1 st International Conference

Transcription

1 Coal Petrographic Study of Southeast Sulawesi 1 st International Conference Geoscience for Energy, Mineral Resources, and Environment applieds 2014 L.O NGKOIMANI 1, ANDI MAKKAWARU 2 and JAHIDIN 1 1 Jurusan Fisika Universitas Haluoleo, Jl. Edy Sabara No.88, 93122, Kendari, Indonesia 2 Dinas Energi dan Sumberdaya Mineral Sulawesi Tenggara, Malik Raya No.3,Kendari, Indonesia Laodem@yahoo.com, Makkawaru@gmail.com Abstract Coal is a one of potential Indonesia natural energy resources. Petrography study was commonly using on measure coal rank maturity through out reflectance vitrinite (R V). Petrography study on Southeast Sulawesi coal was from Lametusa area North Kolaka Regency. There 6 (six) sample were study, result shown that maceral composition of Southeast Sulawesi coal are tellocolinite, desmocollinite, densite, corpogelinite, cutinite, resinite, suberinite, semifusinite, sclerotinite, inertodetrinite and mineral matter (pyrite dan clay). Southeast Sulawesi coal rank from reflectance vitrinite from 0,23 0,25% with lignite catagory and level of maturity at Immature. Key word : Coal, Maceral, Reflectance Vitrinite. Introduction Coal is one of high potential of energy resource thatowned by Indonesia. Formation coal carrier (coal bearing formation) spread over an area of 298 million hectares in Indonesia, covering 40 basins in Sumatra, Kalimantan, Sulawesi, Irian Jaya and Java. Coal Basin in Sulawesi island itself formed during the Paleogene and Neogene (Cramer, Michael D, 2003). Coal research in Southeast Sulawesi, has been widely reported as by Surono (1993) at Surono (2010) and Dinas Pertambangan dan Energi Kabupaten Kolaka Utara (2008). Coal is an organic sediment that resulted from the accumulation of plants in a particular environment (Thomas, 2012). Formation factor (facies) Coal is closely related to the basin of deposition (sedimentary basin) and sediment filling the basin (sediment material). Coalization level determined from the dynamic development of the coal basin deposition. Dynamics of Southeast Sulawesi coal basin deposition will affect the level of maturity (rank) of Southeast Sulawasi coal. Dynamics that occur in a coal basin will change the pressure (P) and temperature (T) in a coal basin. Coal petrographic studies of Southeast Sulawesi is one way to learn the history of the basin dynamics. The level of maturity of the coal can be used to reconstruct the dynamics of sedimentary basins.

2 Coal petrographic studies are often used in measuring the level ofcoal rank, which can be seen through the vitrinite reflectance (RV) of coal. Vitrinite reflectance (VR) is a measure of the percentage of light reflected from the vitrinite maceral microscopis 500x magnification in oil immersion (Cardott, 2012). Reflectance measurements has been accepted and used to determine the coal rank quickly by physic properties of coal. The selection this method is based on the vitrinite reflectance: 1.Generaly maceral vitrinite has an enormous amount of coal. 2. Maceral vitrinite appearance under the microscope are homogeneous. 3. Vitrinite particles generally large so easier to facilitate in the measurement. Maceral in coal can be classified into 3 main groups (group) as vitrinite, liptinit and inertinit. These groupings are based on the morphology, size, relief, in the structure, chemical composition, color reflection, reflection intensity and level of coalification. The coal petrographic study of Southeast Sulawesi aims to recognize content of coal maceral, coal rank and to understand the depositional environment of the Southeast Sulawesi Coal. Methodology The research area is administratively in Southeast Sulawesi province with an study area around 25 km 2. The research area bounded by geographic coordinates between '7, 20 " '9, 34" latitude and '27, 13 " '58, 46" longitude. The research area is part of Southeast Sulawesi continental zone by Surono (1994) at Surono (2010) which form the mountains Tinondo (Tinondo line) to the southeast forming Mendokemountain range. This continent composed of metamorphic rock complex in the analysis by bothe (1927) and derover (1956) found 2 (two) periods of metamophic rocks, namely older metamophic rock and younger metamorphic rock. (Figure 1.) Older metamophic rock (Paleozoic formations) formed epidote-ampibolit facies, whereas for namely younger metamorphic rock produces glauchophane schist facies or commonly referred to as blue schist facies. The older metamorphic are assosiated with burrial process while younger are assosiated with geological structure that is associated with reverse fault that expected to occur during the tertiary period. This continent in overlapping by Molasa Sulawesi composed clastic sedimentary rock and carbonate. Clastic sedimentary rock composed Meluhu formation, whereas limestones Paleogene sediments consist karbonatan are namely Tampakura formations, Tamborasi formations and Lerea formations. The top of Molasa Sulawesi is unconformity layingof sequences quarterly rock, which consists of Buara formation and Allanga formation which is characterized by clastic sediments.(simanjuntak et al, 1993 at Surono 2010)

