WO2003106082A1

WO2003106082A1 - Method for producing metal powder and formed product of raw material for metal

Info

Publication number: WO2003106082A1
Application number: PCT/JP2003/007481
Authority: WO
Inventors: 岡部　徹; 今葷倍　正名
Original assignee: 財団法人生産技術研究奨励会; コンパニアブラジレイラヂメタルジアイミネラサウン
Priority date: 2002-06-13
Filing date: 2003-06-12
Publication date: 2003-12-24
Also published as: CN1658991A; AU2003252463A1; EP1512475A1; EP1512475A4; AU2003252463A8; CN1311943C; EP1512475B1; BR0311690A; US20060107788A1; DE60329388D1

Abstract

A method for producing a metal powder wherein a compound of the metal is used as a raw material and the compound is reduced, characterized in that it comprises a forming process of mixing the metal compound with a binding agent, forming the resultant mixture into a predetermined shape, and then firing, to prepare a formed product of the raw material for the metal, and a reducing process of contacting the formed product with an active metal, to thereby reduce the metal compound and form the metal. The method allows the direct production of a high pure metal powder from a compound of the metal with good efficiency, preferably with a continuous process and with ease.

Description

Description Metal powder production method and metal raw material molded body

The present invention relates to a method for producing a metal powder, and a metal raw material compact applicable to the method for producing the metal powder. Background art

High melting point rare metals, such as niobium and tantalum, not only have high melting points, but are also chemically active at high temperatures, so advanced technology is required to turn massive metals into powders. As one of the effective methods for producing such rare metal powders, the atomization method of powdering by spraying a liquid of a metal obtained by dissolving a metal is one of the effective powder production methods. Expensive equipment is required to dissolve the iron.

There is also the HDH method (hydrogenation, pulverization, dehydrogenation method), in which a rare metal is reacted with hydrogen to form a hydride and then mechanically pulverize it. Difficult to manufacture.

At present, high-melting point metals such as tantalum are industrially manufactured in powder form as a material for capacitors, but this powder is mainly used as a metal whose raw material is reduced by using an active metal as a reducing agent. It is manufactured by the thermal reduction method. Use of the metal thermal reduction method has the advantage that powdered tantalum can be directly produced by a reduction reaction. However, it is difficult to efficiently produce a large amount of uniform powder by the reduction reaction, and there is a drawback that the uniformity of the obtained powder is reduced particularly when the reaction amount is increased. At present, a large amount of halide-based molten salt is used as a reaction medium (diluting salt), and by adding a small amount of a raw material to the reaction medium little by little, a uniform reduction reaction proceeds to form a powder. Manufactures tantalum. Although this method is suitable for producing a high-purity and uniform powder, it has disadvantages such as requiring a large amount of reaction medium salt, and difficulty in increasing the size and speed of the process. Even if niobium is reduced by a method using a large amount of reaction medium salt according to the above-mentioned method, a uniform powder can be obtained. It is difficult to obtain a suitable powder. Disclosure of the invention

The present invention provides a method for producing a metal by reducing a metal compound using a metal compound as a raw material, wherein the metal compound is mixed with a binder, molded, and then fired to form a metal raw material molded body. A method for producing a metal powder, comprising: a forming step of producing; and a reducing step of reducing the metal raw material molded body to generate a metal by bringing the metal raw material molded body into contact with an active metal as a reducing agent. I do.

As the metal compound, a niobium compound can be used. Alternatively, a tantalum compound can be used as the metal compound. Alternatively, as the metal compound, a compound of a metal element selected from zirconium, titanium, hafnium, a rare earth metal, and an actinide metal can be used.

In the forming step, a metal compound, a binder, and an active metal compound as a reduction aid can be mixed to form a metal raw material molded body.

As the reducing agent, it is preferable to use at least one active metal selected from calcium, magnesium, sodium, potassium, and potassium.

As the reduction aid, it is preferable to use a compound of at least one active metal selected from calcium, magnesium, sodium, potassium, and potassium. It is preferable to use niobium oxide or halogenated niobium as the niobium compound.

It is preferable that the temperature of the compact in the reduction step is set to 600 ° C. or more and 130 ° C. or less.

In the forming step, it is preferable to form the metal raw material molded body into a shape in which a distance from an arbitrary position inside the metal raw material molded body to the surface of the molded body is 10 mm or less. The method for producing a metal powder preferably further includes a step of separating the metal generated in the reduction step from the active metal and by-products by an acid treatment.

Further, the present invention provides a metal raw material obtained by mixing a metal compound and a binder, molding and firing the mixture. A molded article, wherein a distance from an arbitrary position inside the molded article to the surface of the molded article is:

Provide a metal raw material compact having a size of 1 O mm or less.

It is preferable that the metal compound includes a compound raw material of a metal element selected from niobium, zirconium, titanium, hafnium, tantalum, a rare earth metal, and an actinide metal.

