JP2010014398A - Dissolution apparatus and dissolution method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To employ moving plasma with excellent energy efficiency in a dissolution method in which metal powder is dissolved and separated from a mixture of a metal salt and metal powder, and a dissolution apparatus used for the method. <P>SOLUTION: A inner face member 15 comprising a second metal is inserted to cover side faces and upper edges of the side faces of a bath 10 comprising a first metal. Then, the mixture 1 comprising the metal salt and the metal powder is introduced into a mixture introduction region 16 of the bath 10 partitioned by a skimmer 13, and maintaining a state that the whole of the mixture 1 has been dissolved using plasma 19a, two layers comprising an upper layer (molten salt 6 where the metal salt has been molten) and a lower layer (molten metal 7) are formed as a result of a difference in specific gravity. The formation of a molten salt layer which is an insulator formed by the solidification of the molten salt 6 on the inner face of the bath 10 is prevented by maintaining the temperature of the portion of the inner face member 15 brought into contact with the molten salt 6 not lower than the melting point of the molten salt 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a melting apparatus used for separating the metal constituting the metal particles from the mixture of the metal particles and the metal salt, the melting apparatus capable of stable operation using a transfer type plasma having excellent thermal efficiency, And a dissolution method using the same.

As an industrial method for producing metal Ti, a crawl method in which TiCl ₄ is reduced with Mg is generally used. According to this method, a high-purity product can be produced. However, since the generated Ti powder settles in an aggregated state and is difficult to recover outside the reaction vessel, the operation must be performed in a batch mode. Further, since TiCl ₄ is supplied in liquid form from above to the liquid surface of the molten Mg liquid in the reaction vessel, and the reaction is performed only near the liquid surface of the molten Mg liquid, avoiding a decrease in the utilization efficiency of TiCl ₄ , In order to avoid local exotherm accompanying the reaction, the feed rate of TiCl ₄ is limited. As a result, the manufacturing cost increases and the product price becomes very high.

Therefore, many researches and developments have been made on methods for producing metal Ti other than the crawl method. For example, in Patent Document 1, a molten metal salt of CaCl ₂ (hereinafter, also simply referred to as “molten salt”) is held in a reaction vessel, and metal Ca powder is supplied into the molten salt from above, to obtain a molten salt. A method is described in which Ca is dissolved therein, TiCl ₄ gas is supplied from below, and dissolved Ca and TiCl ₄ are reacted in a molten salt of CaCl ₂ . However, metallic Ca powder is extremely expensive, and in addition, highly reactive Ca is very difficult to handle, and this method cannot be established as an industrial metallic Ti production method.

Therefore, the inventors of the present invention need to reduce TiCl ₄ with Ca in order to industrially establish a method for producing metal Ti by Ca reduction, and economically use Ca in molten salt consumed in the reduction reaction. In addition to utilizing Ca produced by electrolysis of molten CaCl ₂ , a method of circulating and using this Ca, ie, the “OYIK method (Oic method)” was proposed (Patent Documents 2 and 3). reference).

Patent Document 2 describes a method in which Ca is generated and replenished by electrolysis, and molten CaCl ₂ with an increased Ca concentration is introduced into a reaction vessel and used to generate Ti particles by Ca reduction. Furthermore, a method of effectively suppressing back reaction accompanying electrolysis by using an alloy electrode (for example, Mg—Ca electrode) as a cathode is shown. Back reaction refers to the reaction between Ca in the molten salt and Cl ₂ generated by electrolysis when the molten salt from which Ti has been separated in the separation step is returned to the electrolytic cell, and back reaction occurs. , Current efficiency decreases.

  Patent Document 4 describes a method for producing Ti based on the OYIK method. As a method for separating Ti from a molten salt containing Ti particles produced by a reduction reaction, first, Ti is precipitated by centrifugal sedimentation in a high-temperature decanter. A method is described in which the grains are separated from the molten salt, and then the Ti grains are heated and melted by plasma irradiated from a plasma torch in a separation tank to remove the molten salt adhering to the Ti grains. The molten Ti is poured into a mold and becomes an ingot.

