JP2010089098A - Apparatus and method for preventing filter clogging serving as apparatus and method for cleaning molten metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for preventing filter clogging serving as an apparatus for cleaning molten metal which removes foreign matters deposited on an foreign matter removing filter and cleans molten metal with gas supplied to a tapping pipe. <P>SOLUTION: The foreign matter removing filter 6 is mounted on a tapping pipe 5 extending into a storage container 3. A gas supply means 8 is provided downstream from the filter 6 in the tapping direction (the direction of an arrow L), and a pipe opening/closing means 7 is provided further downstream from the gas supply means. The pipe opening/closing means 7 is closed, and pressurized gas is supplied into the tapping pipe 5 from the gas supply means 8. The gas advances in the direction of an arrow M, and passes through the foreign matter removing filter 6. During the passage, the gas is collided with the foreign matters deposited on a filter surface 6a on the side contact with molten metal in the storage container to separate and break the foreign matters and to perform the backwash. Further, after the gas passes the filter 6, the gas allows foreign matters to be afloat by the bubbling to clean the molten metal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a filter for preventing clogging of a filter due to gas supply in an apparatus in which a foreign matter removal filter is provided in a melting furnace or a holding furnace and the foreign matter mixed in the molten metal is caught by the filter when the molten metal is discharged. The present invention relates to a molten metal purification apparatus and method.

  Inclusion of inclusions in the molten metal greatly affects the quality of the cast product, for example, in the casting process. Therefore, conventionally, an apparatus or a removal method has been developed for removing inclusions such as oxides and impurities existing in the molten metal using a filter. Further, an apparatus or a method for purifying molten metal by promoting the floating of inclusions by gas bubbling has been developed. However, if the filter has been used for a long time, inclusions adhere to and accumulate on the surface of the filter, resulting in clogging and a problem that the molten metal passage speed of the filter decreases. For this reason, it is necessary to periodically replace the filter, and each time a furnace is cooled, a hot water draining operation, a furnace re-heating operation or the like occurs, there is a problem that energy loss is large. Further, in the case of gas bubbling, the gas bubbling itself is not so high in cleaning ability, and there is a problem that purification is insufficient only by gas bubbling.

  Therefore, Patent Document 1 shown below discloses a technique that uses an inclusion removal filter and gas bubbling in combination. Specifically, in a melting and holding furnace, after the gas supplied through the gas jetting means is jetted into the molten metal in the furnace through the gas jetting filter, the molten metal is disposed in the upper part of the same furnace. It is configured to pass through the filter into the atmosphere. Patent Document 2 shown below discloses a technique for removing inclusions deposited and attached to a filter and recovering the reduced filter function of the filter. Specifically, in a melting and holding furnace or the like, a bubble supply block is provided below or around a filter provided for filtering molten metal, and bubbles supplied from the bubble supply block are deposited or adhered to the surface of the filter. It is lifted by colliding with inclusions and removed from the surface of the filter.

JP-A-5-8024 JP 2006-122935 A

  However, although the technology of Patent Document 1 has both the inclusion removal function by the filter and the cleaning function by gas bubbling, the filter does not have the function of removing the inclusions attached to the filter. In addition, since both of them are configured separately, a filter for removing inclusions and a filter for gas bubbling are required, resulting in an increase in equipment cost. Moreover, in the technique of the said patent document 2, in order to make the bubble supplied from a bubble supply block collide from the filter surface of the side to which the inclusion has adhered with respect to a filter, ie, the filter is not backwashed with a bubble. Therefore, the inclusions adhering to the surface of the filter can be removed with a certain probability, but it is difficult to remove the inclusions that have entered the eye of the filter.

  Therefore, the present invention has been made in view of such circumstances, and by supplying gas to a foreign matter removal filter provided in a melting furnace or holding furnace containing molten metal, foreign matter attached to the filter is removed. An object of the present invention is to provide a filter clogging prevention device and a metal melt purification device and method capable of removing the metal melt by bubbling and cleaning the metal melt.

  In order to solve the above-described problems, the foreign matter removal filter clogging prevention device and the prevention method thereof according to the present invention are characterized by having the following configurations.

