CN116377173A - Method for directly tapping molten iron through pre-desulfurization in high-speed rail steel smelting process - Google Patents
Method for directly tapping molten iron through pre-desulfurization in high-speed rail steel smelting process Download PDFInfo
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 208
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 104
- 238000000034 method Methods 0.000 title claims abstract description 72
- 238000010079 rubber tapping Methods 0.000 title claims abstract description 59
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 46
- 239000010959 steel Substances 0.000 title claims abstract description 46
- 238000003723 Smelting Methods 0.000 title claims abstract description 45
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 35
- 230000023556 desulfurization Effects 0.000 title claims abstract description 33
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 68
- 238000007664 blowing Methods 0.000 claims abstract description 66
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 60
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 60
- 239000004571 lime Substances 0.000 claims abstract description 60
- 238000010926 purge Methods 0.000 claims description 14
- 230000003111 delayed effect Effects 0.000 claims description 13
- 239000003054 catalyst Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 12
- 238000005272 metallurgy Methods 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 17
- 238000005259 measurement Methods 0.000 description 11
- 229910052717 sulfur Inorganic materials 0.000 description 6
- 239000011593 sulfur Substances 0.000 description 6
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 5
- 238000005070 sampling Methods 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 4
- 230000003009 desulfurizing effect Effects 0.000 description 4
- 238000007670 refining Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009851 ferrous metallurgy Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
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- G—PHYSICS
- G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
- G16C—COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
- G16C20/00—Chemoinformatics, i.e. ICT specially adapted for the handling of physicochemical or structural data of chemical particles, elements, compounds or mixtures
- G16C20/10—Analysis or design of chemical reactions, syntheses or processes
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- G—PHYSICS
- G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
- G16C—COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
- G16C20/00—Chemoinformatics, i.e. ICT specially adapted for the handling of physicochemical or structural data of chemical particles, elements, compounds or mixtures
- G16C20/20—Identification of molecular entities, parts thereof or of chemical compositions
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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
- Y02P10/20—Recycling
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- Bioinformatics & Cheminformatics (AREA)
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention belongs to the technical field of metallurgy, and relates to a method for directly tapping molten iron through pre-desulfurization in a high-speed rail steel smelting process, which is characterized in that after the molten iron desulfurization starts converting, according to an existing secondary model, the temperature of the molten iron is measured on line and the actual consumption proportion of magnesium powder and lime is calculated before converting is finished; according to the deviation condition of the actual consumption proportion of the molten iron temperature, the magnesium powder and the lime and the calculated value of the secondary model, the adding types and the adding amount of the magnesium powder and the lime are controlled, and then the hit of the S content of the molten iron end point is ensured by controlling the flow of the bottom blowing gas. The invention can produce iron at the end of desulfurization converting without blowing, the production smelting period is reduced by 3.5 minutes on average, and the production cost is reduced by 12.5 yuan/ton. Compared with the traditional molten iron pre-desulfurization process, the method effectively improves the molten iron pre-desulfurization production efficiency and reduces the production cost.
Description
Technical Field
The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a method for directly tapping molten iron through pre-desulfurization in a high-speed rail steel smelting process.
Background
As a support for railways, rails are an important foundation. Because of the safety problems involved in life, rail steels are the most demanding in terms of quality compared to other steels. At present, most high-quality steel in the market needs molten iron pretreatment when smelting, on one hand, the sulfur content in the finished product material can be controlled at an extremely low level, and on the other hand, the desulfurization pressure of external refining can be reduced after the molten iron pretreatment is desulfurized, so that the non-metallic inclusion in molten steel can be better removed by external refining. In the smelting process of high-quality steel, the molten iron pretreatment is taken as a basic treatment method, so that low-sulfur molten iron is provided for converter smelting, the desulfurization burden of the subsequent refining process is lightened, and the internal quality of molten steel is improved. Therefore, the pretreatment of molten iron is a necessary condition for smelting high-quality steel.
