Continental shelves as potential resource of rare earth elements

Abstract

The results of this study allow the reassessment of the rare earth elements (REE) external cycle. Indeed, the river input to the oceans has relatively flat REE patterns without cerium (Ce) anomalies, whereas oceanic REE patterns exhibit strong negative Ce anomalies and heavy REE enrichment. Indeed, the processes at the origin of seawater REE patterns are commonly thought to occur within the ocean masses themselves. However, the results from the present study illustrate that seawater-like REE patterns already occur in the truly dissolved pool of river input. This leads us to favor a partial or complete removal of the colloidal REE pool during estuarine mixing by coagulation, as previously shown for dissolved humic acids and iron. In this latter case, REE fractionation occurs because colloidal and truly dissolved pools have different REE patterns. Thus, the REE patterns of seawater could be the combination of both intra-oceanic and riverine processes. In this study, we show that the Atlantic continental shelves could be considered potential REE traps, suggesting further that shelf sediments could potentially become a resource for REE, similar to metalliferous deep sea sediments.

Rare earth elements sorption to iron oxyhydroxide: Model development and application to groundwater

“…6). In this model, the influences of organic matter and manganese oxyhydroxides on REE speciation were not taken in account, although previously researches demonstrated they could played an important role in REE behavior (Tang and Johannesson, 2003;Nakada et al, 2013;Pourret et al, 2009;Pourret and Tuduri 2017). However, as was the case documented by Verplanck et al 2004and Quinn et al (2007), the generalized proposed model is able to provide important suggestion for REE complexation with iron oxyhydroxides in Fe-rich groundwater-aquifer systems, unless other potential complexers (e.g.…”

“…Results from field experiments under acidic pH (pH<5.0) further indicated that LREE were preferentially enriched by hydrous Fe(Ш) oxides (Verplanck et al, 2004). Even if Mn oxides and humic substance play significant roles (Tang and Johannesson, 2003;Nakada et al, 2013;Pourret and Tuduri, 2017); previously cited studies demonstrated that Fe-oxyhydroxides may also control REE fractionation and partitioning in the natural environment.…”

Rare Earth Elements and Other Critical Metals in Deep Seabed Mineral Deposits: Composition and Implications for Resource Potential

“…Data for ferromanganese crusts are from this study, and KORDI reports [21,22]. Data for deep-sea sediment are compiled from this study and a KORDI report [10]. The metal contents of seafloor massive sulfides are from this study and a KORDI report [23].…”

“…Traditionally, Co, Ni, and Mn have been the target metals in nodules and crusts, with less focus on rare earth metals. The majority of REE studies have focused on the origin and genetic environment of ore deposits (e.g., [9][10][11][12] and references therein). Only a few studies have investigated the potential of classical deep-sea mineral deposits as critical metal sources, despite the discovery of seabed mineral deposits almost 50 years ago [3,4,[13][14][15][16].…”

Bioreductive Dissolution as a Pretreatment for Recalcitrant Rare-Earth Phosphate Minerals Associated with Lateritic Ores

“…The demand for REE is growing at a rate of approximately 5-10% as these metals are increasingly used in modern technology including the metallurgy, fine chemical, automotive, oil, and renewable energies industries, etc. [3,4]. In recent years, there has been an increasing effort to identify additional potential supplies of REE to limit economic risk in the supply chain, given the fact that cuts in China's exports quota in recent years have provoked uncertainty among the hi-tech markets [4].…”