CN110387448B - Method for producing low-phosphorus special steel quickly and low in consumption by converter - Google Patents
Method for producing low-phosphorus special steel quickly and low in consumption by converter Download PDFInfo
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- CN110387448B CN110387448B CN201910763034.9A CN201910763034A CN110387448B CN 110387448 B CN110387448 B CN 110387448B CN 201910763034 A CN201910763034 A CN 201910763034A CN 110387448 B CN110387448 B CN 110387448B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
- C21C5/35—Blowing from above and through the bath
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
Abstract
The invention relates to a method for producing low-phosphorus special steel by a converter with high speed and low consumption, which further reduces the consumption of slag charge and steel charge and energy medium of single slag operation by applying the slag remaining operation in a converter double-slag method to a single slag operation mode, and simultaneously further reduces the discharge amount of waste gas and waste slag in the whole smelting process; moreover, based on the characteristics of short operation flow and convenient production organization of the single slag method, the smelting period of the specific low-phosphorus variety steel is greatly shortened, and the controllability of the production process is obviously enhanced; in addition, the operation also provides a foundation for increasing the proportion of scrap steel in the raw material structure and enhancing the applicability of the smelting method to the raw materials; the adjustment of the structure of the slag charge auxiliary material in the smelting process is more beneficial to realizing the reduction of the erosion of the furnace lining and the stability of the furnace shape, and creates positive and favorable conditions for the stable operation of all steel production processes.
Description
Technical Field
The invention relates to a method for producing low-phosphorus special steel by a converter with high speed and low consumption, belonging to the technical field of metallurgy.
Background
When a converter is used for smelting a specific steel grade, the economic effectiveness of how to realize dephosphorization is a typical problem which is particularly outstanding in converter smelting; on the other hand, under the condition that the whole steel industry is limited by resource and energy consumption and has higher and higher requirements on environment, how to realize the smelting of the converter low-phosphorus special steel with the lowest consumption obviously becomes a key point of industry attention and research, and therefore, the innovation and breakthrough of the converter smelting of the low-phosphorus special steel have long-term positive effects and are more time-efficiency urgent.
The mature processes that have been implemented in this field and the related studies that are being explored mainly include the following:
the duplex method adopts the combined operation of two converters, one converter dephosphorizes, the other converter receives the low-phosphorus molten iron from the dephosphorizing furnace for decarburization, and the combined operation of the two converters can realize the stable high dephosphorization rate of the converters, but the process needs two converters to complete the operation, and in addition, the process has the most complex production organization besides high requirement on production equipment and lacks of economy.
The double-slag method realizes efficient dephosphorization in the same converter through twice slagging in one smelting period, can further reduce the whole slag charge consumption by the characteristic of slag remaining operation, and can fully exert the advantages and the characteristics if the double-slag method is not limited by the production period. However, once the smelting period restrictions are concerned, especially the refining and continuous casting periods which are more compact at present are matched to improve the efficiency of the whole smelting process, higher requirements are put on the smelting period of the converter, and meanwhile, the reduction of the smelting period is the most direct measure for achieving the aim from the aspect of further reducing the consumption of the overall unit energy medium.
The single slag method is a converter smelting method of low-phosphorus steel with the shortest overall period and the lowest equipment requirement in all smelting modes. However, due to conventional understanding that the conventional concept has poor dephosphorization capability and low dephosphorization efficiency, the conventional concept is not generally considered as a method for smelting low-phosphorus special steel, and even if single slag is tried to be adopted for smelting the low-phosphorus special steel, the problems of obvious increase of slag consumption, obvious improvement of end-point blowing rate, poor smelting stability and the like often occur.
