JP2022067395A - Cold crucible melting furnace - Google Patents

Abstract

To provide a cold crucible melting furnace with a relatively simple structure, and allowing atomizing treatment of a confined type having higher efficiency of acquiring fine powder than a free fall type, capable of stably pulverizing bottom-tapped molten metal, and contributing to improvement of an operation cycle by reducing maintenance time.SOLUTION: A cold crucible melting furnace has a cylindrical crucible 1, a bottom plate 2 provided at a position of closing a bottom side of the crucible 1 and having a tap hole 21 at a prescribed part, a melting coil 3 arranged around the crucible 1 and a tapping coil 4 arranged around tap hole 21. Multiple water cooling copper bottom segments 5 electrically insulated from each other and arranged in the circumferential direction are employed as a bottom plate 2. Gas flow passages 57 for atomizing treatment are provided inside all or some of the water cooling copper bottom segments 5.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cold crucible melting furnace with a bottom hot water discharge method.

Conventionally, a cold crucible melting furnace has been known in which a melting object (metal to be melted) put into a crucible having a water cooling function is melted by an induction heating coil arranged on the outer periphery of the crucible. According to the cold crucible melting furnace, a skull (solidification part) formed on the water-cooled copper bottom provided at a position that closes the bottom side of the crucible is formed by an induction heating coil (hot water coil) arranged around the hot water outlet of the water-cooled copper bottom. It melts and the molten metal in the crucible can be discharged from the outlet.

The cold crucible melting furnace can melt active metals and refractory metals without lowering the purity, and in particular, it utilizes the hot water outlet hole itself formed directly in the water-cooled copper bottom as the hot water outlet of the water-cooled copper bottom. In this case, it is possible to discharge the molten metal with less impurities as compared with the embodiment in which a separate hot water discharge nozzle is provided on the water-cooled copper bottom. The present invention relates to an atomizing treatment in a cold crucible melting furnace, in particular, in which a gas is blown onto the molten metal that has been discharged after the hot water discharging step to generate fine powder.

For atomizing treatment, a freefall type (for example, see Patent Document 1 below) that atomizes the molten metal that has been discharged into a free space and then atomizes it with a gas nozzle provided below, and a hot water outlet that integrally has a gas nozzle that injects an inert gas. A confined type (for example, cold) in which the nozzle is placed below the bottom of the water-cooled copper, the jet gas from the gas nozzle generates a negative pressure state at the tip of the hot water nozzle, and atomizes while sucking the molten metal discharged from the hot water nozzle. It is roughly classified into the following Patent Document 2) which discloses a confined type nozzle that can be used by setting it in a simple molten metal reservoir instead of a crucible melting furnace. The applicant has mainly developed a cold crucible melting furnace to which a freefall atomize as shown in Patent Document 1 below is applied.

Japanese Unexamined Patent Publication No. 202-1234 Japanese Unexamined Patent Publication No. 5-202404

Here, comparing the above-mentioned freefall type and confined type regarding atomization, as mentioned in Patent Document 2, the amount of molten metal that can be atomized per hour, that is, atomization efficiency (efficiency for obtaining fine powder). In terms of points, the confined type, which can utilize negative pressure, is considered to be more advantageous than the freefall type, which cannot utilize negative pressure.

However, if the confined type as conventionally used is adopted, it is necessary to integrate the molten metal nozzle that directly supplies the molten metal to the space for atomization treatment and the gas nozzle that injects the inert gas. In addition to complicating the structure, the gas pipe connected to the gas nozzle may be heated by induction heating from the hot water coil, resulting in poor atomization.

In addition, of the water-cooled copper bottom that receives induction heating, the tip of the outlet (downstream end) has a slit, so the wall thickness is thin, and it is thought that melting damage due to induction heating and the flow of hot water is likely to occur. It can be a factor that causes instability of the hot water flow.

The present invention has been made by paying attention to such a point, and the main object thereof is to have a relatively simple structure without requiring a complicated structure for integrating a molten metal nozzle and a gas nozzle. To provide a cold crucible melting furnace that can execute confined atomization treatment, can stably pulverize the molten metal that has been discharged from the bottom, shorten the maintenance time, and contribute to the improvement of the operation cycle. There is something in it.

