A method for improving the success rate of slagging in the early stage of a converter

Abstract

The application discloses a method for improving the success rate of early slagging of a converter, which comprises the following steps: step one, calculating the total blowing time based on smelting information; step two, determining the optimal slagging time range, and deriving the dry dedusting pressure range p1-p2 corresponding to the optimal slagging time range according to formula (1); and step three, monitoring the dry dedusting pressure during the smelting process, and stopping blowing and starting early slagging when the pressure is in the dry dedusting pressure range p1-p2. The method can be applied to the steelmaking process on a large scale, is simple to operate and stable in effect, can effectively control the timing of early slagging of the converter, can effectively improve the success rate of early slagging of the converter, can reduce the deviation in the steelmaking process, can effectively improve the terminal hitting rate of the converter, can improve the quality of products and social and economic benefits, and can provide technical support for efficient and low-cost production of the converter.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a method for improving the success rate of slag removal in the early stage of converter. Background Technology

[0002] Converter steelmaking is of paramount importance in steel plants today, representing the overall cost and process quality control level of the plant. Therefore, achieving low-cost, high-efficiency, and high-quality production in converters during modern steelmaking is a goal pursued by every steelmaking professional. In recent years, with the continuous advancement of steelmaking technology, numerous innovative processes have emerged in converter steelmaking, focusing on efficient dephosphorization and low consumption. Among these, low-slag smelting and slag retention with double-slag processes are widely adopted in an increasing number of steel plants. These processes all involve the crucial step of pre-converter slag removal, which has the following core significance in the steelmaking process: Phosphorus removal needs to be completed preferentially under low temperature and high basicity conditions. Pre-converter slag removal can promptly discharge the initial slag containing high phosphorus oxides, preventing phosphorus reversion after the temperature rises later. By adjusting the slag composition (such as rapidly increasing the CaO content), the formation of a high-basicity slag system can be accelerated, enhancing the efficiency of the initial dephosphorization reaction. In the initial stage of smelting, elements such as silicon and phosphorus in the molten iron oxidize to generate a large amount of acidic oxides. Timely slag dumping can prevent excessive slag accumulation and the risk of splashing, while also reducing the "re-drying" phenomenon caused by excessive slag in the middle stage, thus maintaining the stability of the smelting process. The newly generated slag after dumping can more effectively cover the surface of the molten steel, reducing radiative heat loss. At the same time, by controlling the slag layer thickness, the impact of oxygen flow and the dispersion effect of metal droplets are balanced, creating a favorable environment for subsequent decarburization and other reactions. However, in actual production, many factors affect the initial slag dumping, including molten iron composition, temperature, slag retention amount, smelting oxygen flow rate, and material addition. Each of these factors can affect the initial slag. The key to achieving efficient and low-cost converter smelting lies in how to accurately perform the initial slag dumping operation. Therefore, improving the success rate of initial slag dumping in converters is a common technical challenge in the steelmaking industry.

[0003] Patent CN201410233273.0 provides a method for controlling slag removal in the early stage of converter low-slag smelting. By controlling the lance position, oxygen supply intensity, and the amount of lime and iron ore added during the converter blowing desilication and dephosphorization periods, and utilizing slag foaming agent and weighing equipment on the steel slag jar, the method accurately controls the amount of slag removed in the early stage of the converter's "double slag + slag retention" smelting process, thus achieving the purpose of the converter's "double slag + slag retention" smelting process. Patent CN202111417698.3 provides a method for low-slag smelting with slag retention under converter dry dust removal process conditions. It monitors the CO concentration in the furnace using an audio slag monitoring system and performs lance operation based on the CO concentration curve; the lance position adopts constant lance pressure variation operation to balance the furnace temperature and carbon-oxygen reaction. By optimizing oxygen-enriched combustion and ignition gun positions, and avoiding explosions during initial blowing, targeted, systematic, and breakthrough optimizations of oxygen supply and slag-forming processes ensure coordinated and balanced control of "temperature, carbon-oxygen reaction, and FeO" at each stage. This avoids dry explosions while achieving cost reduction through low-slag smelting. Both of these methods control traditional converter operations and blowing processes that affect the initial slag formation, improving slag-forming efficiency and reducing slag discharge. All process optimizations originate from the converter itself. Therefore, considering all factors, these two methods are not the optimal choice.

