JP2981090B2 - Production method of high purity metal - Google Patents
Production method of high purity metalInfo
- Publication number
- JP2981090B2 JP2981090B2 JP5239610A JP23961093A JP2981090B2 JP 2981090 B2 JP2981090 B2 JP 2981090B2 JP 5239610 A JP5239610 A JP 5239610A JP 23961093 A JP23961093 A JP 23961093A JP 2981090 B2 JP2981090 B2 JP 2981090B2
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- hydrogen
- metal
- melting
- arc melting
- metal impurities
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、高融点金属もしくは貴
金属中に含まれる微量の金属不純物を除去することによ
って、高純度の高融点金属および貴金属を製造する方法
に関するものである。とくに本発明は、Na, Ｋなどアル
カリ金属不純物、Fe, Niなど鉄族の金属不純物および
Ｕ，Thなど放射性金属不純物を効果的に除去し、これら
の不純物を極低濃度レベルとした高純度の高融点金属お
よび貴金属の精製, 回収方法を提案する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-purity refractory metal or a noble metal by removing a trace amount of metal impurities contained in the refractory metal or a noble metal. In particular, the present invention effectively removes alkali metal impurities such as Na and K, iron group metal impurities such as Fe and Ni, and radioactive metal impurities such as U and Th, and removes these impurities to an extremely low concentration level. We propose a purification and recovery method for refractory metals and precious metals.
【０００２】[0002]
【発明の背景】高融点金属や貴金属は、電子材料や機能
性材料としての用途にも使われているが、実用化に当た
って重要なことは、素材の高純度化である。例えば、Ｌ
ＳＩの分野においてその応用が期待されているMoやＷ等
の高融点金属ターゲット材については、ＭＯＳデバイス
の特性を劣化させるNaなどアルカリ金属不純物や、Feな
ど鉄族の金属不純物の極低化が、また、アルファー線を
放出し誤作動の原因となるＵ，Th等の金属不純物の極低
化が、それぞれ強く求められている。こうした背景の下
で、近年、原料金属から高純度の高融点金属, 貴金属を
精製, 回収するための、操業が容易で経済的にも有利な
製造技術の確立が求められていた。BACKGROUND OF THE INVENTION High melting point metals and noble metals are also used as electronic materials and functional materials, but in practical use, it is important to purify the materials. For example, L
For refractory metal target materials such as Mo and W, which are expected to be applied in the field of SI, extremely low levels of alkali metal impurities such as Na, which degrade the characteristics of MOS devices, and iron group metal impurities such as Fe, are required. Further, there is a strong demand for extremely low levels of metallic impurities such as U and Th which emit alpha rays and cause malfunctions. Against this background, in recent years, it has been required to establish an easy-to-operate and economically advantageous manufacturing technique for purifying and recovering high-purity high-melting-point metals and precious metals from raw metal.
【０００３】[0003]
【従来の技術およびその解決課題】さて、高融点金属を
製造する精製方法としては、電子ビーム溶解が一般に用
いられている。この従来技術は、10-4〜10-6トルの高真
空中で電子ビーム衝撃により被溶解金属を加熱溶解する
方法であって、蒸気圧差を利用して金属不純物を除去し
て精製する方法、即ち、被溶解金属に比し蒸気圧が高い
金属不純物の蒸発除去によるその低減化技術である。た
だし、この技術の場合、排気量の大きな高真空排気装置
が必要であり、しかも高真空を長時間保持することが必
要なことから、装置が大掛かりとなる欠点があった。ま
た、金属不純物を極低濃度にまで低減させるには、真空
中での長時間溶解が不可欠であり、高融点金属自体の蒸
発損失が増加するために、歩留りが悪いという欠点もあ
った。2. Description of the Related Art Electron beam melting is generally used as a refining method for producing refractory metals. This prior art is a method of heating and melting a metal to be melted by electron beam bombardment in a high vacuum of 10 -4 to 10 -6 torr, a method of removing and purifying metal impurities using a vapor pressure difference, In other words, this is a technique for reducing metal impurities having a higher vapor pressure than the metal to be dissolved by evaporating and removing the impurities. However, in the case of this technique, a high-vacuum evacuation device having a large exhaust amount is required, and further, it is necessary to maintain a high vacuum for a long time, so that there is a drawback that the device becomes large-scale. Further, in order to reduce metal impurities to an extremely low concentration, long-time melting in a vacuum is indispensable, and the evaporation loss of the high-melting-point metal itself increases, so that the yield is poor.
