CN114438276B - Method for shortening smelting period of converter - Google Patents
Method for shortening smelting period of converter Download PDFInfo
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- CN114438276B CN114438276B CN202210130550.XA CN202210130550A CN114438276B CN 114438276 B CN114438276 B CN 114438276B CN 202210130550 A CN202210130550 A CN 202210130550A CN 114438276 B CN114438276 B CN 114438276B
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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
- 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
- C21C5/36—Processes yielding slags of special composition
-
- 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
- C21C5/42—Constructional features of converters
- C21C5/44—Refractory linings
- C21C5/441—Equipment used for making or repairing linings
- C21C5/443—Hot fettling; Flame gunning
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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
- C21C5/42—Constructional features of converters
- C21C5/46—Details or accessories
- C21C5/4606—Lances or injectors
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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
- C21C5/42—Constructional features of converters
- C21C5/46—Details or accessories
- C21C5/4653—Tapholes; Opening or plugging thereof
-
- 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
- C21C5/42—Constructional features of converters
- C21C5/46—Details or accessories
- C21C5/4673—Measuring and sampling devices
-
- 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
- C21C7/0025—Adding carbon material
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Abstract
The application provides a method for shortening the smelting period of a converter, which comprises the steps of optimizing a charging process, optimizing an oxygen lance nozzle design, optimizing an oxygen supply and slagging system and optimizing a converter bottom blowing system, the long service life of a steel tapping hole is used, the slag splashing process is optimized, the compression auxiliary furnace reversing time is combined, the TCO bullet-throwing type sublance is controlled to be introduced and efficiently used, the purpose that a converter has 18 furnaces for stable production in a single shift and the production capacity of 19 furnaces is achieved, the smelting period of the single furnace is stably controlled within 25 +/-1 min, the one-time-reversal hit rate of the converter is not lower than 95%, the direct steel tapping proportion of the converter is not lower than 50%, the steel tapping hole reaches more than 450 furnaces with the long service life, the full flow control from the time when the gun is placed for blowing to the time when steel tapping is started is achieved within 14.5min, the perfect efficient slag adjusting and splashing process is formulated, the full-flow maximized fusion is achieved, the smelting period is shortened, and the effects of cost reduction and efficiency improvement are achieved.
Description
Technical Field
The invention relates to the technical field of converter steelmaking, in particular to a method for shortening a converter smelting period.
Background
In recent years, with the development of modern science and technology, steel enterprises are strongly promoting structure optimization, and steel-making production is developing towards realizing a compact continuous professional production line, realizing a high-efficiency fast-paced production process, further improving the cleanliness of molten steel, realizing production and management intellectualization, and reducing consumption and pollution. The converter smelting period is one of the comprehensive technical indexes for measuring the converter steelmaking level and is closely related to the converter steel yield, the operation process, the molten steel quality, the equipment operation rate and the like. At present, the level of the smelting period of an advanced steel enterprise converter reaches less than or equal to 25 min.
In a certain steel plant, the design production capacity of a continuous casting machine is greater than that of a converter, the conventional smelting period of the converter is 30-36 min at present, and the converter process becomes a bottleneck limiting link. Therefore, the smelting period of the converter is shortened, and the realization of high-efficiency production is an urgent problem to be solved; the efficient and fast-paced production is realized, the significance is not only that the technical and economic indexes of the converter are optimized, but also that the furnace machine matching of full continuous casting is realized, the casting blank direct rolling process is ensured, and the stable, balanced and smooth production of a steel-making system is ensured.
The converter smelting period comprises two parts of blowing time and auxiliary time (including iron adding, steel tapping, slag splashing, temperature measurement sampling, slag pouring and the like), the ratio of the blowing time of an advanced steel enterprise to the auxiliary time is basically about 1 (1-0.8), and the ratio of the converter blowing time of a part of steel enterprises to the auxiliary time is 1 (1.3-1.5), so that the space for compressing the blowing time and reducing the auxiliary time is huge, technical improvement is needed to release larger capacity, and higher efficiency and benefit are obtained.
Disclosure of Invention
The invention aims to provide a method for shortening the smelting period of a converter.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a method for shortening the smelting period of a converter is provided, and the oxygen supply system is improved:
1) the oxygen lance is in a blowing waiting position within 30s before the blowing begins, so that the lance descending time length is prevented from being increased from the high lance descending time;
2) adopting a dry method for dedusting, and adding granular steel for 1.5 t-2.5 t after the oxygen lance is normally ignited;
3) the total oxygen converting process adopts constant gun pressure changing operation, the oxygen pressure is 0.85MPa to 0.95MPa, and the basic gun position is 1.2m to 1.3 m;
4) the gun pressing time of more than or equal to 15s is ensured before the end point, and the end point C is controlled according to 0.07-0.09%.
