Smelting method of cord steel 82B

Abstract

The present invention relates to the field of iron and steel metallurgy production, and discloses a smelting method of cord steel 82B. The method comprises sequentially subjecting the raw materials to converter smelting, LF refining, casting to obtain steel billets, and rolling the steel billets; wherein, converter smelting comprises: adding lime and low-grade fluorite to slag when the molten steel is tapped, adding silicon calcium barium powder for deoxidation, then adding aluminum blocks with the steel flow to deoxidize the molten steel, and then adding calcium carbide; after the steel is tapped, argon blowing treatment is performed, and calcium carbide is added in batches during the argon blowing treatment; LF refining comprises: after the molten steel from converter smelting enters the LF furnace, lime and low-grade fluorite are added to make refining slag; deoxidizers are added in batches to deoxidize the molten steel, and alloys are added to adjust the composition of the molten steel; and argon blowing treatment is performed. The method of the present invention can greatly save the cost of raw materials, shorten the LF refining time, and improve the production efficiency of cord steel.

Description

Technical Field

[0001] The invention relates to the field of iron and steel metallurgical production, and in particular to a smelting method of cord steel 82B. Background Art

[0002] Cord steel is a representative product of ultra-clean steel. It has excellent mechanical properties such as good elasticity, high strength, impact resistance and long service life. The annual demand for cord steel in the consumer market is about 3 million tons. Cord steel is the base material for manufacturing steel cord and is known as the "crown jewel of wire products."

[0003] At present, the common process flow for producing cord steel in China is converter smelting - ladle furnace refining (LF refining) - RH (VD) - billet continuous casting. For example, patent application CN101831521A discloses a method for producing cord steel, which includes smelting, refining, continuous casting and rolling. The specific process of refining and making refined slag includes the following steps: after 120t LF furnace molten steel enters the station, lime and high-grade fluorite are added to make slag, followed by deoxidation and desulfurization treatment, and then special refining slag for cord steel is added after completion. After melting, the composition of the refined slag meets the smelting process requirements. In the prior art, the raw material high-grade fluorite used in the refining process is composed of SiO 2 (12-20%), CaF 2 (75-85%), the cord steel refined slag composition is CaO (40-45%), SiO2 (50-55%), MgO (0.5-2%) and Al 2 O 3 (0.5-1%), and the content of silicon dioxide in the refining slag of cord steel 82B is required to be 20-30% during the refining process. Fluorite ore for smelting generally requires that the mass fraction of calcium fluoride is greater than 70%. Its product quality is implemented in accordance with the national standard of the People's Republic of China GB8216-87 "Fluorite Lump Ore", which has certain requirements for the main impurity silicon dioxide. Therefore, the silicon dioxide content in fluorite for smelting is very low. However, the silicon dioxide content in the slag of cord steel is relatively high. Therefore, during the smelting process, it is necessary to add cord steel special refined slag with high silicon dioxide content into the molten steel to increase the silicon dioxide content of the final slag.

[0004] Therefore, for the current process of smelting cord steel, on the one hand, high-priced high-grade fluorite with low silica content is used in the smelting process, and on the other hand, special refined slag for cord steel with high silica content is added again to increase the silica content of the final slag. There is a lot of cost and time waste in the process materials.

[0005] Fluorite often coexists with minerals such as quartz, barite, and quartz. Different coexisting minerals have different mineralization effects. The quartz in fluorite exists as free silicon dioxide. Since the coexistence itself will consume some fluoride ions, the higher the silicon dioxide content in fluorite, the lower the grade of fluorite, and it cannot be used in many fields. Therefore, low-grade fluorite with coexisting quartz and other minerals is abundant and cheap. Low-grade fluorite usually cannot be directly used in steelmaking, but low-grade fluorite is cheap, and the SiO 2 The content of fluorite is relatively high, and it is of great practical significance to research and develop a method for smelting cord steel using low-grade fluorite. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a smelting method of cord steel 82B, which can significantly reduce the production cost of cord steel, save production time and improve production efficiency.

[0007] In order to achieve the above-mentioned object, the present invention provides a method for preparing cord steel 82B, which comprises sequentially subjecting the raw materials to converter smelting, LF refining, casting to obtain a steel billet, and rolling the steel billet;

[0008] Among them, converter smelting includes: adding lime and low-grade fluorite to make slag when molten steel is tapped, adding silicon calcium barium powder for deoxidation, then adding aluminum blocks with the steel flow to deoxidize the molten steel, and then adding calcium carbide; after the steel is tapped, argon blowing is carried out, and calcium carbide is added in batches during the argon blowing process;

[0009] LF refining includes: after the molten steel from converter smelting enters the LF furnace, lime and low-grade fluorite are added to make refining slag; deoxidizer is added in batches to deoxidize the molten steel, and alloy is added to adjust the composition of the molten steel; argon blowing treatment is performed;

[0010] Among them, the addition amount of low-grade fluorite in converter smelting is 0.78-0.82 kg / ton 钢水 ;

[0011] The amount of low-grade fluorite added in LF refining is 2.3-3.3 kg / ton 钢水 ;

[0012] The total weight of low-grade fluorite is 100 wt%, of which SiO 2 The content is 40-50% by weight, CaF 2 The content is 50-60% by weight.

