CN115341068B - Slag splashing furnace protection method - Google Patents
Slag splashing furnace protection method Download PDFInfo
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- CN115341068B CN115341068B CN202211037937.7A CN202211037937A CN115341068B CN 115341068 B CN115341068 B CN 115341068B CN 202211037937 A CN202211037937 A CN 202211037937A CN 115341068 B CN115341068 B CN 115341068B
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- 239000002893 slag Substances 0.000 title claims abstract description 221
- 238000000034 method Methods 0.000 title claims abstract description 45
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 111
- 239000010959 steel Substances 0.000 claims abstract description 111
- 229910000514 dolomite Inorganic materials 0.000 claims abstract description 21
- 239000010459 dolomite Substances 0.000 claims abstract description 21
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 19
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 19
- 239000004571 lime Substances 0.000 claims abstract description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 47
- 229910052757 nitrogen Inorganic materials 0.000 claims description 19
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 15
- 239000011777 magnesium Substances 0.000 claims description 15
- 229910052749 magnesium Inorganic materials 0.000 claims description 15
- 238000007664 blowing Methods 0.000 claims description 13
- 230000000694 effects Effects 0.000 claims description 11
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 8
- 238000004544 sputter deposition Methods 0.000 claims description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 12
- 229910052742 iron Inorganic materials 0.000 abstract description 5
- 238000010079 rubber tapping Methods 0.000 abstract description 5
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 4
- 229910052717 sulfur Inorganic materials 0.000 abstract description 3
- 238000001179 sorption measurement Methods 0.000 abstract 1
- 239000011449 brick Substances 0.000 description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- 230000001590 oxidative effect Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- 238000009628 steelmaking Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 230000002349 favourable effect Effects 0.000 description 4
- 230000004907 flux Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 238000010926 purge Methods 0.000 description 4
- 239000011819 refractory material Substances 0.000 description 4
- 238000003723 Smelting Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000010835 comparative analysis Methods 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005262 decarbonization Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009851 ferrous metallurgy Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 239000000126 substance Substances 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
-
- 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
-
- 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
- Y02P10/20—Recycling
Abstract
The application provides a slag splashing furnace protection method which is suitable for slag splashing furnace protection under the condition of low unit consumption of molten iron. The method for protecting the slag splashing furnace comprises the following steps: acquiring the temperature of molten steel covered by slag in a converter; when the temperature of the molten steel is higher than 1640 ℃, adding 1.8-2.3 kg/ton of lime and 1.8-2.3 kg/ton of raw dolomite into a converter at the end point of converting to obtain first slag; after pouring out the molten steel, the balance of the first slag in the converter is 55-72 kg/ton of steel; adding 0.8-1.2 kg of raw dolomite per ton of steel into the rest first slag to obtain second slag; the second slag is sputtered onto the lining of the converter. According to the slag forming device, lime and raw dolomite are added into slag, so that the alkalinity and viscosity of the slag are improved, the slag temperature is reduced, the purpose of thick slag tapping can be achieved, the adsorption capacity of slag on the surface of molten steel to residual elements P and S can be improved, the slag is easier to hang on a furnace lining during slag splashing, and the bonding layer of the slag and the furnace lining is firmer.
Description
Technical Field
The application relates to the technical field of ferrous metallurgy, in particular to a slag splashing furnace protection method.
Background
The slag splashing furnace protection technology is to utilize the steelmaking end slag with saturated or supersaturated MgO content, and through high-pressure splashing, cool and solidify the slag to form a layer of high-melting-point slag layer on the surface of the furnace lining, and adhere well with the furnace lining. The slag splashing layer formed by the slag splashing has better corrosion resistance, can inhibit oxidation and decarbonization on the surface of the furnace lining brick, and can reduce erosion and scouring of high-temperature slag to the furnace lining brick, thereby protecting the furnace lining brick, reducing the loss speed of refractory materials, reducing the consumption of gunning materials, simultaneously reducing the labor intensity of workers, prolonging the service life of the furnace lining, improving the operation rate of a converter and reducing the production cost.
