Method for directly opening head furnace for smelting cold heading steel by using silicon molten iron

Abstract

The invention relates to the field of steelmaking, and discloses a method for directly opening a silicon high molten iron smelting cold heading steel head furnace, which comprises the following steps of: starting power transmission when molten steel reaches an LF furnace, and adding slag charge into the molten steel after the power transmission is started; the method comprises the following steps of: when power is supplied until the temperature of the molten steel reaches 1590-1610 DEG C, sampling I, preparing acid-soluble aluminum to 0.054-0.056% and silicon to 0.038-0.042% according to a detection result of the sample I, uniformly stirring argon, sampling II, preparing acid-soluble aluminum to 0.031-0.033%, silicon to 0.065-0.075% and manganese to 0.015-0.019% according to a result of the sample II, then feeding a calcium wire until the calcium content in the molten steel is 30ppm-55ppm, and finally softly blowing for 12-15min and discharging. The method can realize the direct opening of the cold forging steel head furnace.

Description

Technical Field

[0001] The invention relates to the technical field of steelmaking, in particular to a method for directly opening a furnace for smelting cold heading steel with silicon high iron water. Background Art

[0002] Usually, when smelting cold heading steel in the first process of steelmaking, aluminum-free steel is needed for the first furnace to make transition. For example, Q195LB is needed for the first furnace of SWRCH6A, and SWRCH6A is used from the second furnace. The same is true for other types of cold heading steel. At present, attempts have been made to open the cold heading steel head furnace directly, but all have failed. The main reason is that when the large ladle of molten steel is put into the middle ladle, the molten steel cannot be pulled out as soon as the casting machine is started. According to investigation, aluminum oxide is condensed inside the nozzle, causing the steel flow to become smaller and smaller, until the nozzle is completely blocked and no molten steel flows out. Compared with other aluminum-free steels and aluminum-containing slab steels, the cross-section of the square billet crystallizer is small, only 160*160 mm, so the water inlet inserted into the crystallizer is only about 100 mm in diameter and the inner diameter is only 30 mm. If there is something blocking the water inlet, the molten steel cannot be pulled out. Therefore, when producing aluminum-free steel, aluminum oxide will not be produced. But when producing aluminum-containing steel, once aluminum oxide blocks the water inlet, it cannot be pulled out. This will happen no matter which furnace it is, but the probability of producing aluminum oxide is highest in the first furnace.

[0003] From the perspective of cost, the quality of molten iron in blast furnace ironmaking is inversely proportional to the cost, that is, the lower the cost, the worse the quality of molten iron. When the silicon content of molten iron is 0.25% to 0.5%, the quality of molten iron is relatively good, and 0.3% to 0.4% is the best. However, the silicon content of molten iron in this range is only 0.09, which is very poor. Therefore, when making steel, the average silicon content of molten iron is 0.46% or above. This will increase the consumption of slag and oxygen blowing in steelmaking, increase the oxygen content of molten steel, increase the amount of aluminum used for deoxidation, and increase the content of aluminum oxide in molten steel. It is quite difficult to realize the direct opening of the cold heading steel head furnace.

[0004] On the other hand, the cost of adding one more transition steel in steelmaking is relatively high. Take Q195LB as an example. The amount of molten steel is 120 tons. Even if there is a customer's order, only the steelmaking processing cost is calculated. One ton of steel needs 400 yuan, and the cost of one furnace is 52,000 yuan. If there is no order, the steel in this furnace can only be used as packaging wire, which is a greater loss. If the cold heading steel head furnace can be opened directly, at least 52,000 yuan can be saved. However, if the head furnace fails to open directly, a tundish will lose 12,000 yuan, and the subsequent 2-3 furnaces of molten steel will be backlogged, and the power consumption will increase by 2,000 to 3,000 yuan per furnace.

[0005] In order to reduce costs, under the condition of poor molten iron quality caused by cost reduction in the ironmaking process, a method for directly opening the cold heading steel head furnace for smelting high silicon iron water is proposed.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a method for directly opening a furnace for smelting cold heading steel head with silicon high iron water.

[0008] The present invention is achieved in that:

[0009] In a first aspect, the present invention provides a method for directly opening a furnace for smelting cold heading steel head with silicon high iron water, comprising:

[0010] When the molten steel reaches the LF furnace, power is supplied, and slag is added to the molten steel after power supply starts;

[0011] When power is supplied and the temperature of the molten steel reaches 1590-1610℃, sample one is taken. According to the test result of sample one, the acid-soluble aluminum is adjusted to 0.054-0.056%, and the silicon is adjusted to 0.038-0.042%. After the argon gas is evenly stirred, sample two is taken. According to the result of sample two, the acid-soluble aluminum is adjusted to 0.031-0.033%, the silicon is adjusted to 0.065-0.075%, and the manganese is adjusted to 0.015-0.019%. Then the calcium wire is fed until the calcium content in the molten steel is 30ppm-55ppm. Finally, soft blowing is carried out for 12-15 minutes before leaving the station.