Because of the product specificity, the rail for the railway adopts an aluminum-free deoxidization technology in the smelting process, the refining is controlled by low-alkalinity slag, and the desulfurization capability is weak, so that the pretreatment process of molten iron before entering a converter is further required to control the sulfur content in the molten iron to a very low level, and the standard requirement of the high-speed rail can be met. However, in the conventional smelting process of high-speed rail steel, the molten iron pretreatment is carried out in a longer treatment process, so that the high-speed rail steel is subjected to great cost pressure. Whether a composite blowing method or a KR stirring method is adopted for desulfurization, after the desulfurizing agent reacts with molten iron, sampling is needed, the sample is sent to a laboratory for analysis, and after the inspection result is qualified, the sample can be directly discharged; if the test result is not qualified, the secondary blowing, sampling and analysis are needed, and then tapping is carried out. And (3) reporting from sampling to test results, wherein the time is 3-5min, and the time for re-spraying, sampling and analysis is 10-12min. The lengthy, equal sample and slag skimming links of the molten iron desulfurization period seriously affect the improvement of the production efficiency and the reduction of the cost.
The patent CN201711165245.X provides a method for controlling the sulfur content in the molten iron pre-desulfurization process, and the core idea is to realize low-cost molten iron pre-desulfurization by controlling the use of desulfurizing agents in different injection stages, but the aim of high-efficiency production is fulfilled by not realizing direct tapping at the end point.
Patent CN201510791844.7 provides a method for controlling the KR endpoint sulfur content. The method has the core ideas of establishing a standardized operation mode to replace a conventional empirical operation method and improve the overall desulfurization efficiency, but does not relate to optimization of the desulfurization process flow.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for directly tapping molten iron through pre-desulfurization in the high-speed rail steel smelting process, which realizes sample-free tapping through technological innovation, improves the pre-desulfurization efficiency of molten iron and reduces the production cost.
The technical scheme adopted by the invention is as follows: after the molten iron desulfurization starts converting, according to the existing secondary model, before converting is finished, measuring the temperature of the molten iron on line, and calculating the actual consumption proportion of magnesium powder and lime;
(1) If the actual consumption proportion of molten iron, magnesium powder and lime has deviation with the calculated value of the secondary model, namely the difference between the molten iron temperature and the target temperature is more than or equal to 10 degrees, the deviation between the actual consumption proportion of magnesium powder and lime and the calculated value of the secondary model is more than or equal to 5 percent, adding less than or equal to 0.8kg/t of magnesium powder, and taking the blowing time calculated by the secondary model after 3 minutes as a blowing end point, and simultaneously, in the blowing process, blowing gas is in accordance with 200+/-10 Nm 3 Controlling the flow rate of the furnace until converting is finished, and then tapping; the operation is under the most adverse condition that the actual consumption proportion of the magnesium powder and the lime has deviation in the temperature calculated by the secondary modelThe strong desulfurizing agent magnesium powder is added to create conditions for continuous desulfurization of molten iron, and simultaneously, continuous nitrogen blowing is used at the end point to create conditions for continuous desulfurization, and then the bottom blowing control of the maximum flow is used for assisting in realizing strong stirring of a molten pool, so that hit of the S content of the end point of the molten iron is realized to the maximum extent.
(2) If the molten iron temperature hits, the actual consumption proportion of magnesium powder and lime deviates from the calculated value of the secondary model, namely the difference between the molten iron temperature and the target temperature is less than 10 degrees, the actual consumption proportion of magnesium powder and lime deviates from the calculated value of the secondary model by more than or equal to 5 percent, the magnesium powder is added by less than or equal to 0.5kg/t, the lime is added by less than or equal to 1.5kg/t, the blowing time calculated by the secondary model is delayed by 2 minutes and is taken as the blowing end point, and meanwhile, in the blowing process, the blowing gas is in the range of less than or equal to 180Nm 3 Controlling the flow rate of the furnace until converting is finished, and then tapping; under the unfavorable condition that the consumption proportion of magnesium powder and lime deviates from the actual consumption proportion, the method creates conditions for continuous desulfurization of molten iron by adding the magnesium powder and the lime in a certain proportion, and realizes strong stirring of a molten pool by a high-flow bottom blowing control mode, so that the S content of the molten iron is hit.
