Smelting method for reducing consumption of 1215MS alloy

Abstract

The invention discloses a smelting method for reducing 1215MS alloy consumption. The method comprises the following steps: controlling a proper slag amount in a converter smelting process, and adding silicon iron to remove oxygen to 40-55ppm after molten steel enters an LF (ladle furnace); due to slag tapping, the molten steel is high in oxygen property, the burning loss of silicon in the molten steel is higher than the original silicon burning loss, and more silicon manganese can be added to replace low manganese to reduce the cost.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a smelting method for reducing consumption of 1215MS alloy. Background Art

[0002] 1215MS is a low-carbon, low-silicon, high-manganese steel. In order to reduce the carbon increase of the alloy, low manganese and silicon manganese are generally used to match manganese. However, the upper limit of silicon is 0.06%, so the amount of silicon manganese is also limited. To ensure that silicon does not exceed the upper limit, silicon manganese is used to replace low manganese to reduce the cost of the alloy. Originally, 1215MS steel was added with 1250 kg of low manganese, 850 kg of silicon manganese, 1000 kg of ferrosulphur, and 500 kg of lime. At present, after the optimization of steelmaking technology, there is still room for cost reduction. For this reason, a method to reduce the consumption of 1215MS alloy is proposed. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the above technical background and provide a smelting method for reducing the consumption of 1215MS alloy.

[0004] The invention provides a smelting method for reducing the consumption of 1215MS alloy, which comprises: controlling a suitable slag amount during converter smelting, and adding ferrosilicon to remove oxygen to 40-55ppm after the molten steel arrives at the LF furnace.

[0005] The present invention has the following beneficial effects.

[0006] The present invention provides a smelting method for reducing the consumption of 1215MS alloy, which comprises: controlling the appropriate amount of slag in the converter smelting process, adding ferrosilicon to remove oxygen to 40-55ppm after the molten steel arrives at the LF furnace. Due to the slag, the oxygen property of the molten steel is strong, and the silicon burnout in the molten steel will be more than before, and more silicon manganese can be added to replace low manganese to achieve cost reduction. DETAILED DESCRIPTION

[0007] 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.

[0008] A smelting method for reducing 1215MS alloy consumption provided by an embodiment of the present invention is described in detail below.

[0009] The embodiment of the present invention provides a smelting method for reducing the consumption of low-carbon, low-silicon and high-manganese steel alloy, which includes: controlling the appropriate slag amount during converter smelting, and adding ferrosilicon to remove oxygen to 40-55ppm after the molten steel arrives at the LF furnace.

[0010] In some optional implementations, it mainly includes: using slag retention operation for converter smelting, adding scrap steel and molten iron into the converter, using an oxygen lance to ignite and melt the scrap steel on the surface of the molten iron, blowing off the foam slag at the end of the converter to obtain slag with very good fluidity, and when tapping the converter, after adding slag and alloy, using slag balls to stop the slag, and after the molten steel arrives at the LF furnace, adding a small amount of lime and ferrosilicon to remove oxygen to 40-55ppm before tapping the steel.

[0011] In some optional embodiments, converter smelting includes: adding scrap steel and high-silicon, low-temperature molten iron into the converter, and using an oxygen lance to ignite and melt the scrap steel on the surface of the molten iron.

[0012] In some optional implementations, the molten iron conditions are selected as follows: 106-110 tons of molten iron, 29-34 tons of scrap steel, 0.4%-0.75% silicon in molten iron, and 1250-1330° C. In contrast, the method of selecting high-silicon iron and low-temperature molten iron, and using less molten iron and more scrap steel, is used to reduce the slag used for dephosphorization of molten steel, and to add less or no ferrophosphorus after steelmaking. At the same time, because it is low-carbon steel, the temperature will rise very high when the converter is pulled carbon in the later stage, so it is necessary to add more scrap steel in the early stage to cool it down.

[0013] In some optional embodiments, the converter smelting adopts the slag-retaining operation as much as possible. When the slag-retaining operation is adopted, lime is not added during smelting, and 2300±100 kg of raw dolomite and 300±100 kg of magnesium balls are added. The main purpose of adding these slags is to protect the furnace, not for dephosphorization, because the phosphorus content of molten iron is generally 0.100%-0.110%, and the phosphorus content of the finished steel product is required to be 0.050%-0.090%. It can be said that without adding any slag, when the carbon content is pulled to 0.06% or below, there is enough oxygen in the molten steel to react with phosphorus to form phosphorus pentoxide, which floats into the slag, so that the phosphorus content of the molten steel is within the qualified range. It is just that after the carbon content is lowered, the oxygen content of the molten steel is high, which seriously erodes the furnace condition. Therefore, after each furnace is smelted, the slag needs to be poured, a certain amount of slag is left, and then the slag for protecting the furnace is added again to protect the furnace.

