9781439834220.ch4

9781439834220.ch4

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Unformatted text preview: dard self propelled rigs fitted with single or multi boom are available for their use in drivage work, tunnels and slopes with their mountings on rail bogies, rubber tired or tracked vehicles, as shown in figure 4.5. The drifter rock-drill is too heavy and powerful to be supported by a man, so it is mounted on a hydraulic boom, a column mounting or a portable mounting having crawler or wheel chassis. Drifters are used for the drivage work particularly the horizontal development work such as drifting, cross cutting and tunneling. They are classified as light, medium and heavy duty, as per the bore size, which ranges from 83 to more than 115 mm. These jumbos are designed for the specific tasks related to drilling at the development headings, tunnels and stopes. Today these jumbos are available for various purposes as described in the following sections. 4.6.1 TUNNELING/DEVELOPMENT DRILL JUMBOS1,3,4,5,7 The development mine entries such as levels, drifts, cross-cuts and sublevels; and civil tunnels may have varying cross sectional areas and gradient, and to suit these varying conditions different types of drill jumbos have been developed. For example, a jumbo of about 2.1 m width is used in the mines with narrow drifts, tight turns and frequent crosscuts. This type of jumbo is commonly known as Mini-bore jumbo. A jumbo5 with 2.0 m overall width is used for sublevel driving but it is capable to drill the faces as large as 9 m wide 4.5 m high.5 A jumbo having 2.4 m overall width is most common for its use in hard rock mining. It can also be used for rock bolting, room and pillar stoping operations. This jumbo can be used for drifts and tunnels’ configuration in the range of 3.7 m 3 m to 9.8 m 6.7 m. A typical jumbo, includes an energy system, operator’s station, chassis and boom equipped with a drifter or drill. Conceptual diagrams of hydraulic drifters have been shown in figure 4.5. © 2005 by Taylor & Francis Group, LLC DRILLING 69 4.6.2 SHAFT JUMBOS5 It is a compact unit designed to suit the narrow space available during shaft sinking operations. This jumbo is usually consists of a column with a horizontal top platform to which the drill booms are attached. The vertical column acts as the air header and the top platform serve as storage space for the hydraulic power unit. 4.6.3 RING DRILLING JUMBOS To achieve longhole drilling with maximum speed, accuracy and safety at low cost there has been consistent improvement in the design of ring drills. Earlier column and bar mounted ring drills have been replaced by single ring drill or the double (twin) drill ring jumbos either skid or pneumatic-tyred under carriages. The feed mechanism is either screw, chain or cable type. The mechanism for rotation is usually independent from the one governing the percussion, so that feed can be regulated depending upon the rock conditions. The controls are separated from the machine and can be placed remotely. The ring drilling work consists of drilling the blastholes radially from a drill drive keeping the drill at a fixed position in a plane that may be vertical, horizontal or inclined. 4.6.4 FAN DRILLING JUMBOS1,4,5,7 In sublevel caving the drilling work is considerably high and this calls deployment of highly productive drills. One to three boom jumbos are available for this purpose. A fan shaped drill hole pattern is drilled using these jumbos. 4.6.5 WAGON DRILL JUMBOS The main consideration in cut and fill stoping operations while selecting drilling equipment is the firmness of the fill, width and height of the working area of the stope. The pneumatic tyred three wheels, or four-wheel chassis carriers are used to mount the drills for this purpose. Air motors propel these carriers. Such drills are known as wagon drills. 4.6.6 DTH DRILL JUMBOS1,4,5,7 Besides their use as non-blasting holes (to provide free face)...
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This document was uploaded on 02/12/2014.

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