[0012] In an optional embodiment, the slag material includes lime, fluorite and aluminum slag;

[0013] Optionally, the slag adding method includes, by weight, sequentially adding 480-520 parts of lime, 100-120 parts of fluorite, 90-110 parts of aluminum slag, 280-320 parts of synthetic slag and 90-110 parts of aluminum slag to 120,000 parts of molten steel;

[0014] Optionally, the smelted cold heading steel is SWRCH6A.

[0015] In an optional embodiment, before the molten steel reaches the LF furnace, the process further comprises:

[0016] Add scrap steel into molten iron in the converter, then start blowing oxygen until the carbon content drops to 0.05%, then stop blowing oxygen, and then control the total amount of argon gas blown at the bottom of the converter to 660-780m 3 / h, blow high argon gas for 60-80s, then turn down the converter argon gas to 30m 3 / h, and then the steel is discharged. When discharging steel, the argon gas blowing at the bottom of the ladle is adjusted to 5-10m 3 / h, when 2 / 5 to 3 / 5 of the molten steel remains in the converter, alloy and slag are added to the molten steel;

[0017] After the steel is tapped, the ladle is moved to the argon station, where the aluminum wire is fed. After the aluminum wire is fed, the molten steel is transferred to the LF furnace for processing;

[0018] Optionally, the amount of scrap steel is controlled according to the silicon content in the molten iron. The expression of the iron-steel ratio X and the silicon Y in the molten iron is X=872.5-2.5*(Y-0.001) / 0.0005. The silicon content in the molten iron ranges from 0.15% to 0.75%. The amount of scrap steel M 2 and molten iron dosage M 1 The relationship is M 2 =M 1 *1000 / XM 1 ;

[0019] Among them, the unit of iron-steel ratio is kg / t, the unit of molten iron consumption is ton, and the unit of scrap steel consumption is ton.

[0020] In an optional embodiment, the alloy added during the steel tapping process is 500-600 parts of aluminum and iron;

[0021] Optionally, the slag added during the steel tapping process is 480 to 520 parts of lime.

[0022] In an optional embodiment, aluminum wire is fed to the molten steel at an argon station to acid-melt aluminum at 0.040% to 0.055%.

[0023] In an optional embodiment, oxygen blowing is started until the carbon content decreases to 0.05%, and after oxygen blowing is stopped, the opening of the converter dust removal valve is reduced to 30%.

[0024] In an optional embodiment, during the steel tapping process, when 3 tons of molten steel remain, the molten steel is turned off and the steel tapping is stopped.

[0025] In an optional embodiment, every 120 tons of molten steel corresponds to a calcium feeding line of 380 to 420 meters, and the line speed is 140 to 160 m / min.

[0026] In an optional embodiment, the bottom blowing argon gas is set to 50-60m 3 / h;

[0027] Optionally, the power transmission equipment is a three-phase AC electrode of a LF furnace, the power transmission gear is 4-2, and the power transmission power is 12000-15000 kilowatts / hour.

[0028] In an optional embodiment, the argon gas is stirred uniformly by: 3 / h stirring for 180-210s;

[0029] Optionally, turn down the argon gas to 10-15 m / s when sampling. 3 / h.

[0030] The present invention has the following beneficial effects:

[0031] The method provided by the present invention has the following characteristics: 1. After sampling, silicon is matched to the upper limit to reduce the production of aluminum oxide when continuous casting begins. Some silicon will compete with aluminum for oxygen to generate silicon dioxide, thereby reducing the probability of water plugging; 2. Acid-soluble aluminum is controlled according to the lower limit, which is also to reduce the burning loss of acid-soluble aluminum into aluminum oxide; 3. The calcium content of molten steel is increased to wash away the aluminum oxide inclusions produced in the nozzle to keep the nozzle unobstructed; 4. Since the calcium content of molten steel will decrease with the increase of soft blowing time, when the calcium content of molten steel is lower than 30ppm, the risk of failure to pull out is greater. In the present invention, controlling the soft blowing time within an appropriate range can prevent the problem of failure to pull out. The method provided by the present invention can realize the direct opening of the cold heading steel head furnace for smelting silicon high iron water through the above control, which can reduce the cost of steelmaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 This is the control relationship diagram of molten iron silicon and iron-steel ratio. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0035] There are many types of cold heading steel, such as SWRCH6A, SWRCH8A, SWRCH10A, SWRCH15A, SWRCH18A, etc. The numbers represent the range of carbon content in molten steel. The carbon content of SWRCH6A is 0.04%-0.06%, which is the lowest carbon content and the most difficult to control. Therefore, this case takes this type of steel as an example to provide a smelting method for this type of steel.

