JPS5811714A - Method for selecting and tapping molten steel and molten slag - Google Patents

Abstract

PURPOSE:To tap only a molten steel by preventing a molten slag from running off, by providing a tapping path curved in a plane which intersects the horizontal plane in a state of tapping posture, to a converter filled with both molten steel and slag, and balancing the static press. of the molten steel at the tail end of the molten-steel-flow against that of the molten slag following up the molten steel, with the aid of said path. CONSTITUTION:A curved tapping path 15 is provided continuously to connect it to a tapping hole 2 of a converter 1 curved in a plane which intersects the horizontal plane in a state of tapping flow posture, and a gas blow-in port 19 is provided to a curved part 18 locating nearest to the hole 2. When tapping is performed from the path 15, an inert gas is continuously blown into the path 15 from the port 19 before starting the tapping, and the gas is carried away to the downstream side of the path 15 to increase the tapping speed during the period from the starting of tapping to the end of it. At the end of tapping, the blowing gas is floated to the surface of the upstream side of the path 15 to lower the tapping speed thereby separating the molten steel and the molten slag.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating and tapping molten metal and molten slag, and in particular to a method for separating and tapping molten metal and molten slag, in particular, for reliably and quickly tapping only molten steel without reducing the yield of molten steel when tapping from a converter. It is something.

When the molten steel is discharged from the converter after blowing, slag is often mixed into the molten steel during the flow of the molten steel, especially at the final stage, and it is generally difficult to avoid this. Alloy materials added during or after molten steel, such as alloy iron chains, have the disadvantage of lowering the addition yield, damaging the refractories of the ladle, and furthermore having a negative impact on the quality of the steel during ingot making. There is a risk of causing

Therefore, in order to prevent molten slag from entering the ladle when tapping from the converter, various measures have been used, but none of these measures has been fully satisfactory. It was not possible.

For example, installing an opening/closing device such as a sliding gate at the tapping port to prevent molten slag from flowing out at the final stage of tapping eliminates the contamination of molten slag, but reduces the yield of molten steel, especially in large converters. Its maintenance and management is difficult.

Furthermore, the method of installing a slag get in a ladle and trapping the slag in the slug bot has the disadvantage of a large temperature drop.

For rough transportation, the use of a glue stopper ball and the so-called pot cutter, which removes the tapped steel from the ladle when tapping is complete, are used, but these methods are less reliable.

In order to solve these problems of the prior art, the inventors first focused on the difference in specific gravity of the slag with respect to the molten metal, and used static pressure at the trailing edge of the flow of the molten metal to prevent the flow of the molten slag that follows it. We developed a hot water tapping device that could do this and applied for a patent (Japanese Patent Application Laid-Open No. 33-9 Dada No. 30 (Patent Application No. 9-911))
).

The invention related to this patent application provides a converter in which molten metal or alloy is filled with floating slag covering the free surface of the converter, and is provided with a tapping passage that curves in a garden that intersects with a horizontal plane in the tapping attitude. The static pressure of the remaining molten metal after the molten steel flow discharged from this tapping passage is applied to the molten slag that follows the molten steel flow.
Together with the static pressure, this prevents the slag from flowing out.

The invention according to this prior application will be explained below based on illustrated examples.

Fig. 1 shows a partial cross section of the converter including the tapping port,
In the figure, 7 is the furnace body of the converter, C is the tapping port thereof, and J is a tapping device that can be removably attached to the tapping port.

As an example, the furnace body l is usually provided with a tapping loco on the shoulder of the furnace mouth so that it faces downward in the tapping position of the furnace body l. is a conductive brick, ≦ is a castable refractory, and 7 is an iron skin. The guiding brick I is made of square bricks with round holes stacked in layers from the corner t provided facing the tapping loco to the center of the tapping hole, and irregularly shaped bricks 41/ are placed around it to form the inner wall. Zhang] Brick and ginseng are closely connected.

In addition, here, a 7 flange t that opens outward at the tip of the tap hole λ is provided on the steel skin 7, and a bracket with a mounting edge n that occupies the same plane as the 7 flange 9 is provided. Attach it to the iron skin 7 at the empty position.

platen) // has a short oblique angular cylindrical iron skin part 12, inside which are hook-shaped combination bricks /3
is held in place by castable refractory material ν.

Then, a ring-shaped removable iron skin is screwed and fastened across the 7 langes 9 and the mounting edge 10, and a guide brick is placed inside it!
The deflection brick 11 which together with the deflection brick 13 forms a tapping passage /j having a channel-shaped longitudinal section is also held using a castable refractory material t'.

According to the tapping device for separating molten metal and molten slag according to this prior application, in the tapping position of the converter shown in FIG. It is clear that the hot water is dispensed into the ladle through the outlet passageway/1, which is not shown in the drawings.

