JP4765770B2 - Swirl suppression method, converter, and hot metal or steel manufacturing method - Google Patents

Description

The present invention relates to a method for suppressing eddy currents, a converter , and a method for producing hot metal or molten steel. Specifically, the present invention relates to a method for suppressing eddy currents formed from the vicinity of the discharge port to the molten metal bath surface when the molten metal flows out from the converter having the discharge port, the converter , and the hot metal or molten steel. It relates to the manufacturing method.

  When the molten metal is refined or cast, the molten metal is inevitably transferred to various molten metal containers. For example, in the iron making process, the molten iron transported to the steelmaking plant is charged into the hot metal pretreatment furnace or converter by various treatments, and the molten iron treated by each smelting container is accommodated from the outlet of the smelting container. It discharges to the ladle which is a container. In addition, the molten iron in the ladle further refined in the ladle is discharged from the outlet provided at the bottom of the ladle to the tundish, which is a molten metal container, and further provided at the bottom of the tundish. Discharge from the outlet to the mold.

  Generally, slag, which is an oxide having a lower density than the molten metal, floats on the molten metal accommodated in the molten metal container. This slag is often detrimental to processing in the next step. Therefore, when the molten metal is discharged and transferred to various molten metal containers, it is also important to separate the slag from the molten metal by discharging the molten metal but not discharging the slag.

  When the molten metal tries to flow out from the discharge port of the molten metal container, a vortex flow of the molten metal swirling in the circumferential direction of the outlet is formed from the vicinity of the discharge port to the molten metal bath surface. Because the slag floating on the molten metal bath surface is drawn to the molten metal side by this vortex, the slag cannot be sufficiently separated from the molten metal, and the slag flows out into the molten metal container that is transferred together with the molten metal. .

  Therefore, for example, in Patent Document 1, when the molten steel refined in the converter is discharged, the inert gas is supplied to the molten steel through a refractory plug provided with a heat-resistant steel tube provided at a position away from the outlet of the steel outlet. An invention has been disclosed in which the formation of a vortex of molten metal is inhibited by blowing into the metal.

Patent Document 2 discloses an invention that inhibits formation of a vortex of molten metal by providing a protrusion having the same shape at a position that is symmetrical with respect to the discharge port of the molten metal container. .
JP 2001-303122 A JP 2000-218362 A

  In the invention disclosed in Patent Document 1, since the refractory plug provided in the vicinity of the steel outlet is easily closed, it is difficult to stably inject the inert gas into the molten steel over a long period of time. For this reason, it is difficult to stably inhibit the formation of the molten metal vortex in the circumferential direction of the outlet for a long period of time, and it is stable for a long time that the slag floating on the molten metal bath surface is discharged together with the molten metal. Cannot be prevented.

  In addition, the invention disclosed in Patent Document 2 is originally less effective in inhibiting the formation of a vortex of molten metal. For this reason, it cannot prevent that the slag which floats on the bath surface of a molten metal discharges with a molten metal.

The present invention forms the hot metal or molten steel from the discharge port to the hot metal or molten steel bath surface when the hot metal or molten steel flows out from the discharge port without blowing inert gas into the hot metal or molten steel accommodated in the converter having the discharge port. is the, the hot metal or molten steel vortex swirling the circumferential direction of the discharge port, can be stably inhibited over a long period of time, preventing thereby, that the slag present on the molten iron or molten steel is discharged together with the molten iron or molten steel It is providing the method and converter which perform, and the manufacturing method of hot metal or molten steel using this method.

The present invention contains 5 mass% or more and 30 mass% or less of magnesia carbon at the peripheral position of the discharge port when the hot metal or molten steel accommodated in the converter is discharged from the discharge port provided in the converter. to move the center of the molten iron or molten steel vortex from the center of the outlet, and that the vortex, preferably provided only one rectifier unit order to Ru is changed in a recess like flow not generating slag Is a method for suppressing eddy currents. From another point of view, the present invention relates to a main body provided with a discharge port for discharging hot metal or molten steel to be accommodated, and only one magnesia carbon disposed at the peripheral position of the discharge port inside the main body. in together when the content mass% to 30 mass%, to move the center of the molten iron or molten steel vortex from the center of the discharge port, and rectification of the order to Ru is changed in a recess like flow not generating slag vortex And a converter.

