CN111394535A - Step-by-step KR stirring desulfurization method for molten iron - Google Patents
Step-by-step KR stirring desulfurization method for molten iron Download PDFInfo
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- CN111394535A CN111394535A CN202010233904.4A CN202010233904A CN111394535A CN 111394535 A CN111394535 A CN 111394535A CN 202010233904 A CN202010233904 A CN 202010233904A CN 111394535 A CN111394535 A CN 111394535A
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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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
- B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
- B01F27/90—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis with paddles or arms
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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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Abstract
The invention discloses a step-by-step KR stirring desulfurization method for molten iron, and belongs to the technical field of external desulfurization of the molten iron before converter steelmaking. The method comprises the following steps: firstly, slagging off molten iron, measuring the liquid level depth, measuring the temperature and sampling; step two, inserting the stirrer into the shallow layer of the molten iron liquid level, and rotating to the working rotating speed; step three, keeping the stirring depth and the rotating speed, and adding a desulfurizing agent; fourthly, adjusting the insertion depth and the working rotating speed of the stirrer; and step five, stirring until the desulfurization is finished, and slagging off, measuring the temperature and sampling again. The invention adopts shallower insertion depth of the stirrer and lower stirring speed in the initial stirring stage, which is beneficial to entrainment and mixing dispersion of the desulfurizer and can reduce energy consumption and blade abrasion; and the deep stirring depth is adopted in the later stirring stage, so that the stirring and the uniform mixing of a molten pool are facilitated, the floating stroke of the desulfurizer is increased, the stirring and mixing area of the molten pool is effectively enlarged, and the reaction kinetic condition of the bottom area of the molten pool is improved.
Description
Technical Field
The invention relates to the technical field of external desulfurization of molten iron before converter steelmaking, in particular to a step-by-step KR stirring desulfurization method for molten iron.
Background
The mechanical stirring desulfurization of molten iron is to mix and contact molten iron and a desulfurizing agent by rotating and stirring a stirrer inserted into the molten iron in a molten iron tank to perform desulfurization, and mainly includes a Rhine method and a KR (Kambara reactor) method. The stirrer used by the two molten iron mechanical stirring desulfurization methods consists of a rotating shaft and stirring blades, the four stirring blades are uniformly distributed in a cross shape along the circumferential direction of the rotating shaft, and the stirrer inserts molten iron along the central line of a molten iron tank; the only difference is the depth of the stirrer inserted into the molten iron. The Rhine method only inserts the stirring blade of the stirrer partially into the molten iron, makes the molten iron on the upper part of the molten iron tank and the desulfurizer on the surface of the molten iron form a vortex by stirring, and makes the molten iron in the whole molten iron tank reach an upper desulfurization area by circulating flow to realize desulfurization; KR law is a certain degree of depth with the stirring leaf of agitator immerse in the molten iron, and rotatory stirring through the agitator makes the desulfurizer on the molten iron surface be drawn into the molten iron and mixes the desulfurization, has enlarged swirl degree of depth and desulfurization reaction region, has strengthened the circulation flow of molten iron, has reached the combined effect of accelerating desulfurization speed, shortening desulfurization time, improvement desulfurization efficiency, reduction desulfurizer consumption. Due to the excellent use performance of the KR method, the KR method becomes the only method which is popularized and applied to mechanical stirring desulfurization of molten iron at home and abroad at present.
However, according to the limited research report of KR stirring desulfurization flow state at home and abroad, the KR stirring desulfurization flow state is divided into a stirring center forced vortex region and a free vortex region outside the region, and the forced vortex region is a poor mixing region because no relative movement between liquid microelements exists; and the free vortex area causes relative motion among liquid microelements due to the cyclic motion, thereby playing a role in mixing and dispersing. When the stirring is rotated, the particles in the forced vortex region and fluid particles all make concentric circular motion around the shaft, the relative speed is very low, effective mixing and dispersion cannot be carried out, and only between the forced vortex region and the end region of the blade, the solid-liquid turbulence is violent, and the region with the strongest mass transfer, transmission and dispersion mixing is provided. The depth of the solid particles involved in the liquid is approximately equal to the depth of the liquid level depression, and after the particles are involved in the liquid, the particles are dispersed due to turbulence between the forced vortex region and the blade end region, are 'ejected' along the radial direction under the action of centrifugal force, then float up under the action of buoyancy force, and are subjected to the involved-dispersed-involved cyclic motion at the position above the 'ejecting' region. Therefore, the dynamic mechanism of KR stirring and desulfurizing transmission of the molten iron is local entrainment mixing and radial shearing dispersion; research shows that the ratio of the radius of the forced vortex region to the radius of the impeller of the stirrer is approximately 0.7 in the KR stirring desulfurization process, the effective stirring area of the stirring blades is only 30%, and how to improve the mixing and dispersing conditions of the desulfurizer in molten iron is an important way for improving the KR stirring desulfurization efficiency.