That is, the cold crucible melting furnace according to the present invention includes a tubular crucible, a bottom plate provided at a position that closes the bottom side of the crucible and having a hot water outlet at a predetermined position, and a melting coil arranged around the crucible. The bottom plate is an aggregate of multiple water-cooled copper bottom segments that are electrically isolated from each other and arranged in a circumferential direction, with a hot water coil arranged around the hot water outlet. It is characterized by forming a gas flow path for atomization treatment inside some water-cooled copper bottom segments.

In such a cold crucible melting furnace according to the present invention, a novel and useful technical technique that has never been conceived so far is to form a gas flow path inside the water-cooled copper bottom segment and perform atomization treatment. Based on the idea, it is necessary to install a gas pipe separate from the bottom plate by configuring the confined type gas atomizing treatment using gas for the molten metal discharged from the hot water outlet, and the molten metal nozzle and gas nozzle. It is no longer necessary to integrate the gas into an integrated structure, and the structure can be simplified in this respect. At the same time, since the gas flow path is formed inside the water-cooled copper bottom segment, it is connected to the gas nozzle, which has been a problem in the past. It is possible to avoid the situation where the gas pipe is heated by the induced heating from the hot water coil, and it is possible to prevent the atomization defect caused by the heating of the gas pipe. Furthermore, the cold crucible melting furnace according to the present invention is a confined type even at the tip of the hot water outlet, which has a nozzle shape with a relatively high risk of melting damage due to induction heating and hot water flow. By blowing gas near the tip of the hot water outlet, a cooling effect can be obtained and melting damage can be suppressed. Furthermore, in the case of the cold crucible melting furnace according to the present invention, the atomization efficiency can be improved by adopting the confined type capable of obtaining finer powder as compared with the freefall type. By obtaining the cooling effect around the hot water outlet, it is possible to prevent or suppress the formation of hot water dripping or drops around the hot water outlet at the end of the hot water discharge, and to carry out an appropriate hot water discharge treatment.

In particular, if the cold crucible melting furnace according to the present invention is provided with a protective tube that separates the space for arranging the hot water coil and the space below the hot water outlet and the space for atomizing treatment, the cold crucible melting furnace is provided. It is possible to prevent the molten metal discharged from the sprue, the fine powder after atomization treatment, the gas sprayed near the sprue, etc. from getting on or adhering to the hot water coil, and the induction heating treatment by the hot water coil. (Hot water control) can be performed appropriately.

In the cold creasable melting furnace according to the present invention, when the hot water outlet is a hot water outlet hole directly formed on the bottom plate, the degree of contamination of impurities is higher than that in the embodiment in which a separate nozzle is provided on the bottom plate. It is possible to discharge even less molten metal.

On the other hand, the cold creasible melting furnace according to the present invention also includes a configuration in which a hot water nozzle separate from the water-cooled copper bottom segment is applied as a hot water outlet. Even if the hot water outlet is a hot water nozzle that is separate from the water-cooled copper bottom segment, the gas blown near the hot water outlet through the gas flow path formed inside the water-cooled copper bottom segment obtains a cooling effect around the hot water outlet. It is possible to prevent or suppress the formation of water dripping or drops around the hot water outlet at the end of hot water discharge.

As described above, according to the present invention, since the gas flow path is formed inside all or a part of the water-cooled segments constituting the water-cooled copper bottom plate, the gas pipes and gas nozzles required for the confined type gas atomizing treatment are provided on the bottom plate. It is not necessary to separately provide it below, and it is possible to avoid complication of the structure and prevent the gas flow path formed inside the water-cooled copper bottom segment from being abnormally heated under the influence of induction heating. It is possible to provide a cold crucible melting furnace capable of preventing / suppressing the occurrence of atomization defects.

The figure which shows typically the whole structure of the cold crucible melting furnace which concerns on one Embodiment of this invention. Top view of the water-cooled copper bottom segment in the same embodiment. Overall overview view of the water-cooled copper bottom segment in the same embodiment. The figure which shows the water-cooled copper bottom segment in the same embodiment. The figure which shows one modification of the cold crucible melting furnace which concerns on the same embodiment corresponding to FIG. The figure which shows one different modification of the cold crucible melting furnace which concerns on the same embodiment corresponding to FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the cold crucible melting furnace X according to the present embodiment has a tubular water-cooled copper crucible 1, a water-cooled copper bottom plate 2 provided at a position that closes the bottom side of the crucible 1, and a periphery of the crucible 1. It is provided with a melting coil 3 arranged in the water-cooled copper bottom plate 2 and a hot water discharging coil 4 arranged around the hot water outlet 21 of the water-cooled copper bottom plate 2.

