CN114774621A - Extremely-low-cost converter smelting production method for deformed steel bar - Google Patents
Extremely-low-cost converter smelting production method for deformed steel bar Download PDFInfo
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- CN114774621A CN114774621A CN202210332512.2A CN202210332512A CN114774621A CN 114774621 A CN114774621 A CN 114774621A CN 202210332512 A CN202210332512 A CN 202210332512A CN 114774621 A CN114774621 A CN 114774621A
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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
- 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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
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Abstract
The invention relates to a method for smelting and producing deformed steel bar with extremely low cost by a converter, which promotes the quick melting of scrap steel at the initial stage of smelting under the condition that the ratio of the scrap steel entering the converter is more than or equal to 30 percent, solves the adverse effect of the appearance of scrap steel piles on smelting, and realizes slag retention operation and low alkalinity (CaO/SiO) in the smelting process2The range is 2.0-2.5), the ultralow process cost control is realized through low lime consumption (less than or equal to 26 kg/t), at the smelting end point, on one hand, the carbon content of the molten steel is controlled within a proper range, the oxidability of furnace slag and the molten steel is reduced, the problem that the bubbling of low-alkalinity slag at the smelting end point with higher carbon content is serious and the tapping is influenced is solved through top blowing of nitrogen, and meanwhile, nitrogen is effectively added to the molten steel under the condition of lower oxidability of the molten steel, so that the nitrogen content of the molten steel before tapping reaches 30-50 ppm, and the nitrogen content reaches 40-70 ppm after the treatment of an argon station is finished, thereby providing a good foundation for the strengthening effect after subsequent microalloying.
Description
Technical Field
The invention relates to the technical field of ferrous metallurgy and converter smelting, in particular to a converter smelting production method of deformed steel bar with extremely low cost.
Background
At present, the screw-thread steel mainly of HRB400E series is the single steel grade with the largest domestic yield. From the end of 2018, the novel national standard GB/T1499.2-2018 is completely executed by the deformed steel bar, and in order to achieve the tensile strength and the metallographic structure required by the national standard without strong cooling, a certain amount of V, Nb or Ti and the like must be added in the metallurgical process for microalloying, so that the quality of the deformed steel bar is greatly promoted, and the manufacturing cost of the deformed steel bar is obviously increased.
From the converter smelting process section, decarburization, temperature rise, dephosphorization, sulfur control and the like are core tasks. The process has the advantages that the iron material cost is reduced, the slag charge consumption is reduced, the dephosphorization efficiency is improved at the same time, the process is effectively reduced, when V, VN and Ti are added into the deformed steel bar molten steel for alloying, N in the molten steel can promote V, Ti to be separated out in forms of VN, TiN, TiCN and the like in the molten steel solidification process, the separation strengthening effect which is more powerful than that of V, Ti simple substances is formed, the strength of finished steel products is obviously improved under the same condition, the use amount of the two alloys is reduced, and the production cost is further reduced. As a common steel, the production rhythm is fast, the N content at the converter low-carbon tapping and high-oxidizability smelting end point is generally 10-20 ppm, the time of the alloying and uniformly mixing process in an argon station and the LF refining process (part of deformed steel bar production enterprises do not equip LF refining equipment) is relatively short, the nitrogen increasing amount is relatively limited, the nitrogen content of a finished product is 40-60 ppm under the condition of not adding a nitralloy, the nitrogen content generally does not exceed 80ppm, and if the nitrogen content of the smelting end point N content of 10-20 ppm is stably increased to a higher level during converter smelting, the nitrogen content of the finished product is correspondingly increased, so that the strengthening effect of the microalloy elements is better exerted, and the production cost is further reduced.
The patent with application number CN201510308609.X introduces a smelting method for adding less slag charge into a converter, and the smelting method adopts a single slag method to operate, and controls the Si content of molten iron fed into the converter to be less than or equal to 0.7 percent and the P content to be less than or equal to 0.12 percent; the method adopts a smelting model with less slag charge to control the addition of auxiliary materials, realizes the aims of lime consumption less than 20kg/t and total slag charge less than 70kg/t through process optimization control, and simultaneously has the end point phosphorus content less than or equal to 0.009 percent. In addition, for example, a steelmaking method of semisteel steelmaking double-slag remaining slag disclosed in patent No. CN201210544071.9, a smelting method of ultra-low phosphorus steel disclosed in patent No. CN201510548481.4 and the like are all smelting by adopting a double-slag method, and the purpose of smelting ultra-low phosphorus is also high, which is different from the smelting target of deformed steel.
Disclosure of Invention
The invention aims to provide a method for smelting and producing deformed steel bar in a converter with extremely low cost, which promotes the rapid melting of scrap steel in the initial smelting stage under the condition that the charging scrap steel ratio is more than or equal to 30 percent, and solves the adverse effect of scrap steel stacking on smelting. In smelting, the slag retention operation and the low alkalinity (CaO/SiO)2The range is 2.0-2.5), and the ultralow process cost control is realized by low lime consumption (less than or equal to 26 kg/t).