The metal raw material molded body may contain a compound of at least one metal selected from calcium, magnesium, sodium, barium, and magnesium as a reduction aid. The reduction aid is preferably an oxide, halide, or carbonate of at least one metal selected from calcium, magnesium, sodium, barium, and potassium. BRIEF DESCRIPTION OF THE FIGURES

-FIG. 1 is a cross-sectional configuration diagram showing a metal manufacturing apparatus according to the present invention.

FIG. 2 is a diagram showing an electron micrograph of the niobium powder produced in Example 1.

FIG. 3 is a view showing electron micrographs of the tantalum powders produced in Experimental Examples A to E of Example 2.

FIG. 4 is a diagram showing electron micrographs of the tantalum powder produced in Experimental Examples F to K of Example 2.

5A and 5B are graphs showing the particle size distribution of the tantalum powder produced in Example 2. FIG.

'' Best mode for carrying out the invention

The method for producing a metal powder according to the present invention is a method for producing a metal by reducing a metal compound using a metal compound as a raw material, mixing the metal compound with a binder, molding, and firing. And forming a metal raw material molded body by contacting the metal raw material molded body with an active metal as a reducing agent, thereby reducing the metal raw material molded body to generate a metal. It is characterized by. As the metal compound, niobium compound, tantalum compound, zirconium compound, titanium compound, Hafnium compounds, rare earth metal compounds or actinide metal compounds can be used.

Hereinafter, as an example of the method for producing a metal powder according to the present invention, a method for producing a niobium powder using a niobium compound will be specifically described.

The method for producing a niobium powder according to the present invention is a method for producing a niobium by using a niobium compound as a raw material and reducing the niobium compound, wherein the niobium compound is mixed with a binder to produce a slurry. Forming a niobium raw material molded body by forming it into a predetermined shape such as a plate, a line, or a granule, and baking the niobium raw material molded body, and bringing the active metal as a reducing agent into contact with the niobium raw material molded body Reducing the niobium compound to form niobium. As the niobium compound, niobium oxide or niobium halide can be used.

As the active metal, it is preferable to use one or more metals selected from calcium, magnesium, sodium, barium, and potassium. By reducing the niobium raw material compact using such an active metal, the reduction reaction can proceed efficiently. Furthermore, the use of magnesium as the active metal allows the reduction reaction to proceed most efficiently, and is particularly preferred.

It is preferable that the temperature of the molded body in the reduction step is 600 ° C. or more and 130 ° C. or less. If the temperature of the compact is lower than 600 ° C, the reducing agent has a low vapor pressure, and the reduction reaction tends not to proceed sufficiently.If the temperature of the compact exceeds 130 ° C, it is generated. Sintering of the niobium powder tends to proceed.

In the reduction step, it is preferable that the active metal is brought into contact with the niobium raw material molded body in a vaporized state. In this case, it is preferable to arrange the niobium raw material molded body in the reduction device so that air permeability is maintained, and to perform a reduction reaction. For example, in a reduction device having a support member and a heating device for supporting a plurality of niobium raw material compacts in a vertical position, a niobium raw material compact is disposed in a vertical position using the support members, and an active metal is reduced in the reduction device. Is placed on the bottom or on the support member or between adjacent niobium raw material compacts, and by heating the reducing device with a heating device, the active metal is degassed and brought into contact with the niobium raw material compact to reduce the active metal. The reaction can be performed. In this way, the niobium raw material compact is arranged in the reduction device so that air permeability is maintained. As a result, the vaporized active metal is diffused uniformly, so that the niobium raw material compact and the active metal can be brought into more uniform contact, and the reduction reaction progresses more uniformly in time and space, thereby reducing the reduction efficiency. Can be increased. In addition, since the niobium raw material compact does not come into direct contact with the reducing device, contamination from the reducing device can be prevented, and the purity of the obtained wipe powder can be increased.

Further, in the molding step of producing the niobium raw material molded body, an niobium raw material molded body can be produced by further mixing an active metal compound as a reduction aid in addition to the niobium compound and the binder. The active metal compound as the reduction aid can be used also as a binder, but can also be used to control the deposition form of niobium powder and increase the acid treatment efficiency. As described above, the reaction in the reduction step is more uniformly promoted by preparing the niobium raw material compact by mixing the niobium compound and the binder together with the active metal compound as a reduction aid, thereby increasing the production efficiency. Can be increased. Further, the particle size of the niobium powder to be produced can be controlled by adjusting the type of the reduction aid and the amount of the reduction aid. In addition, contamination from the reaction vessel can be effectively prevented.

As the reduction aid, it is preferable to use a compound of one or more metals selected from calcium, magnesium, sodium, potassium, and potassium, and oxides, halides, carbonates, and the like of these metals. More preferably, hydroxides, chlorides and / or fluorides are used. By using a molded article containing such an active metal compound as a reduction aid, the reaction efficiency and uniformity of the reduction step can be further improved.

