JP3613443B2

JP3613443B2 - Method for dissolving and extracting tantalum and / or niobium-containing alloys

Info

Publication number: JP3613443B2
Application number: JP37461598A
Authority: JP
Inventors: 阪浩通井; 下正典木; 浜嘉男祖
Original assignee: Mitsui Mining and Smelting Co Ltd
Current assignee: Mitsui Mining and Smelting Co Ltd
Priority date: 1998-12-28
Filing date: 1998-12-28
Publication date: 2005-01-26
Anticipated expiration: 2018-12-28
Also published as: JP2000203841A

Description

【０００１】
【発明の属する技術分野】
本発明は、タンタルおよび／またはニオブ含有合金からこれらの金属元素を経済的に効率よく回収するための溶解抽出方法に関する。ここで、「タンタルおよび／またはニオブ含有合金」とは、「タンタル含有合金」、「ニオブ含有合金」および「タンタルおよびニオブを含有する合金」の三者を総称するものである（以下、本明細書において同様である）。
【０００２】
【従来の技術】
タンタルは、その用途が広く、耐食性、耐熱性に優れているため化学工業用として蒸留塔、オートクレーブ、熱交換器、化学繊維用紡糸ノズルなど各種化学装置に用いられている。また、一般にタンタル酸化皮膜は、弁作用（電極が正極であれば誘電体に動作するが、逆に電極が負極であると誘電体として動作しないという特性、すなわち整流特性）と呼ばれる特性を有しているため電解コンデンサの電極材料として使用され、搬送機器、電子機器、電子制御機器などに用いられている。さらに炭化タンタルは超硬切削工具用材料として、酸化タンタルは光学レンズの添加剤として利用されており、タンタルの重要性は極めて大きく、その需要は増大している。
【０００３】
ニオブは、鋼中の炭素を安定化し、粒間腐食を防ぐ効果があるので鉄鋼添加材として使用されており、これが最大の用途である。また、高圧ナトリウムランプのランプ発光部に付随する導電管としてニオブ合金が実用化されており、さらに超電導材料や超合金の添加元素などに利用されている。
【０００４】
タンタルおよび／またはニオブ含有合金からタンタルやニオプの酸化物を製造する方法はいくつかあるが、フッ化水素酸溶解−溶媒抽出法が一般的である。
【０００５】
タンタル含有合金またはニオブ含有合金のフッ化水素酸あるいはこれと硫酸との混酸による溶解抽出においては、下記の反応式（１）、（２）および（３）に示すように、水素ガスが発生する。
【０００６】

ただし、Ｍは金属元素を表す。
【０００７】
水素ガスは、空気に対して７〜７２％の極めて広範囲の爆発組成を構成するためタンタルおよび／またはニオブ含有合金をフッ化水素酸またはこれと硫酸との混酸で直接溶解抽出する方法は危険であり、安全性の点で問題があった。
【０００８】
これらの問題点を解消するため、従来方法として特公平５−２０４９０号公報および特願平１０−２６３２８８号に記載の方法が提案されている。
特公平５−２０４９０号公報に記載されている方法は、溶解抽出工程における水素の発生を無くして爆発の危険を解消すると共に、ニオブの不働態化を阻止してニオブの回収率を高めることを目的とし、ニオブ含有合金を燃焼酸化した後、フッ化水素酸と硫酸との混酸を用いてニオブを溶解抽出する方法である。
【０００９】
また特願平１０−２６３２８８号に記載の方法は、タンタルおよび／またはニオブ含有合金を燃焼酸化することなくフッ化水素酸またはこれと硫酸との混酸で直接溶解抽出する際、発生する水素ガスを爆発組成以下に抑制し、安全に操業できるようにすることを目的とし、反応槽内の所定量の水中にタンタルおよび／またはニオブ含有合金を所要量投入後、フッ化水素酸またはこれと硫酸との混酸を継続的に添加し、発生する水素ガスを抑制しながら溶解する方法である。
【００１０】