Preferably, the oxygen lance adopts the oxygen flow rate which is 65 to 70 percent of the oxygen flow rate during normal blowing for ignition;
when the slagging trend is bad, a small-amplitude moving gun plus 0.2m and steel or dust removal ash are adopted for intervention;
when low-temperature slag overflow occurs, the early intervention is carried out by adopting a quick high-low gun position of 1.3 m-1.5 m;
1-1.5 min before the end point, according to the actual slagging, the operation of quickly lifting, slowly lowering, height lowering and slag adjusting is carried out, and after the gun is lifted to the fire, the gun is lowered in multiple frequency and small amplitude, so that the final slag condition and the dephosphorization effect are stabilized.
Preferably, the charging process is refined, decomposed and improved: the whole process of adding the scrap steel is controlled to be less than or equal to 30s, the preparation time of running and hooking of the two traveling cranes is controlled to be less than or equal to 45s, the whole process of adding the molten iron is controlled to be less than or equal to 105s, and the safe stopping distance between the molten iron tank and the scrap steel hopper from the fire door is not more than 1.5 m.
Preferably, the oxygen lance nozzle is improved: the diameter of the throat is 12mm, Ma is 2.03, the included angle is 13 degrees, the design pressure is 0.85MPa, and the oxygen supply intensity of the whole blowing process is ensured to be not lower than 4.1m 3 /min·t。
Preferably, the converter bottom blowing system is optimized: the early stage bottom blowing flow is adjusted to be 0.06m 3 Min.t is beneficial to early-stage slagging and rapid temperature rise of a molten pool;
blowing for 4-8 min, and entering a drying-back period, wherein the FeO content in the furnace is low, and the bottom blowing flow is adjusted to be 0.03m 3 The per min-t is beneficial to relieving the occurrence of the drying return phenomenon and improving the dephosphorization efficiency;
the bottom blowing flow is adjusted to be 0.06m at the later stage of converting 3 The/min-t is beneficial to the carbon-oxygen reaction to tend to be balanced;
the bottom blowing flow reaches the maximum 0.08m after the gun is lifted at the end point 3 Min.t is beneficial to reducing the oxygen in steel, controlling the thickness of a slag layer and the foaming degree, improving the metal yield and ensuring the furnace reversing effect.
Preferably, the service life of the steel tapping hole is guaranteed: the material of the steel tapping hole is improved to MT-10A, and meanwhile, the first brick is designed to be split;
the coordination control between C-Mn-O-FeO is realized by the operation scheme of protecting C and controlling P to extract Mn, and the chemical erosion degree and rate are reduced;
meanwhile, the steel tapping temperature range is stably controlled to be 1600-1660 ℃ under the guidance of a static heat balance model by combining with production organization modes of different iron losses.
Preferably, slag splashing process optimization: mixing slag by adopting light-burned magnesium balls and coke pieces;
when the end point C is more than 0.1%, the coke dices are not added, and the slag layer uniformity and the slag splashing effect are ensured according to the lower limit gun position plus the gun position high-low alternate operation of 0.5-2.5 m;
when C is more than 0.08% and less than or equal to 0.1%, slag splashing starts at a blowing basic lance position of 2.5m after coke is added, and the lance is gradually lowered to a lower limit lance position +0.5m after slag particles at a furnace mouth are reduced;
when the C is more than or equal to 0.05% and less than or equal to 0.08%, adding coke, then starting slag splashing at the gun position of 3.0m, gradually descending the gun to the blowing basic gun position of 2.5m after the red fire at the furnace mouth disappears, and gradually descending the gun after the slag particles at the furnace mouth are rare;
when the C is less than 0.05 percent, controlling the gun position to be 3.2-3.5 m after adding the coke pieces, preventing the slag from overflowing, gradually descending the gun to 2.5m after the flame at the furnace mouth disappears, and gradually descending the gun after observing that the slag particles at the furnace mouth are rare.
Preferably, the combined compression auxiliary furnace-reversing time length is as follows: the method adopts 1 furnace full slag remaining, furnace reversing temperature measurement sampling, 1 furnace direct reversing and slag reversing, and 2 furnace circulation to reduce the auxiliary furnace reversing time.
