开滦煤洗选过程中稀土元素的迁移和分配特征

On the basis of coal geochemistry and coal petrology, the content, migration, and distribution of rare earth elements (REEs) in the Paleozoic coals and their washing products were determined using inductively coupled-plasma mass spectrometry (ICP-MS), sequential chemical extraction procedure, and optical microscope. The contents of REEs in 47 coal channel samples from 10 mines of Kailuan Coalfield were determined. The results show that the REEs are not significantly enriched in the coals from the Kailuan Coalfield, North China. The content of REEs increases in the order of cleaned coal (76.63 w/10-6), raw coal (85.84 w/10-6), middling coal (88.6 w/10-6), tailing coal (125.93 w/10-6), and coal slime (177.08 w/10-6). The values of δEu and δCe are similar among raw coal and its washing products. The obvious difference of REEs in raw coal and its products is their different concentrations. Six states of REEs, water soluble, exchangeable, organic, carbonate, silicate, and sulfide states, are classified to study modes of occurrence. Modes of coccurrence of REEs in raw coal and middling coal are similar. REEs in the cleaned coal are mainly associated with organic matrix and silicates. Most of REEs in the tailing coal and coal slime are associated with alumino-silicate mineral matters. However, Tm, Yb and Lu associated with organic matter are surprised high in all coal washing products compared with the other REEs. Tm, Yb, and Lu associated with organic matter in the coal slime are 2.4%, 3.5% and 2.8%, respectively. Combined with the results of sequential chemical extraction and mineral composition analyses, it can be concluded that the dominant influence factors on the concentration and modes of occurrence of REEs are in order of clay minerals, organic matter, pyrite, quartz and calcite.