CN108148946B - LF furnace refining process - Google Patents
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- CN108148946B CN108148946B CN201810013101.0A CN201810013101A CN108148946B CN 108148946 B CN108148946 B CN 108148946B CN 201810013101 A CN201810013101 A CN 201810013101A CN 108148946 B CN108148946 B CN 108148946B
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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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- 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
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
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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
- C21C7/06—Deoxidising, e.g. killing
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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
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- Y02P10/20—Recycling
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Abstract
The invention discloses an LF furnace refining process, relates to the technical field of steel smelting, and solves the problem that carburetion is difficult to control effectively while deep desulfurization is performed. According to the invention, the argon flow is dynamically controlled in stages when the lime and the calcium carbide are heated and added, so that sufficient argon blowing stirring work is ensured to ensure the desulfurization effect, and meanwhile, the steel and slag are prevented from violently stirring due to overlarge argon flow in the heating process, so that the steel and slag are in contact reaction with the graphite electrode to cause direct or indirect recarburization, and not only is the deep desulfurization completed, but also the recarburization is effectively controlled; the invention completes the task of deep desulfurization of molten steel by using several conventional materials such as lime, calcium carbide, iron calcium wire and the like, has less medicament investment and saves cost.
Description
Technical Field
the invention relates to the technical field of steel smelting, in particular to a refining process of an LF (ladle furnace).
background
with the increasing requirements of users on the quality of steel products, a ladle refining furnace (ladlefurace abbreviated as LF furnace) is rapidly developed as a means for improving the cleanliness of molten steel and improving the quality of steel products, and is now an indispensable process in the short process of modern steel production. Besides adopting mature secondary refining technologies such as reducing atmosphere submerged arc heating, vacuum degassing, air brick argon blowing stirring and the like, the LF refining furnace also introduces a synthetic slag refining technology to achieve the purposes of desulfurization, deoxidation and even denitrification through a reasonable slagging process, thereby effectively absorbing impurities in steel, controlling the form of the impurities, and in addition, the LF refining furnace can also utilize foamed slag formed by steelmaking to submerge electric arcs, improve the heat efficiency and reduce the corrosion of refractory materials.
at present, the deep desulfurization technology mainly comprises the deep desulfurization of molten iron, the control of sulfur increase of a primary smelting furnace, the deep desulfurization of molten steel, the prevention of resulfurization and the like, and the deep desulfurization of the molten steel mainly adopts the LF and RH (vacuum cycle degassing refining) combined technology. The LF furnace has to rely on good dynamic conditions for realizing the ultralow sulfur, namely, stronger bottom blowing argon stirring, but the bottom blowing argon stirring can directly cause the obvious fluctuation of the liquid level of molten steel, and the liquid level fluctuation can cause the contact between an electrode and the molten steel to generate contact recarburization; in addition, the slag is contacted with the electrode by stronger bottom blowing argon stirring, and indirect recarburization of the molten steel is also caused. The recarburization brought by the electrode mainly has two forms, one is that molten steel or furnace slag scours the surface of the electrode by violent stirring, so that carbon powder on the surface layer part of the electrode falls off and is alloyed; secondly, the electrode is in contact with the slag through violent stirring, and the electrode entering the slag and oxides in the slag are generated during heating, such as: FeO, MnO, V2O5and the like, the following reaction is carried out: c + FeO → CO + Fe, C + MnO → CO + Mn, 5C + V2O5→ 5CO + 2V. As a result, the slag is unstableThe oxide is reduced, the reducibility and the desulfurization effect of the slag are improved, and simultaneously, the recarburization is further generated in the molten steel. Therefore, when the low-carbon and ultra-low-sulfur steel is actually produced, the carbon content is often too high due to operability factors such as improper argon blowing control at the bottom of the LF furnace, so that the RH furnace is forced to adopt an oxygen blowing and decarburization mode for component saving, and the quality and the production efficiency of molten steel are adversely affected.