これらの方法は、原料であるタンタルおよび／またはニオブ含有合金の合金構成金属を全て、処理液中に溶解させるため多量のフッ化水素酸を必要とする。また溶媒抽出によりタンタルおよび／またはニオブを回収するに際しては、溶媒抽出工程で析出する恐れのある溶解している不純物金属特に鉄を沈殿、析出させ濾過分離により残渣として除去する必要があるが、その際不純物金属沈殿物側にタンタル、ニオブが一部移行するのでタンタル、ニオブの回収率が低下する。さらに、残渣を洗浄水で洗浄して洗浄水中にタンタル、ニオブを回収すると、溶媒抽出工程に供する処理液量が増加し、溶媒抽出工程での生産効率が低下するなどの課題がある。
【００１１】
そこで、溶解抽出すべきタンタル、ニオブ以外の不純物金属が多い場合、使用するフッ化水素酸の使用量が少なく、ニオブ、タンタルの回収率が高く、生産性が優れたニオブ、タンタルの溶解抽出法の出現が強く求められている。
【００１２】
【発明が解決しようとする課題】
本発明は、フッ化水素酸の使用量が少なく、タンタル、ニオブの回収率を向上させた、生産性の高いタンタルおよび／またはニオブ含有合金の溶解抽出方法を提供することにある。
【００１３】
【課題を解決するための手段】
本発明は、下記の事項をその特徴としている。
タンタルおよび／またはニオブ含有合金中のタンタルおよび／またはニオブをフッ化水素酸またはこれと硫酸との混酸で溶解抽出する方法において、反応槽内の所定量の水中に、粉砕したタンタルおよび／またはニオブ含有合金を所要量投入後、まず苛性ソーダ（ＮａＯＨ）で処理し、処理液を固液分離し、得られた不溶解性生成物をフッ化水素酸以外の鉱酸で処理してタンタル、ニオブ以外の不純物金属を鉱酸中に溶出させ、次いで固液分離を行い、得られた残存する不溶解性生成物をフッ化水素酸またはこれと硫酸との混酸で溶解抽出することを特徴とするタンタルおよび／またはニオブ含有合金の溶解抽出方法。
【００１４】
以下に、本発明を詳細に説明する。
まず、従来のタンタルおよび／またはニオブ含有合金を出発原料として酸化タンタルまたは酸化ニオブを製造する工程を、図１に示す。図１に基づいてニオブ含有合金のうちフェロニオブを原料として使用した一般的な例について説明すると、まず、フェロニオブの溶解率を上げるためにジョークラッシャー等の粗砕機で粗粉砕し、溶解槽に入れて５５％のフッ化水素酸（ＨＦ）で金属成分を溶解する。次に硫酸（Ｈ_２ＳＯ_４）を加えて溶液の酸濃度を調整し、これをフィルタープレスで濾過し、未溶解残渣を濾過して清浄な溶液にして溶媒抽出にかける。次にこの酸濃度が高い水溶液を有機溶媒ＭＩＢＫ（メチルイソブチルケトンの略称）と十分接触させると、ニオブはＭＩＢＫに抽出され、不純物は抽残液に残る。次に、ニオブを含むＭＩＢＫを希硫酸で逆抽出し、精製ニオブ水溶液を得、次いでアンモニア水（ＮＨ_４ＯＨ）を加えて水酸化物の沈殿にし、これを濾過、乾燥し、最後に炉でか焼すれば酸化ニオブが得られる。
【００１５】
本発明は、図１に示す従来工程における、粉砕工程と液調整工程の間の溶解工程の改良に係るものであって、微細化したタンタルおよび／またはニオブ含有合金を苛性ソーダで処理し、次いでフッ化水素酸以外の鉱酸で処理することを特徴とする方法であって、これによって大部分の不純物成分を鉱酸に溶出させ、精製されたタンタルまたはニオブの未溶解物を得ることができる。
【００１６】
本発明に係るタンタルおよび／またはニオブ含有合金の溶解抽出方法の工程図を、図２に示す。タンタルおよび／またはニオブ含有合金として鉄を３０％程度含む原料を使用した例について説明すると、まず出発原料であるＴａ含有フェロニオブ（Ｆｅ−Ｔａ／Ｎｂ）をジョークラッシャで粗砕し、さらに湿式ボールミルで微粉砕し、得られた微細粉末合金を５０〜１００℃の苛性ソーダ水溶液で処理する。苛性ソーダの濃度は好ましくは１００〜６００ｇ／ｌ、より好ましくは３００〜５００ｇ／ｌが適当である。苛性ソーダ水溶液の苛性ソーダ濃度が１００ｇ／ｌ未満では反応に時間がかかりすぎ経済性が悪くなる。一方濃度が６００ｇ／ｌ超では粘度が高く、取扱いが困難となる。苛性ソーダによる合金粉末の処理は、合金構造を破壊し、タンタルおよび／またはニオブは苛性ソーダおよびフッ化水素酸を除く鉱酸に不溶解性の反応生成物となし、またＦｅは苛性ソーダに不溶解性で鉱酸可溶性の反応生成物とし後工程におけるＦｅのフッ化水素酸以外の鉱酸への溶解、すなわち脱Ｆｅを可能とする。ＮａＯＨの一部は、Ｎａ_２ＣＯ_３、ＮａＨＣＯ_３で置き換えることができる。
【００１７】
次いで濾過して処理液を固液分離し、濾液と不溶解性生成物に分ける。不溶解性生成物にはＮａＯＨに溶解しないＴａ，Ｎｂ，Ｆｅなどの反応生成物が存在する。この不溶解性生成物は塩酸や硫酸のフッ化水素酸以外の鉱酸で処理し、大部分の不純物成分であるＦｅなどを鉱酸に溶出させる。この脱Ｆｅ工程ではＦｅは除去されるが、Ｔａ／Ｎｂは未溶解のままである。
【００１８】
