A low cost rh treatment process

Abstract

The present application relates to the technical field of RH production, and particularly relates to a low-cost RH treatment process. According to different H-increasing degrees, the present application divides the number of continuous casting and continuous casting furnaces and the baking temperature of tundish, divides the RH treatment process according to different H-removing degrees, and adopts different grading RH treatment processes (different treatment time, different vacuum degree and different lifting gas flow) for different zoning combinations, so as to meet the demand of low-cost control of final tundish H≤2.5ppm, and solve the problem of high cost caused by the fixed long treatment time, low vacuum degree and large lifting gas flow of the conventional RH treatment process. The present application is suitable for the steel grade produced by low-cost RH treatment, and can realize cost reduction of more than 38 yuan / ton of steel.

Description

Technical Field

[0001] This invention relates to the field of steelmaking production technology, and in particular to a low-cost RH treatment process. Background Technology

[0002] For the RH process, whose main function is to remove hydrogen (H) content from molten steel, the conventional approach involves fixed RH treatment time, fixed RH vacuum level, and fixed RH booster gas flow rate. While this method is relatively simple, it suffers from cost waste and quality overload, resulting in high production costs. In today's highly competitive steel industry, it lacks a manufacturing advantage. Therefore, finding a low-cost RH treatment method to obtain molten steel with the required H content in the tundish has become crucial for enhancing a company's competitiveness.

[0003] However, practical experience has shown that the RH process, the number of consecutive casting heats, and the tundish baking temperature have a significant impact on the H content in the molten steel. The typical RH treatment time is 3 to 60 minutes; the typical vacuum level is 20 Pa to 8000 Pa; and the typical circulation flow rate is 30 Nm³. 3 / h~200Nm 3 The combination of these three processes (RH treatment time, vacuum level, and circulation flow rate) significantly impacts the RH dehydrogenation effect. Longer RH treatment times, lower vacuum levels, and higher circulation flow rates result in better RH dehydrogenation, but also higher costs. The number of consecutive casting heats also significantly affects the degree of hydrogen gain during continuous casting. Typically, the number of consecutive heats can range from one to dozens, with earlier heats resulting in greater hydrogen gain. Different baking temperatures for the tundish also greatly influence the hydrogen gain outcome, typically ranging from 1000 to 1300°C. Lower baking temperatures lead to more pronounced hydrogen gain in the tundish but also reduce gas consumption and costs. Therefore, achieving the optimal combination of low-cost RH dehydrogenation and continuous casting hydrogen gain is difficult. Summary of the Invention

[0004] To address the shortcomings of existing methods, this invention optimizes the RH cost for over-RH treated steel grades. By considering the number of continuous casting heats and the tundish baking temperature, a graded RH process is adopted to meet the requirement of H content ≤ 2.5 ppm in the tundish. By tracking the H increase in molten steel under different numbers of continuous casting heats and different tundish baking temperatures, and considering the dehydrogenation capacity under different RH treatment times, vacuum levels, and booster gas flow rates, the H content in the molten steel in the tundish can ultimately be controlled to ≤ 2.5 ppm. This solution, through graded RH process management, reduces RH treatment costs compared to the traditional directly fixed RH treatment process. Furthermore, based on the dehydrogenation capacity under the graded RH process and the H increase under different numbers of continuous casting heats and different tundish baking temperatures, it ensures that the H content in the molten steel in the tundish meets the requirements. It is suitable for low-cost production of over-RH steel grades.

[0005] The technical solution adopted in this invention is: a low-cost RH treatment process, which implements different RH treatment processes according to the tundish baking temperature and the number of continuous casting furnaces: T1+S1 is RH-AAA process, T1+S2 is RH-AA process, T1+S3 is RH-A process, T1+S4 is RH-B process; T2+S1 is RH-AA process, T2+S2 is RH-A process, T2+S3 is RH-B process; T3+S1 is RH-A process, T3+S2 is RH-B process; the rest are RH-C process;

[0006] Furthermore, T1 to T3 are the baking temperature zones for the continuous casting tundish, namely T1: 1000℃~1100℃, T2: 1100℃~1200℃, and T3: 1200℃~1300℃.

[0007] Furthermore, S1 to S5 are the number of zones for continuous casting and pouring furnaces, where S1 is the first furnace poured, S2 is the second furnace poured, S3 is the third furnace poured, S4 is the fourth to sixth furnace poured, and S5 is the seventh furnace poured.

