JP2949222B1 - Refining method of molten metal - Google Patents

Abstract

[PROBLEMS] To purify and purify a substance by removing inclusions and impurities. SOLUTION: When completely melting titanium, for example, when melting titanium, a molten flux such as calcium fluoride and a rare earth metal is present between a floating molten metal and a water-cooled crucible to purify the molten metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for providing a stable levitation molten state and for purifying a levitation molten metal by using a cold crucible type levitation melting apparatus.

[0002]

2. Description of the Related Art As conventionally known, a molten metal melted using a cold crucible type flotation melting apparatus is free of impurities from a crucible and can be melted without lowering the purity of a raw material to be melted. There are features. Also,
This cold crucible type complete levitation melting system uses high-frequency induction heating, so that the levitation molten metal is well mixed and works well. There is also a feature that can be performed.

[0003]

However, the cold crucible type flotation melt having the above-mentioned excellent characteristics is provided.
Even in solution, the removal of inclusions and impurities <br/> elemental contained in the molten metal is not easy in terms of purity of the molten metal. In other words, in the melting method using the conventional cold-crucible flotation melting apparatus, since there is no contamination from the water-cooled copper crucible, it can be melted without lowering the purity of the melted raw material, and other water-cooled crucibles can be used. Unlike dissolution method had, although the material of the uniform component has the characteristic that said obtained, since no refining effect, because it was not possible to create a soluble Kaihara fee or purity of the material .

Therefore, the invention of this application solves the above-mentioned problems of the prior art, and effectively removes inclusions and impurity elements contained in the levitation molten metal in the cold crucible type levitation melting. It is an object of the present invention to provide a new method capable of purifying and purifying molten metal.

[0005]

SUMMARY OF THE INVENTION The claimed invention is to solve the above problems, first, as the first aspect, cold
Provided is a method for purifying a molten metal, characterized in that a molten flux is present between a buoyant molten metal and a water-cooled crucible when being melted by a crucible-type levitation melting apparatus. Also,
This application relates to the invention 1 described above, wherein the method for purifying molten metal according to claim 1 wherein solid or liquid non-metallic inclusions in the floating molten metal are transferred to the molten flux as invention 2, and the method for floating the molten metal as invention 3 as invention 3. Provided is a method for purifying a molten metal for transferring a dissolved impurity element in a molten metal.

Further, the present application relates to the above inventions 1 to 3, as invention 4, a method of purifying any one of the above, wherein the molten metal is titanium or an alloy mainly containing titanium, and as invention 5, a flux of fluorine. According to a sixth aspect of the present invention, there is provided any one of the above-described purification methods for performing deoxygenation, wherein the above-mentioned purification method, which is at least one of calcium oxide and a rare earth metal, is used.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the invention of this application will be described in more detail. In the method of the first aspect, the cold
Melting the metal or alloy in Shiburu type levitation melting apparatus, for holding the riff Lux by the heat transfer from the molten metal in a molten state. In this case, the flux, cold comes from the beginning
It may be placed in a water-cooled crucible of a shivable type flotation melting apparatus or added after flotation melting. The added state, remains solid, or any of a pre-molten state
May be.

[0008] In most cases, the inorganic compound used as the flux has lower electric conductivity than metal, so that at the frequency of induction heating for melting the metal, almost no eddy current flows and the crucible is not heated. There is no buoyancy force. Therefore, when the temperature becomes higher than the melting point of the flux due to the heat transfer from the molten metal, the material is melted and exists between the water-cooled crucible and the molten metal.

[0009] In portion in contact with the water-cooled crucible, and solidified with heat removal from the water-cooled crucible, forms a solid film, in many cases, due to the low thermal conductivity of the flux, the thickness of the solid film is extremely thin no longer Most of the flux is in a molten state. Also, due to the electromagnetic stirring action of the molten metal, a flow is generated on the surface of the molten metal . For this reason, also occurs stirring of the flux itself due to the action of the viscosity of the molten flux.

[0010] When performing a levitation dissolved in this melting method, does not occur contact with the water-cooled crucible according to the fluctuation of the floating molten metal itself at all, and therefore, stable levitation lysis Ri'm in comparison with the flotation dissolved in the case where there is no melting flux State can be achieved . The method of Invention 2 is a method for cold
Le-type flotation melter molten flux is interposed between the flotation molten metal and the crucible in a process for the purification by migrating non-metallic inclusions in the solid body or liquid in the flotation molten metal.