【０００４】さらに、上記従来技術では放射性金属不純
物の除去が困難である。即ち、たとえ高真空溶解を行な
ったとしても、この高融点金属中のＵ，Thを極低濃度域
にまで減じることは不可能と言える。このことから従
来、MoやＷ中のＵ, Thの極低化には、イオン交換法やハ
ロゲン化法などが採用されている。例えば、「東芝レビ
ュー」第48巻 (1988年), 761頁では、原料Mo金属を酸で
溶解後、水溶液の状態でイオン交換精製し、濃縮・乾燥
してMo酸化物粉とし、その後、水素還元によって高純度
Mo粉を回収し、そして、最終段階で電子ビーム溶解を行
っている。また、特開平５−65509 号公報では、Ｗをオ
キシ塩化物とした後、Ｗオキシ塩化物の沸点が金属不純
物に比し大きいことを利用し、Ｗ成分のみを揮発させて
Ｕ, Thなどの放射性金属不純物と分離し、さらにその
後、高純度Ｗオキシ塩化物の加水分解によりＷ酸化物を
得たのち、水素還元してＷ金属粉末を得る方法を開示し
ている。しかし、この技術は、塊状のＷを得るには、さ
らに何らかの溶解法との併用が必要である。以上説明し
た各従来技術によれば、Ｕ, Thなどの放射性金属不純物
を１mass ppb以下にまで低減可能であるが、高純度Moお
よびＷを得るまでにはなお多段階の工程を必要とし、し
かもそのためには、各工程で汚染防止など厳密な工程管
理が不可欠であり、従って経済性の観点からは大いに問
題があった。[0004] Further, it is difficult to remove radioactive metal impurities by the above-mentioned prior art. That is, even if high-vacuum melting is performed, it can be said that it is impossible to reduce U and Th in this high melting point metal to an extremely low concentration range. For this reason, the ion exchange method, the halogenation method, and the like have been conventionally used to minimize U and Th in Mo and W. For example, in Toshiba Review, Vol. 48 (1988), p. 761, raw Mo metal is dissolved in an acid, ion-exchange purified in the form of an aqueous solution, concentrated and dried to form Mo oxide powder, and then hydrogen High purity by reduction
Mo powder is recovered, and electron beam melting is performed in the final stage. In Japanese Patent Application Laid-Open No. 5-65509, after W is converted to oxychloride, utilizing the fact that the boiling point of W oxychloride is higher than that of metal impurities, only the W component is volatilized to remove U, Th, etc. It discloses a method of separating a radioactive metal impurity, further obtaining a W oxide by hydrolyzing a high-purity W oxychloride, and then reducing the hydrogen to obtain a W metal powder. However, this technique needs to be used in combination with some other dissolving method in order to obtain massive W. According to each of the prior arts described above, radioactive metal impurities such as U and Th can be reduced to 1 mass ppb or less, but multi-step processes are still required to obtain high-purity Mo and W, and For that purpose, strict process control such as prevention of contamination in each process is indispensable, and thus there is a great problem from the viewpoint of economy.
【０００５】本発明の目的は、精錬装置およびその付帯
装置の大型化や操業の煩雑化を招くことなく、高純度の
高融点金属および貴金属を容易に精製・回収するための
技術を提供することにある。An object of the present invention is to provide a technique for easily purifying and recovering a high-purity high-melting-point metal and a noble metal without increasing the size of the refining apparatus and its accompanying equipment and complicating the operation. It is in.