Further, in the forming step, the shape of the niobium raw material formed body is preferably formed such that the distance from an arbitrary position inside the formed body to the surface of the formed body is 10 mm or less. The “distance from any position inside the molded body to the surface of the molded body” indicates the distance from any position inside the molded body to the shortest surface. In the reduction step in the manufacturing method, the reducing agent diffuses from the surface of the niobium raw material molded body into the inside, and the eob compound contained in the molded body is reduced. Therefore, if the shape of the compact is the above-mentioned shape, the maximum diffusion distance of the reducing agent from the surface of the compact at the end of the reduction reaction is 10 mm or less, and from the surface of the compact. The niobium raw material can be uniformly and rapidly reduced in the entire molded body without the diffusion treatment of the reducing agent diffused into the molded body being significantly different depending on the site.

Further, the method for producing niobium powder may further include a step of separating the niobium generated in the reduction step from a reducing agent, a reduction aid, and a by-product by an acid treatment. By providing a step of separation by acid treatment, niob, which is the target substance, and a reducing agent, a reduction auxiliary agent, and by-products generated by the reduction reaction can be easily separated, and high-purity niobium can be obtained. Can be manufactured in large quantities. Further, in the production method according to the present invention, since the niobium raw material compact is subjected to the reaction, the shape of the compact is substantially maintained even after reduction. Therefore, by performing an acid treatment on the molded body after the reduction, there is also an advantage that the reducing agent and the by-product can be efficiently removed.

The most important reason why a uniform powder cannot be obtained in the conventional rare metal manufacturing method is that if the amount of reduction is increased, the diffusion of the reducing agent into the raw material becomes non-uniform, and time and space This is probably because the progress of the reduction reaction becomes uneven. On the other hand, in the method for producing a uob powder according to the present invention, a niobium raw material, a binder (binder), and a no or reduction aid are mixed to form a niobium raw material molded body, and an active metal is brought into contact with the molded body. As a result, the reduction reaction is performed, so that even if the amount of reduction is increased, the reduction reaction can proceed uniformly in time and space. In addition, by setting the niobium raw material compact in the reduction device and allowing the reduction reaction to proceed, the reduction process can be continued, increased in size, and the efficiency of batch processing can be increased with a simple device. That is, in the conventional metal thermal reduction reaction, it has been difficult to make the process continuous and increase the speed. However, the compact of the niobium raw material used in the method for producing the niobium powder is manufactured, heat-treated, reduced, washed, etc. The process can be easily achieved, and the process can be easily made continuous and large. In addition, in the conventional method, when the amount of the raw material is increased, the particle size and the like of the obtained powder are often non-uniform, and the productivity is low. The reduction process can be easily increased in size and speed while maintaining uniformity of particle size, and productivity can be increased.

Next, a first embodiment of the present invention will be described in more detail with reference to the drawings. Figure 1 1 is a cross-sectional view illustrating an example of a metal manufacturing apparatus according to the present invention.

The production apparatus shown in FIG. 1 includes a reaction vessel 10 which is a closed vessel made of a heat-resistant material such as stainless steel, and a plurality of flat metal raw material molded bodies 12 arranged in the reaction vessel 10. Support members 13 and 14 are provided above and below the molded body 12 in order to support these molded bodies 12 in a vertical position. Then, the bottom of the reaction vessel 1 0, active metal 1 ⁵ has been introduced as a reducing agent for reducing the metal material compacts 1 2. Although a heating means is not shown in the illustrated reaction vessel 10, a heating means for heating the inside of the reaction vessel 10 to a predetermined temperature and evaporating the active metal 15 can be provided.

Then, the active metal 15 is heated and vaporized by the heating means to diffuse the gas of the active metal 15 into the reaction vessel 10, and the active metal 15 as a reducing agent is diffused from the surface of the molded body 12 to the inside. As a result, the metal compound contained in the molded body 12 is reduced to generate a metal.

In the method for producing niobium powder according to the present invention, niobium powder can be produced by a metal thermal reduction method using the above-described production apparatus. In order to produce the wool powder, first, in a molding step, a web raw material molded body containing a niobium compound as a raw material is produced. The molded body is preferably formed by mixing a niobium raw material, a binder (binder), and a reduction aid into a predetermined shape, and then preferably formed at a temperature of 300 to 100 ° C., more preferably 800 ° C. It is obtained by baking at a temperature of about 100 ° C. to remove the binder. If the calcination temperature is lower than 300 ° C., the binder and the reduction aid cannot be sufficiently removed, the reaction efficiency in the subsequent reduction step decreases, and the purity of the obtained powder tends to decrease. If the temperature exceeds 100 ° C., the sintering proceeds rapidly, and the niobium raw material molded body tends to change greatly. The firing step depends on the dimensions of the molded body, the heating temperature and the like, but is preferably performed for 1 to 12 hours, more preferably for about 1 to 6 hours, and even more preferably for about 3 to 6 hours. When firing is performed, it is preferable to perform firing in the atmosphere or in an oxygen atmosphere.

