Resumen de Rare Earth Elements in Acid Mine Drainage
Carlos Ayora Ibáñez, Francisco Macías Suárez, Ester Torres Sánchez, José Miguel Nieto Liñán
Rare Earth Elements and Yttrium (REY) are raw materials of increasing importance for modern technological developments. Most of production is concentrated in China, and finding alternative sources of REY has become a need for the rest of countries. Acid Mine Drainage (AMD) may contain REY in concentration various orders of magnitude higher than the rest of waters. The distribution pattern of AMD is depleted in light (and less expensive) REE with respect to the clay standards. REY does not segregate into Fe(III) precipitates in acidic streams. Mixing with more alkaline streams increases pH above 5, and REY are entirely scavenged from solution with basaluminite. The same behaviour is observed in calcite based passive remediation systems of AMD. There, schwertmannite precipitates do not allocate REY that are completely retained in the basaluminite precipitation front. No change in the distribution pattern is observed in this retention process. Although REY rates in the basaluminite treatment residue are competitive, the annual reserves are far below those targeted by current prospecting. However, AMD is expected to run for hundreds of years and therefore, total reserves are unlimited.