[0014] In some optional embodiments, the method of using oxygen lance ignition to melt the scrap steel on the surface of molten iron is as follows: in the early stage of converter smelting, the oxygen lance position is lowered to melt the scrap steel on the surface of molten iron, and in the later stage of converter smelting, low lance position and high oxygen pressure are used to blow carbon to remove carbon to below 0.06%, and the method of high lance position and low nitrogen pressure is used at the end of the converter to blow off the foam slag on the surface of molten iron to obtain slag with very good fluidity. The biggest drawback of this operation is that the steel slag is mixed out during steel tapping, so in order to prevent the slag from returning to phosphorus, it will not be operated in this way, but in the present invention, it is just necessary to reduce the cost by slag. If the slag is not thin, when adding slag balls in the later stage of steel tapping, it may float on the slag surface and cannot sink. On the other hand, if the slag is not thin, it is not easy to slag, and the effect of reducing the cost of alloy cannot be achieved.

[0015] In some optional embodiments, the method of using an oxygen lance to ignite the scrap steel on the surface of the molten iron is as follows: measure the zero position of the molten iron in the converter, lower the oxygen lance position to 2.2-2.4 meters from the surface of the molten iron, start to open the oxygen valve for ignition, and in the later stage of smelting, the lance position is lowered to 1.4-1.2 meters, and the oxygen pressure is increased to 0.91 MPa. According to the measurement results of the carbon content in the molten steel, carbon is then blown to remove the carbon to below 0.06%. The oxygen is turned off at the end of the converter. Before raising the oxygen lance, the end lance position of 1.4-1.2 meters is raised to 2 meters, and the oxygen blowing is changed to nitrogen blowing. The pressure is reduced from 0.91 MPa to 0.75 MPa. The method of high lance position and low nitrogen pressure is adopted to blow away the foamy slag on the surface of the molten iron and turn it into slag with very good fluidity, so as to facilitate steel tapping and slag removal.

[0016] In some optional implementations, when the converter is tapping steel, 1100 kg / furnace of silicon manganese and 1050 kg / furnace of low manganese are added, and 12-15 tons before the end of tapping, slag balls are added to control the slag amount.

[0017] When the converter is tapping steel, after adding slag and alloy, prepare the slag balls. 12-15 tons before the end of tapping, put the slag balls in. At this time, the steel flow will decrease, but because the nitrogen is blown in advance to dilute the slag at the end, there will be a phenomenon of steel slag mixing. The furnace will not be started until the molten steel is finished. In this way, the converter does not need to add lime. At the same time, due to the slag, the oxygen of the molten steel is strong, and the silicon loss in the molten steel will be more than before, so more silicon manganese can be added instead of low manganese to reduce costs. The amount of silicon manganese added is increased from 850 kg / furnace to 1100 kg / furnace, and the low manganese is reduced from 1250 kg / furnace to 1050 kg / furnace. If the slag balls are added too early, they will be washed away by the molten steel, resulting in more slag in the later stage. If they are added too late, it will also lead to insufficient slag. Therefore, 12-15 tons are added before the end of steelmaking to bring some slag into the molten steel. The amount of slag is about 300-500 kg. Due to the increase of oxidized slag, more silicon will be consumed for deoxidation. The greater the proportion of silicon manganese replacing low manganese, the lower the cost will be. It should be noted that the corrosion resistance of the slag balls produced by different manufacturers is different. The technicians can adjust the timing of addition according to the actual situation to get the desired slag amount.

[0018] In some optional implementations, after the molten steel arrives at the LF furnace, 200 kg of lime is added per furnace, and the oxygen is removed to 40-55 ppm by adding ferrosilicon through multiple oxygen determinations.

[0019] In some optional embodiments, the following steps are included: after the molten steel arrives at the LF furnace, 200 kg of lime / furnace is added to the molten steel, power is supplied until the temperature of the molten steel is greater than 1600°C, oxygen is determined, and the amount of ferrosilicon alloy is added according to the oxygen value. Thereafter, 100 cubic meters / hour of argon is used to stir for 2 minutes and then the oxygen is determined again. From the second oxygen determination and after that, the oxygen is removed to within 50 ppm before sampling. Then power is supplied to raise the temperature to 1600-1610°C, and 200 kg of lime is added during the heating process. After the sample comes out, alloy is added, and oxygen is determined after the addition. Ferrosilicon is added according to the oxygen value. If the oxygen content is higher than 55 pmm, 1 kg of silicon is used to deoxidize 1 ppm of oxygen. Adding ferrosilicon will remove the oxygen to within the range of 40-55 ppm. If the oxygen content is lower than 40 ppm, iron oxide is added to increase the oxygen to within the range of 40-55 ppm.