The crucible 1 is formed by joining a part or all of a vertically long water-cooled copper segment 11 having a partially arcuate cross section in the circumferential direction while being separated from each other by a slit. The insulating state between the water-cooled copper segments 11 adjacent to each other in the circumferential direction can be ensured by interposing an insulating member between the water-cooled copper segments 11 or by separating the water-cooled copper segments 11 from each other. With such a configuration, the water-cooled copper segments 11 constituting the crucible 1 are electrically insulated from each other, and the magnetic flux generated by the melting coil 3 which is an induction heating coil arranged around the crucible 1 is efficiently generated in the crucible 1. Can be introduced well. A melting power source (not shown) that outputs an alternating current for controlling melting is connected to the melting coil 3. Examples of the insulating member arranged between the water-cooled copper segments 11 include ceramic refractory materials such as alumina, zirconia, and yttria. Further, each water-cooled copper segment 11 has excellent electric conductivity and thermal conductivity, is strong against thermal shock, has necessary mechanical strength, and is skull Wa (see FIG. 1) by circulating a cooling medium through a water-cooled passage. It is formed of copper or a metal material such as chromium copper, beryllium copper, zirconium copper, chromium zirconium copper, and tellurium copper, which has a high thermal conductivity required for forming the above. In particular, in the case of a copper-based material, since the crucible 1 does not form an oxide when the crucible 1 is installed inside a vacuum chamber to dissolve the metal to be dissolved W in a vacuum atmosphere or a reduced pressure atmosphere, the metal oxide or the like is used. It is advantageous compared to refractory materials. Examples of the metal to be dissolved W include, in addition to titanium, a reactive metal made of zirconium, hafnium, chromium, niobium, tantalum, molybdenum, uranium, rare earth metal, thorium, or a metal selected from these alloys. .. The crucible 1 is cooled by circulating a refrigerant such as water in a refrigerant flow path (not shown) formed inside the water-cooled copper segment 11.

The bottom plate 2 is formed by arranging a plurality of water-cooled copper bottom segments 5 in a circumferential direction in a state of being electrically insulated from each other. The insulating state between the water-cooled copper bottom segments 5 adjacent to each other in the circumferential direction can be ensured by interposing an insulating member between the water-cooled copper bottom segments 5 or by separating the water-cooled copper bottom segments 5 from each other. .. In the present embodiment, a fan-shaped water-cooled copper bottom segment 5 obtained by dividing a disk into eight is applied. Like the water-cooled copper segment 11 constituting the rutsubo 1, each water-cooled copper bottom segment 5 has excellent electric conductivity and thermal conductivity, is strong against thermal shock, has the necessary mechanical strength, and has a cooling medium in the water-cooled passage. A material having the high thermal conductivity required to form Skull Wa (see FIG. 1) by circulating copper, or a metal such as chrome copper, beryllium copper, zirconium copper, chrome zirconium copper, tellurium copper, etc. It is made of material. A hot water outlet hole 2A, which is a hot water outlet 21, is formed in the central portion of the bottom plate 2 in which the water-cooled copper bottom segments 5 are arranged in the circumferential direction.

As shown in FIGS. 2 to 4, each water-cooled copper bottom segment 5 has a partially arcuate outer peripheral end surface 51 and a radial surface 52 extending linearly from a common center toward both ends of the outer peripheral end surface 51. The overall shape is defined by the pointed inner peripheral end surface 53 at which the radial surfaces 52 intersect, and the upward surface 54 and the downward surface 55. 4 (a) and 4 (b) are a cross-sectional view taken along the line AA and a view taken along the line B in FIG. 2, respectively.

The water-cooled copper bottom segment 5 of the present embodiment has a refrigerant flow path 56 and a gas flow path 57 inside. In the present embodiment, gas flow paths 57 are formed in the vicinity of the radial surface 52 of each water-cooled copper bottom segment 5, and two refrigerant flow paths 56 are provided at appropriate positions not overlapping the two gas flow paths 57. Is forming. Each of the refrigerant flow paths 56 extends radially from the circular water collecting channel 58 in a plan view set at a position closer to the outer peripheral edge of the water-cooled copper bottom segment 5 toward the outer peripheral end surface 51. The bottom plate 2 which is an aggregate of such a water-cooled copper bottom segment 5 is cooled by circulating a refrigerant such as water in a refrigerant flow path 56 formed inside the water-cooled copper bottom segment 5. Further, a recess 59 (notch) is formed in a predetermined region of the radial surface 52 excluding the tip 5T in order to improve the passage of magnetic flux (see FIGS. 3 and 4 (b)). The recess 59 is not essential and may not be provided if the magnetic flux is sufficient.