The slag splashing furnace protection is a routine operation in production at present and is a main means for maintaining a furnace lining. The slag splashing furnace protection technology can greatly improve the furnace life of the converter, so that the slag splashing furnace protection technology is commonly adopted in the converter in China, and the furnace life of the converter is improved to more than 10000 from the former 3000-6000 furnaces. The service life of the converter is improved, the consumption of the converter steelmaking refractory material is reduced, the resources are saved, and the utilization rate and the steel yield of the converter are improved.
In order to maintain or improve the steel yield, most steel plants at the present stage adopt a method for improving the addition amount of converter scrap steel to reduce the unit consumption of molten iron. The method not only can stabilize the steel yield, but also can rapidly reduce the smelting cost. However, after the steel scrap ratio is increased, the oxidizing property of the slag at the end point of converter blowing is increased, the slag at the end point is thin, the viscosity is low, the slag layer is thin, the combination of the slag and the furnace lining bricks is weak, the melting temperature of the slag is low, corrosion resistance is not realized, the slag splashing protection effect of the converter is poor, and the service life of the furnace lining of the converter is reduced, so that the conventional slag splashing protection method is not suitable for the converter condition under the condition of low molten iron unit consumption.
Disclosure of Invention
In view of the above, the present application provides a method for slag splashing protection in order to adapt to slag splashing protection under the condition of low unit consumption of molten iron.
The slag splashing furnace protection method provided by the application comprises the following steps:
acquiring the temperature of molten steel covered by slag in a converter;
when the temperature is higher than 1640 ℃, adding 1.8 kg/ton steel to 2.3 kg/ton steel and 1.8 kg/ton steel to 2.3 kg/ton steel of raw dolomite into a converter at the end point of converting to obtain first slag;
after pouring out the molten steel, the balance of the first slag in the converter is 55 kg/ton steel to 72 kg/ton steel;
adding 0.8 kg/ton steel to 1.2 kg/ton steel of raw dolomite into the rest first slag to obtain second slag;
the second slag is sputtered onto the lining of the converter.
Optionally, after obtaining the temperature of molten steel covered by slag in the converter, the method further comprises:
when the temperature is not higher than 1640 ℃, pouring out part of slag at the end of converting, so that the balance of slag is 25 kg/ton steel to 40 kg/ton steel;
adding 1.8 kg/ton steel to 2.3 kg/ton steel of lime and 1.8 kg/ton steel to 2.3 kg/ton steel of magnesium balls into the converter to obtain third slag;
and after pouring out the molten steel, sputtering third slag onto the furnace lining of the converter.
Optionally, after sputtering the third slag to the lining of the converter, the method further comprises:
when the slag splashing is finished and the gun is ready to be started, 4.4 kg/ton of lime-5.6 kg/ton of steel is added to be used as a backing material.
Optionally, the physicochemical property parameters of lime include: the mass percentage of CaO is more than or equal to 90%, the activity degree is more than or equal to 360, the ignition loss is less than or equal to 5%, and the proportion of the part with the granularity of 10 mm-60 mm is at least 90%.
Optionally, the parameters of the magnesium sphere include: the mass percentage of MgO is more than or equal to 70%, the mass percentage of CaO is not more than 4.5% and not less than 1.5%, and the proportion of the part with the granularity of 5 mm-50 mm is more than or equal to 90%.
Optionally, the parameters of raw dolomite include: the mass percent of MgO is more than or equal to 18.5 percent, the mass percent of MgO plus CaO is more than or equal to 51 percent, and the proportion of the part with the granularity of 5 mm-30 mm is more than or equal to 90 percent.