(3) If the calculated value of the secondary model deviates from the molten iron temperature, the actual consumption proportion of the magnesium powder and the lime hits, namely the difference between the molten iron temperature and the target temperature is more than or equal to 10 degrees, the deviation between the actual consumption proportion of the magnesium powder and the lime and the calculated value of the secondary model is less than 5 percent,
when the temperature of molten iron and the target temperature are positively deviated, lime is added to be less than or equal to 2.5kg/t, and the converting time calculated by the secondary model is delayed by 2.5min and is used as a converting end point, and in the converting process, the blowing gas is added according to the speed of less than or equal to 180Nm 3 Controlling the flow rate of the furnace until converting is finished, and then tapping;
when the temperature of molten iron and the target temperature are in negative deviation, adding magnesium powder less than or equal to 0.5kg/t, and taking the converting time calculated by the secondary model after 1.5min as a converting end point, wherein in the converting process, the blowing gas is in a range of less than or equal to 180Nm 3 Controlling the flow rate of the furnace until converting is finished, and then tapping;
on the premise that the calculated temperature of the second-level model has positive deviation from the actual temperature, lime is added to sufficiently cool so as to improve the activity coefficient of MnS and promote the hit of the end point component; on the premise that the calculated temperature of the second-level model and the actual temperature are negative deviations, a proper amount of magnesium powder is added to continuously improve the desulfurization efficiency of molten steel and ensure the hit of the sulfur content of the end point; the two conditions are both assisted by a bottom blowing control mode with a certain flow to realize the stirring of molten iron, and a foundation is laid for the hit of the end point component.
The invention measures the temperature of the molten iron on line 3min before the blowing is finished.
In the invention (1), 0.6-0.8 kg/t of magnesium powder is added.
In the invention (2), 0.2-0.5 kg/t of magnesium powder and 0.8-1.5 kg/t of lime are added.
In the step (3), when the temperature of molten iron and the target temperature are in positive deviation, lime is added by 1.5-2.5 kg/t; when the temperature of molten iron and the target temperature are in negative deviation, adding 0.3-0.5 kg/t of magnesium powder.
In the above (2) and (3), the purge gas is 150 to 180Nm 3 And controlling the flow rate of the catalyst/h until the blowing is finished.
According to the invention, if the actual consumption proportion of molten iron temperature, magnesium powder and lime is hit, namely the difference between the molten iron temperature and the target temperature is less than 10 degrees, the deviation between the actual consumption proportion of magnesium powder and lime and the calculated value of the secondary model is less than 5 percent, converting and tapping are carried out according to the secondary model.
The beneficial effects of adopting above-mentioned technical scheme to produce lie in: the traditional high-speed rail steel smelting iron-making water pretreatment process adopts the steps of blowing a desulfurizing agent, sampling and analyzing, and then selecting to blow or discharge iron again according to the result, so that the improvement of the production efficiency is affected. Under the steelmaking process condition of the secondary calculation model, the process control is carried out according to the measuring condition of the sublance, the iron can be discharged after the desulfuration blowing is finished, the supplementary blowing is not needed, the production smelting period is reduced by 3.5 minutes on average, the production cost is reduced by 12.5 yuan/ton, the desulfuration high-efficiency low-cost smelting is realized, the method can be applied to the steelmaking process in a large scale, and the operation is simple and convenient, and the effect is stable. Compared with the traditional molten iron pre-desulfurization process, the method can effectively improve the molten iron pre-desulfurization production efficiency and reduce the production cost.
Detailed Description
The present invention will be described in further detail with reference to examples.
