JP4418129B2

JP4418129B2 - Collection method of valuable metals

Info

Publication number: JP4418129B2
Application number: JP2001175346A
Authority: JP
Inventors: 清隆安田; 実酒井
Original assignee: Mitsui Mining and Smelting Co Ltd
Current assignee: Mitsui Kinzoku Co Ltd
Priority date: 2001-03-02
Filing date: 2001-06-11
Publication date: 2010-02-17
Anticipated expiration: 2021-06-11
Also published as: JP2002327215A

Description

【０００１】
【発明の属する技術分野】
本発明は、有価金属含有廃材から有価金属を高純度で簡便かつ安価に回収する方法に関し、より詳細には廃ニッケル−水素二次電池からニッケル、コバルト及び希土類金属等の有価金属を回収する方法に関する。
【０００２】
【従来の技術】
廃ニッケル−水素二次電池から有価金属であるニッケル、コバルト及び希土類金属等を回収する方法として、廃ニッケル−水素二次電池を破砕、解砕、篩分し、粗粒部（プラスチック、鉄、発泡ニッケル等）と、細粒部（水酸化ニッケル、水素吸蔵合金）とに分離し、細粒部をアルカリ金属を含んだ硫酸で溶解し、コバルト含有ニッケル溶解液から不純物を除去した後、電解処理して金属ニッケル及びニッケル−コバルト合金を回収する方法が提案されている（特開平９−82371号公報）。しかしこの方法は、ニッケル等の有価金属の回収工程が極めて複雑であるという問題がある。
【０００３】
有価金属含有廃材からの有価金属回収では、単に回収効率を上げることや前述した回収工程を複雑にしないこと以外に、回収される有価金属中の炭素含有量を少なくすることを考慮する必要があり、これにより回収有価金属の用途が広くなるという利点がある。回収後に低炭素化を行っても良いが工程の追加は時間的及びコスト的に望ましくない。
従って例えば特開2000−67935公報では、廃ニッケル−水素二次電池を破砕、解砕、篩分し、有価物を回収する有価物分別処理工程と、該有価物を酸化雰囲気中で加熱する酸化処理工程と、還元雰囲気中で加熱溶融して溶融金属とする還元−溶融工程特許から成る廃ニッケル−水素二次電池からの有価物の回収方法が開示され、前記酸化処理工程で含有炭素を酸化により除去することが試みられている。
【０００４】
【発明が解決しようとする課題】
この方法では、高温で行われる酸化処理工程で確かに有価物中の炭素含有量は低減するが、同時に有価金属であるニッケル、コバルト及希土類金属等が酸化されるため、効率的な有価金属の回収方法とはいい難い。
このように従来の有価金属の回収方法では、廃ニッケル−水素二次電池等の有価金属含有廃材に含まれる炭素が回収後の有価金属中に残存し、又この残存炭素量を低減すると、得られる有価金属が酸化されてしまい、所望の有価金属が得られなくなるという欠点がある。
本発明は、このような従来技術の欠点を解消し、有価金属を実質的に酸化することなく、炭素含有量が低減した有価金属を回収できる方法を提供することを目的とする。
【０００５】
【課題を解決するための手段】
本発明方法は、有価金属含有廃材から有価物を回収する工程と、回収した有価物を非酸化性雰囲気で加熱して炭素を除去する脱炭素工程とを含んで成ることを特徴とする有価金属の回収方法であり、脱炭素工程後に、脱炭素した有価金属を加熱溶融して溶融金属とする溶融工程を追加しても良い。
【０００６】
以下本発明を詳細に説明する。
本発明方法は、有価金属含有廃材から回収した有価物を非酸化性雰囲気で加熱して実質的に前記有価物中の有価金属を酸化することなく炭素を除去することを特徴とする。なお本発明で有価物とは回収すべき有価金属を含む組成物を意味し、場合によっては回収された有価金属を意味することもある。
又本発明方法の対象となる有価金属含有廃材としては、廃ニッケル−水素二次電池の他に廃ニッケル−カドミウム電池及び廃リチウムイオン電池等がある。
【０００７】
次に本発明方法を、廃ニッケル−水素二次電池等の電池廃材に適用した例を図面に基づいて説明する。
図１は本発明方法を廃ニッケル−水素二次電池からの有価金属回収に適用した実施態様を示すフローチャートである。
本発明方法の第１段階である有価物回収工程は、従来方法と同様に行えば良く、図示の通り有価金属含有廃材が廃ニッケル−水素二次電池の場合は、例えば該電池を剪断破砕機を用いて破砕し、解砕機を用いて湿式法で解砕を行い、篩等で分級する。篩の上に残った非分級物を磁力選別してプラスチック、紙等の非着磁物を除去した後、微量のプラスチック及び紙等を燃焼し除去する。
【０００８】
この他に例えば電池の極板に発泡ニッケルを使用している場合は、極板をそのまま水素還元して又は不活性ガス雰囲気中で加熱処理して有価物を回収しても良い。
このようにして得られる有価物は、有価金属含有廃材が廃ニッケル−水素二次電池の場合、主としてニッケル等の正極主体回収物及び水素吸蔵合金等の負極主体回収物を含み、この他に有機バインダーと所定量の炭素が含まれる。
次いでこれらの物理的に分別された有価物を、非酸化性雰囲気中で加熱処理し、有価物中に含まれる炭素を酸化して少なくともその一部を除去する（脱炭素工程）。
【０００９】
非酸化性雰囲気とは、加熱により、実質的に金属や合金を酸化することなく炭素を還元等により除去できる雰囲気を意味し、不活性ガス雰囲気、水素ガス雰囲気、水蒸気雰囲気、不活性ガス−水蒸気雰囲気及び不活性ガス−水蒸気−水素ガス雰囲気から選択される。不活性ガスには、アルゴン、窒素及びヘリウム等が含まれ、非酸化性雰囲気としては還元雰囲気である水素ガス雰囲気が特に好ましい。
脱炭素工程における加熱条件は、好ましくは350〜1050℃で５分〜10時間、より好ましくは400〜750℃で30分〜５時間である。加熱温度が350℃未満であると有価物中に含まれる金属化合物例えば水酸化ニッケルの縮合脱水分解が起こらず、
かつ反応速度も遅く回収率が低くなる。又加熱温度が1050℃を超えても処理効率が著しく向上する訳ではなく、金属回収のエネルギー効率が低下する。
【００１０】
不活性ガス雰囲気下での加熱処理により、回収された有価物中に含まれる酸素、水素及び水蒸気が還元的又は酸化的に少なくとも一部の炭素の除去に寄与すると同時に、劣化金属酸化物の一部が金属に還元される。
水素ガス雰囲気では有価物中の少なくとも一部の炭素が水素により還元されて低級炭化水素等に転化され有価物から除去される。
更に水蒸気雰囲気では、有価物中の少なくとも一部の炭素が水蒸気による変性を受け、又は水蒸気で還元されて有価物中から除去される。
【００１１】
このようにして脱炭素工程で有価物中の少なくとも一部の炭素を除去された有価物は有価金属に変換され、脱炭素工程の加熱を停止することにより、冷却されて固体の金属として回収できる。
用途によっては溶融金属として回収することが望ましい場合もあり、その際は脱炭素工程における加熱に引き続いて又は一旦加熱を停止した後に、回収した有価金属の加熱を行って溶融金属として回収すれば良い（溶融工程）。
溶融工程における加熱雰囲気と有価金属の酸化を抑制するために、アルゴン中等の不活性ガス雰囲気が好ましい。
【００１２】
このような構成を含んで成る本発明方法では、脱炭素工程を不活性ガス雰囲気で行うと、有価金属含有廃材中に含まれる水素や酸素を有効に利用し、ミッシュメタル等の酸化され易い金属を実質的に酸化させることなく、該廃材中に含まれる少なくとも一部の炭素を除去できる。
又脱炭素工程を水素ガス雰囲気で行うと、雰囲気中の水素が有価金属含有廃材中に含まれる炭素を還元的に除去し、ミッシュメタル等の酸化され易い金属を実質的に酸化させることなく、該廃材中に含まれる少なくとも一部の炭素を除去できる。
【００１３】
又脱炭素工程を水蒸気雰囲気で行うと、有価金属含有廃材中に含まれる炭素が還元又は変性により除去され、ミッシュメタル等の酸化され易い金属を実質的に酸化させることなく、該廃材中に含まれる少なくとも一部の炭素を除去できる。このように脱炭素工程を行うことにより、実質的に酸化反応を伴わず、比較的低温で有価物中の炭素を1000ppm（0.1重量％）以下、条件に依っては100ppm（0.01重量％）以下に低減することができる。
【００１４】
従来のように回収された有価物の酸化処理を行えば炭素は容易に除去できるが、
他の金属成分例えばニッケル、コメントあるいはミッシュメタルが酸化され、この酸化メタルを還元するために莫大なエネルギーを必要とし効率が悪いという問題点があった。
これに対し、本発明方法によると、脱炭素工程を採用することにより、金属成分の酸化を伴うことなく、有価物中の炭素除去が可能になり、得られる有価金属含有廃材の再還元といった工程が不要になり、簡便に有価金属含有廃材から有価金属を回収できる。
実際の操業では通常廃材からのスラグが回収有価金属中に含まれ、有価金属とスラグの混合物として得られるが、この混合物にフラックスを添加して加熱すると、比重の大きい溶融金属と比重の小さい溶融スラグに分離するため、比較的容易に高純度の有価金属を回収できる。
【００１５】
【発明の実施の形態】
本発明に係わる有価金属の回収方法の実施例を記載するが、本発明は該実施態様に限定されるものではない。
【００１６】
【実施例】
次に本発明方法を実施例に基づきより具体的に説明する。
（有価物回収工程）
廃ニッケル−水素電池を剪断破砕機（ドイツのAlpine A.G.製のRotoplex Cutting Mill）を用いて、乾式の破砕を行った。次いで解砕機（Attriction Machine）を用いて、湿式法で解砕を行い、水洗によりプラスチック、紙などを除去し、その後篩（28メッシュ）で分級した。この分級物は負極の水素吸蔵合金が濃縮した負極主体の回収物であった。篩上の非分級物を2000〜3000ガウスで磁力選別して負極Ｆｅ基板を除去した。Ｆｅ基板が除去された正極主体の混合物を振動ミル（川崎重工業株式会社製「T−100型」を用いて粉砕し、篩（24メッシュ）で分級することにより、基板の発泡Ｎｉと正極活物質の水酸化ニッケルを主体とした正極主体とした正極主体回収物を得た。
【００１７】
一方解砕機で湿式解砕及び分級により得られた28メッシュ篩下の分級物にも、電池の活物質であるニッケル−水素及び水酸化ニッケル等の有価物が濃縮されていた。このようにして得られた有価物を負極主体回収物及び正極主体回収物に大別し、更に両者を混合して正負極混合物を調製した。
次いでこのようにして得られた負極主体回収物（実施例１〜13）、正極主体回収物（実施例14〜26）及び正負極混合物（実施例27〜32）のそれぞれについて脱炭素工程及び溶融工程を行い、得られた有価金属中の炭素量及び酸素量を測定した。
【００１８】
実施例１
有価物回収工程で得られた負極主体回収物（炭素含有量：1.27重量％及び酸素含有量6.5重量％）３ｇを雰囲気中にアルゴンガスを200cc／分で流しながら400℃で1時間脱炭素処理を行い（脱炭素工程）、更にアルゴン雰囲気中、1400℃で1時間加熱溶融して溶媒金属として回収した。得られた溶融金属中の炭素含有量及び酸素含有量はそれぞれ0.93重量％及び6.5重量％に減少した。この結果を表１に示した。
【００１９】
実施例２〜７
実施例１と同じ組成の負極主体回収物を、表１に示す温度及び加熱時間で、かつ雰囲気ガスを流しながら脱炭素処理を行い、更に実施例１と同様の条件で加熱溶融を行った。処理により得られた溶融金属中の炭素含有量及び酸素含有量を表１に示した。なお水素ガス雰囲気での試験の場合は、脱炭素工程における所定の反応時間終了後、気流ガスをアルゴンガスに置換した後、冷却した。又表中のAr(H₂O)は水蒸気で飽和したアルゴンガスを示す。
【００２０】
実施例８〜 13
実施例１と同じ組成の負極主体回収物を、表１に示す温度及び加熱時間で、かつ雰囲気ガスを流し更に前記負極主体回収物を回転（攪拌）させながら脱炭素処理を行い、次いで実施例１と同様の条件で加熱溶融を行った。処理により得られた溶融金属中の炭素含有量及び酸素含有量を表１に示した。
【００２１】
実施例１〜 13 の考察
実施例１〜13の実験結果から、脱炭素工程を行うことにより、全ての実施例で炭素含有量及び酸素含有量が減少したことが分かる。これは有価金属中の炭素の一部が除去されたこと及び廃ニッケル−水素二次電池中の酸化されたニッケル、コバルト、マンガンなどの酸素が還元され、又正極の水酸化ニッケルも脱水分解して酸化ニッケルとなった後、更に水素によって金属まで還元されたことを示している。炭素の減少量は他の条件が同じであれば温度上昇に伴って増加し（実施例４と５は除く）、又雰囲気が不活性ガス雰囲気から水素ガス雰囲気又は水蒸気雰囲気に変化すると、炭素の減少量が増加した。
回転させずに脱炭素工程を行った場合、炭素は0.04重量％まで減少した。又水素ガス雰囲気中で回転させながら1000℃で処理を行うことにより、炭素を0.01重量％まで減少させることができた。
【００２２】
脱炭素工程の反応の律速段階は分子間衝突であり、処理対象の負極主体回収物を回転又は攪拌することにより、炭素減少が促進されることが分かった。
又実施例４及び５の脱炭素工程を水蒸気雰囲気で行った場合の炭素含有量は0.04〜0.05重量％まで減少した。炭素減少の観点からは十分な結果であり、危険な水素ガスの代わりに水蒸気を使用しても所望の炭素減少が得られた。
しかし実施例４及び５を含め回転を行わない実施例（実施例１〜７）では、酸素含有量が約４重量％までしか減少せず、特に前記実施例４及び５では酸素含有量は原料と同じ６重量％台で、酸素減少が不十分であった。
【００２３】
【表１】