Optionally, the splash slag adopts a nitrogen blowing mode, the pressure of nitrogen is controlled to be 1.10 MPa-1.35 MPa in the operation process, and the flow rate of the nitrogen is 27000m 3 /h～30000m 3 /h。
Optionally, the nitrogen gas flow moves up and down in the slag splashing operation process, and before slag splashes out of the mouth of the converter, the nitrogen gas flow moves between 0cm and 100cm to promote slag lifting, and after slag lifting, the nitrogen gas flow moves between 20cm and 60 cm.
Optionally, the sputtering time of the slag is 1.5-3.5 min, and the slag lifting time is 0.5-1.5 min.
Compared with the prior art, the application has the following beneficial effects:
according to the method, a proper slag regulating method is selected according to the value of the temperature of molten steel covered by slag in the converter, when the temperature of the molten steel is higher than 1640 ℃, lime 1.8-2.3 kg/ton of steel and raw dolomite 1.8-2.3 kg/ton of steel are added into the converter at the end point of blowing, the alkalinity of the slag is improved after the addition, and the slag temperature is reduced. The high alkalinity is favorable for capturing P, S, the reduction of the slag temperature is favorable for improving the viscosity of slag, the high viscosity improves the surface tension of slag, the phenomenon that slag flows out along with molten steel is avoided when molten steel is poured out, slag is easier to hang on a furnace lining when the slag is splashed, the slag splashing furnace protection effect is improved, and the bonding layer of the slag and a furnace lining brick is firmer.
Detailed Description
In order to make the application purposes, technical solutions and beneficial technical effects of the present application clearer, the present application is further described in detail below with reference to examples. It should be understood that the embodiments described in this specification are for purposes of illustration only and are not intended to limit the present application.
For simplicity, only a few numerical ranges are explicitly disclosed in this application. However, any lower limit may be combined with any upper limit to form a range not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and any upper limit may be combined with any other upper limit to form a range not explicitly recited. Furthermore, each point or individual value between the endpoints of the range is included within the range, although not explicitly recited. Thus, each point or individual value may be combined as a lower or upper limit on itself with any other point or individual value or with other lower or upper limit to form a range that is not explicitly recited.
In the description of the present application, unless otherwise indicated, "above" and "below" are intended to include the present number, and the meaning of "multiple" in "one or more" means two or more.
The above summary of the present application is not intended to describe each disclosed embodiment or every implementation of the present application. The following description more particularly exemplifies illustrative embodiments. Guidance is provided throughout this application by a series of embodiments, which may be used in various combinations. In the various examples, the list is merely a representative group and should not be construed as exhaustive.
While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
The slag splashing furnace protection is a routine operation in production at present and is a main means for maintaining a furnace lining. The slag splashing furnace protection technology can greatly improve the furnace life of the converter, so that the slag splashing furnace protection technology is commonly adopted in the converter in China, and the furnace life of the converter is improved to more than 10000 from the former 3000-6000 furnaces. The service life of the converter is improved, the consumption of the converter steelmaking refractory material is reduced, the resources are saved, and the utilization rate and the steel yield of the converter are improved.
In order to maintain or improve the steel yield, most steel plants at the present stage adopt a method for improving the addition amount of converter scrap steel to reduce the unit consumption of molten iron. The method not only can stabilize the steel yield, but also can rapidly reduce the smelting cost. However, after the steel scrap ratio is increased, the oxidizing property of the slag at the end point of converter blowing is increased, the slag at the end point is thin, the viscosity is low, the slag layer is thin, the combination of the slag and the furnace lining bricks is weak, the melting temperature of the slag is low, corrosion resistance is not realized, the slag splashing protection effect of the converter is poor, and the service life of the furnace lining of the converter is reduced, so that the conventional slag splashing protection method is not suitable for the converter condition under the condition of low molten iron unit consumption.
In view of the above, the inventor of the present application has provided a method for protecting a converter from slag splashing through experimental analysis, and the method is aimed at providing a method for protecting a converter from slag splashing, which is suitable for a converter with low unit consumption of molten iron.
