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Rare Earth Elements and Yttrium (REY) are Critical Raw Materials (CRM) which are essential for modern technologies. They are conventionally mined from igneous rocks, and they are now a priority exploration target worldwide. The ultimate objective of the proposal is the extraction of REY from the treatment of Acid Mine Water (AMD). This is an unwanted pollution that is expected to flow out from coal and sulphide mines for hundreds of years. AMD hosts REY concentrations much higher than those in continental waters and oceans. AMD treatment systems produce low crystalinity iron and aluminium hydroxides. Preliminary surveys have shown that these solids retain practically all REY dissolved in AMD. Therefore, the outputs may provide a new and almost inexhaustible natural source of REY that is sustainable and beneficial to the environment. The objective of the proposal is to test the feasibility and the optimum conditions to recover REY from AMD. Two methods of AMD neutralisation and precipitation of REY are proposed: the addition of controlled doses of alkaline reactives for high flow rate discharges; and the passive infiltration through a limestone filter. Both procedures aim to obtain a sequence of precipitates where REY can be obtained selectively. The systems will be tested at laboratory and field scale in the Spain and in South Africa. These hydrated precipitates are then dried and concentrated into oxides ready to be transported for extraction. Finally, REY concentrate with high purity will be obtained by a multi-step extraction process consisting of leaching and chemical separation. From these solutions, advanced REY materials could be obtained (coordination polymers, self-assembled lanthanide-organic frameworks) showing interesting application (catalyst, photonic or magnetic properties). Also a novel method based on a recently developed recyclable porous material, called CH Collector, will be tested to directly collect REY from AMD without any precipitation step.

AMDREY: extracting REE from Acid Mine Drainage”
Entidad financiadora: ERAMIN-PCIN-2015-256
Entidades participantes: CSIC
Duración: 2016-2017
Investigador principal: C. Ayora (Coordinador)
Número de participantes:3
Project staff: C. Ayora, E. Torres, A. Lozano, J. Bellés, R. Bartrolí, M. Cabañas

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