【０００６】[0006]
【課題を解決するための手段】本発明者らは、上記各従
来技術が抱えている解決課題につき鋭意研究した結果、
水素プラズマアーク溶解法または水素雰囲気アーク溶解
法を適用することにより、高融点金属または貴金属等を
溶解処理することにより、単一溶解工程の処理で、高融
点金属等の中に含まれる微量のNaなどアルカリ金属不純
物、Fe, Niなど鉄族の金属不純物、更にＵ，Thなどの金
属不純物を迅速に蒸発除去することが可能であるという
知見を得て本発明を完成したものである。即ち本発明
は、３気圧程度の加圧下から10トル程度の減圧下での水
素プラズマアーク溶解または水素雰囲気溶解を行うこと
によって、5000℃以上のプラズマまたはアーク高温雰囲
気中で活性水素Ｈを解離生成させ、この活性水素Ｈの作
用効果を利用することにより、単一溶解工程の処理で、
実施例１〜４に記載されているように、純度が99mass％
以上の金属から99.999mass％以上の、さらに高純度の高
融点金属または貴金属を得るようにしたものである。Means for Solving the Problems The present inventors have made intensive studies on the problems to be solved by the above prior arts, and as a result,
By applying the hydrogen plasma arc melting method or the hydrogen atmosphere arc melting method to dissolve the high melting point metal or the noble metal, etc., in a single melting step, the trace amount of Na contained in the high melting point metal etc. The present invention has been completed based on the finding that alkali metal impurities, iron group metal impurities such as Fe and Ni, and metal impurities such as U and Th can be rapidly removed by evaporation. That is, the present invention dissolves and generates active hydrogen H in a plasma or arc high-temperature atmosphere of 5000 ° C. or more by performing hydrogen plasma arc melting or hydrogen atmosphere melting under a pressure of about 3 atm to a pressure of about 10 torr. And by utilizing the action and effect of the active hydrogen H, the treatment in a single dissolution step
As described in Examples 1-4, the purity was 99 mass%
A high-purity high-melting-point metal or a noble metal with a purity of 99.999 mass% or more is obtained from the above metals.
【０００７】このような考え方の下に開発された本発明
の要旨構成は次のとおりである。 (1) 純度が99％以上のIVa 族、Va族およびVIa 族に属す
る高融点金属もしくは貴金属を、水素含有高温雰囲気下
で活性水素Ｈを発生させてアーク溶解することにより、
金属不純物を蒸発除去することを特徴とする高純度金属
の製造方法。 (2) 活性水素Ｈを発生させるための手段としては、水素
プラズマアーク溶解法または水素雰囲気アーク溶解法を
用いる。 (3) 活性水素Ｈを発生させるために、溶解雰囲気の温度
を5000℃以上に保持して水素プラズマ溶解または水素雰
囲気アーク溶解を行うこと。 (4) 水素プラズマアーク溶解または水素アーク溶解の作
動ガスとして、２〜100％の水素を含むガスを使用する
こと。 (5) 水素プラズマアーク溶解および水素アーク溶解に当
たっては、炉内圧を３気圧〜10トルに調整すること。[0007] The gist configuration of the present invention developed under such a concept is as follows. (1) A high melting point metal or a noble metal belonging to Group IVa, Va and VIa having a purity of 99% or more is arc-melted by generating active hydrogen H in a hydrogen-containing high-temperature atmosphere.
A method for producing a high-purity metal, comprising removing metal impurities by evaporation. (2) As a means for generating active hydrogen H, a hydrogen plasma arc melting method or a hydrogen atmosphere arc melting method is used. (3) In order to generate active hydrogen H, the temperature of the melting atmosphere is maintained at 5000 ° C. or higher, and hydrogen plasma melting or hydrogen atmosphere arc melting is performed. (4) As the working gas for hydrogen plasma arc melting or hydrogen arc melting, use a gas containing 2 to 100% hydrogen. (5) For hydrogen plasma arc melting and hydrogen arc melting, adjust the furnace pressure to 3 atm to 10 torr.
