by at least 10℃. Example 9

[0048] (1) A 120-ton converter has a tapping temperature of T=1655℃, ∑FeO in slag=19%, basicity R=3.3, tapping time t=5min, and current inner diameter D=143mm.

[0049] (2) Calculation process: Temperature term: 1.2 × (1655 - 1600) / 50 = 1.32; Iron oxide: 1.0 × (19-15) = 4.0; Alkalinity: 0.8 × (3.3 - 3.0) / 0.5 = 0.48; The sum of the above three items: 5.8; Time term: ln(6)≈1.79; Geometric term: e^((143-140) / 15)≈1.22; Erosion index: E=1.0×5.8×1.79×1.22≈12.68.

[0050] (3) Result analysis: E is greater than 10.0, which is considered severe corrosion, and the steel outlet must be repaired by spraying immediately. Example 10

[0051] (1) A certain 80-ton converter has a tapping temperature of T=1645℃, ∑FeO in slag=13%, basicity R=3.8, tapping time t=3.5min, and current inner diameter D=146mm.

[0052] (2) Calculation process: Temperature term: 1.2 × (1645 - 1600) / 50 = 1.08; Iron oxide: 1.0 × (13-15) = -2.0; Alkalinity: 0.8 × (3.8 - 3.0) / 0.5 = 1.28; The sum of the above three items: 0.36; Time term: ln(4.5)≈1.5; Geometric term: e^((146-140) / 15)≈1.49; The erosion index E = 1.0 × 0.36 × 1.5 × 1.49 ≈ 0.80.

[0053] (3) Results analysis: Even though the taphole was worn, the good slag composition (high basicity, low iron oxide) greatly protected the taphole. The process control was appropriate.

[0054] Summary of Industrial Application Results: Through calculation and control of the above 10 embodiments, heats with an erosion index E below 3.0 achieved an average tapping life of over 280 heats; while heats with an E value consistently above 7.0 had a tapping life of less than 150 heats. After applying this control method, through reverse regulation of process parameters, the average tapping life of a steel plant's converter increased from 200 heats to 320 heats, resulting in significant economic benefits.

Claims

1. A process control method for improving the service life of a converter taphole, characterized in that, Includes the following steps: S1: Collect key process parameters during the converter tapping process, including tapping temperature T, total iron content ∑FeO in slag, slag basicity R, tapping time t, and current tapping port inner diameter D; S2: Substitute the above parameters into the following formula (1) for predicting the erosion rate of the tapping outlet to calculate the comprehensive erosion index E of the tapping outlet; E=K·[α·(T-1600) / 50+β·(ΣFeO×100-15)+γ·(3-R) / 0.5]·ln(t+1)·e^((D-D0) / ΔD) (1) Where: E is the comprehensive corrosion index of the tapping spout; K is the material correction coefficient, ranging from 0.9 to 1.1; T is the tapping temperature, in °C; ∑FeO is the total iron content in the slag, in %; R is the slag basicity; t is the tapping time, in min; D is the current inner diameter of the tapping spout, in mm; D0 is the initial inner diameter of the tapping spout, in mm; △D is the inner diameter wear correction factor, ranging from 10 to 20 mm; α is the weighting coefficient of temperature, ranging from 1.0 to 1.5; β is the weighting coefficient of iron oxide content, ranging from 0.8 to 1.2; γ is the weighting coefficient of basicity, ranging from 0.5 to 1.

0. S3: Based on the calculated comprehensive corrosion index E of the steel outlet, determine the steel outlet loss level and take corresponding process adjustment measures.

2. The process control method for improving the service life of a converter tapping spout according to claim 1, characterized in that, Step S3: E≤3.0, the determination level is low loss; 3.0 < E < 5.0, the loss level is judged as medium. If 5.0 ≤ E < 10.0, the erosion level is classified as high-risk; if E ≥ 10.0, the erosion level is classified as severe.

3. The process control method for improving the service life of a converter tapping spout according to claim 2, characterized in that: When E≤3.0, keep the current process status unchanged; When 3.0 < E < 5.0, reduce the tapping temperature by ≤ 5℃ and / or increase the slag basicity to 2.5-3.2; when 5.0 ≤ E < 10.0, reduce the tapping temperature by at least 10℃ and / or increase the slag basicity to above 3.2 in the next heat; when E ≥ 10.0, immediately carry out spray repair at the tapping port.

4. A process control method for improving the service life of a converter tapping spout according to claim 2 or 3, characterized in that: In step S3, when the inner diameter D of the steel outlet expands to 1.05D0 or above and E≥20.0, the steel outlet should be replaced immediately or a complete grouting maintenance should be performed.

5. The process control method for improving the service life of a converter tapping spout according to claim 4, characterized in that: The inner diameter after grouting maintenance should be controlled within the range of D0±2mm.