The slag splashing furnace protection method provided by the application comprises the following steps:
acquiring the temperature of molten steel covered by slag in a converter;
when the temperature of the molten steel is higher than 1640 ℃, adding 1.8 kg/ton steel to 2.3 kg/ton steel and 1.8 kg/ton steel to 2.3 kg/ton steel of raw dolomite into a converter at the converting end point to obtain first slag;
after pouring out the molten steel, the balance of the first slag in the converter is 55 kg/ton steel to 72 kg/ton steel;
adding 0.8 kg/ton steel to 1.2 kg/ton steel of raw dolomite into the rest first slag to obtain second slag;
the second slag is sputtered onto the lining of the converter.
In the embodiment of the application, the addition amount of lime and dolomite and the residual amount of slag in the converter are calculated by the mass of molten steel in the converter before the molten steel is poured out.
CaCO in raw dolomite 3 And MgCO 3 The CaO and MgO are generated by decomposition to adjust the alkalinity and MgO content in the slag, the quantity of high-melting-point solid-phase substances in the slag is increased, the low-melting-point compound is reduced, and the slag is sticky and is easy to adhere to the surface of a furnace lining brick of the converter, so that a high-melting-point slag splashing layer is formed on the surface of the furnace lining brick.
According to the embodiment of the application, the raw dolomite is added before molten steel is poured out, so that the temperature of the molten steel can be reduced, 0.8 kg/ton steel to 1.2 kg/ton steel is added into the converter after the molten steel is poured out, namely the raw dolomite is added twice, and the influence on the quality of the molten steel caused by too fast temperature reduction of the molten steel in the converter can be avoided. The balance of 55 kg/ton steel to 72 kg/ton steel can realize that slag remains to protect the converter bottom after the slag splashing operation is completed.
After the steel scrap ratio is improved in steelmaking, the oxidizing property of slag is increased at the end point of converter blowing, the end point temperature is high, the slag is thin, the viscosity is low, the slag splashing layer is thin, the combination of the slag and the furnace lining bricks is weak, the slag melting temperature is low, corrosion resistance is poor, the slag splashing protection effect of the converter is poor, and the service life of the furnace lining of the converter is reduced. According to the embodiment of the application, a proper slag regulating method is selected according to the value of the temperature of molten steel covered by slag in the converter, when the temperature of the molten steel is in a range higher than 1640 ℃, the superheat degree of the molten steel is higher, and 1.8 kg/ton steel-2.3 kg/ton steel of raw dolomite are added into the converter at the blowing end point, so that the alkalinity of slag is improved, and the slag temperature is reduced. The high alkalinity is favorable for capturing P, S, the reduction of the slag temperature is favorable for improving the viscosity of slag, the high viscosity improves the surface tension of slag, the phenomenon that slag flows out along with molten steel is avoided when molten steel is poured out, slag is easier to hang on a furnace lining when the slag is splashed, the slag splashing furnace protection effect is improved, and the bonding layer of the slag and a furnace lining brick is firmer. Because FeO has great aggressivity to bricks, the addition of lime and dolomite reduces the oxidability of slag, so that the bonding layer of slag and lining bricks is firmer, thereby improving the furnace life of the converter, reducing the consumption of the converter steelmaking refractory material, saving resources and improving the utilization rate and steel yield of the converter.
In some embodiments, after obtaining the temperature of molten steel covered by slag in the converter, the method further comprises:
when the temperature of the molten steel is not higher than 1640 ℃, pouring out part of slag at the end of blowing, so that the balance of slag is 25 kg/ton steel to 40 kg/ton steel;
adding 1.8 kg/ton steel to 2.3 kg/ton steel of lime and 1.8 kg/ton steel to 2.3 kg/ton steel of magnesium balls into the converter to obtain third slag;
and after pouring out the molten steel, sputtering third slag onto the furnace lining of the converter.
When the temperature of molten steel is within a range not exceeding 1640 ℃, the superheat degree of the temperature of the molten steel is not high at the moment, and according to the embodiment of the application, after a part of slag is poured out, magnesium balls are added, so that the adding amount of slag charge can be greatly reduced, and further the loss of the slag charge to the temperature during adding is reduced.