3 Coal petrographic study samples taken from Southeast Sulawesi coal belong in Lametusa district from North Kolaka region. Total of 6 (six) coal samples have been study of macerals content and their reflectance vitrinite. The equipment used in the coal petrographic studies are field equipment such as compasses and hammer geology, global positioning system (GPS), cameras, stationery and digging equipment. While the equipment used in the laboratory analysis is a microscope photometer size, S32 and LECO LECO AC 500 with standard testing based on ASTM Figure 1. the research areas geology simple modification from Geology Map Sheet Lasusua- Kendari issued by Geological Research and Development Centre, Bandung, Figure 2. The Morphology Basin of Research Sites using SRTM and Coal Samples location (dots) of Southeast Sulawesi Coal.

4 Results and Discussion Maceral Content of Southeast Sulawesi Coal Maceral composition of 6 (six) samples of Southeast Sulawesicoalare composed by tellocolinite, desmocollinite, densinite, corpogelinite, cutinite, resinite, suberinite, semifusinite, sclerotinite, inertodetrinite and minerals matter (pyrite and clay) (Figure 3 and 4). Desmocollinite and densinite is part of a sub-group vitrinit detrovitrinite is maceral dominate of coal sample.the amount of this composition around 24% -55.6%. Detrovitrinite or detrohuminite is come from huminite and coalification derivatives from wood fibers (woody tissue), which according to Koesomadinata (Koesoemadinata R.P dan Hardjono, 1977)is a constituent group of the main ingredients in Indonesian coal (> 80%). Based on the appearance of wood fiber types (woody tissue) that can be recognized well under microscopic observation, is indicates that coal is still in the stage of diagenesis and cause of the macerals shape is easier to distinguited so can be assume that fall into the category of low rank coal (low grade metamorphic) base on Degree Of Metamorphisme (DOM). Figure 3. Fotomicrographic of Sultra2 coal sample. 2A and 2C is the sample with white light reflectance while 2B and 2D are sample with flourescance mode. Looks detrovitrinite (Dv) is dominant vitrinite, and suberinite (Sb) of the group liptinit and mineral matter in the form of clay (Cl) that fills the gap vitrinite.

5 Figure 4. Fotomicrographic of coal Sultra4. 3A and 3C is a sample with white light reflectance while 3B and 3D are sampled with flourescance mode. Looks detrovitrinite (Dv) is dominant vitrinite, and Resinite (Rs) of the group Liptinit, Sclerotinite (Sc) of the group was evident Inertinit and mineral matter in the form of Pyrite (Py). Rank of Southeast Sulawesi Coal Coal rank is coal coalification that can be indicate changes in physical and chemical organic material due to an increase in the effect of temperature and time. Coal rank indicated can be approach by their vitrinite reflectance value (RV) of coal. RV values obtained from Southeast Sulawesi coal samples are varies with rangemean reflectance vitrinite from 0.17% to 0.26% (maximum reflectance = 0.30% and 0.19% minimum reflectance) for full view please see Table 1. Table 1. Composition maceral of Southeast Sulawesi Coal Maceral (% vol.) Reflectance Vitrinite SAMPEL Vitrinite Liptinite (Exinite) Inertinite Telocollinite Densinite Desmocollinite Corpogelinite Sporinite Cutinite Resinite Suberinite Alginite Semifusinite Sclerotinite Inertodetrinite Max. (%) Min.(%) Mean (%) Sultra 1 0,6 38,0 13,0 2,0 0,4 1,0 0,4 0,0 0,0 0,0 0,6 0,0 0,29 0,24 0,26 Sultra 2 0,4 8,6 15,4 2,4 0,0 0,6 1,0 0,6 0,0 0,0 2,0 0,0 0,30 0,21 0,25 Sultra 3 1,6 19,6 10,0 2,4 0,0 0,0 1,0 0,0 0,0 0,4 2,6 1,6 0,24 0,19 0,22 Sultra 4 0,6 23,6 32,0 2,0 0,0 0,0 3,8 0,0 0,4 0,4 2,6 1,6 0,25 0,16 0,21 Sultra 5 0,0 10,4 56,6 2,4 0,0 0,0 0,0 0,0 0,0 0,0 2,0 8,6 0,26 0,13 0,17 Sultra 6 0,0 3,2 67,6 1,6 0,0 0,0 0,0 0,0 0,0 0,0 1,6 12,0 0,23 0,14 0,18 Rv coal Southeast Sulawesi in the plot on the ASTM classification table (1981) is modified by techmuller and techmuller, show rank coal Southeast Sulawesi entered into the category of Lignite with maturity levels (oil generation) Immature based correlation table unpublished by MJ Johnsson.