その後、この溶液を濾過してＦｅＣｌ_２液あるいはＦｅＳＯ_４の濾過液とＴａ／Ｎｂを含有する未溶解物に分ける。ＦｅＣｌ_２液あるいはＦｅＳＯ_４液は中和され廃さいとなる。一方Ｔａ／Ｎｂを含む未溶解物はフッ化水素酸で、Ｔａ／Ｎｂが溶解され、続いて濾過で溶解残渣が除去され、高品位のＴａ／Ｎｂ液が得られる。このＴａ／Ｎｂ液は、図１に示す液調整工程を経て溶媒抽出工程に移行される。
【００１９】
【実施例】
以下に、本発明を実施例と比較例によりさらに説明する。
実施例１
Ｔａ含有フェロニオブ（Ｆｅ−Ｔａ／Ｎｂ）２００ｇ（Ｆｅ２９％、Ｔａ４．５％、Ｎｂ４１．２％）をジョークラッシャーで粗粉砕し、次いで湿式ボールミルで微粉砕してＦｅ−Ｔａ／Ｎｂのスラリーを得た。このＦｅ−Ｔａ／Ｎｂスラリー（スラリー濃度１０００ｇ／ｌ）とＮａＯＨ水溶液２００ｍｌ（濃度１００ｇ／ｌ）とを反応槽（容量１ｌ）に入れ、攪拌混合しながら液温７５℃に加温した。
【００２０】
次に反応槽に濃度７３５ｇ／ｌのＮａＯＨ２１０ｍｌを１６０分かけて少量ずつ添加した結果、反応槽内のＮａＯＨ換算濃度は４２５ｇ／ｌに達した。ＮａＯＨ添加終了後も２５５分間液温７５℃に保持しながら、攪拌を継続後、全量をフィルタプレスで濾過分離した。得られた不溶解性生成物を反応槽（容量５ｌ）に入れ、次いで４ＮＨ_２ＳＯ_４２０００ｍｌを反応槽に添加し、更にｐＨ１になるようにＨ_２ＳＯ_４を添加し、ｐＨ１に維持しながら、６０分間攪拌を継続し、鉄を硫酸酸性水溶液中に溶解させた。反応終了液をフィルタプレスへ送液し濾過分離して濾液（ＦｅＳＯ_４水溶液）３０００ｍｌ（Ｆｅ１８．８ｇ／ｌ）と未溶解物（脱Ｆｅケーキ）湿量３５２．８ｇ（Ｄｒｙ２１２．０ｇ）を得た。
【００２１】
このようにして得られた脱Ｆｅケーキ２１２．０ｇ（Ｄｒｙベース）を水０．１ｌを張り込んだ反応槽（容量０．５ｌ）に入れ、攪拌しながら、濃度８０％のＨＦ０．１４ｌを少量ずつ添加し、６０℃に加温、温度保持しながら６０分間攪拌を継続し、Ｔａ／ＮｂのＨＦへの溶解抽出を行った。
【００２２】
得られた溶解抽出液を全量を濾紙で濾過して濾液０．４４リットル（Ｎｂ１８５ｇ／ｌ、Ｔａ２０ｇ／ｌ、Ｆｅ２１ｇ／ｌ）と溶解残渣１２．７ｇ（Ｆｅ０．３％、Ｎｂ１３．６％、Ｔａ１．６％）を得た。溶解抽出で回収されたＴａ、Ｎｂの回収率は各々Ｎｂ９７．９％、Ｔａ９７．６％であった。
【００２３】
比較例１
ジョークラッシャで粗粉砕されたＦｅ−Ｔａ／Ｎｂ合金２００ｇを水０．２ｌを張込んだ反応槽（容量１ｌ）に入れ攪拌混合しながら、少量ずつＨＦを添加し、１２時間かけて溶解抽出を行った。使用した５５％ＨＦの量は０．２４ｌであった。
【００２４】
次に得られた溶解抽出液に、Ｈ_２ＳＯ_４を添加し、Ｈ_２ＳＯ_４濃度が４Ｎになるように調整した後、全量フィルタプレスで濾過して濾液１．１ｌ（Ｎｂ７０ｇ／ｌ、Ｔａ７．６ｇ／ｌ、Ｆｅ３０ｇ／ｌ）と溶解残渣１００ｇ（Ｄｒｙベース）を得た。溶解残渣はＦｅ２５．１％、Ｎｂ４．８％、Ｔａ０．６％であり、Ｔａ、Ｎｂの回収率は各Ｎｂ９３．４％、Ｔａ９２．９％であった。
【００２５】
実施例２
ボールミルで微粉砕された各１００ｇのＦｅ−Ｔａ／Ｎｂ合金（Ｆｅ２９％、Ｔａ４．５％、Ｎｂ４１．２％）をＮａＯＨ水溶液中に投入し、ＮａＯＨ処理を行った。ＮａＯＨ処理はＮａＯＨの濃度、添加量、液温、処理時間をいろいろかえて行われた。
【００２６】
上記各条件でのＮａＯＨ処理後、反応終了液を全量フィルタプレスで濾過分離して不溶解性生成物を得た。得られた不溶解性生成物を反応槽（容量３ｌ）に入れＨ_２ＳＯ_４をｐＨ１に維持できるまで添加し、不溶解性生成物中の鉄を硫酸中に溶出させた。その後全量液をフィルタプレスで濾過分離し未溶解物（脱Ｆｅケーキ）を得、各々の脱Ｆｅケーキ中のＦｅ量を分析測定し、脱Ｆｅ率を求めた。
その結果を、表１に示す。
【００２７】
【表１】

【００２８】
実施例３
ボールミルで微粉砕されたＦｅ−Ｔａ／Ｎｂ（Ｆｅ２９％、Ｔａ４．５％、Ｎｂ４１．２％）２５ｋｇを、濃度５００ｇ／ｌの苛性ソーダ水溶液４４ｌ中に少量ずつ添加し、１０時間かけて投入し、液温を７５±５℃に保持しながらＮａＯＨ処理を行った。
【００２９】
Ｆｅ−Ｔａ／Ｎｂ投入完了後のＮａＯＨ処理時間経過毎にサンプルを０．１ｌ採取し、そのサンプルを濾紙で濾過分離し、不溶解性生成物を得、得られた不溶解性生成物を反応槽（容量１ｌ）に入れ、Ｈ_２ＳＯ_４をｐＨ１に維持できるまで添加し、不溶解性生成物中のＦｅを硫酸中に溶出させた。その後全量液を濾紙で濾過分離し、未溶解物（脱Ｆｅケーキ）を得、各々の脱Ｆｅケーキ中のＦｅ量を分析測定した。
その結果を、図３に示す。
【００３０】
実施例４
