Abstract

The Tazareh mine in the eastern Alborz coalfield is one of the most important coal-producing areas in Iran and contains medium volatile (19.1–31.5%), low sulfur (0.015–0.491%) and variable ash yield (3–31.5%) bituminous coal. In this research, a total of 21 samples were collected from the Tazareh coal layers, footwall and hanging wall. The concentrations of rare earth elements (REEs) and other elements were determined by inductively coupled-plasma mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). Additionally, traditional features of coal and host rocks were studied by X-ray diffraction (XRD) and petrographic methods. The concentration coefficient (CC) of Tazareh coal samples show that Sc (CC = 2.71), Be (CC = 2.68) and Ni (CC = 2.30) are slightly enriched, Li, Cr, Pb, Sb, V, Cs, As, Co, Cu, Nb, Y, Rb, Tl, REE, Zr, Zn, Ta and Th (0.5 < CC < 2) are normal, and concentrations of remaining trace elements are lower than the average world hard coals. The NASC-normalized REEs pattern and (La/Yb)_n, (La/Sm)_n, (Gd/Yb)_n, and (La/Lu)_n ratios in the Tazareh coal confirm that the LREEs are enriched relative to HREEs, and comparatively, the degree of LREE enrichment of coal is lower than that of coal-bearing shale and argillaceous shale. Coal-bearing strata were deposited under oxic conditions in a warm-humid climate. The average content of REE + Y in Tazareh coal (58 ppm) is lower than world coals (83 ppm), while Sc is enriched.