JPH0814009B2 - Ultra low oxygen titanium production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention solves various problems that occur in the deoxidation reaction of titanium based on the thermodynamic consideration of titanium.
It is the development of ultra-low oxygen titanium production and mass production type direct deoxidation method for titanium molded products.

According to the method of the present invention, it is possible to directly deoxidize a titanium molded product in which a large amount of oxygen is dissolved, without changing the shape of the titanium molded product, to manufacture an extremely low oxygen titanium product. Since a large amount of extremely low oxygen titanium produced is excellent in ductility, it is possible to produce an ultrafine titanium wire, an ultrathin titanium film, a titanium sheet and the like by using this. These are products that can replace the conventional fields occupied by aluminum, such as aluminum foil, aluminum cans, and aluminum wires. According to the present invention, titanium products, which are superior in corrosion resistance and heat resistance to aluminum, can be widely used in the industrial world and contribute to the development of new material technology.

(Prior Art) Titanium has been used as a structural material for aircrafts and a corrosion-resistant container material in the chemical industry due to its characteristics of high toughness, light weight, and excellent corrosion resistance. The purity of commercially available industrial pure titanium is about 99 to 99.5 mass%, and impurities are roughly classified into interstitial impurities and substitutional impurities. The interstitial impurities refer to gas components such as oxygen, nitrogen and hydrogen, and carbon, and the substitutional impurities include metal elements such as iron, manganese and silicon. Many substitutional impurities improve the mechanical properties of titanium, or interstitial impurities have the effect of adversely affecting the hardness and tensile strength of titanium. In particular, if oxygen is contained as an impurity, the toughness at low temperature is deteriorated and the plastic working of titanium is hindered, so oxygen is an impurity element that requires extreme caution.

Since titanium has a very strong affinity with oxygen, it was impossible to directly remove oxygen in titanium and obtain titanium below 100 mass ppm even if a reducing agent such as magnesium or calcium was applied.

Titanium currently in mass production uses titanium tetrachloride (TiCl ₄ ) with reducing agents such as metallic magnesium and sodium.
Is produced by reducing. Since a reduction reaction that does not involve oxygen is used, in principle it is possible to produce titanium that does not contain oxygen, but contamination from raw materials, reaction vessels, etc. is unavoidable. The contained titanium is manufactured. There is no means for removing oxygen as an impurity dissolved in titanium in these industrial processes. For this reason, by controlling the pollution source, the amount of interstitial impurities has been reduced as much as possible, and ELI (Extra Low Inrters)
titial) Low oxygen concentration (200mass pp
Although high-grade titanium of m) is industrially produced, mass production of titanium of higher purity than this titanium was impossible by the conventional method.

It is possible to purify mass-produced titanium using the iodine method, and to produce high-purity (tens of mass ppm) titanium.
Since the thermal decomposition of titanium iodide gas is used, the reaction rate is slow and it is not suitable for mass production.

(Problems to be Solved by the Invention) In the above conventional method, there are some problems to be solved listed below.

(1) Since there is no effective deoxidizing agent for directly removing the impurity oxygen solid-dissolved in titanium, it has been costly to control the contamination source and remove impurities.

(2) When titanium less than 100 ppm is produced, it is impossible to obtain titanium with extremely low oxygen without changing the shape of the raw material because the raw material titanium is gasified again only by using the iodine method.

(3) Titanium scrap containing a large amount of oxygen could not be effectively removed of oxygen except by halogenating, refining and reducing it again as a raw material for titanium in the above-mentioned mass production method.

(4) The conventional method is not suitable for upsizing and continuous mass production because the process is complicated.

(Means for Solving the Problems) As a method for producing ultra-low oxygen titanium, the present inventors have used (A) deoxidation of oxygen in titanium with calcium, and (B) promotion of deoxidation reaction using a halide flux. ,
And (C) As a result of a synergistic effect such as a decrease in deoxidation limit caused by the decrease in the activity of by-product calcia due to the flux, the finding that it becomes possible to produce ultra-low oxygen titanium was earnestly studied. As a result of research, we have invented a manufacturing method based on the following combinations of steps.

The present invention has been achieved by elucidating the details of the following manufacturing principles, optimum application conditions of each method, a novel manufacturing apparatus, and a combination method thereof. The present invention relates to a method for producing a large amount without changing the temperature.