[0013] Preferably, in LF refining, the amount of lime added is 2.3-4.1 kg / ton 钢水 .

[0014] Preferably, in the steel-making process of converter smelting, the specific step of adjusting the amount of calcium carbide added according to the mass percentage of C in the molten steel includes: when the mass percentage of C in the molten steel is less than 0.08%, the amount of calcium carbide added is 1-1.2 kg / ton 钢水 When the mass percentage of C in molten steel is 0.08%-0.15%, the amount of calcium carbide added is 0.8-1 kg / ton 钢水 When the mass percentage of C in molten steel is ≥0.15%, the amount of calcium carbide added is 0.6-0.8 kg / ton 钢水 .

[0015] Preferably, in converter smelting, the amount of aluminum blocks added is 0.31-0.33 kg / ton 钢水 .

[0016] Preferably, in converter smelting, the flow rate of argon during argon blowing treatment is 600-1000 L / min, and the time of argon blowing treatment is 5-10 min.

[0017] Preferably, in LF refining, the refining slag contains 20-30 wt% SiO 2 , 3-10 wt% Al 2 O 3 , 45-55 wt. % CaO and 2-5 wt. % MgO.

[0018] Preferably, the raw materials include molten iron and scrap steel, and the weight ratio of the molten iron to the scrap steel is 1:0.083-0.125.

[0019] Preferably, the content of Si element in the molten iron is 0.3-0.5 weight %, the content of S element is ≤0.05 weight %, the content of P element is ≤0.1 weight %, and the content of Ti element is ≤0.05 weight %.

[0020] Preferably, the temperature of the molten iron is T≥1250°C.

[0021] Preferably, the amount of slag in the molten iron should not exceed 0.5% by weight.

[0022] Preferably, the burn-through rate of the lime is >92%.

[0023] Preferably, the activity of lime is ≥280 and the overburning rate is ≤3%.

[0024] Preferably, the content of CaO in lime is ≥85% by weight, and the content of SiO 2 The content of is ≤2.5% by weight, the sum of the content of P and S elements is ≤0.05% by weight, and the moisture content is ≤0.5% by weight.

[0025] Preferably, the length, width and height of the lime are 5-40 mm.

[0026] Preferably, in converter smelting, calcium carbide is added 2-5 times during argon blowing treatment.

[0027] Preferably, the amount of calcium carbide added each time is 0.15-0.17 kg / ton 钢水 .

[0028] Preferably, in converter smelting, the amount of lime added is 3.1-3.3 kg / ton 钢水 .

[0029] Preferably, in converter smelting, the amount of silicon-calcium-barium alloy added is 0.9-1 kg / ton 钢水 .

[0030] The method of the present invention can be used to prepare cord steel 82B that meets national requirements, and the method of the present invention can reduce the steps of the refining process. After adding low-grade fluorite and lime to make refining slag, the obtained refined slag can meet the smelting requirements of cord steel 82B, and there is no need to add cord steel special refining slag again to increase the SiO2 content of the refining slag. 2 content, reducing the basicity of the refining slag, simplifying the LF refining process, saving the preparation cost, and the cost of the low-grade fluorite used in the present invention is also much lower than the high-grade fluorite commonly used in the prior art. Therefore, the method described in the present invention can greatly save the preparation cost by smelting cord steel 82B, and can also shorten the time of the original refining process, improve the overall production effect of cord steel 82B, and have great industrial application prospects. At the same time, the present invention further controls the steel tapping in the converter smelting, thereby further improving the quality of cord steel 82B. At the same time, it is very important that the product composition, inclusion content and troostite content of cord steel 82B prepared by the method described in the present invention can meet the national requirements and standards, indicating that the method described in the present invention can also obtain a cord steel 82B product that meets the requirements. The method described in the present invention not only saves the production cost of cord steel 82B, but also improves the production efficiency of cord steel 82B, and also provides a new idea for the utilization of low-grade fluorite, and its industrial application prospects are broad. DETAILED DESCRIPTION

[0031] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0032] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0033] In this article, the low-grade fluorite refers to the total weight of the low-grade fluorite as 100% by weight, and the CaF 2 The content is less than 60% by weight, SiO 2 The content of CaF in fluorite is higher than 40% by weight; the high-grade fluorite refers to the CaF 2 Content ≥ 85% by weight, SiO 2 The content is 12-15% by weight.