Preferably, with a TCO bullet-projecting sub-gun, the operating requirements are: slagging is good when the probe is detected, the gun pressing time before the probe is detected is more than 30s, feeding can not be carried out 3min before the probe is detected, and the temperature of molten steel is more than 1590 ℃ when the probe is detected;
when the oxygen lance is found to be seriously adhered with slag, the probe detection is carried out after the oxygen lance needs to be cleaned;
the furnace mouth must be cleaned when the slag is seriously adhered;
in the initial stage of use, the bullet can be shot after the oxygen lance is lifted to the oxygen closing point when the terminal lance is lifted for detection.
Compared with the prior art, the application obtains the following beneficial technical effects:
(1) the converter has the capability of stably producing 18 furnaces and finishing 19 furnaces on a single shift, and the smelting period of the single furnace is stably controlled within 25 +/-1 min, thereby reaching the domestic advanced level.
(2) The first-converter-pouring hit rate is not lower than 95%, and the direct converter tapping proportion is not lower than 50%.
(3) The end point C is improved by not less than 0.015 percent, the end point residual Mn content is improved by not less than 0.03 percent, the TFe of the final slag is reduced by not less than 1.5 percent, the tapping temperature is reduced by not less than 10 ℃ in the same ratio, and the steel feeding temperature in refining is reduced by not less than 5 ℃.
(4) Through the targeted improvement on the material, the structure and the operation process of the sliding plate slag-stopping steel-tapping hole, the steel-tapping hole achieves the use effect of a furnace with the service life of more than 450.
(5) And the optimization design of an oxygen lance nozzle is combined, the whole process system of oxygen supply, slag making and slag retention is optimized and promoted, and the introduction and the use of a TCO bullet-throwing type sublance control system are combined, so that a new mode of ' 1 furnace full slag retention + furnace temperature measurement sampling → 1 furnace direct pouring + slag pouring ' 2 furnace circulation reduction auxiliary furnace pouring time is ensured, and the whole flow control from the beginning of gun discharging preparation blowing to the beginning of tapping ' is ensured within 14.5 min.
(6) And a perfect high-efficiency slag-regulating and slag-splashing process is formulated, so that the full flow of slag retention, slag splashing, dry-method semi-oxygen ignition, converting process and converter reversing is maximally fused, the time is shortened, and the effects of cost reduction and efficiency improvement are achieved.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The application provides a method for shortening the smelting period of a converter, and an oxygen supply system is improved as follows:
1) the oxygen lance is in a blowing waiting position within 30s before the blowing begins, so that the lance descending time length is prevented from being increased from the high lance descending time;
2) adopting a dry method for dedusting, and adding granular steel for 1.5 t-2.5 t after the oxygen lance is normally ignited;
3) the total oxygen converting process adopts constant gun pressure changing operation, the oxygen pressure is 0.85MPa to 0.95MPa, and the basic gun position is 1.2m to 1.3 m;
4) the gun pressing time of more than or equal to 15s is ensured before the end point, and the end point C is controlled according to 0.07-0.09%.
In one embodiment of the application, the oxygen lance is ignited with an oxygen flow rate which is 65 to 70 percent of the oxygen flow rate during normal blowing;
when the slagging has bad tendency, a small-amplitude moving gun with the diameter of 0.2m and the addition of grain steel or dust removal ash are adopted for intervention;
when low-temperature slag overflow occurs, the early intervention is carried out by adopting a quick high-low gun position of 1.3 m-1.5 m;
1-1.5 min before the end point, according to the actual slagging, the operation of quickly lifting, slowly lowering, height lowering and slag adjusting is carried out, and after the gun is lifted to the fire, the gun is lowered in multiple frequency and small amplitude, so that the final slag condition and the dephosphorization effect are stabilized.
In one embodiment of the present application, the load flow is refined, decomposed, and improved: the whole process of adding the scrap steel is controlled to be less than or equal to 30s, the preparation time of running and hooking of the two traveling cranes is controlled to be less than or equal to 45s, the whole process of adding the molten iron is controlled to be less than or equal to 105s, and the safe stopping distance between the molten iron tank and the scrap steel hopper from the fire door is not more than 1.5 m.