U.S. Pat. No. 4,820,339 JP 2005-133195 A JP 2005-133196 A International Publication No. 2007/105616 Pamphlet

  FIG. 1 is a diagram illustrating a configuration example of a conventional melting apparatus including a separation tank and a plasma torch. The hearth 10 as a separation tank is composed of a bottom surface 11 and a side surface 12, and the inside is divided into a mixture charging region 16 and a molten Ti region 17 by a skimmer 13. Both the regions 16 and 17 communicate with each other through a communication port 14 provided at the lower portion of the skimmer 13. The upper edge of the side surface 12 is set higher on the mixture charging region 16 side than the molten Ti region 17 side, and a groove for discharging a fluid such as a liquid (see FIG. (Not shown) is formed.

Above the hearth 10, there is disposed a plasma torch 19 that can swing, and can irradiate the mixture charging region 16 and the molten Ti region 17 with the plasma 19a. As the hearth 10, a water-cooled copper hearth is generally used. As the skimmer 13, ceramics such as Y ₂ O ₃ can be used.

Next, the operation in the hearth 10 will be described. A mixture of Ti particles generated by the reduction reaction and a molten salt containing CaCl ₂ (hereinafter referred to as solid-liquid mixture 1) is charged into the mixture charging region 16 of the hearth 10. The solid-liquid mixture 1 is irradiated with the plasma 19a from the plasma torch 19 and heated to the melting point of Ti or higher to bring the entire solid-liquid mixture 1 into a molten state. And this molten material is hold | maintained more than melting | fusing point of Ti, molten Ti is settled according to the specific gravity difference of Ti and molten salt, and it isolate | separates into the upper and lower layers (molten salt 6) and the upper and lower layers (molten Ti7). .

  When the solid-liquid mixture 1 is further charged, the liquid level rises in the mixture charging region 16 and the molten Ti region 17 in a state where the melt is separated into two layers, and melts from the upper edge of the side wall 12 on the molten Ti region 17 side. Salt begins to drain. When all the molten salt is discharged, the molten Ti region 17 is occupied by only the molten Ti7, and the molten Ti7 is discharged. On the other hand, when the liquid level rises also in the mixture charging region 16 and the liquid level becomes higher than the upper edge of the side wall 12 on the mixture charging region 16 side, the molten salt 6 starts to be discharged.

  Conventionally, as the plasma torch 19 used for dissolving the solid-liquid mixture 1 with the hearth 10, a plasma can be generated by the torch alone, and a non-migration type plasma torch that is easy to use has been used. However, since the non-transfer type plasma torch has a low thermal efficiency of 10% or less, the present inventors tried to dissolve the solid-liquid mixture 1 in the hearth 10 using the transfer type plasma torch having an excellent thermal efficiency of 30% or more. did. In the transfer type plasma torch, since it is necessary to energize between the torch and the object to be heated in order to generate plasma, a power source is disposed between the plasma torch 19 and the hearth 10. Since the solid-liquid mixture 1 is an electrical conductor containing Ti particles, it can be dissolved by plasma even when a transfer type plasma torch is used.

  However, plasma was no longer generated from the plasma torch 19 while melting was continuously performed. Further, although the plasma is generated for a while as the current flowing through the torch is increased when the plasma is not generated, the inner surface of the hearth is locally damaged. When this cause was examined, it was found that a metal salt layer in which the molten salt 6 was solidified was formed on the entire inner surface of the hearth 10.

  FIG. 2 is a view showing a state in which the metal salt layer 8 is formed on the inner surface of the hearth 10. Since the metal salt is an insulator, the metal salt layer 8 insulates the hearth 10 from the molten Ti7, and it is considered that the molten Ti7 is not energized and plasma is no longer generated. In addition, the local damage on the inner surface of the hearth 10 was caused by discharging and melting with the molten Ti 7 through the portion where the titanium was slightly exposed on the inner surface of the hearth 10 in the middle of the spreading of the metal salt layer 8. it is conceivable that.

The reason why the metal salt layer 8 is generated in this way is considered as follows. Since the hearth 10 is cooled with water, the temperature of the inner surface of the hearth 10 is kept below the melting point of Ti and CaCl ₂ even when the plasma 19a is irradiated in the state where the solid-liquid mixture 1 is accommodated. Therefore, even when the plasma is irradiated after the solid-liquid mixture 1 is dissolved by plasma, Ti and CaCl ₂ are solidified on the inner surface of the hearth 10, and the shell 4 made of a mixture of Ti and CaCl ₂ is formed. It is formed.

