CN115323108A - Method for shortening high molten iron ratio smelting period of electric furnace - Google Patents
Method for shortening high molten iron ratio smelting period of electric furnace Download PDFInfo
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- CN115323108A CN115323108A CN202211124146.8A CN202211124146A CN115323108A CN 115323108 A CN115323108 A CN 115323108A CN 202211124146 A CN202211124146 A CN 202211124146A CN 115323108 A CN115323108 A CN 115323108A
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- C—CHEMISTRY; METALLURGY
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- C—CHEMISTRY; METALLURGY
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Abstract
The invention discloses a method for shortening the smelting period of the high molten iron ratio of an electric furnace, which adopts a furnace wall and bottom side blowing composite oxygen supply technology and an operation method of no energization of the high molten iron ratio, ensures the stability and easy control of the whole smelting process by defining a steel retention and slag retention system, improves the decarbonization, temperature rise and dephosphorization efficiency by optimizing the oxygen supply and slag formation system, effectively reduces the occurrence of the conditions of burning a gun, smelting splashing and slag drying, and achieves the purpose of shortening the smelting period of the high molten iron ratio of the electric furnace; the method realizes the electric furnace converter operation, effectively improves the production rhythm of the electric furnace high molten iron ratio smelting, and realizes the stable control of the single-furnace smelting period of the electric furnace within 37-40min under the condition that the molten iron ratio reaches more than 80%.
Description
Technical Field
The invention belongs to the technical field of steel smelting, and particularly relates to a method for shortening a high molten iron ratio smelting period of an electric furnace.
Background
With the development of the steel industry and the whitening of market competition, under the severe situation of the drastic increase of pressure in the steel industry, the optimization of the variety and structure of steel products, the improvement of the product quality and the reduction of the product cost are very important. In order to improve the productivity, improve the variety and structure, improve the product quality, reduce the cost of raw and auxiliary materials and furnace charges and meet the production requirement of high-quality steel, steel enterprises are in the way of developing or introducing advanced steel-making technology in an idea manner so as to improve the technical level of steel-making production.
The molten iron is used as charging material, so that the new process for smelting steel in an electric arc furnace is provided, the purity of the steel smelted by the molten iron is high, and the content of residual elements is very low, so that the molten iron can be used as the charging material for smelting high-quality steel in the electric arc furnace. The molten iron is used as the metal furnace charge, so that the situation of shortage of supply of the scrap steel can be relieved, meanwhile, a large amount of physical heat and chemical heat brought by the molten iron have the irreplaceable advantage of the scrap steel, and the molten iron plays an important role in shortening smelting time, reducing power consumption, diluting residual elements in the scrap steel and reducing the gas content in the steel when being used as the furnace charge.
However, in the production and smelting process of the electric furnace with high molten iron ratio, some problems exist:
(1) The proportion of the molten iron reaches more than 80 percent, the converter smelting production mode of the electric furnace is realized, the formation of a molten pool is earlier, and the oxygen supply and slagging system of the traditional full scrap steel production is used, so that the slag and steel are easy to mix and flow out, and the consumption of steel and iron materials is increased.
(2) The temperature of a molten pool rises quickly in the middle and later stages of smelting, the carbon-oxygen reaction is severe, the content of iron oxide in the slag is reduced quickly, the slag is dried back, and the dephosphorization effect and the smooth production are seriously influenced.
(3) The slag is dried back, so that molten steel is sprayed to the furnace wall and the furnace cover to form sticky steel, the normal use of furnace body equipment is seriously influenced, and the non-smelting period is prolonged.
