Determination of Coal Quality and Depositional Environment Based on Ash Content, Total Moisture, and Total Sulphur on Gross Calorific Value of Coal in the Batuah Village, Loa Janan District, Kutai Kartanegara Regency, East Kalimantan Province

Abstract

Coal is formed from the accumulation of plant material that undergoes decomposition, compaction, and deposition over millions of years due to physical and chemical influences. This study was conducted in the Kampung Baru Formation, Kutai Basin, to determine quality and depositional environment of coal. Data were obtained from three boreholes (DH-01, DH-02, and DH-03) with having coal thicknesses of 17.8 m, 9.8 m, and 4.8 m, respectively. The analyses performed proximate and ultimate. The results showed that huminite (densinite) was the dominant maceral component with an average of 36.6%, followed by liptinit (cutinite) at 6.8% and inertinite (semifusinite) at 3.03%. The mineral matter content was dominated by pyrite (1.8–6.8%) and clay (0.8–7.6%). The average values of the proximate and ultimate analyses show an ash content of 20.60%, total water of 12.25%, total sulphur of 0.66%, and a calorific value of 4,042.3 cal/g. Based on the United Nations (1998) and ASTM classifications, coal in the study area is categorized as a lignite B to low-medium rank coal. Depositional environment analysis is based on Lamberson diagram classification (1991), which shows that the coal was deposited in a limno-telmatic zone with a lower to upper delta plain facies.

Keywords: Coal, Kutai Basin, Kampung Baru Formation, Quality, Depositional Environment, Maceral