According to the embodiment of the application, the slag remaining amount is not too small or too large, so that slag after lime and magnesium balls are added later is too viscous, the temperature of the slag is reduced quickly and is easy to crust, too much slag is not thick, after part of slag is poured out, the magnesium source is magnesium balls with higher MgO content, and because more slag is poured out, the flux is required to be melted quickly when the flux is added, and the magnesium balls play a role of fluxing agent and slag forming. The magnesium balls have higher MgO content, are more beneficial to fluxing, and can realize the effect of thick slag by a small amount. In addition, when the slag oxidizing property is higher, the use efficiency of the flux added in the later stage can be improved by pouring out part of the slag and then adding the flux, and the slag oxidizing property can be reduced more quickly. Part of slag is poured out, and the risk of phosphorus return of the slag can be reduced.
In some embodiments, after sputtering the third slag to the lining of the converter, the method further comprises: when the slag splashing is finished and the gun is ready to be started, 4.4 kg/ton of lime-5.6 kg/ton of steel is added to be used as a backing material.
According to the embodiment of the application, after the third slag is sputtered to the furnace lining of the converter, the residual slag in the converter is less, and the lime is added to avoid damage to the furnace bottom when reinforcing scrap steel of the converter.
In some embodiments, the physicochemical properties of lime include: the mass percentage of CaO is more than or equal to 90%, the activity degree is more than or equal to 360, the ignition loss is less than or equal to 5%, and the proportion of the part with the granularity of 10 mm-60 mm is at least 90%.
According to the embodiment of the application, the physicochemical property parameters of the lime are in the proper range, so that the consumption of the lime can be reduced, the reduction value of the temperature of molten steel in the converter is reduced, the melting speed can be increased in the proper range, and the slag splashing furnace protection time is shortened.
In some embodiments, the parameters of the magnesium sphere include: the mass percentage of MgO is more than or equal to 70%, the mass percentage of CaO is not more than 4.5% and not less than 1.5%, and the proportion of the part with the granularity of 5 mm-50 mm is more than or equal to 90%.
According to the embodiment of the application, the magnesium balls have higher MgO content, which is more beneficial to fluxing, and the effect of thick slag can be realized by a smaller amount.
In some embodiments, the parameters of raw dolomite include: the mass percent of MgO is more than or equal to 18.5 percent, the mass percent of MgO plus CaO is more than or equal to 51 percent, and the proportion of the part with the granularity of 5 mm-30 mm is more than or equal to 90 percent.
In some embodiments, the splash slag adopts a nitrogen blowing mode, the pressure of nitrogen is controlled to be 1.10 MPa-1.35 MPa in the operation process, and the flow of nitrogen is 27000m 3 /h～30000m 3 /h。
According to the embodiment of the application, the pressure of the nitrogen is in the proper range, so that on one hand, the injected air flow can be ensured to have enough impact force to improve the slag splashing efficiency in the converter; on the other hand, the risk of erosion of the furnace mouth wall material caused by overlarge impact force of the injected air flow can be reduced. Therefore, the slag splashing efficiency in the converter, the operation rate of the converter and the feeding efficiency can be improved, and meanwhile, the damage to the wall material of the furnace mouth can be reduced, so that the service life of the furnace lining can be prolonged, and the maintenance cost of the converter can be reduced.
According to the embodiment of the application, the nitrogen flow of the oxygen lance is in the proper range, and the consumption of oxygen can be reduced on the premise that the airflow sprayed by the oxygen lance is allowed to have enough impact force. Therefore, the cost of slag splashing furnace protection can be reduced while the efficiency of slag splashing furnace protection is ensured.
In some embodiments, the flow of nitrogen is moved up and down during the slag splashing operation, and the flow of nitrogen is moved between 0cm and 100cm before slag is splashed out of the mouth of the converter to promote slag lifting, and the flow of nitrogen is moved between 20cm and 60cm after slag lifting.