(4) When the proportion of the molten iron reaches a certain degree, the carbon content of the molten iron is too high, the decarburization time is increased, and the smelting period is prolonged.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for shortening the smelting period of the high molten iron ratio of an electric furnace, which adopts a furnace wall + bottom side blowing composite oxygen supply technology and an operation method of no electrification of the high molten iron ratio, ensures the stability and easy control of the whole smelting process by determining a steel retention and slag retention system, improves the decarburization, temperature rise and dephosphorization efficiency by optimizing the oxygen supply and slag formation system, and effectively reduces the occurrence of the situations of a burning gun, smelting splashing and furnace slag drying, thereby achieving the purpose of shortening the smelting period of the high molten iron ratio of the electric furnace.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a method for shortening the high molten iron ratio smelting period of an electric furnace comprises the following steps:
(1) Adding furnace burden according to the proportion of 80-85 wt% of molten iron and 15-20 wt% of steel scrap; the scrap steel is firstly added into the furnace from a charging bucket, and then hot molten iron is poured into the furnace;
(2) After feeding, oxygen supply is started, and 2 furnace wall coherent oxygen guns, 2 side-blown oxygen guns and 1 furnace door oxygen gun are adopted; after smelting for 1min, opening the wall coherent oxygen lance and the side-blown oxygen lance to reduce oxygen content; after smelting for 3min, opening a middle oxygen lance for the wall coherent oxygen lance and a side-blown oxygen lance; after smelting for 5min, opening the wall coherent oxygen lance and the side blowing oxygen lance for high oxygen, and then carrying out high oxygen supply operation in the whole process; a large amount of steel scraps are not melted and accumulated in a hearth in the initial smelting stage, and high-strength oxygen supply is carried out too early, so that oxygen jet flow rebounds to burn the coherent oxygen lance and the side-blown oxygen lance easily, and the accident that the coherent oxygen lance leaks water and even steel penetrates through the furnace wall of the side-blown lance part occurs;
(3) During the period from the beginning of smelting to the addition of the first batch of lime, slag can be discharged according to the steel slag discharge amount of 6-8 Kg/t; the oxygen consumption reaches 600-800 Nm 3 The first batch of lime is added in the oxygen consumption interval, so that the first batch of lime can be effectively melted after being put into the furnace, and if the lime is added too early, the later slag condition is worsened due to the low temperature of a molten pool, so that dephosphorization is influenced, and the temperature is difficult to rise quickly; the oxygen consumption reaches 1200-1400 Nm 3 Adding a second batch of lime; if the slag is not completely melted after the second batch of lime is added, adding a third batch of lime when the temperature of molten steel in the furnace reaches 1550-1570 ℃;
(4) After the slag is completely melted, slag is discharged according to the slag amount of 4-6 Kg/t, so that the subsequent smelting is prevented from splashing, the slag does not sink over the steel tapping hole after the furnace is returned, and the sand filling operation of the steel tapping hole can be normally carried out;
(5) When the temperature of the molten steel reaches 1600-1640 ℃, the phosphorus content is lower than 0.015 percent, and the carbon content is higher than 0.06 percent, steel releasing operation is carried out.
In the step (1), the temperature of the molten iron is not lower than 1250 ℃, and the temperature of the molten iron is too low, so that the heat energy is insufficient in the smelting process, the molten steel is seriously oxidized at the smelting end point, and the smelting time is prolonged.
In the step (2), the maximum oxygen flow of a single branch of the furnace wall coherent oxygen lance is 1400Nm 3 H, the oxygen pressure is 1.12Mpa to 1.15Mpa; the maximum oxygen flow of a single branch of the side-blown oxygen lance is 600Nm 3 H, the oxygen pressure is 0.83Mpa to 0.85Mpa; maximum oxygen flow of furnace door oxygen lance is 500Nm 3 The oxygen pressure is 0.10MPa to 0.12MPa. Wherein the side-blown oxygen lance is arranged at the lower furnace bottom and is directly contacted with molten steel, and plays the roles of decarburization heating and molten pool stirring.
In the step (2), in order to improve the oxygen supply efficiency in the early stage and simultaneously avoid the accident of oxygen rebounding and burning the lance caused by the fact that the scrap steel is not melted in the early stage of smelting, the oxygen supply strength of the specific furnace wall coherent oxygen lance is as follows: after smelting for 1min, starting low oxygen 500Nm 3 H, smelting for 3min, and then starting 1000Nm of medium oxygen 3 H, after smelting for 5min, starting high oxygen 1400Nm 3 And h, performing subsequent whole-course high-oxygen supply operation.
