JPH11293359A - Melting of metallic vanadium or/and metallic vanadium alloy, and its casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melting method and a casting method which can easily obtain a metallic V or/and a metallic V alloy having low oxygen concn. at a reduced cost. SOLUTION: To metallic V containing at least oxygen as impurity or/and an alloy consisting essentially of metallic V, one or more kinds of metals among rare earth elements (IIIb group) of Y, La, Ce, as the like, are added as a deoxidizer in a vacuum induction melting furnace equipped with a split type water- cooling copper mold 4. Under vacuum of 133.322×10-<3> -10-<4> Pa or in an atmosphere replaced with an inert gas of Ar or the like, after once attaining the vacuum, melting of the metallic V is executed. As a raw melting material, metallic vanadium containing >=1000 ppm oxygen is used and melted, and on the other hand, a deoxidizer of a quantity corresponding to two or more times of the oxygen concn. to the whole melting quantity is added in the vacuum melting furnace and simultaneously melted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melting metal vanadium and / or metal vanadium alloy having a low oxygen concentration, and a casting method for obtaining an ingot of metal vanadium and / or metal vanadium alloy having a low oxygen concentration.

[0002]

2. Description of the Related Art In recent years, demand for metal electrodes and the like is expected for metal vanadium (hereinafter, vanadium is referred to as V) by utilizing its features. However, metal V itself is 19
Since it has a very high melting point of 10 ° C., it is difficult to dissolve in a conventional melting method using a refractory crucible because impurities are mixed in from the crucible material. Therefore, conventionally, it has been manufactured by the method described below. V oxide + Al203 → Thermite reaction → Metal V (1) → EB
Melting → high purity metal V (2)

The metal V of the above (1) has a very large amount of impurities,
Further, since the oxygen concentration is high, it is difficult to use it as it is. Therefore, this is melted by EB (abbreviation of electron beam) and purified to a high degree. However, in EB melting, only the surface can be heated and the molten metal pool is shallow, so that alloying cannot be performed and uniform quality due to segregation and the like can be obtained. There is a problem that things cannot be done.

[0004] However, as described above, at present, it is impossible to dissolve non-contaminant by using other dissolving methods instead of removing impurities in the V raw material. Of these impurities, oxygen is the most important of the impurities present in the raw material when considering, for example, the case of being used for a secondary battery. As a deoxidation method for reducing the oxygen content in V, the following method has been proposed so far.

That is, the method disclosed in JP-A-6-28128 is a deoxidation method in which calcium metal and an oxide of a high melting point metal are mixed and dissolved. Although this method is considered to be effective, since the melting method is melting using a normal refractory crucible, there is contamination from the crucible material as described above. Therefore, this method provides a very impurity-rich metal (ie, the metal V (1)).
The level is at a limit, and it is impossible to obtain a metal V and / or metal V alloy having an oxygen concentration of 1000 ppm or less, which is the target of the present applicant.

On the other hand, as a prior art relating to the deoxidation method, there is a known technique disclosed in Japanese Patent Application Laid-Open No. 6-184658. This relates to a method of deoxidizing using a rare earth element while melting a high melting point metal such as Ti or a Ti alloy in a cold crucible melting furnace. However, this prior art does not describe deoxidation of metal V or metal V alloy at all, and merely discloses another deoxidation method that does not suggest any content suggesting this. .

[0007]

As described above, at present, metal V and / or metal V having an oxygen concentration of 1000 ppm or less are present.
The present invention has been made in view of the fact that alloys are not easily obtained, and it is therefore an object of the present invention to easily and inexpensively provide a metal V or / and metal V alloy having a low oxygen concentration. An object of the present invention is to provide a melting method and a casting method that can be obtained.