[0036] The method for directly opening a cold heading steel head furnace for smelting silicon high iron water provided in an embodiment of the present invention comprises:

[0037] When the molten steel reaches the LF furnace, power is supplied, and slag is added to the molten steel after power supply starts;

[0038] When power is supplied and the temperature of the molten steel reaches 1590-1610℃, sample one is taken. According to the test results of sample one, the acid-soluble aluminum is adjusted to 0.054-0.056%, and the silicon is adjusted to 0.038-0.042%. After the argon gas is stirred evenly, sample two is taken. According to the results of sample two, the acid-soluble aluminum is adjusted to 0.031-0.033%, the silicon is adjusted to 0.065-0.075%, and the manganese is adjusted to 0.015-0.019%. Then the calcium wire is fed until the calcium content in the molten steel is 30ppm-55ppm. Finally, soft blowing is carried out for 12-15 minutes before leaving the station.

[0039] The method provided by the present invention has the following characteristics: 1. After sampling, silicon is matched to the upper limit to reduce the production of aluminum oxide when continuous casting begins. Some silicon will compete with aluminum for oxygen to generate silicon dioxide, thereby reducing the probability of water plugging; 2. Acid-soluble aluminum is controlled according to the lower limit, which is also to reduce the burning loss of acid-soluble aluminum into aluminum oxide; 3. The calcium content of molten steel is increased to wash away the aluminum oxide inclusions produced in the nozzle to keep the nozzle unobstructed; 4. Since the calcium content of molten steel will decrease with the increase of soft blowing time, when the calcium content of molten steel is lower than 30ppm, the risk of failure to pull out is greater. In the present invention, controlling the soft blowing time within an appropriate range can prevent the problem of failure to pull out. The method provided by the present invention can realize the direct opening of the cold heading steel head furnace for smelting silicon high iron water through the above control, which can reduce the cost of steelmaking.

[0040] Specifically, the steelmaking method is:

[0041] S1. Treatment in converter

[0042] The iron-steel ratio is controlled according to the silicon content of molten iron. The silicon content of molten iron is 0.15% to 0.75%.

[0043] The expression of iron-steel ratio X and silicon in molten iron Y is as follows Figure 1 As shown, X=872.5-2.5*(Y-0.001) / 0.0005, the silicon content of the molten iron is in the range of 0.15-0.75%, and the amount of scrap steel M 2 and molten iron dosage M 1 The relationship is M 2 =M 1 *1000 / XM 1 ; Among them, the unit of iron-steel ratio is kg / t, the unit of molten iron consumption is tons, and the amount of scrap steel is tons. When determining the silicon content in molten iron, the amount of scrap steel can be calculated based on the above two expressions. For example, when the silicon content of molten iron is 0.6%, iron-steel ratio = 872.5-2.5*(0.006-0.001) / 0.0005 = 847.5. With an iron-steel ratio of 847.5kg / t, when the amount of molten iron is 110 tons, the scrap steel is calculated as: 110*1000 / 847.5-110 = 19.79 tons.

[0044] According to the high silicon molten iron conditions (molten iron with silicon content greater than 0.55% is called high silicon molten iron), the iron-steel ratio is controlled at 840-870kg / t. The principle is to use the high physical and chemical heat of molten iron to reduce the amount of oxygen used for converter heating, reduce the oxygen content of molten steel, and then reduce the amount of deoxidized aluminum and the total amount of aluminum oxide. If the steel-steel ratio is not within this range, for example, it is controlled at 900kg / t or higher, that is, on the original basis, more molten iron is added and more scrap steel is reduced to meet the advantages described in this principle, there will be too much excess heat, which will affect the dephosphorization in the low temperature area of ​​steelmaking. In order to meet the dephosphorization to the qualified range, 6 tons of cooling materials need to be added, which not only increases the cost, but also causes other quality problems such as high hydrogen in molten steel. However, if the iron-steel ratio is controlled at 800kg / t or lower, that is, more scrap steel is added and less molten iron is used, the advantage is that it is easy to meet the dephosphorization requirements, less or no cooling materials can be used, and quality problems such as high hydrogen content can be avoided. However, due to insufficient heat, the molten steel will be heated up after the post-blow, the oxygen content of the molten steel will be increased, and the molten steel inclusions will be increased during the deoxidation process, affecting the quality of the molten steel and causing the failure of the first furnace molten steel to be opened directly. Therefore, for high-silicon molten iron, different from the molten iron with a silicon content of 0.3%-0.5% in good conditions, the iron-steel ratio needs to be specially controlled to meet the two technical requirements of smooth dephosphorization of the molten steel and no overoxidation.

[0045] Optionally, the scrap steel is high-quality scrap steel, mainly leftovers of plates and wires.

