Abstract: Coal and rock samples from magmatic intrusion area of Wolonghu Coal Mine, Huaibei Coalfield, were systematically collected to determine contents of mercury, ash, volatile matter, and moisture and spectated sulfur, as well as to investigate the distribution and modes of occurrence of mercury in intruded coal seams. The results show that (1) the magma intrusion into coal seams resulted in the increase in ash content and the decrease in volatile matter. The main form of sulfur was pyrite sulfur (42.08% ) and inorganic sulfur (52.51%) in coal; (2) mercury in the intruded coal seams was as high as 0.23×10-6, which was 1.4, 1.2 and 1.3 times of that in the Carboniferous-Permian coals from North China, China and the USA; (3) the contents of mercury decreased with the increase in the distances between coal seams and intrusion body, and the distribution of mercury was different for the upper and lower coal seams in contact with the intrusion body; (4) mercury in the coal was mainly in inorganic form, primarily pyrite. Meanwhile, mercury bound with organic sulfur also exists. Magmatic hydrothermalism is identified as the causes accounting for the enrichment and change of forms of mercury, and the variations of coal quality.

Key words: mercury, coal, magmatic intrusion, modes of occurrence