Master of Science (Hons.)
Department of Geology
Sutarwan, Achmad Hakim, Petrographical and chemical properties of coals from the Southern Peranap deposit Central Sumatra Basin, Indonesia, Master of Science (Hons.) thesis, Department of Geology, University of Wollongong, 1995. http://ro.uow.edu.au/theses/2833
The present study is located in the Southern Peranap coalfield, Central Sumatra Basin. The economic coal deposite occurs in the Korinci Formation which is of a Late Miocene to Pliocene age. The Korinci Formation contains the P2, PI, Lower P(LP), Upper Q (UQ), Q2, Ql, Lower Q (LQ) and R seams (youngest to oldest). The aims of the study were to evaluate the quality, chemical and physical properties including petrographical characteristics. A fundamental aim was to assess the potential utilisation of the Southern Peranap coal. Petrographically, vitrinite is the dominant maceral with average vitrinite content 91%. Vitrinite comprises mostly telovitrinite (range of 32% to 60%, average of 43%) and detrovitrinite (range of 25% to 49%, average of 40%) with minor gelovitrinite. Textoulminite is the dominant telovitrinite maceral whereas densinite is the dominant detrovitrinite maceral. Liptinite is common in Southern Peranap coal ranging from 2.4% to 13% with an average of 7%. Liptodetrinite and resinite are the dominant macérais in all samples. Minor liptinite constituents comprise cutinite, suberinite, sporinite and rare exudatinite and fluorinite. Inertinite content of Southem Peranap coals is generally low ranging from 0.2% to 4.5% with an average of 2%. The dominant inertinite macérais are semifusinite and sclerotinite, with minor fusinite, inertodetrinite, macrinite and micrinite. There is no significant differences in coal composition between the seams. The Southem Peranap coals are of brown coal rank with mean maximum vitrinite reflectances (R^max) mostly in the small range of 0.28% to 0.30% with some values up to 0.40% in the deeper parts of the sampled holes. Coals from Southem Peranap developed from ombrogenous mires source by tropical rain forest vegetation on fluvial floodplain environment. There is evidence of brackish water or marine water influence in some parts of the sequence. The coals are hydrogen-rich coals with an average of 5% hydrogen and H/C ratios >0.75. Carbon and oxygen contents range from 69% to 71% and from 22% to 25% respectively. Sulphur and nitrogen are typically low, usually less than 1.0%. Sulphur is mostly in form of organic sulphur (typically >60% of the total sulphur). Moisture contents of Southem Peranap coals ranges from 10% to 22% (average of 16%). Silica (Si02) and alumina (AI2O3) are the dominant constituents of the ash. The Sodium (Na20) contents of the ash increase from the youngest to the oldest seam. The hardgrove Grindability Index (HGI) ranges from 43 to 58 HGI units. Southem Peranap coals are believed to be environmentally safe due to the expected low emissions of NO^ (630 ppm), SO, (108 |Lig/m^) gas and particulate matter (9.5 kg ash/T m^) from buming these coals. These values are within the World Health Organisation acceptable levels. The Southem Peranap coal are suitable for use in coal conversion prosses, such as gasification, and combustion due to the presence of highly reactive macérais and a high volatile content.