[0004] In converter steelmaking, the formation and removal of the initial slag are influenced by process parameters such as molten iron conditions, the addition of raw materials and auxiliary materials, and oxygen flow rate. In actual operation, steelmaking personnel typically determine different slag removal time periods based on varying slag volume, molten iron silicon content, and temperature. They then manually observe the flame or use sonar systems to detect slag changes to pinpoint the optimal slag removal time. However, determining the correct slag removal time is challenging due to varying operator skill levels and system detection errors, resulting in a low success rate and impacting converter endpoint control and material consumption. Therefore, accurately predicting the timing of initial slag removal using smelting data and improving its success rate is a key technical challenge that needs to be addressed in the current steelmaking converter smelting field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for improving the success rate of early slag dumping in the converter by timely and effectively controlling the timing of early slag dumping.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention includes the following steps: Step 1, determining the total blowing time based on smelting information;

[0007] Step 2: Determine the optimal slag removal time range and derive the dry dust removal pressure range p1~p2 corresponding to the optimal slag removal time range according to formula (1);

[0008] p=0.05271t 2 -2.214t+7.9 (1)

[0009] Where t is the converter blowing time in seconds; p is the dry dust removal pressure in Pa; and 7.9 is a constant.

[0010] Step 3: Monitor the dry dust removal pressure during the smelting process. When the pressure is within the dry dust removal pressure range of p1 to p2, stop blowing and start dumping the initial slag.

[0011] Furthermore, in step two, the optimal slag removal time range is 1 / 5 to 2 / 9 of the total blowing time.

[0012] Furthermore, in step one, based on the original smelting information such as raw material information, equipment operating conditions, energy medium, and steel grade requirements, the total blowing time and material addition results are calculated by the secondary automated calculation model.

[0013] Furthermore, the converter is a 100-ton to 260-ton converter.

[0014] The beneficial effects of adopting the above technical solution are as follows: Compared with conventional methods that directly control the addition of materials and the blowing process in the early stage of the converter based on changes in the composition of molten iron, this method is difficult to operate, makes it hard to achieve precise control of the slag in the early stage, and thus affects the overall blowing effect of the converter, resulting in a large deviation between the endpoint control and the target. This invention takes a unique approach by monitoring the internal pressure of the dry dust removal equipment in the converter. The pressure of the dry dust removal equipment directly reflects the progress of the internal chemical reaction in the early stage of the converter, and is therefore the key to accurately grasping the timing of slag removal in the early stage.

[0015] This invention addresses the industry-wide technical challenge of low early-stage slag removal success rates in converters caused by operational deviations. It can be applied on a large scale in steelmaking processes, offering simple operation and stable results. Compared to traditional steelmaking processes, this invention allows for timely and effective control of the timing of early-stage slag removal in converters, significantly improving the success rate, reducing deviations in the steelmaking process, effectively increasing the converter endpoint hit rate, enhancing product quality and improving social and economic benefits. It provides technical support for efficient and low-cost converter production. Attached Figure Description

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0017] Figure 1 This is a schematic diagram showing the relationship between the blowing time and the dry dust removal pressure described in this invention. Detailed Implementation

[0018] In existing technologies, how to accurately predict the timing of early-stage slag removal using smelting data and improve the success rate of early-stage slag removal is a technical challenge that needs to be solved in the field of steelmaking converter smelting. The inventors abandoned traditional process approaches and focused on process innovation around various factors in the early-stage reaction of the converter. Through extensive experimental research, they discovered that by monitoring the pressure changes of the dry dust removal equipment and combining it with data from the secondary automated steelmaking process, the timing of early-stage slag removal can be accurately determined, thereby effectively improving the success rate of early-stage slag removal. After extensive field tests, it was found that there is a close relationship between converter blowing time and the pressure of the dry dust removal equipment, with the corresponding relationship as follows: Figure 1 As shown, by performing regression analysis on the experimental data, the mathematical relationship between the blowing time and the dry dust removal pressure described in this method for improving the success rate of slag removal in the early stage of the converter can be obtained:

[0019] p=0.05271t 2 -2.214t+7.9 (1)

[0020] Where t is the converter blowing time, in seconds;

[0021] p represents the dry dust removal pressure, which is the internal pressure of the dry dust removal equipment, and the unit is Pa.