The niobium raw material, for _{_{example, N b 2 O s, N}} b OX ( a lower oxides of niobium, X is from 0.5 to 2. A is preferably _5), N b C l 5 or K, niobium compounds such as ₂ N b F ₇ can be used. In the niobium raw material compact, PC Mongolian 81

The amount of kicking the niobium raw material, 1 0 wt ^_0/0 or more, and more preferably 5 0 mass% or more. If the amount of the niobium raw material is 10% by mass or more, the reduction reaction is sufficiently performed, but the amount of the niobium raw material is 50% by mass. If it is less than / ₀ , the amount of acid used when separating niobium powder by acid treatment tends to increase, and the leaching efficiency tends to decrease.

Any binder can be used without any problem as long as it is irrelevant to the reduction reaction and can be easily removed by heat treatment. For example, an organic compound such as collodion or cellulose can be used. Further, a reducing aid can be used as a binder, and a molded article can be formed by mixing with a niobium raw material and a reducing aid. The amount of the binder in the above-mentioned raw material molded body is 5 to 80% by mass, more preferably 30 to 70% by mass, and still more preferably 30 to 50% by mass. / ₀ is preferred. If the amount of the binder is less than 5% by mass or more than 80% by mass, the strength of the molded article tends to decrease, and the formation of the molded article tends to be difficult.

The reduction aid is added to the niobium raw material and the binder as needed to form a molded body together with these. By dispersing the reduction aid in the compact, the reaction efficiency in the reduction step can be increased, and the reduction of the niobium raw material can be performed more uniformly. As the reduction aid, it is preferable to use a compound of at least one metal selected from the group consisting of calcium, magnesium, sodium, barium, and potassium, and oxides, halides, and carbonates of these metals are used. More preferably, salts, hydroxides, chlorides and / or fluorides are used. Specifically, calcium chloride, calcium carbonate, sodium carbonate, sodium chloride, or the like can be used alone or as a mixture. The compounding amount of the reducing aid is such that the cation in the reducing aid is 0 to 2 mol, more preferably 0.5 to 1 mol, based on 1 mol of niobium contained in the molded article. Is preferred. When the cation in the reduction aid exceeds 2 moles per 1 mole of niobium contained in the compact, the amount of acid used for acid washing increases when separating the generated hops by the acid treatment. And the leaching efficiency tends to decrease.

In addition, the shape of the molded body produced in the molding step includes: It is preferable that the shortest distance from an arbitrary position to the surface of the molded body is 10 mm or less, more preferably 2 to 5 mm. By adopting such a shape, the diffusion distance of the reducing agent diffused from the surface of the molded body toward the inside in the reduction step described later can be made 1 Omm or less, so that the reduction reaction can be performed quickly and uniformly. You can proceed. More specifically, for example, a shape such as a plate, a line, and a granule can be mentioned. In the case of a plate, in order to meet the above conditions, the plate thickness may be set to 20 mm or less. In this case, the distance between the outer periphery and the center in a cross section orthogonal to the center line in the length direction may be set to 1 Omm or less. Further, in the case of a granular shape, the diameter may be set to 2 O mm or less.

Next, the molded body obtained by the molding step is introduced as a molded body 12 into a reaction vessel 10 as shown in FIG. Although FIG. 1 illustrates a case where the molded body 12 is formed in a plate shape or a linear shape and these are supported in a vertical position, the arrangement state of the molded body 12 in the container is not limited to the illustrated arrangement. It can be appropriately changed according to the shape of the molded body.

An active metal 15 as a reducing agent is introduced into the bottom of the reaction vessel 10. As the active metal 15, it is preferable to use one or more metals selected from the group consisting of calcium, magnesium, sodium, barium, and magnesium. In the illustrated manufacturing apparatus, the active metal 15 is disposed at the bottom of the container. However, the active metal 15 may be disposed, for example, on a support member 14, and the molded bodies 12, 1 supported in a vertical position It may be arranged between two. The active metal 15 is, in the reaction vessel 10, 100 to 100 parts by mass of the molded body 12, 50 to 400 parts by mass, more preferably 100 to 30 ° parts by mass. It is preferable to introduce. When the active metal 15 is used in less than 50 parts by mass, the reduction reaction tends not to be sufficiently performed, and when it is used in excess of 400 parts by mass, the reduction efficiency tends not to be improved.

Next, the reaction vessel 10 is sealed, and the preparation for the reduction step is completed.

Then, the molded body 12 and the active metal 15 are introduced into the reaction vessel 10, and the reaction vessel 10 is placed in a heating furnace and heated. Then, the active metal 15 is vaporized by heating and is filled in the container 10, and at the same time, comes into contact with the molded body 12, and the reduction reaction proceeds from the surface of the molded body 12, and is contained in the molded body 12. Niobium raw material is reduced to niobium metal Is generated.

