JPS613814A - Method for efficiently pretreating and refining molten iron with turntable - Google Patents

Abstract

PURPOSE:To improve considerably the efficiency of refining of molten iron by placing a turntable which turns in a fixed cycle by intermittent movement by a fixed angle and by arranging refining stations at positions corresponding to the fixed angle so as to carry out desiliconization, dephosphorization, desulfurization and slag discharge. CONSTITUTION:A turntable which turns along the same circumference by intermittent movement by a prescribed angle is placed, and a desiliconizing station 14, a slag discharging station 15, a dephosphorizing and desulfurizing station 16 and a slag discharging station 17 are arranged on the turntable at positions corresponding to the prescribed angle. A ladle 9 contg. received molten iron for a converter is set on a station 13 for lifting up or down charged molten iron to carry out desiliconization, dephosphorization, desulfurization and slag discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for pre-treating hot metal to be supplied to a steelmaking process.

(Prior art) In order to reduce manufacturing and refining costs of high-purity steel (low phosphorous, low sulfur steel), steel manufacturers have recently been using a method to reduce the production and refining costs of high-purity steel (low phosphorus and low sulfur steel), for example, between iron and steel converters. As shown in the proposal on page 1, desulfurization, dephosphorization, and desulfurization pretreatment refining are carried out from the blast furnace casthouse in the pig iron mixer car or in the hot metal ladle during transfer, and the hot metal is then sent to the converter, mainly for decarburization. Refining methods that only perform refining are becoming popular.

The typical method using a pig iron mixing car is explained below.

As shown in Fig. 4, the conventional method using a mixer car is to receive all of the hot metal from the blast furnace 1 through the tap runner 2 in the mixer car 3, and then move the mixer car to the desulfurization refining station 4, where it is discharged after desulfurization treatment. Slagyard 6
The pig iron mixer is moved to discharge the desulfurization slag into the slag pot 7. After that, the mixed pig iron car was moved to dephosphorization and desulfurization station 5,
After the dephosphorization and desulfurization treatment, the pig iron mixer truck is returned to the tailings field 6 again, and after the dephosphorization and desulfurization slag is slaged, it is transferred to the converter charging ladle 9 in the hot metal discharging pit 8 installed in the raw material building in the steelmaking factory 12. Then, the pretreated hot metal is discharged and transferred to the converter I via the conveyance lane 10.
NC is charged.

However, since a pig iron mixer car or a pot, which is a transport container between blast furnaces and converters, is used outside the converter factory, the process has the following disadvantages.

Originally, hot metal pretreatment and refining consists of two main refining reactions: desulfurization refining and dephosphorization and desulfurization refining. In order to efficiently carry out dephosphorization and desulfurization refining using hot metal, it is necessary to carry out the desulfurization treatment in advance to a level where the hot metal Si content 'e is 0.20% or less.

However, desulfurization slag generated by adding or injecting gaseous oxygen or solid oxygen sources (such as iron ore) during desulfurization has a main component of 5Io2, which is extremely inconvenient for the subsequent dephosphorization and desulfurization processing. For this reason (dephosphorization and desulfurization refining uses high basicity fluxing, and the reaction proceeds efficiently,
5i02 generated during desiliconization treatment must be slaged from the pig iron mixer or pan at the appropriate location after desiliconization treatment, which lowers the basicity of the flux and reduces efficiency.

In addition, after carrying out dephosphorization and desulfurization treatment, if the dephosphorization and desulfurization slag is not thoroughly discharged from the pig iron mixer car and pan, it may cause rephosphorization and resulfurization during converter refining. Not. The following problems arise from the above.

1) While the pig iron mixer car and pot are being moved to the slag dump after treatment, the surface layer of the slag in particular cools down, making it difficult to remove the slag, and a considerable amount of slag remains in the container after treatment. This will worsen the refining efficiency of the next step.

2) Since the container is moved between the pre-treatment smelting and the tailings field, the entire pre-treatment smelting time is extremely long, the temperature of the hot metal decreases, and there is no thermal margin in the converter. In other words, a problem has arisen in which the production capacity is reduced in that the scrap digesting capacity of the converter is reduced.

3) The hot metal temperature is considerably high (particularly for the dephosphorization reaction, since the hot metal is carried out in the container for transporting the hot metal between the blast furnaces and the converter, because it is carried out immediately after blast furnace tapping and before it is discharged into the converter charging ladle). In order to efficiently proceed with the dephosphorization reaction, since it progresses preferentially at lower temperatures,
Extremely inefficient.