at present, some researches on LF furnace deep desulfurization refining process are available at home and abroad, such as: the Chinese patent application with the publication number of CN102002554A and the publication date of 2011, 4 and 6, adopts a powder injection metallurgy mode for desulfurization, achieves a better desulfurization effect, but the sulfur content at the treatment end point is unstable, and the powder injection metallurgy increases the equipment investment; japanese patent application laid-open No. JP6145764A, published as 5/27/1994, mainly focuses on the study of refining slag systems and recycling of refining slag. Therefore, how to realize ultra-deep desulfurization and effectively control recarburization of the LF furnace is a problem to be solved at present.
disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide an LF (ladle furnace) refining process, which solves the problem that the recarburization is difficult to effectively control while the deep desulfurization is carried out by optimizing the whole-course argon blowing and supplying of the LF, dynamically controlling the argon flow in stages and adjusting slag in batches, and has the advantages of not only completing the deep desulfurization, but also effectively controlling the recarburization.
in order to achieve the first purpose, the invention provides the following technical scheme:
An LF furnace refining process comprises the following steps:
firstly, adding qualified molten steel blown by a converter into an LF furnace, controlling the temperature of the molten steel to be 1520-1540 ℃, controlling the components of the molten steel to be 0.37-0.42 percent of C, 0.10-0.17 percent of Si, 0.5-0.6 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 30ppm of T [ O ], and blowing argon gas at the bottom of the LF furnace during tapping;
Step two, transmitting electricity for heating, wherein the current is 25000-35000A, the heating and slagging time is 10-13min, measuring the temperature and sampling;
regulating the current to 30000-35000A, adding lime in 2-3 batches, wherein the adding amount of lime is 500-530kg, the flow of argon gas is regulated to 50-100L/min, and the pressure of the argon gas is 0.3-0.4 MPa;
deoxidizing the slag surface by adopting calcium carbide, adding the calcium carbide in batches for slag adjustment, wherein the total amount of the added calcium carbide is 1-1.5kg per ton of steel;
Step five, sampling and analyzing, adjusting according to target components, and improving the flow of argon after adjusting the components;
step six, soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 15-18min, the liquid level condition of the molten steel is observed in the soft blowing process, and the molten steel is prevented from being exposed;
And seventhly, adding ferrotitanium after the molten steel temperature is more than or equal to 1570 ℃ and the slag turns white, feeding an iron-calcium wire at a speed of 250 m/s and closing argon after the components and the temperature before leaving the station meet the process requirements, and finishing the steel making of the LF furnace.
More preferably, in the first step, the flow rate of the argon gas is 100-150L/min, and the pressure of the argon gas is 0.3-0.4 MPa.
further preferably, in the slagging process in the second step, the flow rate of argon is 250-350L/min, and the pressure of argon is 0.3-0.4 MPa.
More preferably, the third step specifically includes: adjusting the current to 30000-35000A, adding lime in 2-3 batches, wherein the adding amount of the lime is 500-530kg, the flow of argon is adjusted to 50-100L/min, the pressure of the argon is 0.3-0.4MPa, adding fluorite according to the fluidity of the slag, the amount of the slag is adjusted to 10-12 kg/ton steel, the alkalinity is controlled to 2.0-3.0, the white slag is kept for more than 15 minutes, and FeO + MnO is less than 1.0%.
more preferably, the fourth step specifically includes: and deoxidizing the slag surface by using calcium carbide, adding the calcium carbide in 5 batches for slag regulation, wherein 1/5 of the total amount of the calcium carbide is added each time, the time interval of adding the calcium carbide in each batch is 30s, and the total amount of the added calcium carbide is 1-1.5 kg/ton of steel.
More preferably, in the fifth step, the flow rate of the argon gas is 400 to 500L/min.
more preferably, the flow rate of argon gas in the soft blowing in the sixth step is 50 to 60L/min.
more preferably, in the seventh step, the titanium content of the ferrotitanium is 28-30%, and the recovery rate is 60-70%.