The present invention relates to calcium chloride having high purity with respect to oxygen,
Flux consisting of one or a mixture of two or more of barium chloride, magnesium chloride and calcium fluoride is heated and held in vacuum exhaust to sufficiently remove impurities such as water and carbon dioxide gas, and then put into a container together with titanium raw material. From the deoxidized titanium, the first step to put it in, the second step to heat it in the temperature range of 750 ℃ to 1200 ℃, to make the oxygen in the titanium deoxidize by causing calcium to act on the titanium in a gas liquid state. , Calcium chloride containing by-produced CaO, barium chloride, magnesium chloride, a flux consisting of one or a mixture of two or more of calcium fluoride is a mineral acid,
An extremely low temperature, which comprises a third step of dissolving and removing with any one or more selected from an organic acid, an aqueous solution of ammonium chloride, an aqueous solution of ammonium salt and an aqueous solution of sucrose, and taking out only deoxidized pure titanium. This is the step of the method for producing titanium oxide.

(Operation) The outline of the steps of the present invention will be described in the order of steps.

Step 1 Preparation of Flux A mixed flux of yttrium oxide added to anhydrous calcium chloride, barium chloride, magnesium chloride, calcium fluoride, or calcium chloride, which has a high purity with respect to oxygen, is heated and kept at 227 ° C for about 1 day in vacuum exhaust. It is necessary to sufficiently remove impurities consisting of water, carbon dioxide and put them in a container.

However, this step can be omitted depending on the purity of the raw material.

Second step In the step of heating the deoxidation reaction vessel to a temperature range of 750 ° C to 1200 ° C and causing calcium to act on the titanium in a gas or liquid state at high temperature to deoxidize oxygen in the titanium, activation of calcia is performed. Calcium vapor dissolves in the titanium soaked in the flux with a low amount, and the oxygen in the titanium which acts on the flux is removed.

3rd process refining A flux consisting of any one or a mixture of calcium chloride, barium chloride, magnesium chloride and calcium fluoride containing CaO by-produced from deoxidized titanium is mixed with a mineral acid or acetic acid aqueous solution. In the third step, the organic acid or the aqueous solution of ammonium chloride, the aqueous solution of ammonium salt and the aqueous solution of sucrose are dissolved and removed by any one or two or more kinds, the flux is dissolved and separated from titanium, and only pure titanium deoxidized is taken out is there.

The principle of the present invention is that by dissolving calcia (CaO), which is a by-product of the removal of oxygen in titanium by calcium, in a halide flux, it is possible to suppress the influence of calcia, which interferes with the reduction of the oxygen content, as much as possible. is important. The flux to be selected for this purpose is a stable liquid that does not decompose even in the presence of metallic calcium, and can reduce the activity of calcia by dissolving calcia or forming a stable compound with calcia. The flux must not reduce the activity of metallic calcium. The flux to which the process of the present invention can be applied is an alkaline earth halide such as calcium chloride, magnesium chloride, or calcium fluoride, and if these are set to be in a liquid state at the reaction temperature, they may be used alone or in a predetermined manner. It is also possible to mix and use in the ratio of. It is also possible to add yttrium oxide to these fluxes.

Raw material titanium immersed in such a flux is deoxidized by vapor evaporated from the metallic calcium liquid installed separately from the flux and titanium, but by-product calcia is dissolved in the flux and does not inhibit the deoxidation reaction. .
A pretreatment for removing moisture, carbon dioxide gas, etc. in the flux is necessary for more effective deoxidation. In addition, a wet process is required to recover titanium embedded in the flux after deoxidation. In addition to these, it is possible to produce ultra-low oxygen titanium of several tens mass ppm by combining a container and a method that do not mix oxygen from the atmospheric gas during the deoxidation reaction.

The method for producing ultra-low oxygen titanium of the present invention is carried out in a closed container. Metallic calcium, which is a deoxidizer, a flux that is essential for achieving an extremely low oxygen concentration, and titanium, which is a high oxygen concentration material, are enclosed in this container. The reason why metallic calcium is used as the deoxidizing agent here is to deoxidize titanium having a strong affinity for oxygen. Metallic calcium can contribute to the deoxidation reaction at a practical level reaction rate at 800 ° C. or higher. At such a deoxidizing temperature, a flux that satisfies the following conditions is applied.

(1) A stable liquid that does not decompose in the presence of metallic calcium.

(2) Dissolving calcia or making a stable compound with calcia. That is, it has a function of reducing the activity of calcia.