6 Figure 5. Thermal maturity indicators. Approximate correlations modified from unpublished compilation by. M.J. Johnsson. Coal deposition environment of Southeast Sulawesi Based from plotting TPI versus GI chart into the importance of the value of the TPI (Tissue Preservation Index), GI (Gelification Index), which is nearly uniform and coal facies interpreted that the sample is the same sample. The results obtained plotting TPI vs. GI coal depositional environments of Southeast Sulawesi formed from wet peat with limnic depositional environment (Inundated Marsh) who is eutroph. Conclusion 1. Southeast Sulawesi coal maceral composition composed by maceral tellocolinite, desmocollinite, densite, corpogelinite, cutinite, resinite, suberinite, semifusinite, sclerotinite, inertodetrinite and mineral matter (pyrite and clay). 2. To rank coal based on the mean level of vitrinite reflectance ranges from 0.17 to 0.25% showed Southeast Sulawesi coal rank on rank lignite and organic maturity level into the immature category. 3. Based on TPI and GI value of the coal samples suspected sedimented in Southeast Sulawesi region limnic depositional environment that is eutroph.

7 Acknowledgements Thanks to Muh. Aryanto Embo, for his involvement in this study and Prof.Dr. Surono from Geological Survey Center for help in assisting laboratory Petrographic analysis of coal. Reference American Society for Testing and Materials (ASTM), 1994, Standard test method for microscopical determination of the reflectance of vitrinite in a polished specimen of coal: Annual book of ASTM standards: gaseous fuels; coal and coke, sec. 5, v. 5.05, D , p Cardott, 2012, Introduction to Vitrinite Reflectance as a Thermal Maturity Indicator, from presentation at Tulsa Geological Society luncheon. Cramer, Michael D, 2003, Coal Library Journal. 2/1/2003, Vol. 128 Issue 2, p.112. Dinas Pertambangan dan Energi Kabupaten Kolaka Utara, 2008, Laporan Penyelidikan Pendahuluan Batu Bara, Unpublished. Frumerman, and Harry. What s a coal Miner To Do?: The Mechanization Of Coal Mining. Library Journal. 1/1/1989, Vol. 114 Issue 1, p Hildebrandt L., and Langer H, 1988, Use Of COALDATA To Help Retyrieve And stimate The Physical Properties Of Coals, Coal Liquids And Coal Chemicals.Journal of Information Science: Principles & Practices. 1988, Vol. 14 Issue 5, p Koesoemadinata R.P dan Hardjono, 1977, Kerangka Sedimenter Endapan Batubara Tersier Indonesia, PIT IAGI, Bandung. Mueller, Rebecca, 198, Heating with coal/coal comfort, Library Journal. 12/15/1980, Vol. 105 Issue 22, p Park S.W, 1993, Coal Geology and coal petrology, Mineral Resources, Exploration and Development, Korea Institute of Geology, Mining and Materials (KIGAM), South Korea, p Piehl, and Kathy, 2008, Ethanol and other New Fuels/Nuclear Power/Oil, Gas and Coal, School Library Journal. Fall2008 Series Made Simple, Vol. 54, p Surono, 2010, Geologi Lengan Tenggara Sulawesi, Publikasi Khusus, Badan Geologi Kementerian Energi dan Sumber Daya Mineral, Bandung. Thomas L, 2002,Coal Geology, John Wiley and Sons, Ltd, England.