Disclosure of Invention
In order to overcome the defects, the invention provides a method for producing low-phosphorus special steel by a converter quickly and with low consumption. The invention applies the slag remaining operation in the converter double-slag method to the single-slag operation mode, further reduces the consumption of slag charge, steel charge and energy medium of the single-slag operation, and simultaneously further reduces the discharge amount of waste gas and waste slag in the whole smelting process; moreover, based on the characteristics of short operation flow and convenient production organization of the single slag method, the smelting period of the specific low-phosphorus variety steel is greatly shortened, and the controllability of the production process is obviously enhanced; in addition, the operation also provides a foundation for increasing the proportion of scrap steel in the raw material structure and enhancing the applicability of the smelting method to the raw materials; the adjustment of the structure of the slag charge auxiliary material in the smelting process is more beneficial to realizing the reduction of the erosion of the furnace lining and the stability of the furnace shape, and creates positive and favorable conditions for the stable operation of all steel production processes.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a method for producing low-phosphorus special steel by a converter with rapid and low consumption adopts converter top and bottom combined blowing, and comprises the following raw materials in percentage by weight: 60-75% of molten iron, 25-40% of clean scrap steel and the balance of pig iron; the method specifically comprises the following steps:
step 1, after slag splashing treatment is carried out on the slag of the previous furnace, the final slag is completely left in the converter, and then the raw materials are added into the converter for smelting, wherein the ratio of the mass amount of the raw materials to the tapping amount of the converter is 0.21 > (the mass amount of the raw materials-the tapping amount of the converter) ÷ the tapping amount of the converter is more than 0.1.
Step 2, during smelting, setting a converter bottom blowing stage and a blowing starting stage, lowering the lance position of the oxygen lance (the lance position of the oxygen lance in the invention refers to the distance between a spray head of the oxygen lance and the liquid level of a molten pool) to 1550-1650 mm, and adjusting the flow of the oxygen lance to 33000-38000 m3Adding lime and light burned dolomite after the converter is put into a gun, ignited and blown for 35-70 s, wherein the adding mass of the lime is 19-29 per thousand of the tapping amount of the converter, the adding mass of the light burned dolomite is 6.5-10 per thousand of the tapping amount of the converter, moving the oxygen lance upwards by 100-250mm after all the lime is added, and adjusting the flow of the oxygen lance to 26000-30000 m3And adding ores according to the condition of slagging in the furnace and the condition of furnace temperature for slagging and cooling, wherein the adding mass of the ores is less than or equal to 10 per thousand of the steel tapping amount. In the step, the lance position is gradually moved upwards by 100-250mm, and the flow of the oxygen lance is gradually adjusted to 26000-30000 m3The low-temperature section time in the early stage of smelting is prolonged by the methods of/h and feeding (feeding refers to the adjustment of the structure of raw materials, for example, the scrap steel ratio is increased, and ores have a certain auxiliary effect), and the like, wherein the temperature of the low-temperature section is lower than 1420 ℃, and can be further set to 1350-1420 ℃; the oxygen lance moving speed and the flow rate adjusting speed both need to meet the reaction stability in the converter.
Step 3, after the oxygen content of the smelting flue gas begins to decrease, adding lime in batches of 200-500 kg/batch, adding ore in batches of 150-250 kg/batch, adjusting the temperature and melting slag to keep the FeO content in the slag (the FeO mass content is generally maintained at 14% -17%), wherein the total adding amount of the ore in a single furnace is not more than 20% of the tapping amount of the converter; after the feeding is finished, the lance position of the oxygen lance is increased to 2100-2300 mm, when the blowing is carried out for 10 min-12 min30s, the lance position of the oxygen lance is reduced to 1700-1900 mm, and then the lance is pressed for more than 30s (namely the lance position is continuously blown for more than 30 s); lifting the lance when the blowing-on is carried out for 10min30 s-13 min, namely lifting the oxygen lance from the converter to a non-converter original position, then pouring out the converter, pouring out partial slag (the slag poured out preferably accounts for 35-60% of the total slag mass in the converter), carrying out temperature measurement sampling while pouring out the slag, and confirming that the slag meets the end point molten steel: the mass content of carbon (C) is more than or equal to 0.10 percent, and the mass content of phosphorus (P) is less than or equal to 0.008 percent, then the steel is poured out, and the end point molten steel temperature is 1585-1615 ℃. In order to effectively avoid slag discharge during converter tapping, prevent rephosphorization and prevent the increase of molten steel oxidability caused by slag discharge, the tapping adopts a double-gear slag blocking cone and a sliding plate for slag blocking.
