CN112442566A - Converter bottom protection method - Google Patents
Converter bottom protection method Download PDFInfo
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- CN112442566A CN112442566A CN202011111943.3A CN202011111943A CN112442566A CN 112442566 A CN112442566 A CN 112442566A CN 202011111943 A CN202011111943 A CN 202011111943A CN 112442566 A CN112442566 A CN 112442566A
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- converter
- slag
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- high magnesium
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- 238000000034 method Methods 0.000 title claims abstract description 50
- 239000002893 slag Substances 0.000 claims abstract description 174
- 229910000514 dolomite Inorganic materials 0.000 claims abstract description 70
- 239000010459 dolomite Substances 0.000 claims abstract description 70
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000001301 oxygen Substances 0.000 claims abstract description 68
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 68
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 63
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 63
- 239000011777 magnesium Substances 0.000 claims abstract description 63
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 56
- 239000010959 steel Substances 0.000 claims abstract description 45
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 44
- 238000010079 rubber tapping Methods 0.000 claims abstract description 34
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 28
- 239000000571 coke Substances 0.000 claims abstract description 16
- 238000007664 blowing Methods 0.000 claims abstract description 14
- 230000009191 jumping Effects 0.000 claims abstract description 14
- 239000002245 particle Substances 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 9
- 238000002844 melting Methods 0.000 abstract description 8
- 239000011449 brick Substances 0.000 abstract description 7
- 238000012423 maintenance Methods 0.000 abstract description 6
- 238000009851 ferrous metallurgy Methods 0.000 abstract description 2
- 230000008018 melting Effects 0.000 abstract description 2
- 238000002791 soaking Methods 0.000 abstract description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 12
- 239000012535 impurity Substances 0.000 description 12
- 239000000395 magnesium oxide Substances 0.000 description 9
- 229910052742 iron Inorganic materials 0.000 description 8
- 238000009628 steelmaking Methods 0.000 description 7
- 239000002689 soil Substances 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 3
- 229910000851 Alloy steel Inorganic materials 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 239000011819 refractory material Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001021 Ferroalloy Inorganic materials 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- C21C5/48—Bottoms or tuyéres of converters
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention relates to the technical field of ferrous metallurgy processes, in particular to a converter bottom protection method, which comprises the following steps: s1, after converter tapping, the amount of slag left in the converter is 50-65 kg/tSteel(ii) a S2, adding medium-high magnesium dolomite into the converter, and then carrying out rocking at 30 degrees in front and at back, wherein the amount of the added medium-high magnesium dolomite is 1/2-5/6 of the total amount of the added medium-high magnesium dolomite in the step; s3, blowing nitrogen through an oxygen lance to perform slag splashing protection, adding coke to perform deoxidation operation when slag splashing occurs for 60s, adding 1/6-1/2 of the total addition of medium and high magnesium dolomite when the slag jumping out from a furnace mouth is rare, and then splashing for 30 s. The method of the invention can reduce the soaking and melting loss of high-temperature molten steel to the lining brick of the furnace, thereby protecting the lining brick of the furnace bottom, prolonging the service time of the converter and reducing the maintenance cost of the converter.
Description
Technical Field
The invention relates to the technical field of ferrous metallurgy processes, in particular to a converter bottom protection method.
Technical Field
Along with the higher and higher requirements of modern production life on the performance and quality of steel products, the application range of the steel products is wider and wider, and meanwhile, iron and steel production enterprises pay more and more attention to the improvement of the yield and quality of products, the expansion of varieties, the energy conservation and the reduction of cost. In this case, the converter production process is subject to great changes. The development of molten iron pretreatment, combined blown converter, external refining and continuous casting technology breaks through the traditional converter steelmaking mode. The process flow is a new process flow of molten iron pretreatment, combined blown converter blowing, external refining and continuous casting. The process is characterized by large-scale equipment, modernization and continuity. The oxygen converter is changed into a link of a new process from the original dominant position, and mainly takes the tasks of molten steel decarburization and temperature rise.