[0046] Most steel mills agree that hot metal with a silicon content of 0.3%-0.5% is easier to smelt. Hot metal with a silicon content of more than 0.6%, especially more than 0.7%, will produce a large amount of silicon dioxide after being completely burned out in the early stage of smelting. In order to ensure dephosphorization, according to the lime addition formula, a lot of lime will need to be added to make the slag reach the alkalinity required for dephosphorization. For example, the steel requires phosphorus removal to below 0.020%, and the slag basicity needs to be 2.8 or above. The total amount of molten iron + scrap steel is 129.79 tons. When the silicon content of molten iron is 0.4%, the amount of lime added = 2.14*0.4% / 76%*2.8*129790=4093 kg. When the silicon content of molten iron is 0.6, the amount of lime added = 2.14*0.6% / 76%*2.8*129790=6139 kg. The amount of slag is very large. During the oxygen blowing process of the converter, the discharge of carbon monoxide or carbon dioxide is blocked, and the bubbles will keep pushing the slag up. It must be pushed to the outside of the furnace mouth to exhaust, causing a large amount of slag to overflow from the furnace mouth. This is why everyone thinks that molten iron with high silicon content is difficult to smelt. However, high silicon content in molten iron also has its advantages. There is a lot of excess heat, which can help reduce costs if used well. The iron-steel ratio is controlled here to target poor molten iron quality. There are very few furnaces with silicon content in molten iron between 0.3% and 0.5%, and most molten iron has silicon content above 0.6%. Therefore, it is necessary to calculate the iron-steel ratio control range based on the silicon content in the molten iron, and then calculate the amount of scrap steel to be added. Since more molten iron is used and less scrap steel is added, the amount of molten iron is larger, and the physical heat and chemical heat are higher, which can reduce the amount of oxygen blowing used to heat the converter, reduce the oxygen content of the molten steel, and thereby reduce the amount of deoxidized aluminum and the total amount of alumina.

[0047] Determine the amount of molten iron and scrap steel according to the above calculation method, then add scrap steel into the molten iron in the converter, then start blowing oxygen until the carbon content drops to 0.05%, then stop blowing oxygen, and then control the total amount of argon gas blown at the bottom of the converter to 660-780m 3 / h, blow argon gas for 60 to 80 seconds.

[0048] Optionally, the converter has six bottom blowing holes, and the argon flow rate of each hole is 110-130m 3 / h.

[0049] Here, when the carbon is removed to 0.05%, according to the carbon-oxygen product or the fixed oxygen, the oxygen content of the molten steel is about 600ppm or 0.06%. Under the action of closing the dust removal valve and opening the bottom argon gas, the pressure will change, promoting the reaction of free oxygen and carbon in the molten steel, and reducing the oxygen content while reducing the carbon content. Prepare for subsequent production. Here, if we directly remove the carbon to 0.03% by blowing oxygen, according to the carbon-oxygen product or the oxygen meter, the oxygen in the molten steel is about 1000pmm. Compared with 600ppm of oxygen, there will definitely be a lot more inclusions produced during the deoxidation process. However, if we stop blowing oxygen after removing carbon to 0.08%, and decarbonize by opening the argon gas, then according to the carbon-oxygen product, we know that the oxygen content of the molten steel is about 380ppm, and from the molecular weight of the carbon monoxide chemical formula, we know that carbon: oxygen = 12:16 = 120:160, that is, even if all the oxygen is consumed, the carbon cannot be removed to 0.03%. According to calculations, why don't we decarbonize when the carbon content is reduced to 0.06% and the oxygen content in the molten steel is around 500ppm? Theoretically, the carbon-oxygen reaction can remove 0.03% of the carbon, and the steel can be produced using an endpoint carbon of 0.03%. But in reality, it is impossible to remove so much carbon. Even if the argon stirring time is increased to 5 minutes, the carbon content cannot be reduced to such a low level. The iron oxide in the slag can only be reduced. The principle is that under atmospheric pressure, carbon and oxygen reach a state of equilibrium. If carbon and oxygen are to continue to react, the atmospheric pressure must be lowered, or the oxygen content in the molten steel must be increased to allow more excess oxygen to react with the carbon in the molten steel. Therefore, removing the carbon content to 0.05%, opening a large bottom blowing argon for stirring, and controlling the stirring time are experiences we have gained from data from multiple experiments.

[0050] S2, converter steel tapping

[0051] After blowing the argon, adjust the converter argon to 30m 3 / h direct steel tapping, argon gas blowing from the bottom of the ladle during steel tapping is 5-10m 3 / h, when 2 / 5 to 3 / 5 of the molten steel remains in the converter, add alloy and slag to the molten steel, and maintain the argon flow rate at 5 to 10m 3 / h, reduce nitrogen absorption by molten steel, turn off the molten steel 3 tons before the end of steelmaking to avoid slag.

[0052] Specifically, the alloy added during the steel tapping process is 500-600 parts of aluminum and iron;

[0053] Optionally, the slag added during the steel tapping process is 480 to 520 parts of lime.

[0054] During the steel-making process, since the oxygen in the molten steel is reduced and it is easy to absorb nitrogen, we use small bottom blowing to blow argon throughout the whole process. However, if we do not open argon blowing in order to reduce the absorption of nitrogen by the molten steel, the pores of the bottom-blown air bricks may be blocked by the molten steel after a period of time, making it impossible to blow through. On the other hand, if argon is not opened at all when slag and aluminum iron are added during the steel-making process, it will also affect the melting of the slag and the deoxidation of the aluminum iron.