[0020] The present invention will be further described below in conjunction with the embodiments.

[0021] Example 1

[0022] A smelting method for reducing the consumption of low-carbon, low-silicon and high-manganese steel alloy comprises the following steps:

[0023] The composition requirements of low carbon, low silicon, high phosphorus and high sulfur 1215MS are as follows: carbon 0.04-0.07%, silicon 0-0.08%, manganese 1.25-1.38%, phosphorus 0.05-0.09%, sulfur 0.30-0.38%, oxygen 40-65ppm. Add molten iron and scrap steel into the converter, among which: molten iron conditions are selected: 106-110 tons of molten iron, 29-34 tons of scrap steel, 0.4%-0.75% silicon in molten iron, and 1250-1330℃ for molten iron.

[0024] In converter smelting, slag retention is used as much as possible. If slag retention is not used and new slag making is adopted, the molten steel will be dephosphorized and the cost of ferrophosphorus will be increased. When slag retention is used, lime is not added during smelting, but 2300 parts of raw dolomite and 300 parts of magnesium balls are added.

[0025] In the later stage of smelting, the gun position is lowered to 1.4-1.2 meters, and the oxygen pressure is increased to 0.91 MPa. You can observe the flame at the furnace mouth becoming smaller or use automatic temperature measuring instruments to see how much carbon is at the end, and then carry out additional carbon blowing to remove carbon to 0.06% or below.

[0026] When preparing to turn off the oxygen at the end of the converter, before raising the oxygen gun, raise the end grab position from 1.4-1.2 meters to 2 meters, change the oxygen blowing to nitrogen blowing, and reduce the pressure from 0.91 MPa to 0.75 MPa. Use the method of high grab position and low nitrogen pressure to blow away the foamy slag at the end of the converter and turn it into slag with very good fluidity.

[0027] When tapping, after adding slag and alloy, prepare the slag balls. 12 tons before the end of tapping, put the slag balls in. At this time, the steel flow will decrease, but because the nitrogen is blown in advance to dilute the slag, there will be a phenomenon of steel slag mixing. The furnace will not be started until the molten steel is finished. In this way, the converter does not need to add lime. At the same time, due to the slag, the molten steel has strong oxygen, and the silicon loss in the molten steel will be more than before, so more silicon manganese can be added instead of low manganese to reduce costs. The amount of silicon manganese added is increased from 850 kg / furnace to 1150 kg / furnace, and the low manganese is reduced from 1250 kg / furnace to 1020 kg / furnace.

[0028] Since slag is discharged during steelmaking in the converter, the amount of slag added can be reduced when the molten steel reaches the LF furnace, and the amount of lime is reduced from 500 kg / furnace to 200 kg / furnace. The process is carried out through multiple oxygen determinations, and ferrosilicon is added to remove oxygen to 40-55ppm.

[0029] The specific operation is to add 200 kg of lime at the station, send electricity to the temperature greater than 1600℃, set oxygen, add as much ferrosilicon as the oxygen value, that is, if the oxygen value is 90ppm, then add 90 kg of ferrosilicon, stir with 100 cubic meters / hour argon for 2 minutes and then set oxygen again. From the second oxygen setting and after that, remove the oxygen to within 50ppm, then take a sample, then send electricity to raise the temperature to 1600-1610℃, add 200 kg of lime during the heating process, and after the sample comes out, mix the alloy, and then set oxygen, add ferrosilicon according to the oxygen value. If the oxygen is still at 40-55ppm, do not add it. If it is higher, still calculate it based on 1ppm oxygen with 1 kg of silicon for deoxidation, and remove it to 50ppm. If the oxygen is low, you can use iron oxide to increase the oxygen to 45ppm.

[0030] Example 2

[0031] A smelting method for reducing the consumption of low-carbon, low-silicon and high-manganese steel alloy comprises the following steps:

[0032] The composition requirements of low carbon, low silicon, high phosphorus and high sulfur 1215MS are as follows: carbon 0.04-0.07%, silicon 0-0.08%, manganese 1.25-1.38%, phosphorus 0.05-0.09%, sulfur 0.30-0.38%, oxygen 40-65ppm. Add molten iron and scrap steel into the converter, among which: molten iron conditions are selected: 106-110 tons of molten iron, 29-34 tons of scrap steel, 0.4%-0.75% silicon in molten iron, and 1250-1330℃ for molten iron.

