Recovery of Rare Earth Elements from Acid Mine Drainage Using Staged Chemical Precipitation
Acid mine drainage(AMD)is of great interest because of its high concentration of dissolved rare earth elements and yttrium(REY),and the recovery of REY from AMD is a potential source of rare earth re-plenishment.To investigate the feasibility of recovering REY from AMD,AMD with REY content of 29.8x10-6 was collected from an abandoned coal mine shaft in Guizhou as raw material in this study,and a graded chemi-cal precipitation-acid dissolution-oxalic acid selective precipitation method was used to recover REY from AMD.experimental results show that using NaOH as pH adjuster after removing 99.8%of Fe3+and 67.1%of Al3+and other major contaminating ions from AMD,a highly enriched precipitate(about 1.0%content)of REY was ob-tained.The precipitate was dissolved by HNO3 to obtain a REY-rich preconcent rate,and 95%of the REY in the concentrate was recovered by adding oxalic acid solution at an optimal pH of 2.The final product was cal-cined and oxidized to obtain rare earth oxides with a purity of 97%.