And 4, splashing slag, and reserving all slag in the converter for smelting in the next furnace after splashing slag.
Further, the converter bottom blowing in the step 2 is of a nitrogen-argon switching type, and the set flow rate of the bottom blowing is 0.08m3T, i.e.: bottom blowing 0.08m per minute per ton of molten steel in converter3Gas, wherein the bottom blowing gas switches nitrogen into argon according to the current furnace blowing condition (namely the carbon-oxygen reaction intensity in the furnace, especially the amount of CO gas generated in the smelting process, thereby determining the capacity of bringing out the bottom blowing gas, generally performing nitrogen-argon switching before the maximum CO gas appears in the furnace) during the period when the open blowing is carried out for 8-10 min30s, performing bottom blowing argon large-flow end stirring for 30-50 s before the smelting of the converter is finished, and setting the bottom blowing flow to be 0.15m3/min.t。
The nitrogen and argon switching can be dynamic switching, argon is saved to the greatest extent on the premise of not influencing the nitrogen content at the end point, the cost of bottom blowing gas is reduced, argon can be blown in the whole process, but the cost is higher.
Preferably, the oxygen lance position during slag splashing in the step 4 is 1700 mm-1900 mm, the slag splashing time is 1min30 s-3 min, and if the slag is slightly dilute, light-burned dolomite is added before slag splashing to perform end-point slag regulation and solid slag control.
Preferably, the iron water in the raw materials comprises the following main components in percentage by weight: 4.23-5.12 wt%, Si0.21-0.92 wt%, P: 0.83-0.135%, and the temperature of molten iron is 1354-1453 ℃.
Compared with the conventional process for smelting the low-phosphorus steel in the converter, the invention has the following positive effects:
(1) the method effectively realizes the smelting of the converter with high clean scrap steel ratio, the improvement of the scrap steel ratio is not only beneficial to reducing the integral dephosphorization load of the converter smelting, but also beneficial to prolonging the smelting process, particularly the early low-temperature effective dephosphorization period, and meanwhile, the overall yield of the iron and steel materials for smelting the low-phosphorus special steel by the converter is remarkably improved, and the consumption of the iron and steel materials per ton of the steel is reduced by 25-50 kg compared with the conventional process;
(2) the recycling of the slag remained at the end point in the single slag operation mode creates special favorable conditions for ensuring the rapid slagging and slagging of the smelting process under the condition of high steel scrap ratio, improving the fluidity of the slag at the early stage of smelting, adopting low lance position and large oxygen flow for reinforced dephosphorization at the early stage of blowing, and also reduces the consumption of slag charge and the heat consumption under the high steel scrap ratio, wherein the consumption of the slag charge is reduced by 35 to 50 percent compared with the conventional process;
(3) the invention adopts the operation mode of single slag remaining of the converter, realizes low-consumption smelting of the low-phosphorus special steel converter, has more obvious advantages on production organization and smelting period, and shortens the smelting period by 5-10 min compared with the single-furnace smelting period of the conventional smelting process;
(4) the raw material structure is dynamically and flexibly adjusted according to the molten iron conditions and the slag remaining amount of each heat, so that the raw material applicability is greatly improved in the process of producing low-phosphorus special steel by using the converter;
(5) compared with the conventional process for producing the low-phosphorus steel converter, the method greatly reduces the addition of cold materials and raw materials (the raw materials mainly refer to limestone and raw dolomite) in the whole smelting process, reduces the erosion of the auxiliary materials to a furnace lining on one hand, avoids the occurrence of greatly expanding the furnace bottom on the other hand, and further enhances the furnace shape controllability in the process of smelting the low-phosphorus special steel;
(6) the end point tapping condition can simultaneously meet the end point control condition of the low-phosphorus special steel converter with C more than or equal to 0.10 percent and P less than or equal to 0.008 percent.