The inclusions (mostly non-metallic inclusions such as oxides, sulfides, carbides and nitrides) in the levitation molten metal are :
Since the electric conductivity is lower than that of metals and alloys, eddy currents do not easily flow. Therefore, inclusions tend to collect on the outside of the flotation molten metal receiving many rather difficulty receiving the electromagnetic force, the electromagnetic force in the frequency range of the high frequency power supply used in the flotation dissolution. The thus inclusions moves outside surface of the floating lifting the molten metal by causing migration in the molten hula <br/> click scan with inclusions and affinity than the molten metal, inclusions from flotation molten metal you remove.

The inclusions are preferably melted in a molten flux, but may be suspended in a liquid or solid state in the molten flux. Component of the melt flux, melting point than the melting point of the flotation molten metal rather low, and when the elaborate dissolved inclusions, to adjust the temperature lower than the temperature at that time component range as coercive.

[0013] The method of Invention 3 is a method of transferring impurity elements dissolved in the floating molten metal to a molten flux interposed between the floating molten metal and the crucible in a cold crucible type floating melting apparatus . it is a method for purifying molten metal you removed from the molten metal. Flotation molten metal is to be agitated strongly by electromagnetic force caused by high-frequency induction, less loss of concentration of the impurity element in the vicinity of the surface of the molten metal, and since the majority of the surface of the flotation molten metal contact with the molten flux, an impurity element the transition to the molten flux is the result to be carried out Ku ten minutes speed.

[0014] Unlike most smelting furnaces, because it does not use the refractory material, the reaction between the refractory and flux required rather Na consider, can freely select the type and composition of the flux. Therefore, conventionally difficult or impossible to use
The use of high flux refining performance becomes possible was also achievement of the impurity element removal rate is high, it becomes both possible to manufacture ultra-high purity metal material.

[0015] Next, with reference to FIG. 1 of a specific configuration. Is composed of a plurality of metal segments divided by the slits (3) (2), the upper surface is opened, to blockage under surface
That, a water-cooled metal crucible having a water-cooling mechanism (8) (1),
An induction coil (7) through which a high-frequency current flows from a high-frequency power supply (10) constitutes a cold crucible type flotation melting apparatus.

[0016] Figure 2 shows the state before flotation dissolution, melting material (4A) in one of the cylindrical shape is, the flux (5A) is that of the particulate is used. Melting material (4
A) can, if the eddy current is sufficiently flowing magnitude at high frequency induction heating, plate-like, rather may be a granular flux (5
A) may be a powder. When a high-frequency current flows through the coil (7), an eddy current flows through the melting material (4A), and the temperature rises. What this dissolved material (4A) of the temperature on the wake on temperature, heat transfer from the flux (5A) temperature itself melting material (4A)
To rise . At temperatures above the melting point, flux
(5A) flows and becomes a molten flux (5) as shown in FIG. On the other hand, melting material (4A) is by levitation force from a water-cooled crucible (1), the crucible (1) and Hise' Furejo state in flotation molten metal (4). Molten flux (5)
Because the eddy currents also becomes melted hardly flows, not work is floating lift, between the flotation molten metal (4) and a water-cooled crucible (1), present in the form as is shown in Figure 3. I
Therefore, the molten flux (5), a water-cooled crucible (1)
In contact with, crucible good in heat removal from (1) Lil jar (1)
An extremely thin solidified film (6) is formed at the contact portion with the solid. This becomes a protective film, any components, the use of flux composition, a water-cooled crucible by melting a flux (5)
Erosion of (1) does not occur.

The floating molten metal (4) may shake due to fluctuations in the power supply or the like, and may come into contact with the crucible wall. However , the molten metal (4) comes into contact with the crucible (1) due to the presence of the molten flux (5). rather, stable levitation dissolved to achieve
Is done . A floating lifting the molten metal (4), from the crucible (1)
A compressive force acts due to electromagnetic force . For this reason , the inclusions in the levitation molten metal (4) apparently include the levitation molten metal (4).
Force directed from the center axis of the surface-out work, migrate to the surface of the flotation molten metal (4). Thus inclusions migrate to the surface of the floating lifting the molten metal (4) is supplemented in the molten flux (5), to migrate. When using an general refractory crucible, separation of inclusions is carried out at the interface of the crucible (1) and molten flux (5), as compared to the area (cross-sectional area of the crucible), melted flux Since the contact area between (5) and the molten metal (4) can be increased, the effect of separating and removing inclusions is large. The properties of flux
Does not react with the levitation molten metal (4),
It is desirable to select a material having a large power.

The floating molten metal (4) is very strongly stirred by high frequency induction. The molten flux (5) is strongly stirred with the molten metal. For this reason, the decrease in the concentration of the impurity element near the interface between the molten metal (4) and the molten flux (5) is small on both the molten metal (4) side and the molten flux (5) side, and the interface is actively renewed. Therefore, the transfer of the impurity element to the molten flux (5) is performed sufficiently quickly. Further, as described above, the effect of obtaining a large contact area between the flux and the molten metal is also added,
The effect of separating and removing impurity elements is large, and a high-purity metal material can be manufactured.