According to the embodiment of the application, the nitrogen gas flows up and down in the slag splashing operation process, and particularly the oxygen lance can be used for purging, so that a nozzle of the oxygen lance can be used for purging between the bottom of the converter and the height 100cm away from the bottom of the converter. The nozzle of the oxygen lance is purged in the proper range, so that nitrogen flow sprayed by the oxygen lance can not only sputter slag to the furnace lining of the converter, but also can not erode the wall material of the furnace mouth. Therefore, the efficiency of slag splashing protection and the service life of a furnace lining are ensured.
In some embodiments, the slag is sputtered for a period of time ranging from 1.5 to 3.5 minutes and the slag is tapped for a period of time ranging from 0.5 to 1.5 minutes.
According to the embodiment of the application, the duration of the purging is within the shorter range, the purging can be allowed to be performed in the process of lifting the oxygen lance, and the residence time of the oxygen lance is shorter. This can improve the operating efficiency of the converter.
Examples
The present disclosure is more particularly described in the following examples that are intended as illustrations only, since various modifications and changes within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the examples below are by weight, and all reagents used in the examples are commercially available or were obtained synthetically according to conventional methods and can be used directly without further treatment, as well as the instruments used in the examples.
Example 1:
the temperature of molten steel in a converter is 1655 ℃ after blowing, and when slag splashing is carried out, the method comprises the following steps:
s1-1, adding 1.9 kg/ton of lime and 1.9 kg/ton of raw dolomite into a furnace when a gun is pressed at a converting end point, and shaking a furnace body after tapping, wherein the slag remaining amount of a converter is 60 kg/ton of steel;
s1-2, adding 1.1kg of raw dolomite per ton of steel, and then blowing nitrogen gas to splash slag.
Further, the pressure of nitrogen is controlled to be 1.25MPa in the slag splashing operation process, and the flow rate of the nitrogen is 27750m3/h.
Further, the lance position of the oxygen lance moves up and down in the slag splashing operation process, before granular slag jumps out of a furnace mouth, the lance position is shuttled back and forth between 0cm and 100cm to promote slag splashing, the time of the shuttle is 75 seconds, after slag splashing, the slag splashing lance position stays for 15 seconds at 20cm, stays for 15 seconds at 40cm, stays for 15 seconds at 60cm, and then descends to 20cm again, and the recycling is performed. And the final total slag splashing time is 165s, wherein the slag splashing time is 90s.
Example 2:
when the temperature of molten steel in a furnace is 1630 ℃ after blowing is finished, a 100t converter of a certain metallurgical enterprise is 5640-6888 in the furnace life, and slag splashing protection comprises the following steps:
s2-1, pouring out part of converter slag after converting, and shaking up the furnace body after pouring out the slag, wherein the slag remaining amount of the converter is 32 kg/ton of steel;
s2-2, adding 1.9 kg/ton of lime and 1.9 kg/ton of magnesium balls, and tapping thick slag;
s2-3, shaking the furnace body after tapping, and then blowing nitrogen gas to splash slag by a lower gun;
s2-4, adding lime 5.2 kg/ton of steel as a backing material when the slag splashing is finished and the gun is ready to be started.
Further, the pressure of nitrogen is controlled to be 1.20MPa and the flow rate of nitrogen is 27350m in the slag splashing operation process 3 /h。
Further, the lance position of the oxygen lance moves up and down in the slag splashing operation process, before granular slag jumps out of a furnace mouth, the lance position is shuttled back and forth between 0cm and 100cm to promote slag splashing, the time of the shuttle is 45s, after slag splashing, the slag splashing lance position stays for 20s at 20cm, stays for 15s at 40cm, stays for 20s at 60cm, and then descends to 20cm again, and the recycling is performed. And the final slag splashing total time is 155s, wherein the slag splashing time is 110s.
