Шивээ-Овоо ордын нүүрсний петрографийн судалгааны үр дүнгээс

Abstract

Shivee-Ovoo coal deposit (open-pit mine) is located in Choir-Nyalga coal-bearing basin in eastern Mongolia. Coal seams are hosted in Lower Cretaceous Khukhteeg Formation. The study aims to determine depositional environments of coal seams of the deposit. In total, twenty-three coal samples were collected from Seams I, II and V of the open pit. The Shivee-Ovoo coals have high moisture (29.8 to 44.8%, ar basis) and high volatile matter content (38.1 to 51.2%, daf basis). Ash content of Seam V ranges from 25.5 to 39.5% (ar basis), whereas that of Seam I and II are low, ranging from 5.1 to 17.5% (ar basis). The calorific values of Seam I, II, and V range from 1833 to 3096 kcal/kg (ar basis). Total sulphur contents of the all three seams are low (0.64 to 0.92%, d basis). The coal of Shivee-Ovoo deposit is classified as KH-3 according to Mongolian standard. The results of coal petrography revealed that the maceral  compositions of Seams I and II are similar, whereas that of Seam V are different. Huminite and mineral matter contents of Seam V are high compared with those of Seams I and II, whereas inertinite content of Seam V is notably low. Liptinite contents of the all three seams are similar. Gelification Index (GI) and Tissue Preservation Index (TPI) suggest the limnic origin with high tree density. The peats of Seams I and II were accumulated in a mire with alternating oxic and anoxic conditions. The peat of Seam V was accumulated under moderate to high flooding condition.