The invention relates to a smelting production method of an extremely low-cost deformed steel bar converter, which specifically comprises the following steps:
(1) raw material requirements
The molten iron amount is 96-105 t, the phosphorus content of the molten iron is less than or equal to 0.15%, the silicon content of the molten iron is 0.3-0.6%, the molten iron is desulfurized by adopting KR pretreatment, the sulfur content of the desulfurized molten iron is less than or equal to 50ppm, and the temperature of the molten iron before being added into the converter is more than or equal to 1300 ℃;
(2) heat balance
A slag remaining operation system is implemented, the smelting in the last furnace is completed, the tapping is finished, 40-50% of the total slag is left, the furnace body is shaken right, and the smelting in the next furnace is prepared; preheating scrap steel to 600-700 ℃ in advance, taking the temperature of molten iron entering a furnace as 1300 ℃ and the silicon content of the molten iron as the reference, and adding the reference amount of the scrap steel as 20% of the amount of the molten iron, wherein on the basis, when the temperature of the molten iron rises by 10 ℃, the amount of the scrap steel is increased by 1.2-1.5 t correspondingly, when the silicon content of the molten iron rises by 0.1% correspondingly, the amount of the scrap steel is increased by 1.8-2 t correspondingly, but the upper limit of the total amount of metal materials in the furnace is 145 t;
(3) loading operation
After the last furnace is smelted, slag is left, slag is splashed and protected, the furnace body is tilted, scrap steel is firstly loaded into the furnace, molten iron is added, then the furnace body is tilted in the opposite direction for one time, then the furnace body is tilted, the scrap steel is guaranteed to be distributed in a molten pool basically and uniformly, the scrap steel is prevented from being accumulated on one side in the furnace, and at the moment, the scrap steel has a central piling phenomenon in the furnace, namely the top of a scrap steel pile exceeds the liquid level of the molten pool;
(4) smelting process
After the converter body is shaken right, a 5+1 hole spray head structure oxygen lance is used for directly blowing, the 5+1 hole spray head structure oxygen lance is provided with a central hole and five peripheral holes surrounding the central hole, the total jet flow of the oxygen lance is more concentrated due to the existence of the central hole, the oxygen lance better acts on the middle part of the surface of a molten pool, the oxygen lance has obvious effects on quick melting of piled waste steel and uniform mixing of the upper part and the lower part of the molten pool, the initial lance position is controlled to be 3-3.5 m, and the oxygen supply intensity is 2.8-3.2 Nm3At/t.min, the higher lance position can prevent the contact damage of the oxygen lance nozzle and the high-piled non-molten waste steel on one hand, and can improve the secondary combustion rate of oxygen on the other hand, and CO in a furnace gas analysis system are analyzed2The proportion is known, the secondary combustion rate can reach 20-30%, the rapid temperature rise in the furnace is facilitated, the lance position is gradually reduced after blowing is started, when the time is 2min, the lance position is reduced to 2-2.4 m, the blowing and lance lifting are stopped, the first batch of active lime 1.5-1.8 t and light-burned dolomite 0.8-1 t (CaO content is about 40%, MgO content is about 30%) are added, the oxygen lance with a uniformly distributed nozzle structure is immediately put down from the top of the furnace and 5 holes are uniformly distributed, the lance position is 1.8m, the oxygen supply intensity is kept at 3.2-3.6 Nm3Carrying out high-intensity blowing at the time of 5-6 min, transferring to a decarburization reaction stage, quickly filling foamed slag into the furnace, adding 1.8-2.1 t of second batch of active lime and 0.4-0.6 t of light-burned dolomite, and adjusting the gun position to 1.5m of solidSetting the value, and if the slag returns to dryness in 7-15 min, adding 0.2-0.6 t of iron ore for slag regulation by 1-2 times, and adding no other slag-making materials such as active lime, dolomite and the like, or adding no slag-making material if no abnormal condition exists; controlling a smelting end point C of the converter according to the range of 0.06-0.10%, obtaining the total oxygen supply in the whole process through an empirical calculation formula, detecting the content of the molten steel C and the temperature T of the molten steel through a TSO sublance probe after the oxygen supply reaches a target value, wherein the content of the molten steel C and the temperature T of the molten steel are detected, the content of FeO is high due to low alkalinity of furnace slag, the total foaming of the furnace slag is still serious, the steel tapping is not facilitated at the moment, if the measured temperature of the molten steel is more than or equal to 1600 ℃, rapidly supplying gas to an oxygen lance and replacing the oxygen lance with nitrogen, adjusting the lance position to 2-2.4 m, and adjusting the gas supply intensity to 2.4-2.8 Nm3And/t.min, the high-lance-position nitrogen jet can blow foam in the slag to break the foam so as to convert a foam slag layer into a liquid slag layer, and on the other hand, because the target C content of the molten steel at the end point is higher, the O content of the molten steel is in the range of 300-450 ppm, the oxidability is not strong, the high-speed nitrogen jet can realize mass transfer to a molten pool through a gas-slag-liquid or gas-liquid interface, the molten pool is rapidly increased in nitrogen, the top-blowing nitrogen time is 2-3 min, the cooling range is 5-10 ℃, the tapping temperature is controlled according to 1590-1620 ℃, the P content of the molten steel is less than or equal to 0.022%, and the S content is less than or equal to 0.012%. Then, normal tapping and alloying are carried out, and the smelting process is finished; and (3) the content of liquid nitrogen of steel at the smelting end point is 30-50 ppm, and after steel tapping is alloyed and argon gas is blown to the bottom of an argon station and is uniformly mixed, the content of nitrogen of molten steel reaches 40-70 ppm.
