KR20180056759A - A method for introducing an additive material for molten metal, and a method for introducing an additive material for molten metal - Google Patents

Abstract

1. A method for introducing an additive into a container containing molten metal, the method comprising: a nozzle disposing step of disposing a nozzle above molten metal contained in the container; and an additive material transporting step of transporting the additive into the nozzle by a carrier gas, Wherein an area of the injection port is larger than an area of the introduction port in the nozzle. By this injection method, it is possible to supply the additive material uniformly to the surface of the molten metal contained in the container, and to achieve both the sufficient addition effect by the additive material and the reduction of the additive material usage amount.

Description

A method for introducing an additive material for molten metal, and a method for introducing an additive material for molten metal

TECHNICAL FIELD The present invention relates to a method for introducing an additive such as a heat insulating material into a container containing molten metal such as molten steel in a process of manufacturing a metal, for example, steelmaking, To an additive material input method for injecting an additive material into a container using a nozzle, and to an additive material input device.

A molten iron produced in a furnace is subjected to decarburization treatment and heat treatment using an electric furnace after suitable preliminary treatment is performed, resulting in molten steel at about 1600 ° C. The molten steel is subjected to component adjustment and degassing using a secondary refining facility. The molten steel that has undergone this steelmaking process is solidified using a continuous casting machine, and is made into slabs of steel such as slabs, blooms, and billets.

At that time, molten steel passing through a treatment process by a converter (hereinafter referred to as a " transfer process ") is transported and processed in the order of a secondary refining facility and a continuous casting machine in a state of being housed in a container such as a ladle. The molten steel supplied to the continuous casting machine needs to have an appropriate temperature higher than the solidification temperature. However, after the conversion process is performed, the temperature of the molten steel in the container decreases due to heat radiation. When the temperature of the molten steel is lowered to a temperature lower than the predetermined temperature, the oxidized element is added during the secondary refining in accordance with the lowered temperature range to increase the temperature of the molten steel by the oxidation heat of the oxidized element have.

However, when the temperature raising treatment is performed, the operating time of the secondary refining increases. Further, by performing the temperature raising treatment, oxides originating from the oxidized element are generated, and the amount of the oxide in the molten steel is increased. In this case, the nozzle for supplying the molten steel to the continuous casting machine is likely to be clogged, resulting in lower productivity, and the quality of the cast steel obtained by continuous casting of such molten steel is lowered. Therefore, it is preferable not to carry out the temperature raising treatment at the time of secondary refining.

It is also conceivable to increase the temperature rise width in the converter process and to increase the temperature of the lubrication from the converter in place of the temperature raising process at the time of secondary refining. In this case, however, the productivity in the conversion process is reduced, and the thermal load applied to the converter installation becomes excessive. For this reason, there is a limitation in increasing the tapping temperature.

Therefore, it is necessary to suppress the lowering of the molten steel temperature due to the heat radiation in the process from the conversion step to the start of the continuous casting. As a method for effectively suppressing the lowering of the molten steel temperature, there is a method of putting a heat insulating material (a molten steel insulating material) into a container containing molten steel. The insulating material has the form of aggregates of particles, and the diameter of each particle is, for example, several millimeters. The following characteristics are required for the insulating material.

(1) The density shall be smaller than that of molten steel.

(2) Do not react negatively on molten steel.

(3) By covering the surface of the molten steel, it should be possible to suppress heat radiation from the molten steel to the atmosphere.

In order to obtain the characteristics (3), it is preferable that the heat insulating material is dispersed on the molten steel surface without aggregation. Specific examples of the material that can be used as a heat insulating material include vermiculite (obtained by heating vermiculite, gono vermiculite or the like), burned rice (burnt rice husk), and the like.

It is preferable that the heat insulating material is supplied to the entire surface of the molten steel. As a concrete example of the method of inserting the insulating material, there is a method of dividing and inserting all the insulating materials to be charged into a plurality of input units so as to be an amount of about 10 kg or less. In this case, the heat insulating material is filled in a small pouch per unit of the unit, and is inserted into the container containing the molten steel while being properly dispersed by hand. However, in the method of manually inserting the insulating material, it takes time to insert the insulating material. In addition, molten steel transferred from a converter to a container has a high temperature of 1600 DEG C or higher, so that there is a limitation in allowing a person to approach the vicinity of molten steel to perform work.

Thus, a method of inserting a thermal insulating material, which is not based on manual operation, has been developed. Patent Document 1 discloses a method in which a hopper containing a heat insulating material is provided above a container and the heat insulating material is dropped by the action of gravity. In the bottom portion of the hopper, a plurality of valve pieces are provided, and by opening each valve piece, the insulating material in the hopper can be discharged and charged into the container. In this way, the insulating material is supplied to the entire surface of the molten steel by injecting the insulating material from plural portions of the bottom of the hopper.