[0022] 7.9 is a constant.

[0023] To further accurately grasp the timing of slag dumping in the early stage, a large amount of on-site data was collected, and the preliminary conclusion was that the best results can be obtained by controlling the slag dumping time between one-fifth and two-ninths of the total blowing time.

[0024] Therefore, based on the above conclusions, the method for improving the success rate of slag removal in the early stage of converter includes the following steps:

[0025] Step one: First, based on the original smelting information such as raw material information, equipment operating conditions, energy medium, and steel grade requirements, the total blowing time and material addition results are calculated by the secondary automated calculation model; the secondary automated calculation model can be a known calculation model.

[0026] Step 2: Determine the optimal slag removal time range t1~t2. The optimal slag removal time range is 1 / 5~2 / 9 of the total blowing time, that is, t1 is 1 / 5 of the total blowing time and t2 is 2 / 9 of the total blowing time. According to formula (1), the dry dust removal pressure range p1~p2 corresponding to the optimal slag removal time range is derived, that is, p1 is the dry dust removal pressure corresponding to t1 and p2 is the dry dust removal pressure corresponding to t2.

[0027] p=0.05271t 2 -2.214t+7.9 (1)

[0028] Where t is the converter blowing time in seconds; p is the dry dust removal pressure in Pa; and 7.9 is a constant.

[0029] When the dry dust removal pressure is within the range of p1 to p2, it indicates that it is within the optimal slag removal time range.

[0030] Because the blowing time range is wide and difficult to control, the dry dust removal pressure used in this method can effectively reflect the carbon-oxygen reaction in the furnace and more accurately determine the timing of slag removal. If we simply look at the blowing time, we cannot accurately achieve the removal of the early slag, because when the oxygen pressure in the converter is low, although the blowing time reaches the target range, the actual reaction in the furnace is slow and the early slag cannot be removed.

[0031] Step 3: Monitor the dry dust removal pressure during the smelting process. When the dry dust removal pressure is within the range of p1 to p2, stop blowing and start dumping the initial slag.

[0032] Example 1: The method for improving the success rate of slag removal in the early stage of converter is as follows.

[0033] Taking a 120-ton converter as an example, after calculation by the secondary automation model, the pressure range of the dry dust removal equipment can be calculated according to the different blowing times of different heats and the slag removal time selection and formula of this application, thereby determining the accurate slag removal time. In this embodiment, a total of 8 heats were smelted, and the specific results of each heat are shown in Table 1 below.

[0034] Table 1: Timing and Effects of Slag Removal in the Pre-Slag Removal Phase of a 120-ton Converter

[0035]

[0036] In Table 1, t1 is the start time of the optimal slag removal time range, which is 1 / 5 of the total blowing time; t2 is the end time of the optimal slag removal time range, which is 2 / 9 of the total blowing time; p1 is the dry dust removal pressure corresponding to the start time t1 of the optimal slag removal time range, and p2 is the dry dust removal pressure corresponding to the end time t2 of the optimal slag removal time range.

[0037] Example 2: The method for improving the success rate of slag removal in the early stage of converter is described in detail below.

[0038] Taking a 180-ton converter as an example, after calculation by the secondary automation model, the pressure range of the dry dust removal equipment can be calculated according to the different blowing times of different furnaces and the slag removal time selection and formula of this application, thereby determining the accurate slag removal time. In this embodiment, a total of 8 furnaces were smelted, and the specific results of each furnace are shown in Table 2 below.

[0039] Table 2: Timing and Effects of Slag Removal in the Pre-Slag Removal Phase of a 180-ton Converter

[0040]

[0041] Example 3: The method for improving the success rate of slag removal in the early stage of converter is described in detail below.

[0042] Taking a 260-ton converter as an example, after calculation by the secondary automation model, the pressure range of the dry dust removal equipment can be calculated according to the different blowing times of different heats and the slag removal time selection and formula of this application, thereby determining the accurate slag removal time. In this embodiment, a total of 8 heats were smelted, and the specific results of each heat are shown in Table 3 below.