According to the invention, the flow of argon is dynamically controlled in stages when the lime and the calcium carbide are heated and added, so that sufficient argon blowing stirring work is ensured to ensure the desulfurization effect, and meanwhile, the steel and slag are prevented from violently stirring due to overlarge flow of argon in the heating process, and the steel and slag are in contact reaction with the graphite electrode to cause direct or indirect recarburization. Thus, in the whole refining process, the deep desulfurization is finished and the recarburization is effectively controlled. The method has the advantages that the desulfurization rate is over 93 percent, the recarburization is controlled to be below 45ppm, and steel products with the sulfur content below 6ppm can be stably produced. The invention completes the task of deep desulfurization of molten steel by using several conventional materials such as lime, calcium carbide, iron calcium wire and the like, has less medicament investment and saves cost. According to the invention, the flow of the argon is dynamically controlled in stages, so that the consumption of the argon per ton of steel is reduced, and the cost is saved.
In summary, compared with the prior art, the invention has the following beneficial effects:
(1) The flow of argon is dynamically controlled in stages when lime and calcium carbide are heated and added, so that sufficient argon blowing stirring power is ensured to ensure the desulfurization effect, and meanwhile, the steel and slag are prevented from violently stirring due to overlarge flow of argon in the heating process, so that the steel and slag are in contact reaction with a graphite electrode to cause direct or indirect recarburization, and the deep desulfurization is completed and the recarburization is effectively controlled;
(2) the invention completes the task of deep desulfurization of molten steel by only using a plurality of conventional materials such as lime, calcium carbide, iron calcium wires and the like, has less medicament investment and saves the cost;
(3) according to the invention, the flow of the argon is dynamically controlled in stages, so that the consumption of the argon per ton of steel is reduced, and the cost is saved.
drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
the invention is described in detail below with reference to the figures and examples.
example 1: as shown in fig. 1, an LF furnace refining process includes the following steps: the initial carbon and sulfur content of the incoming molten steel of the LF furnace is C: 0.04%, S: 0.009%;
Firstly, adding qualified molten steel blown by a converter into an LF furnace, controlling the temperature of the molten steel at 1520 ℃, controlling the components of the molten steel to be 0.37-0.42 percent of C, 0.10-0.17 percent of Si, 0.5-0.6 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 30ppm of T [ O ], blowing argon at the bottom of the LF furnace during tapping, wherein the flow of the argon is 100L/min, and the pressure of the argon is 0.3 MPa;
Step two, transmitting electricity for heating, wherein the current is 25000A, the heating and slagging time is 10min, the argon flow is 250L/min and the argon pressure is 0.3MPa in the slagging process, measuring the temperature and sampling;
Step three, adjusting the current to 30000A, adding lime in 2-3 batches, wherein the adding amount of the lime is 500kg, the flow rate of argon is adjusted to 50L/min, the pressure of the argon is 0.3MPa, adding fluorite according to the fluidity of slag, adjusting the slag amount of the slag to 10 kg/ton of steel, controlling the alkalinity to be 2.0, keeping the white slag for more than 15 minutes, and keeping FeO + MnO less than 1.0%;
fourthly, deoxidizing the slag surface by adopting calcium carbide, adding the calcium carbide in 5 batches for slag adjustment, adding 1/5 of the total amount of the calcium carbide each time, wherein the time interval of adding the calcium carbide in each batch is 30s, and the total amount of the added calcium carbide is 1kg per ton of steel;
Step five, sampling and analyzing, adjusting according to target components, and improving the argon flow after adjusting the components, wherein the argon flow is 400L/min;
Step six, soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 15min, the flow of argon during soft blowing is 50L/min, the liquid level condition of the molten steel is observed during the soft blowing process, and the molten steel is prevented from being exposed;
and seventhly, adding ferrotitanium after the temperature of the molten steel is more than or equal to 1570 ℃ and the slag turns white, wherein the titanium content of the ferrotitanium is 28 percent, the recovery rate is 60 percent, feeding an iron-calcium wire at the speed of 250m and 3-5m/s after the components and the temperature before leaving the station meet the process requirements, and closing argon to finish the steel making of the LF furnace.