Patent Document 2 discloses a method in which a heat insulating material filled in a flexible container bag is disposed in a box-shaped jig having a bottom portion in a grid shape, the flexible container bag is torn with heat of molten steel, and the heat insulating material is dropped by the action of gravity . In this method, by allowing the insulating material to pass through the lattice, the time for which the insulating material continues to fall is prolonged. For this reason, the insulating material can be supplied to the entire surface of the molten steel by moving the box-shaped jig in the horizontal plane by the crane during falling of the insulating material.

Patent Document 3 discloses a method of introducing a heat insulating material into a turn-off containing molten steel using a carrier gas. In this method, a jet port of the nozzle is disposed between the lid of the tundish and the molten steel surface of the molten steel. From the jet port, the heat insulator is sprayed onto the molten steel bath surface together with the carrier gas. According to this method, the covering ratio of the insulating material to the molten steel surface is improved. According to Patent Document 3, it is possible to avoid over-injection of the insulating material and to appropriately increase the amount of the insulating material to be charged, which is effective for cost improvement.

Japanese Patent No. 2971829 Japanese Patent Application Laid-Open No. 61-219462 Japanese Patent Application Laid-Open No. 63-108954

In the methods described in Patent Documents 1 and 2, the insulating material can be uniformly supplied to the molten steel surface to some extent. However, in these methods, the insulating material is dropped by the action of gravity and supplied to the molten steel surface. In addition, since the insulating material needs to be charged in a short time, there is a limit to the number of the insulating materials to be divided. From the above, it is difficult to uniformly insert the insulating material to such an extent as to be satisfactory. For this reason, the exposed portion from the heat insulating material on the surface of the molten steel increases, which may result in insufficient heating effect. Further, if the exposure of the surface of the molten steel is intended to be reduced in order to secure a sufficient warming effect, there is a problem that the amount of the insulating material is excessive and the economical efficiency is deteriorated.

In addition, in the method described in Patent Documents 1 and 2, a part of the insulated insulating material is transferred to the ascending air flow and scattered around the equipment because the molten steel is at a high temperature and an upward flow is generated from the surface of the molten steel. There arises a problem that it is deteriorated.

On the other hand, in the method of Patent Document 3, since the insulating material is sprayed on the surface of the molten steel together with the carrier gas, it is uniformly supplied to the surface of the molten steel, and the effect of keeping warmth and the amount of insulating material can be appropriately used. However, Patent Document 3 describes the case where this method is applied to turn-on with a lid on the top, and there is no detailed description on a method of applying the same equipment in a container without a lid . When the method is applied to a container in which a lid is not provided, since the jet port of the nozzle is directed in the horizontal direction, the insulating material is likely to be transferred to the upward flow and scattered around. As a result, it is not possible to obtain a sufficient warming effect, or the use amount of the insulating material needs to be increased to secure a thermal insulation effect, and the economical efficiency is deteriorated.

In addition, there is a case where a slag reforming material or slag loam is supplied to the surface of the molten steel. Also in this case, unless the slag reforming material or the slag solidification fire is uniformly provided on the surface of molten steel, the effect of slag reforming or slag solidification can not be sufficiently obtained. Further, if the slag reforming material or the slag solidification fire is scattered, the environment and the economical efficiency are deteriorated. In addition, the same problem may occur when an additive is added to a molten metal other than molten steel, for example, molten iron.

Therefore, regardless of whether or not the container is provided with a lid, the present invention can uniformly supply the additive material to the surface of the molten metal contained in the container, thereby achieving both the sufficient addition effect of the additive material and the reduction in the additive material usage amount And an additive material charging device.

The present invention relates to the following method (1) for adding an additive, and (2) the additive-adding device.

(1) A method for introducing an additive into a container containing molten metal,

A nozzle disposing step of disposing a nozzle above molten metal contained in the container,

And an additive material ejecting step of ejecting the additive material from the ejection port of the nozzle by transporting the additive material by the carrier gas to the nozzle,

Wherein an area of the jet port is larger than an area of the introduction port in the nozzle.

(2) An apparatus for introducing an additive into a container containing molten metal,

A container for containing the additive;

A nozzle disposed above the molten metal accommodated in the container, the nozzle having an injection port at the lower end of the nozzle;

An additive material conveying pipe connecting the nozzle and the container,

And a carrier gas introducing device for supplying a carrier gas to the additive material conveying pipe and conveying the additive contained in the container to the nozzle through the additive material conveying pipe by the carrier gas,

Wherein an area of the jet port is larger than an area of the introduction port in the nozzle.