Converter steelmaking (converter steelmaking) is to use molten iron, scrap steel and ferroalloy as main raw materials, and the steelmaking process is completed in a converter by means of heat generated by physical heat of molten iron and chemical reaction among molten iron components without external energy. The converter is divided into acid and alkaline according to refractory materials, and top blowing, bottom blowing and side blowing are carried out according to the positions of gas blown into the converter; according to the gas types, the converter comprises an air separation converter and an oxygen converter. The basic oxygen top-blown converter and the top-bottom combined blown converter are the most common steelmaking equipment used at present due to high production speed, high yield, high single-furnace yield, low cost and low investment. The converter is mainly used for producing carbon steel, alloy steel and smelting copper and nickel.
Maintenance of the body of a converter is a long and important task in steel production. The converter bottom is an important component of the converter body and is always in a high-temperature and load-bearing state in the converter smelting process. Particularly, when low-carbon steel is continuously smelted, the liquid level of a converter molten pool is easy to drop, so that the converter bottom is seriously corroded, and a larger risk of converter penetration and leakage exists.
In order to solve the problems, in the prior art, furnace bottom maintenance is mostly carried out by adopting a method of repairing a furnace bottom by using a repairing material, and methods of filling magnesia carbon refractory bricks, condensing pig iron blocks and furnace slag, sintering fillers, blowing nitrogen to make slag on the surface of a furnace lining and the like are also adopted. However, the above method has the defects of more times of furnace bottom maintenance, long time, high refractory material cost, low converter operation rate and the like.
Disclosure of Invention
The invention aims to overcome the technical problems of more maintenance times, long time and the like of a converter in the prior art and provides a converter bottom protection method of the converter.
The purpose of the invention is realized by the following technical scheme:
a method for protecting the bottom of a converter comprises the following steps:
s1, after converter tapping, the amount of slag left in the converter is 50-65 kg/tSteel；
S2, adding medium-high magnesium dolomite into the converter, and then carrying out rocking at 25-35 degrees in front and at back, wherein the amount of the added medium-high magnesium dolomite is 1/2-5/6 of the total amount of the added medium-high magnesium dolomite in the step;
s3, blowing nitrogen through an oxygen lance to perform slag splashing protection, adding coke to perform deoxidation operation when slag splashing lasts for 55-70 s, adding 1/6-1/2 of the total addition of medium and high magnesium dolomite when slag jumping out of a furnace mouth is rare, and then splashing slag for 20-40 s;
wherein when the temperature of converter tapping is 1630-1650 ℃, the oxygen content at the end point is more than 400ppm, the slag amount after tapping is 7.6-8.5 t, and the total addition amount of medium-high magnesium dolomite is 8-9 kg/tSteel(ii) a The total adding amount of the coke is 3-4 kg/tSteel；
When the tapping temperature of the converter is 1650-1680 ℃, and the oxygen content at the end point is more than 600ppm, the slag remaining amount after tapping is 5.4-7 tSteelWhen the total adding amount of the medium-high magnesium dolomite is 8.5kg to 12.5kg/tSteel(ii) a The coke addition was 4.2kg/tSteel；
When the temperature of the converter tapping is more than 1680 ℃, the oxygen content at the end point is more than 800ppm, and the slag amount after tapping is 5.2-7 t, the addition amount of the medium-high magnesium dolomite is 12.5-16.6 kg/tSteel(ii) a The adding amount of the coke is 4.8-6 kg/tSteel。
The furnace protection method is carried out under the condition that the corrosion of the bottom bricks of the converter is detected to exceed 250 mm. The medium-high magnesium dolomite used in the method is conveyed to a converter auxiliary raw material high-level bin by an underground bin through a belt in advance, and the dolomite dosage required by furnace protection is weighed into a weighing hopper for later use by the high-level bin before each use.