【００２４】
実施例 14
有価物回収工程で得られた正極主体回収物（炭素含有量：0.54重量％及び酸素含有量22.5重量％）３ｇを雰囲気中にアルゴンガスを200cc／分で流しながら400℃で1時間脱炭素処理を行い（脱炭素工程）、更にアルゴン雰囲気中、1400℃で1時間加熱溶融して溶媒金属として回収した。得られた溶融金属中の炭素含有量及び酸素含有量はそれぞれ0.22重量％及び18.0重量％に減少した。この結果を表２に示した。
【００２５】
実施例 15 〜 20
実施例14と同じ組成の正極主体回収物を、表２に示す温度及び加熱時間で、かつ雰囲気ガスを流しながら脱炭素処理を行い、更に実施例14と同様の条件で加熱溶融を行った。処理により得られた溶融金属中の炭素含有量及び酸素含有量を表２に示した。なお水素ガス雰囲気での試験の場合は、脱炭素工程における所定の反応時間終了後、気流ガスをアルゴンガスに置換した後、冷却した。
【００２６】
実施例 21 〜 26
実施例14と同じ組成の負極主体回収物を、表２に示す温度及び加熱時間で、かつ雰囲気ガスを流し更に前記負極主体回収物を回転（攪拌）させながら脱炭素処理を行い、次いで実施例14と同様の条件で加熱溶融を行った。処理により得られた溶融金属中の炭素含有量及び酸素含有量を表２に示した。
【００２７】
実施例 14 〜 26 の考察
実施例14〜26の実験結果から、実施例１〜13の実験結果と同様に、脱炭素工程を行うことにより、全ての実施例で炭素含有量及び酸素含有量が減少したことが分かる。これは有価金属中の炭素の一部が除去されたこと及び廃ニッケル−水素二次電池中の酸化されたニッケル、コバルト、マンガンなどの酸素が還元され、又正極の水酸化ニッケルも脱水分解して酸化ニッケルとなった後、更に水素によって金属まで還元されたことを示している。炭素の減少量は他の条件が同じであれば温度上昇に伴って増加し（実施例25と26は除く）、又雰囲気が不活性ガス雰囲気から水素ガス雰囲気又は水蒸気雰囲気に変化すると、炭素の減少量が増加した。
【００２８】
負極主体回収物の場合と異なり、回転させずに脱炭素工程を行っても、炭素量は0.0１重量％まで減少した。これは当初の炭素含有量が小さいからであると考えられる。
回転による脱炭素効果は一定せず、顕著な効果は現れなかった。
水素ガス雰囲気での脱炭素工程により0.01〜0.02重量％のオーダーまで炭素含有量を減少させることができた。酸素含有量は同じ条件下では温度上昇（実施例17及び18を除く）に伴って増加し、実施例26では0.63重量％まで減少した。
【００２９】
【表２】

