Sub Level Caving

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  • Topic: Mining, Drilling rig, Rock
  • Pages : 11 (4341 words )
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  • Published : April 21, 2013
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Sublevel caving techniqueSimplicity and low cost are the essence

SUBLEVEL CAVING TECHNIQUE
SIMPLICITY AND LOW COST ARE THE ESSENCE Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering, E.mail: sharmapd1@gmail.com, Blog/Website: http://miningandblasting.wordpress.com/ 1. Introduction - Sublevel caving is usually carried out when mining of the orebody through an open pit method is no longer economically feasible. Mining now proceeds underground, underneath the open pit. At first, both a raise and a network of tunnels are made. At different sublevels, jumbos are used for long hole drilling, drilling directly upwards into the roof. These holes are then charged with explosives and blasted. As the roofs cave in, the rock from the ground surface will cave in to the underground as well. Scoop trams or Load Haul Dump (LHD) vehicles transport the muck, loosened rocks, to an ore pass where the rocks are lifted to the surface. Drilling and blasting takes place at different underground levels of the mine at the same time. As the blasted rock, muck, is continuously transported to the ore pass, more blasting will encourage the roof to cave in to the void and further into the drift. This is repeated until blasting, caving and transporting depletes the entire orebody.

2. Modern day Sublevel caving - The sublevel caving technique, as the method is applied today, the whole quantity of ore between the different sublevels is broken using ------------------------------------------------------------------------------------------------------Author: Partha Das Sharma, E.mail: sharmapd1@gmail.com, Blog/Website: http://miningandblasting.wordpress.com/ 1

Sublevel caving techniqueSimplicity and low cost are the essence controlled drilling and blasting. Sublevel caving is in many respects simple. It can be used in orebodies with very different properties and it is easy to mechanize. In sublevel caving, ore is developed from a series of sublevels spaced at regular intervals throughout the orebody. Mining begins at the top of the orebody. A series of ring patterns is drilled and blasted from each sublevel. Broken ore is mucked out after each blast and the overlying waste rock caves on top of the broken ore. This technique is inexpensive, highly mechanized and yields a large amount of muck. It is normally used in massive, steeply-dipping orebodies with considerable strike length. Since dilution and low recoveries are unavoidable, sublevel caving is used to mine lowgrade, low-value ore-bodies. However, studies are going on in various levels to eliminate the shortcoming of the system. The designs which are used and the measures which can be taken to eliminate the disadvantages are less understood. Possibly the modern version of the method was developed in the iron mines of Sweden. Over the past few years, the scale of sublevel caving has increased markedly with LKAB being a leader in this regard. Today, with the continuing push to increase mining scale, a fundamental question is whether the gravity flow principles which served as the design basis for the small-scale sublevel caving mine designs of the past can be applied at much larger scales or whether some other approach is required. In fact, in design and operating practices, sublevel caving is among the most advanced of all mining methods. Sound engineering is indispensable to its conduct. The reason is related to the complexity of the caving action and the necessity of controlling it.

The increased sublevel interval requires diligence in drilling, loading and blasting practices. The advent of improved drilling technology has made increased sublevel intervals possible in the sublevel cave mine. Hydraulic tube rod drill rigs have made long ------------------------------------------------------------------------------------------------------- 2 Author: Partha Das Sharma, E.mail: sharmapd1@gmail.com, Blog/Website: http://miningandblasting.wordpress.com/

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