【０００８】[0008]
【作用】ところで、高融点金属や貴金属を、３気圧〜10
トル程度の炉内圧の不活性ガス雰囲気（たとえばAr雰囲
気) 下で溶解処理する場合、金属不純物が高融点金属や
貴金属に較べて、より大きな蒸気圧を有するものであっ
たとしても、前述した高真空溶解の場合に較べると、該
金属不純物の除去低減化が非常に困難である。これに対
し、本発明者らの研究によると、溶解雰囲気内に水素を
導入しプラズマアーク溶解またはアーク溶解を実施した
場合には、上記と同じ条件での処理：即ち、３気圧〜10
トル程度での溶解処理であっても、高融点金属等に比べ
てより大きな蒸気圧を有するNaなどアルカリ金属不純
物、Fe, Niなど鉄族の金属不純物、またはＵ，Thなどの
金属不純物が、それぞれ迅速に蒸発除去され、高融点金
属や貴金属等を容易に高純度化できることが判った。[Effect] By the way, high melting point metal and noble metal are reduced to 3 atm.
When the dissolution treatment is performed in an inert gas atmosphere (for example, an Ar atmosphere) having a furnace pressure of about Torr, even if the metal impurities have a higher vapor pressure than the high melting point metal or the noble metal, the above-described high melting point can be obtained. Compared to the case of vacuum melting, it is very difficult to reduce and reduce the metal impurities. On the other hand, according to the study of the present inventors, when plasma arc melting or arc melting is performed by introducing hydrogen into the melting atmosphere, the treatment under the same conditions as above: namely, 3 atm.
Even in the melting process at about Torr, alkali metal impurities such as Na having a higher vapor pressure than high melting point metals, iron group metal impurities such as Fe and Ni, or metal impurities such as U and Th, It was found that each was quickly evaporated and removed, and that high melting point metals, noble metals, and the like could be easily purified.
【０００９】本発明にかかる前記処理の作用・効果は、
高融点金属または貴金属等を水素プラズマアーク溶解ま
たは水素雰囲気中アーク溶解して精製することにより実
現される。このような精製方法により高融点金属中の金
属不純物が効果的に除去される理由は、以下のような機
構により生じる。The operation and effect of the processing according to the present invention are as follows:
It is realized by purifying a high melting point metal or a noble metal by hydrogen plasma arc melting or arc melting in a hydrogen atmosphere. The reason why metal impurities in the refractory metal are effectively removed by such a purification method is caused by the following mechanism.
【００１０】一般に、水素は、5000℃以上の高温で、
(1) 式のように解離し活性水素Ｈとして存在する。 Ｈ2 →Ｈ＋Ｈ …(1) この活性水素Ｈは、通常の水素Ｈ2 に比べて反応性、還
元性が著しく優れており、それ故に、この活性水素Ｈを
利用すると優れた精製効果が得られるのである。すなわ
ち、金属不純物（蒸気）は一般に、水素プラズマ相と接
する溶融金属表面上のガス側境界層内において、下記
(2) 式に示すように、 xＭ［蒸気］＋ yＨ［活性水素］→Ｍx Ｈy ［一次的な
緩い結合］…(2) （Ｍ：溶融金属表面上の、Naなどアルカリ金属不純物、
Fe, Niなど鉄族の金属不純物、更にＵ，Thなど金属不純
物の蒸気） 反応し、高融点金属や貴金属よりも高い蒸気圧を有する
金属不純物の蒸気と活性水素Ｈとが一次的な緩い結合を
生じ、活性水素Ｈがこれら金属不純物蒸気を捕捉する形
でガス相側に搬出し、その結果、高い蒸気圧を有する金
属不純物の蒸発除去を促進するのである。このことによ
って、水素プラズマアーク溶解時の高融点金属浴または
貴金属浴からNaなどアルカリ金属不純物、Fe, Niなど鉄
族の金属不純物、更にＵ，Thなど金属不純物が迅速に蒸
発除去されることになる。さらに、この活性水素Ｈの存
在は、溶融金属表面の酸素の還元除去にも有効に作用
し、そのために金属不純物の蒸発が一層容易になる。こ
のことが、本発明において金属不純物の除去を一層促進
するのである。Generally, hydrogen is used at a high temperature of 5000 ° C. or more,