(Aspect of the Invention)
As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is for the purpose of facilitating the understanding of the technology described in this specification, and is intended to limit the technical features described in this specification and combinations thereof to those described in the following sections. Absent. In other words, the technical features should be interpreted in consideration of the description accompanying each section, the description of the examples, etc. Moreover, the aspect which deleted the component from the aspect of each term can also become one aspect. In the following items, each of items (1) to (2) corresponds to each of claims 1 to 2.

(1) piping for discharging molten metal in a storage container including a melting furnace or a holding furnace;
A foreign matter removal filter attached to a portion of the pipe extending into the storage container;
A pipe opening / closing means provided in a portion of the pipe downstream of the position where the foreign matter removal filter is provided with respect to the flow direction of the hot water;
Filter clogging prevention comprising gas (bubble) supply means provided in a portion of the pipe between a position where the foreign matter removing filter is attached and a position where the pipe opening / closing means is provided Equipment and purification equipment for molten metal.

  Molten metal stored in the container and discharged into the container are performed by the molten metal control means (device). For example, when the storage container is a melting furnace or a holding furnace, an atmospheric pressure adjusting means can be provided as a molten metal control means on the melting furnace or the like side. In this case, the melting furnace or the like needs to be in an airtight state. When the air pressure inside the container is increased or reduced by the atmospheric pressure adjusting means in a state where airtightness such as a melting furnace is ensured, for example, melting is performed via a molten metal flow path composed of a hot water discharge pipe, a hot water absorption pipe, and the like. The molten metal stored in the furnace or the like can be easily discharged from the melting furnace or the like to the outside, or the molten metal can be sucked into the melting furnace or the like from the outside.

Here, when the molten metal in the melting furnace is discharged, the following configuration may be employed. A discharge pipe provided for discharging the molten metal from the melting furnace extends to the melting furnace. A filter (foreign matter removal filter) for removing foreign matter / inclusions mixed in the molten metal at the time of tapping is attached to a pipe portion extending into the melting furnace. For example, the filter may be provided only at the mouth of the pipe, the form where the mouth of the pipe and the end of the pipe are in a filter shape, or the form provided so as to block the flow path in the pipe. Good. Examples of the material of the filter include a refractory material made of SiO ₂ and Al ₂ O ₃ , or a wire mesh provided with a refractory coating.

  The pipe opening / closing means (device) is for switching the hot water supply pipe (the hot water flow path) to an open state or a closed state. The pipe opening / closing means is provided on the downstream side of the foreign matter removal filter with respect to the flowing direction of the hot water, and closes the flow path of the hot water by switching to the closed state. As a result, the flow path to the downstream side of the open / close means of the hot water piping can be blocked, and the molten metal in the melting furnace does not flow in the direction of the hot water. As the pipe opening / closing means, a stopper plug or an opening / closing valve fitted into the outlet of the hot water supply pipe opposite to the container side may be used.

The gas (bubble) supply means is for supplying pressurized gas into the hot water supply pipe. The gas supply means is provided at a position between the position of the foreign matter removal filter and the position of the pipe opening / closing means with respect to the direction in which the hot water flows. By supplying the gas, the gas is passed through a foreign matter removing filter, and foreign matters and inclusions adhering to the filter (infiltrated not only on the surface of the filter but also inside) are back-washed. As the gas, an inert gas such as N ₂ or Ar, or air may be used.

(2) A filter clogging prevention method and a molten metal in which the foreign matter trapped in the foreign matter removal filter is backwashed and the molten metal is cleaned using the filter clogging prevention device and the molten metal purifier according to item 1 Purification method,
After stopping the discharge of hot water downstream from the pipe opening and closing means by closing the pipe opening and closing means,
Operate the gas supply means to a gas supply state,
The gas supplied from the gas supply means is sent in the direction of the foreign matter removal filter through the pipe, passed from the downstream side to the upstream side of the foreign matter removal filter, and discharged into the storage container. A method for preventing clogging of a filter and a method for purifying a molten metal, wherein the foreign matter trapped on the surface on the container side is back-washed and the molten metal in the storage container is cleaned by bubbling the released gas.