[0008] Furthermore, the RH-AAA process has a processing time of 15 minutes, a vacuum degree of 32 Pa, and a circulation flow rate of 130 Nm³. 3 / h; the RH-AA process has a processing time of 15 min, a vacuum degree of 6000 Pa, and a circulation flow rate of 130 Nm³. 3 / h; the RH-A process has a processing time of 8 minutes, a vacuum degree of 800 Pa, and a circulation flow rate of 130 Nm³. 3 / h; the RH-B process has a processing time of 8 minutes, a vacuum degree of 6000 Pa, and a circulation flow rate of 75 Nm³. 3 / h; the RH-C process has a processing time of 5 min, a vacuum degree of 6000 Pa, and a circulation flow rate of 75 Nm³. 3 / h.

[0009] Furthermore, the H content of the intermediate package is ≤2.5ppm.

[0010] The tundish baking temperatures for continuous casting are divided into three levels: T1 (1000℃~1100℃), T2 (1100℃~1200℃), and T3 (1200℃~1300℃). This is because the main purpose of tundish baking is to remove moisture from the tundish coating and simultaneously raise the temperature of the refractory material itself to prevent cracking upon contact with the high-temperature (approximately 1550℃) molten steel. Currently, considering the tundish baking schedule, the conventional tundish baking temperature range is 1000℃~1300℃. Temperatures below 1000℃ are unfavorable for continuous casting start-up (too low a temperature makes the molten steel prone to solidification upon contact with the refractory material); temperatures above 1300℃ can easily lead to decarburization of the refractory material, making its lifespan uncontrollable. Different temperature ranges in the tundish (1000℃~1100℃, 1100℃~1200℃, 1200℃~1300℃) have different effects on the increase of hydrogen in molten steel. The lower the temperature, the greater the increase of hydrogen in molten steel.

[0011] The continuous casting heat number is divided into S1 to S5, namely S1: the first heat, S2: the second heat, S3: the third heat, S4: the fourth to sixth heats, and S5: the seventh heat or higher. This is because the increase in hydrogen (H) in the molten steel in the tundish varies depending on the number of heats. The first heat has the highest H increase, which decreases with each subsequent heat, eventually stabilizing after a certain number of heats. A smaller H increase during continuous casting allows for a lower RH (residue and hygroscopicity) removal requirement, ultimately reducing production costs.

[0012] The RH treatment process is classified into five categories: RH-AAA, RH-AA, RH-A, RH-B, and RH-C. This classification is designed to reduce production costs. The RH-AAA process has the longest RH vacuum treatment time, the lowest RH vacuum level, and the highest RH boost gas flow rate, resulting in the strongest H removal capability, with the final H level controllable to ≤0.3ppm. The RH-C process has the shortest RH vacuum treatment time, the highest RH vacuum level, and the lowest RH boost gas flow rate, resulting in the weakest H removal capability, with the final H level controllable to ≤2.4ppm.

[0013] The reason for requiring T1+S1 to be RH-AAA process, T1+S2 to be RH-AA process, T1+S3 to be RH-A process, and T1+S4 to be RH-B process; T2+S1 to be RH-AA process, T2+S2 to be RH-A process, and T2+S3 to be RH-B process; T3+S1 to be RH-A process and T3+S2 to be RH-B process; and the rest to be RH-C process, is as follows:

[0014] Experiments have shown that the higher the tundish baking temperature and the greater the number of consecutive casting heats, the smaller the increase in RH in the tundish. Based on extensive experiments, this invention has determined that different tundish baking temperatures, combined with the continuous casting sequence number, correspond to different RH grading processes, achieving low-cost production.

[0015] ①The T1+S1 intermediate package increases H by about 2ppm. To ensure that the final H in the intermediate package is ≤2.5ppm, it is necessary to use the RH-AAA process (RH endpoint H ≤0.3ppm), and finally the final H in the intermediate package is ≤2.3ppm.

[0016] ②The intermediate packages T1+S2 and T2+S1 increase the H by about 1.5ppm. In order to ensure that the H in the intermediate package is ≤2.5ppm and the cost is the lowest, it is necessary to use the RH-AA process (RH endpoint H ≤0.9ppm) to finally achieve a H of ≤2.4ppm in the intermediate package.

[0017] ③The intermediate packages T1+S3, T2+S2, and T3+S1 increase the H content by approximately 1.0 ppm. To ensure that the final H content of the intermediate package is ≤2.5 ppm and the cost is minimized, it is necessary to use the RH-A process (RH endpoint H ≤1.4 ppm) to achieve a final H content of ≤2.4 ppm in the intermediate package.

[0018] ④ The intermediate packages T1+S4, T2+S3, and T3+S2 increase the hydrogen content by about 0.5ppm. To ensure that the final hydrogen content of the intermediate package is ≤2.5ppm and the cost is minimized, it is necessary to use the RH-B process (RH endpoint hydrogen content ≤1.9ppm) to achieve a final hydrogen content of ≤2.4ppm in the intermediate package.

