TITLE:
Enrichment Characteristics, Occurrence and Origin of Valuable Trace Elements in Lignite from Linchang Coal Mine, Guangxi, China
AUTHORS:
De’e Qi, Shihao Wu, Shenyong Li, Gui Zhao, Jingkai Xing, Shuai Kang, Qian Wang, Wenyue Gao
KEYWORDS:
Lignite, Valuable Trace Elements, Enrichment Characteristics, Occurrence Modes, Geochemical Origin
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.12,
December
29,
2021
ABSTRACT: To evaluate the comprehensive exploitation and utilization values of coal
resources in Baise basin of Guangxi, the Paleogene coal of Linchang coal mine
were sampled and studied. The enrichment characteristics, occurrence modes, and
geochemical origin of valuable trace elements in coal were studied by using
X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray
spectrometer (SEM-EDS), polarizing microscope, X-ray fluorescence spectrometry
(XRF), inductively coupled plasma mass spectrometry (ICP-MS) and atomic
fluorescence spectrometry (AFS). The results reveal that Linchang coal is
ultra-low calorific value lignite with high ash, medium sulfur, medium-high
moisture and medium volatilization. The minerals are mainly composed of illite,
kaolinite, quartz, pyrite, siderite, bassanite, anhydrite and
magnesium-containing calcite. Compared with average values for world low-rank
coals, the contents of valuable trace elements in Linchang coal are higher on
the whole, which is characterized by the high enrichment of U, the enrichment of elements Li, V and Ag, and
the slight enrichment of elements Be, Ga and Se. Lithium, V, Ga and Ag
mainly occur in clay minerals including illite and kaolinite, and part of V is
related to organic matter. The carriers of
Be in coal are clay minerals and organic matter. Selenium is mainly
combined with organic matter and a small amount exists in pyrite. Uranium is
primarily organically bound in coal. The enrichment of valuable trace elements
in Linchang coal is influenced by the sedimentary source, coal-forming environment, underground circulating
water and geological structure. The sedimentary environment of the coal seam is
an acid-reduced terrestrial peat swamp, and the source is Triassic sedimentary
rocks weathered from feldspathic volcanic rocks around Baise basin.