By the method of adding the additive and the additive material feeding device, regardless of whether or not the container is provided with a lid, the additive material is uniformly supplied to the surface of the molten metal contained in the container, Reduction can be achieved at the same time. As an effect of the addition of the additive, for example, when the additive is a heat insulating material, a sufficient warming effect can be obtained.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view of a insulator insertion apparatus according to an embodiment of the present invention; FIG.
Fig. 2 is a cross-sectional view showing a configuration in the vicinity of a connecting portion between a return pipe and a carrier gas introducing device.

The inventors of the present invention conducted various experiments on a method of uniformly supplying a heat insulating material to the surface of molten steel in a container not provided with a lid. First, one nozzle having a jet port at the lower end was disposed above the surface of the molten steel in a container not provided with a lid, and a test was performed to inject a thermal insulator from the jet port of the nozzle onto the molten steel surface by the carrier gas . The diameter of the opening of the container was 3.0 m or more. At this time, the jet port of the nozzle was directed downward vertically.

As a result, when the distance in the height direction from the top of the container to the jet port of the nozzle (hereinafter also referred to as " nozzle height ") was larger than 1.2 m, That is, if the amount of the heat insulating material used is increased to such an extent that the heat insulating material can be uniformly supplied to the surface of the molten steel, the amount of the insulating material scattered by the upward flow from the surface of the molten steel is increased.

On the other hand, when the nozzle height was 1.2 m or less, the insulating material did not substantially scatter. However, in this case, the insulating material could not be uniformly supplied to the surface of the molten steel, and the amount of the insulating material deposited on the surface of the molten steel varied. Particularly, when the height of the nozzle is less than 0.4 m, the amount of the heat insulating material deposited on the molten steel surface was remarkable.

The present inventors have also studied to change the number and shape of the nozzle air outlets. However, in the case where a single nozzle is used, a sufficient insulating effect is uniformly supplied to the surface of the molten steel in a container having no lid and the diameter of the opening is 3.0 m or more, It was expected to be difficult.

The inventors of the present invention conducted a test in which two nozzles were provided above the molten steel accommodated in the vessel and the insulator was charged into the vessel. As a result, it was confirmed that the insulating material was uniformly dispersed and supplied to the surface of the molten steel, and scattering of the insulating material due to the upward flow of molten steel was reduced. Particularly, when the height of the nozzle is 0.4 m or more and 1.2 m or less, the uniformity of the insulating material supplied to the surface of the molten steel is high, and the scattering of the insulating material due to the upward flow of molten steel is not substantially caused.

Further, the inventors of the present invention have examined the proper amount of the thermal insulation material and confirmed that the balance between the thermal insulation effect and the thermal insulation material usage becomes better when the average thickness of the thermal insulation material deposited on the surface of the molten steel is 5 mm or more and 25 mm or less. Since the diameter of the heat insulating material is generally about 5 mm, when the average thickness is less than 5 mm, the entire molten steel surface can not be covered. When the average thickness exceeds 25 mm, the effect of keeping the molten steel warm against the increase in the average thickness becomes saturated and becomes almost constant, resulting in an excessive use of the insulator.

The present invention has been completed based on the above findings.

As described above, the additive material dosing method of the present invention is a method of adding an additive material to a container containing molten metal. The method includes a nozzle arrangement step of disposing a nozzle above molten metal contained in a vessel, and an additive material ejecting step of feeding the additive into a nozzle by a carrier gas and ejecting the additive from an ejection port of the nozzle. In the nozzle, the area of the jet port is larger than the area of the inlet port.

The diameter of the opening of the container may be 3.0 m or more. In this case, in the additive material ejecting step, the distance in the height direction from the top end of the container to the ejection port is preferably 0.4 m or more and 1.2 m or less.

The additive may be a heat insulating material. In this case, in the additive material ejecting step, it is preferable that the additive is deposited on the surface of the molten metal at an average thickness of 5 mm or more and 25 mm or less.

The ratio of the area of the jet port to the area of the introduction port is preferably 2 or more. The molten metal may be molten steel. The nozzle disposing step may include a step of disposing a plurality of nozzles above the molten metal contained in the container.

As described above, the additive material dosing device of the present invention is an apparatus for injecting an additive material into a container containing molten metal. The apparatus includes a container, a nozzle, an additive material transfer pipe, and a carrier gas introducing device. The container accommodates the additive. The nozzle is disposed above the molten metal accommodated in the container, and the jet port of the nozzle is provided at the lower end of the nozzle. The additive return pipe connects the nozzle and the container. The carrier gas introducing device feeds the carrier gas to the additive material conveying pipe, and the additive contained in the container is conveyed to the nozzle through the additive material conveying pipe by the carrier gas. In the nozzle, the area of the jet port is larger than the area of the inlet port.