(3) A large amount of flux components do not dissolve in metallic calcium. That is, do not reduce the activity of metallic calcium.

 In the present invention, a flux made of the following materials is used.

Calcium chloride (CaCl ₂ ), barium chloride, (BaCl ₂ ) magnesium chloride (MgCl ₂ ), calcium fluoride (CaF ₂ ) These can be used alone, but they can be used to control the melting point and vapor pressure. You may mix and use it. These become liquid at a temperature at which they can react, and calcia can be dissolved in the liquid. A method of adding yttrium oxide to the above flux is also effective. This is because yttrium oxide reacts with calcia to form a stable complex oxide and can significantly reduce the activity of calcia.

(Example) In the examples of the present invention, high-purity anhydrous calcium chloride and anhydrous barium chloride alkaline earth halide fluxes were used in the present invention. In addition, an example of a flux obtained by mixing anhydrous calcium chloride and yttrium oxide will be described.

When using the above deoxidizers and fluxes, the reaction temperature should be 750 ℃ to 130 ℃ considering their chemical stability and reactivity.
Set to 0 ° C.

The chemical reaction in the sealed container is as follows. That is, at 750 ° C to 1300 ° C, calcium turns into a liquid and generates vapor, and the saturated vapor fills the container.
This calcium vapor dissolves in the flux, acts on titanium and reacts with oxygen in the titanium, deoxidizes even ultra-low oxygen titanium, transforms itself into calcia (CaO) and dissolves in the flux.

O (inTi) + Ca (1iq.in flux) = CaO (1iq.in flux) (1) The reaction described above uses flux to reduce the activity of the by-product calcia and effectively deoxidize it. Is aimed at. The ratio of the saturated solubility of calcia in the flux to the solubility of the actually dissolved calcia determines the activity of calcia, and this activity of calcia determines the oxygen deoxidation limit in titanium. Approximately 500 mass pp when titanium is deoxidized only with calcium without using flux.
Deoxidation up to about m is possible, but deoxidation below this is impossible in principle. In the method according to the present invention, the activity of calcia is reduced to 1/10 or less by using the flux, and
It is possible to produce titanium with an oxygen content below 0 mass ppm.

Example 1 Commercially available lumpy metal calcium is used as a deoxidizing agent. The flux is kept in vacuum at a temperature of about 227 ° C for about 1 day to remove impurities such as water and carbon dioxide.
This operation is necessary for effective deoxidation. As shown in FIG. 1, 100 to 100 g of flux 1 and 10 to 20 pieces of titanium 2 wire or lump containing various oxygen concentrations are used.
Individual pieces (about 0.1 to 2 g each) were placed in a titanium container 3, and these were placed in a stainless steel container 4 and sealed. The reducing agent calcium 7 was placed between the stainless steel container 4 and the titanium container 3. By installing the flux 1 and the reducing agent 7 with the titanium container 3 separated from each other, it is possible to prevent calcium impurities, which are impurities in calcium, from being mixed into the flux, and at the same time, to prevent moisture, which is a volatile impurity in the flux, from increasing during heating. Carbon dioxide can be combined with calcium to effectively use the flux. However, when using calcium with few impurities, you may install calcium with a flux and titanium in the said titanium container.

These were covered with an upper lid 6 and a bottom lid 5 made of stainless steel and placed in an alumina reaction tube 10. Next, the air in the reaction tube 10 is replaced with argon gas 11 and then heated, and this is heated to 750 ° C to 1 ° C.
It was kept in the temperature range of 200 ° C. for about 24 hours and then cooled. The air is exhausted to prevent the deoxidizer from being consumed by oxygen in the air and water in the sample and to prevent the formation of titanium nitride by nitrogen.

In order to carry out the deoxidation reaction completely, it is necessary and important to enhance the hermeticity of the reaction vessel containing the deoxidizing agent / flux and the raw material titanium, and it is necessary to pay particular attention.

For airtightness, after exhausting air, a method of connecting the stainless steel container to the outside air by a joining method such as welding is generally used, and this method can also be used for the present invention. However, in this method, the container must be destroyed in order to take out the sample or the like inside the container after the completion of the deoxidation reaction.