[0019] ⑤ Under other conditions, the H content in the intermediate package is approximately 0 ppm. To ensure that the H content in the intermediate package is ≤2.5 ppm and the cost is minimized, the RH-C process is used (RH endpoint H ≤2.4 ppm), resulting in a final H content in the intermediate package of ≤2.4 ppm.

[0020] The requirement of ≤2.5ppm H content in the tundish is due to the different requirements for different steel grades during the RH process. For high-requirement steel grades, the purpose of RH treatment is not only to remove H, but also to remove inclusions using the RH cycle. Therefore, higher requirements are placed on RH treatment time and vacuum level. For ordinary steel grades, the main purpose of RH treatment is H removal, with no special requirements for inclusions. Usually, a ≤2.5ppm H content in the continuous casting tundish is sufficient. Excessive H content can cause "white spot" defects in the core of the product. Therefore, a H content of ≤2.5ppm in the molten steel in the tundish is generally required to meet the requirement.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention combines the different degrees of H content increase in molten steel and the degree of H removal in the graded RH treatment process with the number of continuous casting furnaces and the tundish baking temperature zones. Different graded RH treatment processes are adopted for different zone combinations, which reduces production costs while ensuring the H content requirements of molten steel in the tundish.

[0023] 2. Compared with traditional RH-treated steel grades, the present invention can reduce costs by more than 38 yuan / ton of steel. Attached image description:

[0024] Figure 1 Schematic diagram of the RH treatment process of the present invention;

[0025] Figure 2 Cost comparison chart of embodiments and comparative examples of the present invention. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments. The drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0027] like Figure 1 As shown, a low-cost RH treatment process includes the following steps:

[0028] (1) Taking the production of 20G steel as an example, the production process is BOF-LF-RH-CCM, the cross section is 220*260, the number of consecutive casting furnaces is 12 heats as one casting cycle, and the weight of each heat of steel is about 120t.

[0029] The composition range of 20G steel is as follows: C: 0.17%~0.23%, Si: 0.17%~0.37%, Mn: 0.35%~0.36%, P: ≤0.025%, S: ≤0.015%, Cr: ≤0.25%, Cu: ≤0.20%, Mo: ≤0.15%, Al: ≤0.015%, with the remainder being Fe and unavoidable impurities.

[0030] BOF: 120t BOF furnace, approximately 100t of molten iron and 30t of scrap steel are added, oxygen supply time is approximately 12 minutes, oxygen supply pressure is approximately 0.76MPa, and oxygen consumption is approximately 6400m³. 3 Add approximately 3500 kg of lime, approximately 1400 kg of calcium ferrite, approximately 250 kg of limestone, and the tapping temperature is approximately 1600℃. During the tapping process, add approximately 480 kg of ferrosilicon, approximately 100 kg of ferrosilicon, approximately 130 kg of aluminum blocks, approximately 50 kg of nitrogen-carbonizing agent, approximately 230 kg of refining slag, and approximately 500 kg of lime.

[0031] LF: Inlet temperature approximately 1530℃, total energization time approximately 40 minutes, total smelting time approximately 80 minutes, addition of approximately 600 kg of ferrosilicon, approximately 200 kg of ferrosilicon, approximately 100 kg of carbon raiser, approximately 200 kg of silicon carbide, and approximately 20 kg of aluminum granules. Ladle temperature approximately 1645℃.

[0032] RH: The inlet temperature is about 1640℃, and the temperature after soft blowing is about 1600℃. The type of boosting gas is Ar. No alloys are added during the process. Only Ca treatment is performed after the process. The amount of Ca treatment is about 150m of silicon-calcium wire.

[0033] CCM: The ladle temperature at the casting platform is approximately 1590℃, the secondary cooling water volume for continuous casting is 0.4L / kg, and the casting speed is approximately 1.2m / min.

[0034] (2) Prepare intermediate breads for three types of intermediate bread baking temperatures, corresponding to the baking temperatures of the intermediate breads as follows: 1000℃~1100℃ (actual measured 1052℃, 1054℃, 1053℃), 1100℃~1200℃ (actual measured 1171℃, 1170℃), and 1200℃~1300℃ (actual measured 1288℃, 1289℃, 1286℃).

[0035] The higher the baking temperature of the tundish, the greater the amount of gas consumed and the higher the cost. According to cost calculations, T1: 1000℃~1100℃ corresponds to a cost of 3.8 yuan / ton of steel, T2: 1100℃~1200℃ corresponds to a cost of 4.3 yuan / ton of steel, and T3: 1200℃~1300℃ corresponds to a cost of 5.1 yuan / ton of steel.

[0036] (3) RH grading process cost.