The ratio of the area of the jet port to the area of the introduction port is preferably 2 or more. The additive may be a heat insulating material. The molten metal may be molten steel. The additive material dosing device may have a plurality of nozzles. In this case, the additive material transfer pipe may connect each of the plurality of nozzles to the container, and the carrier gas introducing device may transport the additive contained in the container to each of the plurality of nozzles through the additive material transfer pipe.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, with reference to the accompanying drawings, an embodiment of the present invention will be described in detail as an example, in which the molten metal is molten steel and the additive is a heat insulating material.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing a constitution of a heat insulating material injecting apparatus according to an embodiment of the present invention; Fig. This insulator inserting device 20 includes a container 15 in which a thermal insulating material 14 is accommodated and a plurality of nozzles 11 (two in this embodiment) disposed above the molten steel 13 stored in the container 12, . The container 12 is used for receiving and transporting the molten steel 13. The container 12 is not provided with a lid and its upper portion is open.

The jet port 11a formed in each nozzle 11 is located at the lower end of the nozzle 11 and faces downward. The plurality of nozzles 11 are spaced apart from each other and arranged in a horizontal direction. It is preferable that a plurality of nozzles 11 are uniformly arranged on the surface of the molten steel 13 accommodated in the container 12 in plan view. Each of the nozzles 11 is connected to the container 15 through a transfer pipe 16. [

At the lower portion of the side wall of the container 15, a heat insulating material outlet 15a is formed. The return pipe 16 is connected to the heat insulating material outlet 15a. In the return pipe 16, a carrier gas introducing device 17 is connected in the vicinity of the heat insulating material outlet 15a. The carrier gas introducing device 17 introduces the carrier gas for conveying the heat insulating material 14 into the conveying pipe 16.

Fig. 2 is a cross-sectional view showing a configuration in the vicinity of a connecting portion between a return pipe and a carrier gas introducing device. The carrier gas introducing device 17 includes a carrier gas accommodating portion (not shown) containing a carrier gas and a carrier gas introducing pipe 21 for introducing a carrier gas accommodated in the carrier gas accommodating portion into the transfer pipe 16 have. As the carrier gas, it is preferable to use an inert gas such as argon gas or nitrogen gas. This is because the inert gas is hard to react with the molten steel (including the pick-up to the molten steel).

The portion 16a in the vicinity of the connection with the heat insulating material outlet 15a in the return pipe 16 is inclined downward in the direction away from the container 15, chute. In the return pipe 16, a portion adjacent to the first portion 16a (hereinafter referred to as a "second portion") 16b is substantially horizontal. The carrier gas introducing pipe 21 is connected to the second portion 16b of the transfer pipe 16. The carrier gas introducing pipe 21 and the transfer pipe 16 (second portion 16b) on the side of the container 15 from the connecting portion form an acute angle in the vicinity of this connecting portion.

A part of the heat insulating material 14 accommodated in the container 15 flows into the first part 16a of the conveying pipe 16 by the action of gravity and flows into the first part 16a of the second part 16b 16a. When the carrier gas is introduced into the second portion 16b of the transfer pipe 16 by starting the carrier gas introducing device 17 in this state and the carrier gas is introduced into the transfer pipe 16 mainly through the nozzle 11, . In Fig. 2, the direction of the main flow of the carrier gas is indicated by a dashed arrow. This is because a large amount of the heat insulating material 14 is present in the portion of the return pipe 16 on the container 15 side and the pressure loss is large and the carrier gas introducing pipe 21 is provided at the above- It depends on what is connected.

When the carrier gas flows through the transfer piping 16 as described above, the portion of the container 15 side from the connecting portion between the transfer piping 16 and the carrier gas introduction pipe 21 becomes negative pressure, , Is drawn to the vicinity of the connection portion, and is then transported by the carrier gas. In Fig. 2, the main transport direction of the insulating material is indicated by a white arrow. The thermal insulating material 14 accommodated in the container 15 is conveyed to the nozzle 11 through the conveying pipe 16 and ejected from the ejection port 11a of the nozzle 11. [ The upper limit of the length of the return pipe 16 is determined by the feeding ability of the carrier gas introducing device 17. [

The kind of the heat insulating material 14 contained in the container 15 is not particularly limited, but may be, for example, vermiculite. In this case, the diameter of the particles constituting the heat insulating material 14 is preferably 3 to 10 mm, and may be, for example, about 5 mm. If the diameter of the particles is less than 3 mm, the amount of the insulating material 14 scattered by the upward flow generated above the molten steel 13 can not be ignored. When the diameter of the particles exceeds 10 mm, it is difficult to smoothly carry the heat insulating material 14 by the carrier gas.

Below the container 15, a mass meter (not shown) is provided. The total mass of the container 15 and the heat insulating material 14 contained therein can be measured by the mass system. The amount of the insulator 14 charged per unit time into the container 12 can be calculated from the change with time of the mass measured by this mass meter.

