JPH02225614A - Converter steel tapping equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a converter tapping device for tapping molten steel into a ladle after converter blowing.

[Prior Art] In steel factories, integrated production is performed from the converter process to the casting process. That is, the molten steel from the converter is tapped into a large ladle, refined in, for example, an RH degassing facility 61, and finally cast in a casting facility. In the converter process, when the molten steel reaches a predetermined composition and temperature, blowing is completed, and the entire converter is gradually tilted, and the steel is tapped into a large ladle through a tap in the upper side wall of the furnace. When tapping, only molten steel flows out to prevent slag from flowing out as much as possible, thereby preventing slag from entering the ladle.

The tapping port is formed to have a small diameter compared to the furnace body capacity to prevent slag from flowing out together with molten steel.

When tapping is to be stopped, the tilted converter is returned to an upright position and the slag remains in the furnace.

Conventional tapping equipment transfers molten steel from a converter to a ladle in the atmosphere.

[Problems to be solved by Ming] However, in the conventional converter tapping method, the converter side and the ladle side are exposed to the outside air, so the tapped molten steel with a deoxidizer added is exposed to the atmosphere. The nitrogen contained therein was picked up, increasing the [N] concentration in the molten steel, making it impossible to produce low-nitrogen steel from converter molten steel that had already been deoxidized. For this reason, when producing low nitrogen steel, converter molten steel must be in an undeoxidized B state (in the undeoxidized state, oxygen in the steel is a surface active element, so even if the steel is tapped in the atmosphere, the [N] of the molten steel is does not rise. ), and the molten steel must be deoxidized in subsequent stages such as RH degassing and LF refining, increasing processing costs.

Furthermore, in tapping under atmospheric conditions, atmospheric oxygen is involved in the tapped molten steel, and the deoxidizing agent in the molten steel is consumed, resulting in an increase in the deoxidizing agent consumption rate.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a converter tapping device that can effectively prevent oxidation of molten steel and nitrogen gas pickup during tapping.

[Means for Solving the Problems] A converter tapping device according to the present invention includes a means for tilting the converter around a horizontal axis, and a first guide member provided so as to surround the converter tap opening. a second guide member that surrounds the molten steel inlet of the molten steel container and is provided so as to be in sliding contact with the first guide member when the converter is tilted to block the falling area of the molten steel from the outside air; and gas blowing means for blowing at least one of inert gas, carbon dioxide gas, and carbon monoxide gas into the falling area at a flow rate of 10,100 N or more per hour.

The reason why the blowing gas flow rate is set to 10100N or more per hour is as follows.
This is because if the gas flow rate is less than 1008 m'/hour, the amount of outside air entering will exceed this, making it difficult to maintain the molten steel falling area in a non-oxidizing atmosphere.

In this case, it is preferable to provide a stopper member for blocking the molten steel flow path of the tapping port, and to blow gas from this stopper member.

[Function] In the converter tapping apparatus according to the present invention, first and second guide members are provided around each of the tap port on the converter side and the injection port on the molten steel container side, and when the furnace is tilted, the second guide member is provided. By sliding the first guide member along the guide member, the molten steel passages of the tapping port and the injection port can be aligned with the container in a sealed state, and the tightness of the connecting portion is high, and the taping There is virtually no entry of outside air into the area where the molten steel falls. Furthermore, since at least one of inert gas, carbon dioxide gas, and carbon monoxide gas is blown into this sealed area, oxidation of the tapped molten steel and nitrogen pickup are effectively prevented.

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

1 and 2 are vertical sectional views schematically showing a part of a converter and a ladle equipped with a converter tapping apparatus according to an embodiment of the present invention. The converter 10 is covered with an iron shell 11, and the inside thereof is lined with a refractory 12. Moreover, the converter 10 is
It is supported by a tilting device (not shown). A trunnion ring (not shown) on the outer periphery of the furnace body is connected to a rotating shaft of a tilting device, so that the converter 10 can tilt 360'.