Detailed Description
The present invention is not limited to the following embodiments, and those skilled in the art can implement the present invention in other embodiments according to the disclosure of the present invention, or make simple changes or modifications on the design structure and idea of the present invention, and fall into the protection scope of the present invention. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The invention is described in more detail below with reference to the following examples:
example 1:
the method for producing the low-phosphorus special steel by the converter with the advantages of high speed and low consumption adopts a 120t converter (with a steel tapping amount of 120t) for top-bottom combined blowing, and comprises the following raw materials in percentage by weight: 64 percent of molten iron (the main components except iron in the molten iron are 4.79 percent by weight of C, 0.85 percent by weight of Si and 0.106 percent by weight of P, the temperature of the molten iron is 1406 ℃), and the balance is 36 percent of clean scrap steel, and the total amount of the raw materials is 129.6 t.
Step 1, after slag splashing treatment is carried out on the slag of the previous furnace, all the final slag is left in the converter, the slag is left after tapping, the slag amount is 4.2t, and the raw materials are added into the converter for smelting.
Step 2, during smelting, setting the bottom blowing of a converter, wherein the bottom blowing flow of the converter is set to be 0.08m3T, bottom blowing gas, when oxygen is blown for 9min20s, bottom blowing nitrogen is switched to bottom blowing argon. The blowing process with low lance position and large flow is adopted in the blowing stage, the lance position is controlled at 1600mm, the blowing is carried out, the flow of the oxygen lance is adjusted to 36500m3H is used as the reference value. After the lower gun is ignited and blown for 58s, lime and light-burned dolomite are added, wherein the addition amount of the lime is 2100 kg/furnace, and the addition amount of the light-burned dolomite is 1000 kg/furnace. After the batch is completely added, the gun position is gradually lifted 150mm, and the flow rate is adjusted to 28000m3H (namely, the oxygen lance is gradually moved up by 150mm under the premise of ensuring the stable reaction in the converter and preventing the adverse conditions of anti-drying, splashing and the like in the converter, and the flow is gradually adjusted to 28000m3And/h), blowing on until 20s starts within 1min, adding 200-350 kg of ore in batches, and adjusting temperature and melting slag, wherein the total addition amount of the ore at the early stage is 1000 kg.
Step 3, after the oxygen content of the smelting flue gas begins to decrease, adding slag materials in batches according to 200 kg-500 kg of lime and in batches according to 150-250 kg of limeAdding ores in batches to keep a certain FeO content in the slag to be maintained at 14% -17%, wherein the total adding amount of the secondary ores is 2.12 t; after the charging is finished, the position of the oxygen lance is increased to 2200 mm; when the blow-on proceeded for 10min45s, the bottom-blowing flow rate was adjusted to 0.15m3T, pressing the gun position to 1750mm, and pressing the gun for 35 s; lifting the lance 20s after the blowing is carried out for 11min, then, turning the converter, carrying out temperature measurement sampling, and pouring out partial slag, wherein the poured out partial slag accounts for 45% of the total slag mass in the converter, the molten steel temperature is 1602 ℃, and the ratio of C in the molten steel is: 0.13%, P: 0.007%; immediately reversing the furnace and tapping after confirming the temperature and the molten steel components, wherein double-gear tapping is adopted; the furnace is found to be slightly dilute in slag during sampling, and 300kg of light-burned dolomite is added immediately during the sampling period for end point slag solidification.
Step 4, after tapping, slag splashing is carried out by adopting a low gun position of 1400mm, and the slag splashing time is 2min15 s; after the furnace splashes slag, 5.2t of the whole slag in the furnace is left in the furnace for smelting in the next furnace.
The furnace consumption conditions are as follows: lime 23.2 kg/ton steel, the total consumption of slag charge is 31.9 kg/ton steel, the consumption of steel and iron charge is 1.109 t/ton steel, and the smelting period is 33.5 min.
The group produces a group of 10-furnace low-phosphorus special steel according to the production process, the thickness of the furnace bottom measured by a laser thickness gauge before production is 724mm, the thickness of the steel tapping surface at the slag line part of a molten pool is 721mm, after the group finishes production, the thickness of the furnace bottom measured by the laser thickness gauge is 737mm, the thickness of the steel tapping surface at the slag line part of the molten pool is 712mm, the height of the furnace bottom is kept stable, and the corrosion of a furnace body is small.