[0055] Generally speaking, all steel mills are required to produce all the molten steel to reduce waste, but because this type of steel is particularly sensitive to aluminum oxide inclusions, we can only shut off the molten steel in advance to avoid slag.

[0056] At the same time, we have requirements for the ladles used in the previous furnace. Only ladles containing aluminum steel or slab steel can be used. Ladles made of semi-killed steel or screw steel cannot be used because there will be more return of oxygen and silicon, which will affect the quality of the molten steel.

[0057] S3, aluminum wire feeding

[0058] The ladle is moved to the argon station, and the molten steel leaves the station after feeding the aluminum wire at the argon station.

[0059] Optionally, the operating method and parameters for feeding aluminum wire are as follows: at a line speed of 250 to 300 meters per minute, based on the oxygen value of the argon station, deoxidize 1 ppm per meter of aluminum wire, and increase the acid-soluble aluminum by 0.001% per 5 meters, so that the acid-soluble aluminum in the molten steel is adjusted to 0.040% to 0.055%.

[0060] According to the chemical composition of the steel sample, aluminum is added to the range. If it is only added to 0.030% or less, after the molten steel arrives at the LF furnace, the slag will be green glass slag at the time of sampling, which has a very poor effect on adsorbing inclusions. The staff must add a large amount of aluminum and lime to adjust the slag back to white cream slag, which will reduce the time for the white slag to adsorb inclusions. However, if argon is used to add acid-soluble aluminum to 0.065% or more in order to make white slag in advance, the molten steel will be found to have thick slag when it is smelted in the LF furnace and sampled at the time of sampling. Fluorite needs to be added to adjust the fluidity. At the same time, the acid-soluble aluminum in the sample is high, and argon needs to be stirred to burn the acid-soluble aluminum to the qualified range, which will also increase the inclusion of aluminum oxide.

[0061] Therefore, the control range of acid-soluble aluminum in the argon station is determined through multiple practical explorations and summaries, combined with the speed of making white slag in the LF furnace process and the reduction of aluminum oxide inclusions. Within this range, the more employees can control to the upper limit, the more beneficial it is to the quality of molten steel, because the higher the acid-soluble aluminum, the easier it is to make white slag, and the less aluminum is added in the later stage of the LF furnace, the fewer fine aluminum oxide inclusions are produced.

[0062] S4, LF furnace treatment

[0063] The molten steel is transferred to the LF furnace, and power is supplied after arriving at the LF furnace. After power supply starts, slag is added to the molten steel.

[0064] Optionally, the slag material includes lime, fluorite and aluminum slag;

[0065] Optionally, the slag adding method includes, by weight, adding 480-520 parts of lime, 100-120 parts of fluorite, 90-110 parts of aluminum slag, 280-320 parts of synthetic slag and 90-110 parts of aluminum slag to 120,000 parts of molten steel in sequence.

[0066] Since only 500 kg of lime is added to the converter, there is only a thin layer of slag on the surface of the molten steel. Therefore, lime is first added to thicken the slag, and then fluorite is added to promote the melting of lime. Then aluminum slag is added to make the slag foam and accelerate melting. Then, synthetic slag is added to improve the effect of power transmission and buried arc. Finally, aluminum slag is added again to make the slag foam, prolong the slag foaming time, promote the slag melting, and quickly form white foam slag. During the power transmission process, the gas in the slag is gradually discharged through argon stirring, and white cream slag is formed. During the process of adding slag and power transmission, the bottom blowing argon is adjusted to 50-60 cubic meters / hour, and the desired slag can be formed when the power transmission time is greater than 500 seconds.

[0067] Specifically, aluminum slag is a mixture of 40% metallic aluminum and other impurities, and synthetic slag is a mixture of 50% lime + 50% bauxite, wherein lime is a mixture of 93% calcium oxide and other oxides, and bauxite is a mixture of 70% calcium oxide and other oxides.

[0068] When power is supplied and the temperature of the molten steel reaches 1590-1610℃, sample one is taken. According to the test results of sample one, the acid-soluble aluminum is adjusted to 0.054-0.056%, and the silicon is adjusted to 0.038-0.042%. After the argon gas is stirred evenly, sample two is taken. According to the results of sample two, the acid-soluble aluminum is adjusted to 0.031-0.033%, the silicon is adjusted to 0.065-0.075%, and the manganese is adjusted to 0.015-0.019%. Then the calcium wire is fed until the calcium content in the molten steel is 30ppm-55ppm. Finally, soft blowing is carried out for 12-15 minutes before leaving the station.

[0069] Optionally, every 120 tons of molten steel corresponds to a calcium feeding line of 380 to 420 meters, and a line speed of 140 to 160 m / min.

[0070] Optionally, the bottom blowing argon gas is set to 50-60m 3 / h;

[0071] Optionally, the power transmission equipment is a three-phase AC electrode of a LF furnace, the power transmission gear is 4-2, and the power transmission power is 12000-15000 kilowatts / hour.

