THE AFFINITY OF RARE EARTH ELEMENTS IN HUADIAN AND LUOZIGOU OIL SHALES OF CHINA

Rare earth elements (REEs) are important geochemical indicators and they can provide a lot of useful pertinent information. The inorganic/organic affinity of REEs in Huadian and Luozigou oil shales from Jilin Province, China, was determined using the float-sink and acid-washing tests and sequential chemical extraction methods. The constituents of REEs were determined employing inductively coupled plasma-mass spectrometry (ICP-MS). The results of the float-sink test indicated that the concentration of REEs increased with increasing specific gravity, while during the acid-washing tests, REEs were removed from oil shale. The linear regression of REEs and ash content revealed that the majority of the elements were associated with minerals in coal. In addition, acid washing proved to influence the desorption of REEs. REEs in oil shale exist mainly in the mineral fraction, while the organic fraction plays a major role in their aggregation, especially in case of light rare earth elements (LREEs). REEs in oil shale derived from terrigenous clastic rocks when they were absorbed by organic matter or minerals.