KR100883820B1 - A method for smelting dephosphorization in ladle while steel manufacture process - Google Patents

Abstract

The present invention relates to a dephosphorization refining method in a ladle during a steelmaking step performed by tapping the molten steel refined in the converter of the steelmaking step into the ladle.

In particular, this is to increase the contact area between the slag and molten steel contained in the slag and molten steel in the ladle by inputting quicklime and formation at the same time as the tapping operation, and simultaneously performing bottom bubbling in the ladle. It features.

Accordingly, dephosphorization in the ladle can be performed to prevent segregation due to phosphorus in the final product, thereby making it possible to produce products required by demand.

Dynamic defect, long time wait, quicklime, fluorite, converter

Description

Process for smelting dephosphorization in ladle while steel manufacture process             

1 is a perspective view showing a general tapping work.

2a and 2b are graphs showing the behavior of phosphorus over time and the weight of alloys of conventional slag, respectively.

Figure 3a, b, c is a graph showing the dephosphorization relationship according to the input amount of quicklime, bottom bubbling, time and the input of quicklime according to the present invention, respectively.

Figure 4a is a flow chart related to the weighing ferroalloy at the time of the generation of atmospheric air in accordance with the present invention.

Figure 4b is a flow chart related to ferroalloy weighing during dynamic failure according to the present invention.

The present invention relates to a dephosphorization and refining method in ladle during steelmaking process, in particular, quicklime and formation at the same time as the tapping operation, bottom bubbling in the ladle at the same time performing the bottom bubbling (bottom bubbling) in the ladle, In the process of steelmaking to increase the contact area between airway slag and phosphorus contained in molten steel, dephosphorization work in the ladle to prevent the segregation of phosphorus in the final product to make the product required by the demand It relates to a dephosphorization refining method in a ladle.

In general, dephosphorization refining methods include dephosphorization refining methods in molten iron and dephosphorization refining methods in molten iron, and dephosphorization refining in molten iron requires recharging molten iron into the converter and increasing impurities in the molten steel in the converter. It was no exaggeration to say that the dephosphorization refining method in the converter was the main dephosphorizing refining method.

The dephosphorization work in the molten iron is made by pulverizing oxygen mill scale, quicklime, etc. through the lance to blow and reduce the 0.08 to 0.10 wt% of P contained in the molten iron to 0.03 to 0.04 wt%. The dephosphorization reaction proceeds with the reaction of FeO in the mill scale with quicklime of [P] and high base in molten iron.

As described above, the dephosphorization work in the molten iron is charged to the converter 1 again, and oxygen is supplied through the lance 5 at the upper portion thereof to remove the impurities contained in the molten iron to perform the converter refining operation required by the consumer.

However, demineralization work up to 0.012 ~ 0.025% by weight is added to the molten iron and dephosphorized molten iron in the converter as described above, but as shown in Table 1, decontamination work is not properly performed during refining work in the converter. During the tapping operation, quality defects occur outside the component range of [P], which is 0.002 ~ 0.004% by weight.

In addition, the above-mentioned causes of poor quality are often caused when the inside of the converter has cooled down due to the long-term air generation, and when the top of the kneader material is charged in order to protect the purified water TOP, tapping hole exchange TOP, and the furnace. In the above case, the cause of poor quality is 1300 ~ 1500 ℃ in normal operation, but in case of long-time waiting, the thermal burden increases to 700 ~ 900 ℃, which causes the poor quality of slag. Becomes

In addition, even during normal operation, as shown in FIG. 2, the dynamic decay curve can be estimated according to the temperature of the molten steel and the amount of carbon remaining in the molten steel during the dynamic temperature measurement at 80% of the drilling operation. have.

In the case of the conventional converter refining operation, it is possible to control the normal debonding curve, and to control the stable [p] even in the case of dynamic defect. In the case of dynamic defect, draw the defect delineation curve, and in the case of 0.002 ~ 0.004 as shown in Table 1 [P] is increased by weight percent, and the above debonding curve estimation is based on long term performance.

Table 1

fair ingredient(%) range C Mn Si P S Al maximum 0.05 0.2 0.03 0.020 0.02 0.06 Lower limit 0.02 0.3 0 0 0 0.02 converter 0.035 0.08 0 0.022 0.014 BAP 0.037 0.25 0 0.022 0.014 0.035 RH Primary 0.037 0.25 0 0.022 0.014 0.038 RH2 tea 0.037 0.25 0 0.022 0.014 0.038 Sogang 1st 0.036 0.25 0 0.022 0.014 0.032 Sogang 2nd 0.036 0.25 0 0.022 0.014 0.033

However, as described above, the media production and sales conditions contrary to the requirements of the demand price is not met, so that the sale is not made immediately, and there is a problem in that product defects occur due to segregation of [p] present in molten steel.                         