This insulator insertion device 20 may be provided with a plurality of containers 15. In this case, one or a plurality of nozzles 11 are provided for each of the containers 15, and each of the nozzles 11 is connected to the container 16 via the transfer pipe 16 to which the carrier gas introducing device 17 is connected. It is possible to connect the antenna to the antenna 15.

The area of the outlet 11a of the carrier gas and the heat insulating material 14 is larger than the area of the inlet 11b of the carrier gas and the heat insulating material 14 (the connecting portion with the return pipe 16) . Here, with respect to the inlet 11b and the outlet 11a, the "area" is the area of the opening when viewed along the central axis of the nozzle 11.

It is assumed that a carrier gas is supplied from the transfer pipe 16 to the nozzle 11 at a volume velocity of V (m3 / min). In the nozzle 11, the area of the inlet 11b is S1 (m2) and the area of the outlet 11a is S2 (m2). The linear velocity V1 of the carrier gas at the inlet port 11a is V / S1 (m / min), and the linear velocity V2 of the carrier gas at the outlet port 11a is V / m / min). Since S1 < S2, V1 > V2. That is, the linear velocity of the carrier gas is reduced at the injection port 11a as compared with the introduction port 11b.

In order to transport the insulating material 14 to the nozzle 11, the linear velocity of the carrier gas in the transfer pipe 16 needs to be somewhat large. When the carrier gas has such a large linear velocity and the carrier gas is sprayed on the surface of the molten steel 13 in the container 12 together with the insulating material 14, the amount of the insulating material 14 scattering to the outside of the container 12 increases. The linear velocity of the carrier gas and the heat insulating material 14 is reduced due to the relationship S1 S1 between the area S1 of the inlet 11b and the area S2 of the outlet 11a in the nozzle 11, This scattering can be suppressed. In order to sufficiently obtain such an effect, the ratio (S2 / S1) of the area S2 of the injection port 11a to the area S1 of the introduction port 11b is preferably 2 or more and more preferably 3 or more.

It is preferable that the area of the nozzle 11 continuously increases from the inlet 11b to the outlet 11a. That is, it is preferable that the inner surface of the nozzle 11 has a shape widening downward, for example, a shape of a cone or a side surface of a truncated cone. In this case, the cross-sectional shape of the inner surface of the nozzle 11 becomes circular. It is preferable that the angle of expansion of the inner surface of the nozzle 11 is 60 to 90 degrees. This makes it easy to uniformly supply the heat insulating material 14 on the surface of the molten steel 13 and to prevent the heat insulating material 14 from being scattered by the upward flow generated above the molten steel 13 .

When the angle of spreading of the inner surface of the nozzle 11 is less than 60 degrees, the heat insulating material 14 is ejected concentrated around the center axis of the nozzle 11, so that the heat insulating material 14 is spread on the surface of the molten steel 13 It can not be uniformly supplied. On the other hand, when the angle of spreading the inner surface of the nozzle 11 exceeds 90 degrees, the thermal insulating material 14 spreads out from the air blow-out port 11a so that the downward velocity component of the thermal insulating material 14 is reduced, The amount of insulation that splashes increases.

The number of the carrier piping 16 and the number of the carrier gas introducing apparatuses 17 is equal to the number of the nozzles 11 and the number of the carrier gas introducing apparatuses 17, And a return pipe 16 are provided. The number of the transfer piping 16 and the carrier gas introduction device 17 may be smaller than the number of the nozzles 11 without adopting such a configuration. In this case, it is possible to dispose the corresponding carrier gas introducing device 17 in any nozzle 11 by branching the return pipe 16. [

However, when the number of the return pipe 16 and the number of the carrier gas introducing devices 17 is smaller than the number of the nozzles 11, the following problems may arise. That is, when a trouble such as accumulation of the heat insulating material 14 occurs in the part of the return pipe 16 before branching (the part on the side of the carrier gas introducing device 17 from the branch point), the nozzle connected to the return pipe 16 The heat insulating material 14 can not be conveyed to any part of the housing 11. In the return pipe 16, the heat insulating material 14 conveyed in the portion before the branching is not evenly distributed to the post-branch portion (the portion on the nozzle 11 side from the branch point) May occur.

The number of the return pipes 16 and the number of the carrier gas introducing devices 17 is made equal to the number of the nozzles 11 and one single carrier gas introducing device 17 and one return pipe It is possible to prevent the above-described problem from occurring by providing the light emitting element 16.

The shape of the opening of the container 12 is, for example, circular, and its diameter is 3.0 m or more, for example. When the opening of the container 12 has a circular shape, the container 12 has, for example, a cylindrical shape with a bottom.