Therefore, in order to reuse the stainless steel container, the present invention has developed the method shown in FIG. For example, in the method described with reference to FIG. 1, the upper lid 6 and the bottom lid 5 are bolted to each other by sandwiching the container 4 and the thin bottom plate 18 made of stainless steel.
By crimping from above and below with the nut 17, the outflow of the deoxidizer and the inflow of oxygen gas and the like from the outside are prevented. After completion of the deoxidation reaction, the sample in the container can be easily collected by loosening the bolt.

Calcium present in excess acts as a liquid at the reaction temperature, fills the voids between the stainless steel plate 18 and the cup-shaped stainless steel container 4, and functions as a sealant. The titanium container 3 in the stainless steel reaction container is isolated by a molybdenum foil 13 so as not to react with the stainless steel. The container 3 that may come into contact with the titanium 2 as a raw material is made of titanium, but the reaction container 4 and the plate 18 are made of materials that do not react with metallic calcium and are stainless steel as long as they have heat resistance at the reaction temperature. It may be one.

Example 2 An example of obtaining a large amount of extremely low oxygen titanium using a horizontal electric furnace is shown in FIG. A stainless steel pipe 20 with one end closed was used as the reaction container. Raw titanium 21 and flux 22 were placed in a titanium crucible 23 in the container. When the crucible 23 directly contacts the stainless steel pipe 20, it reacts with each other and is compounded, so that the molybdenum foil 24, which does not react with both, is insulated from the crucible. The deoxidizer metal calcium 25 was installed in the pipe so as not to come into contact with titanium and flux. The stainless steel container is welded after exhausting air, so the inside of the container is vacuum or inert gas atmosphere.
26, which is cut off from the outside air. The stainless steel container 20 is heated to a predetermined temperature by an electric furnace in a vacuum or in an inert gas atmosphere 27.

After holding for a predetermined time, the electric furnace including the heating element 28 and the furnace core tube 29 is cooled, and the stainless pipe 20 is taken out from the furnace and cut to take out the sample in the tube. Since this method can prevent leakage of the deoxidizing agent, it has an advantage that the deoxidizing reaction can be completed as compared with the method shown in FIG.

Wet separation As a result of the above deoxidation reaction, the oxygen concentration in the raw material titanium decreases significantly. Since the cooled titanium is immersed in the flux, wet separation is performed in order to extract only titanium from the mixture of the titanium and the flux. When calcium chloride was used as the flux, the resulting mixture was put into an acetic acid aqueous solution, and the flux in which calcia was solid-dissolved was dissolved and separated to recover ultra-low oxygen titanium.

When barium chloride was used as the flux, titanium and flux were dissolved and separated in an acidic aqueous solution, for example, dilute hydrochloric acid aqueous solution, to recover titanium. When using calcium chloride + yttrium oxide mixed flux,
The flux was dissolved using an aqueous acetic acid solution, and metallic titanium was mechanically separated from the undissolved powder of yttrium oxide, a complex oxide with calcia, and the like.

Here, flux as a wet separation reagent for purification,
Industrially, the use of water is effective as the first-stage treatment for separating metallic calcium. However, since it is not possible to completely remove and purify with water alone, impurities that remain as a second-step treatment after the rough wet-separation with water as a first-step treatment are performed as described above. Need to be removed. For this purpose, in addition to mineral acids, organic acids such as acetic acid and oxalic acid can be used. In order to separate CaO, an ammonium salt aqueous solution, a sucrose aqueous solution or the like can be used in addition to the above acidic aqueous solution and ammonium chloride aqueous solution.

Example of analysis of oxygen contained Table 1 shows the results of oxygen analysis of titanium obtained as a result of the above chemical reaction (deoxidation reaction).

When using calcium chloride as the flux and deoxidizing with calcium vapor, the initial oxygen concentration was 1200,720,2, respectively.
Oxygen content of all titanium containing 00 mass ppm oxygen is 40 ~
It was deoxidized to 70 mass ppm. When deoxidized with barium chloride flux, titanium containing about 230 mass ppm oxygen was obtained, and with mixed flux of calcium chloride and yttrium oxide, about 180 mass ppm
Titanium containing oxygen was obtained. From the results shown in Table 1, it can be seen that the deoxidation limit of oxygen in titanium does not depend on the initial oxygen concentration and changes depending on the type of flux.