The smelting process also comprises the whole process of bottom blowing nitrogen with the strength of 0.03-0.06 Nm3The nitrogen is increased in the whole process.
In the smelting process, the lime consumption in the whole process is 25-29 kg/t steel, and the final slag binary alkalinity CaO/SiO2The value is 2.0 to 2.5.
In the smelting process, the oxygen lance with the 5+1 hole nozzle structure is provided with a central hole and five peripheral holes surrounding the central hole, the spray hole inclination angles of the five peripheral holes are 13 degrees, the Mach number is 2.02, and the theoretical penetration ratio is 72 percent.
In the smelting process, the oxygen lance with the 5-hole uniformly-distributed nozzle structure is provided with five uniformly-distributed peripheral holes, the spray hole inclination angles of the five peripheral holes are 13.5 degrees, the Mach number is 2.05, and the penetration ratio of the theoretical jet flow to a molten pool is 56%.
Under the condition that the ratio of the charged scrap steel is more than or equal to 30 percent, the invention promotes the rapid melting of the scrap steel in the initial smelting stage, and solves the adverse effect of the stacking phenomenon of the scrap steel (namely the stacking height of the scrap steel exceeds the liquid level of the steel) on smelting. In smelting, the slag retention operation and the low alkalinity (CaO/SiO)2The range is 2.0-2.5), and the ultralow process cost control is realized by low lime consumption (less than or equal to 26 kg/t). At the smelting end point, on one hand, the carbon content of the molten steel is controlled within a proper range, the oxidability of slag and the molten steel is reduced, the problem that the bubbling of low-alkalinity slag at the smelting end point with higher carbon content is serious and the tapping is influenced is solved by top-blowing nitrogen, and simultaneously, nitrogen is effectively added to the molten steel under the condition of lower oxidability of the molten steel, so that the nitrogen content of the molten steel before the tapping reaches 30-50 ppm, and the nitrogen content reaches 40-70 ppm after the argon station is finished, thereby providing a good basis for the strengthening effect after the subsequent microalloying.
Compared with the prior art, the invention has the following beneficial effects:
(1) the converter charging scrap steel ratio is improved, the stability of the smelting process is ensured, the iron raw material cost can be obviously reduced, and the carbon emission of the steelmaking process is reduced.
(2) The smelting end point carbon content of more than 0.06 percent, the oxidability of the molten steel is weak, the nitrogen increasing process is easy to carry out, and the alloy yield is high.
(3) Through the operation of top-blowing nitrogen at the smelting end point, the foaming of slag is effectively reduced, the tapping is facilitated, meanwhile, nitrogen is effectively added to molten steel, the strengthening effect of microalloying of Ti, V and the like is optimized, the alloy consumption is reduced, and the production cost is further reduced.
Drawings
FIG. 1 is a schematic view of a 5+1 hole lance structure used in the present invention;
FIG. 2 is a schematic view of a 5-hole lance with a uniformly distributed lance tip structure used in the present invention.
In the figure, 1-oxygen lance, 2-central hole and 3-peripheral hole.
Detailed Description
In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below with reference to specific examples, which are only exemplary to illustrate the technical solution of the present invention and do not limit the present invention in any way.
Example 1
The invention is explained in detail by taking a 140t top-bottom combined blown converter as an example to smelt HRB400E deformed steel, and the method specifically comprises the following steps:
(1) charging molten iron conditions
In the embodiment, the molten iron amount is 96t, the phosphorus content and the silicon content of the molten iron are 0.12 percent and 0.4 percent, the molten iron is desulfurized by adopting KR pretreatment, the sulfur content of the desulfurized molten iron is 30ppm, and the temperature of the molten iron before being added into the converter is 1300 ℃;
(2) heat balance
A slag remaining operation system is implemented, the smelting in the last furnace is completed, the tapping is finished, 40 percent of the total slag is left, and the furnace body is shaken to prepare the smelting in the next furnace; preheating scrap steel to 700 ℃ in advance, feeding molten iron into the furnace at 1300 ℃, adding 19.2 tons of scrap steel, wherein the silicon content of the molten iron is 0.4 percent, and the upper limit of the total amount of metal materials charged into the furnace is 115.2 tons;
(3) loading operation
After the last furnace is smelted, slag is left, slag is splashed to protect the furnace, the furnace body is inclined, firstly, scrap steel is filled into the furnace, then molten iron is added, then, the furnace body is inclined once in the opposite direction, then, the furnace body is shaken to ensure that the scrap steel is distributed in a molten pool basically and uniformly, the scrap steel is prevented from being accumulated on one side in the furnace, and at the moment, the scrap steel has a slight center accumulation phenomenon in the furnace;