The shape of the opening of the container 12 may not be circular, and may be, for example, polygonal (for example, rectangular), elliptical, or irregular. In this case, the diameter of the circle (the diameter defined in this manner, hereinafter referred to as "diameter of the opening") which is the same as the area of the opening of the container 12 is 3.0 m or more, for example. The inner surface of the nozzle 11 may have a shape adapted to the shape of the opening of the container 12. For example, when the shape of the opening of the container 12 is a rectangle, the shape of the cross section of the inner surface of the nozzle 11 may also be a rectangle. As a result, the heat insulating material 14 can be efficiently and uniformly supplied to the surface of the molten steel 13. The inner surface of the nozzle 11 may not have a shape adapted to the shape of the opening of the container 12. [

When the diameter of the opening is less than 3.0 m, it is easy to uniformly supply the insulating material 14 to the surface of the molten steel 13 even if the insulating material 14 is charged by one nozzle 11. The upper limit of the diameter of the opening of the container 12 is not particularly limited.

Hereinafter, the height H in the height direction from the upper end of the container 12 to the jet port 11a of the nozzle 11 (lower end of the nozzle 11) is referred to as " nozzle height ". When the diameter of the opening of the container 12 is 3.0 m or more, the nozzle height H is preferably 0.4 m or more and 1.2 m or less. As a result, the heat insulating material 14 can be uniformly supplied to the surface of the molten steel 13, and scattering of the heat insulating material 14 can be suppressed. The nozzle height H of each nozzle 11 may be the same as or different from the nozzle height H of the other nozzles 11.

The number and arrangement of the nozzles 11 are appropriately set so that the insulating material 14 can be uniformly supplied onto the surface of the molten steel 13 by the size and shape of the container 12. [

Next, a method of inserting a thermal insulating material according to an embodiment of the present invention will be described.

Hereinafter, it is assumed that the container 12 is a ladle into which molten steel flows after completion of blowing in the converter, but the container 12 in the present invention is not limited to this. These lakes are moved by the ladle conveying carriage to a position below the plurality of nozzles 11 provided in the insulator insertion apparatus 20. As a result, a plurality of nozzles 11 are arranged above the molten steel 13 accommodated in the ladle. In this state, the nozzle height H is preferably 0.4 m or more and 1.2 m or less.

Next, the carrier gas introducing device 17 is activated to introduce the carrier gas into the transfer pipe 16. [ Therefore, the heat insulating material 14 is conveyed in the conveying piping 16. Here, the carrier gas introducing device 17 may be started after the ladle carrier truck stops, or may be started when the ladle carrier truck is moving.

The heat insulating material 14 conveyed in the return pipe 16 is ejected together with the carrier gas from the ejection port 11a at the lower end of the nozzle 11 and put into the ladle. The jetted insulating material 14 is uniformly supplied to the surface of the molten steel 13 contained in the ladle. When the nozzle height H is 0.4 m or more and 1.2 m or less, the uniformity of the insulating material 14 supplied to the surface of the molten steel 13 becomes high. At this time, if the inner surface of the nozzle 11 has a shape that widens downward, the uniformity of the insulating material 14 supplied to the surface of the molten steel 13 becomes higher.

After the predetermined amount of the heat insulating material 14 is charged, the carrier gas introducing device 17 is stopped and the insertion of the heat insulating material 14 is completed. The charging time of the insulating material 14 varies depending on the amount of charge, but is, for example, about 10 to 30 seconds. Thereafter, the ladle is transported to the place where the next process, for example the secondary refining process, is carried out.

The surface of the molten steel 13 and the heat insulating material 14 covering the surface of the molten steel 13 can be visually recognized without using a special instrument. Therefore, the ratio (coverage) of the area of the entire surface of the molten steel 13 covered with the insulating material 14 can be estimated by observing the inside of the ladle appropriately.

(Mass) and coverage of the thermal insulating material 14 based on the following equation, the thermal conductivity of the molten steel 13 (the thermal conductivity of the molten steel 13) The average thickness of the heat insulating material 10 deposited on the surface of the insulating substrate 10 can be obtained.

[Total surface area of molten steel] (m 2) x [Coverage] (%) x 10 [Volume of insulation material] (kg / m 3)

It is preferable to insert the insulating material 14 so that the average thickness of the insulating material deposited layer becomes 5 mm or more and 25 mm or less. In this case, the balance between the heat retaining effect by the heat insulating material 14 and the amount of use of the heat insulating material 14 becomes good. That is, a sufficient warming effect can be obtained, and excessive use of the insulating material 14 can be avoided.

The present invention is not limited to the above-described embodiments, but may be modified in various ways without departing from the gist of the invention. For example, in the above embodiment, the lid (lid) is not provided in the container 12, but the present invention can also be applied to the container 12 provided with the lid. In this case, the nozzle 11 is arranged so that the jet port 11a of the nozzle 11 is positioned between the surface of the molten steel 13 and the lid.