  In the open state of the pipe opening / closing means, that is, in the state where the piping for hot water is not blocked by the pipe opening / closing means, the airtightness of the storage container such as the melting furnace or the holding furnace is secured, and the pressure adjusting means (pipe opening / closing means) Pressurize the pressure inside the container. Thereby, the molten metal in the storage container is discharged through the hot water piping. At this time, since the hot water is discharged through the foreign matter removing filter provided in the storage container, the foreign matter mixed in the molten metal is captured by the filter. In addition to adhering to the surface of the filter on the storage container side, the trapped foreign matter enters the eyes of the filter.

  In a state where the molten metal is stored in a storage container such as a melting furnace or a holding furnace, the pipe opening / closing means is closed. As a result, the piping (hot water flow path) is interrupted in the middle, so even if the pressure on the storage container side is increased relative to the pipe opening / closing means, for example, the pressure inside the hot water melting pipe on the storage container side or the storage container Even if the inner pressure is increased, the molten metal in the storage container does not flow in the direction of the hot water.

  After the pipe opening / closing means is closed, the gas supply means is operated to pressurize and supply gas from the means into the hot water supply pipe. At this time, since the pipe opening / closing means is in a closed state, the supplied gas does not proceed in the downstream direction (direction with respect to the flowing direction of the hot water), and the upstream direction in which the foreign matter removal filter is disposed. Proceed to The gas passes through the foreign matter removal filter from the hot water piping side and reaches the storage container side. In the foreign matter removing filter, as described above, when the hot water is discharged, the foreign matter adheres to the surface on the side of the storage container and gets into the eyes of the filter. The pressurized gas is in the form of fine bubbles and collides with a foreign substance attached to or submerged in the filter, and the foreign substance is peeled off or destroyed from the filter. That is, the foreign matter captured by the filter at the time of tapping is backwashed by the pressurized gas supplied. Thereby, clogging due to foreign matter in the filter can be prevented, and foreign matter in the molten metal can be removed by the back-washed filter at the time of hot water supply, and the hot water flow rate can be supplied without decreasing.

  The bubble-like gas that has passed through the foreign matter removal filter rises in the molten metal in the storage container (this is called gas bubbling). A foreign substance or the like peeled off and destroyed from the filter accompanying the gas bubbling can be floated in the storage container, and the molten metal can be cleaned. When the gas is supplied, if the storage container has a structure that can be airtight, the inside of the container may be equal to the atmospheric pressure in order to increase the collision energy of the gas (bubbles). desirable.

  According to the present invention, a pressurized gas is supplied to and passed through a foreign matter removal filter provided in a melting furnace or a holding furnace containing molten metal from a direction opposite to the direction of outgoing hot water. The foreign matter adhering to or sinking into the filter can be backwashed to prevent clogging by the foreign matter adhering to the filter. Further, the gas that has passed through the filter can be discharged into a melting furnace or the like, and the backwashed foreign matter can be lifted by bubbling the gas to clean the molten metal. Moreover, a clean molten metal can be stably discharged without reducing the filtering function of the filter and the flow rate of the molten metal.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments, and includes various embodiments based on the knowledge of those skilled in the art, including the embodiments described in the above section (Aspects of the Invention). It can be carried out in a modified or improved manner.

FIG. 1 is a partial cross-sectional view showing an embodiment of the present filter clogging prevention device and a molten metal purification device.
The filter clogging prevention device 1 and the molten metal purification device 1 are disposed in the storage container 3 and the molten metal flow path 5 that extends to the storage container 3 in which the molten metal 2 is stored. The foreign matter removal filter 6 attached to the molten metal flow path section, the flow path opening / closing means (device) 7 provided on the downstream side of the foreign matter removal filter 6 with respect to the direction of the molten metal, and the foreign matter A gas (bubble) supply means 8 provided in a molten metal flow path portion between the removal filter 6 and the flow path opening / closing means 7 is schematically configured. Examples of the storage container 3 include a melting furnace and a holding furnace.

The molten metal flow path 5 is a hot water discharge pipe for discharging the molten metal 2 in the storage container 3. The molten metal to be discharged flows in the direction of arrow L shown in the drawing. The foreign matter removing filter 6 may be provided in the storage container 3, and may be provided in, for example, an end of the hot water piping 5, the inside of the hot water piping 5, or the like. The filter 6 shown in FIG. 1 is provided in the shape which comprises the opening part and end part side wall part of piping so that the piping 5 for hot water supply may be extended. The foreign matter removal filter 6 can be made of a refractory material made of SiO ₂ or Al ₂ O ₃ , or a wire mesh provided with a refractory coating.