After tapping is finished in the step S1, the furnace is rocked to the zero position, namely the charging angle of the converter. In the step S2, the furnace shaking operation is to shake the furnace at 30 degrees before and after the converter, so as to reduce the temperature of the slag in the furnace and promote part of the medium and high magnesium dolomite to sink to the bottom of the furnace. In the method, medium-high magnesium dolomite is added twice, and 1/2-5/6 of the total amount of the medium-high magnesium dolomite is added before the slag splashing of the converter begins; and when the slag splashing is carried out for 55-70 s, the slag in the converter is preliminarily cooled, the viscosity of the slag is enhanced, and coke is added from a converter bin to carry out deoxidation treatment on the slag. When the slag concentration at the furnace mouth is reduced, 1/6-1/2 of the total amount of the rest medium-high magnesium dolomite is added 20-40 seconds before slag splashing is finished to carry out furnace bottom padding operation. The adding method can further ensure the effects of splashing slag and furnace bottom padding of the furnace slag, so that the furnace slag is rapidly cooled and firmly adhered to the furnace bottom lining, and the purposes of improving the effect of splashing slag for protecting the furnace and maintaining the furnace bottom are achieved. The phrase "the slag is scarce at the taphole in step S3 means that less than 2kg of slag is splashed per minute.
Preferably, the medium-high magnesium dolomite comprises 14-20% by mass of MgO, 36-45% by mass of CaO and 5-35 mm in particle size.
More preferably, the medium-high magnesium dolomite comprises 14% by mass of MgO and 36% by mass of CaO, and the grain size of the medium-high magnesium dolomite is 10-20 mm.
Preferably, in the step S3, the nitrogen pressure is controlled to be 0.5-1.5 MPa in the first 1.5min during the slag splashing operation; controlling the nitrogen pressure to be 0.2-1.0 MPa after 1.5 min.
More preferably, the nitrogen pressure is controlled to be 1.0MPa in the first 1.5min in the slag splashing operation process; after 1.5min the sigh pressure was controlled to 0.8 MPa.
Preferably, in the step S3, the distance between the oxygen lance and the furnace bottom is 3.3-3.5 m before 1.5min in the slag splashing operation process; when the furnace mouth jumps out of granular slag, moving the oxygen lance to 2.6-2.8 m away from the furnace bottom, and keeping the oxygen lance 2.6-2.8 m away from the furnace bottom to splash slag for 1.5 min; when the furnace mouth jumps out of the furnace slag and becomes thinner, the oxygen lance is moved to 3.3-3.5 m.
Preferably, after the slag splashing operation, the converter is kept still for 5-7 min.
Preferably, in the step S2, the amount of the medium-high magnesium dolomite added is 2/3 of the total amount of the medium-high magnesium dolomite added.
Preferably, in the step S3, slag splashing is performed for 25 to 35 seconds after the medium-high magnesium dolomite is added.
Compared with the prior art, the invention has the following technical effects:
the invention discloses a converter bottom protection method, which adopts the step of adding medium-high magnesium dolomite, and the pressure control of slag splashing and the position control of an oxygen lance. The slag splashing layer and the covering layer formed by splashing slag have better corrosion resistance, can inhibit the oxidation and decarburization of the surface of the lining brick at the bottom of the furnace, can reduce the soaking and melting loss of high-temperature molten steel on the lining brick at the bottom of the furnace, thereby protecting the lining brick at the bottom of the furnace, prolonging the service time of the converter and reducing the maintenance cost of the converter.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below with reference to specific examples and comparative examples. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
Unless otherwise specified, the devices used in the present examples, comparative examples and experimental examples were all conventional experimental devices, the materials and reagents used were commercially available without specific reference, and the experimental methods without specific reference were also conventional experimental methods.
EXAMPLE 1 method for protecting converter bottom
The method for protecting the converter bottom of the converter by using a 120-ton converter example comprises the following specific steps:
s1, controlling the tapping temperature at the blowing terminal point of a converter before tapping to be 1645 ℃, and controlling the oxygen content in molten steel to be 500 ppm. When the converter taps steel, the molten steel is completely discharged, the slag is left in the converter, and the amount of the slag is controlled to be about 6 t-8 t; after tapping, the furnace is rocked to the zero position (the charging angle of the converter);
s2, adding 1000kg of medium-high magnesium dolomite into the furnace bottom protection plan. Firstly, adding 670kg of slag splashing oxygen lance before descending the lance of the converter;
s3, after adding medium-high magnesium dolomite, operating the converter to shake at 30 degrees forwards and backwards respectively to enable part of the dolomite entering the converter to sink to the position of the bottom of the converter and play a role in reducing the temperature of low-melting slag; when slag splashing occurs for 60s, 400kg of coke is added for deoxidation operation, and when slag jumping out from a furnace mouth is rare, 330kg of medium-high magnesium dolomite is added.