It dissociates and exists as active hydrogen H as shown in equation (1). H 2 → H + H (1) The active hydrogen H has remarkably excellent reactivity and reducibility as compared with normal hydrogen H 2 , and therefore, if this active hydrogen H is used, an excellent purification effect can be obtained. It is. That is, metal impurities (vapors) generally form the following in the gas-side boundary layer on the surface of the molten metal in contact with the hydrogen plasma phase:
As shown in the equation (2), xM [steam] + yH [active hydrogen] → Mx Hy [primary loose bond] (2) (M: alkali metal impurities such as Na on the molten metal surface,
Vapor of iron impurities such as iron and metal such as Fe and Ni, and vapor of metal impurities such as U and Th. Then, the active hydrogen H is carried out to the gas phase side in such a manner as to capture these metal impurity vapors, and as a result, the evaporation and removal of metal impurities having a high vapor pressure are promoted. As a result, alkali metal impurities such as Na, iron group metal impurities such as Fe and Ni, and metal impurities such as U and Th are rapidly evaporated and removed from the high melting point metal bath or the noble metal bath during melting of the hydrogen plasma arc. Become. Further, the presence of the active hydrogen H also effectively acts on the reduction and removal of oxygen on the surface of the molten metal, thereby making it easier to evaporate metal impurities. This further promotes the removal of metal impurities in the present invention.
【００１１】なお、前述した活性水素Ｈを発生させるた
めの溶解雰囲気の温度は、5000℃以上とすることが要求
されるが、この温度は水素分子の解離に必要な温度であ
り、この温度条件であれば、３気圧〜10トルの雰囲気の
下でも、有効な活性水素Ｈを得ることができる。The temperature of the dissolving atmosphere for generating the active hydrogen H is required to be 5000 ° C. or higher, which is a temperature required for dissociation of hydrogen molecules. Then, effective active hydrogen H can be obtained even under an atmosphere of 3 atm to 10 torr.
【００１２】したがって、本発明によれば、高融点金属
および貴金属を、高真空を用いることなく、３気圧〜10
トル程度の炉内圧でのプラズマアーク溶解法または水素
雰囲気中アーク溶解法に従う処理によって、Naなどアル
カリ金属不純物、Fe, Niなどの鉄族金属不純物、または
Ｕ，Thなどの金属不純物を、極低濃度域まで低減するこ
とができる。また、本発明は、３気圧〜10トル程度の炉
内圧を用いる溶解法であることから、目的金属である高
融点金属や貴金属の蒸発損失が極めて少なく、高融点金
属や貴金属を高い歩留りの下に回収することができる。Therefore, according to the present invention, the high melting point metal and the noble metal can be removed from 3 atm to 10 atm without using a high vacuum.
The process according to the plasma arc melting method at a furnace pressure of about Torr or the arc melting method in a hydrogen atmosphere reduces alkali metal impurities such as Na, iron group metal impurities such as Fe and Ni, or metal impurities such as U and Th to an extremely low level. It can be reduced to the concentration range. Further, since the present invention is a melting method using a furnace pressure of about 3 atm to about 10 torr, evaporation loss of the high melting point metal and the noble metal as the target metal is extremely small, and the high melting point metal and the noble metal can be removed at a high yield. Can be recovered.