(4) smelting process
After the converter body is rotated, referring to figure 1, an oxygen lance with a 5+1 hole nozzle structure is used for directly blowing, the initial lance position is controlled to be 3m, and the oxygen supply intensity is 3.2Nm3At/t.min, the higher lance position can prevent the contact damage of the oxygen lance nozzle and the high-piled non-molten waste steel on one hand, and can improve the secondary combustion rate of oxygen on the other hand, and CO in a furnace gas analysis system are analyzed2The proportion can be known, the secondary combustion rate can reach 20 percent, the rapid temperature rise in the furnace is facilitated, the lance position is gradually reduced after the blow-on is finished, the lance position is reduced to 2m when the blow-on is finished for 2min, the blow-on is stopped, the first batch of active lime 1.5t and the light-burned dolomite 0.8t are added, and 5 holes are immediately laid down from the top of the furnace to uniformly distribute the oxygen lances with the nozzle structure(see FIG. 2) the blowing was continued with a lance position of 1.8m and the oxygen supply intensity kept at 3.6Nm3Carrying out high-strength blowing at a time of 5min, transferring to a decarburization reaction stage when the total blowing time is 5min, quickly filling foamed slag in the furnace, adding 1.8t of second batch of active lime and 0.4t of light-burned dolomite, adjusting the gun position to a fixed value of 1.5m, and not adding other slagging materials such as the active lime, the dolomite and the like; controlling the smelting end point C of the converter according to the range of 0.08%, obtaining the total oxygen supply amount in the whole process through an empirical calculation formula, detecting the content of molten steel C by a TSO sublance probe and the temperature of the molten steel 1620 ℃ after the oxygen supply amount reaches a target value, rapidly changing the gas supply of an oxygen lance into nitrogen, adjusting the lance position to 2m, and adjusting the gas supply intensity to 2.4Nm3T.min, top-blowing nitrogen for 2min, tapping temperature 1612 ℃, molten steel P content of 0.018%, and molten steel S content of 0.011%, then normally tapping and alloying, and finishing the smelting process; and the molten steel has the liquid nitrogen content of 30ppm at the smelting end point, and the molten steel has the nitrogen content of 40ppm after alloying in tapping and bottom blowing argon to an argon station for uniformly mixing.
The smelting process also comprises the whole process of bottom blowing nitrogen with the strength of 0.05Nm3The nitrogen is increased in the whole process.
In the smelting process, the lime consumption in the whole process is 29kg/t steel, and the final slag binary alkalinity CaO/SiO2The value was 2.2.
Referring to fig. 1, in the smelting process, the 5+1 hole nozzle structure oxygen lance 1 is provided with a central hole 2 and five peripheral holes 3 surrounding the central hole, the spray hole inclination angle of the five peripheral holes is 13 degrees, the Mach number is 2.02, and the theoretical penetration ratio is 72%. The same applies below.
Referring to FIG. 2, in the above smelting process, the 5-hole uniformly-distributed lance 1 with a nozzle structure has five uniformly-distributed peripheral holes 3, the inclination angles of the spray holes of the five peripheral holes are 13.5 degrees, the Mach number is 2.05, and the penetration ratio of the theoretical jet flow to the molten pool is 56%. The same applies below.
Compared with the average 35kg/t steel for smelting the steel type, the total slag consumption of the embodiment is obviously less, the nitrogen content of the molten steel is high, the strengthening dosage of the subsequent V, Ti alloy is less, and the cost is lower.
Example 2
The invention is explained in detail by taking a top-bottom combined blown converter (140 t) as an example for smelting deformed steel bar HRB400E as a smelting production method of an extremely low-cost deformed steel bar converter, and the embodiment specifically comprises the following steps:
(1) charging molten iron conditions
In the embodiment, the molten iron amount is 105t, the phosphorus content and the silicon content of the molten iron are 0.15% and 0.6%, the molten iron is desulfurized by adopting KR pretreatment, the sulfur content of the desulfurized molten iron is 50ppm, and the temperature of the molten iron before being added into the converter is 1400 ℃;
(2) heat balance
A slag remaining operation system is implemented, the smelting in the last furnace is completed, the tapping is finished, 50 percent of the total slag is left, and the furnace body is shaken to prepare the smelting in the next furnace; preheating the scrap steel to 680 ℃ in advance, wherein the adding amount of the scrap steel is 40t, and the total amount of metal fed into the furnace is 145 t.