In one embodiment of the present application, a lance tip is modified: the diameter of the throat is 12mm, Ma is 2.03, the included angle is 13 degrees, the design pressure is 0.85MPa, and the oxygen supply intensity of the whole blowing process is ensured to be not lower than 4.1m 3 /min·t。
In one embodiment of the present application, a rotorOptimizing the blowing degree of the furnace bottom: the early stage bottom blowing flow is adjusted to be 0.06m 3 Min.t is beneficial to early-stage slagging and rapid temperature rise of a molten pool;
blowing for 4-8 min, and entering a drying-back period, wherein the FeO content in the furnace is low, and the bottom blowing flow is adjusted to be 0.03m 3 The per min-t is beneficial to relieving the occurrence of the drying return phenomenon and improving the dephosphorization efficiency;
the bottom blowing flow is adjusted to be 0.06m at the later stage of converting 3 The/min-t is beneficial to the carbon-oxygen reaction to tend to be balanced;
the bottom blowing flow reaches the maximum 0.08m after the gun is lifted at the end point 3 The/min.t is beneficial to reducing the oxygen in steel, controlling the thickness of a slag layer and the foaming degree, improving the metal yield and ensuring the effect of converter down.
In one embodiment of the application, the long service life of the tap hole is guaranteed as follows: the material of the steel tapping hole is improved to MT-10A, and meanwhile, the first brick is designed to be split;
the coordination control between C-Mn-O-FeO is realized by the operation scheme of protecting C and controlling P to extract Mn, and the chemical erosion degree and rate are reduced;
meanwhile, the steel tapping temperature range is stably controlled to be 1600-1660 ℃ under the guidance of a static heat balance model by combining with production organization modes of different iron losses.
In one embodiment of the present application, the slag splashing process is optimized: mixing slag by adopting a light-burned magnesium ball and a nut coke;
when the end point C is more than 0.1%, the coke dices are not added, and the slag layer uniformity and the slag splashing effect are ensured according to the lower limit gun position plus the gun position high-low alternate operation of 0.5-2.5 m;
when C is more than 0.08% and less than or equal to 0.1%, slag splashing starts at a blowing basic lance position of 2.5m after coke is added, and the lance is gradually lowered to a lower limit lance position +0.5m after slag particles at a furnace mouth are reduced;
when the C is more than or equal to 0.05% and less than or equal to 0.08%, adding coke, then starting slag splashing at the position of a gun of 3.0m, gradually descending the gun to the position of a blowing basic gun of 2.5m after red fire at a furnace mouth disappears, and gradually descending the gun after slag particles at the furnace mouth are rare;
when the C is less than 0.05 percent, controlling the gun position to be 3.2-3.5 m after adding the coke pieces, preventing the slag from overflowing, gradually descending the gun to 2.5m after the flame at the furnace mouth disappears, and gradually descending the gun after observing that the slag particles at the furnace mouth are rare.
In one embodiment of the present application, the compression assisted turndown duration is combined: the method adopts 1 furnace full slag remaining, furnace reversing temperature measurement sampling, 1 furnace direct reversing and slag reversing, and 2 furnace circulation to reduce the auxiliary furnace reversing time.
In one embodiment of the present application, using a TCO projectile type sublance, the operating requirements are: slagging is good when the probe is detected, the gun pressing time before the probe is detected is more than 30s, feeding can not be carried out 3min before the probe is detected, and the temperature of molten steel is more than 1590 ℃ when the probe is detected;
when the oxygen lance is found to be seriously adhered with slag, the probe detection is carried out after the oxygen lance needs to be cleaned;
the furnace mouth must be cleaned when the slag is seriously adhered;
in the initial stage of use, the bullet can be shot after the oxygen lance is lifted to the oxygen closing point when the terminal lance is lifted for detection.
The general principle of the technical scheme of the application is as follows:
1) the loading time of the steel scrap bucket and the molten iron tank is stably controlled within 3min, the waiting positions between the steel scrap bucket and the furnace mouth under the safety limit are measured and calculated, the waiting limit of the travelling crane is perfected, the accurate positioning is achieved, and the running time of the travelling crane is reduced;
the cooperation of the ground and the travelling crane is perfected, the running interval duration of the travelling crane is reduced, the furnace mouth cleaning and scrap steel distribution groove management regulation and operation are perfected, and scrap steel blocking, iron spraying and the like are required to be avoided.