Furthermore, unlike the ordinary refining furnace, it does not use refractory materials, the reaction between the refractory and flux required rather Na consideration, component-to sufficiently decrease the activity of the impurity element in the flux since the flux composition can be used, achievement of the impurity element removal rate becomes high, allowing the production of ultra-pure metal material. More specifically, the above inventions 4 to 6 can be exemplified. Molten metal, an alloy mainly containing titanium (Ti) or titanium,
Flux, and calcium fluoride (CaF _2), is one or more rare earth metals. This removes oxygen
Excellent effect that is Ru obtained.

When a flux composed of calcium fluoride and a rare earth metal is used for titanium or its alloy, the amount of the flux added is determined from the viewpoint that deoxygenation is performed while suppressing incorporation into titanium or its alloy. As a general rule, it is appropriate to set the rare earth metal to 1/10 or less as a weight ratio with respect to titanium or its alloy (titanium component), and more preferably 1/20 to 1/100. Also, for calcium fluoride, the weight ratio was 1 /.
A range of 20 to 1/50 is considered. As for the ratio with the rare earth metal, the range of the rare earth metal / calcium fluoride (weight ratio) is generally from 1 to 1/5.

As for the composition of the flux, for example, use of alkaline earth metal fluorides such as magnesium fluoride and strontium fluoride, or alkaline earth metal chlorides such as calcium chloride and magnesium chloride, etc. Can be considered. Various kinds of rare earth metals are used, but addition of Misch metal (MM) as a mixture as well as single addition of Ce, La, Y, Sm, Nd and the like is effective.

An embodiment will be described below.

[0023]

(Example 1) 450 g of titanium and 40 g of calcium fluoride whose oxygen concentration was adjusted were inserted into a water-cooled steel crucible having an inner diameter of 60 m and a depth of 85 mm, and levitation melting was performed. After melting both titanium and calcium fluoride, 10 g of cerium metal was added to the molten titanium. The result is shown in FIG. The horizontal axis represents the elapsed time after cerium addition, and the vertical axis represents the oxygen concentration in titanium and the cerium oxide concentration in calcium fluoride. The cerium oxide generated in the molten titanium by the addition of cerium metal migrated from the molten titanium to the molten flux, and oxygen as an impurity element was removed from the molten titanium. (Example 2) In Example 1, 10 g of mesh metal (MM) was added instead of cerium metal.

FIG. 5 shows the relationship between the initial oxygen concentration, the amount of deoxidation, and the rare earth (REM) metal concentration in titanium. The deoxygenation amount increases almost in proportion to the initial oxygen amount for both Ce and MM, and the REM remaining in titanium decreases.
When the initial concentration is 1%, in Ce, 29% of the added amount is MM
44% is used for deoxygenation.

It can be seen that the addition as MM is more effective for deoxygenation than metal Ce alone.

[0026]

By using the method of the invention of the present application, more stable levitation and melting, which could not be obtained by the conventional levitation and melting, can be performed, and furthermore, a higher purity and higher purity metal material than the conventional method can be provided. It is possible to do.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating the configuration of a flotation melting apparatus.

FIG. 2 is an exploded perspective view showing an example of a state before flotation melting.

FIG. 3 is an exploded perspective view illustrating a state during melting.

FIG. 4 is a view showing an example in which oxygen in molten titanium is transferred to and removed from molten flux by addition of cerium metal according to the method of the present invention.

FIG. 5 is a diagram showing an example of deoxidation of titanium by adding mesh metal (MM).

[Explanation of symbols]

 Reference Signs List 1 water-cooled metal crucible (cold crucible) 2 metal segment divided in the circumferential direction 3 slit 4 floating molten metal 4A melting material 5 molten flux 5A flux 6 solidified film 7 induction coil 8 water cooling mechanism 10 high frequency power supply

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C22B 9/16 C22B 34/12 103

Claims (6)

(57) [Claims] 1. A method for refining a molten metal, wherein a molten flux is present between a buoyant molten metal and a water-cooled crucible when being melted by a cold crucible type levitation melting apparatus. 2. The method for refining molten metal according to claim 1, wherein solid or liquid nonmetallic inclusions in the floating molten metal are transferred to the molten flux. 3. The method for purifying a molten metal according to claim 1, wherein the impurity element dissolved in the floating molten metal is transferred to the molten flux. 4. The method according to claim 1, wherein the molten metal is titanium or an alloy mainly containing titanium. 5. The method according to claim 1, wherein the flux is at least one of calcium fluoride and a rare earth metal. 6. The purification method according to claim 1, wherein deoxygenation is performed.