Therefore, a large amount of research work is carried out by related scholars from the aspects of a process method, operation process parameters, a stirrer structure and the like so as to improve the dynamic condition of mechanical stirring desulfurization and further improve the desulfurization use performance of the KR method.
(1) The KR method is based on the KR method, high-pressure nitrogen is blown into the tank through an air brick arranged at the bottom of the tank to promote floating of desulfurization slag in molten iron, so that the aim of improving the desulfurization speed and the purity of the molten iron is fulfilled, but the floating of bottom-blown gas is opposite to the entrainment direction of a desulfurizing agent, so that the desulfurizing agent is not beneficial to reaching the bottom of a molten pool, the retention time of the desulfurizing agent in the molten iron is shortened, and the reaction kinetic condition is limited to a certain extent.
(2) And (5) improving operation process parameters. Several iron and steel enterprises at home and abroad adopt a mode of increasing the rotating speed of the stirrer in order to make up and improve the dynamic conditions of desulfurization, such as: the highest stirring speed of the Chuanwei 120-ton hot metal tank reaches 140 revolutions per minute; according to data reports, many iron and steel enterprises in Japan also adopt the means of increasing the rotating speed of the stirrer to improve the desulfurization kinetic conditions, and the rotating speed range is set to be 100-. But due to the limitation of the performance of the stirring equipment, the range of increasing the stirring rotating speed is limited, and the effect of improving the desulfurization dynamic condition is also very limited; meanwhile, the increase of the stirring speed aggravates the abrasion of the stirrer, the liquid level of the molten iron rises, the service life of the stirrer is shortened, and the loading capacity of the molten iron tank is reduced.
(3) The improvement of the stirrer structure, the modification of the molten iron desulfurization technology (interpretation), the tai-gang translation, 1994, (1), 20-25 "reports that the influence of the diameter of a stirrer impeller and the shape of a stirring blade on desulfurization dynamics conditions was first studied in the last 90 th era of iron manufacture in Japan Sumitomo Metal deer island, and the improvement of the dynamics of a stirrer impeller expanding diameter and a blade convex arc stirring surface was proposed, wherein the special-shaped stirring blade was not popularized and applied because of difficulty in maintaining the shape in actual use, the stirrer impeller expanding diameter was applied in some steel enterprises at home and abroad, but the effective molten iron loading capacity and the stirrer service life of a molten iron tank were affected due to a high molten iron liquid level rise, and the safety of production due to a large vibration of a stirring apparatus, the stirrer for molten iron desulfurization was disclosed as a three-blade stirrer for stirring the stirrer with both a stirring blade surface and a back surface both inclined forward, and the stirrer for stirring the desulfurization surface and the back surface were enhanced by a spiral blade forward-inclined surface structure, and a spiral stirring blade-reinforced stirring surface was disclosed as a spiral stirring blade front-reinforced, a spiral stirring blade-reinforced stirring blade-stirring-enhancing spiral-stirring-enhancing effect, a spiral-stirring-enhancing spiral-stirring-enhancing spiral-stirring-enhancing-stirring-head, which is not only has been used for the front-stirring-.
Disclosure of Invention
1. Technical problem to be solved by the invention
The invention aims to solve the problems that the entrainment and dispersion effects of a desulfurizer in molten iron are poor, blades of a stirrer are consumed by an improved method, and the effect is still unsatisfactory in the conventional KR stirring method, and provides a step-by-step KR stirring desulfurization method for molten iron.