【００１３】[0013]
【実施例】以下、本発明を実施例により具体的に説明す
る。 実施例１ Zr−１mass％Fe合金を、１気圧(101KPa)および減圧下
（70トル：9.3KPa) でH2(10, 20, 30, 40, 50vol ％)
−Arプラズマ溶解したときの、溶解時間に対するZr中の
Fe濃度変化を調べた。その結果を図１に示す。参考のた
めに、Arプラズマ（水素が存在しない状態）溶解の結果
も併せて示した。この図に明らかなとおり、１気圧でAr
プラズマのみで加熱溶解した場合、ZrからのFe蒸発によ
るFeの除去低減化は進まないが、プラズマガスに水素を
加えると、Feの蒸発が起こってZr中のFe濃度は迅速に除
去され低減する。また、プラズマガス中の水素濃度が10
vol％から50 vol％へと増加するのに従い、さらに１気
圧よりは70トルと、減圧にするほどFeの除去速度は向上
し、例えば70トル減圧下で50 vol％H2−Arプラズマ溶解
では、 180分溶解処理後には、Zr中のFe濃度は１mass p
pmにまで低減化が可能であった。しかも、 180分溶解後
のZrの蒸発損失は小さく、Zrの歩留りは約98％と良好で
あった。The present invention will be described below in more detail with reference to examples. Example 1 Zr-1 mass% Fe alloy, 1 atm (101 KPa) and reduced pressure (70 Torr: 9.3 kPa) at H 2 (10, 20, 30 , 40, 50vol%)
-Ar plasma melting, Zr in melting time to melting time
The change in Fe concentration was investigated. The result is shown in FIG. For reference, the results of Ar plasma (in the absence of hydrogen) dissolution are also shown. As is clear from this figure, Ar at 1 atm.
When heating and melting only with plasma, the reduction of Fe removal by evaporation of Fe from Zr does not progress, but when hydrogen is added to the plasma gas, the evaporation of Fe occurs and the Fe concentration in Zr is quickly removed and reduced . The hydrogen concentration in the plasma gas is 10
According to increase from vol% to 50 vol%, further 70 torr than one atmosphere, the removal rate of Fe as reducing the pressure is increased, for example, under 70 torr vacuum at 50 vol% H 2 -Ar plasma dissolution After the dissolution treatment for 180 minutes, the Fe concentration in Zr is 1 mass p
It was possible to reduce to pm. Further, the evaporation loss of Zr after melting for 180 minutes was small, and the yield of Zr was as good as about 98%.
【００１４】実施例２ 公称純度99.9％の比較的高純度の Ta 約30ｇを、１気圧
下で60分の30％H2−Arプラズマ溶解した時の、水素プラ
ズマ溶解前後のTa中の各微量金属不純物の濃度を、表１
に示す。微量金属不純物分析にはグロー放電質量分析法
を使用した。この表１に示すとおり、原料Ta中のNaは0.
01mass ppm前後と微量であるが、さらに水素プラズマ溶
解を経ることで、0.003 mass ppm (3 mass ppb) 程度に
まで減少した。同様にFe, Niなど鉄族の金属不純物も、
１〜14 mass ppm から0.01 mass ppm (10 mass ppb) 以
下に、またＵ，Thも0.001 mass ppm (1 mass ppb) 以下
の極微量にまで減ずることができた。すなわち、煩雑で
厳密な工程管理が必要となる多段階の工程を経ることな
く、単一の溶解工程により各金属不純物が極低濃度域ま
で低減させることが可能である。Example 2 When about 30 g of relatively high-purity Ta having a nominal purity of 99.9% was melted by 30% of 60% H 2 -Ar plasma at 1 atm for 30 minutes, each trace amount in Ta before and after hydrogen plasma melting was dissolved. Table 1 shows the concentration of metal impurities.
Shown in Glow discharge mass spectrometry was used for trace metal impurity analysis. As shown in Table 1, Na in the raw material Ta was 0.1%.
Although the amount was as small as about 01 mass ppm, it decreased to about 0.003 mass ppm (3 mass ppb) by further hydrogen plasma dissolution. Similarly, iron group metal impurities such as Fe and Ni
From 1 to 14 mass ppm, it was possible to reduce U and Th to an extremely small amount of 0.001 mass ppm (1 mass ppb) or less from 0.01 mass ppm (10 mass ppb) or less. That is, each metal impurity can be reduced to an extremely low concentration region by a single melting step without going through a multi-step process that requires complicated and strict process control.