ボールミルで微粉砕された２５ｋｇのＦｅ−Ｔａ／Ｎｂ（Ｆｅ２９％、Ｔａ４．５％、Ｎｂ４１．２％）を濃度５００ｇ／ｌのＮａＯＨの苛性ソーダ４４ｌ中に少量ずつ添加し、１０時間かけて投入し液温を７５±５℃に保持しながら更に１４時間攪拌を継続した。
【００３１】
上記反応終了液を全量フィルタプレスで濾過し、不溶解性生成物を得、得られた不溶解性生成物を５分割し、各々を反応槽（容量１００ｌ）に入れ、Ｈ_２ＳＯ_４濃度および添加量をかえてＦｅの溶出を行い、フィルタプレスで濾過分離して未溶解物（脱Ｆｅケーキ）を得、得られた脱Ｆｅケーキ中のＦｅ量を分析測定し、Ｆｅ除去率を求めた。
その結果を、図４に示す。
【００３２】
実施例５
実施例４において、Ｈ_２ＳＯ_４の代りにＨＣｌを用いた以外は同様の条件で試験を行った。
ボールミルで微粉砕された２５ｋｇのＦｅ−Ｔａ／Ｎｂ（Ｆｅ２９％、Ｔａ４．５％、Ｎｂ４１．２％）を濃度５００ｇ／ｌのＮａＯＨの苛性ソーダ４４ｌ中に少量ずつ添加し、１０時間かけて投入し、液温を７５±５℃に保持しながら更に１４時間攪拌を継続した。
【００３３】
上記反応終了液を全量フィルタプレスで濾過し、不溶解性生成物を得、得られた不溶解性生成物を５分割し、各々を反応槽（容量１００ｌ）に入れ、ＨＣｌ濃度および添加量をかえてＦｅの溶出を行い、フィルタプレスで濾過分離して未溶解物（脱Ｆｅケーキ）を得、得られた脱Ｆｅケーキ中のＦｅ量を分析測定し、Ｆｅ除去率を求めた。
その結果を、図５に示す。
【００３４】
【発明の効果】
１．従来法は原料合金中のＴａ／Ｎｂ以外の不純物金属も全て、フッ化水素酸またはこれと硫酸との混酸で溶解抽出するので、高価なフッ化水素酸を多量に必要とするが、本発明では、原料合金中の不純物金属を前処理（ＮａＯＨ処理、脱鉄処理）で除去した後、Ｔａ／Ｎｂをフッ化水素酸またはこれと硫酸との混酸で溶解抽出するのでフッ化水素酸の使用量が少ない。特に、Ｆｅ−Ｔａ／Ｎｂ合金の如く、Ｔａ／Ｎｂに比較してＦｅの量が多いものはその効果の差は顕著である。
２．原料中の不純物金属特に鉄は、中和されて廃滓として廃棄されるが、脱Ｆｅ処理工程からのＦｅ含有濾液中には、Ｆが含有されていないため濾液処理に際し、Ｃａ塩によるＦ処理が不要となり、中和された廃滓量は従来法に比べ大幅に減少する。
【００３５】
３．本発明ではＮａＯＨ処理により原料合金中のＴａ／Ｎｂはフッ酸以外の鉱酸には不溶解性の生成物となるため、鉱酸処理ではＦｅ等の不純物のみ溶解抽出されるため不純物側へのＴａ／Ｎｂの移行がなくＴａ／Ｎｂの回収率を高めることができる。
４．Ｔａ／Ｎｂの不純物側への移行がなく、従来行われていたＦｅ等の不純物残渣へ移行したＴａ／Ｎｂの回収のための残渣洗浄に伴う回収水の発生がなく溶媒抽出工程へ通す液中のＴａ／Ｎｂの濃度が高くなり、生産性が向上する。
５．ＮａＯＨ処理後の濾過工程の濾液は、不純物をあまり含まないのでＮａＯＨ処理工程で使用するＮａＯＨ溶解用の用水として、あるいはＦｅ塩溶液の排水処理用中和剤しとて再利用できる。
【図面の簡単な説明】
【図１】従来のタンタルおよび／またはニオブ含有合金からの酸化焙焼法による酸化タンタル／酸化ニオブを製造する工程図である。
【図２】本発明の鉄含有タンタル／ニオブ合金の溶解抽出方法の工程図である。
【図３】本発明の実施例３におけるＮａＯＨ処理でのＦｅ−Ｔａ／Ｎｂ合金投入終了からの時間と脱Ｆｅ品のＦｅ含有率との関係を示すグラフである。
【図４】実施例４におけるＨ_２ＳＯ_４使用当量とＦｅ除去率との関係を示すグラフである。
【図５】実施例５におけるＨＣｌ使用当量とＦｅ除去率との関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solution extraction method for economically and efficiently recovering these metal elements from tantalum and / or niobium-containing alloys. Here, the “tantalum and / or niobium-containing alloy” is a collective term for the “tantalum-containing alloy”, “niobium-containing alloy”, and “alloy containing tantalum and niobium” (hereinafter referred to as the present specification). The same in the book) .