Further, the present invention contains 5 mass% or more and 30 mass% or less of magnesia carbon at the peripheral position of the discharge port when the hot metal or molten steel accommodated in the converter is discharged from the discharge port provided in the converter. Then the Tomo, the ratio of the horizontal cross-sectional area S with respect to the horizontal cross-sectional area so of the discharge outlet (S / so) is 0.05 or more, to move the center of the molten iron or molten steel vortex from the center of the outlet, and, a method of suppressing vortex, characterized in that preferably provided a rectification portion of the order to Ru is changed in a recess like flow not generating slag vortex only one. From another point of view, the present invention relates to a main body provided with a discharge port for discharging hot metal or molten steel to be accommodated, and only one magnesia carbon disposed at the peripheral position of the discharge port inside the main body. in together when the content mass% to 30 mass%, the ratio of the horizontal cross-sectional area S with respect to the horizontal cross-sectional area So of the discharge outlet (S / So) is 0.05 or more, the outlet center of the molten iron or molten steel vortex center is moved from, and a converter, characterized in that it comprises a rectifier portion of the order to Ru is changed in a recess like flow not generating slag vortex.

  In order to make it possible to apply the present invention to, for example, a converter having a composition in which slag generated at a high environmental temperature is likely to cause melting damage, the “rectifying section” in the present invention contains magnesia carbon. The composition. The carbon content is desirably 5% by mass or more and 30% by mass or less. Thus, by periodically repairing the rectifying unit, the shape thereof can be stably maintained in a predetermined shape, for example, for a long period of 240 charges or more.

In these eddy current suppressing methods according to the present invention, it is desirable that the rectifying portion is a protruding portion formed in a protruding shape in order to improve the manufacturability.
From another aspect, the present invention is a hot metal or molten steel producing method characterized in that it comprises a step of performing the discharge of molten iron or molten steel from the converter using the method of suppressing vortex according to the present invention described above predicate is there.

The “rectifying unit” in these inventions refers to a unit that exhibits a rectifying action that inhibits the vortex flow of the molten metal in the circumferential direction of the discharge port. In the case where the rectifying portion is a protrusion formed in a protrusion shape, for example, the protrusion is provided so as to be orthogonal to or inclined with respect to the discharge port forming surface of the molten metal container. Moreover, when the horizontal cross-sectional area of a rectification | straightening part changes to a height direction, let the horizontal cross-sectional area S mentioned above be the maximum value among the horizontal cross-sectional areas of the rectification | straightening part which changes .

  According to the present invention, even when an inert gas is not blown into the molten metal accommodated in the molten metal container having the discharge port, when the molten metal flows out from the discharge port, the molten metal is discharged in the circumferential direction of the discharge port. The eddy current can be inhibited. For this reason, it is possible to significantly reduce the amount of slag that floats on the molten metal bath surface and is discharged along with the discharge from the discharge port of the molten metal.

(Embodiment 1)
The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. In the following description of the embodiments, the rectifying portion is a protrusion formed in a protrusion shape, the molten metal container is a converter, the molten metal is molten metal, and the eddy current suppression according to the present invention is suppressed. A case where molten steel is manufactured while including a step of discharging molten iron from the converter by applying the method will be taken as an example.

  First, the structure of the converter used in this embodiment will be described. The converter includes a main body provided with a discharge port at the bottom for discharging the hot metal to be accommodated, and a rectifying unit arranged at the inner periphery of the discharge port provided at the bottom of the main body.

  The structure and shape of each part of the main body of the converter and the shape and arrangement of the discharge port provided in the main body may be any well-known and conventional structure, and are not limited to specific ones. Since the structure of such a converter is well known to those skilled in the art, further explanation is omitted.

  The rectifying portion in the present embodiment is formed in a protruding shape as a protruding portion at a position which is the inner peripheral edge of the discharge port and is asymmetric with respect to the central axis of the discharge port. In the present embodiment, as shown in FIGS. 1A to 1C described later, the protrusions are formed in a quadrangular prism shape. The protrusions are for preventing the formation of a vortex of the hot metal in the circumferential direction of the discharge port by rectifying the hot metal.

  By providing a protrusion at the periphery of the discharge port, the vortex flow that entrains the slag that floats on the hot metal bath surface that is generated in the hot metal when the hot metal is discharged from the discharge port is changed to a hollow flow that does not involve this slag. This can prevent the outflow of the slag floating on the hot metal bath surface.