Wherein, a converter oxygen lance is used for slag splashing operation, the pressure of nitrogen supply is set to be 0.8 MPa-1.0 MPa, the early stage of slag splashing is 1.5 minutes, and the pressure of slag splashing nitrogen is controlled according to 1.0 MPa; in the middle and later slag splashing periods, the nitrogen pressure of slag splashing is controlled at 0.8MPa, and the slag splashing time is 2 min.
In the first 1.5 minutes of slag splashing operation, the position of a slag splashing oxygen lance is controlled to be 2.0-2.2 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 3.3-3.5 m; when the converter mouth jumps out of the granular slag, the oxygen lance can be gradually reduced to 1.3-1.5 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 2.6-2.8 m; and when the slag density jumping out of the furnace mouth gradually falls down, the slag splashing lance position is lifted to 2.0m (relative lance position), namely the slag is splashed for 30 seconds at the position between the oxygen lance and 3.3m at the bottom of the converter, and then the slag splashing operation is finished.
The medium-high magnesium dolomite comprises 20 mass percent of MgO, 36 mass percent of CaO and 5mm granularity, and is not mixed with soil and other impurities (such as a mountain skin, miscellaneous stones, honeycomb-shaped ores and other impurity inclusions).
And after the slag splashing operation is finished, finishing the furnace bottom protection operation, and standing and maintaining the converter for 5-7 minutes.
Example 2 converter bottom protection method
The method for protecting the converter bottom of the converter by using a 120-ton converter example comprises the following specific steps:
s1, controlling the tapping temperature at the blowing terminal point of a converter before tapping at 1660 ℃, and controlling the oxygen content in molten steel at 700 ppm. When the converter taps steel, the molten steel is completely discharged, the slag is left in the converter, and the amount of the slag is controlled to be about 6 t-8 t; after tapping, the furnace is rocked to the zero position (the charging angle of the converter);
s2, adding 1200Kg of medium and high magnesium dolomite into the furnace bottom protection plan. Firstly, adding about 600kg of slag splashing oxygen lance before descending the lance;
s3, after adding medium-high magnesium dolomite, operating the converter to shake at 30 degrees forwards and backwards respectively to enable part of the dolomite entering the converter to sink to the position of the bottom of the converter and play a role in reducing the temperature of low-melting slag; 530kg of coke is added for deoxidation operation when slag splashing is carried out for 55s, and 600kg of medium-high magnesium dolomite is added when the slag jumping out from a furnace mouth is less than 2 kg/min.
Wherein, a converter oxygen lance is used for slag splashing operation, the pressure of nitrogen supply is set to be 0.2 MPa-1.5 mpMPa, the early stage of slag splashing is 1.5 minutes, and the pressure of slag splashing nitrogen is controlled according to 1.5 MPa; in the middle and later slag splashing periods, the nitrogen pressure of slag splashing is controlled according to 1.0MPa, and the slag splashing time is 2 min.
In the first 1.5 minutes of slag splashing operation, the position of a slag splashing oxygen lance is controlled to be 2.0-2.2 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 3.3-3.5 m; when the converter mouth jumps out of the granular slag, the oxygen lance can be gradually reduced to 1.3-1.5 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 2.6-2.8 m; and when the slag density jumping out of the furnace mouth gradually falls down, the slag splashing lance position is lifted to 2.0m (relative lance position), namely the slag is splashed for 30 seconds at the position between the oxygen lance and 3.3m at the bottom of the converter, and then the slag splashing operation is finished.
And after the slag splashing operation is finished, finishing the furnace bottom protection operation, and standing and maintaining the converter for 5-7 minutes.