A tapping port 14 is provided on the upper side wall of the converter 10, and when the furnace body is tilted, the molten steel in the converter flows through the molten steel passage 16 of the tapping port 14.
is starting to flow out. In addition, converter melting #118
is covered with a slag 19 of a predetermined thickness.

On the other hand, a ladle 2 is disposed below the converter installation hN to receive tapped molten steel. The ladle 2 is placed on a truck (not shown), and when molten steel is charged, the ladle 2 is transported from the converter equipment to the casting equipment. A lid 3 for preventing oxidation of the molten metal is placed over the opening of the ladle 2. A cylindrical member 4 stands upright in the center of the lid 3, and the member 4 forms a passage for falling molten steel. A thin flange 5 (second guide member) having a predetermined shape is provided so as to surround the upper end of this member 4. Further, a gas pipe 6 is attached to a part of M3, and carbon dioxide gas is blown into the ladle 2 through the gas pipe 6.

The seal flange 15 (first guide member) is connected to the converter tap port 1.
It is provided so as to surround 4. Seal flange 15
is made by press-forming a steel plate to match the trajectory of the tip of the tap hole when the converter is tilted, and its outer surface is coated with refractory material. Seal flange 5 on ladle side
It also has the same shape as the seal flange 15 on the tapping port side,
For example, the seal flange 15 comes into sliding contact with the seal flange 5 when the converter tilt angle is in the range of 75 to 1.05'. In addition, in this case, both seal flanges 5.15
By further increasing the size of the converter, the tilting angle of the converter can be increased from 30 to 100 liters.
It is possible to make sliding contact between the two within a range of 10°.

As shown in FIGS. 3 and 4, before tapping, a cap-shaped stopper 30 is inserted into the molten steel flow path 1 of the tapping port 14.
It is pressed so as to block the exit of No. 6. Stopper 30
is opened and closed by a drive device protected by an iron case 21 as shown. This iron case 2
1 is fixed to the steel shell 11 near the tapping port 14, and a cylinder 24 and the like are housed inside it. That is, the cylinder 24 is connected to the shaft 23. It is swingably supported within the case 21 via the bracket 22, and furthermore, the rod 2 of the cylinder 24 is
5 is connected to an arm 29 via a shaft 26. The base ends of the two arms are supported by the case 2 via the shaft 28° bracket 27, and the stopper 30 at the tip is supported by the case 2 through the bracket 27.
It rotates around 8.

As shown in FIGS. 5 and 6, a gas passage '32 is formed to open at the tip of the stopper 30. As shown in FIGS. This gas passage 32 is connected to a gas supply device (not shown) that controls the flow rate control valve via the gas pipe 31 of the arm 29, and a predetermined flow rate of argon gas or CO2 gas is supplied from the gas supply device. It is now possible to do so.

Next, a case will be described in which the above-mentioned apparatus is used to tap molten steel into a ladle in a converter.

As shown in FIG. 2, when the furnace body is tilted toward the tapping port 14 with the passage 16 blocked by the stopper 30 after the completion of blowing, the seal flange 15 is attached to the seal flange 5 on the ladle side. The tapping port 14 is guided so as to communicate with the molten steel inlet of the ladle. When the tilting angle of the furnace body reaches approximately 809, the tilting is stopped and the rod 25 is retracted into the cylinder 24. As a result, the stopper 30
rotates around the shaft 27 and is pulled away from the opening of the molten steel passage 16 at the tapping port, and the converter-like molten steel 18 falls through the passage 16 into the ladle 2.

As shown in FIG. 1, during tapping, a predetermined flow rate of CO2 gas is supplied to the stopper 30 and the gas pipe 6, and the molten n41
The falling area of No. 8 is made into a non-oxidizing atmosphere. When a predetermined amount of molten steel is contained in the ladle 2, the stopper 30 is rotated,
The passage 16 is closed and tapping is stopped.