  The shell 4 contracts and expands because the temperature fluctuates due to factors such as the swing motion of the plasma torch 19. The molten salt 6 existing as an upper layer in the mixture charging region 16 flows into the gap between the inner surface of the hearth 10 and the shell 4 formed when the shell 4 contracts, and solidifies. While the shrinkage and expansion of the shell 4 are repeated, the portion into which the molten salt 6 flows gradually spreads on the inner surface of the hearth 10 to form the metal salt layer 8. Such a phenomenon may occur regardless of the ratio between the metal salt and the Ti grains in the solid-liquid mixture 1.

  Therefore, the present invention is a melting apparatus used for melting a mixture of metal particles and a metal salt to separate the metal constituting the metal particles, and can be stably operated using a transfer type plasma having excellent thermal efficiency. An object of the present invention is to provide a melting apparatus and a melting method using the same.

  In order to solve the above problems, the present inventors have examined a method for preventing the metal salt layer 8 from being formed between the inner surface of the hearth 10 and the shell 4. Is the portion where the shell 4 and the molten salt 6 in the upper layer are in contact with each other in the mixture charging region 16, and therefore the idea was to prevent the molten salt 6 from solidifying in this portion.

  The present invention has been made on the basis of the above-mentioned findings, and the gist of the present invention is the following (1) dissolution apparatus and the following (2) dissolution method.

  (1) A melting apparatus comprising a water-cooled hearth made of a first metal and having a side surface and a bottom surface, and a transition type plasma torch arranged to irradiate plasma on the inner surface of the water-cooled hearth, A melting apparatus, wherein an inner surface member made of a second metal is fitted so as to cover at least a side surface and an upper edge of the side surface among inner surfaces of the hearth.

  In the melting apparatus according to (1), it is preferable that the inner surface member also covers a bottom surface of the inner surface of the water-cooled copper hearth, and it is more preferable that the inner surface member is integrally formed. The first metal may be Cu and the second metal may be Ti. Ti may be metal Ti or alloy Ti.

  (2) In the melting apparatus according to (1), a melting method in which a mixture of a metal salt and a metal powder composed of the second metal is accommodated in the water-cooled hearth and is melted by plasma irradiated by the plasma torch. And the temperature of the part which contact | connects the said metal salt of the said inner surface member is maintained above melting | fusing point of the said metal salt, The melting method characterized by the above-mentioned. The metal salt at the time of charging into the water-cooled hearth may be in a solid state or a liquid state.

  In the melting method according to (2), the inner surface of the water-cooled hearth is divided into a plurality of regions by a skimmer, and the plurality of regions are respectively communicated by a communication port provided at a lower portion of the skimmer. The mixture is melted by plasma in one region of the water-cooled hearth and separated into two upper and lower layers by a specific gravity difference, a layer made of a molten metal in which the metal powder is dissolved and a layer made of a molten salt in which the metal salt is dissolved. The upper layer may be discharged from the upper part of the region and the lower layer may be discharged from the communication port. Thereby, it becomes possible to easily separate the second metal constituting the metal powder and the metal salt.

In the dissolution method according to (2), the metal salt may be CaCl ₂ and the second metal may be Ti. Ti may be metal Ti or alloy Ti. In the case of alloy Ti, contamination of the separated Ti alloy can be prevented by using the inner surface member as an alloy element constituting metal powder.

  According to the melting apparatus and the melting method of the present invention, by providing the inner surface member, it is possible to prevent a metal salt layer that is an insulator from being formed on the inner surface of the water-cooled hearth. Even when transitional plasma that requires energization between them is used, the metal constituting the metal particles can be stably separated from the mixture of the metal particles and the metal salt (molten salt). Moreover, since it is the same as the metal which isolate | separates the metal which comprises an inner surface member, the metal to isolate | separate is not contaminated.

It is a figure which shows the structural example of the conventional melt | dissolution apparatus. It is a schematic diagram when a plasma is no longer generated in a conventional melting apparatus. It is a figure which shows the structural example of the melt | dissolution apparatus concerning the 1st Embodiment of this invention. It is a figure which shows another structural example of the melting | dissolving apparatus concerning the 1st Embodiment of this invention, (a) provided the bottom plate, (b) covered the whole inner surface of the hearth with the integrated inner surface member. Is the case. It is a figure which shows the structural example of the melt | dissolution apparatus concerning the 2nd Embodiment of this invention. It is a figure which shows operation | movement of the melt | dissolution apparatus concerning the 2nd Embodiment of this invention, (a) is the state which is discharging | emitting molten salt, (b) is a figure which shows the state which is discharging | emitting molten Ti. .