【００３０】
実施例 27
有価物回収工程で得られた負極主体回収物と正極主体回収物の混合物（炭素含有量：0.91重量％及び酸素含有量16.2重量％）３ｇを雰囲気中にアルゴンガスを200cc／分で流しながら300℃で1時間脱炭素処理を行い（脱炭素工程）、更にアルゴン雰囲気中、1400℃で1時間加熱溶融して溶媒金属として回収した。得られた溶融金属中の炭素含有量及び酸素含有量はそれぞれ0.88重量％及び11.2重量％に減少した。この結果を表３に示した。
【００３１】
実施例 28 〜 32
実施例27と同じ組成の混合物を、表３に示す温度及び加熱時間で、かつ雰囲気ガスとして水素を200cc／分で流しながら脱炭素処理を行い、気流ガスをアルゴンガスに置換した後、冷却した。更に実施例１と同様の条件で加熱溶融を行った。処理により得られた溶融金属中の炭素含有量及び酸素含有量を表３に示した。
【００３２】
実施例 27 〜 32 の考察
実施例27〜32の実験結果から、脱炭素工程を行うことにより、全ての実施例で炭素含有量及び酸素含有量が減少したことが分かる。特に水素ガス雰囲気下（実施例32）で炭素量が0.0１重量％まで、酸素量が1.1重量％まで減少した。これは有価金属中の炭素の一部が除去されたこと及び廃ニッケル−水素二次電池中の酸化されたニッケル、コバルト、マンガンなどの酸素が還元され、又正極の水酸化ニッケルも脱水分解して酸化ニッケルとなった後、更に水素によって金属まで還元されたことを示している。
更にこれらの結果から、電池廃材からの有価金属の回収では手間を掛けて正極主体回収物と負極主体回収物に分離せずに、それらの混合物を脱炭素工程で処理しても有価物中の炭素量を大きく減少させられることがわかった。
【００３３】
【表３】