2. Technical scheme
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the invention relates to a step-by-step KR stirring desulfurization method for molten iron, which comprises the following steps of:
firstly, slagging off molten iron, measuring the liquid level depth, measuring the temperature and sampling;
step two, inserting the stirrer into the shallow layer of the molten iron liquid level, and rotating to the working rotating speed;
step three, keeping the stirring depth and the rotating speed, and adding a desulfurizing agent;
fourthly, adjusting the insertion depth and the working rotating speed of the stirrer;
and step five, stirring until the desulfurization is finished, and slagging off, measuring the temperature and sampling again.
In a further improvement of the invention, in the second step, the insertion depth of the stirrer is 1/8-3/8 of the liquid level depth.
As a further improvement of the invention, in the third step, the insertion depth and the working speed of the stirrer are kept for 3-5 min.
As a further improvement of the invention, the insertion depth of the stirrer in the fourth step is adjusted to be 5/8-7/8 of the liquid level depth, and the working rotating speed of the stirrer is increased by 10-20% compared with the rotating speed of the stirrer in the second step.
In the third step, the desulfurizer is blown to the hot metal ladle through nitrogen from the bin, and the pressure of the nitrogen blowing is 0.1-0.15 MPa.
As a further improvement of the invention, in the third step, the desulfurizer is conveyed by a feeding pipe, the feeding pipe comprises an inclined straight pipe section and a bent short pipe section, a feeding port is vertically downward, and the desulfurizer is conveyed by gas in a feeding mode.
As a further improvement of the invention, in the third step, the distance from the feeding port of the feeding pipe to the vortex surface is kept to be less than or equal to 0.4m, and the value range of the distance L from the desulfurizing agent falling point to the central line of the stirring shaft is controlled to be r < L < L0Wherein r is the radius of the rotation axis of the agitator, L0The distance between the intersection point of the stirring vortex liquid level and the upper end surface of the stirring blade and the central axis of the rotating shaft of the stirrer.
As a further improvement of the invention, the desulfurizer added in the step three comprises the following components in percentage by mass: CaO: 58 to 60% of Al2O3：12～14％、SiO2：3～5％、MgO：10～11％、CaF2: 2-3% of soda ash: 3 to 4% of K2O：3～5％、Na2O: 3-4%; the desulfurizer is powder subjected to premelting treatment, and the particle size is 0.5-1 mm.
As a further improvement of the invention, in the step one, the slag is removed until the exposed area of the molten iron liquid surface reaches more than 60 percent; and fifthly, slagging off until the exposed area of the liquid level of the molten iron reaches more than 80%.
3. Advantageous effects
Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:
(1) according to the step-by-step KR stirring desulfurization method for the molten iron, the depth of the stirrer inserted into the molten iron and the stirring speed are controlled, the circulating entrainment, mixing and dispersion of the desulfurizer in the molten iron are realized through shallow stirring and deep stirring, and the desulfurization of the molten iron in one pot is completed through the contact desulfurization reaction of the desulfurizer and the molten iron.
(2) Compared with the traditional KR method, the step-by-step KR stirring desulfurization method has the best stirrer insertion depth (1/2 molten pool depth) and meets the desulfurization requirement by increasing the rotating speed of the stirrer, and the shallow stirrer insertion depth is adopted in the initial stirring stage, so that entrainment of a desulfurizer added in the initial stirring stage is facilitated; meanwhile, the mixing and dispersion of the desulfurizer can be realized by adopting a lower stirring rotating speed, and the energy consumption and the blade abrasion at the initial stirring stage are favorably reduced.
(3) Compared with the traditional method in which the depth of the stirrer is constant all the time, the step-by-step KR stirring desulfurization method for molten iron has the advantages that the insertion depth of the stirrer is adjusted at the later stage of stirring, and the deeper stirring depth is adopted, so that the stirring and the uniform mixing of a molten pool are facilitated, and the uniform mixing time of the molten pool is shortened; meanwhile, the deeper insertion depth of the stirrer increases the upward floating range of the desulfurizer, effectively enlarges the stirring and mixing area of the molten pool, and obviously improves the reaction kinetic condition of the bottom area of the molten pool.
Drawings
FIG. 1 is a schematic view showing the depth of insertion of a stirrer at the initial stage of stirring in the present invention;
FIG. 2 is a schematic view of the depth of insertion of the agitator at the end of the mixing operation in accordance with the present invention;
fig. 3 is a schematic view of the structure and position of the feeding pipe of the present invention.