[0037] The longer the RH vacuum treatment time, the lower the RH vacuum degree, and the larger the RH circulation flow rate, the higher the RH cost. The RH-AAA process corresponds to an RH cost of 85 yuan / ton of steel, the RH-AA process corresponds to an RH cost of 72 yuan / ton of steel, the RH-A process corresponds to an RH cost of 63 yuan / ton of steel, the RH-B process corresponds to an RH cost of 52 yuan / ton of steel, and the RH-C process corresponds to an RH cost of 31 yuan / ton of steel.

[0038] (4) Conduct example and comparative experiments; track the H determination results of intermediate package.

[0039] (5) Calculate the cost of the entire process.

[0040] Example 1:

[0041] This corresponds to an intermediate bread baked at 1052℃.

[0042] The first furnace was treated using the RH-AAA process, and the H content after RH treatment was 0.3 ppm.

[0043] The second furnace was treated using the RH-AA process, and the H content after the RH treatment was 0.8 ppm.

[0044] The third furnace was treated using the RH-A process, and the final H content after RH treatment was 1.2 ppm.

[0045] Furnaces 4 through 6 were treated using the RH-B process, and the final H concentrations after RH treatment were 1.8 ppm to 1.9 ppm, respectively.

[0046] Furnaces 7 through 12 were treated using the RH-C process, and the final H concentration after RH treatment was 2.2 ppm to 2.4 ppm.

[0047] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0048] The first batch was poured continuously, and the H content in the tundish was set at 2.3 ppm.

[0049] The second batch was poured, and the H content in the tundish was set at 2.2 ppm.

[0050] The third batch was poured, and the H content in the tundish was set at 2.3 ppm.

[0051] For the 4th to 6th consecutive heats, the H content in the tundish was set at 2.3 ppm to 2.4 ppm.

[0052] For the 7th to 12th batches, the H content in the tundish was set at 2.2 ppm to 2.4 ppm.

[0053] Example 2:

[0054] This corresponds to an intermediate bread baked at a temperature of 1171℃.

[0055] The first furnace was treated using the RH-AA process, and the H content after the RH treatment was 0.9 ppm.

[0056] The second furnace was treated using the RH-A process, and the final H content after RH treatment was 1.4 ppm.

[0057] The third furnace was treated using the RH-B process, and the final H content after RH treatment was 1.9 ppm.

[0058] Furnaces 4 through 12 were treated using the RH-C process, and the final H concentrations after RH treatment were 2.2 ppm to 2.4 ppm, respectively.

[0059] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0060] The first batch was poured continuously, and the H content in the tundish was set at 2.5 ppm.

[0061] The second batch was poured, and the H content in the tundish was set at 2.3 ppm.

[0062] The third batch was poured, and the H content in the tundish was set at 2.4 ppm.

[0063] For the 4th to 12th batches, the H content in the tundish was set at 2.2 ppm to 2.4 ppm.

[0064] Example 3:

[0065] This corresponds to an intermediate bread baked at 1288℃.

[0066] The first furnace was treated using the RH-A process, and the final H content after RH treatment was 1.3 ppm.

[0067] The second furnace was treated using the RH-B process, and the final H concentration after RH treatment was 1.7 ppm.

[0068] Heats 3 through 12 were treated using the RH-C process, with a final H concentration of 2.3 ppm to 2.4 ppm after RH treatment. Corresponding to the H concentration results in the tundish during continuous casting:

[0069] The first batch was poured continuously, and the H content in the tundish was set at 2.4 ppm.

[0070] The second batch was poured, and the H content in the tundish was set at 2.3 ppm.

[0071] For the 3rd to 12th batches, the H content in the tundish was set at 2.3 ppm to 2.4 ppm.

[0072] Comparative Example 1:

[0073] This corresponds to an intermediate bread baked at a temperature of 1054℃.

[0074] Heats 1-12 were treated using the RH-AAA process, with H concentrations at the end of RH treatment ranging from 0.2ppm to 0.3ppm. Corresponding to continuous casting and pouring, the H concentration results in the tundish were as follows:

[0075] For the first to 12th batches, the H content in the tundish was set at 0.2 ppm to 2.2 ppm.

[0076] Comparative Example 2:

[0077] This corresponds to an intermediate bread baked at 1170℃.

[0078] Heats 1-12 were treated using the RH-AAA process, with H concentrations at the end of RH treatment ranging from 0.2ppm to 0.3ppm. Corresponding to continuous casting and pouring, the H concentration results in the tundish were as follows:

[0079] For the first to 12th batches, the H content in the tundish was set at 0.2ppm to 1.7ppm.

[0080] Comparative Example 3:

[0081] This corresponds to an intermediate bread baked at a temperature of 1289℃.

