Indonesian coal was upgraded by upgraded brown coal (UBC), hot water drying (HWD), and steam drying (SD) processes to study the combustion characteristics of this coal. The differential thermal-thermogravimetric analysis (DTA-TG) was carried out to obtain some combustion parameters, such as, ignition temperature (T ig ), maximum combustion rate temperature (T max ), maximum combustion rate (R max ), char burn-out temperature (T bo ), and ash yield. The differential thermal analyzer (DTA) curve can be used to estimate the heat released during the combustion process, which corresponds to the high heating value of the coal. The results show that the combustion characteristics of HWD and SD processes are much better than those of the UBC process. This is because the UBC process was conducted at lower temperature and pressure.

ABSTRAKBatubara yang cocok untuk kegiatan gasifikasi bawah permukaan harus memenuhi persyaratan, antara lain kondisi geologis, ketebalan, kedalaman, kadar air total dan kadar abu. Berdasarkan persyaratan ini, tidak semua batubara dalam bisa dimanfaatkan untuk kegiatan gasifikasi bawah permukaan. Kegiatan eksplorasi batubara perlu dilakukan untuk meminimalisasi risiko geologis dan untuk mengetahui kondisi batubaranya. Berdasarkan hasil permodelan, ditemukan lapisan batubara D dengan kriteria kedalaman 200-300 m, ketebalan >5 m, kadar total air lembab+kadar abu <60%, nilai kalor 4.912-6.275 kkal/kg, reflektansi vitrinit 0,23-0,44 (lignit-subbituminus). Perhitungan sumber daya batubara dengan menggunakan software yang ada dan mengacu pada aturan SNI 5015-2011, menghasilkan sumberdaya tereka 3.316.578 ton, tertunjuk 1.909.560 ton dan terukur 2.479.951 ton.Kata kunci: batubara macang sakti, kualitas, gasifikasi batubara bawah permukaan, perhitungan sumberdaya. 4,912-6,275 kcal/kg, a vitrinite reflectance of 0.23-0.44 (lignite-sub bituminous). Calculation of the coal resource is conducted by using software and applying SNI 5015-2011, resulting in inferred resource of 3,316,578 tons, indicated resource of 1,909,560 tons and measured resource of 2,479,951 tons ABSTRACT

Selected Tertiary coals from the western part of Indonesia (Sumatera, Kalimantan and Java) indicate similarities and differences in type and rank characteristics. These coals reflect their geological setting, particularly for intrusive and stratigraphic aspects. Type and rank of the coals were assessed by petrographic examination. The coals are mainly dominated by vitrinite, common liptinite and rare inertinite and mineral matter. Vitrinite macerals are dominated detrovitrinite and telovitrinite. Resinite, cutinite and suberinite are the dominant liptinite macerals in the coals. Inertinite macerals in the coals consist of semifusinite, sclerotinite and inertodetrinite. The type differences largely reflect climatic influence and differences in peat conditions. In spite of short geological history, the coals exhibit variable vitrinite reflectances. The high vitrinite reflectance of the coals is a result of higher regional coalification levels in the basins associated with greater cover and effects of igneous intrusions.Keywords: coal, maceral, type, rank, western Indonesia. ABSTRAK Percontoh-percontoh batubara yang terdapat di Indonesia bagian barat (Sumatera, Kalimantan dan

Kendilo coal is known as a high-ash content type. Beneficiating such the coal for gasification process needs to wash the coal first. The purpose of washing is to lower the ash content until the permitted amount of about 10%. Samples for coal washing were obtained from PT. Kendilo Coal Indonesia at Pasir Belengkong, Paser Regency, East Kalimantan. The samples were taken at Bindu and Betitit Block, which containing ash of about 20%-30%. To wash the coal samples, a sink-float method was applied to test its separation characteristic. The washing process employed three sizes fraction, i.e, -12.5+5.6, -5.6+1.18, and -1.18 mm and the separation density was varied between 1.3 to 1.6 g/cc within the interval of 0.1. The liquid solutions as the separation media were made from mixing of perchloroethylene and toluene. From the coal washability curve, the best coal washing in order containing ash content of about 8% in the case of Bindu Block's coal, occurs at the fraction of -12.5+5.6 mm, at density separator of 1.36 g/cc with the recovery of 50%. While the coal of Betitit's Block, the washed coal was 50.82% at similar fraction but at different density separator of 1.39 g/cc.Keywords: coal washability, sink and float test, recovery, coal washability curve fraksi ukuran, yaitu -12,5+5,6; -5,6+1,18; dan -1,18 ABSTRAK