As a result, the work load of the workers is increased by relying on the dephosphorization work only in the refining work of the converter.

In addition, when [p] was high in the post-process at 0.002 to 0.004% by weight, the workers introduced ladle into the converter side, added quicklime and formation, and buddling, but dissolved oxygen in the molten steel was killed by deoxidizer. The quicklime of the high base air into the molten steel in the upper part of the molten steel does not produce 4CaO, P ₂ O ₅ because it does not have oxygen to react with [p] in the molten steel even though it reacts with the [p] in the molten steel. I couldn't.

In addition, there is no dephosphorization work in the ladle, and it depends solely on the dephosphorization work in the converter to increase the work load of the worker and to remove the molten steel in the converter. There was a problem that the manufacturing cost is rising.

The object of the present invention to improve this is to improve the dephosphorization efficiency in the ladle during tapping, to increase the basicity in the ladle, to lower the melting point of quicklime, and to perform the bottom bubbling in the ladle. By increasing the contact area between molten steel and basic slag to provide dephosphorization refining in the ladle during the steelmaking process to perform dephosphorization in the ladle during the steelmaking operation.

In order to achieve the above objects,

Weighing and preparing quicklime, fluorspar, deoxidizer and ferroalloy;

Supplying quicklime, which is weighed, and fluorite to be fed to the input hopper;

Smelting the ladle through an injection hopper into which quenching and fluorspar are injected by completing the steel in the converter;

Performing bottom bubbling at the bottom of the ladle;

There is provided a dephosphorization refining method in a ladle during a steelmaking process that consists of a step of introducing a deoxidizer and ferroalloy, which are previously weighed during tapping in the ladle.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the present invention used the same reference numerals with reference to the conventional Figure 2 showing the tapping operation.

In addition, bottom bubbling in the present invention is performed to improve cleanliness of molten steel by separating and injuring impurities present in molten steel in the ladle during the tapping operation in the converter. In order to stir the molten steel in the ladle by supplying an inert gas argon to the lower part of the ladle by installing a role of lower odor in the ladle, the dynamic lamination is a blow to estimate the temperature in the furnace and the component behavior in the furnace during the converter drilling. It is to measure the sub lance at 80% of the work.                     

3 to 5, the present invention, when the molten steel tapping into the ladle 40 from the converter (1) is used to calculate up to 200 times, the tapping time of about 10 minutes during one tapping work It takes time, and it is managed for about 4 minutes when it is time to exchange the gate.

In addition, the operator loads molten iron and scrap metal into the converter 1, supplies oxygen through the lance at the upper portion, inert gas at the lower portion, and removes impurities from the molten iron by adding auxiliary materials such as quicklime. Done.

At this time, the amount of subsidiary materials to be input is changed according to the quality required by the demand price, and the amount of ferroalloy is also changed.

In addition, the operator weighs the top, tap hole exchange top, and ferroalloy shown in FIG. 10a after a long time of waiting for frequent occurrence of pain defects, and weighs the ferroalloy as shown in FIG. Do this.

As a way to increase the dephosphorization rate. 1) Oxygen concentration in the slag increases basicity, 2) lowers P ₂ O ₅ activity and temperature, 3) increases slag and contact area (increases the stirring force), 4) increases the material movement speed (slag viscosity decreases), etc. The dephosphorization rate is increased by the method of.

In the same manner as above, in order to increase the dephosphorization efficiency in the ladle, the operator injects the quicklime and the fluorspar previously weighed into the ferroalloy hopper 38 in the ladle 40 at the same time as the tapping work.

Subsequently, quicklime and fluorspar collide with the tapping stream introduced from the converter, and part of it is commodified, and the quicklime and fluorite are combusted by the stirring force naturally generated by the tapping stream fall.

Further, at the same time as the tapping and the bottom (bottom) is installed in the bottom (bottom) is added to the inert gas argon to perform the bottom bubbling to generate bubbles, such as bubbles, after performing dephosphorification refining operation, ladle 40 The deoxidizer and ferroalloy are added at 1/2 time in the chamber.

When the quicklime is added to the ladle 40 during the tapping operation as described above, the purpose of the quicklime input is to meet the dissolved oxygen in the molten steel while the quicklime melts and increase the oxygen concentration in the slag. , Increase the basicity in the slag in the ladle.

Fluorite is added to lower the melting point of quicklime because the quicklime has a melting point of 2570 ° C.