Comparative example 1:
the top and bottom combined blowing of a 120t converter is adopted, the raw materials comprise 75 wt% of molten iron (the main components except iron in the molten iron comprise 4.74% of C, 0.76% of Si and 0.99% of P, the molten iron temperature is 1392 ℃), the balance is 25% of clean scrap steel, the total amount of the raw materials is 141.2t, and no slag is left after steel tapping on a furnace.
During smelting, the bottom blowing flow of the converter is set to be 0.05m3T, switching between nitrogen and argon when blowing oxygen for 7min and 30 s. The blowing process of normal gun position and normal flow is adopted in the blowing stage, the gun position is controlled to be 1800mm, the blowing is carried out, and the flow of the oxygen lance is adjustedIs 30500m3H is used as the reference value. Lime and light-burned dolomite are added at 20s min after the lower lance point is ignited, the addition amount of lime is 3500 kg/furnace (30 kg of steel per ton, namely 30kg of steel per ton, the same applies below), and the addition amount of light-burned dolomite is 1600 kg/furnace (13 kg of steel per ton). After the batch is completely added, the gun position is gradually lifted 150mm, and the flow rate is adjusted to 26000m3H is used as the reference value. 1min20s, starting to add ores and raw dolomite in batches according to 200-350 kg/batch for slagging and temperature regulation, wherein the total adding amount of the ores at the early stage is 3200kg (26.5 kg per ton of steel), and the adding amount of the raw dolomite is 1200kg (10 kg per ton of steel). After the oxygen content of the smelting flue gas begins to decrease, adding slag materials in batches according to 200 kg-500 kg of lime, and adding ores in batches according to 200-450 kg of the slag to keep a certain FeO content, wherein the total adding amount of the secondary ores in the furnace is 6.24t (32 kg of ton steel); after the charging is finished, the position of the oxygen lance is increased to 2200 mm; reducing the oxygen supply amount to the lower limit of 23000m at 13min of 30s3H; pressing the gun position to 1750mm at the time of 15min55s, and pressing the gun for 20 s; the lance was lifted at 16min15s, then the furnace was turned down, temperature samples were taken and part of the slag was poured out, at which time the temperature of the steel was 1621 ℃, steel C: 0.12%, P: 0.014%, in order to ensure that the P content of the steel is less than 0.010, immediately putting down the gun again for point blowing, wherein the point blowing takes 1min20s, after the point blowing is finished and the gun is lifted, measuring the temperature again and sampling, wherein the temperature of the molten steel is 1632 ℃, the temperature of the molten steel C: 0.09%, P: 0.009%, immediately turning down the furnace and tapping after confirming the temperature and the molten steel components, and stopping slag by a slag stopping cone.
Slag splashing is carried out by adopting a low lance position 1750mm after tapping, and the slag splashing time is 3min37 s; after the furnace splashes slag, the slag in the furnace is completely poured into a slag ladle.
The furnace consumption conditions are as follows: 38.6kg of lime per ton of steel, total consumption of slag charge is 57.3kg per ton of steel, consumption of iron and steel materials is 1.158t per ton of steel, and the smelting period is 42.2 min.
The group produces a group of 9-furnace low-phosphorus special steel according to the production process, the thickness of the furnace bottom measured by the laser thickness gauge before production is 711mm, the thickness of the steel tapping surface at the slag line part of the molten pool is 726mm, after the group produces, the thickness of the furnace bottom measured by the laser thickness gauge is 785mm, the thickness of the steel tapping surface at the slag line part of the molten pool is 677mm, the furnace bottom is obviously expanded, and the corrosion of the furnace body is serious.
Example 2:
the top and bottom combined blowing of a 120t converter is adopted, and the raw materials comprise, by weight, 70% of molten iron (the main components except iron in the molten iron comprise 4.64% of C, 0.45% of Si and 0.121% of P, the molten iron temperature is 1352 ℃), and the balance of 27% of clean scrap steel and 3% of pig iron, wherein the total amount of the raw materials is 131.7 t.