In Figure 7, the horizontal axis shows the timing of aluminum injection (a parameter value expressing the timing of metal aluminum injection), and the vertical axis shows the amount of nitrogen pick-up in molten steel. It is a graph diagram investigated about. In the figure, the white circles indicate the results using a conventional steel tapping device.
The black circles represent the results obtained using the converter tapping apparatus according to the embodiment of the present invention. As is clear from the figure, according to the converter tapping apparatus according to the embodiment of the present invention, there is almost no nitrogen pickup even when deoxidized steel is drawn, and even in the case of low nitrogen steel, deoxidized steel is extracted. It has become possible. Furthermore, entrainment of oxygen during steel tapping was eliminated, and the basic unit of deoxidizing agent for metal aluminum etc. could be significantly reduced.

FIG. 8 is a graph showing the relationship between the converter-side sealing gas flow rate on the horizontal axis and the nitrogen pick-up amount on the vertical axis. Table 1 also shows the conditions for each of the results indicated by black circles in FIG. As is clear from the figure, as the seal girth flow rate increases, the nitrogen pick-up amount stabilizes at a low level. In this case, regardless of the steel type, if the sealing gas flow rate on the converter side is set to 10,100 N/hour or more, the maximum allowable value for low nitrogen steel is 25 ppp.
I was able to clear m.

': Figure 39 is a graph showing the relationship between the two under various conditions, with the horizontal axis representing the amount of aluminum consumed per ton of molten steel and the vertical axis representing the temperature change of the tapped molten steel. . In the figure, black circles represent the results of steel tapping using the steel tapping device of the present application, and white circles represent the results of steel tapping using the conventional steel tapping device. As is clear from the figure, the temperature drop in non-oxidized steel tapping using the steel tapping device of the present application is lower and more stable than in normal steel tapping using the conventional steel tapping device.
It was possible to lower the exit M temperature by about 5°C compared to the conventional method.

This is thought to be due to the fact that in the case of the present invention, the steel is tapped in an airtight container sealed by a sealing flange, so it is possible to reduce heat loss from the tapped flow caused by convection. .

According to the Niki Example, the nitrogen pick-up amount of the tapped molten steel could be made less than 25 ppm regardless of the steel type.

Furthermore, according to the above embodiment, the inside of the ladle is not replaced with an inert gas or the like beforehand, and the sealing gas is supplied to the molten steel falling area almost at the same time as the start of tapping, so that the molten steel can be We were able to suppress the amount of nitrogen pick-up to below the target value.

[Effects of the Invention] According to the present invention, the sealing performance of the tapping port is improved, and oxidation of tapped molten steel and nitrogen pickup can be effectively prevented. Therefore, it is possible to produce low-nitrogen steel from already deoxidized converter molten steel, the deoxidation treatment of molten steel in the subsequent process can be reduced, and the processing cost can be significantly reduced.

Furthermore, it is possible to set the output #A temperature low, which is economical.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views schematically showing a part of a converter and a ladle equipped with a converter tapping device according to an embodiment of the present invention, and FIG. 3 is a longitudinal sectional view of a converter tap opening. 4 is a partially cutaway plan view showing the vicinity of the tapping port, FIG. 5 is a front view of the stopper, FIG. 6 is a side view of the stopper, and FIGS. 7 to 9 Each figure is a graph diagram for explaining the effects of the embodiments of the present application. 2; Ladle, 5, 15; Seal flange, 6゜31; Gas pipe, 10; Converter, 14; Tap hole, 16; Molten steel flow path, 1
8; Molten steel, 19; Slag, 24; Cylinder, 30; Stopper, 32; Gas passage

Claims (3)

[Claims] (1) A means for tilting the converter around a horizontal axis, a first guide member provided so as to surround the converter tap opening, and a means for surrounding the molten steel inlet of the molten steel container, which A second guide member is provided so as to be in sliding contact with the first guide member to isolate the molten steel falling area from the outside air, and an inert gas, carbon dioxide gas, and carbon monoxide gas is provided in the molten steel falling area. 1. A converter tapping device comprising: gas blowing means for blowing at least one of the above gases at a flow rate of 100 Nm^3 or more per hour. (2) The converter tapping apparatus according to claim 1, further comprising a stopper member for closing the molten steel flow path of the tapping port. (3) The converter tapping apparatus according to claim 2, wherein the stopper member has gas blowing means.