Hardrock a term used loosely for igneous and metamorphic rock, as distinguished from sedimentary rock. The hardrocks of Bangladesh are of four types: (i) Maddhyapara subsurface hardrock, (ii) Bholaganj-Jaflong hardrock concretions, (iii) Tetulia-Patgram-Panchagarh hardrock concretions, and (iv) Chittagong-Chittagong Hill Tracts sedimentary concretions. The items ii, iii and iv are usually considered as gravel deposits.
Maddhyapara subsurface hardrock In 1974-75 the geological survey of bangladesh (GSB) drilled six wells in and around Maddhyapara and confirmed the existence of Precambrian hardrock at very shallow depths. In these wells the Precambrian hardrock was encountered between depths of 128m and 154m. The depth of 128m was reported from well GHD-24. Techno-economic feasibility study of the Maddhyapara hardrock project was carried out by SNC (Surveyor Nenniger and Chenvert), a Canadian consultancy firm. In 1977, SNC opined that the project would be economically and technically sound and profitable. Finally, the Government of Bangladesh approved the project in 1978. However, the project started working formally from early 1994, following the signing of two international contracts for the Barapukuria Coal Mine Development Project and for the Maddhyapara Hardrock Mining Project between CMC of China and petrobangla, and NAMNAM of the Democratic Republic of Korea and Petrobangla respectively.
The Maddhyapara underground project is approximately 1.44 sq km. The hardrock are mined following the methodologies of room and pillar and sub-level stopping. In order to build up the mine, two shafts with a diameter of 5m each and set 240m apart will be installed. One of these (cage shafts), designed to reach a depth of 243m, will be used for carrying machinery and mine workers. The other one (skip shaft) with a projected depth of 287m will be used for transporting hardrocks. Insofar as the Dupi Tila Formation, which immediately overlies the hardrocks in this region,...
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