Combined Mining and Pulp-Lifting of Ferromanganese Nodules and Rare-Earth Element-Rich Mud around Minamitorishima Island in the Western North Pacific: A Prefeasibility Study

Abstract

An examination of the technical and economic feasibility of the combined mining of the rare-earth element-rich mud (REE-rich mud) and ferromanganese nodules (FN) around Minamitorishima (Marcus) Island in Northwest Pacific is introduced. A previous study showed that the mining of REE-rich mud around Minamitorishima Island was not economically feasible. Therefore, in this study, three changes from the previous mining model to improve its economy are proposed. The first one is combined mining with FN in the area. The second one is introducing a pulp-lifting system that can lift both REE-rich mud and FN at high concentrations through a riser pipe. The third one is the reuse of waste mud and processed slag for construction materials. The economic evaluation results show a change from a slightly negative to quite positive economy depending on the mixing ratio of REE-rich mud and FN in the pulp-lifting. In addition, some technical approaches necessary to realize the combined mining method are introduced.

Effects of Migration and Diffusion of Suspended Sediments on the Seabed Environment during Exploitation of Deep-Sea Polymetallic Nodules

“…In addition, the properties of superficial sediments also vary with depth. The particle size of sediments shallower than 10 cm in the surface layer is smaller, and approximately 90% of the particles are smaller than 0.02 mm [65]. In addition, the water content of surface sediments is extremely high, generally exceeding 100% [66].…”

Comminution of Polymetallic Nodules with a High-Pressure Water Jet

“…Nowadays, cobalt-rich ferromanganese crusts [17], which also contain nickel, molybdenum, and copper [18], are also becoming increasingly important for the development of electronics and battery industries. In addition, such crusts sometimes also contain rare earth elements [19,20]. For example, Fe-Mn crusts found in the Clarion-Clipperton zone contain significantly more metals (Tl-1700 times more, Te-10 times more, as well as Co and Y) than the entire global terrestrial resource base of these metals.…”

Distribution of Rare Earth Elements and Yttrium in Sediments From the Clarion‐Clipperton Fracture Zone, Northeastern Pacific Ocean

“…REY‐enriched sediments are also commonly reported in the Clarion‐Clipperton Fracture Zone (CCFZ), northeastern Pacific Ocean (Figure 1a) (Kato et al., 2011; Menendez et al., 2019; Paul, Volz, et al., 2019; Zawadzki et al., 2020). Of particular note are the high‐REY units (∑REY contents of up to 1,200 ppm) distributed in some places at very shallow depth within a few decimeters beneath the sediment surface covered with polymetallic nodules (Kim et al., 2012; Seo et al., 2014), providing conditions favorable for combined mining of REY‐rich mud and polymetallic nodules (Yamazaki et al., 2021; see Pak et al. [2019] for further discussion on their resource potential).…”