The water-cooled copper bottom segment 5 forms a hot water outlet hole element 5A constituting the hot water outlet hole 2A in the region near the inner peripheral end (pointed head 5T) including the inner peripheral end surface 53. In the present embodiment, tapered surfaces 54a and 55a inclined downward are formed on the upward surface 54 and the downward surface 55 of the pointed head 5T of the water-cooled copper bottom segment 5, respectively, and hot water is discharged from a predetermined region including these tapered surfaces 54a and 55a. The hole element 5A is formed. The upward surface 54 of the hot water hole element 5A is the surface that comes into contact with the molten metal Wb.

The gas flow path 57 extends in a straight line in a plan view along the radial surface 52 so that the upstream end 57a in the gas supply direction reaches the outer peripheral end surface 51 of the water-cooled copper bottom segment 5, while the downstream end 57b in the gas supply direction is reached. It reaches the downward surface 55 at a position close to the pointed head 5T (see FIG. 4A). Specifically, the gas supply direction in the gas flow path 57 so that the gas can be blown toward the target position which is a position slightly lower than the lower end of the hot water outlet 21 (the lower end of the inner peripheral end surface 53). The flow path in the vicinity of the downstream end 57b is set as an inclined flow path gradually downward. The inclined flow path is set to have a smaller flow path diameter than the flow path on the upstream side, and functions as an injection nozzle for injecting gas at a high pressure, and the downstream end 57b in the gas supply direction functions as a gas injection port. A gas supply mechanism (not shown) for supplying a gas (for example, an inert gas such as argon gas) is connected to the gas flow path 57. Specifically, the gas supply mechanism includes a gas supply source, a pipe connecting the gas flow path 57 to the gas supply source, a valve inserted in the pipe, and the like.

The bottom plate 2 formed by arranging such water-cooled copper bottom segments 5 in the circumferential direction has a hot water outlet 21 (a hot water hole 2A which is an aggregate of hot water hole elements 5A) in a central portion, and is a gas flow path. It integrally has an atomizing processing unit that blows the gas ejected from the gas injection port, which is the downstream end 57b of the 57 (gas nozzle) in the gas supply direction, to the target position set below the hot water outlet 21. The hot water outlet hole 2A has a funnel shape as a whole, and is a cylindrical straight portion whose diameter does not change over the entire axial direction under the inverted conical diameter expansion portion that expands in diameter as it approaches the upper end. Is a series of. In the present embodiment, since the water-cooled copper bottom segment 5 having a shape in which the pointed head 5T protrudes downward is applied, the lower end portion of the hot water outlet hole 2A of the bottom plate 2 protrudes downward from the other portions. become. The lower space S1 of the hot water outlet 21 is a hot water outlet space, and since the atomizing process is performed in this space, it is also an atomizing space. As is well known, the atomizing treatment is a treatment in which gas is blown onto the molten metal Wb that has been discharged to generate fine powder.

The cold crucible melting furnace X of the present embodiment is provided with a protective tube 7 in which a hot water discharge coil 4 which is an induction heating coil is arranged around the hot water outlet 21 and the arrangement space of the hot water discharge coil 4 is isolated from the atomizing space S1. There is. The protective tube 7 is a cylindrical member, is made of various refractories, ceramics such as BN, etc., the inner diameter thereof is set larger than the opening diameter at the lower end of the hot water outlet 21, and the outer diameter is set to the hot water discharge coil 4 It is set below the minimum inner diameter of. The upper end of the protective tube 7 is fixed in contact with the downward surface 55 of the bottom plate 2 by an appropriate means, and the protective tube 7 is positioned below the hot water discharge coil 4 in this fixed state. The height dimension of is set. Since the protective tube 7 is provided, it is possible to prevent / suppress the situation where particles such as molten metal Wb and fine powder flow are caught or adhered to the hot water discharge coil 4 during the atomizing process. A hot water discharge power supply (not shown) that outputs an alternating current for controlling hot water discharge is connected to the hot water discharge coil 4.