  There are suitable conditions for the arrangement, shape, and dimensions of the protrusions. If this condition is not satisfied, the effect of changing the hot metal flow into a hollow flow that does not involve slag is reduced. That is, as disclosed in Patent Document 2 described above, even if a plurality of protrusions having the same shape are provided at a position that is the periphery of the discharge port and is symmetric with respect to the central axis of the discharge port, the vortex flow that entrains the slag is generated. Although it can be slightly attenuated, the center is located immediately above the discharge port as in the case where no projection is provided, and a vortex that reaches the hot metal bath surface remains. For this reason, the remaining eddy current causes the slag floating on the hot metal bath surface to be drawn to the lower hot metal side, and the slag is discharged together with the hot metal.

  On the other hand, when the protrusion of the present embodiment is installed at the periphery of the discharge port at a position that is asymmetric with respect to the central axis of the discharge port, the center of the vortex that entrains the slag moves and decenters from just above the discharge port. However, it changes into a hollow flow that does not reach the bath surface of the hot metal. For this reason, even if this hollow flow exists, the slag floating on the hot metal bath surface is not drawn into the lower hot metal side.

FIG. 1 is an explanatory diagram showing the arrangement of the discharge ports 1 and the protrusions 2 provided in the container 3 used in the water model experiment conducted to confirm the action of the protrusions.
Based on the result of this water model experiment, the behavior of the vortex generated near the discharge port 1 when the container 3 is filled with water and the water is discharged from the discharge port 1 will be described. Note that oil or cork waste (cork waste in this embodiment) is mounted on the surface of the water stored in the container 3 to simulate the discharge behavior of slag.

When no protrusion is provided in the vicinity of the discharge port 1 (not shown), a vortex is generated in the water in the container 3 and the amount of cork waste discharged on the water surface in the container 3 is maximized.
As shown as arrangement A in FIG. 1A, even when the protrusion 2 is arranged on the periphery of the discharge port 1 at a position symmetrical to the central axis of the discharge port 1, the protrusion 2 is not provided. The amount of cork waste discharged cannot be reduced much compared to.

  On the other hand, as shown in the arrangement B shown in FIG. 1 (b) or the arrangement C shown in FIG. If it arrange | positions in the position which becomes, compared with the arrangement | positioning A shown to Fig.1 (a), the discharge | emission amount of a cork waste can be reduced significantly.

  The above results are shown in a graph in FIG. The simulated slag discharge amount (relative value) on the vertical axis of the graph of FIG. 2 is a relative value converted so that the value when the protrusion 2 is not disposed on the periphery of the discharge port 1 is 1.0.

  As shown in the graph of FIG. 2, even if two projecting portions 2 are arranged symmetrically as shown in the arrangement A of FIG. 1A, the simulated slag discharge amount is only slightly reduced, whereas FIG. By disposing the protrusions 2 as non-objects as in the arrangement B in b) or the arrangement C in FIG. 1C, the simulated slag discharge amount can be greatly reduced.

  In the arrangement A, the center of the formed vortex is coincident with the center of the discharge port 1 and the effect of suppressing the vortex is small. On the other hand, when the protrusions 2 are arranged asymmetrically as in the arrangement B or the arrangement C, the center of the vortex flows from the center of the discharge port 1 in either case of the arrangement B or the arrangement C, so that the vortex does not entrain the slag. It changes into a hollow flow.

  As described above, according to the present embodiment, the protrusion 2 is disposed asymmetrically around the periphery of the discharge port 1, so that the vortex formed along with the discharge from the discharge port 1 does not entrain the slag. The flow can be changed.

  Furthermore, the durability of the protrusion 2 was investigated by using a converter as the container 3 and changing the material of the protrusion 2 to be formed to silica, alumina, or magnesia carbon and discharging the hot metal. As a result, when the protrusion 2 is made of silica or alumina, the number of usable charges of the protrusion 2 is extremely low at 14 and 30 respectively. This is because the slag having a high FeO concentration present in the converter 3 causes the projections 2 to melt.

  On the other hand, when the composition of the protrusion 2 is magnesia, the reactivity with the converter slag is remarkably reduced, and the durability of the protrusion 2 is greatly improved to 140 charges. Furthermore, if the shape of the protrusion 2 is maintained as the initial shape by appropriately performing periodic repairs, the protrusion 2 has a durability of 240 charges or more. For this reason, the projection part 2 is made of magnesia which is a composition of a refractory. Desirably, it is magnesia carbonaceous.

