Year

1994

Degree Name

Doctor of Philosophy

Department

Department of Geology

Abstract

Eastern Kalimantan has the second largest coal resources in Indonesia after Bukit Asam and Ombilin Coalfields of Sumatera, but currently has the highest coal production. It is also the area forecast to have the highest growth rate in production to the year 2000.

The Kutei, Barito, Asem Asem and Tarakan Basins developed as a result of rifting in the Makassar Strait during the mid-Tertiary. The basins have cratonic and back-arc (retroarc) settings with similar depositional histories from the Eocene through to the Middle Miocene. Coal was deposited in both Eocene and Miocene sequences in depositional environments ranging from fluviatile to deltaic. Economic coal deposits of Miocene age occur in all basins but economic Eocene coals occur only in the Barito and Asem Asem Basins.

The aim of this study was to evaluate lateral and vertical variations in coal thickness and to study the chemical and physical (including petrographic) properties to provide valuable input for short and long term planning for the utilisation of the coals of this important coal mining district.

Vitrinite and liptinite are the dominant macerals in both Eocene and Miocene coals. Inertinite is a minor component but it is higher in Miocene coals. Typical ratios for vitrinite to liptinite are higher in Miocene coals (8 to 15) than for Eocene coals (5 to 10). Mineral content is low in most of the coals except in some Eocene coals where it is abundant.

Five types of exsudatinite have been recognised in the present study on the basis of morphology and mode of occurrence. Veins of exsudatinite are typically associated with telovitrinite whereas lensoidal exsudatinite is associated with detrovitrinite and resinite. Both liptinite and meta-exsudatinite can be distinguished within coals that have been subjected to contact alteration.

The rank of the Miocene coals ranges from soft brown coal to high volatile bituminous (Rvmax of 0.30% to 0.71%) whereas for Eocene coals it ranges from subbituminous to high volatile bituminous (Rvmax of 0.43% to 0.66%). Thus, unlike most of the Miocene coals, the Eocene coals show only a small range of coal ranks. Miocene coals in Sangatta area have been altered to semi-anthracite by igneous intrusion.

Most of the eastern Kalimantan coals are suitable for feedstocks in combustion and conversion (liquefaction and gasification) processes. Combustion is the most important present day use for coals but suitability of coals for combustion is restricted by the contents of minerals, sulphur, liptinite and inertinite as well as rank.

The Miocene coals from Sangatta, Mahakam and Berau are the best coals for pulverised fuel combustion processes followed by the Tanjung (both Miocene and Eocene) and Pasir (Eocene) coals. Of the coals currently mined, or likely to be mined in eastern Kalimantan, Asem Asem, Satui and Senakin coals are considered to be the least suitable coals for pulverised combustion, because they have high moisture (Asem Asem), liptinite (Satui) and mineral matter (Senakin).

The exceptionally high sulphur in some coals will produce high concentrations of S02 when combusted. Nevertheless, the Satui and Senakin coals are of sufficiently high quality to be used for power generation in Indonesia and the Asem Asem coal could be used to fuel a "mine mouth" power station. The Satui and Senakin coals are only marginally suitable for export under current market conditions.

All Miocene coals and the Eocene coals from Satui are suitable as feedstocks for liquefaction and gasification processes. The economic of the use of eastern Kalimantan coals for both gasification and liquefaction processes is dependent upon using the solid residues produced for subsequent combustion in power generation. However, in order to use the residues for combustion specifically designed char-fired plants will have to be built.

Sangatta, Senakin, Pasir and Tanjung (Eocene) coals are suitable for low-temperature (600°to 700°C) carbonisation to produce chars. Good quality cokes, on the other hand can only be produced from coals with Rvmax in the range from 1.0% to 1.40% and the vitrinite content should be50%. Accordingly, none of the eastern Kalimantan coals can be used as coke oven charges although selected coals such as Sangatta, Pasir, Senakin, Tanjung (Eocene) can be used as a minor component in coke blend.

In the last two years most of the coal production from eastern Kalimantan was allocated for exports but in the next few years an increasing proportion of production from this area is likely to be used for additional coal-fired plants in Java.

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