In addition, at the end of tapping of this device, the static pressure of the remaining molten metal after the molten steel flow discharged from the tapping passage lj as described above is balanced with the static pressure of the molten slag flowing following this molten steel flow to prevent the molten slag from flowing out. The conditions for preventing this are expressed by the following equation (1) in Figure S2, which is a schematic and simplified version of Figure 1.

h2pm〉(h engineering + h,) door, -----(1
) here p! n! Molten steel density, pta I molten steel density, h,
is the height of the ascending passage of the tapping passage, ha ”m is the height of the descending passage of the hot water passage, hs + the thickness of the slag in the converter.

Therefore, in the invention of the prior application, the outflow of the molten slag n is prevented by constructing the tapping passage /j such that hl l hg satisfies the equation (1).

However, equation (1) is a conditional equation that only considers the static balance between molten steel and molten slag, and in reality, the molten metal flow has inertia, so if we take this into account, the molten steel and molten slag The conditions for complete separation and tapping of the slag are as shown in equation (2) below.

hg #m > (h engineering + h,) door, + α −−−−−(
Here α is the inertial force.

Therefore, in order to completely cut off the molten slag and tap only molten steel, it is necessary to remove the influence of the inertial force α by either increasing % h relatively or by reducing the molten metal flow velocity at the end of tapping. However, in actual operation, there are physical limitations such as the furnace body or its tilting limit, so it is difficult to increase h.

In this regard, the flow velocity can be reduced by reducing the flow path diameter on the molten metal inlet side of the tapping passage and increasing it in the middle, and by blowing inert gas into the inlet side passage of the tapping passage at the end of tapping. Attempts have been made, but with the former, it is extremely difficult to maintain the cross-sectional area of the outlet passage when considering the erosion of the bricks, and with the latter, it is difficult to detect when to reduce the flow velocity.
There was a serious problem in that the tapping time was extended compared to the case where a separate tapping device was not provided, and the temperature of the molten metal during tapping was lowered.

The present invention relates to a separate tapping method for advantageously solving these problems, and by lowering the tapping flow rate during the tapping phase, the tapping path is provided with conditions for reliable separation of molten metal and slag. By completely preventing slag outflow at the final stage and increasing the tapping speed,
The purpose is to shorten the overall tapping time and advantageously prevent a drop in molten steel temperature, and the structure is such that it is installed continuously to the tap port of the converter, and in its tapping position, in the plane that intersects with the horizontal plane. When dispensing hot water from a winding hot water supply passage, gas blowing (inert gas is continuously blown into the hot water supply passage at one point before the start of hot water dispensing) (inert gas is continuously blown into the hot water passage from the start of dispensing to the end of the dispensing process) In the final stage of tapping, the blown gas is forced to the upstream side of the tapping passage to reduce the tapping speed.

The present invention will be explained below based on illustrated examples.

No. Jv! J is a sectional view similar to FIG. 7 illustrating the apparatus used for carrying out the present invention, and the same parts as in FIG. 1 are designated by the same numbers. A gas blowing port 19 is provided at the curved part /l of the channel-shaped tapping passage /J that is closest to the tap opening.

This gas inlet/? Ha, the guiding brick! It opens in the direction opposite to the molten steel flow flowing inside, and the metal pipe X allows for example Nj! It is connected to a gas or other inert gas supply 11 (not shown).

Note that the position and direction of the gas inlet /9 are not limited to the illustrated example; MT drawn to the inner wall of the downward passage of /j,
Various changes can be made within the range enclosed by and. The reason will be explained later. Furthermore, the gas inlet 19 is provided with a buffspug, so that the intrusion of molten metal into the metal tube X can be effectively prevented.

When using the device configured in this way, first,
Continuous injection of inert gas into the tapping passageway/1 via the metal pipe X is started before the start of tapping, and then tapping is started based on the tilting of the furnace body l.

From the start of tapping to the * period, the flow rate of the tapping flow is high, so from the gas inlet n to the tapping path l! All of the gas bubbles blown into the tap flow along with the tap water passage /! The steel is flowed to the downstream side, and the buoyancy causes an increase in the speed of the tapped steel flow at the curved upward portion /ja.

That is, the gas bubbles increase the tapping speed. Note that the energy of the inert gas ejected in the direction opposite to the flow passing through the guiding brick j is extremely small compared to that of the tapping flow passing through the inlet 19, so that the energy exerted on the tapping flow is The effect can be ignored and therefore the conduction
The tapping flow passing through is not slowed down by the gas jet.

On the other hand, when the flow rate of the tapping stream decreases towards the end of the tapping stage, the inert gas bubbles are not swept away by the tapping stream but rise inside the guide tube, so the tapping stream is controlled by the buoyancy of the bubbles. It is decelerated due to flow resistance.