<First Embodiment>
FIG. 3 is a diagram illustrating a configuration example of the melting apparatus according to the first embodiment of the present invention. The melting apparatus shown in FIG. 3 is the same as that shown in FIG. 1 except that the plasma torch is a transfer type and that an inner surface member is provided on the inner side surface of the hearth. ing.

  As shown in FIG. 3, the plasma torch 19 is a transition type, and a power source 20 is connected between the plasma torch 19 and the hearth 10. Since the hearth 10 and the solid-liquid mixture 1 are electrical conductors, when a voltage is applied by the power source 20 in a state where the solid-liquid mixture 1 is put into the hearth 10, plasma is generated between the plasma torch 19, the hearth 10, and the solid-liquid mixture 1. 19a occurs. In the present embodiment, instead of the solid-liquid mixture 1 made of molten salt and metal particles, a mixture of metal salt and metal particles in a solid state may be put into the hearth 10.

  Further, an inner surface member 15 made of Ti is fitted into the hearth 10 of the present embodiment so as to cover the upper edge and the inner surface of the side surface 12. By adjusting the thickness of the inner surface member 15 and the degree of adhesion with the hearth 10, etc., the amount of heat conduction between the hearth 10 and the inner surface member 15 is adjusted, and the solid-liquid mixture 1 is dissolved by irradiating the plasma 19a. The temperature of the surface of the inner surface member 15 that is in contact with the molten salt 6 can be equal to or higher than the melting point of the metal salt. Hereinafter, the exposed inner surface of the hearth 10 and the exposed surface of the inner surface member 15 when there is no container (the surface that contacts the molten salt 6 of the inner surface member 15 when the inner surface of the hearth 10 is not exposed). Collectively, it is called the inner surface of Hearth 10.

  Thereby, Ti solidifies on the inner surface of the hearth 10 to form the shell 4, and the molten salt 6 existing as an upper layer in the mixture charging region 16 is formed in the gap formed between the inner surface of the hearth 10 due to the shrinkage of the shell 4. Even if it flows, the molten salt 6 does not solidify. Therefore, the molten salt 6 that has flowed in is pushed back to the upper layer when the shell 4 expands. Further, when the shell 4 and the inner surface member 15 are integrated, there is no gap between the shell 4 and the inner surface of the hearth 10. Therefore, the metal salt layer 8 that is an insulator is not formed on the inner surface of the hearth 10.

  The upper edge of the side surface 12 of the hearth 10 is also covered with the inner surface member 15. Therefore, when the molten salt 6 existing as an upper layer in the mixture charging region 16 is discharged from the upper part of the mixture charging region 16 to the outside, the molten salt 6 does not enter between the hearth 10 and the inner surface member 15. The energized state during is maintained. Further, the lower portion of the inner surface member 15 is in contact with the molten Ti 7, and even if the molten Ti 7 enters and solidifies between the hearth 10 and the inner surface member 15, it becomes a part of the shell 4. The energized state between is maintained. Therefore, the energized state from the power source 20 to the molten Ti7 and the generation of the plasma 19a are stably maintained.

  Further, when the hearth 10 is shallow or when the output of the plasma torch 19 is large, when the heat of the plasma 19a spreads throughout the hearth 10 and the shell 4 is not formed, the molten salt 6 is solidified on the inner surface of the hearth 10. The molten salt 6 exists in the mixture charging region 16 as an upper layer because the specific gravity of the molten salt 6 is smaller than that of the molten Ti 7. Also in this case, the energized state of the molten Ti7 and the generation of the plasma 19a thereby are maintained.

  Therefore, as described above, stable separation of Ti and molten salt can be performed using a transfer type plasma torch having excellent thermal efficiency regardless of the presence or absence of a shell. Further, since the inner surface member 15 is made of Ti, it does not contaminate the separated Ti. In the case where the Ti grains are made of a Ti alloy, contamination of the separated Ti alloy can be prevented by making the inner surface member 15 from an alloy element constituting the Ti grains.