(3) Loading operation
After the last furnace is smelted, slag is left, slag is splashed and the furnace is protected, the furnace body is tilted, firstly, scrap steel is loaded into the furnace, then molten iron is added, then, the furnace body is tilted towards the opposite direction for one time, then, the furnace body is tilted, the distribution of the scrap steel in a molten pool is ensured to be basically uniform, the scrap steel is prevented from being accumulated on one side in the furnace, and at the moment, the scrap steel has a central accumulation phenomenon in the furnace;
(4) smelting process
After the converter body is shaken up, the oxygen lance with a 5+1 hole nozzle structure is used for directly blowing, the oxygen lance with the 5+1 hole nozzle structure is provided with a central hole and five peripheral holes surrounding the central hole, the total jet flow of the oxygen lance is more concentrated due to the existence of the central hole, the oxygen lance better acts on the middle part of the surface of a molten pool, the rapid melting of piled waste steel and the uniform mixing of the upper part and the lower part of the molten pool are obviously acted, the initial lance position is controlled to be 3.5m, and the oxygen supply intensity is 2.8Nm3At/t.min, the higher lance position can prevent the contact damage of the oxygen lance nozzle and the non-molten steel scrap at the stack height on one hand, and the high lance position can improve the secondary combustion rate of oxygen on the other hand, and CO in a furnace gas analysis system2The proportion can be known, the secondary combustion rate can reach 30 percent at the moment, the rapid temperature rise in the furnace is facilitated, the lance position is gradually reduced after the blow-on is finished, the lance position is reduced to 2.4m when the time is 2min, the blow-on is stopped, the first batch of active lime 1.8t and the light-burned dolomite 1t are added, and the oxygen lance with the structure of 5 holes and uniformly distributed nozzles is immediately put down from the top of the furnace, and the oxygen lance continues to blowSmelting with a lance position of 1.8m and oxygen supply intensity of 3.2Nm3T.min, performing high-strength blowing, when the total blowing time is 6min, transferring to a decarburization reaction stage, quickly filling foamed slag into the furnace, adding 2.1t of second batch of active lime and 0.6t of light-burned dolomite, adjusting the gun position to a fixed value of 1.5m, and adding 0.6t of iron ore for slag regulation 2 times when 15min is needed; controlling the smelting end point C of the converter according to the range of 0.10%, obtaining the total oxygen supply in the whole process through an empirical calculation formula, detecting that the content of the molten steel C is 0.098% and the temperature of the molten steel T =1625 ℃ through a TSO sublance probe after the oxygen supply reaches a target value, rapidly replacing the oxygen lance with nitrogen, adjusting the lance position to 2.4m, and adjusting the gas supply intensity to 2.8Nm3The steel tapping temperature is 1620 ℃, the content of P in the molten steel is 0.022%, the content of S is 0.009%, and then the steel tapping and alloying are normally carried out, and the smelting process is finished; and the molten steel has the liquid nitrogen content of 50ppm at the smelting end point, and the molten steel has the nitrogen content of 70ppm after alloying in tapping and bottom blowing argon to an argon station for uniformly mixing.
The smelting process also comprises the whole process of bottom blowing nitrogen with the strength of 0.06Nm3The nitrogen is increased in the whole process.
In the smelting process, the lime consumption in the whole process is 27kg/t steel, and the final slag binary alkalinity CaO/SiO2The value was 2.2.
Example 3
The invention is explained in detail by taking a 140t top-bottom combined blown converter as an example to smelt HRB500E deformed steel, and the method specifically comprises the following steps:
(1) conditions of molten iron
In the embodiment, the molten iron amount is 100t, the phosphorus content of the molten iron is less than or equal to 0.10 percent, the silicon content of the molten iron is 0.52 percent, the molten iron is desulfurized by adopting KR pretreatment, the sulfur content of the desulfurized molten iron is 25ppm, and the temperature of the molten iron before being added into the converter is 1370 ℃;
(2) heat balance
A slag remaining operation system is implemented, the smelting in the last furnace is completed, the tapping is finished, 40 percent of the total slag is left, and the furnace body is shaken to prepare the smelting in the next furnace; preheating the scrap steel to 600 ℃ in advance, adding 31t of the scrap steel, and adding 131t of the total metal in the furnace.
(3) Loading operation
After the last furnace is smelted, slag is left, slag is splashed to protect the furnace, the furnace body is inclined, firstly, scrap steel is filled into the furnace, then molten iron is added, then, the furnace body is inclined once in the opposite direction, then, the furnace body is swung to ensure that the scrap steel is distributed in a molten pool basically and uniformly, the scrap steel is prevented from being accumulated on one side in the furnace, and at the moment, the scrap steel has a central accumulation phenomenon in the furnace;
(4) smelting process
After the converter body is shaken up, the oxygen lance with a 5+1 hole nozzle structure is used for directly blowing, the oxygen lance with the 5+1 hole nozzle structure is provided with a central hole and five peripheral holes surrounding the central hole, the total jet flow of the oxygen lance is more concentrated due to the existence of the central hole, the oxygen lance better acts on the middle part of the surface of a molten pool, the rapid melting of piled waste steel and the uniform mixing of the upper part and the lower part of the molten pool are obviously acted, the initial lance position is controlled to be 3.2m, and the oxygen supply intensity is 3.0Nm3At/t.min, the higher lance position can prevent the contact damage of the oxygen lance nozzle and the non-molten steel scrap at the stack height on one hand, and the high lance position can improve the secondary combustion rate of oxygen on the other hand, and CO in a furnace gas analysis system2The proportion can be known, the secondary combustion rate can reach 24 percent, the furnace is favorable for quickly raising the temperature, the lance position is gradually reduced after blowing is started, when the time is 2min, the lance position is reduced to 2.2m, the blowing and the lance lifting are stopped, the first batch of active lime 1.55t and the light-burned dolomite 0.9t are added, the 5-hole oxygen lance with the uniformly distributed nozzle structure is immediately put down from the furnace top, the blowing is continued, the lance position is 1.8m, and the oxygen supply intensity is kept at 3.4Nm3T.min, performing high-strength blowing, when the total blowing time is 5.5min, transferring to a decarburization reaction stage, quickly filling foamed slag into the furnace, adding 1.85t of second batch of active lime and 0.5t of light-burned dolomite, adjusting the gun position to a fixed value of 1.5m, and adding 0.2t of iron ore for slag regulation 1 time when 12min is needed; controlling the smelting end point C of the converter according to 0.06 percent, obtaining the total oxygen supply in the whole process through an empirical calculation formula, detecting the content of the molten steel C by a TSO sublance probe to be 0.06 percent and the temperature of the molten steel T =1600 ℃ after the oxygen supply reaches a target value, rapidly replacing the oxygen lance with nitrogen, adjusting the lance position to be 2.2m, and adjusting the gas supply intensity to be 2.6Nm3T.min, realizing the rapid nitrogen increase of a molten pool, blowing the nitrogen gas from the top for 2.6min, tapping at the temperature of 1590 ℃, ensuring that the P content of the molten steel is 0.016 percent and the S content is 0.012 percent, and then normally dischargingAlloying steel and finishing the smelting process; and the nitrogen content of the molten steel at the smelting end point is 42ppm, and the nitrogen content of the molten steel reaches 55ppm after the molten steel is alloyed and argon is blown at the bottom of an argon station to be uniformly mixed.
