海水からの実用的リチウム回収技術の展望

抄録

The demand for lithium has been increasing in recent years, due to its wide application as a raw material for large-capacity rechargeable batteries, light aircraft alloys, and nuclear fusion fuel. Seawater, which contains 230 billion tons of lithium intotal, has thus recently been paid attention as a new resource of this element. However, the recovery of lithium from seawater is quite difficult, since the lithium concentration in seawater is quite dilute, while the co-exiting sodium concentration is quite high. In the present work, novel spinel type manganese dioxide (λ-MnO₂) adsorbents have been developed as the adsorbents for lithium recovery from seawater. The granulated adsorbent of ca. 1-2 mm of particle sizes with high surface density can be conducted by using chitin binder and SiO₂ binder.
From the practical experiments with a pilot plant of lithium recovery in IOES, the concentration of lithium ion in elutant solution is 11,000 times compared with that in seawater, in the case of 150 days operation. We elucidate that the chromatographic operation using the developed absorbent could be applied to large scale lithium recovery system from seawater.