【００３４】
【発明の効果】
本発明は、有価金属含有廃材から有価物を回収する工程と、回収した有価物を非酸化性雰囲気で加熱して炭素を除去する脱炭素工程とを含んで成ることを特徴とする有価金属の回収方法（請求項１）である。
比較的高純度の炭素及び酸素を含む回収有価物を脱炭素工程で処理すると、有価金属を酸化することなく、炭素量を低減でき、比較的簡単な工程改良により、高品質の有価金属が回収できる。
【００３５】
脱炭素工程の後に、回収有価金属を加熱溶融して溶融金属とする溶融工程を追加しても良く（請求項２）、これにより廃材中の金属を取扱いが容易な溶融金属として回収できる。
本発明の対象とする廃材は特に限定されないが、廃ニッケル−水素二次電池からの有価金属の回収に好適に使用でき（請求項３）、回収対象が電池である場合は、正極主体回収物、負極主体回収物又は正負極混合物のいずれかの形態で脱炭素工程で処理でき（請求項４）、分離の手間の少ない正負極混合物の場合にも炭素含有量は十分に低減できる。
【００３６】
脱炭素工程における非酸化性雰囲気は、不活性ガス雰囲気、水素ガス雰囲気、水蒸気雰囲気、不活性ガス−水蒸気雰囲気及び不活性ガス−水蒸気−水素ガス雰囲気のいずれかから選択され（請求項５）、特に水素ガス雰囲気で有価物を還元し、又は水蒸気雰囲気で有価物を変性させて炭素含有量低減を図ることが望ましい。
脱炭素工程における加熱は、350〜1050℃で５分〜10時間行えば十分であり（請求項６）、該加熱を、有価金属を攪拌しながら行うと（請求項７）、原子又は分子間の衝突が促進されて処理効率が上昇する。
【図面の簡単な説明】
【図１】本発明方法を廃ニッケル−水素二次電池からの有価金属回収に適用した実施態様を示すフローチャート。[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for recovering valuable metals from valuable metal-containing waste materials with high purity in a simple and inexpensive manner, and more particularly, a method for recovering valuable metals such as nickel, cobalt and rare earth metals from waste nickel-hydrogen secondary batteries. About.
[0002]
[Prior art]
As a method for recovering valuable metals such as nickel, cobalt, and rare earth metals from the waste nickel-hydrogen secondary battery, the waste nickel-hydrogen secondary battery is crushed, crushed, sieved, and coarse particles (plastic, iron, After separating impurities into sulfuric acid containing alkali metal and removing impurities from the cobalt-containing nickel solution, electrolysis is performed. A method for recovering metallic nickel and nickel-cobalt alloy by treatment has been proposed (Japanese Patent Laid-Open No. 9-82371). However, this method has a problem that the process of recovering valuable metals such as nickel is extremely complicated.
[0003]
In recovering valuable metals from waste materials containing valuable metals, it is necessary to consider reducing the carbon content in the recovered valuable metals, in addition to simply increasing the recovery efficiency and not complicating the recovery process described above. This has the advantage that the use of recovered valuable metals is widened. Low carbonization may be performed after recovery, but the addition of a process is not desirable in terms of time and cost.
Therefore, for example, in Japanese Patent Application Laid-Open No. 2000-67935, waste nickel-hydrogen secondary batteries are crushed, crushed and sieved, and a valuable material separation process for recovering valuable materials, and an oxidation in which the valuable materials are heated in an oxidizing atmosphere. Disclosed is a method for recovering valuable materials from a waste nickel-hydrogen secondary battery comprising a treatment step and a reduction-melting step patent which is heated and melted in a reducing atmosphere to form a molten metal, and the contained carbon is oxidized in the oxidation treatment step Attempts have been made to remove it.
[0004]
[Problems to be solved by the invention]
In this method, the carbon content in the valuable material is certainly reduced in the oxidation process performed at a high temperature, but at the same time, valuable metals such as nickel, cobalt and rare earth metals are oxidized. It is hard to say that it is a collection method.
As described above, in the conventional method for recovering valuable metals, carbon contained in valuable metal-containing waste materials such as waste nickel-hydrogen secondary batteries remains in the valuable metals after recovery, and the amount of residual carbon is reduced. There is a drawback that the valuable metal is oxidized and the desired valuable metal cannot be obtained.
An object of the present invention is to provide a method capable of recovering valuable metals having a reduced carbon content without substantially oxidizing valuable metals without overcoming such drawbacks of the prior art.
[0005]
[Means for Solving the Problems]
The method of the present invention comprises a step of recovering valuable materials from waste materials containing valuable metals and a decarbonization step of removing the carbon by heating the recovered valuable materials in a non-oxidizing atmosphere. In this recovery method, after the decarbonization step, a melting step of heating and melting the decarbonized valuable metal to form a molten metal may be added.
[0006]
The present invention will be described in detail below.
The method of the present invention is characterized in that a valuable material recovered from a valuable metal-containing waste material is heated in a non-oxidizing atmosphere to remove carbon without substantially oxidizing the valuable metal in the valuable material. In the present invention, the valuable material means a composition containing a valuable metal to be recovered, and in some cases may mean a recovered valuable metal.
In addition to the waste nickel-hydrogen secondary battery, there are waste nickel-cadmium battery, waste lithium ion battery and the like as valuable metal-containing waste materials to be subjected to the method of the present invention.
[0007]
Next, an example in which the method of the present invention is applied to battery waste materials such as a waste nickel-hydrogen secondary battery will be described with reference to the drawings.
FIG. 1 is a flowchart showing an embodiment in which the method of the present invention is applied to recovery of valuable metals from a waste nickel-hydrogen secondary battery.
The valuable material recovery step, which is the first stage of the method of the present invention, may be carried out in the same manner as in the conventional method. Crushed using a pulverizer, pulverized by a wet method using a pulverizer, and classified with a sieve or the like. The non-classified material remaining on the sieve is magnetically sorted to remove non-magnetized materials such as plastic and paper, and then a small amount of plastic and paper are burned and removed.
[0008]
In addition to this, for example, when foamed nickel is used for the electrode plate of the battery, the electrode plate may be subjected to hydrogen reduction as it is or heat-treated in an inert gas atmosphere to recover valuable materials.
When the valuable metal-containing waste material is a waste nickel-hydrogen secondary battery, the valuable material obtained in this manner mainly includes a positive electrode main body recovery material such as nickel and a negative electrode main body recovery material such as a hydrogen storage alloy. A binder and a predetermined amount of carbon are included.
Then, these physically separated valuables are heat-treated in a non-oxidizing atmosphere to oxidize the carbon contained in the valuables and remove at least a part thereof (decarbonization step).
[0009]
The non-oxidizing atmosphere means an atmosphere in which carbon can be removed by reduction or the like without substantially oxidizing metal or alloy by heating, and an inert gas atmosphere, a hydrogen gas atmosphere, a water vapor atmosphere, or an inert gas-water vapor. It is selected from an atmosphere and an inert gas-water vapor-hydrogen gas atmosphere. The inert gas includes argon, nitrogen, helium and the like, and the non-oxidizing atmosphere is particularly preferably a hydrogen gas atmosphere which is a reducing atmosphere.
The heating conditions in the decarbonizing step are preferably 350 to 1050 ° C. for 5 minutes to 10 hours, more preferably 400 to 750 ° C. for 30 minutes to 5 hours. When the heating temperature is less than 350 ° C., condensation dehydration decomposition of a metal compound such as nickel hydroxide contained in the valuable material does not occur,
In addition, the reaction rate is slow and the recovery rate is low. Further, even if the heating temperature exceeds 1050 ° C., the processing efficiency is not remarkably improved, and the energy efficiency of metal recovery is lowered.
[0010]
By heat treatment under an inert gas atmosphere, oxygen, hydrogen and water vapor contained in the recovered valuables contribute to the removal of at least a part of carbon reductively or oxidatively, and at the same time, one of the deteriorated metal oxides. Part is reduced to metal.
In the hydrogen gas atmosphere, at least a part of carbon in the valuable material is reduced by hydrogen, converted into lower hydrocarbons, etc., and removed from the valuable material.
Further, in the steam atmosphere, at least a part of carbon in the valuable material is denatured by the water vapor or is reduced by the water vapor and removed from the valuable material.
[0011]
The valuable material from which at least a part of carbon in the valuable material has been removed in the decarbonization process in this way is converted into a valuable metal, which can be cooled and recovered as a solid metal by stopping heating in the decarbonization process. .