In the step (2), in order to improve the oxygen supply efficiency in the early stage and avoid the accident of oxygen rebounding and burning the lance caused by the fact that the scrap steel is not melted in the early stage of smelting, the oxygen supply strength of the side-blown oxygen lance is as follows: starting 380Nm of hypoxia after 1min of smelting 3 H, smelting for 2min, starting medium oxygen 500Nm 3 H, starting high oxygen 600Nm after smelting for 3min 3 And h, performing the subsequent whole-course high-oxygen supply operation.
In the step (3), the addition amount of the first batch of lime is 10-12 Kg/t steel, and the addition amount can ensure the dephosphorization effect in the early stage of smelting on one hand and can ensure the effective melting of lime in the furnace on the other hand.
In the step (3), the adding amount of the second batch of lime is 6-8 Kg/t steel, and after the adding is finished, a furnace door oxygen lance is opened to carry out high-oxygen slagging operation so as to ensure that the slag in the middle smelting period has better fluidity.
In the step (3), the oxygen consumption reaches 1500-1600 Nm 3 When the oxygen supply time reaches 25-28 min, the slag is ensured to be in a good flowing state, and if the 'dry return' phenomenon occurs, the oxygen supply intensity of the coherent oxygen lance is timely adjusted from 1400Nm 3 Adjusting the/h to 1000Nm 3 And h, slagging is carried out, the furnace door oxygen lance is adjusted to a high oxygen gear for slagging operation, and the first temperature measurement sampling operation is carried out after the furnace slag is melted.
In the step (3), the adding amount of the third batch of lime is 5-6 Kg/t steel; and then, oxygen supply and temperature rise are continuously carried out on the molten steel according to the temperature rise speed of 5-8 ℃/min.
In the step (5), before steel placement, the coherent oxygen lance is adjusted to a protection gear of 150Nm 3 And h, switching the gas source of the side-blown oxygen lance from oxygen to nitrogen, and avoiding serious slag splashing in the tapping process.
No steel needs to be reserved in the 1 st furnace of the new furnace, an oxygen blowing lance at the bottom side is convenient to install, 5-10t of steel is reserved in 2-50 furnace ages, 10-15t of steel is reserved in 50-100 furnace ages, and 15-18 t of steel is reserved above 100 furnace ages, the corresponding steel reserving amount is adopted in different furnace ages, so that the stable operation in each furnace condition period can be effectively ensured, and the adverse conditions of slag splashing (too little steel is reserved), slag drying (too much steel is reserved), passive operation, prolonged smelting time and the like caused by furnace capacity change and molten steel surface fluctuation are avoided.
Compared with the prior art, the invention has the following beneficial effects:
the method realizes the converter operation of the electric furnace, effectively improves the production rhythm of the high molten iron ratio smelting of the electric furnace, and stably controls the single-furnace smelting period of the electric furnace within 37-40min under the condition that the molten iron ratio reaches more than 80%.
Drawings
FIG. 1 is a main oxygen supply lance bitmap;
FIG. 2 is a diagram of a smelting operation of the present invention.
Detailed Description
The invention provides a method for shortening a smelting period of an electric furnace with a high molten iron ratio, which comprises the following steps:
(1) Charging materials are mixed according to the proportion of 80-85 wt% of molten iron and 15-20 wt% of scrap steel; the scrap steel is firstly put into the furnace from a charging bucket, and then hot molten iron is poured into the furnace;
(2) After feeding, starting oxygen supply, and adopting 2 furnace wall coherent oxygen lances, 2 side-blown oxygen lances and 1 furnace door oxygen lance; after smelting for 1min, opening the wall coherent oxygen lance and the side-blown oxygen lance to reduce oxygen content; after smelting for 3min, opening a middle oxygen lance for the wall coherent oxygen lance and a side-blown oxygen lance; the method specifically comprises the following steps:
the oxygen supply intensity of the furnace wall coherent oxygen lance is as follows: after smelting for 1min, starting low oxygen 500Nm 3 H, smelting for 3min, and then starting 1000Nm of medium oxygen 3 H, after smelting for 5min, starting high oxygen 1400Nm 3 H, performing subsequent whole-process high-oxygen supply operation;
the oxygen supply strength of the side-blown oxygen lance is as follows: starting 380Nm of low oxygen after smelting for 1min 3 H, smelting for 2min, starting medium oxygen 500Nm 3 H, starting high oxygen 600Nm after smelting for 3min 3 H, performing subsequent whole-course high-oxygen supply operation;