In the reduction step, it is preferable to heat the molded body 12 so that the temperature of the molded body 12 becomes 600 ° C. to 130 ° C. (more preferably, 800 ° C. to 100 ° C.). When the temperature is lower than 600 ° C, the vapor pressure of the active metal 15 as a reducing agent is low, and the reduction reaction does not tend to proceed sufficiently. When the temperature exceeds 130 ° C, niobium powder generated The reaction time depends on the dimensions of the molded body 12, the heating temperature, etc., but is about 1 to 6 hours, more specifically, the thickness of the molded body 12 is large. In the case of a plate having a thickness of several mm and heating at a temperature of 800 ° C. or more, the reduction reaction is completed sufficiently if the temperature is maintained for 1 hour or more.

Next, after the reaction vessel 10 is cooled, the compact after the reduction reaction is taken out of the vessel 10. The molded body after the reaction is composed of niobium, which is a force that substantially retains the shape of the molded body 12 before the reaction, a compound (by-product) of an active metal generated by the reduction, an excess reducing agent, and It is roughly composed of a reduction aid. Next, by subjecting the removed molded body to an acid treatment, it is possible to separate the generated niobium from the active metal compound, the reducing agent, the reduction aid, and the reaction product generated by the reduction, and the niobium powder Can be obtained. As the acid treatment, for example, after acid cleaning, an acid substitution treatment with water or an organic solvent is performed. Various acids such as hydrochloric acid, acetic acid, nitric acid, hydrofluoric acid, and sulfuric acid can be used for the acid cleaning.

In the production method according to the present invention, after the reduction reaction is completed, a molded body having substantially the same shape as the charged molded body 12 and containing the generated niobium can be obtained, and therefore, in the subsequent separation step As for the acid treatment, the permeability of the acid is good, and the niobium powder can be separated quickly and uniformly.

As described above, the raw material molded article according to the present invention has a feature that a flow operation such as a heat treatment (molding) step, a reduction step, and an acid treatment step in the production process can be easily achieved. In the case of processing, it is possible to easily cope with the problem by increasing the size and quantity of the molded body, and even if the processing quantity of the molded body is increased, the reaction speed and the uniformity of the reaction are not impaired. Therefore, according to the production method and the raw material compact according to the present invention, the process can be easily made continuous and the size can be increased. Further, according to the method for producing a niobium powder according to the present invention, a molded article containing a niobium raw material Since the raw material can be reduced at a high speed and uniformly by performing the reduction reaction through, the niobium powder obtained is also effective in that it has high purity and uniform particle size. ,

In the above embodiment, the method for producing niobium powder has been described in detail, but the production method according to the present invention can be similarly applied to the production of other metal powders. In other words, a target metal compound is used as a raw material, and in a molding step, this is mixed with a binder, molded into a predetermined shape, and then fired to form a metal raw material molded body. The target metal powder can be produced by reducing the metal raw material compact with an active metal in the reduction step, and preferably separating the active metal and by-products by an acid treatment. As the compound of the metal, a compound containing a metal element such as zirconium, titanium, platinum, tantalum, a rare earth metal, or an actinide metal is preferably used.

Next, the method for producing tantalum powder according to the present invention will be further described. The method for producing tantalum powder is a method for producing tantalum by using a tantalum compound as a raw material, reducing the tantalum compound, and mixing the tantalum compound with a binder to form a slurry. After forming into a predetermined shape such as a plate, a line, or a granule, and sintering to form a tantalum raw material molded body, the active metal as a reducing agent is brought into contact with the tantalum raw material molded body. A reduction step of reducing the tantalum compound to produce tantalum. As the tantalum compound, tantalum oxide or tantalum halide can be used.

The firing temperature in the forming step is preferably about 300 to 100 ° C., more preferably about 800 to 100 ° C., and the firing time is, for example, the size of the molded body and the heating temperature. It is preferably about 0.5 to 12 hours, more preferably about 1 to 6 hours, and still more preferably about 1 to 3 hours. If the firing temperature is less than 300 ° C., the binder cannot be sufficiently removed from the molded body, the reaction efficiency in the subsequent reduction step is reduced, and the purity of the obtained powder tends to decrease, If the temperature exceeds 100 ° C., the tantalum raw material molded body tends to be deformed. When firing is performed, it is preferable to perform firing in the air or in an oxygen atmosphere.

As the active metal, calcium, magnesium, sodium, barium, and It is preferable to use at least one metal selected from metals and potassium. By performing reduction of the tantalum raw material compact using such an active metal, the reduction reaction can proceed efficiently. Further, it is particularly preferable to use magnesium as the active metal because the reduction reaction can proceed most efficiently.

The temperature of the compact in the reduction step is preferably from 600 to 130 ° C, more preferably from 800 to 100 ° C. If the temperature of the compact is less than 600 ° C, the reducing agent tends to have a low vapor pressure, and the reduction reaction does not proceed sufficiently.If the temperature of the compact exceeds 130 ° C, the tantalum formed Sintering of the powder tends to proceed. Further, the reaction time in the reduction step is a force S depending on the dimensions and heating temperature of the tantalum raw material molded article, about 1 to 24 hours, preferably about 1 to 6 hours, and more preferably 3 to 6 hours. It is about.

