The other one is used to provide an initial free face

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Unformatted text preview: ay. The other one is used to provide an initial free face for the stoping operations to start with in some of the stoping systems. This is known as slot raise. The dimensions of a service raise depend upon its utility. It can be divided into number of compartments. One of them is usually a stepladder man-way and others are intended for discharge of ore to the lower haulage horizon, lowering of fill from the upper horizon, delivery of material, and ventilation. Vertical raises are more expedient because of small wear to the sides, more convenient transportation of men and shorter length. The raises driven should be able to provide a safe © 2005 by Taylor & Francis Group, LLC EXCAVATIONS IN UPWARD DIRECTION – RAISING 333 Raising techniques Blind raising Open raising Compartment method Two levels available Alimak raise climber Jora hoist Longhole raising Drop raising Raise borers Figure 13.2 Classification of raising methods/techniques based on the availability of access to the intended raise site at the time of its drivage. access to the stopes and minimum cost of their driving and repair, and good ventilation of the stoping faces. Raise placement w.r.t. orebody is governed by the purpose it needs to serve and based on this logic it could be placed within orebody, following the profile of orebody, half in ore and half in the contact rock and away from the orebody (usually in f/w side), as shown in figure 13.1(ii).1 The raises need to be preserved for a longer duration is usually located in the country rock on f/w side. Raises meant to serve, as an ore pass should have inclination of at least 60°. Apart from the stoping sections, the raises are now a days driven to act as ore passes, waste passes, backfill inlets, ventilation inlet or returns and emergency access to the mines from surface to underground or from one horizon to others within a mine. To summarize, in underground mines the applications include: 1. Ventilation access (for the whole mine) 2. In stopes: Ventilation, Services (to accommodate supply lines, ladder ways, material hoisting etc.) 3. In some stoping methods as a slot raise it provides initial free face and others for creating funnels, and also as fill pass, drainage tower, ore pass and man-pass. 4. Waste and ore passes for transferring waste rocks and ores from one horizon to other. 5. Emergency escape 6. Pilot for shaft sinking. Raises could be put as ore passes to haul up the production from deep-seated open pit mines, as shown in figure 17.16(e)1. 13.4 RAISE DRIVING TECHNIQUES The raises, for the purpose of their driving can be classified as: Blind and the raises that have two levels available to access them. The former is difficult to drive than the later one. The other classification can be based upon with and without use of explosives while driving them. The line diagrams, in figures 13.2 and 13.3, presents the classification based on both these criterion. The techniques in use have been described in the following sections....
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