A study of the rare-earth chelate stability constants of some aminopolyacetic acids

Mackey, J. L.

doi:10.31274/rtd-180813-498

Cited by 1 publication

(1 citation statement)

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“…Lanthanide recovery from ion-adsorption ores is generally performed either as batch, in-situ, or heap leaching, following similar concepts of toxic metals removal during soil remediation procedures. Although the preferential chelation of lanthanides with various specific ligands is a well-known chemistry fact, the applications were initially limited to laboratory-scale techniques ( [37][38][39][40][41]). Various applications of chelating agents to REE extraction, especially from ion-adsorption clays, have been developed lately.…”

Section: Introduction 1backgroundmentioning

confidence: 99%

Chelation-Assisted Ion-Exchange Leaching of Rare Earths from Clay Minerals

Moldoveanu

Papangelakis

2021

Metals

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The effect of biodegradable chelating agents on the recovery of rare earth elements (REE) from clay minerals via ion-exchange leaching was investigated, with the aim of proposing a cost-effective, enhanced procedure that is environmentally benign and allows high REE recovery while reducing/eliminating ammonium sulfate usage. A processing route employing a lixiviant system consisting of simulated sea water (equivalent to about 0.5 mol/L NaCl) in conjunction with chelating agents was also explored, in order to offer a process alternative for situations with restricted access to fresh water (either due to remote location or to lower the operating costs). Screening criteria for the selection of chelating agents were established and experiments were conducted to assess the efficiency of selected reagents in terms of REE recovery. The results were compared to extraction levels obtained during conventional ion-exchange leaching procedures with ammonium sulfate and simulated sea water only. It was found that stoichiometric addition of N,N′-ethylenediaminedisuccinic acid (EDDS) and nitrilotriacetic acid-trisodium form (NTA-Na3) resulted in 10–20% increased REE extraction when compared to lixiviant only, while achieving moderate Al co-desorption and maintaining neutral pH values in the final solution.

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