4) It is necessary to change and move the pig iron mixing car or pot between the desiliconization treatment smelter, the dephosphorization and desulfurization treatment plant, and the tailings site every time each treatment is completed, and the actual operating rate of each facility is extremely low.

As mentioned above, the current hot metal pretreatment and refining method, which is carried out between blast furnace converters using a mixer car or a pot, has the following characteristics as a process to be implemented on an industrial scale: 1) efficiency, 2) heat loss, and 3) reaction optimization. There are many problems in terms of temperature selection and 4) equipment operating rate.

(Problems to be Solved by the Invention) The purpose of the present invention is to provide a method for easily solving the above-mentioned difficulties and achieving highly efficient hot metal pretreatment on an industrial scale. be.

(Means and effects for solving the problem) In order to solve the above problems and efficiently pre-process hot metal, the present invention rotates by repeatedly moving and stopping at predetermined angles on the same circumference. A turntable is provided, and a refining station is arranged at each of the predetermined angles, and when the hot metal contained in the container placed on the turntable is in the refining station, desulfurization, dephosphorization, desulfurization, and slag are performed. This is a highly efficient turntable type hot metal pretreatment and refining method characterized by performing one or more treatments.

After discharging the necessary hot metal for converter heat from the mixing car or ladle, which is a container for transferring hot metal between blast furnaces and converters, to the charging ladle, place the charging ladle on the turntable shown in Figure 1. The machine is moved by crane to the station, rotated by 720 degrees, for example,
At station (I), injection desulfurization is carried out using a solid oxygen source and gaseous acid, and the 81 content in the pig iron is desulfurized to below 0.20%, which allows efficient dephosphorization.

Then the table'! 1720 rotations, station (I
In F), the desulfurization slag is removed. Next, it is rotary dried for 72', and at station (III), powders of quicklime, fluorite, and a solid acid source are injected to carry out a dephosphorization and desulfurization reaction. Then, it rotates for an additional 720 revolutions, and dephosphorization is carried out at station (IV). Finally, it rotates 72 degrees and returns to the crane lifting position.

In this way, each function required for hot metal pre-smelting is placed at the desired position on the turntable, the pot is kept on standby at the station for a certain period of time, and the required refining work or preparatory work (slag removal, etc.) is performed on each of the functions. processed within a certain time at the station,
After that, each charging ladle is rotated at a certain angle and moved to the next station on the turntable, and at every intermittent stop time, the work required for hot metal pre-smelting is performed continuously in batches. To go.

In this case, the number of stations is determined by the hot metal components discharged into the converter charging ladle and the desired level of hot metal components after pretreatment. For example, hot metal S tapped from a blast furnace
When i % is 0.2% or less, which is extremely low for dephosphorization, the number of stations on the turntable is 3 stations: crane ω lowering, lowering station, dephosphorization/desulfurization station, and slag removal station. If the VC is normal, the rotation period of the turntable may be set to fl120'.

As mentioned above, by installing a turntable-type hot metal pre-smelting device in the raw material type in the converter factory and near the hot metal discharging bit, it is possible to compare the hot metal pre-treatment and refining method performed between the blast furnace converters described above. As a result, extremely excellent effects can be achieved in the following points in terms of the process.

1) 1st. In the figure, the desulfurization treatment time at station (I') is □ between rotations R of the turntable 720, and is several tens of seconds. In addition, the waiting time from the dephosphorization and desulfurization treatment at Station (I) to the dephosphorization and desulfurization slag discharge at Station (IV) is several tens of seconds, compared to the travel time to the slag disposal site using conventional methods. I was able to make it extremely short. Therefore, the slag can be removed at an extremely high temperature, and the fluidity of the slag is good, and the slag can be completely removed, making it possible to greatly improve the efficiency of each refining process.

FIG. 2 graphically shows the relationship between the residual slag (ky) in the desulfurization slag waste container and P (%) after hot metal dephosphorization.

In the figure, the treatment P was 0.1'O% and the temperature after treatment was 1320C.

2) The residence time of hot metal from blast furnace tapping to converter charging can be reduced by 60 minutes, resulting in a reduction in heat loss of 200 minutes.
00 K Cal/t.

3) Converter transfer hot metal ladle is a ladle that transfers the final hot metal between blast furnace converters, and a mixing car and a ladle between blast furnace converters! The temperature was about 40C lower than the temperature of the hot metal in the furnace, which made it possible to carry out the dephosphorization reaction efficiently.

FIG. 3 is a diagram showing the relationship between the temperature after dephosphorization treatment (U) and (P)%/[P)chi.