In the reduction step, it is preferable that the active metal is brought into contact with the tantalum raw material molded body in a vaporized state. In this case, it is preferable to arrange the tantalum raw material molded body in the reduction device so that air permeability is maintained, and to perform the reduction reaction. For example, in a reduction device having a support member and a heating device for supporting a plurality of tantalum raw material compacts in a vertical position, the tantalum raw material compacts are arranged in a vertical position using the support members to reduce active metal. The active metal is vaporized by being placed at the bottom of the device, on the support member, or between adjacent tantalum raw material compacts, and heating the reducing device with a heating device, and brought into contact with the tantalum raw material compacts. A reduction reaction can be performed. In this way, by arranging the tantalum raw material compact in the reduction device so that air permeability is maintained, the vaporized active metal diffuses uniformly, so that the tantalum raw material compact and the active metal can be more uniformly dispersed. Contact can be made, and the reduction reaction proceeds more uniformly in time and space, and the reduction efficiency can be increased. In addition, since the tantalum raw material compact does not directly contact the reduction device, contamination from the reduction device can be prevented, and the purity of the obtained tantalum powder can be increased.

Further, in the forming step of preparing the tantalum raw material molded body, an active metal compound as a reduction aid may be further mixed in addition to the tantalum compound and the binder to form the tantalum raw material molded body. The active metal compound as the reduction aid can be used also as a binder, but controls the precipitation form of the tantalum powder, 7481

13 Can be used to increase acid treatment efficiency. As described above, by forming the tantalum raw material molded body by mixing the tantalum compound and the binder with the active metal compound as a reduction aid, the reaction in the reduction step is more uniformly promoted, Manufacturing efficiency can be increased. Further, the particle size of the generated tantalum powder can be controlled by adjusting the type of the reduction aid and the amount of the reduction aid mixed. Further, contamination from the reaction vessel can be effectively prevented.

As the reduction aid, it is preferable to use a compound of at least one metal selected from calcium, magnesium, sodium, potassium, and magnesium, and oxides, halides, and carbonates of these metals , Hydroxides, chlorides, and / or fluorides are more preferably used.Specifically, calcium chloride, calcium carbonate, sodium carbonate, sodium chloride, or the like is used alone or in combination. Can be used. The compounding amount of the reduction aid is such that the cation in the reduction aid is 0 to 2 mol, more preferably 0.5 to 1 mol, relative to 1 mol of tantalum contained in the molded article. It is preferable to mix them. By using a molded article containing such an active metal compound as a reduction aid, the reaction efficiency and uniformity of the reduction step can be further improved.

Further, in the forming step, it is preferable that the shape of the tantalum raw material formed body is formed such that the distance from an arbitrary position inside the formed body to the surface of the formed body is 10 mm or less. . The “distance from any position inside the molded body to the surface of the molded body” indicates the distance from any position inside the molded body to the shortest surface. In the reduction step in the manufacturing method, the reducing agent diffuses from the surface of the tantalum raw material molded body to the inside, and the tantalum compound contained in the molded body is reduced. Therefore, if the shape of the compact is the above-mentioned shape, the maximum diffusion distance of the reducing agent from the surface of the compact at the end of the reduction reaction is 10 mm or less, and the maximum diffusion distance from the surface of the compact to the inside of the compact is The diffusion treatment of the reducing agent to be performed does not significantly differ depending on the part, and the tantalum raw material can be uniformly and rapidly reduced in the entire molded body.

Further, the method for producing a tantalum powder further includes a step of separating the tantalum generated in the reduction step, a reducing agent, a reduction aid, and a by-product by an acid treatment. be able to. By providing a step of separation by acid treatment, the target substance, tantalum, and the reducing agent, reduction aid, and by-products generated by the reduction reaction can be easily separated, and high-purity tantalum can be obtained. Can be manufactured in large quantities. Further, in the production method according to the present invention, since the tantalum raw material compact is subjected to the reaction, the shape of the compact is substantially maintained even after reduction. For this reason, by performing an acid treatment on the molded body after the reduction, there is also an advantage that the reducing agent and by-products can be efficiently removed. Example

Next, the present invention will be described in more detail by way of examples, but the following examples do not limit the present invention. Example 1

In this example, niobium was produced by a metal thermal reduction reaction using the production apparatus shown in FIG.

To niobium raw material (Nb ₂ 〇 _5, 100 g), select one or more of the assistant reducing agent _{(C a C l 2, C} a CO 3, Na 2 C_〇 _3, N a C 1 Was added in an amount of 0 to 80% by weight. Specifically, the cations (C a ^{2 +} , N a ⁺ ) of the auxiliaries were 0, 1Z10, 1/5, and 12 moles with respect to Nbl moles.