[0082] Heats 1-12 were treated using the RH-AAA process, with final H concentrations of 0.1ppm-0.3ppm after RH treatment. Corresponding to continuous casting and pouring, the H concentration results in the tundish were as follows:

[0083] For the first to 12th batches, the H content in the tundish was set at 0.1ppm to 1.3ppm.

[0084] Comparative Example 4:

[0085] This corresponds to an intermediate bread baked at a temperature of 1286℃.

[0086] Furnaces 1 through 12 were treated using the RH-AA process, and the final H concentration after RH treatment was 0.8 ppm to 0.9 ppm.

[0087] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0088] For the first to 12th batches, the H content in the tundish was set at 0.8 ppm to 1.9 ppm.

[0089] Comparative Example 5:

[0090] This corresponds to an intermediate bread baked at 1053℃.

[0091] Furnaces 1 through 12 were treated using the RH-C process, and the final H concentration after RH treatment was 2.2 ppm to 2.4 ppm.

[0092] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0093] For the first 12 heats, the hydrogen content in the tundish should be set at 2.2ppm to 4.4ppm. (If the hydrogen content in the tundish exceeds the requirement of 2.5ppm, the steel will not meet the quality requirements).

[0094] Comparative Example 6:

[0095] This corresponds to an intermediate bread baked at 1052℃.

[0096] The first furnace was treated using the RH-AA process, and the H content after the RH treatment was 0.9 ppm.

[0097] The second furnace was treated using the RH-A process, and the final H content after RH treatment was 1.4 ppm.

[0098] The third furnace was treated using the RH-B process, and the final H content after RH treatment was 1.9 ppm.

[0099] Furnaces 4 through 12 were treated using the RH-C process, and the final H concentrations after RH treatment were 2.2 ppm to 2.4 ppm, respectively.

[0100] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0101] The first batch of tundish was poured consecutively, and the hydrogen concentration (H) in the intermediate ladle was 2.9 ppm (exceeding the standard).

[0102] The second batch was poured, and the hydrogen concentration in the tundish was 2.8 ppm (exceeding the limit).

[0103] The third batch was poured, and the hydrogen concentration in the tundish was 2.9 ppm (exceeding the limit).

[0104] For the 4th to 12th batches, the hydrogen concentration in the tundish was set at 2.2 ppm to 2.9 ppm. (H concentration exceeded the standard)

[0105] Comparative Example 7:

[0106] This corresponds to an intermediate bread baked at a temperature of 1054℃.

[0107] The first furnace was treated using the RH-A process, and the final H content after RH treatment was 1.3 ppm.

[0108] The second furnace was treated using the RH-B process, and the final H concentration after RH treatment was 1.7 ppm.

[0109] Furnaces 3 to 12 were treated using the RH-C process, and the final H concentration after RH treatment was 2.3 ppm to 2.4 ppm.

[0110] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0111] The first batch of tundish was poured, and the hydrogen concentration (H) in the intermediate ladle was 3.3 ppm (exceeding the standard).

[0112] The second batch was poured, and the hydrogen concentration in the tundish was 3.3 ppm (exceeding the limit).

[0113] For the 3rd to 12th batches, the hydrogen concentration in the tundish was set at 2.3 ppm to 3.4 ppm. (H concentration exceeded the standard)

[0114] Comparative Example 8:

[0115] This corresponds to an intermediate bread baked at a temperature of 1171℃.

[0116] The first furnace was treated using the RH-AAA process, and the H content after RH treatment was 0.3 ppm.

[0117] The second furnace was treated using the RH-AA process, and the H content after the RH treatment was 0.8 ppm.

[0118] The third furnace was treated using the RH-A process, and the final H content after RH treatment was 1.2 ppm.

[0119] Furnaces 4 through 6 were treated using the RH-B process, and the final H concentrations after RH treatment were 1.8 ppm to 1.9 ppm, respectively.

[0120] Furnaces 7 through 12 were treated using the RH-C process, and the final H concentration after RH treatment was 2.2 ppm to 2.4 ppm.

[0121] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0122] The first batch was poured continuously, and the H content in the tundish was set at 1.8 ppm.

[0123] The second batch was poured, and the H content in the tundish was set at 1.8 ppm.

[0124] The third batch was poured, and the H content in the tundish was set at 1.7 ppm.

[0125] For the 4th to 6th consecutive heats, the H content in the tundish was set at 1.8 ppm to 1.9 ppm.

[0126] For the 7th to 12th batches, the H content in the tundish was set at 2.2 ppm to 2.4 ppm.

[0127] Comparative Example 9:

[0128] This corresponds to an intermediate bread baked at 1170℃.

[0129] The first furnace was treated using the RH-A process, and the final H content after RH treatment was 1.3 ppm.

[0130] The second furnace was treated using the RH-B process, and the final H concentration after RH treatment was 1.7 ppm.