example 2: an LF furnace refining process comprises the following steps: the initial carbon and sulfur content of the incoming molten steel of the LF furnace is C: 0.041%, S: 0.0095%;
Step one, adding qualified molten steel blown by a converter into an LF furnace, controlling the temperature of the molten steel at 1530 ℃, controlling the components of the molten steel to be 0.37-0.42% of C, 0.10-0.17% of Si, 0.5-0.6% of Mn0, less than or equal to 0.025% of P, less than or equal to 30ppm of T [ O ], blowing argon at the bottom of the LF furnace during tapping, wherein the flow of the argon is 125L/min, and the pressure of the argon is 0.35 MPa;
step two, transmitting electricity for heating, wherein the current is 25000A, the heating and slagging time is 10min, the argon flow is 250L/min and the argon pressure is 0.3MPa in the slagging process, measuring the temperature and sampling;
step three, adjusting the current to 30000A, adding lime in 2-3 batches, wherein the adding amount of the lime is 500kg, the flow rate of argon is adjusted to 50L/min, the pressure of the argon is 0.3MPa, adding fluorite according to the fluidity of slag, adjusting the slag amount of the slag to 10 kg/ton of steel, controlling the alkalinity to be 2.0, keeping the white slag for more than 15 minutes, and keeping FeO + MnO less than 1.0%;
fourthly, deoxidizing the slag surface by adopting calcium carbide, adding the calcium carbide in 5 batches for slag adjustment, adding 1/5 of the total amount of the calcium carbide each time, wherein the time interval of adding the calcium carbide in each batch is 30s, and the total amount of the added calcium carbide is 1kg per ton of steel;
Step five, sampling and analyzing, adjusting according to target components, and improving the argon flow after adjusting the components, wherein the argon flow is 400L/min;
Step six, soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 15min, the flow of argon during soft blowing is 50L/min, the liquid level condition of the molten steel is observed during the soft blowing process, and the molten steel is prevented from being exposed;
and seventhly, adding ferrotitanium after the temperature of the molten steel is more than or equal to 1570 ℃ and the slag turns white, wherein the titanium content of the ferrotitanium is 28 percent, the recovery rate is 60 percent, feeding an iron-calcium wire at the speed of 250m and 3-5m/s after the components and the temperature before leaving the station meet the process requirements, and closing argon to finish the steel making of the LF furnace.
example 3: an LF furnace refining process comprises the following steps: the initial carbon and sulfur content of the incoming molten steel of the LF furnace is C: 0.04%, S: 0.0088%;
Step one, adding qualified molten steel blown by a converter into an LF furnace, controlling the temperature of the molten steel at 1540 ℃, controlling the components of the molten steel to be 0.37-0.42% of C, 0.10-0.17% of Si, 0.5-0.6% of Mn, less than or equal to 0.025% of P, less than or equal to 30ppm of T [ O ], blowing argon at the bottom of the LF furnace during tapping, wherein the flow of the argon is 150L/min, and the pressure of the argon is 0.4 MPa;
Step two, transmitting electricity for heating, wherein the current is 25000A, the heating and slagging time is 10min, the argon flow is 250L/min and the argon pressure is 0.3MPa in the slagging process, measuring the temperature and sampling;
step three, adjusting the current to 30000A, adding lime in 2-3 batches, wherein the adding amount of the lime is 500kg, the flow rate of argon is adjusted to 50L/min, the pressure of the argon is 0.3MPa, adding fluorite according to the fluidity of slag, adjusting the slag amount of the slag to 10 kg/ton of steel, controlling the alkalinity to be 2.0, keeping the white slag for more than 15 minutes, and keeping FeO + MnO less than 1.0%;
fourthly, deoxidizing the slag surface by adopting calcium carbide, adding the calcium carbide in 5 batches for slag adjustment, adding 1/5 of the total amount of the calcium carbide each time, wherein the time interval of adding the calcium carbide in each batch is 30s, and the total amount of the added calcium carbide is 1kg per ton of steel;
Step five, sampling and analyzing, adjusting according to target components, and improving the argon flow after adjusting the components, wherein the argon flow is 400L/min;
Step six, soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 15min, the flow of argon during soft blowing is 50L/min, the liquid level condition of the molten steel is observed during the soft blowing process, and the molten steel is prevented from being exposed;
and seventhly, adding ferrotitanium after the temperature of the molten steel is more than or equal to 1570 ℃ and the slag turns white, wherein the titanium content of the ferrotitanium is 28 percent, the recovery rate is 60 percent, feeding an iron-calcium wire at the speed of 250m and 3-5m/s after the components and the temperature before leaving the station meet the process requirements, and closing argon to finish the steel making of the LF furnace.