And, bottom bubbling in the ladle 40 is carried out to increase the dephosphorification efficiency while increasing the contact area between the molten steel and the high base slag,

React as in the following scheme

[Scheme 1]

2 [P] + 5 [FeO] + 4CaO = 4CaO.P ₂ O ₅ + 5Fe

[Scheme 2]                     

log KP = (78,735 / T)-33.44

To explain this, as shown in Scheme 1, the phosphorus compound in a stable form is made in the slag to perform dephosphorization and refining in the ladle 40.

Referring to the operation of the present invention made of such a configuration as follows.

As shown in Figures 3 to 9, the present invention, 600 ~ 1200Kg of quicklime during the tapping operation, 100 ~ 200kg fluorite is added to the natural stirring force due to falling of tapping flow and bottom bubbling of 0.6 ~ 1.2N㎡ During the tapping operation, dephosphorization work is performed by increasing the contact with phosphorus in the molten steel and the high base in slag, and dephosphorization work is carried out to dehaling up to 1/2 in the molten steel ladle during tapping, and then deoxidizer and ferroalloy are added. To induce dephosphorization in molten steel.

A checklist as shown in Table 2 was prepared by the experimental design method.

[Table 2]

River Steel grade Converter [P] BAP [P] Quicklime input Input B / B Etc A32514 HW04025E3 18 17 400 50 - A32515 HW04025E3 15 14 400 50 - A32516 HW04025Z 19 17 600 80 0 A32517 HW04015L 14 12 600 80 0 A32518 HW15070G 19 17 600 80 0 A32519 HW15070G 15 13 600 80 0  (syncopation) A35689 HW08060K 15 11 1200 200 0 A35690 HW08050E 19 15 1200 200 0 A35691 HW10050F 22 19 1200 200 0 A35692 HW10050F 18 13 1200 200 0 A35693 HW04025A 23 21 1400 200 0 A35694 HW04025E3 22 20 1400 200 0 A35695 HW04025E3 18 17 1600 200 0 A35696 HW04025E3 19 18 1600 200 0 A35697 HW04025Z 16 15 1600 200 0

As a result, as shown in Figure 3, in order to perform 0.002 ~ 0.004% by weight dephosphorization in the dephosphorization refining in the ladle after tapping, the amount of quicklime is preferably 600 ~ 1200kg, when a large amount of quicklime is put in 2-4 minutes The use of too much quicklime is counterproductive because of the dephosphorization work.

In the case of fluorspar, the more it is used, the better, but 100-200 kg is preferable.

In addition, in order to maximize the dephosphorization effect in the ladle 40, as shown in Figure 3b, bottom bubbling is preferably performed at about 0.6 to 1.2 Nm 3 / Min. The same dephosphorization effect was achieved, and in the case of 1.2 Nm 3 or more, it caused the molten steel temperature too much.

When the ladle refining operation is performed in the above manner, as shown in FIG. 3C, the dephosphorization refining time in the ladle 40 increases.

As described above, according to the present invention, at the same time as the tapping work, quick lime and fluorspar are put into the ladle to make slag with high base, and to perform dephosphorization refining with undeoxidized molten steel, and to perform bottom bubbling during tapping work to maximize dephosphorization refining effect, and ladle. By adding a deoxidizer and ferroalloy therein, there is an excellent effect in dephosphorization refining in the ladle.

In addition, bottom bubbling is performed to reduce dissolved oxygen in molten steel by reacting [C] and dissolved oxygen present in molten steel, reducing the amount of deoxidizer added during tapping, improving the error rate of ferroalloy, and By performing dephosphorization, the segregation of phosphorus in the final product can be prevented to make the product required by the demand.

While the invention has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention as provided by the following claims. I would like to clarify that those who have knowledge of this can easily know.

Claims (2)

Weighing and preparing quicklime, fluorspar, deoxidizer and ferroalloy; Supplying weighed quicklime and fluorspar to the input hopper; A step of tapping the ladle through an input hopper into which quicklime and fluorspar are pre-injected after the steel is blown in the converter; Performing bottom bubbling at the bottom of the ladle from which the river is pulled out; A dephosphorization and refining method in a ladle during a steelmaking process comprising a step of inputting a deoxidizer and ferroalloy weighed in advance during tapping in the ladle. The method of claim 1, wherein the deoxidizing agent and ferroalloy, which are previously weighed during tapping in the ladle, are introduced into the ladle, wherein deoxidizer and alloying iron are added when the molten steel in the ladle is 1/2. Dephosphorization refining method in ladle.

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