2) The time of the whole blowing process is stably controlled within 13.5min, reasonable oxygen lance nozzle parameters are selected, correct oxygen supply parameters, a slagging system and bottom blowing sectional control are formulated, and the oxygen supply intensity is up to 3.7m 3 The lift of/min-t is not less than 4.1m 3 The melting process is adjustable and controllable in the/min.t, the utilization rate of oxygen and slag forming materials is stable, the melting process is guaranteed to be inverted, and the phenomena of dry returning, slag overflow, splashing, abnormal end point index, difficult furnace inversion and the like caused by abnormal melting are avoided.
3) The total tapping flow time is controlled within 4min, the material and design change of the tapping hole achieves the total high-temperature corrosion resistance and high-temperature compressive strength, the oxidation resistance is higher, the replacement rate is improved, the operation optimization and improvement effectively shield the influence of high-temperature melting loss and chemical erosion on the service life of the tapping hole, the service effect of the service life of the tapping hole above 400 furnaces is finally achieved, and the long service life of the tapping hole in the middle and later periods is ensured.
4) The time of the whole slag splashing flow is controlled within 3min, the saturation degree of MgO of the final slag is ensured by adopting slag splashing gun position optimization and adding magnesium balls, the FeO of the final slag is reduced by adding coke particles, the slag splashing purpose of 'splashing, sticking and erosion resistance' with rapidness, high efficiency and high quality is ensured, the influence of slag remaining operation on the slag splashing time can be shielded, and the subsequent operation effect and safety of the total remaining slag can be ensured.
5) The time of the whole process of furnace reversing, temperature measurement sampling and slag reversing is controlled within 1min, the optimization and improvement of a converting process and a slag splashing process are combined, two items are fused and coordinated with the system, 1 furnace full slag retention and furnace reversing temperature measurement sampling +1 furnace direct furnace reversing steel tapping and slag reversing are adopted, 2 furnace periodic cycle mode is adopted, and the comprehensive coordination control and guarantee of the total slag amount in the furnace, slag splashing furnace protection pressure, converting stability, dry semi-oxygen ignition smooth running and the like are achieved by verifying the end point and ensuring.
6) The TCO bullet-throwing type sublance control system is introduced and used to achieve the accurate measurement of the end point temperature and C and the judgment indication of P, thereby greatly improving the hit rate of the end point and the quality guarantee, and the direct converter-reversing proportion of the converter can be improved to more than 80%.
The technical scheme of the application has detailed implementation:
1.1) refining, decomposing and improving the loading process: the basic time schedule is 30s for the whole process of adding scrap steel, 45s for the running of two traveling cranes, hook preparation and the like, 105s for the whole process of adding molten iron, the safe stopping distance between a molten iron tank and a scrap steel hopper and a fire door is not more than 1.5m, and limit marks of waiting positions and loading positions are added to ensure the accurate positioning of the traveling cranes; in the process of withdrawing the bucket after adding the steel scraps, the hoisting tank travelling crane is timely connected to start, the steel scrap travelling crane is driven north, and the heavy tank travelling crane is timely followed; in the processes of commanding scrap steel adding and molten iron adding, the command is clear and accurate, and the matching of the running adding and the converter rocking is ensured.
1.2) design optimization of oxygen lance nozzle: under certain operating oxygen pressure and gun position conditions, the required oxygen supply intensity is provided for converting, so that the oxygen jet obtains larger kinetic energy and oxygenThe attenuation of jet flow along the axis is slowed down as much as possible, no negative pressure region and over-strong turbulent motion occur, so as to achieve proper penetration depth, uniformly stir the molten pool, erode the furnace lining little and uniformly, simultaneously, obvious re-drying, slag overflow, splashing and the like are not caused, the oxygen lance nozzle is optimally designed again, the parameters are that the diameter of the throat is 12mm, Ma is 2.03, the included angle is 13 degrees, the design pressure is 0.85MPa, and the oxygen supply intensity of the whole blowing process is ensured to be not less than 4.1m 3 /min·t。
1.3) oxygen supply and slagging system optimization and improvement:
1.3.1) the oxygen lance is in a blowing waiting position 30s before blowing, so that the time of lowering the lance from a high position is avoided;
