The Relationship between Indonesian Coal Qualities and Their Geologic Histories

Indonesia is a country that has many coal deposits, especially in Sumatra Island and Kalimantan Island. In both Islands have many coal formations. 8 samples in this study are from three formations, they were Warukin Formation in East Kalimantan, Pengasih Formation in Jambi, and Muara Enim Formation in South Sumatra. The main factor to determine coal qualities is the coal rank. The coal rank from the lowest to the highest are lignite, sub-bituminous, bituminous, and anthracite. The factors that influencing of coal ranks are calorific value, volatile matter, moisture (inherent water), and fixed carbon. One of the influencing factors is geologic history. Geologic history is the key to understanding the story of rocks in the past. The purpose of this study is to review the relationship between coal samples qualities and their geologic histories. The differences in coal ranks of those samples have difference geologic histories. Those factors that influencing of coal ranks are rocks age, depositional environment, temperature, pressure, and recent geologic events.