Web notes; MGEI on exploration for underground coal mining.
On the 20 April 2021, the Association of Indonesian Economic Geologist [MGEI] presented a webinar on Coal Exploration for Underground Mines, “Geologi dan Teknologi Bawah Tanah Batubara di Indonesia”, being the 4th in a series of coal webinars. The webinar was held in Indonesian. These are personal notes. I apologize for any errors or omissions.
Dr. Andy Yahya al Hakim (ITB) undertook the moderator’s role.
Noel Pranoto (BHP Australia), Coal Exploration for Underground Mine “Evaluasi Geologi Batubara untuk Pengembangan Tambang Bawah Tanah”. This presentation included examples from 2 underground coal mines in Australia. Touched on key geological considerations in collecting data, that define the seam, structural setting, and nature of the rocks above and below the coal seam that may impact on mining. Quantify geological hazards for mining & post mining, such as roof & floor heave, gas etc. Set out the exploration program in the phases of reconnaissance, then exploration, to include the basics such as mapping, down hole data, along with seismic, bulk sampling etc. This may lead to resource characterization. Mine development shall require closer spaced drilling, 3D seismic and more focussed technical studies. Get the most out of all data gathering programs, and retain samples for long term storage. The Australian experience is that underground coal mining deeper than 250m (from surface or major aquifer) may have little post mining subsidence issues. Critical roof & floor intervals are 2.5 – 3m.
Prof. Dr. Budi Sulistianto (IBT), “Teknologi Penambangan Batubara Bawah Tanah”. This presentation broadly outlined the basic mining methods for underground coal mining, including access, systematic mining, ventilation, along with various mining supports and coal mucking machines, plus surveying. Much of this presentation reflected the textbooks of the 1980’s. Budi shared some great historical small scale underground coal mining from Sawahluwung (W. Sumatra) in the 1990’s. Underground coal mining typically is undertaken from a depth of 50 to 900m.
Darius Agung (Kepala Balai Dikiat Sawahlunto), Peningkatan Kompetensi SDM untuk Manghadapi era Penambangan Batubara Bawa Tahna”. Darius started out with a review of the management structure of the Sawahlunto coal mine in West Sumatra [1916- 2013]. At present the Sawahlunto coal mine is a museum and training school for young engineers, and tradesmen. The organization structure for operating the mine required an engineer and geologist, 5 staff in the mine safety section, 8 registered mechanical & electrical engineers, plus about 60 workers.
· Darius outlined the aspect of standard competency required by the Mines Department. Kompetensi kerja (SKKNI, SKKK, SI) di bid Pertambangan Minerba. (Pasal 4& 5 Permen ESDM No. 42/ 2016).
· Training is ongoing at the Sawahlunto underground mining school. Balai Diklat Tambang Bawah Tanah, Jl. Soekarno-Hatta, Durian II, Barangin, Kota Sawahlunto, Sumatra Barat 27428, Ph (0754)61604.
Overview; This webinar acted as an introduction to this broad subject that may take some years to master properly. Much of the material presented represents early fundamentals. The industry of underground coal mining is well developed in countries such as Australia, China, South Africa etc. The technical training available at Sawahlhunto is a valuable resource for the future development of underground coal mining in Indonesia.
Managing Director - Mine Insight Pty Ltd
3 年Interesting that underground coal mining should come up as a topic as I am sure it will have to be looked at when economic recovery of older CoW and CCoW classified mines that still produce a major share of production become marginal / uneconomic. The photo take me back to my first job out of school working for the UK NCB in the 1970s with steel arch roadway support for single entry longwall operations. Just remembering that Ombilin/ Sawahlunto operation was mechanised in the 1980s by UK Government assistance through Dowty longwall supports (320t ) and a 200Kw AM shearer ... to put that into perspective a recent NSW longwall installed 1300t supports and a 1875Kw shearer but equipment was not the issue at Sawahlunto. Sawahlunto was the first mechanised underground coal mine in Indonesia but had the wrong geological setting for a consistent producing longwall with poor competence of immediate roof and floor materials and geological structures for consistent production which can be seen in its limited its width to under 140m ... (most Aus panels currently aim for 300m wide ). The only other underground operations I can remember were Kitadin (Embalut) which was hand worked with air picks and an interesting ride down the drift from surface and up stream at Fajar Bumi Sakti ...ah that Bumi name ?? The more recent failed Satui development should also be noted as any company looking at underground coal mining requires the right geological conditions/ environment for underground operations. That would include significantly more technical input/ cost ( geological and geotech) to assess a suitable ares for potential underground mining which would be a fundamental shift away from current practices for open cut operations.