【００１５】[0015]
【表１】 [Table 1]
【００１６】実施例３ 表２は、公称純度99.9％のMo約20ｇを、70トルの減圧下
で40％H2−Arプラズマ溶解した時の、水素プラズマ溶解
前後のMo中の各微量金属不純物の濃度を示すものであ
る。なお、微量金属不純物分析にはグロー放電質量分析
法を使用した。表２に示すように、水素プラズマアーク
溶解を施すことにより、Naは 0.2massppmから0.005 mas
s ppm (5 mass ppb) 程度にまで減少している。同様
に、Fe,Niなど鉄族の金属不純物は、５〜25 mass ppm
から0.01 mass ppm (10 mass ppb) 以下に、またＵ，Th
はともに 0.001 mass ppm (1 mass ppb)以下の極微量に
まで減ずることが判った。すなわち、単一の溶解工程に
より、Mo中の各金属不純物は極低濃度まで低減でき、高
純度Moを回収することが可能であることが確かめられ
た。Example 3 Table 2 shows that each trace metal impurity in Mo before and after dissolution of hydrogen plasma when about 20 g of Mo having a nominal purity of 99.9% was melted by 40% H 2 -Ar plasma under a reduced pressure of 70 torr. This shows the concentration of. Glow discharge mass spectrometry was used for trace metal impurity analysis. As shown in Table 2, by performing hydrogen plasma arc melting, Na was reduced from 0.2 mass ppm to 0.005 mas.
s ppm (5 mass ppb). Similarly, iron group metal impurities such as Fe and Ni are 5 to 25 mass ppm
To less than 0.01 mass ppm (10 mass ppb)
Was reduced to an extremely small amount of 0.001 mass ppm (1 mass ppb) or less. That is, it was confirmed that each metal impurity in Mo can be reduced to an extremely low concentration by a single melting step, and high-purity Mo can be recovered.
【００１７】[0017]
【表２】 [Table 2]
【００１８】実施例４ 小型アーク溶解炉にガス供給口およびガス排出口を設置
し、50％H2−Ar混合ガスをアーク溶解炉内に毎分５リッ
トルで供給しながら、公称純度 99.95％の比較的高純度
のPd、約25ｇの水素雰囲気中アーク溶解を行った。表３
は原料Pd中の金属不純物と溶解時間60分後のPd中各金属
不純物の濃度を示すものである。なお、金属不純物分析
にはグロー放電質量分析法を使用した。表３に示すよう
に、原料Pd中のNaは、0.05mass ppm前後と微量である
が、さらに水素雰囲気中アーク溶解を経ることで、0.00
3mass ppm (3 mass ppb)程度にまで減少した。同様に、
Fe, Niなど鉄族の金属不純物は、２〜５ mass ppm から
0.05 mass ppm 以下に、またＵ，Thも 0.001 mass ppm
(1 mass ppb)以下の極微量にまで低減できた。このこと
から、単一の溶解工程により、各金属不純物が極低濃度
にまで減少し、高純度のPd回収が可能であることが確か
められた。Example 4 A gas supply port and a gas discharge port were installed in a small arc melting furnace, and a 50% H 2 -Ar mixed gas was supplied into the arc melting furnace at a rate of 5 liters per minute while having a nominal purity of 99.95%. Arc melting was performed in a hydrogen atmosphere of relatively high-purity Pd and about 25 g. Table 3
Indicates the concentration of metal impurities in the raw material Pd and the concentration of each metal impurity in Pd after a dissolution time of 60 minutes. In addition, glow discharge mass spectrometry was used for metal impurity analysis. As shown in Table 3, the amount of Na in the raw material Pd is as small as about 0.05 mass ppm.
It decreased to about 3 mass ppm (3 mass ppb). Similarly,
Iron group metal impurities such as Fe and Ni are from 2 to 5 mass ppm
0.05 mass ppm or less, and 0.001 mass ppm for U and Th
(1 mass ppb) or less. From these results, it was confirmed that each metal impurity was reduced to an extremely low concentration by a single dissolution step, and high-purity Pd recovery was possible.
