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

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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.