  FIG. 4 is a diagram illustrating another configuration example of the melting apparatus according to the present embodiment. In this embodiment, as shown to Fig.4 (a), in addition to the inner surface member 15 which covers the upper edge and inner surface of the side surface 12 of the hearth 10, you may provide the baseplate 15a which covers the inner surface of the bottom face 11 of the hearth 10. . Further, as shown in FIG. 2B, the inner surface member 15 may be integrated to cover the entire inner surface of the hearth 10 and the upper edge of the side surface 12. FIG. 4 shows a state where no shell is formed.

  In these cases, since the temperature of the inner surface of the hearth 10 including the bottom surface 11 can be equal to or higher than the melting point of the metal salt, even if the molten salt 6 may penetrate into the bottom surface after the shell is formed, Formation of a metal salt layer can be prevented, and Ti and molten salt can be separated more stably using a transfer type plasma torch.

<Second Embodiment>
FIG. 5 is a diagram illustrating a configuration example of a melting apparatus according to the second embodiment of the present invention. The melting apparatus shown in FIG. 5 is the same as that shown in FIG. 3 except that the hearth can be tilted and no skimmer is provided in the hearth, and substantially the same parts have the same reference numerals. Is attached.

  In the present embodiment, the solid-liquid mixture 1 charged in the hearth 10 is irradiated with plasma 19a from the plasma torch 19, and the solid-liquid mixture 1 is heated to the melting point of the molten salt or more and less than the melting point of Ti. Further, the solid-liquid mixture 1 is maintained at this temperature, and the molten salt 6 spreads on the bottom surface 11 of the hearth 10 so that the solid Ti 3 is dispersed in the molten salt 6. In the case where the solid Ti constituting the solid-liquid mixture 1 is bonded to the Ti particles by sintering or the like to form a porous lump, the Ti lump is exposed at the portion exposed from the molten salt 6 of the Ti lump. Molten salt or metal salt present in the internal gap is discharged to the outside.

  FIG. 6 is a diagram showing the operation of the melting apparatus according to the second embodiment of the present invention, where (a) shows a state in which molten salt is discharged, and (b) shows a state in which molten Ti is discharged. FIG. In FIG. 6, the plasma torch and the like are omitted. After making the molten salt 6 spread to the bottom surface 11 of the hearth 10, the hearth 10 is tilted so that the left side is lowered as shown in FIG. 6A, and the molten salt 6 is arranged at the lower left of the hearth 10. The molten salt container 21 is discharged, and the hearth 10 is in a state where solid Ti3 and a small amount of molten salt that has not been discharged exist. When the solid Ti3 is in the form of small particles or powders, the solid Ti3 discharged together with the molten salt 6 should be minimized by precipitating in the molten salt 6 and discharging the molten salt 6 without stirring. Can do.

  Subsequently, the hearth 10 is returned to the horizontal position, the solid Ti3 remaining in the hearth 10 is irradiated with the plasma 19a from the plasma torch 19 to dissolve the solid Ti3, and the hearth 10 is tilted so that the right side is lowered, and the molten Ti7 Is discharged into a Ti container 22 arranged at the lower left of the hearth 10. The solid Ti3 may be discharged after dissolving the whole, or may be sequentially discharged to the Ti container 22 while partially dissolving.

  Thereafter, the solid-liquid mixture 1 is again charged into the hearth 10, and dissolution of the solid-liquid mixture 1, discharge of molten salt, dissolution of Ti, and discharge of Ti are repeated. The solid-liquid mixture 1 may be charged after all the Ti has been discharged, or may be performed with some solid or liquid Ti remaining in the hearth 10. When the solid-liquid mixture 1 is introduced with a part of Ti remaining in the hearth 10, the solid-liquid mixture 1 is heated by the remaining high temperature Ti, which is excellent in terms of energy efficiency.

  Also in this embodiment, the temperature of the surface in contact with the molten salt or Ti of the inner surface member 15 while the solid-liquid mixture 1 or the solid Ti3 is dissolved is set to be equal to or higher than the melting point of the metal salt by the irradiation of the plasma 19a. it can. Therefore, even if Ti dissolved on the inner surface of the hearth 10 is solidified again to form a shell, and the molten salt flows into the gap formed between the shell and the inner surface of the hearth 10 due to the shrinkage of the shell, the inner member 15 By irradiating the plasma 19a so that the temperature of the surface in contact with the molten salt or Ti is equal to or higher than the melting point of the metal salt, solidification of the molten salt in the gap can be suppressed. Therefore, the metal salt layer 8 that is an insulator is not formed on the inner surface of the hearth 10, and the energized state between the power source 20 and the solid-liquid mixture 1 or solid Ti3 that is the object to be heated is maintained. The generation of 19a is stably maintained. Moreover, according to this embodiment, since a skimmer is not required, a melting apparatus can be made a simple structure.