[0002]
[Prior art]
Tantalum has a wide range of uses and is excellent in corrosion resistance and heat resistance. Therefore, tantalum is used in various chemical apparatuses such as distillation towers, autoclaves, heat exchangers and chemical fiber spinning nozzles for the chemical industry. In general, a tantalum oxide film has a characteristic called valve action (a characteristic that operates as a dielectric when the electrode is a positive electrode, but does not operate as a dielectric when the electrode is a negative electrode, that is, a rectifying characteristic). Therefore, it is used as an electrode material for electrolytic capacitors, and is used in conveying equipment, electronic equipment, electronic control equipment, and the like. Furthermore, tantalum carbide is used as a material for carbide cutting tools, and tantalum oxide is used as an additive for optical lenses. The importance of tantalum is extremely large, and its demand is increasing.
[0003]
Niobium is used as a steel additive because it has the effect of stabilizing the carbon in the steel and preventing intergranular corrosion, and this is the largest application. In addition, niobium alloys have been put into practical use as conductive tubes associated with the lamp light emitting part of high-pressure sodium lamps, and are further used as superconducting materials and superalloy additive elements.
[0004]
There are several methods for producing tantalum and / or niop oxides from tantalum and / or niobium-containing alloys, but the hydrofluoric acid dissolution-solvent extraction method is common.
[0005]
In dissolution extraction of a tantalum-containing alloy or niobium-containing alloy with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid, as shown in the following reaction formulas (1), (2) and (3), hydrogen gas is generated. .
[0006]

However, M represents a metal element.
[0007]
Since hydrogen gas constitutes an extremely wide range of explosive composition of 7 to 72% with respect to air, it is dangerous to directly dissolve and extract tantalum and / or niobium-containing alloys with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid. There was a problem in terms of safety.
[0008]
In order to solve these problems, methods described in Japanese Patent Publication No. 5-20490 and Japanese Patent Application No. 10-263288 have been proposed as conventional methods.
The method described in Japanese Patent Publication No. 5-20490 eliminates the risk of explosion by eliminating the generation of hydrogen in the dissolution and extraction process, and increases the recovery rate of niobium by preventing the passivation of niobium. The purpose is a method in which niobium-containing alloy is burnt and oxidized, and then niobium is dissolved and extracted using a mixed acid of hydrofluoric acid and sulfuric acid.
[0009]
In addition, the method described in Japanese Patent Application No. 10-263288 is a method in which hydrogen gas generated when a tantalum and / or niobium-containing alloy is directly dissolved and extracted with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid without combustion oxidation. The purpose is to suppress the explosion composition to below the level and to enable safe operation. After adding a required amount of tantalum and / or niobium-containing alloy into a predetermined amount of water in the reaction vessel, hydrofluoric acid or this and sulfuric acid In this method, the mixed acid is continuously added and dissolved while suppressing the generated hydrogen gas.
[0010]
These methods require a large amount of hydrofluoric acid in order to dissolve all the alloy constituent metals of the tantalum and / or niobium-containing alloy as raw materials in the treatment liquid. Moreover, when recovering tantalum and / or niobium by solvent extraction, it is necessary to precipitate and deposit dissolved impurity metals, especially iron, which may be precipitated in the solvent extraction step, and remove them as residues by filtration separation. At this time, since tantalum and niobium partially migrate to the impurity metal precipitate side, the recovery rate of tantalum and niobium decreases. Furthermore, when the residue is washed with washing water and tantalum and niobium are collected in the washing water, there are problems such as an increase in the amount of processing liquid used in the solvent extraction step and a decrease in production efficiency in the solvent extraction step.
[0011]
Therefore, when there are many impurity metals other than tantalum and niobium to be dissolved and extracted, the amount of hydrofluoric acid to be used is small, the niobium and tantalum recovery rate is high, and the niobium and tantalum dissolution and extraction methods have excellent productivity. The emergence of is strongly demanded.
[0012]
[Problems to be solved by the invention]
It is an object of the present invention to provide a high-productivity tantalum and / or niobium-containing alloy dissolution and extraction method that uses less hydrofluoric acid and improves the recovery rate of tantalum and niobium.