Depending on the application, it may be desirable to recover the molten metal. In that case, the recovered valuable metal may be heated and recovered as a molten metal following the heating in the decarbonization process or once the heating is stopped. (Melting process).
In order to suppress the heating atmosphere and valuable metal oxidation in the melting step, an inert gas atmosphere such as in argon is preferable.
[0012]
In the method of the present invention comprising such a configuration, when the decarbonization step is performed in an inert gas atmosphere, hydrogen and oxygen contained in valuable metal-containing waste materials are effectively used, and a metal that is easily oxidized, such as misch metal. At least a part of carbon contained in the waste material can be removed without substantially oxidizing the material.
Further, when the decarbonization step is performed in a hydrogen gas atmosphere, hydrogen in the atmosphere reductively removes carbon contained in the valuable metal-containing waste material, without substantially oxidizing a metal that is easily oxidized such as misch metal, At least a part of carbon contained in the waste material can be removed.
[0013]
In addition, when the decarbonization step is performed in a steam atmosphere, carbon contained in the valuable metal-containing waste material is removed by reduction or modification, and the oxidizable metal such as misch metal is contained in the waste material without being substantially oxidized. At least some of the carbon that is removed. By carrying out the decarbonization process in this way, carbon in the valuables is 1000 ppm (0.1 wt%) or less at a relatively low temperature without substantial oxidation reaction, and 100 ppm (0.01 wt%) or less depending on the conditions. Can be reduced.
[0014]
Carbon can be easily removed by oxidizing the recovered valuables as before,
Other metal components such as nickel, comments or misch metal are oxidized, and there is a problem that enormous energy is required to reduce the metal oxide and the efficiency is low.
On the other hand, according to the method of the present invention, by adopting the decarbonization step, carbon in the valuable material can be removed without accompanying oxidation of the metal component, and the step of re-reducing the obtained valuable metal-containing waste material. Therefore, valuable metals can be easily recovered from valuable metal-containing waste materials.
In actual operation, slag from waste materials is usually contained in the recovered valuable metal and is obtained as a mixture of valuable metal and slag. When flux is added to this mixture and heated, the molten metal has a high specific gravity and the molten has a low specific gravity. Since it is separated into slag, valuable metals with high purity can be recovered relatively easily.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Although the Example of the collection | recovery method of the valuable metal concerning this invention is described, this invention is not limited to this embodiment.
[0016]
【Example】
Next, the method of the present invention will be described more specifically based on examples.
(Value collection process)
The waste nickel-hydrogen battery was subjected to dry crushing using a shear crusher (Rotoplex Cutting Mill manufactured by Alpine AG, Germany). Next, using a pulverizer (Attriction Machine), pulverization was performed by a wet method, and plastic, paper, and the like were removed by washing with water, and then classified with a sieve (28 mesh). This classified product was a recovered material mainly composed of the negative electrode in which the hydrogen storage alloy of the negative electrode was concentrated. The non-classified material on the sieve was magnetically sorted at 2000 to 3000 gauss to remove the negative electrode Fe substrate. The mixture mainly composed of the positive electrode from which the Fe substrate has been removed is pulverized using a vibration mill (“T-100 type” manufactured by Kawasaki Heavy Industries, Ltd.) and classified by a sieve (24 mesh), whereby the foamed Ni of the substrate and the positive electrode active material A positive electrode main body recovered mainly of nickel hydroxide was obtained.
[0017]
On the other hand, valuables such as nickel-hydrogen and nickel hydroxide, which are battery active materials, were also concentrated in the classified material under the 28 mesh sieve obtained by wet crushing and classification with a crusher. The valuables thus obtained were roughly classified into a negative electrode main body recovered material and a positive electrode main body recovered material, and both were further mixed to prepare a positive and negative electrode mixture.
Subsequently, the decarbonization step and melting of each of the negative electrode main body recovered (Examples 1 to 13), the positive electrode main body recovered (Examples 14 to 26) and the positive and negative electrode mixture (Examples 27 to 32) thus obtained. The process was performed and the amount of carbon and the amount of oxygen in the obtained valuable metal were measured.
[0018]
Example 1
Decarbonization treatment for 1 hour at 400 ° C while flowing argon gas at 200cc / min in an atmosphere of 3g of negative electrode-mainly recovered material (carbon content: 1.27% by weight and oxygen content 6.5% by weight) obtained in the valuable material recovery process (Decarbonization step), and further heated and melted at 1400 ° C. for 1 hour in an argon atmosphere, and recovered as a solvent metal. The carbon content and oxygen content in the resulting molten metal were reduced to 0.93% and 6.5% by weight, respectively. The results are shown in Table 1.
[0019]
Examples 2-7
The negative electrode main body recovered material having the same composition as that of Example 1 was subjected to decarbonization treatment at the temperature and heating time shown in Table 1 while flowing an atmospheric gas, and further heated and melted under the same conditions as in Example 1. Table 1 shows the carbon content and oxygen content in the molten metal obtained by the treatment. In the case of a test in a hydrogen gas atmosphere, after the predetermined reaction time in the decarbonization step was completed, the air flow gas was replaced with argon gas, and then cooled. Ar (H ₂ O) in the table represents argon gas saturated with water vapor.
[0020]
Example 8-13
The negative electrode main body recovered material having the same composition as that of Example 1 was subjected to decarbonization treatment at the temperature and heating time shown in Table 1 while flowing an atmospheric gas and rotating (stirring) the negative electrode main body recovered material. Heat melting was performed under the same conditions as in 1. Table 1 shows the carbon content and oxygen content in the molten metal obtained by the treatment.
[0021]
Consideration of Examples 1 to 13 From the experimental results of Examples 1 to 13 , it can be seen that the carbon content and the oxygen content were reduced in all Examples by performing the decarbonization step. This is because some of the carbon in the valuable metal has been removed, and oxygen such as oxidized nickel, cobalt and manganese in the waste nickel-hydrogen secondary battery has been reduced, and the nickel hydroxide in the positive electrode has also been dehydrated and decomposed. After the nickel oxide was formed, it was further reduced to metal by hydrogen. If the other conditions are the same, the decrease in carbon increases with increasing temperature (except for Examples 4 and 5), and when the atmosphere changes from an inert gas atmosphere to a hydrogen gas atmosphere or a water vapor atmosphere, Decrease amount increased.
When the decarbonization process was performed without rotation, the carbon decreased to 0.04% by weight. Moreover, carbon was able to be reduced to 0.01 weight% by processing at 1000 degreeC, rotating in hydrogen gas atmosphere.
[0022]
It was found that the rate-determining step of the reaction in the decarbonization process is intermolecular collision, and carbon reduction is promoted by rotating or stirring the negative electrode main recovery material to be treated.
In addition, the carbon content when the decarbonization step of Examples 4 and 5 was performed in a steam atmosphere was reduced to 0.04 to 0.05% by weight. From the viewpoint of carbon reduction, the result is satisfactory, and the desired carbon reduction was obtained even when water vapor was used instead of dangerous hydrogen gas.
However, in Examples (Examples 1 to 7) that do not rotate, including Examples 4 and 5, the oxygen content is reduced only to about 4% by weight. In particular, in Examples 4 and 5, the oxygen content is the raw material. The oxygen reduction was insufficient at the same 6 wt% level.
[0023]
[Table 1]