example 4: an LF furnace refining process comprises the following steps: the initial carbon and sulfur content of the incoming molten steel of the LF furnace is C: 0.039%, S: 0.0089%;
firstly, adding qualified molten steel blown by a converter into an LF furnace, controlling the temperature of the molten steel at 1520 ℃, controlling the components of the molten steel to be 0.37-0.42 percent of C, 0.10-0.17 percent of Si, 0.5-0.6 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 30ppm of T [ O ], blowing argon at the bottom of the LF furnace during tapping, wherein the flow of the argon is 100L/min, and the pressure of the argon is 0.3 MPa;
step two, transmitting electricity for heating, wherein the current is 30000A, the heating and slagging time is 12min, the argon flow is 300L/min and the argon pressure is 0.35MPa in the slagging process, measuring the temperature and sampling;
step three, adjusting the current to 30000A, adding lime in 2-3 batches, wherein the adding amount of the lime is 500kg, the flow rate of argon is adjusted to 50L/min, the pressure of the argon is 0.3MPa, adding fluorite according to the fluidity of slag, adjusting the slag amount of the slag to 10 kg/ton of steel, controlling the alkalinity to be 2.0, keeping the white slag for more than 15 minutes, and keeping FeO + MnO less than 1.0%;
Fourthly, deoxidizing the slag surface by adopting calcium carbide, adding the calcium carbide in 5 batches for slag adjustment, adding 1/5 of the total amount of the calcium carbide each time, wherein the time interval of adding the calcium carbide in each batch is 30s, and the total amount of the added calcium carbide is 1kg per ton of steel;
step five, sampling and analyzing, adjusting according to target components, and improving the argon flow after adjusting the components, wherein the argon flow is 400L/min;
Step six, soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 15min, the flow of argon during soft blowing is 50L/min, the liquid level condition of the molten steel is observed during the soft blowing process, and the molten steel is prevented from being exposed;
and seventhly, adding ferrotitanium after the temperature of the molten steel is more than or equal to 1570 ℃ and the slag turns white, wherein the titanium content of the ferrotitanium is 28 percent, the recovery rate is 60 percent, feeding an iron-calcium wire at the speed of 250m and 3-5m/s after the components and the temperature before leaving the station meet the process requirements, and closing argon to finish the steel making of the LF furnace.