1.3.2) adopting dry dedusting and starting to add about 2t of granular steel after the semi-oxygen low-flow ignition is normal (about 30 s), increasing the holding time of a low-temperature region in the early stage, increasing the FeO content in slag, generally improving and ensuring the early-stage dephosphorization effect, and reducing the subsequent dephosphorization pressure;
1.3.3) the total oxygen converting process basically adopts constant gun pressure changing operation (oxygen pressure is 0.85 MPa-0.95 MPa, and the basic gun position is 1.2-1.3 m), improves the oxygen utilization rate and stabilizes the slagging effect in the process, intervenes by slightly moving a gun (+0.2m) and adding a small amount of granular steel or dust if slagging tends to be bad, intervenes in advance by adopting a quick high and low gun position (1.3-1.5 m) if low-temperature slag overflow occurs, avoids the possibility that the slag overflows stick a furnace mouth for a long time, temperature loss and subsequent drying easily increases, strictly forbids slag regulation at the high gun position (more than 1.8m) for a long time (more than 45 s) after 8-9 min, and avoids the phenomena of splashing and slag overflow due to temperature stratification difference;
1.3.4) performing slag regulation operation (multiple frequency small-amplitude gun descending after rapid ascending and slow descending of a lifting gun to fire contracting) 1-1.5 min before the end point according to actual slag melting, and stabilizing the final slag condition and the dephosphorization effect;
1.3.5) ensuring the gun pressing time of more than or equal to 15s before the end point, ensuring proper fluidity and component temperature uniformity of the final slag condition, controlling the end point C according to about 0.07-0.09%, properly ensuring the FeO of the final slag, and avoiding the phenomenon that the slag surface is too high due to the blockage of gas removal caused by over-high viscosity of the slag;
1.3.6), ensuring the nitrogen slagging effect before furnace reversing, ensuring that nitrogen penetrates a slag layer at a gun position of 2.5-6 m, and then according to a furnace mouth and a nitrogen seal, flying slag actually flies out, wherein slag particles are dark red, fine and dense, so that the final slag viscosity, the foam degree and the like are determined, the furnace is reversed after nitrogen is blown at an oxygen point without conditions, and the condition of furnace reversing is avoided;
1.3.7) the furnace length participates in the smelting process after 6min, the P content is comprehensively judged by combining process control and sampling rod slag sample appearance, the P content is judged according to the actual process slagging and slag charge addition actual judgment end point, the P content is jointly evaluated by the furnace length, and the hit rate of unequal sample tapping and the accurate control of the straight pouring end point are ensured;
1.3.8) blowing for about 10min to confirm the slag pot and stop 'furnace waiting pot';
1.3.9) cleaning the slag channel in time in the low-flow converting process of 90s before half oxygen.
1.4) design optimization of a converter bottom blowing system: the early-stage bottom blowing flow is properly adjusted to be 0.06m 3 Min.t is beneficial to early-stage slagging and rapid temperature rise of a molten pool;
blowing for 4-8 min, returning to drying stage, reducing FeO content in the furnace, and properly reducing bottom blowing flow to 0.03m 3 Min. t is beneficial to relieving the occurrence of the phenomenon of drying back and improving the dephosphorization efficiency;
the bottom blowing flow is adjusted to be 0.06m at the later stage of converting 3 The/min-t is beneficial to the carbon-oxygen reaction to tend to be balanced;
the bottom blowing flow reaches the maximum 0.08m after the gun is lifted at the end point 3 The/min.t is beneficial to reducing the oxygen in steel, controlling the thickness of a slag layer and the foaming degree, improving the metal yield and ensuring the effect of converter down.
1.5) long service life guarantee of the steel tapping hole: according to actual smelting conditions, the total material quality of the steel tapping hole is improved from MT-12A to MT-10A, the total high-temperature corrosion resistance and high-temperature compressive strength of the steel tapping hole are improved, the oxidation resistance is higher, meanwhile, the first brick is designed to be split, the quick replacement is ensured, and a prerequisite condition is created for prolonging the service life of the steel tapping hole; the operation is improved: aiming at high-temperature melting loss and chemical erosion, the coordination control between C-Mn-O-FeO is continuously promoted and the chemical erosion degree and rate are reduced by continuously improving and implementing the process operation scheme of 'protecting C and controlling P to extract Mn'; meanwhile, by combining production organization modes with different iron losses, under the guidance of a static thermal balance model, the tapping temperature range is stably controlled to be 1600-1660 ℃, and the corresponding relation between 'R-MgO-T' is reasonably matched according to the tapping temperature, so that the MgO saturation in slag is optimally ensured, and the middle and later period running time of the tap hole is greatly prolonged.