Next, a slurry was prepared by mixing the niobium raw material, the reducing aid, and the binder. The binder was a 5% collodion solution (5% nitrocellulose, 40% ether, 55% ethanol) in the same volume as the raw material and auxiliary.

Then, an appropriate amount of acetone for adjusting the viscosity was added to the obtained slurry, and the mixture was poured into a 20 mm square mold having a thickness of several mm to produce a plurality of compacts. Two types of compacts were prepared, about 3 mm thick and about 6 mm thick.

Next, the obtained molded body was fired in a furnace in an air atmosphere at 1000 ° C. for 1 hour to completely remove the binder and the solvent water from the mixture of the niobium raw material and the auxiliary. By performing such calcination, reducing agent is saved and carbon contamination in the generated niobium powder is reduced. Can be prevented.

A plurality of the molded bodies obtained in this manner were devised so that air permeability was ensured, and they were put into a reaction vessel 10 together with a magnesium reducing agent (active metal 15), and the reaction vessel 10 was tightly closed. Next, the reaction vessel 10 into which the molded body 12 and the reducing agent 15 are introduced is put into an electric furnace maintained at 100 ° C. for 6 hours, and the reduction reaction is sufficiently advanced. Removed and cooled.

The compact (mixture of niobium metal powder, auxiliary and MgO, Mg) obtained after reduction is roughly washed with an aqueous acetic acid solution (1 + 1) and then twice with an aqueous IN HC1 solution. After replacing with water, alcohol, and acetone, it was dried.

Evaluation of the obtained niobium: Fig. 2 shows that the raw material compact of 50 x 20 x 3 mm square was reacted with magnesium vapor at 1000 ° C for 6 hours to reduce the niobium raw material. After cooling, the acetic acid aqueous solution (1+ After rough washing in 1), wash twice with 1N HC1 aqueous solution, replace with water, alcohol, and acetone, and then dry. It is a figure showing a photograph. Incidentally, the diagram showing the photograph shown in FIG. 2 is arranged in a matrix according to the type of auxiliary agent (horizontal axis) and the cation ratio (vertical axis).

As shown in this figure, it was found that the particle size of the niobium powder could be controlled by changing the type and amount of the auxiliary agent in the raw material compact. The width of one frame shown in the photograph is about 15 μm, and the particle size varies depending on the type and amount of the auxiliaries, but niobium powder having a primary particle size of about 0.5 to 3 m is obtained. Was done. Example 2

Also in this example, tantalum was produced by a metal thermal reduction reaction using the production apparatus shown in FIG.

In the composition described in Table 1, tantalum raw material (T a ₂ 0 _5), selecting one from among the assistant reducing agent _{(C a C 1 2, C} a C_〇 _{_{_{3, Na 2 C0 3, N}}} a C 1 ) And a binder were mixed to prepare a slurry. The binder was a 5% collodion solution (5% trocellulose, 40% ether, 55% ethanol) in the same volume as the tantalum raw material and the reducing aid. The viscosity of the slurry depends on the amount of reducing aid and binder added. Was adjusted by changing

Then, the obtained slurry was poured into a mold to produce a plate-like molded body having a thickness of 5 to 1 Omm.

Next, the obtained compact was fired in a furnace in an air atmosphere at 1000 ° C. for 3 hours to completely remove the binder, the solvent, and the water from the mixture of the tantalum raw material and the auxiliary agent. By performing such calcination, a reducing agent can be saved and carbon contamination in the generated tantalum powder can be prevented.

The resulting 4 to 10 compacts were placed in a reaction vessel 10 together with 20 g of a magnesium reducing agent (active metal 15) while maintaining the air permeability, and were welded with tungsten inert gas. The reaction vessel 10 was sealed. Next, the reaction vessel 10 into which the molded body 12 and the reducing agent 15 are introduced is put into an electric furnace maintained at 700 to 1000 ° C. for 6 to 24 hours, and the reduction reaction is sufficiently advanced. Removed from the furnace and cooled.

After the reduction, the compact (mixture of metal tantalum powder, auxiliaries, and Mg and Mg) is roughly washed with an aqueous acetic acid solution (1 + 1), and then washed twice with an aqueous 1N HC1 solution. Further, after substitution with water, alcohol, and acetone, the mixture was dried.

In Table 1, X represents the number of moles of cation contained in the reduction aid per 1 mole of tantalum.

The morphology of the obtained tantalum powder was observed using a scanning electron microscope, and the particle size distribution was examined by optical diffraction analysis.

FIGS. 3 and 4 are photographs showing the morphology of the tantalum powder obtained in Experimental Examples A to K by scanning electron microscopy. As shown in FIG. 3, the obtained tantalum powder had a coral-like morphology with a particle size of 0.1 to 0.5 μm. In the case of using a calcium compound as an assistant reducing agent, if with respect to the particle size of the tantalum powder obtained that Ru uniform der, with N a C 1 or N a C_〇 ₃ as a reducing aid, give The resulting tantalum powder contained two types of particles, a small particle having a particle size of 0.1 to 0.2 μιη and a large particle having a particle size of about 0.5 m. As shown in Fig. 4, the tantalum powder obtained by increasing the amount of the Increased in particle size.