Example 1
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of the molten iron is 1350 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of the magnesium powder to the lime is 1:3.2. The target temperature value calculated by the secondary model is 1320 ℃, and the consumption ratio of magnesium powder to lime is 1:3.5. For this case, magnesium powder was added at 0.6kg/t, and the converting time calculated by the secondary model was delayed by 3min as the converting end point, while the flow rate of the purge gas during converting was 210Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.002 percent, which is less than or equal to 0.005 percent of the standard requirement, meets the quality requirement of high-speed rail steel, and realizes the non-uniform tapping. The smelting time is reduced by 3.2 minutes compared with the normal heat.
Example 2
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of molten iron is 1320 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of magnesium powder to lime is 1:3.5. The target temperature value calculated by the second-level model is 1330 ℃, and the consumption ratio of magnesium powder to lime is 1:3.8. For this case, magnesium powder was added at 0.8kg/t, and the blowing time calculated by the secondary model was delayed by 3min as the end point of blowing, while the flow rate of the purge gas during the blowing was 190Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.001 percent, which is less than or equal to 0.005 percent of the standard requirement, meets the quality requirement of high-speed rail steel, and realizes the non-uniform tapping. The smelting time is reduced by 3.8 minutes compared with the normal heat.
Example 3
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of molten iron is 1310 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of magnesium powder to lime is 1:3.2. The target temperature value calculated by the second-level model is 1305 ℃, and the consumption ratio of magnesium powder to lime is 1:3.5. For this case, adding magnesium powder 0.2kg/t and lime 0.8kg/t, and delaying the converting time calculated by the secondary model for 2min as converting end point, wherein during converting, the flow rate of purge gas is 150Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.002 percent, which is less than or equal to 0.004 percent of the standard requirement, thereby meeting the quality requirement of high-speed rail steel and realizing the non-uniform tapping. The smelting time is reduced by 2.9 minutes compared with the normal heat.
Example 4
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of molten iron is 1320 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of magnesium powder to lime is 1:3.5. The target temperature value calculated by the secondary model is 1318 ℃, and the consumption ratio of magnesium powder to lime is 1:3.8. For this case, adding magnesium powder 0.5kg/t and lime 1.5kg/t, and delaying the converting time calculated by the secondary model for 2min as converting end point, wherein during converting, the flow of purge gas is 180Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.004%, which is lower than the standard requirement by not more than 0.005%, thereby meeting the quality requirement of high-speed rail steel and realizing unequal tapping. The smelting time is reduced by 3.1 minutes compared with the normal heat.
Example 5
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
On-line measuring molten iron temperature at 1310 deg.c for 3min before the first converting processThe actual ash consumption ratio was 1:3.4. The target temperature value calculated by the second-level model is 1340 ℃, and the consumption ratio of magnesium powder to lime is 1:3.5. For this case, 1.5kg/t lime was added and the converting time calculated by the secondary model was delayed by 2.5min as the converting end point, while the flow rate of the purge gas was 150Nm during the converting 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.003 percent, which is lower than the standard requirement by not more than 0.005 percent, thereby meeting the quality requirement of high-speed rail steel and realizing the non-uniform tapping. The smelting time is reduced by 3.5 minutes compared with the normal heat.
Example 6
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of molten iron is 1305 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of magnesium powder to lime is 1:3.2. The target temperature value calculated by the secondary model is 1320 ℃, and the consumption ratio of magnesium powder to lime is 1:3.3. For this case, lime addition of 2.5kg/t was adopted, and the converting time calculated by the secondary model was delayed by 2.5min as the converting end point, while the flow rate of the purge gas during converting was 180Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.003 percent, which is lower than the standard requirement by not more than 0.005 percent, thereby meeting the quality requirement of high-speed rail steel and realizing the non-uniform tapping. The smelting time is reduced by 3.5 minutes compared with the normal heat.
Example 7
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of the molten iron is 1350 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of the magnesium powder to the lime is 1:3.7. The target temperature value calculated by the secondary model is 1320 ℃, and the consumption ratio of magnesium powder to lime is 1:3.8. For this case, 0.3kg/t of magnesium powder is added, and the converting time calculated by the secondary model is delayed by 1.5min as converting end point, whileIn the blowing process, the flow rate of the purge gas was 150Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.002 percent, which is less than or equal to 0.005 percent of the standard requirement, meets the quality requirement of high-speed rail steel, and realizes the non-uniform tapping. The smelting time is reduced by 3.2 minutes compared with the normal heat.