[0034] In this article, the burn-through rate of lime refers to the weight percentage of remaining limestone after removing the incompletely decomposed and over-calcined limestone after calcination; activity refers to the ability of lime to react with other substances in the slag; overburn rate refers to the weight percentage of over-calcined limestone during the limestone calcination process.

[0035] Herein, the refining slag refers to the slag obtained by adding specific slag-forming materials during the refining process.

[0036] In this article, the basicity of the refining slag refers to the weight concentration of the basic CaO and the acidic oxide SiO in the refining slag. 2 The weight concentration ratio.

[0037] In this article, the "five harmful elements" refer to As, Sn, Pb, Sb and Bi.

[0038] On one hand, the present invention provides a smelting method of cord steel 82B, which comprises sequentially subjecting raw materials to converter smelting, LF refining, casting to obtain steel billets, and rolling the steel billets.

[0039] In the method described in the present invention, converter smelting includes blowing the raw materials and tapping the steel, wherein the blowing of the raw materials is carried out according to common means in the art, which will not be described in detail here.

[0040] In the method described in the present invention, converter smelting includes: adding lime and low-grade fluorite to make slag when molten steel is tapped, adding silicon calcium barium powder for deoxidation, then adding aluminum blocks with the steel flow to deoxidize the molten steel, and then adding calcium carbide; after the steel is tapped, argon blowing treatment is performed, and calcium carbide is added in batches during the argon blowing treatment;

[0041] LF refining includes: after the molten steel from converter smelting enters the LF furnace, lime and low-grade fluorite are added to make refining slag; deoxidizers are added in batches to deoxidize the molten steel, and alloys are added to adjust the composition of the molten steel; and argon blowing treatment is performed.

[0042] In a specific embodiment, the amount of low-grade fluorite added in converter smelting is 0.78-0.82 kg / ton 钢水 Specifically, the amount of low-grade fluorite added can be 0.78 kg / ton 钢水 , 0.789, kg / ton 钢水 , 0.79 kg / ton 钢水 , 0.795 kg / ton 钢水 , 0.8 kg / ton 钢水 , 0.805 kg / ton 钢水 , 0.81 kg / ton 钢水 , 0.816 kg / ton 钢水 or 0.82 kg / ton 钢水 .

[0043] In a specific embodiment, in converter smelting, the amount of lime added is 3.1-3.3 kg / ton 钢水 Specifically, the amount of lime added can be 3.1 kg / ton 钢水 , 3.11 kg / ton 钢水 , 3.155 kg / ton 钢水 , 3.12 kg / ton 钢水 , 3.13 kg / ton 钢水 , 3.14 kg / ton 钢水 , 3.15 kg / ton 钢水 , 3.16 kg / ton 钢水 , 3.17 kg / ton 钢水 , 3.18 kg / ton 钢水 , 3.19 kg / ton 钢水 , 3.2 kg / ton 钢水 , 3.25 kg / ton 钢水 , 3.26 kg / ton 钢水 or 3.3 kg / ton 钢水 .

[0044] In a specific embodiment, in converter smelting, the amount of silicon calcium barium powder added is 0.9-1 kg / ton 钢水 Specifically, the amount of silicon calcium barium powder added can be 0.9 kg / ton 钢水 , 0.91 kg / ton 钢水 , 0.92 kg / ton 钢水 , 0.93 kg / ton 钢水 , 0.94 kg / ton 钢水 , 0.946 kg / ton钢水 , 0.95 kg / ton 钢水 , 0.96 kg / ton 钢水 , 0.97 kg / ton 钢水 , 0.98 kg / ton 钢水 , 0.99 kg / ton 钢水 or 1 kg / ton 钢水 .

[0045] In the method of the present invention, the total weight of the low-grade fluorite is 100 weight percent, and the low-grade fluorite contains 40-50 weight percent of SiO 2 and 50-60 wt% CaF 2 Specifically, the SiO in the low-grade fluorite 2 The content of CaF may be 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt% or 50 wt%; 2 The content of may be 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt% or 60 wt%.

[0046] In the method described in the present invention, the raw materials include molten iron and scrap steel, and the weight ratio of the molten iron to the scrap steel is 1:0.083-0.125.

[0047] In a specific embodiment, the molten iron can also be used as a steel raw material for steelmaking. The content of Si element in the molten iron is 0.3-0.5 weight%, the content of S element is ≤0.05 weight%, the content of P element is ≤0.1 weight%, the content of Ti element is ≤0.05 weight%, the temperature of the molten iron T is ≥1250°C, and the amount of slag in the molten iron shall not exceed 0.5 weight%.