FIG. 5A is a graph showing the particle size distribution of the tantalum powder obtained in Experiments B, D, and O. This indicates that a powder having a smaller particle size tends to be obtained when a sodium compound is used as a reduction aid than when a calcium compound is used. In addition, it was shown that when a calcium compound was used as a reduction aid, the particle size of the obtained tantalum powder became more uniform.

FIG. 5B is a graph showing the particle size distribution of the tantalum powder obtained in Experiments H, I, and O. As a result, it was shown that the particle size of the obtained tantalum powder was increased by increasing the amount of the reducing aid in the molded body.

From these results, it was shown that the particle size of the tantalum powder can be controlled by changing the type and amount of the reduction aid in the raw material compact. Industrial applicability

As described above in detail, according to the method for producing niobium powder according to the present invention, the reduction reaction can proceed uniformly, and the reduction reaction can be performed by installing the molded body of the niobium raw material in the reduction device. By proceeding, the reduction process can be continued, increased in size, and the efficiency of batch treatment can be performed with a simple device, and high-purity niobium powder can be efficiently produced directly from the niobium compound.

Further, according to the method for producing a tantalum powder according to the present invention, the reduction reaction can proceed uniformly, and the reduction process can be performed by installing a compact of the tantalum raw material in the reduction device and performing the reduction reaction. Continuity, upsizing, and batch processing efficiency can be performed with simple equipment, and high-purity tantalum powder can be efficiently produced directly from tantalum compounds.

Further, according to the method for producing a metal powder according to the present invention, a metal powder such as zirconium other than niobium and tantalum, titanium, hafnium, a rare earth metal, and an actinoid metal can be efficiently produced with high purity from a metal compound. Preferably, it can be manufactured continuously.

The metal raw material molded product according to the present invention is a metal compound molded product obtained by mixing a metal compound and a binder, forming the mixture into a predetermined shape, and firing the mixture. The distance from any part of the part to the surface of the compact is set to 1 Omm or less, so that the diffusion distance of the reducing agent from the surface of the compact is 10 mm or less. The metal compound can be uniformly and rapidly reduced.

Claims

The scope of the claims

1. A method for producing a metal by reducing a metal compound using a metal compound as a raw material,

A molding step of mixing the metal compound with a binder, molding, and then firing to produce a metal raw material molded body; and

A reducing step of reducing the metal raw material molded body to generate a metal by bringing the metal raw material molded body into contact with an active metal as a reducing agent;

A method for producing a metal powder comprising:

2. The method for producing a metal powder according to claim 1, wherein a niobium compound is used as the metal compound.

3. The method for producing a metal powder according to claim 1, wherein a tantalum compound is used as the metal compound.

4. The method for producing a metal powder according to claim 1, wherein the metal compound is a compound of a metal element selected from zirconium, titanium, hafnium, rare earth metal, and actinide metal.

5. The method for producing a metal powder according to claim 1, wherein in the forming step, a metal compound, a binder, and an active metal compound as a reduction aid are mixed to form a metal raw material molded body.

6. The method for producing a metal powder according to claim 1, wherein as the reducing agent, at least one active metal selected from calcium, magnesium, sodium, potassium, and potassium is used.

7. Calcium, magnesium, sodium, barium, 3. The method for producing a metal powder according to claim 2, wherein a compound of at least one active metal selected from the group consisting of an active metal and a steel is used.

8. The method for producing a metal powder according to claim 2, wherein niobium acid or niobium halide is used as the niobium compound.

9. The method for producing a metal powder according to claim 1, wherein the temperature of the compact in the reduction step is set to 600 ° C. or more and 130 ° C. or less.

10. The metal powder according to claim 1, wherein in the forming step, the metal raw material molded body is formed into a shape in which a distance from an arbitrary position inside the metal raw material molded body to the surface of the molded body is 1 O mm or less. Manufacturing method.

11. The method for producing a metal powder according to claim 1, further comprising a step of separating the metal generated in the reduction step from the active metal and by-products by an acid treatment.

1 2. A metal raw material molded body obtained by mixing a metal compound and a binder, molding and firing.

A metal raw material molded body in which a distance from an arbitrary position inside the molded body to a surface of the molded body is 10 mm or less.

13. The molded metal raw material according to claim 12, wherein the metal compound includes a compound raw material of a metal element selected from niobium, zirconium, titanium, hafium, tantalum, a rare earth metal, and an actinoid metal.

14. The metal according to claim 12, wherein the metal raw material compact contains, as a reduction aid, a compound of at least one metal selected from calcium, magnesium, sodium, rubber, and steel. Raw material compact.

15. The shaped metal raw material according to claim 14, wherein the reduction aid is an oxide, halide, or carbonate of at least one metal selected from calcium, magnesium, sodium, barium, and potassium. .