[0131] Furnaces 3 to 12 were treated using the RH-C process, and the final H concentration after RH treatment was 2.3 ppm to 2.4 ppm.

[0132] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0133] The first batch of tundish was poured consecutively, and the hydrogen concentration (H) in the intermediate ladle was 2.8 ppm (exceeding the standard).

[0134] The second batch was poured, and the hydrogen concentration in the tundish was 2.7 ppm (exceeding the limit).

[0135] For the 3rd to 12th batches, the hydrogen concentration in the tundish was set at 2.3 ppm to 2.9 ppm. (H exceeded the standard)

[0136] Comparative Example 10:

[0137] This corresponds to an intermediate bread baked at a temperature of 1289℃.

[0138] The first furnace was treated using the RH-AAA process, and the H content after RH treatment was 0.3 ppm.

[0139] The second furnace was treated using the RH-AA process, and the H content after the RH treatment was 0.8 ppm.

[0140] The third furnace was treated using the RH-A process, and the final H content after RH treatment was 1.2 ppm.

[0141] Furnaces 4 through 6 were treated using the RH-B process, and the final H concentrations after RH treatment were 1.8 ppm to 1.9 ppm, respectively.

[0142] Furnaces 7 through 12 were treated using the RH-C process, and the final H concentration after RH treatment was 2.2 ppm to 2.4 ppm.

[0143] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0144] The first batch was poured continuously, and the H content in the tundish was set at 1.3 ppm.

[0145] The second batch was poured, and the H content in the tundish was set at 1.3 ppm.

[0146] The third batch was poured, and the H content in the tundish was set at 1.2 ppm.

[0147] For the 4th to 6th consecutive heats, the H content in the tundish was set at 1.8 ppm to 1.9 ppm.

[0148] For the 7th to 12th batches, the H content in the tundish was set at 2.2 ppm to 2.4 ppm.

[0149] Comparative Example 11:

[0150] This corresponds to an intermediate bread baked at a temperature of 1286℃.

[0151] The first furnace was treated using the RH-AA process, and the H content after the RH treatment was 0.9 ppm.

[0152] The second furnace was treated using the RH-A process, and the final H content after RH treatment was 1.4 ppm.

[0153] The third furnace was treated using the RH-B process, and the final H content after RH treatment was 1.9 ppm.

[0154] Furnaces 4 through 12 were treated using the RH-C process, and the final H concentrations after RH treatment were 2.2 ppm to 2.4 ppm, respectively.

[0155] Corresponding to continuous casting and pouring, the tundish settling result is as follows:

[0156] The first batch was poured continuously, and the H content in the tundish was set at 1.9 ppm.

[0157] The second batch was poured, and the H content in the tundish was set at 1.9 ppm.

[0158] The third batch was poured, and the H content in the tundish was set at 1.9 ppm.

[0159] For the 4th to 12th batches, the H content in the tundish was set at 2.2 ppm to 2.4 ppm.

[0160] Cost Analysis

[0161] Example 1: The tundish baking temperature is 1052℃, with 12 consecutive heats. The gas consumption cost is 3.8 yuan / ton of steel. The RH cost for the first heat is 85 yuan / ton of steel, the RH cost for the second heat is 72 yuan / ton of steel, the RH cost for the third heat is 63 yuan / ton of steel, the RH cost for the fourth to sixth heats is 52 yuan / ton of steel, and the RH cost for the seventh to twelfth heats is 31 yuan / ton of steel. The corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 3.8 yuan / ton) + (1 heat * 85 yuan / ton * 120 tons / heater + 1 heat * 72 yuan / ton * 120 tons / heater + 1 heat * 63 yuan / ton * 120 tons / heater + 3 heats * 52 yuan / ton * 120 tons / heater + 6 heats * 31 yuan / ton * 120 tons / heater) = 5472 yuan + 67440 yuan = 72912 yuan.

[0162] Example 2: The tundish baking temperature was 1171℃, with 12 consecutive heats cast. The gas consumption cost was 4.3 yuan / ton of steel. The RH cost for the first heat was 72 yuan / ton of steel, the RH cost for the second heat was 63 yuan / ton of steel, the RH cost for the third heat was 52 yuan / ton of steel, and the RH cost for the fourth to twelfth heats was 31 yuan / ton of steel. The corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 4.3 yuan / ton) + (1 heat * 72 yuan / ton * 120 tons / heater + 1 heat * 63 yuan / ton * 120 tons / heater + 1 heat * 52 yuan / ton * 120 tons / heater + 9 heats * 31 yuan / ton * 120 tons / heater) = 6192 yuan + 55920 yuan = 62112 yuan.