1.6) implementation of a high-efficiency high-quality slag splashing process: the soft-burned magnesium balls are matched with the coke dices to carry out slag mixing together and follow up with the slag splashing gun position pertinence, particularly after the coke dices are adopted for slag mixing operation, the slag remaining condition, the slag splashing speed and the slag splashing effect are greatly improved, but when the coke dices are adopted for slag mixing at the end point C of less than 0.07 percent, severe carbon-oxygen reaction often occurs, and if the gun position is improperly controlled at the time, the slag overflowing accident is easily caused, so the slag splashing process operation is optimized and improved again;
when the end point C is more than 0.1%, alternately operating according to the normal gun position (lower limit gun position + 0.5-2.5 m) of high-low without adding coke pieces to ensure the uniformity of a slag layer and the slag splashing effect;
when C is more than 0.08% and less than or equal to 0.1%, slag splashing starts at a blowing basic lance position of 2.5m after coke is added, and the lance is gradually lowered after slag particles at a furnace mouth are reduced (the lower limit lance position is the lower limit lance position plus 0.5 m);
when the C is more than or equal to 0.05% and less than or equal to 0.08%, slag splashing starts when the amount of added coke is 3.0m higher than the blowing basic lance position, the lance is gradually lowered to the blowing basic lance position (2.5m) after the red fire at the furnace mouth disappears, and the lance is gradually lowered after the slag particles at the furnace mouth are rare;
when the C is less than 0.05 percent, controlling the gun position to be about 3.2-3.5 m after adding the coke, preventing the slag from overflowing, gradually descending the gun to 2.5m after the flame at the furnace mouth disappears, and gradually descending the gun after observing that the slag particles at the furnace mouth are rare.
1.7) merging the compression auxiliary furnace-reversing time: the novel mode of '1 furnace full slag remaining + converter temperature measurement sampling → 1 furnace direct converter and converter' 2 furnace circulation reduction auxiliary converter time is adopted, so that the comprehensive coordination and guarantee of terminal verification and guarantee of reasonable total slag amount in the furnace, reduction of slag splashing furnace protection pressure, promotion of converting stability, safe dry dedusting operation, smooth and efficient semi-oxygen ignition, weakening of continuous converter slag and the like are achieved.
1.8) TCO bullet-throwing type sublance control introduction and efficient use: TCO bullet-throwing type sublance control system has increased P prejudgement function on the original basic functions of temperature measurement, oxygen determination and carbon calculation of TCO, and TCO has the advantages of simple technical equipment, low investment cost, small occupied area, integrated assembly, convenient maintenance, reliable operation, quick detection and high precision, is close to a converter mechanical sublance in function, and sets TCO use rules for ensuring TCO high-efficiency measurement yield and accurate hit rate: firstly, a detection probe is hammered into the set depth of molten steel by gravity and speed, so that part of relevant factors can influence the representativeness of detection data in the smelting process; the operation requirements are as follows: the method is characterized in that the slag melting is good during probe detection, the gun pressing time before probe detection is more than 30s, feeding can not be carried out 3min before probe detection, the temperature during probe detection is more than 1590 ℃, the probability of the oxygen lance striking the oxygen lance in the falling process of the probe is increased due to serious slag/steel sticking of the oxygen lance, so that the detection failure probability of the probe is increased (when the oxygen lance is seriously stuck, the probe detection is carried out after the oxygen lance is cleaned), the furnace mouth must be cleaned immediately when the slag sticking is serious, and the bomb throwing operation can be carried out above the oxygen lance lifting point when the initial end point lance lifting detection is used (so as to avoid the influence of air flow on the track of the probe).
In the application, the unit of the element content and the component content is mass percent.