  The channel opening / closing means (device) 7 is a pipe opening / closing means for switching the hot water supply pipe 5 to an open state or a closed state. The pipe opening / closing means 7 may be disposed downstream of the foreign matter removal filter 6 (with respect to the direction of the arrow L through which the hot water flows), and the position thereof is, for example, outside the storage container 3 and the molten metal flow path 5. Even if it is provided in the mouth part (the mouth part on the side opposite to the side where the filter is attached. The filter in FIG. 1 corresponds to this) or in the molten metal flow path 5 part in the storage container 3. It may be provided. As a specific pipe opening / closing means, for example, a plug fitted in a hot water outlet as shown in FIG. The plug is preferably in a form that can be controlled by a control means. In addition to this, for example, an open / close valve electrically connected to the control means and operated to open / close may be used. By switching the pipe opening / closing means 7 to the closed state, the flow path of the hot water is blocked, and the molten metal does not flow in the hot water supply pipe 5 to the downstream side of the opening / closing means 7.

The gas (bubble) supply means 8 is for supplying pressurized gas (bubbles) into the hot water supply pipe 5 in order to clean the foreign matter removal filter 6. The gas supply means 8 is composed of a gas reservoir 9 and an opening / closing valve 10, and the opening / closing valve 10 is controlled to open / close by a valve control means not shown in the figure. The gas supply means 8 is provided in a hot water piping section between the foreign matter removal filter 6 and the pipe opening / closing means 7. Further, the position may be outside the storage container 3 or inside the storage container 3, similarly to the pipe opening / closing means 7. As the gas to be supplied, for example, an inert gas such as N ₂ or Ar can be used. When the opening / closing valve 10 is controlled to open, the gas in the gas storage unit 9 is supplied as fine bubbles to the hot water supply pipe 5 and proceeds in the direction indicated by the arrow M.

Here, FIG. 2 and FIG. 3 show the removal of foreign matter / inclusions in the molten metal by the foreign matter removal filter 6 and the backwashing and gas bubbling of the foreign matter (inclusions) attached / deposited on the filter 6 with the supply gas This will be explained based on. The foreign substance removal filter 6 shown in FIGS. 2 and 3 is in the form of being provided inside the hot water piping 5.
FIG. 2 shows how the molten metal is discharged, and the molten metal flows in the direction of arrow L. Although illustration is omitted, at this time, the pipe opening / closing means 7 is open. Foreign metal 11 is mixed in the molten metal on the storage container side (left side in the figure) with respect to the foreign material removal filter 6, and the foreign material 11 is captured when passing through the filter 6. Thereby, the foreign material in a molten metal is removed and a beautiful molten metal can be discharged. The trapped foreign matter 11 adheres to and accumulates on the surface 6a of the filter 6 on the storage container 3 side, and also enters the filter from the eyes of the filter.

  FIG. 3 shows how the foreign matter removal filter 6 is backwashed with gas. Although illustration is omitted, since the pipe opening / closing means 7 is closed and shut off at this time, the gas supplied from the gas supply means 8 passes through the hot water supply pipe 5 in the direction of the pipe opening / closing means 7 (storage container 3). Does not travel in the opposite direction), but proceeds in the direction of the foreign matter removal filter 6 (the direction of the arrow M). The gas is pressurized and supplied into the pipe, becomes fine bubbles, and passes through the foreign substance removal filter 6 in the direction of the storage container 3 (from right to left in the figure). At this time, the bubbles collide with the foreign matter adhering to and accumulating on the surface 6a of the foreign matter removing filter 6 on the storage container 3 side or the foreign matter entering the filter, and the foreign matter is crushed and separated. As a result, the foreign matter removal filter 6 can be back-washed to eliminate clogging caused by foreign matter, and a sufficient amount of molten metal can be supplied without reducing the flow rate through the filter when the hot water is discharged. In addition, since the gas that has passed through the foreign matter removal filter 6 rises (bubbles) in the molten metal, the crushed and separated foreign matter can be floated along with the bubbling of the gas. Degassing treatment of the contained hydrogen gas can be performed, and the molten metal can be cleaned.