[0033] In converter smelting, slag retention is used as much as possible. If slag retention is not used and new slag making is adopted, the molten steel will be dephosphorized and the cost of ferrophosphorus will be increased. When slag retention is used, lime is not added during smelting, but 2300 parts of raw dolomite and 300 parts of magnesium balls are added.

[0034] In the later stage of smelting, the gun position is lowered to 1.4-1.2 meters, and the oxygen pressure is increased to 0.91 MPa. You can observe the flame at the furnace mouth becoming smaller or use automatic temperature measuring instruments to see how much carbon is at the end, and then carry out additional carbon blowing to remove carbon to 0.06% or below.

[0035] When preparing to turn off the oxygen at the end of the converter, before raising the oxygen gun, raise the end grab position from 1.4-1.2 meters to 2 meters, change the oxygen blowing to nitrogen blowing, and reduce the pressure from 0.91 MPa to 0.75 MPa. Use the method of high grab position and low nitrogen pressure to blow away the foamy slag at the end of the converter and turn it into slag with very good fluidity.

[0036] When tapping steel, after adding slag and alloy, prepare the slag balls. 13 tons before the end of tapping, put the slag balls in. At this time, the steel flow will decrease, but because the nitrogen is blown in advance to dilute the slag, there will be a phenomenon of steel slag mixing. The furnace will not be started until the molten steel is finished. In this way, the converter does not need to add lime. At the same time, due to the slag, the oxygen of the molten steel is strong, and the silicon loss in the molten steel will be more than before, so more silicon manganese can be added instead of low manganese to reduce costs. The amount of silicon manganese added is increased from 850 kg / furnace to 1120 kg / furnace, and the low manganese is reduced from 1250 kg / furnace to 1035 kg / furnace.

[0037] Since slag is discharged during steelmaking in the converter, the amount of slag added can be reduced when the molten steel reaches the LF furnace, and the amount of lime is reduced from 500 kg / furnace to 200 kg / furnace. The process is carried out through multiple oxygen determinations, and ferrosilicon is added to remove oxygen to 40-55ppm.

[0038] The specific operation is to add 200 kg of lime at the station, send electricity to the temperature greater than 1600℃, set oxygen, add as much ferrosilicon as the oxygen value, that is, if the oxygen value is 90ppm, then add 90 kg of ferrosilicon, stir with 100 cubic meters / hour argon for 2 minutes and then set oxygen again. From the second oxygen setting and after that, remove the oxygen to within 50ppm, then take a sample, then send electricity to raise the temperature to 1600-1610℃, add 200 kg of lime during the heating process, and after the sample comes out, mix the alloy, and then set oxygen, add ferrosilicon according to the oxygen value. If the oxygen is still at 40-55ppm, do not add it. If it is higher, still calculate it based on 1ppm oxygen with 1 kg of silicon for deoxidation, and remove it to 50ppm. If the oxygen is low, you can use iron oxide to increase the oxygen to 45ppm.

[0039] Example 3

[0040] A smelting method for reducing the consumption of low-carbon, low-silicon and high-manganese steel alloy comprises the following steps:

[0041] The composition requirements of low carbon, low silicon, high phosphorus and high sulfur 1215MS are as follows: carbon 0.04-0.07%, silicon 0-0.08%, manganese 1.25-1.38%, phosphorus 0.05-0.09%, sulfur 0.30-0.38%, oxygen 40-65ppm. Add molten iron and scrap steel into the converter, among which: molten iron conditions are selected: 106-110 tons of molten iron, 29-34 tons of scrap steel, 0.4%-0.75% silicon in molten iron, and 1250-1330℃ for molten iron.

[0042] In converter smelting, slag retention is used as much as possible. If slag retention is not used and new slag making is adopted, the molten steel will be dephosphorized and the cost of ferrophosphorus will be increased. When slag retention is used, lime is not added during smelting, but 2300 parts of raw dolomite and 300 parts of magnesium balls are added.

[0043] In the later stage of smelting, the gun position is lowered to 1.4-1.2 meters, and the oxygen pressure is increased to 0.91 MPa. You can observe the flame at the furnace mouth becoming smaller or use automatic temperature measuring instruments to see how much carbon is at the end, and then carry out additional carbon blowing to remove carbon to 0.06% or below.

