Akita University Team Successfully Extracts Rare Earth from Hot Spring

Akita University Team Successfully Extracts Rare Earth from Hot Spring
Yomiuri Shimbun: 温泉からレアアース採取、秋田大グループが成功
July 22, 2011

Rare earth, an essential component of advanced technology, was successfully extracted from Tamagawa Onsen, a hot spring in Senbei City, Akita Prefecture that is famous for its strongly acidic water, by an Akita University Faculty of Engineering and Resource Science research team led by Professor Atsushi Shibayama (age 40), according to a July 21 announcement.

The group says 520 kilograms of rare earth can be extracted from the spring per year. This is too little to be useful for businesses, but this discovery shows that rare earth can be recovered from hot springs and the ocean floor.

According to the announcement, Dr. Shibayama’s team has collected 200 liters of water from Tamagawa Onsen since last November. After adding nitrium to the water to neutralize it and rare earth to the iron and aluminum molecules inside to cause precipitation, 15 additional milligrams of rare earth per liter of water were extracted. This rare earth was confirmed to include 14 elements, including dysprosium, which is used in the magnets of hybrid automobile engines, and europium.

The group concluded that roughly 750 kg of rare earth flow through Tamagawa Onsen each year, of which 520 kg could be recovered.

Rare earth is problematic because of its unstable supply (roughly 90% of which was thought to be in China until this month) and its rising price. Japan uses about 30,000 metric tons per year.

Dr. Shibayama said in the press conference at Akita University, “Although there is too little rare earth in this spring for it to become the base of a business operation, there’s a high probability rare earth can be found in other springs with highly acidic water, as well. Our method can also be used to recover rare earth from the ocean floor.” He plans to investigate other springs from here on.

Akita University President Noboru Yoshimura said, “Small as the the amount may be, we confirmed that our country has a supply of this resource. We would like to investigate how to make practical use of it and decrease the cost of extraction.”

Original/原稿:
温泉からレアアース採取、秋田大グループが成功

強酸性の名湯として知られる秋田県仙北市の玉川温泉の温泉水から、ハイテク製品に欠かせないレアアース(希土類)を採取することに成功したと、秋田大学工学資源学部の柴山敦教授(40)らの研究グループが21日、発表した。

年間約520キロ・グラムのレアアースが回収可能という。量が少ないため商業利用は難しいが、他の温泉や海底からの採取につながる成果が得られたとしている。

発表によると、柴山教授らが2010年11月、玉川温泉の温泉水200リットルを採取。水酸化ナトリウムを加えて中和状態にし、温泉水に含まれている鉄やアルミニウムにレアアースを付着、沈殿させる方法で、1リットル当たり0・15ミリ・グラムのレアアースを採取した。レアアースは、ハイブリッド自動車のモーターの磁石に使われるジスプロシウムや、ユーロピウムなど計14種類の元素が確認できたという。

また、玉川温泉で湧出している温泉水には、年間約750キロのレアアースが含まれ、このうち約520キロが採取可能とわかった。

レアアースは、中国が生産量の9割を占めており、不安定な供給と、価格の高騰が問題となっている。日本国内の年間消費量は約3万トン。

柴山教授は秋田大で記者会見し、「量が少ないので商業ベースに乗せるのは難しいが、他の強酸性の温泉でも採取できる可能性は高い。海底に眠るレアアースの分離にも技術を転用できる」と話した。今後、他の温泉でも調査するという。

同大の吉村昇学長は「微量とはいえ、国内にレアアースの供給源を確保できる可能性が見えた。実用化に向け、コスト面での調査も行いたい」と話した。

(2011年7月22日08時57分 読売新聞)

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