The medium-high magnesium dolomite comprises 14 mass percent of MgO, 3645 mass percent of CaO and 35mm of granularity, and is not mixed with soil and other impurities (such as a hill skin, miscellaneous stones, honeycomb-shaped ores and other impurity inclusions).
Example 3 converter bottom protection method
The method for protecting the converter bottom of the converter by using a 120-ton converter example comprises the following specific steps:
s1, controlling the tapping temperature at the blowing terminal point of a converter before tapping to be 1690 ℃, and controlling the oxygen content in molten steel to be 900 ppm. When the converter taps steel, the molten steel is completely discharged, the slag is left in the converter, and the amount of the slag is controlled to be about 6 t-8 t; after tapping, the furnace is rocked to the zero position (the charging angle of the converter);
s2, adding 1800kg of medium-high magnesium dolomite into the furnace bottom protection plan. Firstly, adding about 1500kg of slag splashing oxygen lance before descending the lance of the converter;
s3, after adding medium-high magnesium dolomite, operating the converter to shake at 30 degrees forwards and backwards respectively to enable part of the dolomite entering the converter to sink to the position of the bottom of the converter and play a role in reducing the temperature of low-melting slag; 700kg of coke is added for deoxidation operation when slag is splashed for 70s, and 300kg of medium-high magnesium dolomite is added when slag jumping out of a furnace mouth is rare.
Wherein, a converter oxygen lance is used for slag splashing operation, the pressure of nitrogen supply is set to be 0.2 MPa-1.5 MPa, the early stage of slag splashing is 1.5 minutes, and the pressure of slag splashing nitrogen is controlled according to 0.5 MPa; in the middle and later slag splashing periods, the nitrogen pressure of slag splashing is controlled at 0.2MPa, and the slag splashing time is 2 min.
In the first 1.5 minutes of slag splashing operation, the position of a slag splashing oxygen lance is controlled to be 2.0-2.2 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 3.3-3.5 m; when the converter mouth jumps out of the granular slag, the oxygen lance can be gradually reduced to 1.3-1.5 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 2.6-2.8 m; and when the slag density jumping out of the furnace mouth gradually falls down, the slag splashing lance position is lifted to 2.0m (relative lance position), namely the slag is splashed for 30 seconds at the position between the oxygen lance and 3.3m at the bottom of the converter, and then the slag splashing operation is finished.
And after the slag splashing operation is finished, finishing the furnace bottom protection operation, and standing and maintaining the converter for 5-7 minutes.
The medium-high magnesium dolomite comprises 18 mass percent of MgO, 40 mass percent of CaO and 20mm granularity, and is not mixed with soil and other impurities (such as a mountain skin, miscellaneous stones, honeycomb-shaped ores and other impurity inclusions).
Comparative example 1 method for protecting converter bottom
The method for protecting the converter bottom of the converter by using a 120-ton converter example comprises the following specific steps:
s1, controlling the tapping temperature at the blowing terminal point of a converter before tapping to be 1645 ℃, and controlling the oxygen content in molten steel to be 500 ppm. When the converter taps steel, the molten steel is completely discharged, the slag is left in the converter, and the amount of the slag is controlled to be about 6 t-8 t; after tapping, the furnace is rocked to the zero position (the charging angle of the converter);
s2, adding 1000kg of medium-high magnesium dolomite into the furnace bottom protection plan. 1000kg of medium-high magnesium dolomite is added at one time;
s3, after adding medium-high magnesium dolomite, operating the converter to shake at 30 degrees forwards and backwards respectively to enable part of the dolomite entering the converter to sink to the position of the bottom of the converter and play a role in reducing the temperature of low-melting slag; when slag splashing occurs for 60s, 400kg of coke is added for deoxidation operation.
Wherein, a converter oxygen lance is used for slag splashing operation, the pressure of nitrogen supply is set to be 0.8 MPa-1.0 MPa, the early stage of slag splashing is 1.5 minutes, and the pressure of slag splashing nitrogen is controlled according to 1.0 MPa; in the middle and later slag splashing periods, the nitrogen pressure of slag splashing is controlled at 0.8MPa, and the slag splashing time is 2 min.