【００１９】[0019]
【表３】 [Table 3]
【００２０】[0020]
【発明の効果】以上説明したように、本発明によれば、
高融点金属や貴金属に含まれる金属不純物を、単一溶解
工程で短時間の内に極低濃度にまで除去することがで
き、高融点金属および貴金属等の高純度化法として有効
である。しかも、本発明は粗金属からの高純度金属の回
収法としても効果的であり、産業上極めて有用と言え
る。As described above, according to the present invention,
Metal impurities contained in high melting point metals and noble metals can be removed to an extremely low concentration in a short time in a single melting step, and this is effective as a method for purifying high melting point metals and noble metals. Moreover, the present invention is also effective as a method for recovering high-purity metals from crude metals, and can be said to be extremely useful in industry.
【図１】１mass％のFe不純物を含むZrを、水素プラズマ
アーク溶解したときのFe濃度の溶解時間に対する変化を
示すグラフ。FIG. 1 is a graph showing a change in Fe concentration with respect to a melting time when Zr containing 1 mass% Fe impurity is melted by a hydrogen plasma arc.
フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) C22B 9/00 - 9/22 C22B 34/24 C22B 34/30 Continuation of front page (58) Field surveyed (Int. Cl. 6 , DB name) C22B 9/00-9/22 C22B 34/24 C22B 34/30
Claims (4)
びVIa 族に属する高融点金属および貴金属を、5000℃以
上の水素含有高温雰囲気下で、水素プラズマアークまた
は水素雰囲気アークにより、活性水素Ｈを発生させて溶
解することにより、金属不純物を蒸発除去することを特
徴とする高純度金属の製造方法。1. A refractory metal and a noble metal belonging to Group IVa, Va and VIa having a purity of 99% or more are purified at 5000 ° C. or lower.
A method for producing a high-purity metal, characterized in that active hydrogen H is generated and melted by a hydrogen plasma arc or a hydrogen atmosphere arc in a hydrogen-containing high-temperature atmosphere to evaporate and remove metal impurities.
水素プラズマアーク溶解法または水素雰囲気アーク溶解
法である請求項１に記載の精製方法。2. The means for generating active hydrogen H comprises:
The purification method according to claim 1, wherein the method is a hydrogen plasma arc melting method or a hydrogen atmosphere arc melting method.
ク溶解の作動ガスとして、２〜100 ％の水素を含むガス
を使用することを特徴とする請求項１または２に記載の
精製方法。3. The method according to claim 1, wherein a gas containing 2 to 100% of hydrogen is used as a working gas for hydrogen plasma arc melting or hydrogen arc melting.
ク溶解に当たって、炉内圧を３気圧〜10トルに調整する
ことを特徴とする請求項１〜３のいずれか１つに記載の
精製方法。4. The method according to claim 1, wherein the furnace pressure is adjusted to 3 atm to 10 torr during the hydrogen plasma arc melting or the hydrogen arc melting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5239610A JP2981090B2 (en) | 1993-09-27 | 1993-09-27 | Production method of high purity metal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5239610A JP2981090B2 (en) | 1993-09-27 | 1993-09-27 | Production method of high purity metal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0790398A JPH0790398A (en) | 1995-04-04 |
| JP2981090B2 true JP2981090B2 (en) | 1999-11-22 |
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ID=17047309
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|---|---|---|---|
| JP5239610A Expired - Fee Related JP2981090B2 (en) | 1993-09-27 | 1993-09-27 | Production method of high purity metal |
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| Country | Link |
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|---|---|---|---|---|
| JP2002105631A (en) * | 2000-09-28 | 2002-04-10 | Sumitomo Metal Mining Co Ltd | High-purity ruthenium sputtering target and manufacturing method |
| JP4874471B2 (en) * | 2001-04-23 | 2012-02-15 | 住友金属鉱山株式会社 | Method for producing high purity iridium sputtering target |
| CN115449767A (en) * | 2022-09-28 | 2022-12-09 | 昆明理工大学 | Preparation method of fine-grain high-purity nickel target material |
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|---|---|
| JPH0790398A (en) | 1995-04-04 |
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