[0072] Optionally, the argon gas is stirred uniformly by: 3 / h stirring for 180 to 210 seconds.

[0073] Optionally, turn down the argon gas to 10-15 m / s when sampling. 3 / h.

[0074] Optionally, the argon flow rate during soft blowing is 3 to 10 m 3 / h.

[0075] The above parameters are the best ranges or target values ​​we have summarized through experiments. For example, after sample 1 comes out, the acid-soluble aluminum is adjusted to 0.055%, and stirred at a specified flow rate for a specified time. In addition to the purpose of removing large inclusions, when the results of sample 2 come out, the acid-soluble aluminum is basically 0.030%-0.035%. Basically, there is no need to add aluminum to sample 2 again. However, in the actual process, some furnaces will have large differences in bottom blowing effects, test deviations and other factors, resulting in sample 2 acid-soluble aluminum not within the budget range, so it is necessary to add acid-soluble aluminum again. The control of silicon in molten steel is also the same. If silicon is not added when sample 1 comes out, it will be added when sample 2 comes out. The amount of addition will be relatively large, which will directly affect the accuracy of silicon addition. However, if sample 1 is directly adjusted to 0.07%, adding more silicon will also affect the accuracy. At the same time, there is a risk of over-adding more than the upper limit. Therefore, for the sake of stability, although the total amount only needs to be 0.07% silicon, we still choose to add it in two times. On the calcium feeding line, we have studied the speed of the calcium feeding line. The slower the calcium feeding line speed, the more calcium the molten steel will have. However, the longer the calcium feeding time, the greater the temperature drop of the molten steel. Therefore, we take quality and cost into consideration and control the line speed at 140-160m / min. At the same time, we have also studied the effect of soft blowing argon gas size and time on the final calcium content. In the specified soft blowing argon gas, argon needs to be blown for 11 minutes or more to ensure that the quality of the molten steel is 100% up to standard. Therefore, it is specified that argon blowing should be carried out for more than 12 minutes. However, during the argon blowing process, the calcium content of the molten steel is constantly decreasing. When the calcium is lower than 30ppm, there is a risk of failure if the head furnace is opened directly. Therefore, in order to avoid low calcium in the molten steel leaving the station, we stipulate that the longest soft blowing time is 15 minutes. In the 12-15 minute soft blowing time, the shorter the better.

[0076] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0077] Example 1

[0078] There are 110 tons of molten iron in the converter, and the silicon content of the molten iron is 0.6%. According to the calculation of the iron-steel ratio and the weight of the scrap steel, 19.79 tons of scrap steel are added, and then oxygen is blown to dephosphorize and decarbonize the slag. When the carbon content is decarbonized to 0.05%, oxygen blowing is stopped, and the opening of the converter dust removal valve is closed from 100% to 30%, reducing the exhaust volume. At the same time, the flow rate of argon blowing at the six bottom holes of the converter is adjusted, and 30m3 of argon is blown from each hole. 3 / h adjusted to 120m 3 / h, blow argon for 70s, then turn down the argon gas to 30m 3 / h steel output.

[0079] During the steel-making process, when 2 / 5 of the molten steel is left, add alloy and slag, the specific amount of which is 500 kg of lime and 550 kg of aluminum iron. The molten steel is turned off when there are 3 tons of molten steel left before the end of steel-making.

[0080] The molten steel is moved to the argon station to feed the aluminum wire, oxygen is determined and sampled, the oxygen value is 15.6ppm, the acid-soluble aluminum in the molten steel is 0.018%, the amount of aluminum wire is 15.6*1+(0.055%-0.018%) / 0.001%*5=200.6m, and then transferred to the LF furnace, power is supplied at gear 4, and the bottom blowing argon is 55m 3 / h, after power transmission begins, add 500kg lime, 110kg fluorite, 100kg aluminum slag, 300kg synthetic slag, and 100kg aluminum slag to the molten steel in sequence. When the temperature rises to 1600℃, take sample 1. According to the test results of sample 1, acid-soluble aluminum is adjusted to 0.055%, silicon to 0.040%, and 100m 3 / h argon gas stirring for 200s, then take sample 2. According to the result of sample 2, acid-soluble aluminum is adjusted to 0.032%, silicon is adjusted to 0.07%, and manganese is adjusted to 0.017%. Then feed calcium wire for 400 meters at a speed of 150m / min to ensure that calcium in molten steel is greater than 30ppm. 3 / h soft blowing for 13 minutes and exit the station.

[0081] Example 2

[0082] There are 110 tons of molten iron in the converter, and the silicon content of the molten iron is 0.7%. According to the empirical formula, the iron-steel ratio is calculated as 872.5-2.5*(0.007-0.001) / 0.0005=842.5kg / t. When the iron-steel ratio is 842.5kg / t, the scrap steel is added as 110*1000 / 842.5-110=20.56 tons. Then oxygen is blown to make slag for dephosphorization and decarburization. When the carbon content is decarburized to 0.05%, oxygen blowing is stopped, and the opening of the converter dust removal valve is closed from 100% to 30%, the exhaust volume is reduced, and the argon flow rate of the six bottom holes of the converter is adjusted to 30m from each hole. 3 / h adjusted to 120m 3 / h, blow argon for 70s, then turn down the argon gas to 30m 3 / h steel output.

