Development of Simultaneous Recovery System of Rare Metals from Deep Ocean Water

为了从深海水中高效、选择性地分离和回收稀有金属锂、锶、锶和铯，我们开展了以下工作：(1)开发对钠、镁等共存离子具有高选择性的锶、锶、铯和锂的新型吸附剂；(2)评价吸附剂的吸附分离性能；(3)开发适合于防止吸附柱中压降过大的吸附剂的造粒方法；(4)利用柱组件研究海水中稀有金属的同时回收体系。本研究取得了以下成果，并已在多个期刊和国际会议上发表。(1)成功研制出高选择性识别锶、铯离子的A型沸石吸附剂。我们还研究了吸附剂的吸附性能与选择性和晶体结构的关系。(2)我们阐明了离子交换机制下对目标离子的吸附是先于吸附的。(3)我们用甲壳素、氧化铝和二氧化硅等几种粘结剂制备了毫米量级的颗粒状吸附剂。确定了最佳粘结剂和粘结剂用量比。我们还开发了一种利用挤出机进行造粒的新方法。(4)详细考察了一些实验条件对人工深海水中稀有金属选择性回收的影响。考察了在柱组件系统吸附-脱附操作条件下，颗粒吸附剂的耐久性。

For the purpose of efficient and selective separation and recovery of rare metals such as lithium, strontium, rubidium and cesium from deep ocean water, we have carried out : (1) Development of novel adsorbents having high selectivity of strontium, rubidium and cesium lithium against coexisting ions such as sodium, magnesium, (2) Evaluation of adsorption and separation performance of the adsorbents, (3) Development of granulation method suitable for the adsorbents preventing large pressure drop in the adsorption column, and (4) Investigation of simultaneous recovery system of rare metals from the seawater using the column module. As results of this research, the followings were obtained and these results were already published in several journals and international conferences.(1) We have successfully developed zeolite A adsorbent which high-selectively recognizes strontium and cesium ions. We have also investigated the relationship between adsorption properties and selectivity and crystal structures of the adsorbents.(2) We have elucidated that the adsorption of target ions was preceded under the ion exchange mechanism.(3) We have prepared the granular adsorbents with some millimeter order using with several kinds of binders such as chitin, alumina and silica binders. We have elucidates the optimal binder and amount ratio between adsorbent and binder. We have also developed a novel granulation method using extruder.(4) We have examined the influence of some experimental conditions on the selective recovery of rare metals in artificial deep ocean water in detail. We have investigated the durability of the granulated adsorbents under the adsorption-desorption operation of the column module system.