Example 8
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of the molten iron is 1360 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of magnesium powder to lime is 1:3.8. The target temperature value calculated by the secondary model is 1315 ℃, and the consumption ratio of magnesium powder to lime is 1:3.9. For this case, magnesium powder was added at 0.5kg/t, and the converting time calculated by the secondary model was delayed by 1.5min as the converting end point, while the flow rate of the purge gas was 180Nm during the converting 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.001 percent, which is less than or equal to 0.005 percent of the standard requirement, meets the quality requirement of high-speed rail steel, and realizes the non-uniform tapping. The smelting time is reduced by 3.3 minutes compared with the normal heat.
Example 9
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of molten iron is 1318 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of magnesium powder to lime is 1:3.5. The target temperature value calculated by the secondary model is 1341 ℃, and the consumption ratio of magnesium powder to lime is 1:3.7. For this case, magnesium powder was added at 0.7kg/t, and the blowing time calculated by the secondary model was delayed by 3min as the end point of the blowing, while the flow rate of the purge gas during the blowing was 200Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.003 percent, which is lower than the standard requirement by not more than 0.005 percent, thereby meeting the quality requirement of high-speed rail steel and realizing the non-uniform tapping.The smelting time is reduced by 3.6 minutes compared with the normal heat.
Example 10
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of molten iron is 1313 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of magnesium powder to lime is 1:3.3. The target temperature value calculated by the secondary model is 1304 ℃, and the consumption ratio of magnesium powder to lime is 1:3.5. For this case, adding magnesium powder 0.4kg/t and lime 1.0kg/t, and delaying the converting time calculated by the secondary model for 2min as converting end point, while in converting process, the flow of purge gas is 166Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.001 percent, which is less than or equal to 0.005 percent of the standard requirement, meets the quality requirement of high-speed rail steel, and realizes the non-uniform tapping. The smelting time is reduced by 2.8 minutes compared with the normal heat.
Example 11
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of molten iron is 1306 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of magnesium powder to lime is 1:3.4. The target temperature value calculated by the secondary model is 1318 ℃, and the consumption ratio of magnesium powder to lime is 1:3.5. For this case, lime addition of 2.2kg/t was adopted, and the converting time calculated by the secondary model was delayed by 2.5min as the converting end point, while the flow rate of the purge gas during converting was 175Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.004%, which is lower than the standard requirement by not more than 0.005%, thereby meeting the quality requirement of high-speed rail steel and realizing unequal tapping. The smelting time is reduced by 3.3 minutes compared with the normal heat.
Example 12
In the embodiment, the ladle with the nominal capacity of 120 tons is taken as an example, and in the process of smelting high-speed rail steel, blowing and control are performed according to the calculated amount of the secondary model in the pretreatment of molten iron.
The temperature of the molten iron is 1344 ℃ in an online measurement mode 3min before the first blowing is finished, and the actual consumption ratio of magnesium powder to lime is 1:3.6. The target temperature value calculated by the secondary model is 1321 ℃, and the consumption ratio of magnesium powder to lime is 1:3.7. For this case, 0.4kg/t of magnesium powder was added, and the converting time calculated by the secondary model was delayed by 1.5min as the converting end point, while the flow rate of the purge gas during converting was 160Nm 3 And/h, until converting is finished, and then tapping. After the tapping, the S content of the molten iron end point is 0.002 percent, which is less than or equal to 0.005 percent of the standard requirement, meets the quality requirement of high-speed rail steel, and realizes the non-uniform tapping. The smelting time is reduced by 3.2 minutes compared with the normal heat.