[0083] During the steel-making process, when 3 / 5 of the molten steel is left, alloy and slag are added, with the specific amount of lime 500 kg and aluminum iron 580 kg. The molten steel is turned off when there are 3 tons of molten steel left before the end of steel-making.

[0084] The molten steel is moved to the argon station to feed the aluminum wire, oxygen is determined, and sampling is performed. The oxygen value is 3.4ppm, the acid-soluble aluminum in the molten steel is 0.027%, and the amount of aluminum wire is 3.4*1+(0.055%-0.027%) / 0.001%*5=143.4 meters. Then it is transferred to the LF furnace, and power is supplied at gear 4. The bottom blowing argon is 55m3 / h, after power transmission begins, add 500kg lime, 110kg fluorite, 100kg aluminum slag, 300kg synthetic slag, and 100kg aluminum slag to the molten steel in sequence. When the temperature rises to 1600℃, take sample 1. According to the test results of sample 1, acid-soluble aluminum is adjusted to 0.055%, silicon to 0.040%, and 100m 3 / h argon stirring for 200s, sample 2 was taken. According to the results of sample 2, the acid-soluble aluminum was adjusted to 0.033%, silicon to 0.073%, and manganese to 0.017%. Then, a calcium wire was fed for 400 meters at a speed of 140m / min to ensure that the calcium in the molten steel was greater than 30ppm. 3 / h soft blowing for 12 minutes and exit the station.

[0085] Comparative Example 1

[0086] This comparative example is basically the same as Example 1, except that: after sampling once, the acid-soluble aluminum is adjusted to 0.070%, resulting in a high acid-soluble aluminum content in the sample. A large amount of argon gas is used to stir and burn the acid-soluble aluminum, increasing the inclusions in the molten steel. Then, more lime is added to adsorb it, and more calcium wire is fed to remove it. However, if it is adjusted to 0.040%, the acid-soluble aluminum content is low, and more aluminum wire is fed to make the acid-soluble aluminum reach the qualified range. Since the amount of aluminum wire fed is large, it is necessary to increase the argon blowing time and add more lime to adsorb the inclusions.

[0087] Comparative Example 2

[0088] This comparative example is basically the same as Example 1, except that: after the secondary sampling, the acid-soluble aluminum is adjusted to 0.040%, and after the calcium feeding line and soft blowing, the finished acid-soluble aluminum can also be within the qualified range, but the higher the aluminum oxide in the molten steel, the greater the risk of failure in the first furnace pouring, because the main reason for the failure of the first furnace pouring is that the molten steel produces more aluminum oxide during the continuous casting tundish. However, if it is only adjusted to 0.028%, the risk of pouring failure is reduced, which may cause the acid-soluble aluminum content to be lower than the lower limit of the range. Even if the pouring is successful, the content is unqualified and the entire furnace is scrapped.

[0089] Comparative Example 3

[0090] This comparative example is basically the same as Example 1, and the only difference is that after one sampling, the silicon is adjusted to 0.02%. Then when the second sample comes out, the silicon in the molten steel is really only 0.02%. At that time, there is only one chance to adjust it to 0.07% in one go, which is far from the target and will affect the accuracy of silicon adjustment. If it is adjusted too little, it will affect the success of the first furnace casting. If it is adjusted too much, the entire furnace will be scrapped due to unqualified ingredients.

[0091] Comparative Example 4

[0092] This comparative example is basically the same as Example 1, except that the silicon content is adjusted to 0.05% after the secondary sampling. If the silicon content is low, although the composition is within the qualified range, the risk of failure in the first furnace pouring is increased, because this application is to increase the silicon content of molten steel and reduce the acid-soluble aluminum content, so that when the molten steel is poured into the continuous casting tundish, there will be a lot of silicon and acid-soluble aluminum competing for oxygen, generating silicon dioxide that will not block the water outlet, thereby increasing the probability of successful pouring. During the experiment, we failed 4 times, some of which were related to low silicon content.

[0093] Comparative Example 5

[0094] This comparative example is basically the same as Example 1, except that the calcium wire is fed for 200 meters, so that the calcium content in the molten steel is lower than 30ppm. In the experiment, it was found that on the basis of ensuring that silicon is matched to the upper limit (the upper limit of silicon content allowed for cold heading steel) and acid-soluble aluminum (the lower limit of acid-soluble aluminum content allowed for cold heading steel) is controlled at the lower limit, if the calcium content of the molten steel is low, although the pouring is successful, it is also easy to cause quality problems such as the rise of the tundish plug rod or the fluctuation of the molten steel level in the crystallizer. Therefore, it is necessary to control the calcium content of the molten steel not to be lower than 30ppm. However, if more calcium wire is fed to ensure the success of the pouring, for example, 600 meters of calcium wire is fed, it will also cause serious calcium erosion of the continuous casting tundish plug rod, affecting the number of continuous casting furnaces, that is, originally 20 furnaces of steel could be poured continuously, but now only 18 furnaces of steel can be poured continuously because the plug rod is severely eroded by the first furnace of molten steel.