(3) The oxygen consumption reaches 600-800 Nm 3 Adding a first batch of lime, wherein the adding amount of the first batch of lime is 10-12 Kg/t of steel; when the oxygen supply time reaches 18-22 min, the oxygen consumption reaches 1200-1400 Nm 3 Adding a second batch of lime, wherein the adding amount of the second batch of lime is 6-8 Kg/t of steel; oxygen consumption reaches 1600Nm 3 When the oxygen supply time reaches 25-28 min, the slag is ensured to be in a good flowing state, and if the 'dry back' phenomenon occurs, the oxygen supply intensity of the coherent oxygen lance is timely adjusted from 1400Nm 3 Adjusting the/h to 1000Nm 3 Melting slag, adjusting a furnace door oxygen lance to a high oxygen gear to perform melting operation, and performing first temperature measurement sampling operation after the slag is melted; when the temperature of the molten steel in the furnace reaches 1550-1570 ℃, adding a third batch of lime,the adding amount of the third batch of lime is 5-6 Kg/t steel;
(4) After the slag is completely melted, carrying out slag discharging operation according to the slag quantity of 4-6 Kg/t;
(5) When the temperature of the molten steel reaches 1600-1640 ℃, the phosphorus content is lower than 0.015 percent and the carbon content is higher than 0.06 percent, steel discharging operation is carried out, and the coherent oxygen lance is adjusted to a protection gear of 150Nm before steel discharging 3 The gas source of the side-blown oxygen lance is switched from oxygen to nitrogen, so that the slag is prevented from splashing seriously in the tapping process; no steel needs to be left in the 1 st furnace of the new furnace, the installation of a bottom side oxygen blowing lance is convenient, 5-10t steel is left in 2-50 furnace ages, 10-15t steel is left in 50-100 furnace ages, and 15-18 t steel is left in more than 100 furnace ages
The present invention will be described in detail with reference to examples.
Example 1
An electric arc furnace with a nominal capacity of 50 tons is used, and the electric arc furnace is provided with 2 furnace wall oxygen lances, 2 side blowing oxygen lances and one furnace door oxygen lance. The blended molten iron comprises the main components of 4.5 percent of C, si:0.468%, mn:0.378%, S:0.025%, P:0.138 percent and the temperature of molten iron is 1273 ℃; the charging amount of scrap steel is 11.4t, and the charging amount of molten iron is 43.3t; and (5) leaving steel and slag for 15t when the furnace is aged to 116.
The specific electric furnace smelting operation steps are as follows:
(1) And (4) after the furnace cover is screwed out, adding scrap steel into the material basket, then pouring hot molten iron into the material basket by using a travelling crane, and screwing back the furnace cover to start smelting.
(2) Switching the side-blown oxygen lance from nitrogen to oxygen supply, and starting the coherent oxygen lance to reduce oxygen to 500Nm when the oxygen supply time is 1min 3 H; when the oxygen supply time is 3min, the medium oxygen is started for 1000Nm 3 H; when the oxygen supply time is 5min, 1400Nm high oxygen is started 3 H is the ratio of the total weight of the catalyst to the total weight of the catalyst. Starting a side-blown oxygen lance to perform smelting for 1min, and then starting the low oxygen lance to perform 380Nm 3 H, smelting for 2min, starting medium oxygen 500Nm 3 H, starting high oxygen 600Nm after smelting for 3min 3 /h。
(3) Slag is discharged according to the slag discharge amount of 6-8 Kg/t between the beginning of smelting and the adding of the first batch of lime, and the oxygen consumption reaches 720Nm 3 When the alkalinity of original slag is obviously reduced and the slag becomes thin, 580Kg of the first lime is added, no slag is discharged before the lime is slaked, and the oxygen supply amount reaches 1300Nm 3 In time, to the furnaceAdding 380Kg of second batch of lime into the mixture until the oxygen supply reaches 1950Nm 3 When the slag is completely melted, carrying out temperature measurement and sampling for the first time, wherein the temperature of molten steel is 1545 ℃, and the sampling analysis result is C:0.563%, P:0.024 percent. And then continuously adding 350Kg of lime, continuously supplying oxygen and heating, adjusting the gear of an oxygen lance of the furnace door to a high oxygen gear during the period of time to carry out reinforced slagging operation, spraying powder and slagging after the lime in the furnace is completely dissolved, carrying out slagging operation according to the slag quantity of 4-6 Kg/t, and then carrying out secondary temperature measurement and sampling operation, wherein the temperature of molten steel is measured at 1608 ℃, and the sampling analysis result is C:0.083%, P:0.013%.