[0013]
[Means for Solving the Problems]
The present invention has the following features.
In a method of dissolving and extracting tantalum and / or niobium in a tantalum and / or niobium-containing alloy with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid, pulverized tantalum and / or niobium in a predetermined amount of water in a reaction vessel After the required amount of alloy is added, it is first treated with caustic soda (NaOH), the treatment liquid is separated into solid and liquid, and the resulting insoluble product is treated with a mineral acid other than hydrofluoric acid to remove tantalum and niobium. The tantalum is characterized in that the impurity metal is eluted in mineral acid, followed by solid-liquid separation, and the remaining insoluble product obtained is dissolved and extracted with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid. And / or a method for dissolving and extracting a niobium-containing alloy.
[0014]
The present invention is described in detail below.
First, a process for producing tantalum oxide or niobium oxide using a conventional tantalum and / or niobium-containing alloy as a starting material is shown in FIG. A general example in which ferroniobium is used as a raw material among niobium-containing alloys will be described with reference to FIG. 1. First, in order to increase the dissolution rate of ferroniobium, it is roughly crushed by a crusher such as a jaw crusher and put in a melting tank. Dissolve the metal component with 55% hydrofluoric acid (HF). Next, sulfuric acid (H ₂ SO ₄ ) is added to adjust the acid concentration of the solution, this is filtered with a filter press, and the undissolved residue is filtered to form a clean solution and subjected to solvent extraction. Next, when this aqueous solution having a high acid concentration is sufficiently brought into contact with the organic solvent MIBK (abbreviation for methyl isobutyl ketone), niobium is extracted into MIBK and impurities remain in the extraction residue. Next, MIBK containing niobium is back-extracted with dilute sulfuric acid to obtain a purified niobium aqueous solution, followed by addition of aqueous ammonia (NH ₄ OH) to precipitate a hydroxide, which is filtered and dried, and finally is heated in a furnace. If calcined, niobium oxide is obtained.
[0015]
The present invention relates to an improvement in the melting step between the pulverization step and the liquid adjustment step in the conventional step shown in FIG. 1, and the refined tantalum and / or niobium-containing alloy is treated with caustic soda, and then fluorinated. The method is characterized by treating with a mineral acid other than hydrofluoric acid, whereby most of the impurity components can be eluted into the mineral acid to obtain purified undissolved tantalum or niobium.
[0016]
FIG. 2 shows a process chart of the method for dissolving and extracting tantalum and / or niobium-containing alloys according to the present invention. An example of using a raw material containing about 30% iron as a tantalum and / or niobium-containing alloy will be described. First, Ta-containing ferroniobium (Fe—Ta / Nb), which is a starting material, is roughly crushed with a jaw crusher, The fine powder alloy obtained by pulverization is treated with an aqueous caustic soda solution at 50 to 100 ° C. The concentration of caustic soda is preferably 100 to 600 g / l, more preferably 300 to 500 g / l. If the concentration of caustic soda in the aqueous caustic soda solution is less than 100 g / l, the reaction takes too much time and the economy becomes worse. On the other hand, if the concentration exceeds 600 g / l, the viscosity is high and handling becomes difficult. Treatment of the alloy powder with caustic soda destroys the alloy structure, tantalum and / or niobium is not a reaction product insoluble in mineral acids except caustic soda and hydrofluoric acid, and Fe is insoluble in caustic soda. As a reaction product soluble in mineral acid, it is possible to dissolve Fe in a mineral acid other than hydrofluoric acid in the subsequent step, that is, to remove Fe. A part of NaOH can be replaced with Na ₂ CO ₃ or NaHCO ₃ .
[0017]
Subsequently, the treatment liquid is separated into solid and liquid by filtration, and separated into a filtrate and an insoluble product. Insoluble products include reaction products such as Ta, Nb, and Fe that are not soluble in NaOH. This insoluble product is treated with a mineral acid other than hydrofluoric acid such as hydrochloric acid or sulfuric acid, and most impurities such as Fe are eluted into the mineral acid. In this Fe removal step, Fe is removed, but Ta / Nb remains undissolved.
[0018]
Thereafter, this solution is filtered and divided into an FeCl ₂ liquid or FeSO ₄ filtrate and an undissolved material containing Ta / Nb. The FeCl ₂ liquid or FeSO ₄ liquid is neutralized and discarded. On the other hand, the undissolved material containing Ta / Nb is hydrofluoric acid, and Ta / Nb is dissolved. Subsequently, the dissolution residue is removed by filtration to obtain a high-quality Ta / Nb solution. This Ta / Nb liquid is transferred to the solvent extraction process through the liquid adjustment process shown in FIG.
[0019]
【Example】
Hereinafter, the present invention will be further described with reference to examples and comparative examples.
Example 1
200 g (Fe 29%, Ta 4.5%, Nb 41.2%) of Ta-containing ferroniobium (Fe-Ta / Nb) is coarsely pulverized with a jaw crusher and then finely pulverized with a wet ball mill to obtain a Fe-Ta / Nb slurry. It was. The Fe-Ta / Nb slurry (slurry concentration 1000 g / l) and NaOH aqueous solution 200 ml (concentration 100 g / l) were placed in a reaction vessel (capacity 1 l) and heated to 75 ° C. while stirring and mixing.