[0095] Comparative Example 6

[0096] This comparative example is basically the same as Example 1, except that the soft blowing time is 20 minutes. The calcium line is fed at a specified speed of 400 meters, and the calcium content of the molten steel is increased to 44-47ppm. During the soft blowing process, an average of 0.6ppm of calcium is burned per minute. Therefore, the longer the soft blowing time, the lower the calcium content of the molten steel, and the greater the risk of failure in pouring.

[0097] In summary, the method for directly opening a furnace for smelting cold heading steel with silicon high-iron water provided by the present invention can realize the direct opening of a furnace for smelting cold heading steel with silicon high-iron water, and can reduce steelmaking costs.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for directly opening a furnace for smelting cold heading steel head with silicon high iron water, characterized in that: include: When the molten steel reaches the LF furnace, power is supplied, and slag is added to the molten steel after power supply starts; When power is supplied and the temperature of the molten steel reaches 1590-1610℃, sample one is taken. According to the test result of sample one, the acid-soluble aluminum is adjusted to 0.054-0.056%, and the silicon is adjusted to 0.038-0.042%. After the argon gas is evenly stirred, sample two is taken. According to the result of sample two, the acid-soluble aluminum is adjusted to 0.031-0.033%, the silicon is adjusted to 0.065-0.075%, and the manganese is adjusted to 0.015-0.019%. Then the calcium wire is fed until the calcium content in the molten steel is 30ppm-55ppm. Finally, soft blowing is carried out for 12-15 minutes before leaving the station.

2. The method according to claim 1, characterized in that The slag material includes lime, fluorite and aluminum slag; Optionally, the slag adding method includes, by weight, sequentially adding 480-520 parts of lime, 100-120 parts of fluorite, 90-110 parts of aluminum slag, 280-320 parts of synthetic slag and 90-110 parts of aluminum slag to 120,000 parts of molten steel; Optionally, the smelted cold heading steel is SWRCH6A.

3. The method according to claim 1, characterized in that Before the molten steel reaches the LF furnace, it also includes: Add scrap steel into molten iron in the converter, then start blowing oxygen until the carbon content drops to 0.05%, then stop blowing oxygen, and then control the total amount of argon gas blown at the bottom of the converter to 660-780m 3 / h, blow high argon gas for 60-80s, then turn down the converter argon gas to 30m 3 / h, and then the steel is discharged. When discharging steel, the argon gas blowing at the bottom of the ladle is adjusted to 5-10m 3 / h, when 2 / 5 to 3 / 5 of the molten steel remains in the converter, alloy and slag are added to the molten steel; After the steel is tapped, the ladle is moved to the argon station, where the aluminum wire is fed. After the aluminum wire is fed, the molten steel is transferred to the LF furnace for processing; Optionally, the amount of scrap steel is controlled according to the silicon content in the molten iron, the expression of the iron-steel ratio X and the silicon Y in the molten iron is X=872.5-2.5*(Y-0.001) / 0.0005, the silicon content in the molten iron ranges from 0.15 to 0.75%, and the relationship between the amount of scrap steel M2 and the amount of molten iron M1 is M2=M1*1000 / X-M1; Among them, the unit of iron-steel ratio is kg / t, the unit of molten iron consumption is ton, and the unit of scrap steel consumption is ton.

4. The method according to claim 3, characterized in that: The alloy added during the steel-making process is 500-600 parts of aluminum and iron; Optionally, the slag added during the steel tapping process is 480 to 520 parts of lime.

5. The method according to claim 3, characterized in that: Feed aluminum wire to the argon station to add 0.040% to 0.055% acid-melted aluminum in the molten steel.

6. The method according to claim 3, characterized in that Start oxygen blowing until the carbon content drops to 0.05%. After stopping oxygen blowing, reduce the opening of the converter dust removal valve to 30%.

7. The method according to claim 3, characterized in that During the steel-making process, when there are only 3 tons of molten steel left, turn off the molten steel and stop tapping.

8. The method according to claim 3, characterized in that Every 120 tons of molten steel corresponds to a calcium feeding line of 380 to 420 meters, with a line speed of 140 to 160 m / min.

9. The method according to claim 3, characterized in that: During the power transmission process, the bottom blowing argon gas is set to 50-60m 3 / h; Optionally, the power transmission equipment is a three-phase AC electrode of a LF furnace, the power transmission gear is 4-2, and the power transmission power is 12000-15000 kilowatts / hour.

10. The method according to claim 3, characterized in that: The method of stirring argon uniformly is: 3 / h stirring for 180-210s; Optionally, turn down the argon gas to 10-15 m / s when sampling. 3 / h.

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