[0044] When preparing to turn off the oxygen at the end of the converter, before raising the oxygen gun, raise the end grab position from 1.4-1.2 meters to 2 meters, change the oxygen blowing to nitrogen blowing, and reduce the pressure from 0.91 MPa to 0.75 MPa. Use the method of high grab position and low nitrogen pressure to blow away the foamy slag at the end of the converter and turn it into slag with very good fluidity.

[0045] When tapping steel, after adding slag and alloy, prepare the slag balls. 14 tons before the end of tapping, put the slag balls in. At this time, the steel flow will decrease, but because the nitrogen is blown in advance to dilute the slag, there will be a phenomenon of steel slag mixing. The furnace will not be started until the molten steel is finished. In this way, the converter does not need to add lime. At the same time, due to the slag, the oxygen of the molten steel is strong, and the silicon loss in the molten steel will be more than before, so more silicon manganese can be added instead of low manganese to reduce costs. The amount of silicon manganese added is increased from 850 kg / furnace to 1080 kg / furnace, and the low manganese is reduced from 1250 kg / furnace to 1050 kg / furnace.

[0046] Since slag is discharged during steelmaking in the converter, the amount of slag added can be reduced when the molten steel reaches the LF furnace, and the amount of lime is reduced from 500 kg / furnace to 200 kg / furnace. The process is carried out through multiple oxygen determinations, and ferrosilicon is added to remove oxygen to 40-55ppm.

[0047] The specific operation is to add 200 kg of lime at the station, send electricity to the temperature greater than 1600℃, set oxygen, add as much ferrosilicon as the oxygen value, that is, if the oxygen value is 90ppm, then add 90 kg of ferrosilicon, stir with 100 cubic meters / hour argon for 2 minutes and then set oxygen again. From the second oxygen setting and after that, remove the oxygen to within 50ppm, then take a sample, then send electricity to raise the temperature to 1600-1610℃, add 200 kg of lime during the heating process, and after the sample comes out, mix the alloy, and then set oxygen, add ferrosilicon according to the oxygen value. If the oxygen is still at 40-55ppm, do not add it. If it is higher, still calculate it based on 1ppm oxygen with 1 kg of silicon for deoxidation, and remove it to 50ppm. If the oxygen is low, you can use iron oxide to increase the oxygen to 45ppm.

[0048] Example 4

[0049] A smelting method for reducing the consumption of low-carbon, low-silicon and high-manganese steel alloy comprises the following steps:

[0050] The composition requirements of low carbon, low silicon, high phosphorus and high sulfur 1215MS are as follows: carbon 0.04-0.07%, silicon 0-0.08%, manganese 1.25-1.38%, phosphorus 0.05-0.09%, sulfur 0.30-0.38%, oxygen 40-65ppm. Add molten iron and scrap steel into the converter, among which: molten iron conditions are selected: 106-110 tons of molten iron, 29-34 tons of scrap steel, 0.4%-0.75% silicon in molten iron, and 1250-1330℃ for molten iron.

[0051] In converter smelting, slag retention is used as much as possible. If slag retention is not used and new slag making is adopted, the molten steel will be dephosphorized and the cost of ferrophosphorus will be increased. When slag retention is used, lime is not added during smelting, but 2300 parts of raw dolomite and 300 parts of magnesium balls are added.

[0052] In the later stage of smelting, the gun position is lowered to 1.4-1.2 meters, and the oxygen pressure is increased to 0.91 MPa. You can observe the flame at the furnace mouth becoming smaller or use automatic temperature measuring instruments to see how much carbon is at the end, and then carry out additional carbon blowing to remove carbon to 0.06% or below.

[0053] When preparing to turn off the oxygen at the end of the converter, before raising the oxygen gun, raise the end grab position from 1.4-1.2 meters to 2 meters, change the oxygen blowing to nitrogen blowing, and reduce the pressure from 0.91 MPa to 0.75 MPa. Use the method of high grab position and low nitrogen pressure to blow away the foamy slag at the end of the converter and turn it into slag with very good fluidity.

[0054] When tapping steel, after adding slag and alloy, prepare the slag balls. 15 tons before the end of tapping, put the slag balls in. At this time, the steel flow will decrease, but because the nitrogen is blown in advance to dilute the slag at the end, there will be a phenomenon of steel slag mixing. The furnace will not be started until the molten steel is finished. In this way, the converter does not need to add lime. At the same time, due to the slag, the oxygen of the molten steel is strong, and the silicon loss in the molten steel will be more than before, so more silicon manganese can be added instead of low manganese to reduce costs. The amount of silicon manganese added is increased from 850 kg / furnace to 1150 kg / furnace, and the amount of low manganese is reduced from 1250 kg / furnace to 1070 kg / furnace.