[0024]
Example 14
Decarbonization treatment for 1 hour at 400 ° C while flowing argon gas at 200cc / min in an atmosphere of 3g of positively recovered material (carbon content: 0.54% by weight and oxygen content 22.5% by weight) obtained in the valuable material recovery process (Decarbonization step), and further heated and melted at 1400 ° C. for 1 hour in an argon atmosphere, and recovered as a solvent metal. The carbon content and oxygen content in the resulting molten metal were reduced to 0.22 wt% and 18.0 wt%, respectively. The results are shown in Table 2.
[0025]
Examples 15-20
The positive electrode main body recovered material having the same composition as in Example 14 was subjected to decarbonization treatment at the temperature and heating time shown in Table 2 while flowing atmospheric gas, and further heated and melted under the same conditions as in Example 14. Table 2 shows the carbon content and oxygen content in the molten metal obtained by the treatment. In the case of a test in a hydrogen gas atmosphere, after the predetermined reaction time in the decarbonization step was completed, the air flow gas was replaced with argon gas, and then cooled.
[0026]
Examples 21 to 26
The negative electrode main body recovered material having the same composition as that of Example 14 was subjected to decarbonization treatment at the temperature and heating time shown in Table 2 while flowing the atmospheric gas and rotating (stirring) the negative electrode main body recovered material. Heat melting was performed under the same conditions as in 14. Table 2 shows the carbon content and oxygen content in the molten metal obtained by the treatment.
[0027]
Consideration of Examples 14 to 26 From the experimental results of Examples 14 to 26 , similarly to the experimental results of Examples 1 to 13, the carbon content and It can be seen that the oxygen content has decreased. This is because some of the carbon in the valuable metal has been removed, and oxygen such as oxidized nickel, cobalt and manganese in the waste nickel-hydrogen secondary battery has been reduced, and the nickel hydroxide in the positive electrode has also been dehydrated and decomposed. After the nickel oxide was formed, it was further reduced to metal by hydrogen. If the other conditions are the same, the decrease in carbon increases with increasing temperature (except for Examples 25 and 26), and when the atmosphere changes from an inert gas atmosphere to a hydrogen gas atmosphere or a water vapor atmosphere, Decrease amount increased.
[0028]
Unlike the case of the negative electrode main collection, the carbon content decreased to 0.01% by weight even when the decarbonization process was performed without rotating. This is probably because the initial carbon content is small.
The decarbonization effect due to rotation was not constant, and no significant effect appeared.
The carbon content could be reduced to the order of 0.01 to 0.02 wt% by the decarbonization process in a hydrogen gas atmosphere. The oxygen content increased with increasing temperature (except for Examples 17 and 18) under the same conditions, and decreased to 0.63% by weight in Example 26.
[0029]
[Table 2]