The converter used in the present embodiment has the above structure. Next, the situation where the hot metal contained in the converter is discharged will be described.
In this Embodiment, the hot metal accommodated in a converter is discharged | emitted from the discharge port 1 provided in a converter. At this time, as a rectifying part for obstructing the flow of hot metal around the discharge port 1 at a position which is asymmetrical with respect to the central axis of the discharge port 1 at the peripheral edge of the discharge port 1, the projection 2 Is provided.

  For this reason, according to the present embodiment, an asymmetric flow is formed with respect to the peripheral edge of the discharge port 1 by the formed protrusion 2, and the vortex formed with the discharge of molten iron from the discharge port 1 is The slag can be changed to a hollow flow that does not involve the slag. For this reason, in the hot metal accommodated in the converter, a non-convoluted depression-like flow whose center is shifted from directly above the discharge port 1 is formed, so that the hot metal is discharged from the converter. Occurrence of vortex on the hot metal bath surface can be suppressed or eliminated. For this reason, it can suppress or eliminate that the slag which floats on the hot metal bath surface is discharged together with the hot metal.

  In this way, according to the present embodiment, even when the inert gas is not blown into the hot metal accommodated in the converter having the discharge port 1, when the hot metal flows out from the discharge port 1, The vortex of the molten metal in the circumferential direction can be inhibited. For this reason, it is possible to significantly reduce the amount of slag that floats on the molten metal bath surface and is discharged along with the discharge from the discharge port of the molten metal.

  If the method for suppressing eddy currents in this embodiment is applied to a converter for hot metal dephosphorization, it contains phosphorus that inevitably flows out together with hot metal when the hot metal after dephosphorization is discharged into the ladle. The amount of slag to be reduced can be reduced. For this reason, molten steel containing the slag discharged | emitted to a ladle after that is accommodated in the converter for hot metal decarburization, and molten steel can be manufactured, suppressing the amount of dephosphorization at the time of performing a decarburization process. Furthermore, when the molten steel decarburized in the converter for hot metal decarburization is discharged into the ladle, the amount of slag containing iron oxide that inevitably flows out along with the molten iron can be reduced. Highly clean steel with low [O] can be produced while suppressing the formation of alumina inclusions produced by the reaction of Al in the molten steel with this slag.

  Moreover, if this embodiment is applied to a converter, the molten iron remaining in the converter can be made extremely small when discharging molten iron from the converter, so that molten steel can be manufactured while increasing the iron yield. can do.

  On the other hand, if this embodiment is applied to a ladle, when discharging molten steel from the bottom of the ladle to the tundish in a continuous casting machine, the amount of slag containing iron oxide that inevitably flows out is reduced. Therefore, a highly clean steel with low [O] can be produced while suppressing the formation of alumina inclusions produced by the reaction between Al in molten steel and this slag in the tundish.

Furthermore, if this embodiment is applied to a ladle, the amount of molten steel remaining inside the ladle when discharging the molten steel from the ladle can be made extremely small, so that the molten steel can be added while increasing the iron yield. Can be manufactured.
(Embodiment 2)
Furthermore, Embodiment 2 will be described.

  In the first embodiment, the protrusion 2 is arranged on the periphery of the discharge port 1 at a position that is asymmetric with respect to the central axis of the discharge port 1, thereby suppressing the generation of vortex. On the other hand, as disclosed in Patent Document 2, when the protrusions 2 having the same shape are installed on the periphery of the discharge port 1 at positions symmetrical with respect to the central axis of the discharge port 1 (FIG. 1 described above) Even in the arrangement A) shown in a), there is further a critical value in which the ratio (S / So) of the horizontal cross-sectional area S of the protrusion 2 arranged on the periphery of the discharge port 1 to the opening area So of the discharge port 1 is present. When the optimization is performed as described above, the entrainment type vortex flow that entrains the slag changes into the non-entrainment type depression-like flow as in the first embodiment, and the same effect as in the first embodiment is obtained.

  When the protrusions 2 are arranged symmetrically, the center of the vortex or hollow flow does not move from directly above the center of the discharge port 1 and is not decentered from the center of the discharge port 1. However, even in this case, if the ratio (S / So) is greater than a certain critical value, the entrainment type eddy current that entrains the slag does not occur, and the bottom surface becomes a mortar shape and the non-entrainment type depression that does not entrain the slag. A flow is formed. If this ratio (S / So) is less than the critical value, the vortex is damped, but it does not become a non-convoluted hollow flow, but a thin vortex remaining in the form of a thread is formed, and the slag is sucked into the discharge port.