[0055] Since slag is discharged during steelmaking in the converter, the amount of slag added can be reduced when the molten steel reaches the LF furnace, and the amount of lime is reduced from 500 kg / furnace to 200 kg / furnace. The process is carried out through multiple oxygen determinations, and ferrosilicon is added to remove oxygen to 40-55ppm.

[0056] The specific operation is to add 200 kg of lime at the station, send electricity to the temperature greater than 1600℃, set oxygen, add as much ferrosilicon as the oxygen value, that is, if the oxygen value is 90ppm, then add 90 kg of ferrosilicon, stir with 100 cubic meters / hour argon for 2 minutes and then set oxygen again. From the second oxygen setting and after that, remove the oxygen to within 50ppm, then take a sample, then send electricity to raise the temperature to 1600-1610℃, add 200 kg of lime during the heating process, and after the sample comes out, mix the alloy, and then set oxygen, add ferrosilicon according to the oxygen value. If the oxygen is still at 40-55ppm, do not add it. If it is higher, still calculate it based on 1ppm oxygen with 1 kg of silicon for deoxidation, and remove it to 50ppm. If the oxygen is low, you can use iron oxide to increase the oxygen to 45ppm.

[0057] Comparative Example 1

[0058] 1. The composition requirements of low carbon, low silicon, high phosphorus and high sulfur 1215MS are as follows: carbon 0.04-0.07%, silicon 0-0.08%, manganese 1.25-1.38%, phosphorus 0.05-0.09%, sulfur 0.30-0.38%, oxygen 40-65ppm. Add molten iron and scrap steel into the converter, among which: molten iron conditions are selected: 106-110 tons of molten iron, 29-34 tons of scrap steel, 0.4%-0.75% silicon in molten iron, and 1250-1330℃ for molten iron.

[0059] 2. For converter smelting, slag retention is used as much as possible. If slag retention is not used and new slag is made, the molten steel will be dephosphorized and the cost of ferrophosphorus will be increased. When slag retention is used, lime is not added during smelting, but 2300 grams of raw dolomite and 300 grams of magnesium balls are added.

[0060] 3. In the later stage of smelting, the gun position is lowered to 1.4-1.2 meters, and the oxygen pressure is increased to 0.91 MPa. You can observe the flame at the furnace mouth becoming smaller or use automatic temperature measuring instruments to see how much carbon is at the end, and then carry out additional carbon blowing to remove carbon to 0.06% or below, and directly produce steel.

[0061] 4. After the steel is produced, the molten steel arrives at the LF furnace. The specific operation is to add 200 kg of lime at the station, send electricity to the temperature greater than 1600℃, set oxygen, and add as much ferrosilicon as the oxygen value. That is, if the oxygen value is 90ppm, then add 90 kg of ferrosilicon, stir with 100 cubic meters / hour argon for 2 minutes and then set oxygen. From the second oxygen setting and after that, remove the oxygen to within 50ppm, then take a sample, then send electricity to raise the temperature to 1600-1610℃, add 200 kg of lime during the heating process, and after the sample comes out, mix the alloy, and then set oxygen. Add ferrosilicon according to the oxygen value. If the oxygen is still at 40-55ppm, do not add it. If it is higher, still calculate it based on 1ppm oxygen and 1 kg of silicon for deoxidation, and remove it to 50ppm. If the oxygen is low, you can use iron oxide to increase the oxygen to 45ppm.

[0062] Comparative Example 2

[0063] The steps are similar to those in Example 1, except that after the oxygen blowing is completed, the foamy slag is blown away by blowing oxygen instead of nitrogen. The effect of removing the foamy slag is basically the same, because when the carbon is removed to 0.06%, basically no carbon monoxide is generated, and it is only a matter of time to remove the foam in the slag. Relatively speaking, oxygen costs 0.68 yuan / cubic meter and nitrogen costs 0.32 yuan / cubic meter, so the cost of using nitrogen is lower.

[0064] Why not use compressed air instead of nitrogen, which is cheaper? Because compressed air is not pure enough and contains nitrogen, oxygen and other gases and impurities, under certain concentration conditions, gas explosions will occur. Why does the oxygen we use not cause gas mixture explosions? That is because we use industrial pure oxygen, which not only has a very high oxygen content, but more importantly, has very few impurities that cause gas explosions, which are within a safe range.