(4) And then, adjusting the coherent oxygen lance to a protection gear, and switching the side-blown oxygen lance from oxygen supply to nitrogen to finish smelting operation for steel discharge. The time from feeding to tapping is 40min, and the oxygen supply time is 36min.
Example 2
An electric arc furnace with nominal capacity of 50 tons is used, and has 2 furnace wall oxygen lances, 2 side blowing oxygen lances and one furnace door oxygen lance. The main components of the blended molten iron are C4.5%, si:0.482%, mn:0.355%, S:0.024%, P:0.138 percent and the temperature of molten iron is 1306 ℃; the charging amount of scrap steel is 12.1t, and the charging amount of molten iron is 42.4t; the furnace age is 214, and the steel and the slag are left 18t.
The specific electric furnace smelting operation steps are as follows:
(1) And (4) screwing out the furnace cover, adding scrap steel and pouring molten iron, and then screwing back the furnace cover to start smelting.
(2) Switching the side-blown oxygen lance from nitrogen to oxygen supply, and starting the coherent oxygen lance to reduce oxygen to 500Nm when the oxygen supply time is 1min 3 H; when the oxygen supply time is 3min, the medium oxygen is started to 1000Nm 3 H; when the oxygen supply time is 5min, 1400Nm high oxygen is started 3 H is used as the reference value. Starting a side-blown oxygen lance to reduce oxygen content of 380Nm after smelting for 1min 3 H, smelting for 2min, and then starting the medium oxygen of 500Nm 3 H, starting high oxygen 600Nm after smelting for 3min 3 /h。
(3) Slag is discharged according to the slag discharge amount of 6-8 Kg/t between the beginning of smelting and the feeding of the first batch of lime, and the oxygen consumption reaches 600Nm 3 When the lime is slaked, 600Kg of the first lime is added, the slag is not discharged before the lime is slaked, and the oxygen supply amount reaches 1200Nm 3 When the lime is left and right, a second batch of lime 400K is added into the furnaceg, when the oxygen supply amount reaches 1800Nm 3 The first temperature measurement and sampling are carried out, the temperature of the molten steel is measured to 1567 ℃, and the sampling analysis result is C:0.682%, P: 0.021 percent. And then, continuously adding 320Kg of lime, continuously supplying oxygen and heating, adjusting the gear of the oxygen lance of the furnace door to a high oxygen gear to perform reinforced slagging operation, after the lime in the furnace is thoroughly dissolved, spraying powder and slagging, performing slagging operation according to the slag amount of 4-6 Kg/t, performing secondary temperature measurement and sampling operation, measuring the temperature of molten steel by 1620 ℃, and obtaining a sampling analysis result C: 0.12%, P:0.013%.
(3) And then, adjusting the coherent oxygen lance to a protection gear, and switching the side-blown oxygen lance from oxygen supply to nitrogen to finish smelting operation for steel discharge. The time from feeding to tapping is 38min, and the oxygen supply time is 35min.
Comparative example 1
An electric arc furnace with a nominal capacity of 50 tons is used, and the electric arc furnace is provided with 2 furnace wall oxygen lances, 2 side blowing oxygen lances and one furnace door oxygen lance. The main components of the blended molten iron are C4.5%, si:0.436%, mn:0.375%, S:0.022%, P:0.136 percent and the temperature of molten iron is 1314 ℃; the charging amount of scrap steel is 11.9t, and the charging amount of molten iron is 42.7t; the furnace age is 207, and steel and slag are left in the furnace for 5t.