In addition, when deoxidizing titanium only with metallic calcium without using flux at 1000 ° C.
Deoxidation was possible only up to about 500 mass ppm. 500mass p
The oxygen concentration increased when titanium containing oxygen below pm was treated without flux. Even when flux is used, when the dehydration treatment of flux is insufficient, or when excess calcia is present in the flux from the beginning, such as when a large amount of calcia is contained as an impurity, the same Results are obtained, a few 100 mass pp
Only titanium containing m oxygen was obtained.

There is no change in the shape of titanium used as the starting material.
In the case of mass ppm, the Vickers hardness is 60 to 105 Hv (300 g
Load, 15 seconds), which was extremely low.

(Effects of the Invention) The extremely low oxygen titanium according to the present invention has not only the original lightweight and excellent heat resistance and corrosion resistance of titanium, but also high toughness, ductility and workability due to the low oxygen content. The present invention can provide a large amount of ultra-low oxygen titanium, which has been difficult to mass-produce and manufacturing cost is high, and has a great industrial advantage. Further, since titanium containing a large amount of oxygen can be reprocessed and converted into titanium having a low oxygen concentration, it can be applied to a method for recycling titanium scrap.

According to the production method of the present invention, metallic titanium having an arbitrary oxygen concentration can be deoxidized without changing its shape to produce titanium having extremely low oxygen toughness and excellent ductility. The titanium deoxidized by the method of the present invention can be easily processed into micron-order ultrafine wires, foils, sheets, plates, rods, tubes and the like, and thus can be used for food-grade aluminum foil, aluminum cans and the like. Even in fields such as chemical plants where severe corrosion resistance is required, lightweight titanium sheets with excellent heat resistance can be used. Further, it is also possible to locally deoxidize a titanium molded article containing oxygen by the production method of the present invention to partially change the mechanical properties.
For example, a titanium wire or plate that has become brittle due to a large amount of oxygen after being used for many years and has become unusable, or a composite thereof or the like is treated by the method of the present invention without breaking the original shape, There are great industrial advantages, such as the ability to reuse as it is.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a partial cross section of an apparatus for constructing a reaction container used in Example 1, and FIG. 2 is an explanatory view showing the configuration of a reaction container used in Example 2. 1 ... Flux 2 ... Titanium wires or lumps containing various oxygen concentrations 3 ... Titanium cup-shaped container 4 ... Cup-shaped stainless steel container 5 ... Stainless steel bottom lid 6 ... Stainless steel Top cover 7 ... Calcium metal that is a deoxidizing / reducing agent 8 ... Thermocouple for temperature measurement 9 ... Alumina tube for thermocouple protection 10 ... Alumina reaction tube with a round bottom closed end 11 ... High-purity argon Gas 12 …… Mullite core tube 13 …… Molybdenum foil 14 …… Mullite refractory brick 15 …… SiC heating element 16 …… Bolt 17 …… Nut 18 …… Stainless steel thin bottom plate 20 …… One end Closed stainless steel pipe 21 …… Titanium wires and lumps containing various oxygen concentrations 22 …… Flux 23 …… Titanium crucible 24 …… Molybdenum foil 25 …… Deoxidizing / reducing agent Calcium metal 26 ... Vacuum or inert gas Atmosphere 27 ...... vacuum or thermocouple 32 ...... rubber cap for protecting the alumina tube 31 ...... temperature measuring inert gas atmosphere 28 ...... SiC heating elements 29 ...... alumina furnace core tube 30 ...... thermocouple

Claims (2)

[Claims] 1. Calcium chloride having high purity with respect to oxygen,
Flux consisting of one or a mixture of two or more of barium chloride, magnesium chloride and calcium fluoride is heated and held in vacuum exhaust to sufficiently remove impurities such as water and carbon dioxide gas, and then put into a container together with titanium raw material. The first step of putting, and the second step of heating this in the temperature range of 750 ℃ ~ 1200 ℃, to cause the oxygen in titanium to deoxidize by causing calcium to act on titanium in a gas liquid state, and from the deoxidized titanium , A flux containing one or a mixture of two or more of calcium chloride containing by-produced CaO, barium chloride, magnesium chloride, calcium fluoride, a mineral acid, an organic acid, an ammonium chloride aqueous solution, an ammonium salt aqueous solution, and a sucrose aqueous solution. It consists of a third step in which only pure titanium that has been deoxidized is taken out by dissolution and removal by any one or more selected from Method for producing extremely low oxygen titanium, wherein the door. 2. The method for producing ultra-low oxygen titanium according to claim 1, wherein the flux is a mixture containing yttrium oxide.