When the metal W to be melted in the rutsubo 1 is melted by the cold crucible melting furnace X having such a configuration, the melting power source is AC to the melting coil 3 which is an induction heating coil arranged on the outer periphery of the rutsubo 1. By supplying an electric current, an alternating magnetic field is generated around the melting coil 3, and the magnetic flux passes through the slit of the rutsubo 1 and penetrates into the inside of the rutsubo 1 to permeate the metal to be melted W and be covered. The molten metal W can be induced and heated. As a result, as shown in FIG. 1, the metal to be melted W melts from the surface side heated to the melting temperature to become the molten metal Wb, which flows down toward the bottom plate 2. Then, the molten metal Wb that has reached the bottom plate 2 is cooled and solidified by the bottom plate 2 and the crucible 1 that are maintained in an appropriate cooling state by flowing the refrigerant through the cooling flow path, and forms a cooled and solidified skull Wa. .. The hot water outlet 21 is plugged by this skull Wa, so that the dissolved material (melted water Wb) does not leak from the hot water outlet 21.

When a high-frequency current flows from the hot-water power supply device to the hot-water discharge coil 4 after the time when the material to be dissolved is sufficiently melted in the rutsubo 1, an alternating magnetic field is generated around the hot-water discharge coil 4 by this high-frequency current. This alternating magnetic field heats the surface of the metal to be dissolved W (skull Wa) solidified at the outlet 21 by generating an eddy current to thin the solidified layer. The thinning of the solidified layer makes it possible to discharge hot water, and the molten metal Wb in the crucible 1 can be discharged from the hot water outlet 21 (hot water hole 2A). In the cold crucible melting furnace X of the present embodiment, gas is injected from the downstream end 57b (gas injection port) of the gas flow path 57 in the gas supply direction at substantially the same time as the molten metal Wb is started to be discharged from the hot water outlet 21, and the hot water outlet. The molten metal Wb discharged from 21 is collided with the gas discharged from each gas injection port at a target position to be crushed and solidified, and a gas atomizing treatment for making fine particles is executed.

In the cold crucible melting furnace X according to the present embodiment, since the gas flow path 57 is formed inside the water-cooled copper bottom segment 5, the gas flow path 57 is exposed to the magnetic field formed by the hot water discharge coil 4 during the atomizing process. It is possible to avoid the situation of being induced and heated.

Further, at the time of this atomizing treatment, the molten metal Wb may be blown up or the fine powder may be rolled up in the atomizing space S1 (hot water discharging space). Since it is isolated from the hot water, the hot water coil 4 is not contaminated by the blow-up of the molten metal Wb or the roll-up of fine powder. Further, it is possible to avoid a situation in which the molten metal Wb is blown up to the hot water discharge coil 4 and the fine powder is rolled up to generate an electric discharge.

As described above, according to the cold crucible melting furnace X according to the present embodiment, the gas flow path 57 is formed inside the water-cooled copper bottom segment 5, and the atomizing space S1 below the hot water outlet 21 is formed through the gas flow path 57. Since it is configured to perform gas atomization treatment to generate fine particles by spraying gas, it is not necessary to arrange a separate gas pipe or gas injection nozzle under the bottom plate 2, while simplifying the structure. Since the confined atomizing process can be performed and the gas flow path 57 is formed inside the water-cooled copper bottom segment 5, the gas pipe connected to the gas nozzle, which has been a problem in the past, can be used. It is possible to avoid the situation where the gas is heated by the induced heating from the hot water coil, and it is possible to prevent the atomization defect caused by the heating of the gas pipe. Furthermore, in the case of the cold crucible melting furnace X according to the present embodiment, even at the tip end portion (downstream end portion in the hot water discharge direction) of the nozzle-shaped hot water outlet 21 in which there is a relatively high possibility of melting damage due to induction heating and hot water flow. By making it a confined type, gas can be blown near the tip of the hot water outlet 21 to obtain a cooling effect, which can suppress melting damage and also cause dripping around the hot water outlet 21 at the end of hot water discharge. It is possible to prevent or suppress the formation of drops and carry out an appropriate hot water discharge treatment. If the molten metal drips or drops adhere to the hot water outlet 21 at the end of hot water discharge, the skull cannot be taken out after the operation, and it takes a lot of time for maintenance, and the water-cooled copper bottom plate 2 is damaged or the operation cycle is reduced. However, according to the cold crucible melting furnace according to the present embodiment, these problems can be solved.