Comparative analysis of the lining data during the examples was performed using a laser thickness gauge and the data are shown in table 1.
Table 1 comparative analysis data
Remarks: the "-" sign indicates a furnace lining thickness increase.
As can be seen from Table 1, the thickness of the furnace lining is ensured after the slag splashing furnace protection method provided by the invention is adopted, and the guarantee is provided for stable and smooth production.
Examples the slag composition before and after addition of slag conditioning agents, data are shown in table 2.
As can be seen from the results of Table 2, the slag alkalinity was increased, the oxidizing property was decreased, and the dephosphorizing ability was improved after the lime and magnesium source were added. In addition, the MgO content of the slag is synchronously improved, the viscosity of the slag is increased, and the purposes of thick slag tapping and thick slag splashing protection can be realized.
While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (8)
1. A method for slag splashing protection, which is characterized by comprising the following steps:
acquiring the temperature of molten steel covered by slag in a converter;
when the temperature is higher than 1640 ℃, adding 1.8 kg/ton steel to 2.3 kg/ton steel and 1.8 kg/ton steel to 2.3 kg/ton steel of raw dolomite into the converter at the end point of converting to obtain first slag;
pouring out molten steel, and making the balance of the first slag in the converter be 55 kg/ton steel to 72 kg/ton steel;
adding 0.8 kg/ton steel to 1.2 kg/ton steel of raw dolomite into the rest of the first slag to obtain second slag;
sputtering the second slag onto a lining of the converter;
when the temperature is not higher than 1640 ℃, pouring out part of slag at the end of converting, so that the balance of slag is 25 kg/ton steel to 40 kg/ton steel;
adding 1.8 kg/ton steel to 2.3 kg/ton steel of lime and 1.8 kg/ton steel to 2.3 kg/ton steel of magnesium balls into the converter to obtain third slag;
and after pouring out the molten steel, sputtering the third slag onto the furnace lining of the converter.
2. The method of slag splashing protection as claimed in claim 1, wherein after the third slag is sputtered onto the lining of the converter, the method further comprises:
when the slag splashing is finished and the gun is ready to be started, 4.4 kg/ton of lime-5.6 kg/ton of steel is added to be used as a backing material.
3. A method of slag splashing protection as claimed in any one of claims 1 to 2, wherein the physicochemical properties of the lime include: the mass percentage of CaO is more than or equal to 90%, the activity degree is more than or equal to 360, the ignition loss is less than or equal to 5%, and the proportion of the part with the granularity of 10 mm-60 mm is at least 90%.
4. The slag splashing furnace protecting method according to claim 1 or 2, wherein the parameters of the magnesium balls comprise: the mass percentage of MgO is more than or equal to 70%, the mass percentage of CaO is not more than 4.5% and not less than 1.5%, and the proportion of the part with the granularity of 5 mm-50 mm is more than or equal to 90%.
5. The method for slag splashing protection as claimed in claim 1, wherein the parameters of the raw dolomite include: the mass percent of MgO is more than or equal to 18.5 percent, the mass percent of MgO plus CaO is more than or equal to 51 percent, and the proportion of the part with the granularity of 5 mm-30 mm is more than or equal to 90 percent.
6. The method for slag splashing protection according to any one of claims 1-2, wherein the slag splashing adopts a nitrogen blowing mode, the pressure of the nitrogen is controlled to be 1.10-1.35 MPa in the operation process, and the flow rate of the nitrogen is 27000m 3 /h～30000m 3 /h。
7. The method of slag splashing protection according to claim 6, wherein the flow of nitrogen gas is moved up and down during slag splashing operation, and the flow of nitrogen gas is moved between 0cm and 100cm before slag splashes out of the mouth of the converter to promote slag lifting, and the flow of nitrogen gas is moved between 20cm and 60cm after slag lifting.
8. The method for protecting slag as claimed in claim 7, wherein the sputtering time of slag is 1.5 min-3.5 min, and the slag lifting time is 0.5 min-1.5 min.
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