  Returning to FIG. 1, in the state shown in the figure, in a state where the molten metal 2 is held in the storage container 3, the pipe opening / closing means 7 is controlled to be closed, and gas is supplied from the gas supply means 8 under pressure. Indicates the state. The gas becomes fine bubbles, travels in the direction of arrow M, and passes through the foreign matter removal filter 6. At that time, the bubble gas collides with the foreign substance 11 adhering to the filter surface 6a on the side in contact with the molten metal 2 in the container 3 or the foreign substance submerged in the filter, and is peeled and crushed. Wash. Further, since the gas that has passed through the foreign matter removal filter 6 is bubbled in the molten metal in the storage container 3, the separated and crushed foreign matter is levitated, and the hydrogen gas contained in the molten metal is degassed. Clean the molten metal. At this time, the atmospheric pressure in the storage container 3 is preferably set to be equal to the atmospheric pressure, for example, in order to enhance the effect of back washing with gas.

FIG. 4 is a partial cross-sectional view showing another embodiment of the present filter clogging prevention device and molten metal purification device. In addition, the same number is attached | subjected to the member same as the thing of the form shown in FIG. 1, and detailed description is abbreviate | omitted suitably.
The hot water supply pipe 5 extends through the storage container 3 in the vertical direction, and the tip thereof reaches the bottom surface of the container 3. The molten metal 2 in the storage container 3 is discharged in the direction indicated by the arrow L, and a foreign matter removing filter 6 is attached to the tip of the pipe 5 disposed in the container 3. A pipe opening / closing means 7 is provided at the end. A gas supply means 8 is connected to the pipe portion between the foreign matter removal filter 6 and the pipe opening / closing means 7, and the gas in the gas storage portion 9 is supplied into the hot water supply pipe 5 by opening / closing the opening / closing valve 10. .

  The storage container 3 has a structure that can have airtightness. When the inside of the storage container 3 is pressurized in the state of having airtightness, the molten metal 2 in the storage container 3 passes through the piping 5 for hot water. Hot water is poured out. Pressurization of the storage container 3 is performed by opening the valve 22. The operation is controlled by electrically connected control means (not shown). When the valve 22 is opened, the gas in the gas reservoir 9 is supplied. The gas supplied from the same gas storage unit 9 can be used as the gas supplied into the hot water discharge pipe 5 through the valve 10 and the gas supplied into the storage container 3 through the valve 22. In addition, the gas reservoir 9, the valve 10 and the valve 22 are connected by a three-way valve 21.

In the form shown in FIG. 4, the following operations are performed during the clogging prevention process of the foreign matter removal filter 6 and the cleaning process of the molten metal and when the molten metal is discharged.
During the clogging prevention process of the foreign matter removal filter and the cleaning process of the molten metal, the pipe opening / closing means 7 is first controlled to be closed by the control means while the molten metal is held in the storage container, and the outlet piping Close the 5 tap. Next, the control means switches the opening direction of the three-way valve 21 to the valve 10 side, and opens the valve 10 to supply the gas in the gas reservoir 9 into the hot water supply pipe 5. Since the hot water outlet is closed by the pipe opening / closing means 7, the supplied gas advances in the direction of the foreign matter removal filter 6 (direction indicated by the arrow M).

  The gas is in the form of fine bubbles, passes through the foreign matter removal filter 6, and is released into the storage container 3. When the bubble-like gas passes, it collides with foreign matter adhering to the foreign matter removal filter 6 (filter surface 6a on the side in contact with the molten metal in the storage container 3) or foreign matter entering the filter, and the foreign matter is peeled off and pulverized. Then, the filter 6 is back-washed. Thereby, the foreign matter clogging of the foreign matter removal filter 6 can be eliminated, the excellent foreign matter removal function of the filter can be maintained, and a decrease in the amount of discharged hot water passing through the filter can be prevented. Further, since the bubble-like gas that has passed through the foreign matter removing filter 6 is bubbled in the storage container 3, foreign matters that have been crushed and peeled off along with the bubbling can be levitated and contained in the molten metal. Hydrogen gas can be degassed, and the molten metal in the storage container 3 is cleaned. At this time, the valve 22 is kept open to the atmosphere in order to increase the gas collision speed.