Methods and devices not described in detail in the present invention are all the prior art and are not described in detail.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (1)
1. A method for shortening the smelting period of a converter is characterized in that the oxygen supply system is improved:
1) the oxygen lance is in a blowing waiting position within 30s before the blowing begins, so that the lance descending time length is prevented from being increased from the high lance descending time;
2) adopting a dry method for dedusting, and adding granular steel for 1.5 t-2.5 t after the oxygen lance is normally ignited;
3) the total oxygen converting process adopts constant gun pressure changing operation, the oxygen pressure is 0.85MPa to 0.95MPa, and the basic gun position is 1.2m to 1.3 m;
4) the gun pressing time of more than or equal to 15s is ensured before the end point, and the end point C is controlled according to 0.07-0.09%;
the oxygen lance adopts the oxygen flow which is 65 to 70 percent of the oxygen flow during normal blowing to carry out ignition;
when the slagging has bad tendency, a small-amplitude moving gun with the diameter of 0.2m and the addition of grain steel or dust removal ash are adopted for intervention;
when low-temperature slag overflow occurs, the early intervention is carried out by adopting a quick high-low gun position of 1.3 m-1.5 m;
1-1.5 min before the end point, according to the actual slagging, performing quick-lifting, slow-lowering, high-low gun position slag regulation operation, lifting the gun to a low level, lowering the gun in multiple frequencies and small amplitude after the fire is closed, and stabilizing the final slag condition and the dephosphorization effect;
refining, decomposing and improving the loading process: the whole process of adding the scrap steel is controlled to be less than or equal to 30s, the preparation time of running and hooking of the two travelling cranes is controlled to be less than or equal to 45s, the whole process of adding the molten iron is controlled to be less than or equal to 105s, and the safe stopping distance between the molten iron tank and the scrap steel hopper from the fire door is not more than 1.5 m;
the improvement of the oxygen lance nozzle: the diameter of the throat is 12mm, Ma =2.03, the included angle is 13 degrees, the design pressure is 0.85MPa, and the oxygen supply intensity of the whole blowing process is ensured to be not lower than 4.1m 3 /min·t；
Optimizing a converter bottom blowing system: the early stage bottom blowing flow is adjusted to be 0.06m 3 Min.t is beneficial to early-stage slagging and rapid temperature rise of a molten pool;
blowing for 4-8 min, and entering a drying-back period, wherein the FeO content in the furnace is low, and the bottom blowing flow is adjusted to be 0.03m 3 The per min-t is beneficial to relieving the occurrence of the drying return phenomenon and improving the dephosphorization efficiency;
the bottom blowing flow is adjusted to be 0.06m at the later stage of converting 3 The/min-t is beneficial to the carbon-oxygen reaction to tend to be balanced;
the bottom blowing flow reaches the maximum 0.08m after the gun is lifted at the end point 3 The/min.t is beneficial to reducing oxygen in steel, controlling the thickness of a slag layer and the foaming degree, improving the metal yield and ensuring the effect of converter down;
the service life of the steel tapping hole is ensured: the material of the steel tapping hole is improved to MT-10A, and meanwhile, the first brick is designed to be split;
the coordination control between C-Mn-O-FeO is realized by the operation scheme of protecting C and controlling P to extract Mn, and the chemical erosion degree and rate are reduced;
meanwhile, combining production organization modes of different iron losses, and under the guidance of a static heat balance model, stably controlling the tapping temperature range to be 1600-1660 ℃;
optimizing a slag splashing process: mixing slag by adopting light-burned magnesium balls and coke pieces;
when the end point C is more than 0.1%, coke cubes are not added, and the slag layer uniformity and the slag splashing effect are ensured according to the gun position high-low alternative operation of the lower limit gun position + 0.5-2.5 m;
when C is more than 0.08% and less than or equal to 0.1%, slag splashing starts at a blowing basic lance position of 2.5m after coke is added, and the lance is gradually lowered to a lower limit lance position of +0.5m after slag particles at a furnace mouth are reduced;
when the C is more than or equal to 0.05% and less than or equal to 0.08%, adding coke, then starting slag splashing at the gun position of 3.0m, gradually descending the gun to the blowing basic gun position of 2.5m after the red fire at the furnace mouth disappears, and gradually descending the gun after the slag particles at the furnace mouth are rare;
when C is less than 0.05%, controlling the gun position to be 3.2-3.5 m after adding the coke pieces to prevent the slag from overflowing, gradually descending the gun to 2.5m after the flame at the furnace mouth disappears, and gradually descending the gun after observing that the slag particles at the furnace mouth are rare;
merging and compressing auxiliary furnace turnover time: 1, furnace full slag retention, furnace reversing temperature measurement sampling, 1 furnace direct reversing and slag reversing, and 2 furnace circulation are adopted to reduce the auxiliary furnace reversing time;
using a TCO projectile sublance, the operating requirements are: slagging is good when the probe is detected, the gun pressing time before the probe is detected is more than 30s, feeding can not be carried out 3min before the probe is detected, and the temperature of molten steel is more than 1590 ℃ when the probe is detected;
when the oxygen lance is found to be seriously adhered with slag, the probe detection is carried out after the oxygen lance needs to be cleaned;
the furnace mouth must be cleaned when the slag is seriously adhered;
in the initial stage of use, when the terminal lance is lifted and detected, the ammunition throwing operation is executed after the oxygen lance is lifted to an oxygen closing point or above.
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