The smelting process also comprises the whole process of bottom blowing nitrogen with the strength of 0.04Nm3The/t.min is beneficial to increasing nitrogen in the whole process.
In the smelting process, the lime consumption in the whole process is 26kg/t steel, and the final slag binary alkalinity CaO/SiO2The value was 2.3.
Example 4
The invention is explained in detail by taking a 140t top-bottom combined blown converter as an example to smelt HRB500E deformed steel, and the method specifically comprises the following steps:
(1) conditions of molten iron
In the embodiment, the molten iron amount is 102t, the phosphorus content and the silicon content of the molten iron are 0.11% and 0.58%, the molten iron is desulfurized by adopting KR pretreatment, the sulfur content of the desulfurized molten iron is 35ppm, and the temperature of the molten iron before being added into a converter is 1388 ℃;
(2) heat balance
A slag remaining operation system is implemented, the smelting in the last furnace is completed, the tapping is finished, 48 percent of the total slag is remained, and the furnace body is shaken to prepare the smelting in the next furnace; preheating the scrap steel to 690 ℃ in advance, adding the scrap steel with the amount of 37t, and adding the total amount of metal in the furnace with the amount of 139 t.
(3) Loading operation
After the last furnace is smelted, slag is left, slag is splashed and the furnace is protected, the furnace body is tilted, firstly, scrap steel is loaded into the furnace, then molten iron is added, then, the furnace body is tilted towards the opposite direction for one time, then, the furnace body is tilted, the distribution of the scrap steel in a molten pool is ensured to be basically uniform, the scrap steel is prevented from being accumulated on one side in the furnace, and at the moment, the scrap steel has a central accumulation phenomenon in the furnace;
(4) smelting process
After the converter body is shaken up, a 5+1 hole spray head structure oxygen lance is used for directly blowing, the 5+1 hole spray head structure oxygen lance is provided with a central hole and five peripheral holes surrounding the central hole, the total jet flow of the oxygen lance is more concentrated due to the existence of the central hole, the oxygen lance better acts on the middle part of the surface of a molten pool, and the oxygen lance quickly melts and melts piled waste steelThe mixing of the upper and lower parts of the pool has obvious effect, the initial gun position is controlled at 3.3m, and the oxygen supply intensity is 2.9Nm3At/t.min, the higher lance position can prevent the contact damage of the oxygen lance nozzle and the high-piled non-molten waste steel on one hand, and can improve the secondary combustion rate of oxygen on the other hand, and CO in a furnace gas analysis system are analyzed2The proportion can be known, the secondary combustion rate can reach 28 percent, the furnace is favorable for quickly raising the temperature, the lance position is gradually reduced after blowing is started, when the time is 2min, the lance position is reduced to 2.3m, the blowing and the lance lifting are stopped, the first batch of active lime 1.6t and the light burned dolomite 0.9t are added, the 5-hole oxygen lance with the uniformly distributed nozzle structure is immediately put down from the furnace top, the blowing is continued, the lance position is 1.8m, and the oxygen supply intensity is kept at 3.5Nm3Carrying out high-intensity blowing at a time of 5.3min, transferring to a decarburization reaction stage, quickly filling foamed slag in the furnace, adding 1.88t of second batch of active lime and 0.55t of light-burned dolomite, adjusting the gun position to a fixed value of 1.5m, and adding 0.3t of iron ore for slag adjustment at a time of 10min for 1 time; controlling a smelting end point C of the converter according to 0.075%, obtaining total oxygen supply amount in the whole process through an empirical calculation formula, detecting the content of the molten steel C by a TSO sublance probe to be 0.075% and the temperature of the molten steel T =1612 ℃ after the oxygen supply amount reaches a target value, rapidly replacing the oxygen lance gas supply with nitrogen, adjusting the lance position to 2.1m, and adjusting the gas supply intensity to be 2.5Nm3The method comprises the following steps of (1) enabling the nitrogen to be rapidly added in a molten pool at a time of 2.4min by top blowing nitrogen, controlling the tapping temperature to be 1606 ℃, controlling the P content of molten steel to be 0.017% and the S content to be 0.009%, then normally tapping and alloying, and finishing the smelting process; and the nitrogen content of molten steel at the smelting end point is 38ppm, and the nitrogen content of the molten steel reaches 50ppm after the molten steel is alloyed and argon is blown at the bottom of an argon station to be uniformly mixed.
The smelting process also comprises the whole process of bottom blowing nitrogen with the strength of 0.03Nm3The/t.min is beneficial to increasing nitrogen in the whole process.