  The molten Ti obtained using the melting apparatus of this embodiment contains a trace amount of molten salt. The molten Ti is moved to another hearth while maintaining the molten state, and the molten salt is removed, so that Ti can be purified. As the hearth for purification of Ti, the hearth of the first embodiment described above can be used.

  In FIG. 6, the direction in which the hearth 10 is tilted is different between when the molten salt is discharged and when Ti is discharged. However, when the molten salt container 21 and the Ti container 22 are movable, the directions in which the hearth 10 is tilted may be the same when they are located on the same side with respect to the hearth 10.

  In the present embodiment, instead of the solid-liquid mixture 1 made of molten salt and metal particles, a mixture of metal salt and metal particles in a solid state may be put into the hearth 10. Further, the height of the side surface of the hearth may be different on the left and right as shown in FIG. 3 and FIG. 4, or may be uniform as shown in FIG. 5 and FIG.

  In this embodiment, even if the inner surface member 15 is composed of a material that covers only the upper edge and inner surface of the side surface 12 of the hearth 10 and a bottom plate as shown in FIG. Thus, only the upper surface and the inner surface of the side surface of the hearth may be covered. In any case, since the temperature of the inner surface of the hearth 10 including the bottom surface 11 can be made higher than the melting point of the metal salt, the molten salt 6 may enter the bottom surface after the shell is formed. Even so, the formation of the metal salt layer between the inner surface member and the shell can be prevented, and Ti and molten salt can be separated more stably using the transfer type plasma torch.

  In order to confirm the effects of the metal melting apparatus and the melting method of the present invention, the following melting experiments were conducted and the results were evaluated.

<Test 1>
1. Melting conditions Using a melting apparatus shown in FIG. 4 (b), a raw material composed of a mixture of Ti grains and solid CaCl ₂ was separated into molten salt and molten Ti, and then a Ti ingot was cast. Table 1 shows the conditions of the manufacturing apparatus used. As shown in Table 1, the atmosphere in the chamber was an argon atmosphere. Further, in the example of the present invention, an integrally formed inner surface member that covers the entire inner surface of the hearth and the upper edge of the side surface is fitted into the water-cooled hearth, and the inner surface member is not used in the comparative example.

Table 2 shows the conditions of the raw material composition, weight, and dissolution current amount. Raw material, examples present invention, in both comparative examples, the Ti particles was 10 wt% and the CaCl ₂ mixture containing 90 wt% was used 5000～6000G.

  The dissolution current is a current that flows through the plasma torch, and both the inventive example and the comparative example were set so that the entire raw material was dissolved in the upper part of the hearth.

2. Test Results As shown in Table 3, the casting of the Ti ingot performed under the above conditions was evaluated using as an index whether or not Haas was worn and whether or not the melting could be resumed after the melting was interrupted.

  In both the comparative example and the example of the present invention, casting of a Ti ingot was possible. However, as shown in Table 3, although Haas wear did not occur in the inventive example, it occurred in the comparative example. This is because in the comparative example, the formation of a metal salt layer progresses between the inner surface of the hearth and the shell, and a local discharge occurs between the molten Ti and the exposed portion of the inner surface of the hearth. Conceivable.

  Further, in the example of the present invention, even after the melting was interrupted and the molten salt and the molten Ti were solidified, the plasma was generated from the plasma torch, and the melting could be resumed. However, in the comparative example, after the melting was interrupted, a metal salt layer was formed between the inner surface of the hearth and the shell, so that no plasma was generated from the plasma torch, and the melting could not be resumed.

Similar results were obtained when a mixture of Ti grains and liquid CaCl ₂ was used as a raw material.

<Test 2>
1. Dissolution condition A dissolution experiment similar to Experiment 1 was performed using the dissolution apparatus shown in FIG. Table 4 shows the conditions of the manufacturing apparatus used. In the present invention example, an integrally formed inner surface member that covers the entire inner surface of the hearth and the upper edge of the side surface was fitted into the water-cooled hearth, and the inner surface member was not used in the comparative example.