In the first 1.5 minutes of slag splashing operation, the position of a slag splashing oxygen lance is controlled to be 2.0-2.2 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 3.3-3.5 m; when the converter mouth jumps out of the granular slag, the oxygen lance can be gradually reduced to 1.3-1.5 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 2.6-2.8 m; and when the slag density jumping out of the furnace mouth gradually falls down, the slag splashing lance position is lifted to 2.0m (relative lance position), namely the slag is splashed for 30 seconds at the position between the oxygen lance and 3.3m at the bottom of the converter, and then the slag splashing operation is finished.
And after the slag splashing operation is finished, finishing the furnace bottom protection operation, and standing and maintaining the converter for 5-7 minutes.
The medium-high magnesium dolomite comprises 20 mass percent of MgO, 36 mass percent of CaO and 5mm granularity, and is not mixed with soil and other impurities (such as a mountain skin, miscellaneous stones, honeycomb-shaped ores and other impurity inclusions).
Compared with example 1, the comparative example is different from example 1 in that medium-high magnesium dolomite is added into the converter at one time, and the rest is the same as example 1.
Comparative example 2 bottom protection method for converter
The method for protecting the converter bottom of the converter by using a 120-ton converter example comprises the following specific steps:
s1, controlling the tapping temperature at the blowing terminal point of a converter before tapping to be 1645 ℃, and controlling the oxygen content in molten steel to be 500 ppm. When the converter taps steel, the molten steel is completely discharged, the slag is left in the converter, and the amount of the slag is controlled to be about 6 t-8 t; after tapping, the furnace is rocked to the zero position (the charging angle of the converter);
s2, adding 1000Kg of medium and high magnesium dolomite into the furnace bottom protection plan. Firstly, about 330kg of slag splashing oxygen lance is added before descending the lance of the converter;
s3, after adding medium-high magnesium dolomite, operating the converter to shake at 30 degrees forwards and backwards respectively to enable part of the dolomite entering the converter to sink to the position of the bottom of the converter and play a role in reducing the temperature of low-melting slag; when slag splashing occurs for 60s, 400kg of coke is added for deoxidation operation, and when slag jumping out from a furnace mouth is rare, 670kg of medium-high magnesium dolomite is added.
Wherein, a converter oxygen lance is used for slag splashing operation, the pressure of nitrogen supply is set to be 0.8 MPa-1.0 MPa, the early stage of slag splashing is 1.5 minutes, and the pressure of slag splashing nitrogen is controlled according to 1.0 MPa; in the middle and later slag splashing periods, the nitrogen pressure of slag splashing is controlled at 0.8MPa, and the slag splashing time is 2 min.
In the first 1.5 minutes of slag splashing operation, the position of a slag splashing oxygen lance is controlled to be 2.0-2.2 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 3.3-3.5 m; when the converter mouth jumps out of the granular slag, the oxygen lance can be gradually reduced to 1.3-1.5 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 2.6-2.8 m; and when the slag density jumping out of the furnace mouth gradually falls down, the slag splashing lance position is lifted to 2.0m (relative lance position), namely the slag is splashed for 30 seconds at the position between the oxygen lance and 3.3m at the bottom of the converter, and then the slag splashing operation is finished.
And after the slag splashing operation is finished, the furnace bottom protection operation is finished. And standing and maintaining the converter for 5-7 minutes.
The medium-high magnesium dolomite comprises 20 mass percent of MgO, 36 mass percent of CaO and 5mm granularity, and is not mixed with soil and other impurities (such as a mountain skin, miscellaneous stones, honeycomb-shaped ores and other impurity inclusions).
Compared with the example 1, the comparative example has 330kg of medium-high magnesium dolomite added in the step S2 and 670kg of medium-high magnesium dolomite added in the step S3, and the other steps are the same as the example 1.