The reference numerals in the schematic drawings illustrate:
1. a stirrer; 2. a hot-metal ladle; 3. a feeding pipe.
Detailed Description
For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings and examples.
Example 1
With reference to fig. 1 and fig. 2, the step-by-step stirring desulfurization method for molten iron KR of the present embodiment includes the following steps:
step one, slagging off molten iron until the exposed area of the liquid level of the molten iron reaches more than 60%, measuring the depth of the liquid level, recording as H, and measuring and sampling the temperature;
step two, inserting the stirrer 1 into the molten iron at a height of 1/4 degrees of the liquid level depth, namely the insertion depth H of the stirrer 1 is H/4, and rotating to the working rotating speed;
step three, adding a desulfurizer, and keeping the insertion depth and the working speed of the stirrer 1 for 4 min;
in the step, the desulfurizer is blown to a molten iron tank 2 from a storage bin by nitrogen at the blowing pressure of 0.1MPa, the storage bin is connected with the molten iron tank 2 by a feeding pipe 3, the feeding pipe 3 comprises an inclined straight pipe section and a bent short pipe section, a feeding port is vertically downward, the distance from the feeding port to a vortex surface is kept to be less than or equal to 0.4m, and the value range of the distance L from a desulfurizer falling point to the central line of a stirring shaft is controlled to be r less than L less than L0Wherein r is the radius of the rotation axis of the agitator 1, L0The distance between the intersection point of the liquid level of the stirring vortex and the upper end surface of the stirring blade and the central axis of the rotating shaft of the stirrer 1 is shown in figure 3; through the control of pressure and distance, the desulfurizer can not be absorbed by a dust cover outside the hot metal ladle 2 in the feeding process, and the feeding point of the desulfurizer is accurately controlled, so that the desulfurizer is easier to be sucked and diffused by the stirrer 1.
In addition, the desulfurizing agent adopted in this embodiment is a pre-melted powder with a particle size of 0.8mm, and comprises the following components in percentage by mass: CaO: 60% of Al2O3：12％、SiO2：5％、MgO：11％、CaF2: 3% of soda ash: 3%, K2O：3％、Na2O: 3 percent. Wherein, Al2O3The fluxing agent is good, is beneficial to promoting the melting of the slag at a lower temperature, is quick to form slag, and can improve the dynamic condition of desulfurization; small amount of Na2And O has strong basicity and is more tightly combined with phosphide in molten iron, so that the desulfurization capability of the slag can be improved.
Step four, adjusting the stirring insertion depth and the stirring speed, inserting the stirrer 1 to 3/4 of the liquid level depth, namely H is 3H/4, and simultaneously increasing the stirring speed by 15% compared with the stirring speed of the stirrer 1 in the step two;
and step five, keeping the insertion depth and the stirring rotating speed of the stirrer 1 until the desulfurization process is finished, slagging off again until the exposed area of the molten iron liquid surface reaches more than 80%, and measuring the temperature and sampling.
It is worth to be noted that, in the conventional KR molten iron mechanical stirring desulfurization process, the rotation of the stirrer 1 forms a vortex, the desulfurizing agent added on the molten iron liquid surface enters the molten iron under the entrainment effect of the vortex, is dispersed by the rotating centrifugal force effect of the stirrer 1, and floats upwards under the buoyancy effect. The circulating entrainment and the mixing dispersion of the desulfurizer in the molten iron are realized through the circulating operation of the three processes, and the desulfurization of the molten iron in one pot is completed through the contact desulfurization reaction of the desulfurizer and the molten iron.