[0048] In a specific embodiment, the burn-through rate of lime is greater than 92%. The activity of lime is greater than or equal to 280, the overburning is less than or equal to 3%, the CaO content in lime is greater than or equal to 85% by weight, and the SiO 2 The content of is ≤2.5% by weight, the sum of the P and S element contents is ≤0.05% by weight, the moisture content is ≤0.5% by weight, and the length, width and height of the lime are 5-40mm.

[0049] In the method of the present invention, during the steel tapping process of converter smelting, aluminum blocks need to be added to cooperate with the deoxidation of molten steel. The aluminum blocks can provide precipitation deoxidation function. Based on the weight of the molten steel obtained by blowing in the converter smelting, the amount of aluminum blocks added is 0.31-0.33 kg / ton. 钢水 Specifically, the amount of aluminum block added can be 0.31 kg / ton 钢水 , 0.315 kg / ton钢水 , 0.32 kg / ton 钢水 , 0.326 kg / ton molten steel or 0.33 kg / ton 钢水 .

[0050] In the method described in the present invention, during converter smelting, after adding aluminum blocks for deoxidation, calcium carbide needs to be added to further strengthen the slag surface for diffusion deoxidation. The amount of calcium carbide added needs to be adjusted according to the mass percentage of C in the molten steel. Calcium carbide is added as a deoxidizer to strengthen diffusion deoxidation and prevent oxidation of the molten steel surface.

[0051] In a specific implementation, in the converter smelting, in order to make the quality of cord steel 82B meet the standard requirements of GB / T 24238-2017, the amount of calcium carbide added is adjusted according to the mass percentage of C in the molten steel. The specific steps include: when the mass percentage of C in the molten steel is less than 0.08%, the amount of calcium carbide added is 1-1.2 kg / ton 钢水 When the mass percentage of C in molten steel is 0.08%-0.15%, the amount of calcium carbide added is 0.8-1 kg / ton 钢水 When the mass percentage of C in molten steel is ≥0.15%, the amount of calcium carbide added is 0.6-0.8 kg / ton 钢水 .

[0052] In the method described in the present invention, in the converter smelting, after the steel is tapped, the obtained molten steel needs to be subjected to argon blowing treatment to desulfurize the molten steel. During the desulfurization, it is also necessary to add a deoxidizer, calcium carbide, for deoxidation, so that the contents of oxygen and sulfur elements in the molten steel entering the LF refining process meet the composition requirements for cord steel 82B in the national standard GB / T 24238-2017 "Hot-rolled wire rod for prestressed steel wire and steel strand".

[0053] In a specific embodiment, in converter smelting, the flow rate of argon gas during argon blowing treatment is 600-1000 L / min, and the time of argon blowing treatment is 5-10 min. Specifically, the flow rate of argon gas during argon blowing treatment can be 600 L / min, 700 L / min, 800 L / min, 900 L / min or 1000 L / min; the time of argon blowing treatment can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0054] In a preferred embodiment, during the converter smelting, the number of times calcium carbide is added during the argon blowing treatment is 2-5 times, more preferably 3 times, and the amount of calcium carbide added each time is 0.15-0.17 kg / ton based on the weight of the molten steel obtained by blowing in the converter smelting. 钢水 Specifically, the amount of calcium carbide added each time can be 0.15 kg / ton 钢水 , 0.155 kg / ton钢水 , 0.157 kg / ton 钢水 , 0.16 kg / ton 钢水 , 0.163 kg / ton 钢水 , 0.165 kg / ton 钢水 or 0.175 kg / ton 钢水 .

[0055] In the method of the present invention, at the end of converter smelting, the temperature of the molten steel entering the LF head furnace is >1530°C.

[0056] In a specific embodiment, the LF refining process includes: after the molten steel from the converter smelting is completed, lime and low-grade fluorite are added to make refining slag, and during the power transmission process, the first batch of deoxidizers are added, and the amount of calcium carbide added in the first batch of deoxidizers is 0.31-0.49 kg / ton. 钢水 Then take the refined slag sample every 5-8 minutes to observe the color. If the color cannot remain white, continue to add the second batch of deoxidizer to strengthen the diffusion deoxidation of the refined slag surface until white slag is produced. The amount of the second batch of deoxidizer added is 0.15-0.32 kg / ton 钢水 , so that the refined slag maintains good fluidity and reducibility, and allows the refined slag to directly meet the final smelting process requirements. During the LF refining process, the refined slag is dipped every 5-8 minutes to observe the color, and the third batch of deoxidizer is added to keep the refined slag white. The amount of the third batch of deoxidizer added is 0.035-0.081 kg / ton 钢水 , the time for the refined slag to remain white needs to be greater than 20 minutes. Then test the composition of the molten steel, add alloys according to the test data to adjust the composition of the molten steel, so that the composition of the molten steel reaches the range required by the national standard GB / T24238-2017. When the molten steel temperature reaches (1494℃+casting temperature drop+soft blowing temperature drop+calcium treatment temperature drop)±5℃, argon blowing treatment is carried out, and the argon flow rate is adjusted to 100-200L / min. After argon blowing treatment for 20-30 minutes, the molten steel can be discharged and transferred to the casting process.