The additive may be, for example, a slag reforming material or a slag solidification material other than a heat insulating material. The molten metal may be, for example, molten iron in addition to molten steel, or molten metal other than iron. The number of the nozzles 11 may be three or more, and may be one when the opening of the container is sufficiently small.

Example

In order to confirm the effect of the present invention, a test of putting a thermal insulating material in a container under different conditions was carried out, and the rate of temperature decrease of molten steel in each case was measured. In any case, first, 350 to 360 tons of molten steel treated in a 350 t capacity subzero desorption furnace was used as a ladle as a vessel. The temperature of the molten steel after casting was 1590 to 1610 캜. At the time of excavation, no iron alloy containing C, Si, Mn, Al or the like was added but only 1.0 to 1.5 kg / t of calcium oxide was added. The openings of the lasers were circular in shape and had a diameter of 4.7 m. Therefore, the surface area of the molten steel accommodated in the ladle was 17.3 m 2.

Next, the ladle was moved about 10 m in the direction away from the converter, and the temperature measurement probe for molten steel was inserted into molten steel in the ladle from above, and the temperature of the molten steel was measured. The movement of the lasers was done using a ladle carriage carriage (the same is true when moving the lanes in the following description). Thereafter, the lasers were moved by about 7 m in the direction away from the converter, and the insulator was put into the ladle. For the sake of comparison, a test was also conducted in which inserting of the insulating material was not performed.

The insulator was charged by a insulator insertion device having the constitution shown in Fig. The nozzle was connected to the container by a return pipe of about 20 m. The container contained a papermaking thermal insulation material having a particle diameter of 5 mm or more and 10 mm or less. The bulk density of this insulating material was 0.5 t / m 3, and it was expected that the bulk density would be the same even when deposited on the surface of the molten steel. A steel pipe having an inner diameter of 105.3 mm was used as the return pipe. The end of the return pipe on the nozzle side is configured to be detachable and can be replaced by a different length. The nozzle height was adjusted by exchanging the end of the return pipe.

Industrial nitrogen was used as the carrier gas introduced by the carrier gas introducing device, and this industrial nitrogen was transported at a flow rate of 10 m < 3 > / min and introduced into the pipe.

After completion of the insertion of the insulating material, the coating rate of the molten steel surface by the insulating material (hereinafter simply referred to as " covering rate ") was visually estimated. Thereafter, the ladle was moved for the secondary refining process, and the temperature of the molten steel was measured by the same method as above before the secondary refining process. Then, the temperature decrease rate was calculated from the difference between the temperature measured for the first time and the temperature measured for the second time with respect to molten steel and the elapsed time from the first measurement to the second measurement.

Table 1 shows the test results (the coating ratio, the average thickness of the insulating material deposited on the molten steel, and the amount of the molten steel) in the test conditions (the number of nozzles, the ratio and height of the jet port area to the inlet port area, The rate of temperature decrease of < / RTI >

In the test according to the condition A, the insulator was not supplied. In the tests according to conditions B and C, the insulating material was injected using only one nozzle. In the tests according to the conditions D to H, the insulating material was injected using two nozzles. In the test according to the condition B, a nozzle having a ratio of the jetting area to the area of the introduction port of 1 was used, and in the tests of the conditions C to H, the nozzle having the ratio of the jetting area to the area of the introduction port was used. The method of inserting the insulating material by the conditions C to H is an embodiment of the present invention, and the method of inserting the insulating material by the conditions A and B is a comparative example which does not satisfy the requirements of the present invention.

The temperature decrease rate of the molten steel was 0.45 ° C / min in the test under the test condition A, which was larger than the test under the other conditions. This is probably because the amount of heat radiation from the surface of the molten steel was large because the insulator was not charged.

From this result, when 70 minutes have elapsed since the launching from the converter, the temperature of the molten steel is lowered by 31.5 DEG C when the insulator is not supplied. When the temperature lowering rate of molten steel is suppressed to 0.40 캜 / min, the temperature drop of molten steel after 70 minutes can be suppressed by 3.5 캜, as compared with the case where the heat insulating material is not supplied. As a result, there is no need to excessively raise the temperature of the molten steel from the converter, and the temperature of the molten steel in the converter can be reduced to such an extent that a meaningful cost reduction effect can be obtained.

In the test under test condition B, the coating rate was 40%, and the temperature decrease rate of molten steel was 0.43 ° C / min. On the contrary, in the test under test condition C, the coating rate was 60%, and the temperature decrease rate of molten steel was 0.41 ° C / min. From this result, it was confirmed that the use of a nozzle having a large ratio of the jet port area to the inlet port area can increase the coating rate and reduce the rate of temperature decrease of molten steel.