Claims (6)
1. A method for directly tapping molten iron through pre-desulfurization in a high-speed rail steel smelting process is characterized in that after molten iron desulfurization starts converting, the temperature of the molten iron is measured on line and the actual consumption proportion of magnesium powder and lime is calculated according to an existing secondary model before converting is finished;
(1) If the actual consumption proportion of molten iron, magnesium powder and lime has deviation with the calculated value of the secondary model, namely the difference between the molten iron temperature and the target temperature is more than or equal to 10 degrees, the deviation between the actual consumption proportion of magnesium powder and lime and the calculated value of the secondary model is more than or equal to 5 percent, adding less than or equal to 0.8kg/t of magnesium powder, and taking the blowing time calculated by the secondary model after 3 minutes as a blowing end point, and simultaneously, in the blowing process, blowing gas is in accordance with 200+/-10 Nm 3 Controlling the maximum flow rate of the process until converting is finished, and then tapping;
(2) If the molten iron temperature hits, the actual consumption proportion of magnesium powder and lime deviates from the calculated value of the secondary model, namely the difference between the molten iron temperature and the target temperature is less than 10 degrees, the actual consumption proportion of magnesium powder and lime deviates from the calculated value of the secondary model by more than or equal to 5 percent, the magnesium powder is added by less than or equal to 0.5kg/t, the lime is added by less than or equal to 1.5kg/t, the blowing time calculated by the secondary model is delayed by 2 minutes and is taken as the blowing end point, and meanwhile, in the blowing process, the blowing gas is in the range of less than or equal to 180Nm 3 Controlling the flow rate of the furnace until converting is finished, and then tapping;
(3) If the calculated value of the secondary model deviates from the molten iron temperature, the actual consumption proportion of the magnesium powder and the lime hits, namely the difference between the molten iron temperature and the target temperature is more than or equal to 10 degrees, the deviation between the actual consumption proportion of the magnesium powder and the lime and the calculated value of the secondary model is less than 5 percent,
when the target temperature-molten iron temperature is the positive deviation, lime is added to be less than or equal to 2.5kg/t, and the converting time calculated by the secondary model is delayed by 2.5min and is used as the converting end point, and in the converting process, the blowing gas is added according to the speed of less than or equal to 180Nm 3 Controlling the flow rate of the furnace until converting is finished, and then tapping;
when the target temperature-molten iron temperature is negative deviation, adding magnesium powder less than or equal to 0.5kg/t, and taking the converting time calculated by the secondary model after 1.5min as a converting end point, wherein in the converting process, the blowing gas is in a range of less than or equal to 180Nm 3 And controlling the flow rate/h until blowing is finished, and then tapping.
2. The method for directly tapping molten iron through pre-desulfurization in the high-speed rail steel smelting process according to claim 1, wherein the method comprises the following steps of: the temperature of the molten iron was measured on line 3min before the end of blowing.
3. The method for directly tapping molten iron through pre-desulfurization in the high-speed rail steel smelting process according to claim 2, wherein the method comprises the following steps of: in the step (1), 0.6-0.8 kg/t of magnesium powder is added.
4. The method for directly tapping molten iron through pre-desulfurization in the high-speed rail steel smelting process according to claim 3, wherein the method comprises the following steps of: and (2) adding 0.2-0.5 kg/t of magnesium powder and 0.8-1.5 kg/t of lime.
5. The method for directly tapping molten iron through pre-desulfurization in the high-speed rail steel smelting process according to claim 4, wherein the method comprises the following steps of: in the step (3), when the temperature of molten iron and the target temperature are positively deviated, lime is added by 1.5-2.5 kg/t; when the temperature of molten iron and the target temperature are in negative deviation, adding 0.3-0.5 kg/t of magnesium powder.
6. The method for directly tapping molten iron through pre-desulfurization in a high-speed rail steel smelting process according to any one of claims 1-5, wherein the method comprises the following steps: in the above (2) and (3), the purge gas is 150 to 180Nm 3 And controlling the flow rate of the catalyst/h until the blowing is finished.
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| CN202310298109.7A CN116377173A (en) | 2023-03-24 | 2023-03-24 | Method for directly tapping molten iron through pre-desulfurization in high-speed rail steel smelting process |
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