Step 1, after slag splashing treatment is carried out on the slag of the previous furnace, all the final slag is left in the converter, the slag is left after tapping, the slag amount is 5.6t, and the raw materials are added into the converter for smelting.
Step 2, during smelting, the bottom blowing flow of the converter is set to be 0.08m3T, switching between nitrogen and argon by bottom blowing gas while blowing oxygen for 10min05 s. The blow-on stage adopts a blowing process with low lance position and large flow, the lance position is controlled at 1700mm for blow-on, and the flow of the oxygen lance is adjusted to 35000m3H is used as the reference value. Lime and light-burned dolomite are added at the time of 1min05s after the fire is ignited, the addition amount of lime is 2450 kg/furnace (ton steel is 20.5kg), and the addition amount of light-burned dolomite is 1100 kg/furnace (ton steel is 9.2 kg). After the batch is completely added, the gun position is gradually lifted 150mm, and the flow rate is adjusted to 27000m 3/h. The blowing is carried out till 35s min, 250kg of ore is added in batches, the temperature is adjusted and the slag is dissolved, and the total adding amount of the ore at the early stage is 1580kg (13.2 kg of ton steel).
Step 3, after the oxygen content of the smelting flue gas begins to decrease, adding slag materials in batches according to 200 kg-350 kg of lime, and adding ores in batches according to 200-350 kg of the slag to keep a certain FeO content (maintained at 14% -17%) in the slag, wherein the total adding amount of the secondary ores is 2.42t (20 kg of steel per ton); after the feeding is finished, the position of the oxygen lance is raised to 2150 mm; at 11min13s, the bottom-blowing flow rate was adjusted to 0.15m3T, pressing the gun down to 1800mm, and pressing the gun for 32 s; the lance was lifted at 11min45s, then the furnace was turned down, temperature samples were taken and part of the slag was poured off, at which time the temperature of the steel was 1613 ℃, steel C: 0.12%, P: 0.008 percent, immediately reversing the furnace to tap after the temperature and the molten steel components are confirmed, and adopting double gear for tapping.
Step 4, after tapping, slag splashing is carried out by adopting a low gun position of 1400mm, and the slag splashing time is 2min35 s; after the furnace splashes slag, all slag (4.9t) in the furnace is left in the furnace for smelting in the next furnace.
The furnace consumption conditions are as follows: 25.4kg of lime per ton of steel, the total consumption of slag charge is 34.2kg per ton of steel, the consumption of steel and iron charge is 1.112t per ton of steel, and the smelting period is 34.7 min.
The group produces a group of 13-furnace low-phosphorus special steel according to the production process, the thickness of the furnace bottom measured by a laser thickness gauge before production is 742mm, the thickness of the steel tapping surface at the slag line part of the molten pool is 734mm, the thickness of the furnace bottom measured by the laser thickness gauge after the group is finished is 732mm, the thickness of the steel tapping surface at the slag line part of the molten pool is 723mm, and the whole furnace type furnace condition is stable.
Comparative example 2:
the top and bottom combined blowing of a 120t converter is adopted, the weight percentage of the raw materials is 75 percent of molten iron (the main components except iron in the molten iron comprise 4.92 percent of C, 0.47 percent of Si, 0.113 percent of P, the molten iron temperature is 1367 ℃), the balance is 15 percent of clean scrap steel and 10 percent of pig iron, the total amount of the raw materials is 143.6t, and no slag is left after the steel is tapped from the converter.