In the case of using these single nozzles, in the tests under the test conditions D to H, the coating rate was 65 to 90%, and the temperature decrease rate of molten steel was 0.35 to 0.40 ° C / min. From this result, it can be seen that, in the case of using lasers having an opening diameter of at least 4.7 m, the coating rate can be increased in the case of using two nozzles as compared with the case of using one nozzle, It was confirmed that the temperature lowering rate could be reduced. However, the test was conducted using lasers having an opening diameter of 2 m. As a result, even when one nozzle having a ratio of the jetting port area to the inlet port area was 3, the coating rate was sufficiently increased and the rate of temperature decrease of molten steel was reduced Could.

In all of the test conditions D to H, the above-described cost reduction effect is obtained by suppressing the temperature lowering rate of molten steel. Particularly, in the test conditions D, G, and H, it was confirmed that the covering ratio was as large as 90%, the temperature lowering rate was as low as 0.35 to 0.36 캜 / min, and the effect of sufficiently suppressing the temperature drop was obtained.

In the test by the test condition E, the coating rate was lower than the test by the test condition D. This is considered to be related to the fact that the height of the nozzle was 1.0 m in the test condition D, and 0.3 m in the test condition E. In the test according to the test condition F, the amount of the insulating material scattered to the outside of the ladle was higher than that of the test according to the test condition D, as it was moved to the ascending current from above the molten steel. This is considered to be related to that the height of the nozzle was as high as 1.5 m in the test condition F, while it was 1.0 m in the test condition D.

In the test by the test condition G, the average thickness of the insulator deposited on the molten steel was larger than that of the test by the test condition D, and the temperature decrease rate of the molten steel was suppressed. This is related to the fact that the amount of the insulating material to be charged was 50 kg in the test condition D, and 200 kg in the test condition G. [ From this result, it can be seen that the effect of suppressing the temperature decrease of the molten steel is increased by increasing the average thickness of the insulating material from 6 mm to 25 mm.

In the test condition H, the amount of the insulating material was 250 kg, which was larger than the test condition G. In the test by the test condition H, the average thickness of the heat insulators deposited on the molten steel was larger than the test by the test condition G, but the temperature decrease rate of the molten steel was the same. From this result, it can be seen that the effect of suppressing the temperature drop of the molten steel is almost saturated when the average thickness of the insulating material is 25 mm or more.

11: Nozzle 11a:
12: vessel 13: molten steel
14: Insulation 15: Container
16: Return piping 17: Carrier gas introduction device
20: Insulation device

Claims (12)

A method for introducing an additive into a container containing molten metal,
A nozzle disposing step of disposing a nozzle above molten metal contained in the container,
And an additive material ejecting step of ejecting the additive material from the ejection port of the nozzle by transporting the additive material to the nozzle by the carrier gas,
Wherein an area of the jet port is larger than an area of the introduction port in the nozzle. The method according to claim 1,
Wherein the opening of the container has a diameter of 3.0 m or more,
Wherein the distance from the upper end of the container to the jet port in the height direction is 0.4 m or more and 1.2 m or less in the additive material jetting step. The method according to claim 1 or 2,
Wherein the additive is a heat insulating material. The method of claim 3,
Wherein the additive material is deposited on the surface of the molten metal at an average thickness of 5 mm or more and 25 mm or less in the additive material ejecting step. The method according to any one of claims 1 to 4,
Wherein the ratio of the area of the injection port to the area of the introduction port is 2 or more. The method according to any one of claims 1 to 5,
Wherein the molten metal is molten steel. The method according to any one of claims 1 to 6,
Wherein the nozzle disposing step includes disposing a plurality of the nozzles above molten metal contained in the container. An apparatus for introducing an additive into a container containing molten metal,
A container for containing the additive;
A nozzle disposed above the molten metal accommodated in the container, the nozzle having an injection port at the lower end of the nozzle;
An additive material conveying pipe connecting the nozzle and the container,
And a carrier gas introducing device for supplying a carrier gas to the additive material conveying pipe and conveying the additive contained in the container to the nozzle through the additive material conveying pipe by the carrier gas,
Wherein an area of the jet port is larger than an area of the introduction port in the nozzle. The method of claim 8,
Wherein the ratio of the area of the injection port to the area of the introduction port is 2 or more. The method according to claim 8 or 9,
Wherein the additive is a heat insulating material. The method according to any one of claims 8 to 10,
Wherein the molten metal is molten steel. The method according to any one of claims 8 to 11,
A plurality of said nozzles,
Wherein the additive material conveying pipe connects each of the plurality of nozzles and the container,
Wherein the carrier gas introducing device conveys the additive contained in the container to each of the plurality of nozzles via the additive material transfer pipe.

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