[0043] Table 3: Timing and Effects of Slag Removal in the Pre-Slag Removal Phase of a 260-ton Converter

[0044]

[0045] Example 4: The specific method for improving the success rate of slag removal in the early stage of converter is as follows.

[0046] Taking a 100-ton converter as an example, after calculation by the secondary automation model, the pressure range of the dry dust removal equipment can be calculated according to the different blowing times of different heats and the slag removal time selection and formula of this application, thereby determining the accurate slag removal time. In this embodiment, a total of 8 heats were smelted, and the specific results of each heat are shown in Table 4 below.

[0047] Table 4: Timing and Effects of Slag Removal in the Early Stage of a 100-ton Converter

[0048]

[0049] Example 5: The specific method for improving the success rate of slag removal in the early stage of converter is as follows.

[0050] Taking a 120-ton converter as an example, after calculation by the secondary automation model, the pressure range of the dry dust removal equipment can be calculated according to the different blowing times of different heats and the slag removal time selection and formula of this application, thereby determining the accurate slag removal time. In this embodiment, a total of 8 heats were smelted, and the specific results of each heat are shown in Table 5 below.

[0051] Table 5: Timing and Effects of Slag Removal in the Pre-Slag Removal Phase of a 120-ton Converter

[0052]

[0053] Example 6: The specific method for improving the success rate of slag removal in the early stage of converter is as follows.

[0054] Taking a 180-ton converter as an example, after calculation by the secondary automation model, the pressure range of the dry dust removal equipment can be calculated according to the different blowing times of different heats and the slag removal time selection and formula of this application, thereby determining the accurate slag removal time. In this embodiment, a total of 8 heats were smelted, and the specific results of each heat are shown in Table 6 below.

[0055] Table 6: Timing and Effects of Slag Removal in the Early Stage of 180-ton Converter

[0056]

[0057] Example 7: The method for improving the success rate of slag removal in the early stage of converter is described in detail below.

[0058] Taking a 260-ton converter as an example, after calculation by the secondary automation model, the pressure range of the dry dust removal equipment can be calculated according to the different blowing times of different heats and the slag removal time selection and formula of this application, thereby determining the accurate slag removal time. In this embodiment, a total of 8 heats were smelted, and the specific results of each heat are shown in Table 7 below.

[0059] Table 7: Timing and Effects of Slag Removal in the Pre-Slag Removal Phase of a 260-ton Converter

[0060]

[0061] Example 8: The specific method for improving the success rate of slag removal in the early stage of converter is as follows.

[0062] Taking a 100-ton converter as an example, after calculation by the secondary automation model, the pressure range of the dry dust removal equipment can be calculated according to the different blowing times of different heats and the slag removal time selection and formula of this application, thereby determining the accurate slag removal time. In this embodiment, a total of 8 heats were smelted, and the specific results of each heat are shown in Table 8 below.

[0063] Table 8: Timing and Effects of Slag Removal in the Early Stage of a 100-ton Converter

[0064]

[0065] The results of the above embodiments show that determining the slag discharge time based on the pressure of the dry dust removal equipment is effective and provides a basis for precise control of the converter endpoint.

Claims

1. A method for improving the success rate of early slagging of a converter, characterized in that, It comprises the following steps: step one, based on smelting information, determining the total blowing time; Step two, determine the best time range of slagging, the best time range of slagging is 1 / 5~2 / 9 of the total blowing time, according to formula (1) to deduce the dry dedusting pressure range p1~p2 corresponding to the best time range of slagging; p = 0.05271t 2 -2.214t + 7.9 (1); Wherein, t is the blowing time of converter, unit is s;P is the dry dedusting pressure, unit is Pa;7.9 is a constant; Step three, monitoring the dry dedusting pressure in the smelting process, when the pressure is in the dry dedusting pressure range p1~p2, stop blowing, start to pour the early slag.

2. The method for improving the success rate of slagging in the early stage of a VOD according to claim 1, characterized in that: The step one, based on the raw material information, equipment working condition, energy medium, steel grade requirement original smelting information, calculate the total blowing time and material adding result by the secondary automation calculation model.

3. The method for improving the success rate of slagging in the early stage of a converter according to claim 1 or 2, characterized in that: The converter is 100 tons~260 tons converter.

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