[0057] In a specific embodiment, in LF refining, the addition amount of low-grade fluorite is 2.3-3.3 kg / ton 钢水 Specifically, the amount of low-grade fluorite added can be 2.2 kg / ton of molten steel, 2.5 kg / ton 钢水 , 2.6 kg / ton 钢水 , 2.8 kg / ton 钢水 , 2.857 kg / ton 钢水 , 3 kg / ton 钢水 , 3.1 kg / ton 钢水 , 3.2 kg / ton 钢水 , 3.26 kg / ton 钢水or 3.3 kg / ton 钢水 .

[0058] In a specific embodiment, in LF refining, the amount of lime added is 2.3-4.1 kg / ton 钢水 Specifically, the amount of lime added can be 2.3 kg / ton 钢水 , 2.5 kg / ton 钢水 , 2.8 kg / ton 钢水 , 3.0 kg / ton 钢水 , 3.2 kg / ton 钢水 , 3.26 kg / ton 钢水 , 3.5 kg / ton 钢水 , 3.55 kg / ton 钢水 , 3.8 kg / ton 钢水 , 4 kg / ton 钢水 , 4.08 kg / ton 钢水 or 4.1 kg / ton 钢水 .

[0059] In a specific embodiment, in LF refining, the first batch of deoxidizers, the second batch of deoxidizers and the third batch of deoxidizers are each independently selected from calcium carbide or silicon carbide.

[0060] In the method described in the present invention, in LF refining, lime and high-grade fluorite are used to make refining slag in the prior art. During the power supply process of the electric furnace, calcium carbide and silicon carbon powder need to be added for diffusion deoxidation. After the auxiliary materials are melted, the composition of the slag is as follows: SiO 2 The content is 10-16% by weight, Al 2 O 3 The content of SiO is 10-18 wt%, the content of CaO is 50-58 wt%, the content of MgO is 4-6 wt%, and the basicity of the refined slag is 3.2-3.8. 2 The content of SiO2 in the refined slag does not meet the requirements for smelting cord steel 82B, so it is necessary to add cord steel special refined slag again to reduce the SiO2 in the refined slag. 2 However, the method of the present invention uses low-grade fluorite and lime to make refining slag in LF refining, and SiO can be directly obtained. 2 The content and basicity of the refined slag meet the national requirements. There is no need to add special refined slag for cord steel to adjust the composition and basicity of the refined slag. The subsequent smelting process can be carried out directly, which greatly saves the cost of raw materials and shortens the LF refining time. The production rate of cord steel is further improved and new uses for low-grade fluorite are opened up.

[0061] In a specific embodiment, the composition of the refined slag includes 20-30 wt% SiO 2 , 3-10 wt% Al 2 O 3 , 45-55 wt.% CaO and 2-5 wt.% MgO, and the basicity is 1.8-2.5.

[0062] In the method of the present invention, in LF refining, the alloy is selected from one of ferrosilicon (FeSi72), silicomanganese (FeMn68Si18) and high carbon ferrochrome (FeCr55C10.0), and the amount of the alloy added is calculated according to the target value of the element specified in the standard GB / T24238-2017. The specific calculation formula is as follows:

[0063] (Target value of the element in GB / T24238-2017 national standard - content of the element entering the station) × amount of molten steel / grade of the alloy element / yield of the element.

[0064] In the present invention, the casting to obtain the steel billet and the rolling of the steel billet can be carried out according to conventional techniques in the art, which will not be described in detail herein.

[0065] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

[0066] The preparation method of the cord steel 82B comprises the following steps: sequentially subjecting the raw materials to converter smelting, LF refining, casting to obtain a steel billet, and rolling the steel billet;

[0067] The detailed operation steps of converter smelting and LF refining used in Examples 1-3 are as follows.

[0068] Example 1

[0069] Converter smelting: 120 tons of molten iron and 10 tons of scrap steel are blown in the converter to obtain primary molten steel; 3.26kg / t is added when the molten steel is tapped 钢水 Lime, 0.816kg / t 钢水 Low-grade fluorite (SiO 2 The content of CaF is 45% by weight 2 The content is 50% by weight) slag, followed by adding 0.98kg / t 钢水 The molten steel is deoxidized by silicon-calcium-barium alloy, and then 0.326kg / t is added along with the steel flow. 钢水 The aluminum block was used to deoxidize the molten steel; the mass percentage of C in the molten steel before tapping was 0.12%, and 0.98 kg / t 钢水After the steel is tapped, argon blowing is performed for desulfurization. The flow rate of argon is 1000L / min, and the time of argon blowing is 5min. Calcium carbide is added three times during the argon blowing treatment, and 0.163kg / t is added each time. 钢水 After the argon blowing treatment, the molten steel is stirred for 5 minutes and then sampled to confirm that the sulfur content of the molten steel meets the national standard requirements. The molten steel is then transported to the LF furnace. The temperature of the molten steel at the head of the LF furnace is 1531℃.