The related research results show that the depth of the vortex formed by stirring has stronger correlation with the diffusion characteristic of molten pool particles; only when the stirring vortex depth is greater than the end part of the blade of the stirrer 1, the desulfurizer particles can be diffused in molten iron, namely, the desulfurizer is sucked between the blades through vortex entrainment, and the mixing and the dispersion of the desulfurizer can be realized only under the action of the blades. Therefore, in order to make the vortex depth reach between the blades, the vortex depth must be increased by relying on higher rotating speed in actual production; at the same time, the depth of insertion of the stirrer 1 cannot be too great, otherwise it is not advantageous for the vortex to go down between the blades of the stirrer 1. As can be seen from the above process, in the stirring desulfurization process, the rotation of the stirrer 1 not only realizes the reeling in and dispersing of the desulfurizing agent into the molten iron at the initial stirring stage, but also realizes the uniform mixing of the molten pool at the later stirring stage. Therefore, the conventional stirring desulfurization process has the optimal insertion depth (1/2 molten pool depth) of the stirrer 1, and meets the process requirements by increasing the rotating speed of the stirrer 1, so that the stirring energy consumption is high, and the abrasion of the stirrer 1 is increased; meanwhile, the insertion depth of the stirrer 1 in the later stage of stirring is relatively shallow, so that the upward floating stroke of the desulfurizer is relatively short, the mixing area of the desulfurizer and the molten iron is small, the stirring and mixing effect of the molten iron at the bottom is poor, and the desulfurization efficiency is influenced.
In the embodiment, the shallow insertion depth of the stirrer 1 is adopted in the initial stirring stage, so that entrainment of the added desulfurizer in the initial stirring stage is facilitated; meanwhile, the mixing and dispersion of the desulfurizer can be realized by adopting a lower stirring rotating speed, and the energy consumption and the blade abrasion at the initial stirring stage are favorably reduced. The insertion depth of the stirrer 1 is adjusted at the later stage of stirring, and the deeper stirring depth is adopted, so that the stirring and the uniform mixing of a molten pool are facilitated, and the uniform mixing time of the molten pool is shortened; meanwhile, the deeper insertion depth of the stirrer 1 increases the upward floating range of the desulfurizer, effectively enlarges the stirring and mixing area of the molten pool, and obviously improves the reaction kinetic condition of the bottom area of the molten pool.
Example 2
The step-by-step KR stirring desulfurization method for molten iron comprises the following steps:
step one, slagging off molten iron until the exposed area of the liquid level of the molten iron reaches more than 60%, measuring the depth of the liquid level, recording as H, and measuring and sampling the temperature;
step two, inserting the stirrer 1 into the molten iron at a height of 3/8 degrees of the liquid level depth, namely the insertion depth H of the stirrer 1 is 3H/8, and rotating to the working rotating speed;
step three, adding a desulfurizer, and keeping the insertion depth and the working speed of the stirrer 1 for 4 min; wherein the blowing pressure is 0.12MPa, the particle size of the desulfurizer is 0.5mm, and the desulfurizer comprises the following components in percentage by mass: CaO: 58% of Al2O3：14％、SiO2：4％、MgO：10％、CaF2: 2% of soda ash: 3.5% and K2O：5％、Na2O：3.5％；
Step four, adjusting the stirring insertion depth and the stirring speed, inserting the stirrer 1 to 5/8 of the liquid level depth, namely H is 5H/8, and simultaneously increasing the stirring speed by 20% compared with the first step;
and step five, keeping the insertion depth and the stirring rotating speed of the stirrer 1 until the desulfurization process is finished, slagging off again until the exposed area of the molten iron liquid surface reaches more than 80%, and measuring the temperature and sampling.
Example 3
The step-by-step KR stirring desulfurization method for molten iron comprises the following steps:
step one, slagging off molten iron until the exposed area of the liquid level of the molten iron reaches more than 60%, measuring the depth of the liquid level, recording as H, and measuring and sampling the temperature;
step two, inserting the stirrer 1 into the molten iron at a height of 1/8 degrees of the liquid level depth, namely the insertion depth H of the stirrer 1 is H/8, and rotating to the working rotating speed;
step three, adding a desulfurizer, and keeping the insertion depth and the working speed of the stirrer 1 for 4 min; wherein the blowing pressure is 0.15MPa, the particle size of the desulfurizer is 1mm, and the desulfurizer comprises the following components in percentage by mass: CaO: 59% of Al2O3：13％、SiO2：3％、MgO：10.5％、CaF2: 2.5%, soda: 4%, K2O：4％、Na2O：4％；
Step four, adjusting the stirring insertion depth and the stirring speed, inserting the stirrer 1 to 7/8 of the liquid level depth, namely H is 7H/8, and simultaneously increasing the stirring speed by 10% compared with the stirring speed of the stirrer 1 in the step two;
and step five, keeping the insertion depth and the stirring rotating speed of the stirrer 1 until the desulfurization process is finished, slagging off again until the exposed area of the molten iron liquid surface reaches more than 80%, and measuring the temperature and sampling.