example 5: an LF furnace refining process comprises the following steps: the initial carbon and sulfur content of the incoming molten steel of the LF furnace is C: 0.042%, S: 0.0094%;
firstly, adding qualified molten steel blown by a converter into an LF furnace, controlling the temperature of the molten steel at 1520 ℃, controlling the components of the molten steel to be 0.37-0.42 percent of C, 0.10-0.17 percent of Si, 0.5-0.6 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 30ppm of T [ O ], blowing argon at the bottom of the LF furnace during tapping, wherein the flow of the argon is 100L/min, and the pressure of the argon is 0.3 MPa;
Step two, transmitting electricity for heating, wherein the current is 35000A, the heating and slagging time is 13min, the argon flow is 350L/min and the argon pressure is 0.4MPa in the slagging process, measuring the temperature and sampling;
Step three, adjusting the current to 30000A, adding lime in 2-3 batches, wherein the adding amount of the lime is 500kg, the flow rate of argon is adjusted to 50L/min, the pressure of the argon is 0.3MPa, adding fluorite according to the fluidity of slag, adjusting the slag amount of the slag to 10 kg/ton of steel, controlling the alkalinity to be 2.0, keeping the white slag for more than 15 minutes, and keeping FeO + MnO less than 1.0%;
Fourthly, deoxidizing the slag surface by adopting calcium carbide, adding the calcium carbide in 5 batches for slag adjustment, adding 1/5 of the total amount of the calcium carbide each time, wherein the time interval of adding the calcium carbide in each batch is 30s, and the total amount of the added calcium carbide is 1kg per ton of steel;
Step five, sampling and analyzing, adjusting according to target components, and improving the argon flow after adjusting the components, wherein the argon flow is 400L/min;
Step six, soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 15min, the flow of argon during soft blowing is 50L/min, the liquid level condition of the molten steel is observed during the soft blowing process, and the molten steel is prevented from being exposed;
and seventhly, adding ferrotitanium after the temperature of the molten steel is more than or equal to 1570 ℃ and the slag turns white, wherein the titanium content of the ferrotitanium is 28 percent, the recovery rate is 60 percent, feeding an iron-calcium wire at the speed of 250m and 3-5m/s after the components and the temperature before leaving the station meet the process requirements, and closing argon to finish the steel making of the LF furnace.
Example 6: an LF furnace refining process comprises the following steps: the initial carbon and sulfur content of the incoming molten steel of the LF furnace is C: 0.04%, S: 0.0091%;
firstly, adding qualified molten steel blown by a converter into an LF furnace, controlling the temperature of the molten steel at 1520 ℃, controlling the components of the molten steel to be 0.37-0.42 percent of C, 0.10-0.17 percent of Si, 0.5-0.6 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 30ppm of T [ O ], blowing argon at the bottom of the LF furnace during tapping, wherein the flow of the argon is 100L/min, and the pressure of the argon is 0.3 MPa;
step two, transmitting electricity for heating, wherein the current is 25000A, the heating and slagging time is 10min, the argon flow is 250L/min and the argon pressure is 0.3MPa in the slagging process, measuring the temperature and sampling;
Adjusting the current to 33000A, adding lime in 2-3 batches, wherein the adding amount of the lime is 515kg, the flow rate of argon is adjusted to 75L/min, the pressure of the argon is 0.35MPa, adding fluorite according to the fluidity of the slag, the slag amount of the slag is adjusted to 11 kg/ton of steel, the alkalinity is controlled to 2.5, the white slag is kept for more than 15 minutes, and FeO + MnO is less than 1.0%;
Fourthly, deoxidizing the slag surface by adopting calcium carbide, adding the calcium carbide in 5 batches for slag adjustment, adding 1/5 of the total amount of the calcium carbide each time, wherein the time interval of adding the calcium carbide in each batch is 30s, and the total amount of the added calcium carbide is 1kg per ton of steel;
step five, sampling and analyzing, adjusting according to target components, and improving the argon flow after adjusting the components, wherein the argon flow is 400L/min;
Step six, soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 15min, the flow of argon during soft blowing is 50L/min, the liquid level condition of the molten steel is observed during the soft blowing process, and the molten steel is prevented from being exposed;
And seventhly, adding ferrotitanium after the temperature of the molten steel is more than or equal to 1570 ℃ and the slag turns white, wherein the titanium content of the ferrotitanium is 28 percent, the recovery rate is 60 percent, feeding an iron-calcium wire at the speed of 250m and 3-5m/s after the components and the temperature before leaving the station meet the process requirements, and closing argon to finish the steel making of the LF furnace.