[0070] LF refining: After the molten steel from the converter enters the LF furnace, 3.26kg / t 钢水 of lime and 2.857kg / t 钢水 Low-grade fluorite is used to make refining slag; during the power transmission process, 0.408kg / t 钢水 The first batch of deoxidizer silicon carbide was used to deoxidize the molten steel. The refined slag samples were taken every 5 minutes to observe the color until white refined slag was produced. Then 0.244 kg / t was added again. 钢水 The second batch of deoxidizer silicon carbide was used to keep the refining slag white; during the LF refining process, the refining slag was dipped every 5 minutes to observe the color and 0.0408 kg / t 钢水 The third batch of deoxidizer silicon carbide keeps the refining slag white. After the refining slag keeps white for more than 20 minutes, the composition of the molten steel is tested, and ferrosilicon (FeSi72), silicon manganese (FeMn68Si18) and high carbon ferrochrome alloy (FeCr55C10.0) are added to adjust the composition of the molten steel so that the composition of the molten steel meets the requirements of cord steel 82B. Then, argon blowing treatment is carried out, and the argon flow rate is adjusted to 100L / min. After argon blowing treatment for 20 minutes, the molten steel can be discharged from the station and transferred to the casting process;

[0071] The burn-through rate of lime is greater than 92%, the activity of lime is greater than or equal to 280, the overburning rate is less than or equal to 3%, the CaO content in lime is 85% by weight, and the SiO 2 The content of is 2.5 weight %, the sum of P and S elements is 0.05 weight %, the water content is 0.5 weight %, and the length, width and height of the lime are 5 mm;

[0072] The content of Si element in the molten iron is 0.3 wt%, the content of S element is 0.05 wt%, the content of P element is 0.1 wt%, the content of Ti element is 0.05 wt%, the temperature T of the molten iron is 1250° C., and the amount of slag in the molten iron is 0.5 wt%;

[0073] The refined slag contains 25.3 wt% SiO 2 , 7.2 wt% Al 2 O 3 , 52.8 wt% CaO and 4.5 wt% MgO, with a basicity of 2.09.

[0074] Example 2

[0075] Converter smelting: 120 tons of molten iron and 15 tons of scrap steel are blown in the converter, and 3.155 kg / t is added when tapping. 钢水 Lime, 0.789kg / t 钢水 Low-grade fluorite (SiO 2 The content of CaF is 45% by weight 2 The content is 50% by weight) slag, followed by adding 0.946kg / t 钢水 The molten steel is deoxidized by silicon-calcium-barium alloy, and then 0.315kg / t is added along with the steel flow. 钢水 The aluminum block was used to deoxidize the molten steel; the mass percentage of C in the molten steel before tapping was 0.07%, and 1.104 kg / t was added 钢水 After the steel is tapped, argon blowing is performed for desulfurization. The flow rate of argon is 1000L / min, and the time of argon blowing is 5min. Calcium carbide is added three times during the argon blowing treatment, and 0.157kg / t is added each time. 钢水 After stirring for 5 minutes, take a sample to confirm that the sulfur content of the molten steel meets the national standard, and then transport the molten steel to the LF furnace. The temperature of the molten steel in the LF furnace is 1532℃;

[0076] LF refining: After the molten steel from converter smelting enters the LF furnace, 3.55kg / t 钢水 of lime and 3kg / t 钢水 Low-grade fluorite is used to make refining slag; during the power transmission process, 0.473kg / t 钢水 The first batch of deoxidizer silicon carbide was used to deoxidize the molten steel. The refined slag samples were taken every 5 minutes to observe the color until white refined slag was produced. Then 0.236 kg / t was added again. 钢水 The second batch of deoxidizer silicon carbide was used to keep the refining slag white; during the LF refining process, the refining slag was dipped every 5 minutes to observe the color and 0.04kg / t 钢水 The third batch of deoxidizer silicon carbide keeps the refining slag white. After the white refining slag is kept for more than 20 minutes, the composition of the molten steel is tested, and ferrosilicon (FeSi72), silicon manganese (FeMn68Si18) and high carbon ferrochrome alloy (FeCr55C10.0) are added to adjust the composition of the molten steel so that the composition of the molten steel meets the requirements of cord steel 82B. Then, argon blowing treatment is carried out, and the argon flow rate is adjusted to 120L / min. After argon blowing treatment for 20 minutes, the molten steel can be discharged from the station and transferred to the casting process;

