A new and prospective resource for scandium: Evidence from the geochemistry of deep-sea sediment in the western North Pacific Ocean

Scandium is a critical element in state-of-the-art, green technologies. However, it is also extremely expensive due to its scarcity. Recently, some deep-sea sediments that contain significant amounts of rare-earth elements that are indispensable to modem industries have been discovered in the western North Pacific Ocean, and the concentration of Sc in these sediments is comparable with that of land-based mines. A simple leaching experiment has demonstrated that up to 70% of Sc in these sediments, contained within biogenic calcium phosphate particles, can be recovered in 5 min, using dilute acids. On the basis of available core samples, we propose that a promising target area to mine Sc is along a west east transect between longitudes 153 degrees 30'E and 154 degrees 00'E, at an approximate latitude of 21 degrees 58'N. Depending on the depth of the most enriched sediment layer, just 1 km(2) of the sediment could potentially yield 3.3-6.6 times the current global annual consumption of Sc. Because these sediments contain an unusually high concentration, at commercial quantities, of industrially important, heavy rare-earth elements, apart from Sc, they could be a productive source for the long-term extraction of these critical metals.