Table 5 shows the conditions of the raw material composition, weight, and dissolution current amount. The raw material was a mixture containing 40% by weight of Ti grains sintered in a porous lump and 60% by weight of CaCl ₂ in both the inventive example and the comparative example.

  Then, as shown in FIG. 6, the hearth is tilted to the left to discharge the molten salt, the tilt is moved to the right to discharge the molten Ti, and the operation of adding the raw material with the molten Ti remaining is performed by Repeated until all was dissolved. Plasma irradiation did not stop during this operation.

  In addition, using the hearth that has been subjected to the above continuous dissolution test, after the molten salt has spread to the bottom surface of the hearth, the plasma irradiation is interrupted, the Ti particles and the metal salt are solidified, and again Plasma irradiation was performed.

2. Test Results As shown in Table 6, the dissolution experiments were evaluated using the presence or absence of Haas wear and the possibility of resuming dissolution after dissolution interruption, as in Test 1 above.

  Molten Ti could be obtained in both the comparative example and the inventive example. However, as in Test 1, Haas wear did not occur in the example of the present invention, but occurred in the comparative example. This is because in the comparative example, the formation of a metal salt layer progresses between the inner surface of the hearth and the shell, and a local discharge occurs between the molten Ti and the exposed portion of the inner surface of the hearth. Conceivable.

  In addition, the restart after the melting of the raw material was interrupted was possible because plasma was generated from the plasma torch in the example of the present invention. However, in the comparative example, since a metal salt layer was formed between the inner surface of the hearth (the surface of the inner surface member) and the shell, plasma was not generated from the plasma torch, and dissolution could not be resumed.

  According to the melting apparatus and the melting method of the present invention, a metal salt layer that is an insulator is formed on the inner surface of the water-cooled hearth when the metal powder and the metal salt are melted to separate the metal constituting the metal particles. Therefore, even if a transfer type plasma torch that requires energization between the torch and the object to be heated is used, the separation operation can be performed stably.

  Therefore, the melting apparatus and the melting method of the present invention can be effectively used in the production of a metal obtained by reducing metal chlorides or the like in a molten salt obtained by mixing the metal powder with the molten salt. .

1: solid-liquid mixture, 3: solid Ti, 4: shell, 6: molten salt, 7: molten Ti,
8: Metal salt layer, 10: Hearth, 11: Bottom surface, 12: Side surface, 13: Skimmer,
14: communication port, 15: inner surface member, 15a: bottom plate, 16: mixture injection region,
17: Molten Ti region, 19: Plasma torch, 19a: Plasma, 20: Power supply
21: Molten salt container, 22: Ti container

Claims (7)

A melting apparatus comprising a water-cooled hearth made of a first metal having a side surface and a bottom surface, and a transitional plasma torch arranged so that plasma can be irradiated on the inner surface of the water-cooled hearth,
A melting apparatus, wherein an inner surface member made of a second metal is fitted so as to cover at least a side surface and an upper edge of the side surface of the inner surface of the water-cooled hearth.   The melting device according to claim 1, wherein the inner surface member also covers a bottom surface of the inner surface of the water-cooled hearth.   The melting apparatus according to claim 2, wherein the inner surface member is integrally formed.   The melting apparatus according to claim 1, wherein the first metal is Cu, and the second metal is Ti. The melting method according to any one of claims 1 to 4, wherein a mixture of a metal salt and a metal powder composed of the second metal is accommodated in the water-cooled hearth and is melted by the plasma irradiated by the plasma torch. Because
A melting method, characterized in that the temperature of the portion of the inner surface member in contact with the metal salt is maintained at or above the melting point of the metal salt. It is assumed that the inner surface of the water-cooled hearth is divided into a plurality of regions by a skimmer, and the plurality of regions are communicated with each other through a communication port provided at a lower portion of the skimmer,
The mixture is melted by plasma in one region of the water-cooled hearth and separated into two upper and lower layers by a specific gravity difference, a layer made of a molten metal in which the metal powder is dissolved and a layer made of a molten salt in which the metal salt is dissolved. The dissolution method according to claim 5, wherein the upper layer is discharged from the upper part of the region and the lower layer is discharged from the communication port. The dissolution method according to claim 5 or 6, wherein the metal salt is CaCl ₂ and the second metal is Ti.

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