[0065] Comparative Example 3

[0066] The steps are similar to those in Example 1, except that the slag balls added in the late stage of steel tapping are added in the middle stage of steel tapping to increase the amount of slag, thereby increasing the burning loss of silicon, reducing the amount of low manganese added, and reducing the alloy cost. According to theoretical calculation, the unit price of silicon manganese is 6,400 yuan / ton, and the low manganese is 11,000 yuan / ton. Silicon manganese can completely replace low manganese, and the alloy cost is the lowest. Therefore, in theory, as long as the amount of slag is sufficient, the silicon in silicon manganese can be oxidized. However, in the actual process, due to excessive slag, the LF furnace deoxidation will be delayed, leading to high oxygen in the molten steel, which will cause bubbles in the ingot and affect the quality of the molten steel.

[0067] In the experiment, we already know that adding more slag can reduce costs, so we also tried to increase the slag amount to 800 kg, so that more silicon manganese can be added instead of low manganese to reduce the alloy cost. However, during the LF furnace treatment process, there will be a phenomenon of deoxidation lag, that is, the oxygen in the slag will transfer oxygen to the molten steel more slowly, resulting in continuous deoxidation and reoxygenation throughout the refining process. The oxygen in the molten steel has been increasing, resulting in the molten steel leaving the station. Although the oxygen content at that time is qualified, oxygen is still being transferred from the slag to the molten steel. When the molten steel is poured into billets, the oxygen in the molten steel will be high in the later stage, resulting in bubbles in the billets.

[0068] In order to change the phenomenon of delayed deoxidation, we strengthened the deoxidation in the early stage of LF to ensure that the oxygen content of the molten steel was qualified. However, we found that when the slag amount exceeded a certain range, there would be more inclusions. Even if the deoxidation was done well and the problem of bubbles in the ingot was solved, other problems would still occur. For example, the liquid level of the molten steel in the continuous casting crystallizer fluctuated beyond the standard many times during the pouring process.

[0069] Therefore, considering quality and cost, it is necessary to add slag to reduce costs, but not too much slag can affect the quality of molten steel.

[0070] Comparative Example 4

[0071] The steps are similar to those in Example 1, except that: sampling is performed when the oxygen value is 80ppm, and sampling is performed when the oxygen value is not further reduced to 40-55ppm. Theoretically, the total oxygen content of the molten steel is the same, and the deoxidizer must be added early or late to remove the oxygen to the qualified range, but from the perspective of inclusion removal, it is different. First, the molten steel is oxygenated. As the temperature increases, the more oxygen is added, so the larger the area of ​​molten steel oxygenation is when the power is sent to the upper temperature range within the specified processing time. That is, when the oxygen is set at 1560℃, it will be 60ppm. When the power is continuously supplied to 1600℃, the oxygen will reach 80ppm. If the oxygen is set at 1560℃, deoxidizer is added, and the power is supplied to 1600℃, it will be found that the deoxidizer is not added accurately and it has to be added again. If the oxygen is set at 1600℃, it can be added enough at one time. The embodiment includes some abnormal furnaces. After adding ferrosilicon, the oxygen is still higher than 55ppm. At this time, deoxidation must be continued. If sampling is taken directly, the oxygen will be set and deoxidation will be carried out when sampling is taken again. During this period, the higher oxygen in the slag will reduce the basicity of the slag and reduce the function of adsorbing inclusions. Therefore, we need to deoxidize to the range of 40-55ppm as soon as possible. But why not determine the oxygen at 1560℃ and remove the oxygen within the range? Because in the process of continuing to supply power to 1600℃, the molten steel will return to oxygen. When the temperature rises to 1600℃, it will be found that there is both silicon and oxygen in the molten steel. It is difficult to calculate the amount of ferrosilicon added, which affects the accuracy of deoxidation. Why do we need to supply power to 1600℃ before determining the oxygen and taking samples? This temperature is determined according to the actual production of our factory. In the cycle specified by the LF furnace, when this type of steel uses normal A, B, and C ladles (better or normal ladle conditions), it only needs to be heated to 1600℃ after sampling. The temperature is enough. The factors affecting the accuracy of temperature measurement and abnormal temperature drop of the ladle are not excluded here. Therefore, it is required to calculate the temperature rise to 1600℃ based on the temperature measured at the station. After the actual temperature measurement determines the temperature, the temperature is raised to 1600-1610℃. In this way, the accuracy of temperature control and the accuracy of oxygen value in molten steel can be guaranteed.

