Concentration and Fractionation of Rare Earth Elements in Soils Surrounding Rare Earth Ore Area

Abstract

BACKGROUND The study on content and fractionation characteristics of rare earth elements (REE) in soils around different types of rare earth mining areas can provide theoretical support and scientific advice for the control of the polluted environment around the rare earth mining areas. OBJECTIVES To reveal the concentration and fractionation characteristics of REE in the soils around different types of rare earth mining areas. METHODS The content and fractionation of 15 rare earth elements in 6 soil samples from the Bayan Obo rare earth tailings area in Inner Mongolia and the Gannan rare earth mining area in Jiangxi Province were determined by the method of Community Bureau of Reference (BCR) sequential extraction and Inductively Coupled Plasma-Mass Spectrometry. RESULTS ∑REE in the soil around the mining area were 264-15955μg/g, significantly higher than the background value (186μg/g) of soils in China. LREE were enriched in the surrounding soils of the Bayan Obo mining area, and REE mainly existed in residual fraction, accounting for 64.0%-89.4% of the total content. HREE were enriched in the soils of the Gannan mining area, the main forms of REE in this area are acid-soluble fraction and reducible fraction, accounting for more than 70% of the total content. REE in the Gannan area were readily transferable and polluted the surrounding environment. CONCLUSIONS The fractionation characteristics of rare earth elements in soils are strongly correlated with pH value. With the decrease of soil pH value, the content of acid extraction fraction of rare earth elements is increasing and the content of residual fraction is decreasing.

Keywords

• soil
• ree
• fractionation analysis
• sequential extraction procedure