4) When performing preliminary treatment between blast furnace converters, there is a loss of time for changing the mixer truck and pot to the tailings field, so the actual operating rate of the desulfurization, dephosphorization, and desulfurization refining equipment is only 50% at most. However, in the turntable method, the operation only stops for several tens of seconds while rotating at a constant angle, and the actual operating rate is 95% or more.

At first glance, it seems possible to carry out hot metal pretreatment and refining by installing the hot metal discharged into the converter charging ladle in the converter factory raw materials building in the converter factory or on a trolley. In the treatment process, it is generally necessary to carry out all the refining and slag operations alternately, such as desiliconization smelting → desulfurization slag removal → dephosphorization and desulfurization smelting → dephosphorization and desulfurization slag removal. High operating rate, short-time processing was not possible because the equipment would be stopped and the handling time would increase due to the movement of the trolley.

Furthermore, if the converter charging ladle conveyor tray 12/ is used to move the charging ladle in such a process, there will be no time available for the actual charging of hot metal into the converter, and the industrial It cannot be implemented as a process on a large scale.

The present invention solves all of the above-mentioned problems extremely advantageously by installing a circular turntable-type hot metal pretreatment and scouring device in the raw material building and performing the smelting and slag operations at independent stations. I was able to solve it.

(Example) Example 1 of the present invention (an example of the apparatus used will be described with reference to FIG. 1).

All of the hot metal is received from the blast furnace 1 via the tap runner 2 in the mixer car 3, and the mixer car 3 is moved into the steelmaking factory 12, and the hot metal is transferred to the converter charging ladle 9 at the hot metal payout pit 8. After unloading, the charging pot 9 was placed on the transfer lane 10 at the charging pig iron raising station 13 on the turntable type pretreatment refining device 18.

After that, the desulfurization station 14, the tailings stillage 15, the dephosphorization/desulfurization station 16, the tailings station 17, the ω raising station 1'3, stop at each station at fixed time intervals, and the smelting at each station is stopped every 720 minutes.
carried out the work. When the charging ladle 9 after completion of treatment is lifted from the lifting station 13 and transported to the converter 1, the next processing ladle 9 is sequentially installed at the station 13.

(Example 1) The pig iron extracted from the blast furnace was 0, 13% Si, O, 3o% Mn.

Hot metal of 0.10 chips p.
After discharging 50 to the converter charging pot, 25 every 1200'
Rotates every minute.

In a turntable-type hot metal pretreatment refining device consisting of three stations, pretreatment was carried out according to the following procedure to obtain the target components of 0.03%Si, 0.25%Mn, and 0.0%.
Hot metal containing 20% P and 0.015% S could be obtained continuously.

First station: 250 was installed at the lane station for transporting the converter charging pot. (120,' rotations) 2nd station: Quicklime powder 15 kP / scale 2 Q ky / - pig iron, Fluorite powder 3 ky / - pig iron using all injection lances made by refractory field, hot metal with N2 gas It was blown into the tank for 20 minutes to carry out simultaneous dephosphorization and desulfurization.

(120' rotation) 3rd station: All the dephosphorization and desulfurization slag generated during the refining at the 2nd station was removed by a mechanical slag.

(120' rotation) 1st station: The material was picked up from the station on the transfer lane and charged into the converter.

(Example 2) 0.40%Si, 0.35%Mn tapped from a blast furnace.

0.11% P, 0.0.35% S, 3
After receiving 50% of pig iron into the mixed pig iron car, at the desulfurization field between the blast furnace and converter,
・Scale 17kf/pig and gas acid 2m",'
/ is injected into the molten pig iron of the pig iron mixing car using an injection lance, 0.08 To Si, 0.30
1Mn, 0.11%P.

Desulfurization was performed until it became 0.036% S.

At the hot metal discharging pit in the converter factory, 100 was discharged into the converter charging pot along with the hot metal and desulfurization slag in the pig iron mixing car, and 90
In a turntable hot metal pretreatment refining device consisting of four stations that rotate at 15-minute intervals, pretreatment was carried out according to the following procedure, and the target content of 0.02% Si was
, 0.28% Mn.

It was possible to continuously obtain a whole batch of hot metal with 0.015% P and 0.013% S1 temperature of 1330 iC.

1st station: 100 was used to transport the converter charging pot and set up the lane station.

(900 rotations) 2nd station: Desulfurization slag was removed using a vacuum slag machine.

(900 revolutions) 3rd station: 16 kg/pigment of quicklime powder,
One pig with a scale of 15 kP/, one pig with gaseous oxygen 1 m"/-, and one pig with 1 ky/' of fluorite.