[0008]

The present invention has the following configuration to achieve the above object. That is, the invention of claim 1 according to the present invention relates to a method in which metal vanadium containing at least oxygen as an impurity and / or an alloy containing metal vanadium as a main component is mixed with Y, Y in a vacuum induction melting furnace using a split type water-cooled copper mold. A method for dissolving a metal vanadium or / and a metal vanadium alloy, wherein one or more metals selected from rare earth elements (IIIb) such as La and Ce are added as a deoxidizing agent and are simultaneously dissolved. is there.

Further, according to a second aspect of the present invention, in accordance with the first aspect, the inside of the vacuum induction melting furnace is set to a vacuum atmosphere of 133.322 × 10 ^-3 to 10 ^-4 Pa. A method of melting a metal vanadium and / or a metal vanadium alloy, wherein the metal vanadium and / or the metal vanadium alloy is melted while being kept in one of an atmosphere in which the pressure is once reduced to a vacuum and replaced with an inert gas such as Ar.

Further, the invention of claim 3 according to the present invention relates to the invention of claim 1 or 2 wherein the raw material to be dissolved is
While dissolving it using metal vanadium containing 2,000 ppm or more of oxygen, an amount corresponding to a concentration of twice or more of the oxygen concentration with respect to the total amount of the dissolution as the deoxidizing agent is added into the vacuum induction melting furnace and simultaneously dissolved. And melting the metal vanadium and / or metal vanadium alloy.

Further, the invention of claim 4 according to the present invention relates to the invention of claim 1 or 2, wherein 1
While dissolving this using metal vanadium containing 000 ppm or more of oxygen, an amount (Ce etc.) satisfying the following equation in relation to the oxygen concentration [% O] with respect to the total amount of the dissolution as the deoxidizing agent is obtained by the vacuum induction. A method for melting metal vanadium and / or a metal vanadium alloy, wherein the metal vanadium and / or the metal vanadium alloy are simultaneously added and melted in a melting furnace. Note: ln [% O]> 4.98 + ln [Ce etc.]

A fifth aspect of the present invention is directed to a melting step by the melting method according to the first, second, or fourth aspect, and a casting step performed by mold casting or continuous casting immediately after the melting step. And obtaining an ingot of metal vanadium or / and metal vanadium alloy having an oxygen concentration of 1000 ppm or less.

[0013] The invention of claim 6 according to the present invention is characterized in that the melting step by the melting method of the invention of claim 3 and the casting step performed by mold casting or continuous casting immediately after this melting step are 500 ppm or less. A casting method characterized by obtaining an ingot of metal vanadium or / and metal vanadium alloy having an oxygen concentration of:

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 conceptually shows a main structure of a melting and casting process according to an embodiment of the present invention.

In the melting method of the present invention, the melting is performed in a vacuum induction melting furnace 2 using a split type water-cooled copper crucible 4 (hereinafter referred to as cold crucible). By adding a rare earth metal (III) such as lanthanum La, yttrium Y, cerium Ce and the like in an amount twice or more the oxygen concentration contained in the raw material and simultaneously dissolving the same, oxygen in the molten metal such as YO or CeO is added. It is a method of forming an oxide and evaporating or floating on the surface of the molten metal, or evaporating and separating.
amount of rare earth metal (III) such as a, Y, Ce [Ce et
c.] with respect to the oxygen concentration [% O] contained in the raw material at a value that satisfies the following formula: In [% O]> 4.98 + ln [Ce etc.]. The gist of the present invention lies in a method in which oxygen in the molten metal is converted into an oxide such as YO or CeO to evaporate, float on the surface of the molten metal, or evaporate and separate.

In the molten metal V obtained by this method, the oxygen concentration can be controlled within the range of 1000 ppm to 100 ppm, and an ingot is obtained as it is by continuous casting such as casting by a crucible tilting or drawing. As a result, the intended purpose can be achieved. The atmosphere inside the vacuum induction melting furnace 2 at this time is 133.
A vacuum of 322 × 10 ⁻³ to 10 ⁻⁴ Pa or an atmosphere of an inert gas such as Ar is desirable.