In addition, in the cold crucible melting furnace X according to the present embodiment, the downstream end 57b in the gas supply direction of the gas flow path 57 functions as a gas injection port for ejecting gas diagonally downward, and such a gas injection port. Since the bottom plate 2 having a plurality of gases arranged along the circumferential direction is applied, fine particles can be efficiently generated by the gas discharged from each gas injection port, and the area around the hot water outlet 21 is cooled. Can be performed efficiently, and the flow of hot water can be stabilized and the atomizing efficiency can be improved.

In particular, since the cold crucible melting furnace X according to the present embodiment uses the hot water outlet hole 2A directly formed in the bottom plate 2 as the hot water outlet 21, this is compared with the embodiment in which a separate dedicated nozzle is provided. It is possible to discharge the molten metal Wb with a smaller degree of contamination of impurities.

The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the hot water outlet has a shape in which the downstream end (tip) in the hot water direction protrudes downward, but as shown in FIG. 5, the downstream end (tip) in the hot water direction is downward. A hot water outlet hole 2A having a shape that does not protrude into the hot water can be applied.

Further, in the above-described embodiment, an embodiment in which a hot water outlet hole directly formed in the bottom plate is applied as a hot water outlet is exemplified, but as shown in FIG. 6, a hot water nozzle N separate from the bottom plate 2 is used for hot water discharge. The sprue 21 can also be configured.

The hot water nozzle N is a funnel-shaped member as a whole, and has a cylindrical shape whose diameter does not change over the entire axial direction under the inverted conical diameter-expanded portion that expands as it approaches the upper end. A series of straight parts can be mentioned. The hot water discharge nozzle N is provided by inserting it through a through hole (a hot water discharge hole in the above-described embodiment) provided in the substantially center of the bottom plate 2, and a hot water discharge flow path of the metal to be dissolved W is formed inside the rutsubo 1 and the hot water discharge nozzle N. Similar to the bottom plate 2, it is an aggregate in which segments formed separately are spliced together, and the inside of the hot water nozzle N (hot water flow path) is provided by the hot water discharge coil 4 (induction heating coil for hot water discharge) arranged on the outer periphery of the hot water discharge nozzle N. ) Can be configured to introduce an induced magnetic field. The through hole of the bottom plate to which the hot water nozzle is attached may have a funnel-shaped internal shape or a simple cylindrical shape.

In the above-described embodiment, the embodiment in which the gas flow path is formed inside all the water-cooled copper bottom segments is exemplified, but the embodiment in which the gas flow path is formed only inside some of the water-cooled copper bottom segments may be used. .. The length, diameter, number, and shape of the gas flow path can be changed and selected as appropriate.

The number of water-cooled copper bottom segments (number of divisions) constituting the bottom plate can be appropriately changed.

The present invention also includes a cold crucible melting furnace in which the rutsubo, the bottom plate, each coil, and the atomizing space are arranged in the chamber, and the inside of the chamber can be set as a vacuum space.

In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 ... Crucible 2 ... Bottom plate 21 ... Hot water outlet 2A ... Hot water hole 3 ... Melting coil 4 ... Hot water coil 5 ... Water-cooled copper bottom segment 57 ... Gas flow path 7 ... Protective pipe N ... Hot water nozzle X ... Cold crucible melting furnace

Claims (4)

With a tubular crucible,
A bottom plate provided at a position that closes the bottom side of the crucible and having a hot water outlet at a predetermined location,
The melting coil arranged around the crucible and
It is equipped with a hot water outlet coil arranged around the hot water outlet.
The bottom plate is formed by arranging a plurality of water-cooled copper bottom segments electrically insulated from each other in a circumferential direction.
A cold crucible melting furnace characterized in that a gas flow path for atomization treatment is formed inside all or part of the water-cooled copper bottom segment. The cold crucible melting furnace according to claim 1, further comprising a protective tube that is below the hot water outlet and separates the space for performing the atomizing treatment from the space for arranging the hot water coil. The cold crucible melting furnace according to claim 1 or 2, wherein the hot water outlet is a hot water outlet hole directly formed in the bottom plate. The cold crucible melting furnace according to claim 1 or 2, wherein the hot water outlet is a hot water nozzle separate from the water-cooled copper bottom segment.

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