Simultaneous dephosphorization and desulfurization was carried out by blowing 2 kg of CaCl2 powder into the pig iron for 10 minutes using a lance made of pig metal and refractories and using N2 gas as Chiaria. (900 rotations) Fourth station: The dephosphorization and desulfurization slag generated at the third station was removed by a mechanical scraper. (900 rotations) 1st station: The material was raised from the station and charged into the converter via the conveyance lane.

(Example 3) 0.60%Si, 0.40%Mn tapped from a blast furnace.

600% of hot metal of 0.012% S and 0.025% S was received in a pig iron mixing car and 340% of hot metal was delivered to the hot metal discharging pit in the converter factory.
After discharging the hot metal into the converter charging ladle, pretreatment is carried out according to the following procedure using a turntable-type hot metal pretreatment and scouring device consisting of five stations that rotate at 27-minute intervals every 720 seconds to obtain the desired composition of 0. .01%Si, 0.35
%Mn, 0.010%P, 01008%S, and a temperature of 13 ioc could be obtained continuously in a batch process.

1st station: 340 was installed at the lane station to transport the converter charging pot.

(720 revolutions) 2nd station: one pig of scale 21 kjE/, one pig of silver acid 3 m3/, quicklime powder 4 k/l - pig iron made of refractory 2
Scale and quicklime powder were injected from the tail of the heavy pipe lance with silver acid from the inner pipe and N2 gas from the outer pipe for 20 minutes to remove desiliconization and prepare the following components. (720 rotations) Si0.07chi.

Mn 0.33%, Po, 12%, SO, 026chi 3rd station: The desulfurization slag generated at the 2nd station is treated with a vacuum slag machine, and 20 ky/piece of iron is processed, and fluorite 2 ky/ After carrying out simultaneous dephosphorization and desulfurization treatment using a refractory lance using N2 gas as a carrier gas, subsequent desulfurization enhancement treatment was performed using soda ash injection at 3kp/l-pig, for a total of 20 minutes. injection was carried out. (Rotated 72 degrees) 5th station: The dephosphorization and desulfurization slag generated at the 4th station was removed by a full vacuum slag machine. (Rotated 72 degrees) 1st station: Loaded into the converter early on the transfer lane from the station.

In addition, the relationship between the amount of slag remaining in the container after desulfurization slag discharge (ky) and P (%) after hot metal dephosphorization at each implementation side number is shown in Figure 2.
Dephosphorization treatment temperature and CP)%/[P)% = Nislag smoked degree/
The relationship between the phosphorus concentration in the pig iron and the conventional example is shown in Figure 3.

As is clear from FIGS. 2 and 3, according to the method of the present invention, the amount of residual slag is less than 115 compared to the conventional example, the P% after dephosphorization is equal to that of water, and the temperature after dephosphorization is approximately It decreased by 100C, and (p)ql=/Cp]% improved by about 200.

(Effects of the Invention) As is clear from the above description, the present invention installs a table that rotates at a constant angle on the same circumference at a constant cycle in a raw materials building in a steelmaking factory, and A refining station is installed at the location of
Since the slag is removed, the treatment of the hot metal starts after it arrives at the steelmaking factory, and the temperature of the hot metal is as low as desired for dephosphorization, resulting in an improvement in the dephosphorization efficiency.
Figure) Since the slag removal can be carried out quickly and accurately, the slag removal can be completed when the slag has good fluidity, which greatly improves the smelting efficiency (Fig. 2), improving productivity, economy, and work efficiency. The effects brought about in the processing field are extremely large in terms of performance and operability.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the processing flow in the present invention, and Figure 2 compares the relationship between the amount of slag remaining in the container after desulfurization slag discharge and P (%) after hot metal dephosphorization in the present invention with that in the conventional method. Figure 3 is a diagram showing the relationship between hot metal temperature after dephosphorization treatment and (P)%/CP3% = phosphorus concentration in slag/phosphorus concentration in pig iron in the present invention, together with that of the conventional example, and Figure 4 is a diagram showing the relationship between hot metal temperature after dephosphorization treatment and (P)%/CP3% = phosphorus concentration in slag/phosphorus concentration in pig iron. It is an explanatory diagram of a processing flow of a conventional method by a car. 1: Blast furnace 3: Mixing car 8: Hot metal discharging pit 9: Charging pot 10: Transfer lane 1 Converter 12: Steel factory

Claims (1)

[Claims] A turntable that rotates by repeatedly moving and stopping at predetermined angles on the same circumference is provided, and a refining station is arranged at each predetermined angle, and hot metal contained in a container placed on the turntable is A high-efficiency turntable type hot metal pretreatment and refining method, characterized in that, when in the refining station, one or more of desiliconization, dephosphorization, desulfurization, and deslagination are performed.