[0077] The content of Si element in the molten iron is 0.3 wt%, the content of S element is 0.05 wt%, the content of P element is 0.1 wt%, the content of Ti element is 0.05 wt%, the temperature T of the molten iron is 1250° C., and the amount of slag in the molten iron is 0.5 wt%;

[0078] The refined slag contains 26.2 wt% SiO 2 , 5.5 wt% Al 2 O 3 , 53.3 wt.% CaO and 4.1 wt.% MgO, with a basicity of 2.03.

[0079] Example 3

[0080] Converter smelting: 120 tons of molten iron and 10 tons of scrap steel are blown in the converter, and 3.26 kg / t is added when tapping. 钢水 Lime, 0.816kg / t 钢水 Low-grade fluorite (SiO 2 The content of CaF is 40% by weight 2 The content is 55% by weight) slag, followed by adding 0.98kg / t 钢水 of barium silicate, and then add 0.326kg / t with the steel flow 钢水 The aluminum block was used to deoxidize the molten steel; the mass percentage of C in the molten steel before tapping was 0.15%, and 0.775kg / t 钢水 After the steel is tapped, argon blowing is performed for desulfurization. The flow rate of argon is 1000L / min, and the time of argon blowing is 5min. Calcium carbide is added three times during the argon blowing treatment, and 0.163kg / t is added each time. 钢水 After stirring for 5 minutes, take a sample to confirm that the sulfur content of the molten steel meets the national standard, and then transport the molten steel to the LF furnace. The temperature of the molten steel in the LF furnace is 1535℃;

[0081] LF refining: After the molten steel from converter smelting enters the LF furnace, 4.08kg / t 钢水 of lime and 3.26kg / t 钢水 Low-grade fluorite is used to make refining slag; during the power transmission process, 0.408kg / t 钢水 The first batch of deoxidizer silicon carbide was used to deoxidize the molten steel. The refined slag samples were taken every 5 minutes to observe the color until white refined slag was produced. Then 0.244 kg / t was added again. 钢水 The second batch of deoxidizer silicon carbide was used to keep the refining slag white; during the LF refining process, the refining slag was dipped every 5 minutes to observe the color and 0.04kg / t 钢水The third batch of deoxidizer silicon carbide keeps the refining slag white. After the white refining slag is kept for more than 20 minutes, the composition of the molten steel is tested, and ferrosilicon (72FeSi), silicon manganese (Si18Mn65) and high carbon ferrochrome alloy (FeCr55) are added to adjust the composition of the molten steel so that the composition of the molten steel meets the requirements of cord steel 82B. Then, argon blowing treatment is carried out, and the argon flow rate is adjusted to 150L / min. After argon blowing treatment for 20 minutes, the molten steel can be discharged from the station and transferred to the casting process;

[0082] The content of Si element in the molten iron is 0.3 wt%, the content of S element is 0.05 wt%, the content of P element is 0.1 wt%, the content of Ti element is 0.05 wt%, the temperature T of the molten iron is 1250° C., and the amount of slag in the molten iron is 0.5 wt%;

[0083] The refined slag contains 24.1 wt% SiO 2 , 6.2 wt% Al 2 O 3 , 48.6 wt% CaO and 4.8 wt% MgO, and the basicity is 2.02.

[0084] Comparative Example 1

[0085] The method described in Example 1 was followed, except that 4.24 kg / t 钢水 Lime and 1.63kg / t 钢水 Low-grade fluorite is used for smelting;

[0086] The refined slag contains 17.5 wt% SiO 2 , 6.6 wt% Al 2 O 3 , 55.3 wt% CaO and 5.6 wt% MgO, and the basicity is 3.16.

[0087] Comparative Example 1: SiO 2 The content and basicity (alkalinity needs to be in the range of 1.8-2.5) no longer meet the production process requirements of cord steel 82B.

[0088] Test Case

[0089] Test Example 1

[0090] Composition detection of cord steel 82B: The composition of the cord steel 82B obtained in Examples 1-3 and the product obtained in Comparative Example 1 was detected. The test results are shown in Table 1.

[0091] Table 1

[0092]

[0093] It can be seen from Table 1 that the chemical composition of the cord steel 82B prepared by the preparation method of the present invention meets the requirements of standard GB / T24238-2017, indicating that the method described in the present invention can successfully prepare products that meet the requirements without adversely affecting the product composition of the cord steel 82B.