Example 7: an LF furnace refining process comprises the following steps: the initial carbon and sulfur content of the incoming molten steel of the LF furnace is C: 0.038%, S: 0.0092%;
Firstly, adding qualified molten steel blown by a converter into an LF furnace, controlling the temperature of the molten steel at 1520 ℃, controlling the components of the molten steel to be 0.37-0.42 percent of C, 0.10-0.17 percent of Si, 0.5-0.6 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 30ppm of T [ O ], blowing argon at the bottom of the LF furnace during tapping, wherein the flow of the argon is 100L/min, and the pressure of the argon is 0.3 MPa;
step two, transmitting electricity for heating, wherein the current is 25000A, the heating and slagging time is 10min, the argon flow is 250L/min and the argon pressure is 0.3MPa in the slagging process, measuring the temperature and sampling;
Step three, adjusting the current to 35000A, adding lime in 2-3 batches, wherein the adding amount of the lime is 530kg, the flow rate of argon is adjusted to 100L/min, the pressure of the argon is 0.4MPa, adding fluorite according to the fluidity of slag, the slag amount of the slag is adjusted to 12 kg/ton of steel, the alkalinity is controlled to 3.0, the white slag is kept for more than 15 minutes, and FeO + MnO is less than 1.0%;
fourthly, deoxidizing the slag surface by adopting calcium carbide, adding the calcium carbide in 5 batches for slag adjustment, adding 1/5 of the total amount of the calcium carbide each time, wherein the time interval of adding the calcium carbide in each batch is 30s, and the total amount of the added calcium carbide is 1kg per ton of steel;
Step five, sampling and analyzing, adjusting according to target components, and improving the argon flow after adjusting the components, wherein the argon flow is 400L/min;
Step six, soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 15min, the flow of argon during soft blowing is 50L/min, the liquid level condition of the molten steel is observed during the soft blowing process, and the molten steel is prevented from being exposed;
And seventhly, adding ferrotitanium after the temperature of the molten steel is more than or equal to 1570 ℃ and the slag turns white, wherein the titanium content of the ferrotitanium is 28 percent, the recovery rate is 60 percent, feeding an iron-calcium wire at the speed of 250m and 3-5m/s after the components and the temperature before leaving the station meet the process requirements, and closing argon to finish the steel making of the LF furnace.
example 8: a refining process of an LF furnace is different from that of the refining process of the embodiment 1 in that the total amount of calcium carbide added in the fourth step is 1.25kg per ton of steel.
example 9: a refining process of an LF furnace is different from that of the refining process of the embodiment 1 in that the total amount of calcium carbide added in the fourth step is 1.5kg per ton of steel.
example 10: the LF furnace refining process is different from the example 1 in that the argon flow in the step five is 450L/min.
example 11: the LF furnace refining process is different from the example 1 in that the argon flow in the fifth step is 500L/min.
example 12: the LF furnace refining process is different from the example 1 in that the sixth step is as follows: and soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 16min, the flow of argon during soft blowing is 55L/min, and the liquid level condition of the molten steel is observed in the soft blowing process so as to avoid the exposure of the molten steel.
example 13: the LF furnace refining process is different from the example 1 in that the sixth step is as follows: and soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 18min, the flow of argon during soft blowing is 60L/min, and the liquid level condition of the molten steel is observed in the soft blowing process so as to avoid the exposure of the molten steel.
Example 14: the LF furnace refining process is different from the refining process in the example 1 in that in the seventh step, the titanium content of the ferrotitanium is 29 percent, and the recovery rate is 65 percent.