The melting and casting method according to the embodiment of the present invention is performed by the melting and casting means shown in FIG. The metal V and / or the metal V alloy as the raw material to be melted m is stored in a supply bucket 10 in the raw material chamber 1 and a predetermined amount is supplied to a water-cooled copper crucible 4 in a vacuum induction melting furnace 2 disposed immediately below. You.

In the vacuum induction melting furnace 2, a water-cooled copper crucible 4 formed by assembling a plurality of water-cooled copper segments into a vertical cylindrical shape to form a split-type water-cooled copper mold is surrounded by the outer periphery of the crucible 4. And a bottom tapping nozzle 7 connected to the bottom of the water-cooled copper crucible 4, and a vacuum exhaust means 6 is connected to a vacuum chamber of the vacuum induction melting furnace 2. ing.

Material to be melted m supplied to water-cooled copper crucible 4
Is melted by reducing the pressure in the vacuum chamber by the vacuum evacuation means 6 and heating by the induction coil 5. At this time, the inside of the water-cooled copper crucible 4 is added with a deoxidizing agent as described above or at 133.322 × 10 ^−3. Vacuum of 10 ^-4 Pa or A
The condition with the atmosphere of the inert gas such as r is maintained.

The metal V and / or the metal V alloy, which is the raw material m to be melted in the water-cooled copper crucible 4, is taken out from the bottom tapping nozzle 7 and supplied to, for example, the mold 3 in a casting chamber provided immediately below. After casting and casting, it is taken out of the mold 3 as an ingot 9.

V is 191 of the high melting point metals.
The melting point is very high at 0 ° C., and it is almost impossible to lower the impurity concentration by the melting method using a normal refractory crucible because impurities are mixed into the molten metal from the crucible material.

The inventors of the present invention have conducted various studies, and found that the method of melting in the skull 8 using the melting material itself based on the experimental results of melting using a cold crucible vacuum induction melting furnace, Has been found to be the only method for obtaining metal V and / or metal V alloys with a low concentration of. That is, since the split type water-cooled copper is used as a crucible, the molten metal solidifies at the place where it comes into contact with the water-cooled copper, and its solidified shell (skull: the same material as the molten metal)
This is because it substitutes for the inner wall of the crucible, and because induction heating is performed using a very high-frequency power supply, the molten metal is constantly stirred vigorously, and uniform casting without segregation is performed. Lumps are easier to get. Thus, by adopting a melting method using a cold-crucible vacuum induction melting furnace, it is possible to obtain an ingot having a uniform structure without dissolving and further having no segregation.

Further, the dissolution atmosphere at this time was examined.
Fruit, 133.322 × 10^-3-10 ^-FourMelted under vacuum of Pa
It is best to understand or replace with Ar atmosphere
And found the present invention. However, in this method
Produces high purity metal V alloys, especially low oxygen concentrations.
It is difficult to do.

Next, as a prerequisite for the deoxidation method, it is necessary to be able to easily remove the product by the deoxidation method because work in a vacuum chamber is impossible. Furthermore, the deoxidizing agent used must be an element that does not cause any problem even if it remains in V. As a result of examining a material that satisfies such conditions and facilitates the reaction and separation of the product at a high temperature, a deoxidizing agent usually used, Al or alkaline earth metal, Effect was not obtained. Therefore, as a result of various studies, the present inventors have found that deoxidation by a rare earth element and removal of a deoxidized product are possible, and arrived at the present invention.

This is because it has been confirmed that the rare earth element turns the oxide generated at the melting temperature of the metal V into a gas or evaporates. Therefore, since the atmosphere is in a substantially vacuum state, most of the generated oxides go out of the furnace, so that there is very little contamination of the molten metal. However, oxides that partially remain on the surface of the molten metal can be separated while leaving the oxides on the surface by pouring the molten metal from the bottom of the furnace or continuously casting the bottom.