[0020]
Next, 210 ml of NaOH having a concentration of 735 g / l was added to the reaction vessel little by little over 160 minutes. As a result, the NaOH equivalent concentration in the reaction vessel reached 425 g / l. The stirring was continued while maintaining the liquid temperature at 75 ° C. for 255 minutes even after the end of the addition of NaOH, and then the entire amount was separated by filtration with a filter press. The obtained insoluble product was put into a reaction vessel (volume: 5 l), and then 2000 ml of 4NH ₂ SO ₄ was added to the reaction vessel, and H ₂ SO ₄ was added so that the pH was 1, and the pH was maintained at 1. Stirring was continued for 60 minutes, and iron was dissolved in an aqueous sulfuric acid solution. The reaction-terminated liquid was sent to a filter press and filtered and separated to obtain 3000 ml (Fe 18.8 g / l) of filtrate (FeSO ₄ aqueous solution) and 352.8 g (Dry 212.0 g) of undissolved (de-Fe cake) moisture. .
[0021]
212.0 g (Dry base) of the de-fe cake thus obtained was placed in a reaction tank (volume 0.5 l) filled with 0.1 l of water, and 0.14 l of 80% HF was added in a small amount while stirring. While stirring at 60 ° C. and stirring for 60 minutes, Ta / Nb was dissolved and extracted in HF.
[0022]
The total amount of the resulting dissolved extract was filtered through filter paper, and 0.44 liters of filtrate (Nb 185 g / l, Ta 20 g / l, Fe 21 g / l) and 12.7 g of dissolved residue (Fe 0.3%, Nb 13.6%, Ta1) .6%). The recovery rates of Ta and Nb recovered by dissolution extraction were Nb 97.9% and Ta 97.6%, respectively.
[0023]
Comparative Example 1
200 g of Fe-Ta / Nb alloy coarsely pulverized with a jaw crusher was placed in a reaction tank (volume 1 l) filled with 0.2 l of water, and HF was added in small portions while stirring and mixing. went. The amount of 55% HF used was 0.24 l.
[0024]
Next, H ₂ SO ₄ was added to the obtained dissolved extract, and the H ₂ SO ₄ concentration was adjusted to 4N, followed by filtration with a filter press in a total amount of 1.1 l (Nb 70 g / l, Ta7 0.6 g / l, Fe 30 g / l) and 100 g of dissolution residue (Dry base). The dissolution residues were Fe 25.1%, Nb 4.8%, and Ta 0.6%, and the recovery rates of Ta and Nb were Nb 93.4% and Ta 92.9%, respectively.
[0025]
Example 2
Each 100 g of Fe—Ta / Nb alloy (Fe 29%, Ta 4.5%, Nb 41.2%) finely pulverized by a ball mill was put into a NaOH aqueous solution and subjected to NaOH treatment. The NaOH treatment was performed by changing the concentration of NaOH, the amount added, the liquid temperature, and the treatment time.
[0026]
After the NaOH treatment under each of the above conditions, the reaction-completed liquid was filtered and separated with a filter press to obtain an insoluble product. The obtained insoluble product was put into a reaction vessel (volume: 3 l), and H ₂ SO ₄ was added until pH 1 could be maintained, and iron in the insoluble product was eluted in sulfuric acid. Thereafter, the whole liquid was filtered and separated with a filter press to obtain an undissolved product (de-Fe cake), and the amount of Fe in each de-Fe cake was analyzed and measured to obtain the de-Fe rate.
The results are shown in Table 1.
[0027]
[Table 1]

[0028]
Example 3
25 kg of Fe-Ta / Nb (Fe 29%, Ta 4.5%, Nb 41.2%) finely pulverized by a ball mill was added little by little into 44 l of an aqueous caustic soda solution having a concentration of 500 g / l, and charged over 10 hours. NaOH treatment was performed while maintaining the liquid temperature at 75 ± 5 ° C.
[0029]
0.1 l of a sample is taken every time NaOH treatment time has elapsed after the completion of Fe-Ta / Nb input, the sample is filtered and separated with a filter paper, an insoluble product is obtained, and the obtained insoluble product is reacted. placed in a bath (capacity _1l), it was added until maintain H 2 SO ₄ to pH 1, the Fe of insoluble product was eluted in the sulfuric acid. Thereafter, the whole liquid was separated by filtration with filter paper to obtain an undissolved product (de-Fe cake), and the amount of Fe in each de-Fe cake was analyzed and measured.
The result is shown in FIG.
[0030]
Example 4
25 kg of Fe-Ta / Nb (Fe 29%, Ta 4.5%, Nb 41.2%) finely pulverized by a ball mill is added little by little into 44 l of caustic soda having a concentration of 500 g / l and charged over 10 hours. Stirring was continued for another 14 hours while maintaining the liquid temperature at 75 ± 5 ° C.
[0031]
The reaction completion liquid is filtered through a filter press to obtain an insoluble product. The obtained insoluble product is divided into 5 parts, each is put into a reaction vessel (capacity 100 l), and the H ₂ SO ₄ concentration and Elution of Fe was carried out by changing the amount added, and an undissolved product (de-Fe cake) was obtained by filtration and separation with a filter press, and the amount of Fe in the obtained de-Fe cake was analyzed and measured to determine the Fe removal rate. .