Example 15: the LF furnace refining process is different from the refining process in the embodiment 1 in that the titanium content of the ferrotitanium in the step seven is 30 percent, and the recovery rate is 70 percent.
comparative example 1: the LF furnace refining process is different from the example 1 in that a conventional LF furnace refining treatment mode is adopted, namely, argon is blown in the refining process in a strong stirring mode, and the argon flow is constant at 600L/min.
the sulfur content and carbon content of the molten steels treated in examples 1 to 15 and comparative example 1 were measured, and the amount of carburization and desulfurization rate were calculated, and the results are shown in Table 1. As can be seen from the data in Table 1: by adopting the refining process, the desulfurization efficiency can reach more than 93 percent, the sulfur content of the LF furnace discharged from the station can be controlled within 6ppm, and the carburetion amount is not more than 50 ppm. And the conventional LF refining treatment mode is adopted, the sulfur content of the LF outlet is 20ppm, and the carburetion amount reaches 170ppm, so that the method can realize deep desulfurization of molten steel and effectively control the carburetion amount.
TABLE 1 carburetion and desulfurization rates of the treated steels of examples 1-15 and comparative example 1
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (7)
1. The LF furnace refining process is characterized by comprising the following steps:
Firstly, adding qualified molten steel blown by a converter into an LF furnace, controlling the temperature of the molten steel to be 1520-1540 ℃, controlling the components of the molten steel to be 0.37-0.42 percent of C, 0.10-0.17 percent of Si, 0.5-0.6 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 30ppm of T [ O ], and blowing argon gas at the bottom of the LF furnace during tapping;
step two, transmitting electricity for heating, wherein the current is 25000-35000A, the heating and slagging time is 10-13min, measuring the temperature and sampling;
Regulating the current to 30000-35000A, adding lime in 2-3 batches, wherein the adding amount of lime is 500-530kg, the flow of argon gas is regulated to 50-100L/min, and the pressure of the argon gas is 0.3-0.4 MPa;
deoxidizing the slag surface by adopting calcium carbide, adding the calcium carbide in batches for slag adjustment, wherein the total amount of the added calcium carbide is 1-1.5kg per ton of steel;
Step five, sampling and analyzing, adjusting according to target components, and improving the flow of argon after adjusting the components;
step six, soft blowing is carried out after the temperature and the components are qualified, the soft blowing time is 15-18min, the liquid level condition of the molten steel is observed in the soft blowing process, and the molten steel is prevented from being exposed;
Seventhly, adding ferrotitanium after the molten steel temperature is more than or equal to 1570 ℃ and the slag turns white, feeding an iron-calcium wire at a speed of 250 m/s and closing argon after the components and the temperature before leaving the station meet the process requirements, and finishing the steel making of the LF furnace;
the third step specifically comprises: adjusting the current to 30000-35000A, adding lime in 2-3 batches, wherein the adding amount of the lime is 500-530kg, the flow of argon is adjusted to 50-100L/min, the pressure of the argon is 0.3-0.4MPa, adding fluorite according to the fluidity of the slag, the amount of the slag is adjusted to 10-12 kg/ton steel, the alkalinity is controlled to 2.0-3.0, the white slag is kept for more than 15 minutes, and FeO + MnO is less than 1.0%.
2. the LF furnace refining process according to claim 1, wherein in the first step, the argon flow is 100-150L/min, and the argon pressure is 0.3-0.4 MPa.
3. The LF furnace refining process according to claim 1, wherein in the slagging process in the second step, the argon flow is 250-350L/min, and the argon pressure is 0.3-0.4 MPa.
4. the LF furnace refining process according to claim 1, wherein the step four specifically comprises: and deoxidizing the slag surface by using calcium carbide, adding the calcium carbide in 5 batches for slag regulation, wherein 1/5 of the total amount of the calcium carbide is added each time, the time interval of adding the calcium carbide in each batch is 30s, and the total amount of the added calcium carbide is 1-1.5 kg/ton of steel.
5. The LF furnace refining process according to claim 1, wherein the argon flow in the step five is 400-500L/mm.
6. the LF furnace refining process in the sixth step is characterized in that the flow rate of argon in soft blowing in the sixth step is 50-60L/min.
7. The LF furnace refining process in the step seven is characterized in that the titanium content of the ferrotitanium in the step seven is 28-30%, and the recovery rate is 60-70%.
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