Fractionation patterns and influence mechanism of rare earth elements in acid mine drainage

The NASC-normalized patterns of the rare earth elements(REE) and their main influence factors in acid mine drainage(AMD) from two coal mines of Shanxi province,North China,were investigated by determining the concentrations of REEs in the AMD,sediments,country rocks and coal samples,as well as further analyzing through adsorption and desorption experiment and hydrogeochemistry software PHREEQC.The results show that: 1) AMD has high REE concentrations and its NASC-normalized patterns are typically convex;2) bedrock and pyrity were the main sources of REE in AMD,the REE abundance of coals were very low;3) pH is the most important factor influencing the concentration and NASC-normalized patterns of REE in AMD;4) with the increasing of pH,hydroxide Mn has more influence on REE concentrations,and bearing-iron sediments in AMD preferentially to remove heavy REEs and middle REEs compared with light REEs;5) the REEs speciation modeling indicates sulfate complexe(REE(SO4)+,52.8%-79.4%) is the dominant REEs species,and REE(SO4)-2and REE3+ are the secondary REEs species in the AMD.