Because normal steel and slag leaving operation is not carried out, only steel and slag are left in later-stage furnace service for 5t, oxygen supply smelting is started after normal charging, because of the later-stage furnace service, the capacity of a hearth is obviously increased, and in addition, the steel and slag leaving amount is insufficient (the furnace age is 207, only 5 t), the distance between the liquid level of steel in the furnace and a coherent oxygen lance is obviously increased, the impact depth of oxygen on the molten steel is reduced in the smelting process, and the decarburization strength is reduced; and because the oxygen content of the slag surface is increased, excessive slagging is caused, the oxygen content of the slag layer is too high, and the slag layer continuously reacts violently after contacting with the molten steel surface, so that a large amount of molten steel carried by the slag is spouted out of the furnace, the smooth operation is seriously influenced, in order to inhibit the gushing of the slag, lime can be added in advance and repeatedly, the waste of a flux is caused, the loss of the molten steel is serious, the decarburization time is long, the total time from feeding to tapping is 48min, and the oxygen supply time is 42min.
Comparative example 2
An electric arc furnace with a nominal capacity of 50 tons is used, and the electric arc furnace is provided with 2 furnace wall oxygen lances, 2 side blowing oxygen lances and one furnace door oxygen lance. The main components of the blended molten iron are C4.5%, si:0.414%, mn:0.326%, S:0.024%, P:0.136 percent and the temperature of molten iron is 1289 ℃; the charging amount of scrap steel is 12.3t, and the charging amount of molten iron is 43.1t; and (4) leaving steel and slag for 15t when the furnace is 126 years old.
Because an operator quickly pursues oxygen in advance for a plurality of times at once, a high oxygen gear of the side-blowing and bundling oxygen lance is opened within 1-2 min of the oxygen supply time of the smelting, after a plurality of minutes, crackle sound frequently appears in a hearth, the temperature in the furnace stays at 1550-1570 ℃ for a long time in the later smelting period, and the temperature is difficult to rise subsequently. After smelting, the inside of the furnace is checked to find that one coherent oxygen lance leaks water, and the erosion of refractory materials near the mouth of the side-blown lance is serious, so that a concave hole is formed. And (4) subsequently blowing out to replace the water leakage coherent oxygen lance and spray repair the side blowing position.
Comparative example 3
An electric arc furnace with nominal capacity of 50 tons is used, and has 2 furnace wall oxygen lances, 2 side blowing oxygen lances and one furnace door oxygen lance. The main components of the blended molten iron are C4.5%, si:0.472%, mn:0.309%, S:0.024%, P:0.137% and the temperature of molten iron is 1278 ℃; the charging amount of scrap steel is 12.6t, and the charging amount of molten iron is 42.8t; and (4) keeping steel and slag for 15t when the furnace is 108.
The operation was carried out in the previous stage according to the oxygen supply system of example 1, but at an oxygen consumption of 450Nm 3 During the process, 600Kg of the first batch of lime is added, the alkalinity of slag in the hearth is not obviously improved after the first batch of lime is added, the slag is still thin, and then the oxygen consumption is 900Nm 3 400Kg of lime is added in the process, after short-time oxygen supply, the slag begins to be dried again, a furnace door oxygen lance is opened to carry out slag melting by high oxygen, the slag cannot be effectively melted, then, the furnace hearth is observed to find that a large amount of 'lumps' of the two batches of lime float on the molten steel surface, and the lime cannot be effectively melted to cover the molten steel surface, so that the molten steel splashes seriously in the oxygen supply process, and the smelting operation cannot be effectively carried out. The reason of the later analysis is mainly that lime in a molten pool cannot be melted in time due to the early lime adding, lumps float on the molten steel surface, and the subsequently added lime lacks the fluxing effect of molten slag, so that the subsequent lime lumps float on the molten steel surface, the slag condition is rapidly deteriorated, and no lime existsThe method carries out normal smelting. Then continuing to open the furnace door oxygen lance for high oxygen, and adjusting the coherent oxygen lance to 1000Nm 3 And h, performing reinforced slagging operation, extending into the furnace door by using a hand oxygen lance to blow oxygen and melt aiming at the lime with lumps, and melting the slag and then performing subsequent smelting operation. In the operation, due to the fact that lime is added too early, the subsequent smelting conditions are continuously worsened, so that the total time of smelting is 52min, and the oxygen supply time is 47min.