  By raising the ratio (S / So) to a certain critical value or more, the bottom surface becomes a mortar shape, and a non-convoluted depression-like flow that does not entrain slag can be formed. By installing at a position that is asymmetric with respect to the central axis of the discharge port 1, the center of the vortex or hollow flow can be moved and removed from directly above the discharge port 1 to form the above-described hollow flow. The effect to do can be further enhanced.

  The behavior of the vortex generated in the vicinity of the discharge port 1 when water is discharged from the discharge port 1 by changing the ratio (S / So) in various ways will be described. It should be noted that cork waste is placed on the upper surface of the water stored in the container 3 to simulate the slag discharge behavior.

  As a result, when the ratio (S / So) is smaller than the critical value, vortex flow is generated and the discharge amount of cork waste floating on the water surface in the container 3 increases. However, when the ratio (S / So) is equal to or greater than the critical angle, the amount of cork waste discharged is reduced, and the generation of eddy currents can be suppressed. Further, when compared with the same ratio (S / So), the arrangements B and C at the asymmetric positions shown in FIG. 1B or FIG. 1C are more symmetrical than those shown in FIG. The amount of cork waste discharged is lower than the position A at the position. FIG. 2 is a graph showing the relationship between the ratio (S / So) and the simulated slag discharge amount (relative value).

  As shown by the graph in FIG. 2, the ratio (S) regardless of whether the protrusions 2 are arranged on the periphery of the discharge port 1 at positions that are symmetric or asymmetric with respect to the central axis of the discharge port 1. If the ratio (S / So) is 0.05 or more, the simulated slag discharge amount can be greatly reduced. it can.

As shown in the graph of FIG. 2, the more preferable range of the ratio (S / So) is 0.07 or more, and more preferably 0.1 or more.
Furthermore, the arrangement B shown in FIG. 1 (b) or the arrangement C shown in FIG. 1 (c) both significantly suppress the slag discharge amount than the arrangement A shown in FIG. 1 (a). it can.

  In the arrangement A, the center of the vortex flow coincides with the center of the discharge port, whereas in the arrangements B and C, the center of the vortex flow moves from the center of the discharge port 1 and the vortex flow formed thereby further increases the momentum of the vortex flow. Reduced.

  Thus, in the present embodiment, the main body provided with a discharge port for discharging the hot metal to be accommodated, and the peripheral edge of the discharge port inside the main body, which is symmetrical or asymmetric with respect to the central axis of the discharge port The ratio of the horizontal cross-sectional area S to the horizontal cross-sectional area So of the discharge port (S / So) is 0.05 or more and is a rectifying unit for inhibiting the flow of hot metal in the circumferential direction of the discharge port A converter equipped with is used.

  And in this Embodiment, when discharging the hot metal accommodated in this converter from the discharge port provided in the converter, it is the periphery of the discharge port and is symmetrical or asymmetric with respect to the central axis of the discharge port. At a position where the ratio of the horizontal cross-sectional area S to the horizontal cross-sectional area So of the discharge port (S / So) is 0.05 or more, and a protrusion for inhibiting the flow of hot metal in the circumferential direction of the discharge port is provided This prevents the generation of vortex flow.

  According to the present embodiment, since the ratio (S / So) of the horizontal cross-sectional area S of the rectifying unit to the horizontal cross-sectional area So of the discharge port is set to 0.05 or more, it is the same as the position that is symmetric with respect to the discharge port. Even if the rectifying portion having the shape of is provided, a hollow flow that does not involve the slag can be formed in the molten metal instead of the vortex that entrains the slag.

  That is, when the rectifying unit is arranged at a position that is symmetric with respect to the discharge port, the center of the vortex or hollow flow formed in the molten metal at the time of discharge does not move from directly above the center of the discharge port and Located in. However, in this embodiment, since the ratio (S / So) is set to 0.05 or more, a vortex flow that entrains the slag does not occur, and the bottom of the vortex flow forms a hollow flow that does not entrain the slag. it can. When the ratio (S / So) is set to less than 0.05, the bottom surface of the vortex is not mortar-shaped, and a vortex with a thread-like bottom is sucked into the discharge port. In the present embodiment, in particular, by installing the rectification unit asymmetrically with respect to the discharge port, the vortex or hollow flow is moved so that the center is shifted from directly above the discharge port, and the ratio (S / So) is increased. Since it can be 0.05 or more, the vortex | eddy_current which entrains slag does not generate | occur | produce, but the bottom face becomes a mortar shape and can form the hollow flow which does not entrain slag.