Comparative example 3 bottom protection method for converter
The method for protecting the converter bottom of the converter by using a 120-ton converter example comprises the following specific steps:
s1, controlling the tapping temperature at the blowing terminal point of a converter before tapping to be 1645 ℃, and controlling the oxygen content in molten steel to be 500 ppm. When the converter taps steel, the molten steel is completely discharged, the slag is left in the converter, and the amount of the slag is controlled to be about 6 t-8 t; after tapping, the furnace is rocked to the zero position (the charging angle of the converter);
s2, adding 1000Kg of medium and high magnesium dolomite into the furnace bottom protection plan. Firstly, adding 670kg of slag splashing oxygen lance before descending the lance of the converter;
s3, after adding medium-high magnesium dolomite, operating the converter to shake at 30 degrees forwards and backwards respectively to enable part of the dolomite entering the converter to sink to the position of the bottom of the converter and play a role in reducing the temperature of low-melting slag; when slag splashing occurs for 60s, 400kg of coke is added for deoxidation operation, and when slag jumping out from a furnace mouth is rare, 330kg of medium-high magnesium dolomite is added.
Wherein, a converter oxygen lance is used for slag splashing operation, the pressure of nitrogen supply is set to be 0.8 MPa-1.0 MPa, the early stage of slag splashing is 1.5 minutes, and the pressure of slag splashing nitrogen is controlled according to 1.0 MPa; in the middle and later slag splashing periods, the nitrogen pressure of slag splashing is controlled at 0.8MPa, and the slag splashing time is 2 min.
In the first 1.5 minutes of slag splashing operation, the position of a slag splashing oxygen lance is controlled to be 2.0-2.2 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 3.3-3.5 m; when the converter mouth jumps out of the granular slag, the oxygen lance can be gradually reduced to 1.3-1.5 m (relative lance position), namely the distance between the oxygen lance and the bottom of the converter is 2.6-2.8 m; and when the slag density jumping out of the furnace mouth gradually falls down, the slag splashing lance position is lifted to 2.0m (relative lance position), namely the slag is splashed for 30 seconds at the position between the oxygen lance and 3.3m at the bottom of the converter, and then the slag splashing operation is finished.
After the slag splashing operation is finished, the furnace bottom protection operation is finished, and scrap steel and molten iron can be immediately added for steelmaking.
The medium-high magnesium dolomite comprises 20 mass percent of MgO, 36 mass percent of CaO and 5mm granularity, and is not mixed with soil and other impurities (such as a mountain skin, miscellaneous stones, honeycomb-shaped ores and other impurity inclusions).
Compared with the example 1, the steel making is carried out by adding scrap steel and molten iron immediately after the slag splashing of the comparative example is finished.
Experimental example 1
The same degree of corrosion was measured for the same time by maintaining the same degree of corrosion in the converter using the method of example and comparative example, respectively.
TABLE 1 degree of corrosion of the converter by different converter bottom protection methods
| Time | 30 days | 45 days | 60 days | 90 days | 120 days |
| Example 1 | 1121mm | 1102mm | 997mm | 1007mm | 1005mm |
| Example 2 | 997mm | 982mm | 990mm | 917mm | 875mm |
| Example 3 | 960mm | 910mm | 901mm | 870mm | 834mm |
| Comparative example 1 | 987mm | 942mm | 916mm | 870mm | 853mm |
| Comparative example 2 | 990mm | 972mm | 941mm | 906mm | 886mm |
| Comparative example 3 | 950mm | 923mm | 897mm | 830mm | 817mm |
Remarking: the above is the measurement data for measuring the furnace bottom of the converter in the middle age
As is clear from Table 1, the converter treated by the bottom-protecting method of the example group was less corroded at the same time, indicating that the method of the present invention is effective in prolonging the service life of the converter.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims (10)
1. A method for protecting the bottom of a converter is characterized by comprising the following steps:
s1, after converter tapping, the amount of slag left in the converter is 50-65 kg/tSteel；