  When the molten metal is discharged, first, the control means controls the pipe opening / closing means 7 to be in an open state, and the hot water outlet of the piping 5 for hot water is opened. At this time, the valve 10 is closed or opened to the atmosphere. Next, the control means switches the opening direction of the three-way valve 21 to the valve 22 side, and opens the valve 22 to supply the gas in the gas storage unit 9 into the airtight storage container 3. By supplying the gas, the inside of the storage container 3 is pressurized, and the molten metal 2 in the container is discharged through the hot water piping 5 (flowing in the direction of arrow L). At this time, since the molten metal 2 passes through the foreign matter removal filter 6, the foreign matter in the molten metal is captured by the filter 6. Thereby, the foreign material in the molten metal is removed, and a clean molten metal is discharged. Since the molten metal passes upward from the lower side of the filter 6 in FIG. 4, the trapped foreign matter adheres to the filter surface 6 a on the side in contact with the molten metal in the storage container 3, and the eyes of the filter. Dive into.

In order to prevent clogging of the foreign matter removal filter 6 and to clean the molten metal by bubbling, the gas supplied into the hot water discharge pipe 5 is an inert gas (N ₂ , Ar) or the like is used, but the present invention is not limited to this form. For example, the following form may be used.
Air in the atmosphere is used as the gas supplied to the hot water piping 5. For this purpose, instead of the gas supply means 8, an air separation device (for example, described in Japanese Patent Application Laid-Open No. 2006-150395) that takes in air in the atmosphere and separates it into nitrogen gas and oxygen gas is provided. The air separation device includes a separation device for separating the taken-in air into nitrogen gas and oxygen gas, a nitrogen gas delivery device for delivering nitrogen gas separated by the separation device, and a delivery device for delivering the separated oxygen gas. An oxygen gas delivery device is provided. By sending nitrogen from the nitrogen gas delivery device into the hot water supply pipe 5, the same effect as in the above embodiment can be obtained. Further, by sending oxygen from the oxygen gas delivery device, it is possible to burn the chip oil slide, which is a factor of product quality deterioration, and to improve the product quality.

It is a figure which shows one form of the purification apparatus of the filter clogging prevention apparatus and metal melt which concerns on this invention. It is a figure which shows a mode that a foreign material is removed with a filter at the time of molten metal tapping with the apparatus which concerns on this invention. It is a figure which shows a mode that the foreign material removal filter is backwashed with the supplied gas by the apparatus which concerns on this invention. It is a figure which shows another form of the filter clogging prevention apparatus which concerns on this invention, and the purification apparatus of a molten metal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filter clogging prevention device and purification apparatus of molten metal 2 Molten metal 3 Storage container 5 Piping for hot water (molten flow path)
6 Foreign matter removal filter
7 Piping opening / closing means (channel opening / closing means)
8 Gas supply means 9 Gas storage part 10, 22 Valve 11 Foreign material 21 Three-way valve

Claims (2)

Piping for discharging molten metal in a storage container including a melting furnace or holding furnace;
A foreign matter removal filter attached to a portion of the pipe extending into the storage container;
A pipe opening / closing means provided in a portion of the pipe downstream of the position where the foreign matter removal filter is provided with respect to the flow direction of the hot water;
A filter clogging prevention device and metal comprising gas supply means provided in a portion of the pipe between a position where the foreign matter removing filter is attached and a position where the pipe opening / closing means is provided Molten metal purification device. A filter clogging prevention method and purification of molten metal, wherein the foreign matter trapped in the foreign matter removal filter is backwashed using the filter clogging prevention device and molten metal purification device according to claim 1 and the metal melt is purified. A method,
After stopping the discharge of hot water downstream from the pipe opening and closing means by closing the pipe opening and closing means,
Operate the gas supply means to a gas supply state,
The gas supplied from the gas supply means is sent in the direction of the foreign matter removal filter through the pipe, passed from the downstream side to the upstream side of the foreign matter removal filter, and discharged into the storage container. A method for preventing clogging of a filter and a method for purifying a molten metal, wherein the foreign matter trapped on the surface on the container side is back-washed and the molten metal in the storage container is cleaned by bubbling the released gas.

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