The weight of the deoxidizing agent required at this time is determined by the concentration of oxygen contained in the raw material and the compound generated by the deoxidizing reaction. For example, if the raw material contains 10000 ppm of oxygen, the amount of Mg required to remove up to 1000 ppm is as follows. The atomic weight is O: Ce =
16: 140, 0.9 × from the resulting compound CeO ₂
140/16 × 2 = added Mg requiring 3.9 (mass%)
Quantity. In La, O: La = 16: 139, more product compound _{CeO 2, 0.9 × 139/16} × 2 =
3.9 (mass%).

Actually, 10 to 20 in consideration of the yield and the like.
It is a preferable means to add a large amount by about%. Further, as a result of further study, it has been found that, when Ce is mainly used among oxygen and rare earth elements in the metal V, there is a relationship represented by the following formula. Therefore, Ce
Is mainly added, a metal V having a desired oxygen concentration can be obtained by adding an amount satisfying this relationship. ln [% O]> 4.98 + ln [Ce]

Further, when Al or the like is contained as an impurity in the raw material when melting in a cold crucible vacuum induction melting furnace, it is necessary to add a rare earth element. It is possible to use. In addition, it is also preferable to remove the remaining additive element by evaporating it by performing vacuum evacuation again after the deoxidizing step and removing it.

In the present invention, deoxidation is carried out by adding one or more rare earth elements as a deoxidizing agent simultaneously or after meltdown from a molten metal containing oxygen as an impurity, and separating and removing oxygen. Thus, production of high-purity metal V can be achieved. Here, the casting method is not particularly limited. For example, any of "casting to mold by tilting" or "continuous casting" is possible. However, when considering the oxide remaining in a small amount, it can be said that continuous casting is preferable.

With respect to the embodiment of the present invention, the change over time of the oxygen concentration in the V melt is as shown in FIG.
With the addition of m (Misch metal: metal containing a large amount of rare earth), the oxygen concentration in the molten V decreases with time,
It becomes almost 0 in 80 minutes. On the other hand, the relationship between oxygen and Ce in the V melt when Ce was mainly used as a deoxidizing agent, as shown in FIG. 3, was that 0.01% of Ce was added and the oxygen concentration was 10,000 ppm. 1% Ce for V melt
The addition can reduce the oxygen concentration to 100 ppm.

[0031]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The present invention is not limited by the following examples, and various modifications can be made without departing from the spirit of the invention described above and below. Included.

[Example 1] Melting raw material: 6 mass% of metal V + Mm, simultaneous melting Raw material V composition: V: 96.0, Mo: 0.003, Al: 0.64, Si: 0.02, FeO : 0.015, C: 0.007, O: 2.7 All mass% Melting furnace: φ200 cold crucible vacuum induction melting furnace Melting condition: Atmosphere Vacuum (~ 133.322 × 10 ^-4 Pa) Output: 350 ~ 380 kw Analysis method: The oxygen concentration was analyzed by ICP emission spectroscopy, and the dissolved metal V was compared with the raw material. As a result, as shown in Table 1 below, the oxygen concentration in metal V was as low as 300 ppm.

[Table 1] * Similar results were obtained when the addition method was changed.

[Example 2] Melting raw material: 100 mass% of metal V + 3 mass% of Mm as raw material, simultaneous melting Melting furnace: φ200 cold crucible vacuum induction melting furnace Melting condition: atmosphere Vacuum (~ 133.322 × 10 ^-4 Pa) Output: 350-380 kw Analysis method: The oxygen concentration was analyzed by ICP emission spectroscopy, and the dissolved metal V was compared with the raw material. As a result, as shown in Table 2 below, the oxygen concentration in metal V was as low as 900 ppm.