S2, adding medium-high magnesium dolomite into the converter, and then carrying out rocking at 25-35 degrees in front and at back, wherein the amount of the added medium-high magnesium dolomite is 1/2-5/6 of the total amount of the added medium-high magnesium dolomite in the step;
s3, blowing nitrogen through an oxygen lance to perform slag splashing protection, adding coke to perform deoxidation operation when slag splashing lasts for 55-70 s, adding 1/6-1/2 of the total addition of medium and high magnesium dolomite when slag jumping out of a furnace mouth is rare, and then splashing slag for 20-40 s;
wherein when the temperature of converter tapping is 1630-1650 ℃, the oxygen content at the end point is more than 400ppm, the slag amount after tapping is 7.6-8.5 t, and the total addition amount of medium-high magnesium dolomite is 8-9 kg/tSteel(ii) a The total adding amount of the coke is 3-4 kg/tSteel；
When the tapping temperature of the converter is 1650-1680 ℃, and the oxygen content at the end point is more than 600ppm, the slag remaining amount after tapping is 5.4-7 tSteelWhen the total adding amount of the medium-high magnesium dolomite is 8.5kg to 12.5kg/tSteel(ii) a The coke addition was 4.2kg/tSteel；
When the temperature of the converter tapping is more than 1680 ℃, the oxygen content at the end point is more than 800ppm, and the slag amount after tapping is 5.2-7 t, the addition amount of the medium-high magnesium dolomite is 12.5-16.6 kg/tSteel(ii) a The adding amount of the coke is 4.8-6 kg/tSteel。
2. The method for protecting the bottom of the converter according to claim 1, wherein the medium-high magnesium dolomite comprises 14-20% by mass of MgO, 36-45% by mass of CaO and 5-35 mm in particle size.
3. The method for protecting the bottom of the converter according to claim 2, wherein the medium-high magnesium dolomite comprises 14% by mass of MgO and 36% by mass of CaO.
4. The converter bottom protection method of claim 2, wherein the medium-high magnesium dolomite has a particle size of 10-20 mm.
5. The method for protecting the bottom of the converter according to claim 1, wherein in step S3, the nitrogen pressure is controlled to be 0.5-1.5 MPa for the first 1.5min during the slag splashing operation; controlling the nitrogen pressure to be 0.2-1.0 MPa after 1.5 min.
6. The method for protecting the bottom of the converter according to claim 5, wherein in step S3, the nitrogen pressure is controlled to be 1.0MPa for the first 1.5min during the slag splashing operation; after 1.5min the sigh pressure was controlled to 0.8 MPa.
7. The method for protecting the bottom of the converter according to claim 1, wherein in step S3, the distance between the oxygen lance and the bottom of the converter is 3.3-3.5 m before 1.5min during the slag splashing operation; when the furnace mouth jumps out of granular slag, moving the oxygen lance to 2.6-2.8 m away from the furnace bottom, and keeping the oxygen lance 2.6-2.8 m away from the furnace bottom to splash slag for 1.5 min; when the furnace mouth jumps out of the furnace slag and becomes thinner, the oxygen lance is moved to 3.3-3.5 m.
8. The method for protecting the bottom of the converter according to claim 1, wherein the converter is left to stand and maintained for 5 to 7 minutes after the slag splashing operation.
9. The converter bottom protection method of claim 1, wherein in step S2, the amount of the medium-high magnesium dolomite added is 2/3 of the total amount of the medium-high magnesium dolomite added.
10. The method for protecting the bottom of the converter according to claim 1, wherein in the step S3, slag splashing is performed for 25-35 seconds after medium-high magnesium dolomite is added.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113265504A (en) * | 2021-05-19 | 2021-08-17 | 新疆八一钢铁股份有限公司 | Operation method for splashing double slag of converter |
| CN112853033B (en) * | 2021-03-10 | 2023-10-13 | 柳州钢铁股份有限公司 | Efficient slag splashing intelligent control method and system based on furnace mouth image analysis |
| CN118480638A (en) * | 2024-06-14 | 2024-08-13 | 本溪北营钢铁（集团）股份有限公司 | A method for slagging converter by shaking furnace |
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| CN118480638A (en) * | 2024-06-14 | 2024-08-13 | 本溪北营钢铁（集团）股份有限公司 | A method for slagging converter by shaking furnace |
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