[0163] Example 3: The tundish baking temperature was 1288℃, with 12 consecutive heats. The gas consumption cost was 5.1 yuan / ton of steel. The RH cost for the first heat was 63 yuan / ton of steel, the RH cost for the second heat was 52 yuan / ton of steel, and the RH cost for the third to 12th heats was 31 yuan / ton of steel. The corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 5.1 yuan / ton) + (1 heat * 63 yuan / ton * 120 tons / heater + 1 heat * 52 yuan / ton * 120 tons / heater + 10 heats * 31 yuan / ton * 120 tons / heater) = 7344 yuan + 51000 yuan = 58344 yuan.

[0164] Comparative Example 1: The tundish baking temperature is 1054℃, with 12 consecutive heats cast. The gas consumption cost is 3.8 yuan / ton of steel. The RH cost for heats 1-12 is 85 yuan / ton of steel. The corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 3.8 yuan / ton) + (12 heats * 85 yuan / ton * 120 tons / heater) = 5472 yuan + 122400 yuan = 127872 yuan.

[0165] Comparative Example 2: Tundish baking temperature 1170℃, 12 consecutive heats, gas consumption cost 4.3 yuan / ton of steel. RH cost for heats 1-12 is 85 yuan / ton of steel. The corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 4.3 yuan / ton) + (12 heats * 85 yuan / ton * 120 tons / heater) = 6192 yuan + 122400 yuan = 128592 yuan.

[0166] Comparative Example 3: The tundish baking temperature was 1289℃, with 12 consecutive heats cast. The gas consumption cost was 5.1 yuan / ton of steel. The RH cost for heats 1-12 was 85 yuan / ton of steel. The corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 5.1 yuan / ton) + (12 heats * 85 yuan / ton * 120 tons / heater) = 7344 yuan + 122400 yuan = 129744 yuan.

[0167] Comparative Example 4: Tundish baking temperature 1286℃, 12 consecutive heats, gas consumption cost 5.1 yuan / ton of steel. RH cost for heats 1-12 is 72 yuan / ton of steel. Corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 5.1 yuan / ton) + (12 heats * 72 yuan / ton * 120 tons / heater) = 7344 yuan + 103680 yuan = 111024 yuan.

[0168] Comparative Example 5: Tundish baking temperature 1053℃, 12 consecutive heats, gas consumption cost 3.8 yuan / ton of steel. The RH cost for heats 1-12 is 31 yuan / ton of steel. The corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heat * 3.8 yuan / ton) + (12 heats * 31 yuan / ton * 120 tons / heat) = 5472 yuan + 44640 yuan = 50112 yuan. (The tundish hydrogen content exceeds the 2.5ppm requirement, and the steel does not meet quality requirements).

[0169] Comparative Example 6: Tundish baking temperature 1052℃, 12 consecutive heats, gas consumption cost 3.8 yuan / ton of steel. RH cost of the first heat: 72 yuan / ton of steel; RH cost of the second heat: 63 yuan / ton of steel; RH cost of the third heat: 52 yuan / ton of steel; RH cost of the fourth to twelfth heats: 31 yuan / ton of steel. The corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 3.8 yuan / ton) + (1 heat * 72 yuan / ton * 120 tons / heater + 1 heat * 63 yuan / ton * 120 tons / heater + 1 heat * 52 yuan / ton * 120 tons / heater + 9 heats * 31 yuan / ton * 120 tons / heater) = 5472 yuan + 55920 yuan = 61392 yuan.

[0170] Comparative Example 7: Tundish baking temperature 1054℃, 12 consecutive heats, gas consumption cost 3.8 yuan / ton of steel. RH cost of the first heat: 63 yuan / ton of steel; RH cost of the second heat: 52 yuan / ton of steel; RH cost of the third to 12th heats: 31 yuan / ton of steel. Corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 3.8 yuan / ton) + (1 heat * 63 yuan / ton * 120 tons / heater + 1 heat * 52 yuan / ton * 120 tons / heater + 10 heats * 31 yuan / ton * 120 tons / heater) = 5472 yuan + 51000 yuan = 56472 yuan.

[0171] Comparative Example 8: Tundish baking temperature 1171℃, 12 consecutive heats, gas consumption cost 4.3 yuan / ton of steel. RH cost of the first heat: 85 yuan / ton of steel; RH cost of the second heat: 72 yuan / ton of steel; RH cost of the third heat: 63 yuan / ton of steel; RH cost of the fourth to sixth heats: 52 yuan / ton of steel; RH cost of the seventh to twelfth heats: 31 yuan / ton of steel. Correspondingly, the total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 4.3 yuan / ton) + (1 heat * 85 yuan / ton * 120 tons / heater + 1 heat * 72 yuan / ton * 120 tons / heater + 1 heat * 63 yuan / ton * 120 tons / heater + 3 heats * 52 yuan / ton * 120 tons / heater + 6 heats * 31 yuan / ton * 120 tons / heater) = 6192 yuan + 67440 yuan = 73632 yuan.

