Studi Pengaruh Thermal terhadap Kekuatan Batuan di Lokasi Underground Coal Gasification, Desa Macang Sakti, Kecamatan Sanga Desa, Kabupaten Musi Banyuasin, Provinsi Sumatera Selatan

Reynaldi Reynaldi, Yuliadi Yuliadi, Bagaraja Sirait

Abstract


Abstract. The Technology Underground Coal Gasification method is a technology will do the in-site coal extraction in form of gass, by direct combustion at the coal seam. However, environmental concerns arise as the combustion process might cause land subsidence due to the occurrence of cavities in the coal seam after combustion. This study was carried out by an experimental method and focused on side rocks surrounding the coal seam which consisted of sandstone, siltstone and claystone. Rock samples were heated in temperatures that vary from 50oC, 100oC - 600oC for 24 hours in the furnace. Uniaxial Compressive Strength test was performed on the samples afterward to determine the changes in rock strength after combustion process is complete. Based on the results, rock sample’s physical condition shows a deflationary trend towards rock density after heating, due to the loss of water content that causes fractures on samples. That condition will cause changes in rock strength and lead to land subsidence around the coal gasification site. The most significant changes in rock strength occurred in sample 3 which is sandstone sample where the rock strength before heating is 15,64 MPa and enhance to 41,70 MPa after being heated. Sample 5 which is claystone sample also shows strength enhancement from 6,76 MPa to 20,40 MPa. The results of rock displacement test performed in before-heated-sample show the highest rock displacement of 18,40 cm and 1,60 cm at the lowest. As in after-heated-sample, the results show the highest rock displacement of 9,45 cm and 0,45 cm at the lowest.

Keywords: Underground Coal Gasification, Subsidence Land, Rock Strength

 

Abstrak. Teknologi Underground Coal Gasification merupakan teknologi untuk mengekstraksi batubara menjadi gas yang dilakukan secara in-situ, dengan melakukan pembakaran langsung pada lapisan batubara. Tetapi muncul kekhawatiran pada bidang lingkungan, yaitu terjadinya penurunan tanah yang diakibatkan dari terbentuknya rongga pada lapisan batubara yang telah selesai proses pembakaran. Penelitian ini dilakukan dengan metode eksperimen dan terfokus pada lapisan pengapit batubara yaitu batupasir, batulanau dan batulempung. Sampel batuan akan dipanaskan dari suhu 50oC, 100oC - 600oC selama 24 jam di dalam furnace. Setelah di lakukan pemanasan, di lakukan pengujian Uniaxial Compressive Strengh untuk mengetahui perubahan kekuatan batuan yang terjadi setelah selesai pembakaran. Berdasarkan hasil penelitian, kondisi fisik pada sampel setelah dipanaskan memiliki trend penurunan terhadap nilai density, hal tersebut di akibatkan dari hilangnya kadar air dan menimbulkan retakan kecil hingga besar pada sampel. Hal tersebut akan mengakibatkan perubahan kekuatan batuan, dalam penelitian ini karena kekuatan batuan mengalami penurunan sehingga akan terjadi penurunan tanah di sekitar lokasi penambangan dengan metode Underground Coal Gasification. Perubahan kekuatan batuan yang paling signifikan pada sampel 3 pada litologi batupasir sampel sebelum di panaskan memiliki kekuatan batuan sebesar 15,64 MPa dan meningkat menjadi 41,70 MPa, selain itu pada sampel 5 dengan litologi batulempung terjadi peningkatan dari 6,76 MPa menjadi 20,4 MPa, sehingga ketika analisis perpindahan batuan sampel yang sebelum dipanaskan akan memiliki perpindahan batuan yang besar dengan nilai perpindahan tertinggi 18,40 cm, terendah 1,60 cm sedangkan untuk batuan setelah dipanaskan perpindahan terbesar 9,45 cm dan terendah 0,45 cm.

Kata Kunci :  Underground Coal Gasification,  Penurunan Tanah, Kekuatan Batuan



Keywords


Underground Coal Gasification, Penurunan Tanah, Kekuatan Batuan

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DOI: http://dx.doi.org/10.29313/pertambangan.v0i0.14854

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