[0030]
Example 27
300 g of 3 g of the mixture of the negative electrode main recovery material and the positive electrode main recovery material obtained in the valuable material recovery process (carbon content: 0.91 wt% and oxygen content 16.2 wt%) in an atmosphere at a flow rate of 200 cc / min. Decarbonization treatment was carried out at 1 ° C. for 1 hour (decarbonization step), and further heated and melted at 1400 ° C. for 1 hour in an argon atmosphere to recover as a solvent metal. The carbon content and oxygen content in the resulting molten metal were reduced to 0.88 wt% and 11.2 wt%, respectively. The results are shown in Table 3.
[0031]
Examples 28 to 32
The mixture having the same composition as in Example 27 was decarbonized while flowing hydrogen at 200 cc / min as the atmospheric gas at the temperature and heating time shown in Table 3, and the airflow gas was replaced with argon gas, followed by cooling. . Furthermore, heating and melting were performed under the same conditions as in Example 1. Table 3 shows the carbon content and oxygen content in the molten metal obtained by the treatment.
[0032]
Consideration of Examples 27 to 32 From the experimental results of Examples 27 to 32 , it can be seen that the carbon content and the oxygen content were reduced in all Examples by performing the decarbonization step. Particularly in a hydrogen gas atmosphere (Example 32), the carbon content decreased to 0.01% by weight and the oxygen content decreased to 1.1% by weight. This is because some of the carbon in the valuable metal has been removed, and oxygen such as oxidized nickel, cobalt and manganese in the waste nickel-hydrogen secondary battery has been reduced, and the nickel hydroxide in the positive electrode has also been dehydrated and decomposed. After the nickel oxide was formed, it was further reduced to metal by hydrogen.
Furthermore, from these results, recovery of valuable metals from battery waste materials does not take time and effort to separate the positive and negative electrode main recovery materials, and even if the mixture is treated in the decarbonization process, It was found that the amount of carbon can be greatly reduced.
[0033]
[Table 3]