In the smelting process, the lime consumption in the whole process is 25kg/t steel, and the binary alkalinity of the final slag is CaO/SiO2The value was 2.0.
Example 5
The invention is explained in detail by taking a 140t top-bottom combined blown converter as an example to smelt HRB500E deformed steel, and the method specifically comprises the following steps:
(1) conditions of molten iron
In the embodiment, the molten iron amount is 98t, the phosphorus content and the silicon content of the molten iron are 0.09 percent and 0.30 percent respectively, KR is adopted to pretreat the molten iron for desulfurization, the sulfur content of the desulfurized molten iron is 46ppm, and the temperature of the molten iron before being added into the converter is 1330 ℃.
(2) Heat balance
A slag remaining operation system is implemented, the smelting in the last furnace is completed, the tapping is finished, 42 percent of the total slag amount is remained, and the furnace body is shaken to prepare the smelting in the next furnace; preheating the scrap steel to 660 ℃ in advance, adding the scrap steel for 22t, and adding the total amount of metal in the furnace for 120 t.
(3) Loading operation
After the last furnace is smelted, slag is left, slag is splashed and the furnace is protected, the furnace body is tilted, firstly, scrap steel is loaded into the furnace, then molten iron is added, then, the furnace body is tilted towards the opposite direction for one time, then, the furnace body is tilted, the distribution of the scrap steel in a molten pool is ensured to be basically uniform, the scrap steel is prevented from being accumulated on one side in the furnace, and at the moment, the scrap steel has a central accumulation phenomenon in the furnace;
(4) smelting process
After the converter body is shaken up, the converter body directly starts blowing by using the oxygen lance with the 5+1 hole spray head structure, the oxygen lance with the 5+1 hole spray head structure is provided with a central hole and five peripheral holes surrounding the central hole, the jet flow of the oxygen lance is more concentrated due to the existence of the central hole, the oxygen lance better acts on the middle part of the surface of a molten pool, the oxygen lance has obvious effects on quick melting of piled waste steel and uniform mixing of the upper part and the lower part of the molten pool, the initial lance position is controlled to be 3.1m, and the oxygen supply intensity is 3.1Nm3At/t.min, the higher lance position can prevent the contact damage of the oxygen lance nozzle and the high-piled non-molten waste steel on one hand, and can improve the secondary combustion rate of oxygen on the other hand, and CO in a furnace gas analysis system are analyzed2The proportion can be known, the secondary combustion rate can reach 22 percent, the furnace is favorable for quickly raising the temperature, the lance position is gradually reduced after blowing is started, when the time is 2min, the lance position is reduced to 2.1m, the blowing and the lance lifting are stopped, the first batch of active lime 1.51t and the light burned dolomite 0.82t are added, 5 holes of the oxygen lance with the uniformly distributed nozzle structure are immediately put down from the furnace top, the blowing is continued, the lance position is 1.8m, the oxygen supply intensity is kept at 3.55Nm3At/t.min, performing high-intensity blowing, and transferring to a decarburization reaction stage when the total blowing time is 5.1minFirstly, quickly filling foamed slag into the furnace, adding 1.81t of second batch of active lime and 0.45t of light-burned dolomite, adjusting the gun position to a fixed value of 1.5m, and not adjusting slag in the process; controlling the smelting end point C of the converter according to 0.065%, obtaining total oxygen supply in the whole process through an empirical calculation formula, detecting the content of the molten steel C by a TSO sublance probe at 0.065% and the temperature of the molten steel T =1624 ℃ after the oxygen supply reaches a target value, rapidly replacing the oxygen lance with nitrogen, adjusting the lance position to 2.1m, and adjusting the gas supply intensity to 2.7Nm3The method comprises the following steps of (1) t.min, realizing rapid nitrogen increase of a molten pool, wherein the top-blown nitrogen time is 2.8min, the tapping temperature is 1618 ℃, the P content of molten steel is 0.015 percent, the S content is 0.010 percent, then, normally tapping and alloying are carried out, and the smelting process is finished; and the liquid nitrogen content of the steel at the smelting end point is 34ppm, and the nitrogen content of the molten steel reaches 46ppm after the steel is alloyed and argon gas is blown at the bottom of an argon station and is uniformly mixed.
The smelting process also comprises the whole process of bottom blowing nitrogen with the strength of 0.035Nm3The nitrogen is increased in the whole process.
In the smelting process, the lime consumption in the whole process is 27kg/t steel, and the binary alkalinity of the final slag is CaO/SiO2The value was 2.3.