The above detailed description of the method for shortening the high iron ratio smelting period of an electric furnace with reference to the embodiments is illustrative and not restrictive, and several embodiments may be enumerated within the scope of the limitations, so that variations and modifications thereof without departing from the general concept of the present invention shall fall within the scope of the present invention.
Claims (10)
1. The method for shortening the smelting period of the electric furnace with the high molten iron ratio is characterized by comprising the following steps of:
(1) Charging materials are mixed according to the proportion of 80-85 wt% of molten iron and 15-20 wt% of scrap steel;
(2) After feeding, oxygen supply is started, and 2 furnace wall coherent oxygen guns, 2 side-blown oxygen guns and 1 furnace door oxygen gun are adopted; after smelting for 1min, opening the wall coherent oxygen lance and the side-blown oxygen lance to reduce oxygen content; after smelting for 3min, opening the wall coherent oxygen lance and the side blowing oxygen lance for medium oxygen; after smelting for 5min, opening the wall coherent oxygen lance and the side blowing oxygen lance for high oxygen, and then carrying out high oxygen supply operation in the whole process;
(3) During the period from the beginning of smelting to the addition of the first batch of lime, slag is discharged according to the slag discharge amount of 6-8 Kg/t steel; the oxygen consumption reaches 600-800 Nm 3 Adding a first batch of lime; the oxygen consumption reaches 1200-1400 Nm 3 Adding a second batch of lime; if the slag is not completely melted after the second batch of lime is added, adding a third batch of lime when the temperature of the molten steel in the furnace reaches 1550-1570 ℃;
(4) After the slag is completely melted, carrying out slag discharging operation according to the slag quantity of 4-6 Kg/t;
(5) When the temperature of the molten steel reaches 1600-1640 ℃, the phosphorus content is lower than 0.015 percent, and the carbon content is higher than 0.06 percent, steel releasing operation is carried out.
2. The method according to claim 1, wherein the temperature of the molten iron in the step (1) is not less than 1250 ℃.
3. The method of claim 1, wherein in step (2), the oxygen supply strength of the furnace wall coherent oxygen lance is as follows: after smelting for 1min, starting hypoxia 500Nm 3 H, smelting for 3min, and then starting 1000Nm of medium oxygen 3 H, after smelting for 5min, turning on high oxygen 1400Nm 3 And h, performing subsequent whole-course high-oxygen supply operation.
4. The method as claimed in claim 1, wherein in step (2), the oxygen supply strength of the side-blown lance is as follows: starting 380Nm of hypoxia after 1min of smelting 3 H, smelting for 2min, and then starting the medium oxygen of 500Nm 3 H, starting high oxygen 600Nm after smelting for 3min 3 And h, performing the subsequent whole-course high-oxygen supply operation.
5. The method of claim 1, wherein in step (3), the first batch of lime is added in an amount of 10 to 12Kg per ton of steel.
6. The method according to claim 1, wherein in step (3), the second batch of lime is added in an amount of 6 to 8Kg/t of steel.
7. The method according to claim 1, wherein in step (3), the amount of oxygen used is up to 1600Nm 3 When the oxygen supply time reaches 25-28 min, the slag is ensured to be in a good flowing state, and if the 'dry return' phenomenon occurs, the oxygen supply intensity of the coherent oxygen lance is timely adjusted from 1400Nm 3 Adjusting the/h to 1000Nm 3 And h, slagging is carried out, and the furnace door oxygen lance is adjusted to a high oxygen gear to carry out slagging operation.
8. The method according to claim 1, wherein in step (3), the third batch of lime is added in an amount of 5 to 6Kg per ton of steel.
9. The method as claimed in claim 1, wherein in step (5), the coherent oxygen lance is adjusted to a protection gear of 150Nm before tapping 3 And h, switching the gas source of the side-blown oxygen lance from oxygen to nitrogen.
10. The method as claimed in claim 1, wherein the new furnace 1 is free from steel, the steel is retained at 5-10 t at 2-50, 10-10 t at 50-100 and 15-18 t at over 100.
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