[0072] The above are only preferred embodiments of the present invention and are 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 smelting method for reducing the consumption of 1215MS alloy, characterized in that: It includes: converter smelting During the process, the appropriate amount of slag is controlled. After the molten steel arrives at the LF furnace, ferrosilicon is added to remove oxygen to 40-55ppm.

2. The smelting method according to claim 1, characterized in that: Mainly include: The converter smelting adopts slag retention operation. Scrap steel and molten iron are added to the converter, and the scrap steel on the surface of the molten iron is melted by ignition of oxygen lance. The foam slag at the end of the converter is blown off to obtain slag with very good fluidity. When the converter is tapped, after adding slag and alloy, slag balls are used to stop the slag. After the molten steel reaches the LF furnace, a small amount of lime and ferrosilicon are added to remove oxygen to 40-55ppm before tapping.

3. The smelting method according to claim 2, characterized in that: Converter smelting includes: Scrap steel and high-silicon, low-temperature molten iron are added to the converter, and an oxygen lance is used to ignite the scrap steel on the surface of the molten iron.

4. The smelting method according to claim 3, characterized in that: The molten iron conditions are selected as follows: 106-110 tons of molten iron, 29-34 tons of scrap steel, 0.4%-0.75% silicon in molten iron, and 1250-1330°C of molten iron temperature.

5. The smelting method according to claim 2, characterized in that: The converter smelting should adopt slag-retaining operation as far as possible. When adopting slag-retaining operation, no lime is added during smelting, but 2300±100 kg of raw dolomite and 300±100 kg of magnesium balls are added.

6. The smelting method according to claim 2, characterized in that: The method of using an oxygen lance to ignite and melt the scrap steel on the surface of molten iron is as follows: in the early stage of converter smelting, the oxygen lance position is lowered to melt the scrap steel on the surface of molten iron; in the later stage of converter smelting, a low lance position and high oxygen pressure are used to supplement carbon blowing to remove carbon to below 0.06%; at the end of the converter, a high lance position and low nitrogen pressure method is used to blow away the foamy slag on the surface of the molten iron to obtain a slag with very good fluidity.

7. The smelting method according to claim 6, characterized in that: The method of using an oxygen lance to ignite and melt the scrap steel on the surface of molten iron is as follows: measure the zero position of the molten iron in the converter, lower the oxygen lance position to 2.2-2.4 meters from the surface of the molten iron, start to open the oxygen valve for ignition, and in the later stage of smelting, the lance position is lowered to 1.4-1.2 meters, and the oxygen pressure is increased to 0.91 MPa. According to the measurement results of the carbon content in the molten steel, carbon is then blown to remove the carbon to below 0.06%. The oxygen is turned off at the end of the converter. Before raising the oxygen lance, the end lance position of 1.4-1.2 meters is raised to 2 meters, and the oxygen blowing is changed to nitrogen blowing. The pressure is reduced from 0.91 MPa to 0.75 MPa. The method of high lance position and low nitrogen pressure is adopted to blow away the foamy slag on the surface of the molten iron and turn it into slag with very good fluidity, which is conducive to steelmaking and slag removal.

8. The smelting method according to claim 1, characterized in that: When the converter is tapping steel, 1100 kg / furnace of silicon manganese and 1050 kg / furnace of low manganese are added. 12-15 tons before the end of tapping, the slag balls are added to control the slag amount.

9. The smelting method according to claim 1, characterized in that: After the molten steel arrives at the LF furnace, 200 kg of lime is added per furnace, and the oxygen is removed to 40-55ppm by adding ferrosilicon through multiple oxygen determinations.

10. The smelting method according to claim 9, characterized in that: The following steps are involved: After the molten steel arrives at the LF furnace, add 200 kg of lime / furnace to the molten steel, send electricity until the temperature of the molten steel is greater than 1600℃, determine the oxygen, add the amount of ferrosilicon alloy according to the oxygen value, and then stir with 100 cubic meters / hour argon for 2 minutes and then determine the oxygen again. From the second oxygen determination and after that, the oxygen will be removed to within 50ppm, then take a sample, and then send electricity to raise the temperature to 1600-1610℃. Add 200 kg of lime during the heating process, and after the sample comes out, mix the alloy, and determine the oxygen after mixing. Add ferrosilicon according to the oxygen value. If the oxygen content is higher than 55pmm, calculate it based on 1kg of silicon for 1ppm oxygen for deoxidation. Adding ferrosilicon will remove the oxygen to the range of 40-55ppm. If the oxygen content is lower than 40ppm, add iron oxide to increase the oxygen to the range of 40-55ppm.