[0094] Test Example 2

[0095] Inclusion detection in cord steel 82B: According to the provisions of GB / T 10561-2005 on microscopic evaluation of non-metallic inclusions in steel, inclusions are divided into four categories: A, B, C, and D according to their morphology and distribution. Each type of inclusion is divided into coarse and fine series according to thickness or diameter, and is divided into 1 to 5 levels according to quantity. The higher the level, the more inclusions. Among them, category A is sulfide long strip inclusions, category B is alumina fragment string inclusions, category C is silicate inclusions, category D is spherical dispersed oxide inclusions, and category Ds is large particle inclusions. The numbers 0.5, 1.0 and 1.5 are the ratings of various types of inclusions. The test results are shown in Table 2.

[0096] Table 2

[0097]

[0098] It can be seen from Table 2 that the cord steel 82B prepared by the method of the present invention has very low inclusions, which meets the requirements of the cord steel 82B for the inclusion content. It can also be shown that the method of the present invention can prepare the cord steel 82B that meets the product property requirements.

[0099] Test Example 3

[0100] Detection of the content of troostite in cord steel 82B: The content of troostite in the cord steel 82B obtained in Examples 1-3 and the product obtained in Comparative Example 1 was detected according to the method of YB / T 169-2017. The test results are shown in Table 3.

[0101] Table 3

[0102] Example No. Specification The content of troostite in three microscopic fields Example 1 Φ13 85％、85％、90％ Example 2 Φ13 85％、85％、85％ Example 3 Φ13 85％、90％、85％ Comparative Example 1 Φ13 85％、80％、85％

[0103] It can be seen from Table 3 that the content of troostite in the cord steel 82B prepared by the method described in the present invention is all greater than 85%, which meets the requirements of the standard GB / T24238-2017 for the content of troostite in the cord steel 82B. Therefore, the method described in the present invention can be successfully used to prepare a cord steel 82B product that meets the standard. It can be seen from the data of Comparative Example 1 that the product obtained at this time no longer meets the national standard requirements.

[0104] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A smelting method for cord steel 82B, characterized in that: The method comprises sequentially performing converter smelting, LF refining, casting to obtain steel billets, and rolling the steel billets; Among them, converter smelting includes: adding lime and low-grade fluorite to make slag when molten steel is tapped, adding silicon calcium barium powder for deoxidation, then adding aluminum blocks with the steel flow to deoxidize the molten steel, and then adding calcium carbide; after the steel is tapped, argon blowing is carried out, and calcium carbide is added in batches during the argon blowing process; LF refining includes: after the molten steel from converter smelting enters the LF furnace, lime and low-grade fluorite are added to make refining slag; deoxidizer is added in batches to deoxidize the molten steel, and alloy is added to adjust the composition of the molten steel; argon blowing treatment is performed; Among them, the addition amount of low-grade fluorite in converter smelting is 0.78-0.82 kg / ton 钢水 ; The amount of low-grade fluorite added in LF refining is 2.3-3.3 kg / ton 钢水 ; The total weight of the low-grade fluorite is 100 weight %, wherein the content of SiO2 is 40-50 weight %, and the content of CaF2 is 50-60 weight %; In LF refining, the amount of lime added is 2.3-4.1 kg / ton 钢水 ; In the process of tapping steel in converter smelting, when the mass percentage of C in molten steel is less than 0.08%, the amount of calcium carbide added is 1-1.2 kg / ton 钢水 When the mass percentage of C in molten steel is 0.08%-0.15%, the amount of calcium carbide added is 0.8-1 kg / ton 钢水 When the mass percentage of C in molten steel is ≥0.15%, the amount of calcium carbide added is 0.6-0.8 kg / ton 钢水 ; In converter smelting, the amount of lime added is 3.1-3.3 kg / ton 钢水 .

2. The smelting method of the cord steel 82B according to claim 1, characterized in that: In converter smelting, the amount of aluminum blocks added is 0.31-0.33 kg / ton 钢水 .

3. The smelting method of the cord steel 82B according to claim 1, characterized in that: In converter smelting, the flow rate of argon during argon blowing treatment is 600-1000L / min, and the time of argon blowing treatment is 5-10min.

4. The smelting method of the cord steel 82B according to claim 1, characterized in that: The raw materials include molten iron and scrap steel, and the weight ratio of the molten iron to the scrap steel is 1:0.083-0.

125.

5. The smelting method of the cord steel 82B according to claim 1, characterized in that: In converter smelting, calcium carbide is added 2-5 times during argon blowing treatment.

6. The smelting method of the cord steel 82B according to claim 5, characterized in that: The amount of calcium carbide added each time is 0.15-0.17 kg / ton 钢水 .

7. The smelting method of the cord steel 82B according to claim 1, characterized in that: In converter smelting, the addition amount of silicon calcium barium powder is 0.9-1 kg / ton 钢水 .

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