[0034]
【The invention's effect】
The present invention comprises a process for recovering valuable resources from valuable metal-containing waste materials, and a decarbonizing step for removing the carbon by heating the recovered valuable resources in a non-oxidizing atmosphere. This is a recovery method (claim 1).
When recovering valuable materials containing relatively high purity carbon and oxygen in the decarbonization process, the amount of carbon can be reduced without oxidizing the valuable metals, and high-quality valuable metals can be recovered through relatively simple process improvements. it can.
[0035]
After the decarbonization step, a melting step of melting the recovered valuable metal by heating to form a molten metal may be added (Claim 2), whereby the metal in the waste material can be recovered as a molten metal that is easy to handle.
Although the waste material which is the subject of the present invention is not particularly limited, it can be suitably used for recovering valuable metals from waste nickel-hydrogen secondary batteries (Claim 3). In addition, it can be processed in the decarbonization step in any form of a negative electrode main body recovery product or a positive and negative electrode mixture (Claim 4), and the carbon content can be sufficiently reduced even in the case of a positive and negative electrode mixture that requires less separation.
[0036]
The non-oxidizing atmosphere in the decarbonizing step is selected from any one of an inert gas atmosphere, a hydrogen gas atmosphere, a water vapor atmosphere, an inert gas-water vapor atmosphere, and an inert gas-water vapor-hydrogen gas atmosphere (Claim 5). In particular, it is desirable to reduce the carbon content by reducing valuables in a hydrogen gas atmosphere or modifying the valuables in a steam atmosphere.
It is sufficient that the heating in the decarbonization step is performed at 350 to 1050 ° C. for 5 minutes to 10 hours (Claim 6). When the heating is performed while stirring the valuable metal (Claim 7), atoms or molecules are interspersed. The collision is promoted and the processing efficiency is increased.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an embodiment in which the method of the present invention is applied to recovery of valuable metals from a waste nickel-hydrogen secondary battery.

Claims

A step of recovering a valuable material that is any of a positive electrode main body recovery material, a negative electrode main body recovery material, or a positive and negative electrode mixture from a waste nickel-hydrogen secondary battery , and the recovered valuable material in a hydrogen gas atmosphere at 350 to 1050 ° C. And a decarbonization step of removing carbon by heating for 10 minutes to 10 hours.

A step of recovering a valuable material that is any of a positive electrode main body recovery material, a negative electrode main body recovery material, or a positive and negative electrode mixture from a waste nickel-hydrogen secondary battery , and the recovered valuable material in a hydrogen gas atmosphere at 350 to 1050 ° C. A method for recovering a valuable metal, comprising: a decarbonizing step for removing carbon by heating for 10 minutes to 10 minutes; and a melting step for heating and melting the decarbonized valuable metal to form a molten metal.

The method for recovering a valuable metal according to claim 1 or 2, wherein the heating in the decarbonizing step is performed while stirring the valuable material.