  As described above, according to the second embodiment, when the hot metal flows out from the discharge port 1 without blowing the inert gas into the hot metal accommodated in the converter having the discharge port 1, The hot metal swirl in the direction can be inhibited.

  In the first and second embodiments, it is preferable to change the horizontal sectional area of the rectifying unit in the height direction. Specifically, it is desirable to make the horizontal cross-sectional area of the lower part larger than the upper part of the rectifying part (projection part). This is because the so-called “inclined” shape in which the horizontal cross-sectional area increases downward is provided on the side surface of the protruding portion, so that the effect of decentering the vortex or hollow flow from directly above the discharge port can be promoted. The degree of “tilt” provided is preferably 20 ° or more, more preferably 40 ° or more, with respect to the vertical direction.

The present invention will be described more specifically with reference to examples. In the following, “%” regarding the composition indicates “mass%”.
(Conventional example)
The hot metal, which has been desulfurized in advance as needed, is charged into an upper bottom blown converter type molten metal container, which is a 250-ton scale dephosphorization furnace, and dephosphorized until [P] becomes 0.01%. The dephosphorizing hot metal (C: 3.9%, Si: 0.003%, Mn: 0.2%, P: 0.01%, S: 40 ppm) at an end point temperature of 1320 ° C. It discharged to the ladle through the discharge port.

  This hot metal and the dephosphorization slag that inevitably flows out when the hot metal was discharged were charged into an upper bottom blown converter type molten metal container, which was a decarburization furnace, and decarburized. In the decarburization furnace, slag having low dephosphorization ability was used. The molten steel composition after decarburization was (C: 0.05%, Si: trace, Mn: 0.15%, P: 0.02%, S: 40 ppm).

[P] from after dephosphorization to after decarburization has increased from 0.01% to 0.02%. This is because slag with high phosphorus concentration is discharged from the dephosphorization furnace to the ladle. This is because a large amount of spilled.
(Example of the present invention)
As shown in FIG. 1 (a) or FIG. 1 (b), magnesia carbon having a carbon content of 5 to 30% by mass at the discharge port 1 of the above-mentioned top-bottom converter type molten metal container which is a dephosphorization furnace. The protrusions 2 made of quality were arranged so as to have the ratio (S / So) shown in Table 1, and the same processing as described above was performed. The [P] concentration after dephosphorization was 0.01%. On the other hand, the [P] concentration after decarburization is summarized in Table 1.

  From Table 1, No. whose ratio (S / So) is less than 0.05. In 1, the amount of slag flow after dephosphorization was large, and the amount of rebound was large. On the other hand, No. with a ratio (S / So) of 0.05 or more. In 2 and 3, the amount of slag outflow was small and the amount of reverse phosphorus was small. In addition, the protrusion 2 is disposed at a position that is asymmetrical with respect to the central axis of the discharge port 1 at the periphery of the discharge port 1. In Nos. 4 to 6, the ratio (S / So) values are the same. It can be seen that the amount of reverse phosphorus can be further suppressed with respect to 1-3.

  From the above results, by optimizing the horizontal cross-sectional area of the protrusion 2 installed at the periphery of the discharge port 1, the outflow amount of slag can be suppressed, and the protrusion 2 is discharged to the periphery of the discharge port 1. By arranging it at a position that is asymmetric with respect to the central axis of the outlet 1, the effect of suppressing the outflow amount of the slag can be further enhanced.

  In addition, the silicic projection part 2 was arrange | positioned in the discharge port of this dephosphorization furnace, and the continuous test was done. When the material of the protrusion 2 is magnesia carbon, it was possible to maintain the effect of reducing the increase in phosphorus concentration until 240 charges after installation, whereas the material of the protrusion 2 was siliceous. In some cases, only 14 charges were sustained after installation. The cause of this is considered to be that when the inside of the dephosphorization furnace was observed during non-treatment, when the siliceous material was used, the volume of the protrusion was significantly reduced due to melting damage.