During smelting, the bottom blowing flow of the converter is set to be 0.05m3T, switching between nitrogen and argon when blowing oxygen for 8min45 s. The blowing stage adopts a conventional gun position, the gun position is controlled to be 1900mm, the flow of the oxygen lance is 29000m3H is used as the reference value. After the lance is blown for 1min and 20s, lime and light-burned dolomite are added, wherein the addition amount of lime is 3850 kg/furnace (32 kg per ton of steel), and the addition amount of light-burned dolomite is 1700 kg/furnace (14.2 kg per ton of steel). After the whole batch is added, the gun position is gradually lifted by 300mm, and the flow is adjusted to 25000m3H is used as the reference value. 1min55s, adding ores and light-burned dolomite in batches according to 350-500 kg/batch, adjusting temperature and slagging, wherein the total adding amount of the ores at the early stage is 4580kg (38.2 kg per ton of steel), and the adding amount of the raw dolomite is 2550kg (21.3 kg per ton of steel). After the oxygen content of smelting flue gas begins to decrease, adding slag materials in batches according to 200 kg-350 kg of lime, and adding ores in batches according to 200-400 kg of the slag to keep a certain FeO content (maintained at 14% -17%), wherein the total adding amount of the secondary ores is 7.65t (63.5 kg per ton of steel), and simultaneously adding raw dolomite or limestone in batches according to 200-350 kg of the temperature in the furnace for adjusting the temperature; finishing feeding at 14min25s, increasing the lance position to 2300mm, and reducing the oxygen supply to lower limit 23000m3H; pressing the gun position to 1750mm at the time of 15min55s, and pressing the gun for 20 s; lifting the lance at 17min25s, and then turning down the furnaceAnd measuring temperature, sampling and pouring out partial slag, wherein the temperature of molten steel is 1641 ℃, and the ratio of molten steel C: 0.05%, P: 0.010 percent, immediately turning down the furnace to tap after confirming the temperature and the components of the molten steel, and adopting a slag blocking cone for tapping.
Slag splashing is carried out by adopting a low lance position of 1400mm after tapping, and the slag splashing time is 3min55 s; after the furnace splashes slag, the slag in the furnace is completely poured into a slag bag.
The furnace consumption conditions are as follows: 43.3kg of lime per ton of steel, total consumption of slag charge of 62.7kg per ton of steel, consumption of steel and iron charge of 1.162t per ton of steel and smelting period of 39.2 min.
The group produces a group of 11-furnace low-phosphorus clean steel according to the production process, the thickness of the furnace bottom measured by a laser thickness gauge before production is 704mm, and the thickness of the steel tapping surface at the slag line part of a molten pool is 717 mm. After the group of production is finished, the thickness of the furnace bottom measured by the laser thickness gauge is 822mm, the thickness of the steel tapping surface at the slag line part of the molten pool is 612mm, the furnace bottom is obviously increased, and the slag line part is seriously corroded.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (6)
1. A method for producing low-phosphorus special steel by a converter with rapid and low consumption is characterized by comprising the following steps: the converter top and bottom composite blowing is adopted, and the raw materials comprise the following components in percentage by weight: 60-75% of molten iron, 25-40% of clean scrap steel and the balance of pig iron; the method specifically comprises the following steps:
step 1, after slag splashing treatment is carried out on the slag of the previous furnace, all the final slag is left in the converter, and then the raw materials are added into the converter for smelting, wherein the ratio of the mass amount of the raw materials to the tapping amount of the converter is 0.21 > (the mass amount of the raw materials-the tapping amount of the converter) ÷ the tapping amount of the converter is more than 0.1;
step 2, during smelting, setting bottom blowing of a converter, and during an open blowing stage, lowering the position of an oxygen lance to 1550-1650 mm, and adjusting the flow of the oxygen lance to 33000-38000 m3And h, starting to add lime and light-burned dolomite after the converter is put into a gun, ignited and blown for 35-70 s, wherein the mass of the added lime is 19-29 per thousand of the steel tapping amount of the converter, and the light-burned dolomite is lightThe adding mass of the calcined dolomite is 6.5-10 per thousand of the tapping amount of the converter, the oxygen lance is moved upwards by 100-250mm after the dolomite is completely added, and the flow of the oxygen lance is adjusted to 26000-30000 m3Adding ores according to the condition of slagging in the furnace and the condition of furnace temperature for slagging and cooling, wherein the adding mass of the ores is less than or equal to 10 per thousand of the steel tapping amount; the speed of moving the oxygen lance upwards and the speed of flow adjustment both need to meet the reaction stability in the converter;
step 3, after the oxygen content of the smelting flue gas begins to decrease, adding lime in batches of 200 kg-500 kg/batch, adding ore in batches of 150-250 kg/batch, and performing temperature adjustment and slagging to keep the FeO content in the slag at 14% -17%, wherein the total adding amount of the ore in a single furnace is not more than 20 per thousand of the tapping amount of the converter; after the feeding is finished, the lance position of the oxygen lance is increased to 2100-2300 mm, when the blowing is carried out for 10 min-12 min30s, the lance position of the oxygen lance is reduced to 1700-1900 mm, and then the lance is pressed for more than 30 s; lifting the gun when the blowing is carried out for 10min30 s-13 min, then pouring out the furnace, pouring out partial slag, carrying out temperature measurement sampling while pouring out the slag, and confirming that the end point of the slag meets the requirements in molten steel: pouring and tapping after the requirements that the mass content of carbon is more than or equal to 0.10 percent and the mass content of phosphorus is less than or equal to 0.008 percent are met, and the end point molten steel temperature is 1585-1615 ℃;
and 4, splashing slag, and reserving all slag in the converter for smelting in the next furnace after splashing slag.