Claims (5)
1. The method for smelting and producing the deformed steel bar with extremely low cost by a converter is characterized by comprising the following steps:
(1) raw material requirements
The molten iron amount is 96-105 t, the phosphorus content of the molten iron is less than or equal to 0.15%, the silicon content is 0.3-0.6%, the molten iron is desulfurized by adopting KR pretreatment, the sulfur content of the desulfurized molten iron is less than or equal to 50ppm, and the temperature of the molten iron before being added into a converter is more than or equal to 1300 ℃;
(2) heat balance
A slag remaining operation system is implemented, the smelting in the last furnace is completed, the tapping is finished, 40-50% of the total slag is left, the furnace body is shaken up, and the next furnace is prepared for smelting; preheating scrap steel to 600-700 ℃ in advance, taking the temperature of molten iron entering a furnace as 1300 ℃ and the silicon content of the molten iron as references, and adding the scrap steel with the reference amount of 96t, wherein on the basis, when the temperature of the molten iron rises by 10 ℃, the amount of the scrap steel is correspondingly increased by 1.2-1.5 t, when the silicon content of the molten iron rises by 0.1%, the amount of the scrap steel is correspondingly increased by 1.8-2 t, and the total amount of the scrap steel is limited to 105 t;
(3) loading operation
After the last furnace is smelted, slag is left, slag is splashed and the furnace is protected, the furnace body is tilted, firstly, scrap steel is loaded into the furnace, then molten iron is added, then, the furnace body is tilted towards the opposite direction for one time, then, the furnace body is tilted, the distribution of the scrap steel in a molten pool is ensured to be basically uniform, the scrap steel is prevented from being accumulated on one side in the furnace, and at the moment, the scrap steel has a central accumulation phenomenon in the furnace;
(4) smelting process
After the converter body is shaken up, directly blowing by using an oxygen lance with a 5+1 hole nozzle structure, controlling the initial lance position to be 3-3.5 m and the oxygen supply intensity to be 2.8-3.2 Nm3At the moment, the secondary combustion rate can reach 20-30%, the lance position gradually descends after blowing is started, when the lance position descends to 2-2.4 m after 2min, the lance is stopped blowing and lifting, 1.5-1.8 t of first active lime and 0.8-1 t of light burned dolomite are added, 5 holes are immediately put down from the top of the furnace, the lance with the uniformly distributed nozzle structure is blown continuously, the lance position is 1.8m, the oxygen supply intensity is kept at 3.2-3.6 Nm3Carrying out high-strength blowing at a time of 5-6 min, transferring to a decarburization reaction stage, quickly filling foamed slag in the furnace, adding 1.8-2.1 t of second batch of active lime and 0.4-0.6 t of light-burned dolomite, adjusting the gun position to a fixed value of 1.5m, adding 0.2-0.6 t of iron ore for slag regulation in 1-2 times within 7-15 min if the slag returns to be dry, and adding no active lime and dolomite slag-making materials if no abnormal phenomenon exists; controlling a smelting end point C of the converter according to the range of 0.06-0.10%, obtaining the total oxygen supply in the whole process through an empirical calculation formula, detecting the content of the molten steel C and the temperature T of the molten steel through a TSO sublance probe after the oxygen supply reaches a target value, wherein the content of the molten steel C and the temperature T of the molten steel are detected, the content of FeO is high due to low alkalinity of furnace slag, the total foaming of the furnace slag is still serious, the steel tapping is not facilitated at the moment, if the measured temperature of the molten steel is more than or equal to 1600 ℃, rapidly supplying gas to an oxygen lance and replacing the oxygen lance with nitrogen, adjusting the lance position to 2-2.4 m, and adjusting the gas supply intensity to 2.4-2.8 Nm3T.min, converting the foam slag layer into a liquid slag layer, blowing nitrogen gas from the top for 2-3 min, cooling to 5-10 ℃, controlling the tapping temperature to 1590-1620 ℃, controlling the molten steel P to be less than or equal to 0.022% and S to be less than or equal to 0.012%, and then normally tapping and alloying to finish the smelting process; the content of liquid nitrogen of the steel at the smelting end point is 30-50 ppm, and the steel is alloyed to the bottom of an argon stationAnd after argon is blown and mixed uniformly, the nitrogen content of the molten steel reaches 40-70 ppm.
2. The extremely low-cost deformed steel bar converter smelting production method of claim 1 is characterized in that: the process of claim 1, further comprising a total bottom-blowing of nitrogen gas at a strength of 0.03 to 0.06Nm3The/t.min is beneficial to increasing nitrogen in the whole process.
3. The extremely low-cost deformed steel bar converter smelting production method of claim 1 is characterized in that: the process of claim 1, wherein the total lime consumption is 22-26 kg/t steel, and the final slag has a binary basicity of CaO/SiO2The value is 2.0 to 2.5.
4. The extremely low-cost deformed steel bar converter smelting production method of claim 1 is characterized in that: the oxygen lance with the 5+1 hole nozzle structure is provided with a central hole and five peripheral holes surrounding the central hole, the spray hole inclination angles of the five peripheral holes are 13 degrees, the Mach number is 2.02, and the theoretical penetration ratio is 72 percent.
5. The extremely-low-cost converter smelting production method of deformed steel bar according to claim 1, characterized by comprising the following steps: the oxygen lance with the spray head structure with 5 holes uniformly distributed is provided with five uniformly distributed peripheral holes, the spray hole inclination angles of the five peripheral holes are 13.5 degrees, the Mach number is 2.05, and the penetration ratio of theoretical jet flow to a molten pool is 56 percent.
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| CN112375974A (en) * | 2020-10-28 | 2021-02-19 | 南京钢铁股份有限公司 | Deformed steel bar produced by high-chromium molten iron and preparation method thereof |
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| KR20120000792A (en) * | 2010-06-28 | 2012-01-04 | 현대제철 주식회사 | Oxygen lance for molten metal purifying processutilizing furnace and method for checking ignition |
| CN103614609A (en) * | 2013-12-04 | 2014-03-05 | 中冶东方工程技术有限公司 | Molten iron desilication method for stainless steel smelting |
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