The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.
Claims (9)
1. A step-by-step KR stirring desulfurization method for molten iron is characterized by comprising the following steps:
firstly, slagging off molten iron, measuring the liquid level depth, measuring the temperature and sampling;
step two, inserting the stirrer (1) into the shallow layer of the liquid level of the molten iron, and rotating to the working rotating speed;
step three, keeping the stirring depth and the rotating speed, and adding a desulfurizing agent;
fourthly, adjusting the insertion depth and the working rotating speed of the stirrer (1);
and step five, stirring until the desulfurization is finished, and slagging off, measuring the temperature and sampling again.
2. The method for KR stirring desulfurization of molten iron in step mode according to claim 1, wherein: in the second step, the insertion depth of the stirrer (1) is 1/8-3/8 of the liquid level depth.
3. The method for KR stirring desulfurization of molten iron in step-by-step manner as claimed in claim 2, wherein: and in the third step, the insertion depth and the working speed of the stirrer (1) are kept for 3-5 min.
4. The step-by-step KR stirring desulfurization method of claim 3, which is characterized in that: in the fourth step, the insertion depth of the stirrer (1) is adjusted to 5/8-7/8 of the liquid level depth, and the working rotating speed of the stirrer (1) is increased by 10-20% compared with the rotating speed of the stirrer (1) in the second step.
5. The step-by-step KR stirring desulfurization method of claim 4, which is characterized in that: and in the third step, the desulfurizer is blown to the hot metal ladle (2) from the bin through nitrogen, and the pressure of the nitrogen blowing is 0.1-0.15 MPa.
6. The method for KR stirring desulfurization of molten iron in step mode according to claim 5, wherein: in the third step, the desulfurizer is conveyed by a feeding pipe (3), the feeding pipe (3) comprises an inclined straight pipe section and a bent short pipe section, a feeding port is vertically downward, and the desulfurizer is conveyed by gas in a feeding mode.
7. The KR stirring desulfurization method as claimed in claim 5, wherein in the third step, the distance from the feeding port of the feeding pipe (3) to the vortex surface is kept less than or equal to 0.4m, and the distance L from the desulfurizing agent dropping point to the center line of the stirring shaft is controlled to have a value r < L < L0Wherein r is the radius of the rotation axis of the stirrer (1), L0Is the distance between the intersection point of the stirring vortex liquid level and the upper end surface of the stirring blade and the central axis of the rotating shaft of the stirrer (1).
8. The method for KR stirring desulfurization of molten iron in step mode according to claim 7, wherein: the desulfurizing agent added in the third step comprises the following components in percentage by mass: CaO: 58 to 60% of Al2O3：12～14％、SiO2：3～5％、MgO：10～11％、CaF2: 2-3% of soda ash: 3 to 4% of K2O：3～5％、Na2O: 3-4%; the desulfurizer is powder subjected to premelting treatment, and the particle size is 0.5-1 mm.
9. The method for KR stirring desulfurization of molten iron in step mode according to claim 8, wherein: in the first step, slag is removed until the exposed area of the liquid level of molten iron reaches more than 60%; and fifthly, slagging off until the exposed area of the liquid level of the molten iron reaches more than 80%.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111979375A (en) * | 2020-08-19 | 2020-11-24 | 武汉钢铁有限公司 | Molten iron KR stirring mixing characteristic quantitative characterization method and intelligent desulfurization method |
| CN113073167A (en) * | 2021-03-15 | 2021-07-06 | 鞍钢股份有限公司 | KR desulfurization method for high-sulfur molten iron |
| CN113832282A (en) * | 2021-10-14 | 2021-12-24 | 四川德胜集团钒钛有限公司 | Vanadium-containing molten iron desulfurization method |
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| CN113073167A (en) * | 2021-03-15 | 2021-07-06 | 鞍钢股份有限公司 | KR desulfurization method for high-sulfur molten iron |
| CN113832282A (en) * | 2021-10-14 | 2021-12-24 | 四川德胜集团钒钛有限公司 | Vanadium-containing molten iron desulfurization method |
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