[Table 2]

[Example 3] Melting raw material: 4% by mass of metal V + 100% + Mm, simultaneous melting Melting furnace: φ200 cold crucible vacuum induction melting furnace Melting condition: Atmosphere vacuum (~ 133.322 × 10 ^-3 Pa) Output: 350 kW Analysis method: The oxygen concentration was analyzed by ICP emission spectroscopy, and the dissolved metal V was compared with the raw material. As a result, as shown in Table 2 below and FIG. 2, the oxygen concentration in the metal V was as low as 300 ppm.

[Table 3]

[0035]

The present invention is embodied in the form described above and has the following effects. That is,
ADVANTAGE OF THE INVENTION According to this invention, it is possible to refine | purify low-purity metal vanadium by making high purity, especially oxygen concentration 1000 ppm or less. In addition, oxygen can be removed without causing contamination of the molten metal. Further, the production of high-purity metal vanadium is possible.

[Brief description of the drawings]

FIG. 1 is a conceptual structural diagram of a melting and casting process according to an embodiment of the present invention.

FIG. 2 is a graph showing the change over time in the oxygen concentration in a V melt.

FIG. 3 is a diagram showing the relationship between oxygen and Ce in a V melt.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Material room 2 ... Vacuum induction melting furnace 3 ... Mold 4 ... Water-cooled copper crucible 5 ... Induction coil 6 ... Vacuum exhaust means 7 ... Bottom tapping nozzle 8 ... Skull 9 ... Ingot 10 ... Supply bucket m ... Material to be melted

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hitoshi Ishida 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Research Institute

Claims (6)

[Claims] A metal vanadium containing at least oxygen as an impurity and / or an alloy containing metal vanadium as a main component is mixed with a rare earth element such as Y, La, or Ce in a vacuum induction melting furnace using a split water-cooled copper mold. A method for dissolving a metal vanadium or / and a metal vanadium alloy, wherein one or more metals selected from IIIb) are added as a deoxidizing agent and simultaneously dissolved. 2. The furnace of the vacuum induction melting furnace, wherein 133.
Dissolving by holding in a vacuum atmosphere of 322 × 10 ⁻³ to 10 ⁻⁴ Pa or in an atmosphere in which the pressure is once reduced to the above-mentioned pressure and then replaced with an inert gas such as Ar. Item 4. The method for dissolving metal vanadium or / and metal vanadium alloy according to item 1. 3. A metal vanadium containing oxygen of 1000 ppm or more is dissolved as a raw material to be dissolved, and the amount corresponding to a concentration of at least twice the oxygen concentration with respect to the total amount of the dissolved metal is used as the deoxidizing agent. The method for melting a metal vanadium and / or a metal vanadium alloy according to claim 1, wherein the metal vanadium and / or the metal vanadium alloy are added in a melting furnace and melted at the same time. 4. While dissolving metal vanadium containing oxygen of 1000 ppm or more as a raw material to be dissolved, an oxygen concentration [% O] with respect to the total amount of the dissolved metal is used as the deoxidizing agent.
3. A metal vanadium or / and / or metal alloy according to claim 1 or 2, wherein an amount satisfying the following equation [Ce etc.] is added into the vacuum induction melting furnace and melted simultaneously.
And a method of melting a metal vanadium alloy. Note: ln [% O]> 4.98 + ln [Ce etc.] 5. A melting step of the metal vanadium and / or the metal vanadium alloy according to claim 1, 2 or 4, and a casting step performed by a mold casting or a continuous casting immediately after the melting step, so that 1000 ppm is obtained.
A method for casting a metal vanadium or / and / or a metal vanadium alloy, comprising obtaining an ingot of a metal vanadium or / and a metal vanadium alloy having the following oxygen concentration. 6. A method for melting a metal vanadium or / and a metal vanadium alloy according to claim 3 and a casting step immediately after the melting step by a mold casting or a continuous casting, whereby an oxygen concentration of 500 ppm or less is obtained. A method for casting a metal vanadium or / and / or a metal vanadium alloy, comprising obtaining an ingot of a metal vanadium or / and a metal vanadium alloy.