Geochemical Characteristic of the Nyalau Formation from Merit-Pila Coal Field, Sarawak, Malaysia: Its Implications on Depositional Condition and Thermal Maturity

Depositional condition and thermal maturity can be derived from conventional
geochemical analyses. Despite of this importance, little publication on the Nyalau
Formation is available using proximate and calorific value analysis. This study is aim to
reveal the geochemical characteristic of the Nyalau Formation from Merit Pila coal
deposits. The investigations are expected (1) to determine the total moisture and ash
content of coal for individual coal seams; (2) to interpret the quality of individual coal
seams in terms of the content of volatile matter and fixed carbon, and (3) to evaluate the
coalification rank of Merit Pila coal deposits with other Tertiary coal deposits in Southeast
Asia. Five different parameters have been carried out on the sample collected in Merit-Pila
coalfield which are calorific value, total moisture, volatile matter, fixed carbon and ash.
The moisture content of the studied coal is determined to be ranging from 7.1 to 19.3 wt.%
with an arithmetic means of 14.4 wt.%. This arithmetic means considered to be low
moisture content which indicates that the coal seams are deposited far below the ground
with thick bed is deposited on top of it. While, the ash yield ranging from lo 0.5 to 59.8
wt.% with arithmetic means of 21.2 wt.%. This ash content value is characterized by high
ash yield which suggesting high amount of inorganic content input during peat deposition.
Moreover, Merit-Pila coal deposits are classified to be thermally immature with the
coalification rank ranging from lignite to sub-bituminous coal. This regional value is
supported by a low fixed carbon contents, high volatile matter contents and low calorific
value limits, and agreement with influence of the arithmetic means of total moisture
content. Besides, this thermal maturity result is substantiated by the other Tertiary coal
deposits in Southeast Asia.