[0172] Comparative Example 9: Tundish baking temperature 1170℃, 12 consecutive heats, gas consumption cost 4.3 yuan / ton of steel. RH cost of the first heat: 63 yuan / ton of steel; RH cost of the second heat: 52 yuan / ton of steel; RH cost of the third to 12th heats: 31 yuan / ton of steel. Corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 4.3 yuan / ton) + (1 heat * 63 yuan / ton * 120 tons / heater + 1 heat * 52 yuan / ton * 120 tons / heater + 10 heats * 31 yuan / ton * 120 tons / heater) = 6192 yuan + 51000 yuan = 57192 yuan.

[0173] Comparative Example 10: Tundish baking temperature 1289℃, 12 consecutive heats, gas consumption cost 5.1 yuan / ton of steel. RH cost of the first heat: 85 yuan / ton of steel; the second heat: 72 yuan / ton of steel; the third heat: 63 yuan / ton of steel; the fourth to sixth heats: 52 yuan / ton of steel; the seventh to twelfth heats: 31 yuan / ton of steel. The corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 5.1 yuan / ton) + (1 heat * 85 yuan / ton * 120 tons / heater + 1 heat * 72 yuan / ton * 120 tons / heater + 1 heat * 63 yuan / ton * 120 tons / heater + 3 heats * 52 yuan / ton * 120 tons / heater + 6 heats * 31 yuan / ton * 120 tons / heater) = 7344 yuan + 67440 yuan = 74784 yuan.

[0174] Comparative Example 11: Tundish baking temperature 1286℃, 12 consecutive heats, gas consumption cost 5.1 yuan / ton of steel. RH cost of the first heat: 72 yuan / ton of steel; RH cost of the second heat: 63 yuan / ton of steel; RH cost of the third heat: 52 yuan / ton of steel; RH cost of the fourth to twelfth heats: 31 yuan / ton of steel. Corresponding total cost of gas plus RH = gas cost + RH cost = (12 heats * 120 tons / heater * 5.1 yuan / ton) + (1 heat * 72 yuan / ton * 120 tons / heater + 1 heat * 63 yuan / ton * 120 tons / heater + 1 heat * 52 yuan / ton * 120 tons / heater + 9 heats * 31 yuan / ton * 120 tons / heater) = 7344 yuan + 55920 yuan = 63264 yuan.

[0175] Detailed cost comparison, for example Figure 2 As shown.

[0176] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A low-cost RH treatment process, characterized in that, The number of continuous casting furnaces and the tundish baking temperature are divided into zones, and the RH treatment process is graded. Different graded RH processes are adopted according to the combination of different tundish baking temperatures and the number of continuous casting furnaces. The baking temperature zones for the continuous casting tundish are: T1: 1000℃~1100℃, T2: 1100℃~1200℃, T3: 1200℃~1300℃; The number of continuous casting furnaces is divided into the following zones: S1 is the first continuous casting furnace, S2 is the second continuous casting furnace, S3 is the third continuous casting furnace, S4 is the fourth to sixth continuous casting furnace, and S5 is the seventh or more continuous casting furnace. The RH process is classified as follows: RH-AAA, RH-AA, RH-A, RH-B, RH-C; The following graded RH processes are adopted according to the combination of different tundish baking temperatures and the number of continuous casting furnaces: T1+S1 is RH-AAA process, T1+S2 is RH-AA process, T1+S3 is RH-A process, T1+S4 is RH-B process; T2+S1 is RH-AA process, T2+S2 is RH-A process, T2+S3 is RH-B process; T3+S1 is RH-A process, T3+S2 is RH-B process; the rest are RH-C process; The RH-AAA process has a processing time of 15 minutes, a vacuum degree of 32 Pa, and a circulation flow rate of 130 Nm³. 3 / h; The RH-AA process has a processing time of 15 minutes, a vacuum level of 6000 Pa, and a circulation flow rate of 130 Nm³. 3 / h; The RH-A process has a processing time of 8 minutes, a vacuum level of 800 Pa, and a circulation flow rate of 130 Nm³. 3 / h; The RH-B process has a processing time of 8 minutes, a vacuum level of 6000 Pa, and a circulation flow rate of 75 Nm³. 3 / h; The RH-C process has a processing time of 5 minutes, a vacuum level of 6000 Pa, and a circulation flow rate of 75 Nm³. 3 / h.

2. The low-cost RH treatment process according to claim 1, characterized in that, The H content of the intermediate package was ≤2.5ppm.

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