Underground Hard Rock Mining, Drill And Explosion

2503 Words Sep 28th, 2014 11 Pages
1.0 Introduction
In underground hard rock mining, drill and blast continues to be the dominant method of fragmenting rock. Blast hole deviation is an inevitable yet undesirable outcome of small diameter, long hole drilling. The objective of drill and blast is to unlock a targeted volume of rock for removal and further downstream processing. However, if poor drill hole accuracy is observed, outcomes may be significantly different to that which are planned and expected, resulting in additional cost and time implications. A hole is considered to have deviated if it has not been collared at the correct location, has not followed the projected path or has not broken through at the intended position (Kangwa, 2000). Underground mining uses a cyclical methodology with repetitive steps carried out on a daily basis. As drill and blast is the first stage of extraction, the accuracy of this step can significantly impact the cost of downstream operations including secondary drilling, mucking, transportation, ground control, milling, development requirements and crew requirements (Corcoran, n.d.). This report intends to investigate the common sources of drill hole deviation, address the cost and design implications of poor drill accuracy and outline control measures that may be effective in reducing blast hole deviation. Different drilling technologies will also be examined to understand their impact on drilling accuracy.

2.0 Types of drill hole deviation
As described by Singhal…

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