  The molten steel in the decarburization furnace obtained by the example of the present invention in Example 1 described above was discharged to the ladle through the discharge port of the decarburization furnace. At that time, as shown in FIG. 1 (a) and FIG. 1 (c), a magnesia carbonaceous protrusion having a carbon content of 5 to 30% is disposed or disposed in the vicinity of the discharge port of the decarburization furnace. Without experimenting.

  The molten steel accommodated in the ladle by these methods was subjected to normal secondary refining treatment (circulation time at RH 15 minutes). A sample was taken from the molten steel in the ladle after the secondary refining, and [O] analysis was performed. The [O] concentration reflects the amount of inclusions in the steel, and the lower the [O] concentration, the higher the cleanliness. Moreover, the [O] density | concentration after secondary refining in the case where a protrusion part is not provided was 25 ppm. Table 2 shows the results when the protrusions are provided. In addition, the inclination angle of the side surface of the protrusion was set to 25 degrees so that the horizontal cross-sectional area below the protrusion was larger than above.

  From Table 2, when the ratio (S / So) is smaller than 0.05, the slag outflow is not sufficiently suppressed, and [O] after secondary refining shows a high value, whereas the ratio (S / So) Is 0.05 or more, the [O] concentration is significantly reduced.

  As shown in Table 2, when the arrangement of the protrusions is changed from the arrangement A (No. 7 to 9) to the arrangement C (No. 10 to 12), the outflow of the slag can be further suppressed. It can be seen that the concentration decreases.

  From the above, by optimizing the horizontal cross-sectional area of the protrusions installed at the periphery of the converter outlet, the outflow of the converter slag containing iron oxide can be suppressed, and clean steel is melted. be able to. Furthermore, the effect of suppressing the outflow of the converter slag can be further enhanced by disposing the protrusions asymmetrically with respect to the central axis of the discharge port at the periphery of the discharge port.

It is explanatory drawing which shows arrangement | positioning with the discharge port of a container used for the water model experiment performed in order to confirm the effect | action of a projection part, and a projection part. It is a graph which shows the relationship between ratio (S / So) and simulation slag discharge | emission amount (relative value).

Explanation of symbols

1 Discharge port 2 Protruding part (rectifying part)
3 Molten metal container

Claims (6)

The molten iron or molten steel accommodated in the converter, when discharged from the discharge port provided in said transfer furnace, the peripheral position of the exhaust outlet, to together to contain 30 mass% or less than 5 wt% magnesia carbon, soluble the center of the pig iron or molten steel vortex of moving from the center of the exhaust outlet, and characterized in that preferably provided a rectification portion of the order to Ru is changed in a recess like flow not generating slag the vortex only one The eddy current suppression method. When the hot metal or molten steel accommodated in the converter is discharged from the discharge port provided in the converter, magnesia carbon is contained at 5% by mass to 30% by mass at the peripheral position of the discharge port and the discharge port the ratio of the horizontal cross-sectional area to the horizontal cross sectional area (so) of (S) (S / so) is 0.05 or more, to move the center of the molten iron or molten steel vortex from the center of the discharge port, and the method for suppressing vortex, characterized in that preferably provided a rectification portion of the order to Ru is changed in a recess like flow not generating slag vortex only one.   The method for suppressing eddy currents according to claim 1, wherein the rectifying portion is a protruding portion formed in a protruding shape. A main body provided with a discharge port for discharging hot metal or molten steel to be accommodated, and only one magnesia carbon disposed in a peripheral position of the discharge port inside the main body, containing 5 mass% or more and 30 mass% or less. together to move the center of the molten iron or molten steel vortex from the center of the discharge port, and a; and a rectifying portion of the order to Ru is changed in a recess like flow not generating slag the vortex Converter. A main body provided with a discharge port for discharging hot metal or molten steel to be accommodated, and only one magnesia carbon disposed in a peripheral position of the discharge port inside the main body, containing 5 mass% or more and 30 mass% or less. the ratio of the horizontal cross-sectional area to the horizontal cross-sectional area of the exhaust outlet (so) with (S) (S / so) is 0.05 or more, to move the center of the molten iron or molten steel vortex from the center of the discharge port and, converter, characterized in that it comprises a rectifier portion of the order to Ru is changed in a recess like flow not generating slag the vortex.   Manufacturing of hot metal or molten steel, comprising a step of discharging the molten iron or molten steel from the converter using the eddy current suppressing method according to any one of claims 1 to 3. Method.

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