The result is shown in FIG.
[0032]
Example 5
In Example 4, the test was performed under the same conditions except that HCl was used instead of H ₂ SO ₄ .
25 kg of Fe-Ta / Nb (Fe 29%, Ta 4.5%, Nb 41.2%) finely pulverized by a ball mill is added little by little into 44 l of caustic soda having a concentration of 500 g / l and charged over 10 hours. The mixture was further stirred for 14 hours while maintaining the liquid temperature at 75 ± 5 ° C.
[0033]
The reaction completion liquid is filtered through a filter press to obtain an insoluble product. The obtained insoluble product is divided into 5 parts, each is put into a reaction vessel (capacity 100 l), and the HCl concentration and the added amount are adjusted. Instead, Fe was eluted and separated by filtration with a filter press to obtain an undissolved product (de-Fe cake). The amount of Fe in the obtained de-Fe cake was analyzed and measured to obtain the Fe removal rate.
The result is shown in FIG.
[0034]
【The invention's effect】
1. In the conventional method, since all impurity metals other than Ta / Nb in the raw material alloy are dissolved and extracted with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid, a large amount of expensive hydrofluoric acid is required. Then, after removing the impurity metal in the raw material alloy by pretreatment (NaOH treatment, deironation treatment), Ta / Nb is dissolved and extracted with hydrofluoric acid or a mixed acid of this and sulfuric acid. The amount is small. In particular, the difference in the effect is remarkable when the amount of Fe is larger than that of Ta / Nb, such as Fe-Ta / Nb alloy.
2. Impurity metals in the raw material, especially iron, are neutralized and discarded as waste. However, since Fe is not contained in the Fe-containing filtrate from the de-Fe treatment process, F treatment with Ca salt is performed during the filtrate treatment. The amount of neutralized waste is greatly reduced compared to the conventional method.
[0035]
3. In the present invention, since the Ta / Nb in the raw material alloy is insoluble in mineral acids other than hydrofluoric acid by NaOH treatment, only impurities such as Fe are dissolved and extracted in the mineral acid treatment. There is no transition of Ta / Nb, and the recovery rate of Ta / Nb can be increased.
4). There is no transfer to the impurity side of Ta / Nb, and there is no generation of recovered water due to residue cleaning for recovery of Ta / Nb transferred to impurity residues such as Fe, which has been performed in the past. This increases the Ta / Nb concentration and improves the productivity.
5. Since the filtrate of the filtration process after NaOH treatment does not contain much impurities, it can be reused as water for dissolving NaOH used in the NaOH treatment process or as a neutralizer for wastewater treatment of Fe salt solution.
[Brief description of the drawings]
FIG. 1 is a process diagram for producing tantalum oxide / niobium oxide from a conventional tantalum and / or niobium-containing alloy by oxidation roasting.
FIG. 2 is a process diagram of a method for dissolving and extracting an iron-containing tantalum / niobium alloy according to the present invention.
FIG. 3 is a graph showing the relationship between the time from the completion of Fe—Ta / Nb alloy addition in NaOH treatment in Example 3 of the present invention and the Fe content of a Fe-free product.
4 is a graph showing the relationship between the equivalent amount of H ₂ SO ₄ used and the Fe removal rate in Example 4. FIG.
5 is a graph showing the relationship between the equivalent amount of HCl used and the Fe removal rate in Example 5. FIG.

Claims

In a method of dissolving and extracting tantalum in a tantalum-containing alloy with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid, after the tantalum-containing alloy pulverized into water in a reaction vessel is charged, it is first treated with caustic soda, Solid-liquid separation, the resulting insoluble product was treated with a mineral acid other than hydrofluoric acid to elute impurity metals other than tantalum into the mineral acid, then solid-liquid separation was performed, and the resulting residue A method for dissolving and extracting a tantalum-containing alloy, wherein the insoluble product is dissolved and extracted with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid.

In a method of dissolving and extracting niobium in a niobium-containing alloy with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid, after the niobium-containing alloy pulverized in water in a reaction vessel is charged, the niobium-containing alloy is first treated with caustic soda. Solid-liquid separation, the resulting insoluble product was treated with a mineral acid other than hydrofluoric acid to elute impurity metals other than niobium into the mineral acid, followed by solid-liquid separation, and the resulting residue A method for dissolving and extracting a niobium-containing alloy, wherein the insoluble product is dissolved and extracted with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid.

In the method of dissolving and extracting tantalum and niobium in an alloy containing tantalum and niobium with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid, the alloy containing tantalum and niobium pulverized in water in the reaction vessel is charged. After treatment with caustic soda, the treatment liquid is separated into solid and liquid, and the resulting insoluble product is treated with a mineral acid other than hydrofluoric acid to elute impurity metals other than tantalum and niobium into the mineral acid. Then, solid-liquid separation is performed, and the obtained remaining insoluble product is dissolved and extracted with hydrofluoric acid or a mixed acid of sulfuric acid and sulfuric acid. Method.