In other words, the position of the gas inlet 19 described above was selected to bring about such an effect on the molten metal, and this can be explained based on FIG. 1 by placing the gas inlet at position a.
When the buoyant force of the ejected gas always acts to reduce the tapping speed, the tapping time will be extended. In this case, the ejected gas flows to the downstream side of the tapping flow while the tapping speed is high, causing an increase in the tapping flow rate as described above, and conversely, the amount of remaining hot metal in the furnace decreases and the tapping flow rate decreases. After that, it floats toward the tapping port side and further reduces the tapping speed, so that the desired effect of the present invention is brought about.

A similar effect can be achieved by moving the gas inlet to position C (
This can be achieved by installing the device in any position up to MINT (equivalent to f) in Figure 3, and even if it is installed at position O, the ejected gas will flow through the tap flow as long as the tap speed is high. After the flow rate of the tapped metal decreases, it floats toward the tapping port.

Furthermore, if the gas inlet is installed at position w (1), the ejected gas will flow downstream as long as there is a flow of hot metal coming out, and if it is installed at position e, it will always flow downstream to increase the flow of hot metal coming out. Since it only increases speed, it cannot prevent the flow of slag.

Therefore, the gas inlet 19 provided at the appropriate position as described above.
By continuously blowing gas from the tap, the tapping speed is increased from the start to the end of tapping, and at the end of tapping when the remaining hot water is reduced, the speed is sufficiently effectively reduced to the extent that the inertial force can be ignored. will be done. Therefore, not only is the outflow of molten slag almost completely prevented, but even though the flow rate is low at the end of tapping, the overall tapping time is the same as when no separate tapping device is installed. It will be shortened.

In addition, the allowable setting range of the gas inlet 19 when the hot water tap passage /j is formed in a substantially U-shape in the length direction as shown in FIG. On the inside of the curve of the detour closest to the steel opening, it is the area surrounded by the tangent sT drawn to the inner wall of the lowest part of the tap passage /j and the normal H drawn to the point of contact.Furthermore, Even when the tap water path lj has a polygonal shape, the position of the gas inlet 19 can be determined in the same manner as described for Figure II#.

The required tapping time and the weight of slag flowing out according to the present invention will be explained below in comparison with the prior art.

FIG. 4.7 is a diagram showing the results of these comparisons, where white circles indicate the case where the present invention is implemented using the device shown in FIG. 3, and black circles indicate the case where the prior application device shown in FIG. 1 is applied. The X mark indicates the case where a separate hot water tapping device is not used.

FIG. 1 is a graph showing the required tapping time, and according to Gut 7, the tapping time according to the present invention is almost the same as when no separate tapping device is installed, regardless of the amount of molten metal, which is different from the earlier application. It is clear that when the amount of molten metal is trot, , and 2 sots, the time is reduced by about 1 minute compared to when such an apparatus is used.

Furthermore, FIG. 7 is a graph showing the weight of the slag flowing out. According to this graph, the weight of the flowing slag when this invention is applied is almost zero, as in the case of using the device according to the prior application. , it is clear that this value is considerably smaller than about t and 3t for the molten metal amount/lUt and kojO1, respectively, in the case where no separate tapping device is used.

Therefore, according to the present invention, it is possible to almost eliminate the influence of the inertial force in the above equation (2). If these conditions are met, complete slag separation and tapping can be achieved without reducing the yield or unnecessarily expanding the tapping equipment, and in addition, shortening the tapping time and effectively preventing a drop in molten steel temperature. be able to. Furthermore, complete separation of the slag can be achieved even if the amount of inert gas blown is kept constant throughout the tapping period, so the work can be simplified by omitting the operation to change the gas flow rate. .

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view showing a conventional device, Fig. 1 is an explanatory drawing showing the procedure for sizing, Fig. 3 is a sectional view similar to Fig. 1 illustrating the device used for carrying out the present invention, and Fig. FIG. 5 is an explanatory diagram showing the selection range of the gas inlet position, FIG. 5 is an explanatory diagram showing the gas inlet position in a modified example of the molten metal passage, and FIGS. L...Converter, K...Tapping port, J...Tapping device, G...Lining brick,! ...Direction brick, 6...Castable refractory, 7...Iron skin, /s...Tap passage, lto...Turning brick, n...Slag, /1...Detour Part, 19...Gas inlet 1. x...metal tube, 'rl
, 'r, , 'r, ・m-line, N knee...normal, a
. b f ' l d#...Position〇Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] L: When tapping hot water from the tapping passage that is connected to the tapping port of the converter and curves in a plane that intersects with the horizontal plane in the tapping position, a single gas inlet into the tapping passage is used before the tap starts. Inert gas is continuously blown in, and from the start of tapping to the end of tapping, the blown gas is forced downstream of the hot water tap path to increase the speed of hot water tap, while at the end of hot water taping, the blown gas is floated upstream of the hot water tap path. A method for separating molten metal and slag that reduces the tapping speed.