2. The method for producing the special steel with low phosphorus content by the converter in the fast and low consumption mode according to claim 1, is characterized in that: the converter bottom blowing in the step 2 is of a nitrogen-argon switching type, and the set flow rate of the bottom blowing is 0.08m3T, and performing bottom blowing argon gas large flow end stirring for 30-50 s before the smelting of the converter is finished, wherein the bottom blowing flow is set to be 0.15m3/min.t。
3. The method for producing the special steel with low phosphorus content by the converter in the fast and low consumption mode according to claim 1, is characterized in that: and 3, the slag poured out in the step 3 accounts for 35-60% of the total mass of the slag in the converter.
4. The method for producing the special steel with low phosphorus content by the converter in the fast and low consumption mode according to claim 1, is characterized in that: and 3, tapping steel in the step 3, namely, slag blocking by using a double-gear slag blocking cone and a sliding plate.
5. The method for producing the special steel with low phosphorus content by the converter in the fast and low consumption mode according to claim 1, is characterized in that: and 4, during slag splashing in the step 4, the lance position of the oxygen lance is 1700 mm-1900 mm, the slag splashing time is 1min, 30 s-3 min, and if the slag is slightly dilute, light-burned dolomite is added before slag splashing to perform end-point slag regulation and solid slag control.
6. The method for producing the special steel with low phosphorus content by the converter in the fast and low consumption mode according to claim 1, is characterized in that: the iron-removing main components of the molten iron in the raw materials are C: 4.23-5.12 wt%, Si0.21-0.92 wt%, P: 0.83-0.135%, and the temperature of molten iron is 1354-1453 ℃.
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| CN111363889B (en) * | 2020-03-20 | 2021-10-01 | 中天钢铁集团有限公司 | Efficient phosphorus removal method for combined blown converter |
| CN111926139B (en) * | 2020-08-27 | 2021-06-29 | 北京科技大学 | Method for prolonging service life of converter lining during production of low-carbon low-phosphorus steel |
| CN112575137B (en) * | 2020-10-26 | 2022-03-25 | 邯郸钢铁集团有限责任公司 | Method for direct tapping during high-speed rail steel converter smelting |
| CN113201621B (en) * | 2021-05-19 | 2022-06-14 | 宝武集团鄂城钢铁有限公司 | Low-iron-loss-mode slag-remaining single-slag smelting operation method for converter |
| CN114438276B (en) * | 2022-02-11 | 2022-08-09 | 山东钢铁集团永锋临港有限公司 | Method for shortening smelting period of converter |
| CN114774621B (en) * | 2022-03-31 | 2023-03-28 | 宝武集团鄂城钢铁有限公司 | Extremely-low-cost converter smelting production method for deformed steel bar |
| CN114774614A (en) * | 2022-04-14 | 2022-07-22 | 首钢集团有限公司 | Converter steelmaking method |
| CN115466903A (en) * | 2022-07-13 | 2022-12-13 | 海峡(晋江)伞业科技创新中心有限公司 | High-strength special steel and production process thereof |
| CN115323098B (en) * | 2022-07-21 | 2023-08-22 | 北京科技大学 | High scrap ratio converter smelting process for producing high grade steel |
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