Step 4 - Equipment: Drilling Drilling Equipment (SeeSummaryfor main points) Production blastholes for mining or quarrying typically are drilled using crawler mounted percussion drills (Figure 1, below left) or rotary drills (Figure 2, below right). The use of percussion drills is generally confined to smaller operations with production rates less than a few thousand tonnes per day. Rotary drills are used for production drilling at most larger scale operations where blasting is required. For purposes of our cost estimate, drill ing for production of ore and waste should each be considered separately because rock conditions and production requirements for one may differ considerably from those of the other. Upon completion of the separate analyses, a judgment call should be made to decide if the same equipment can be used to drill both ore and waste, keeping in mind that the distance between the two operations i n an operating pit may be so great that utilization of the same equipment units for each may be impractical. The objectives for our analysis and selection of drilling equipment for cost estimating purposes are as follows. 1. Select the appropriate type and size of drill(s) required based on the information we have available about the rock characteristics and the proposed operation. 2. Determine the number of hours our drill(s) must operate per day to meet production requirements. 3. Determine the number of drills required to fulfill the daily requirements. 4. In conjunction with the drill selection procedure, determine the daily requirements for drill bits, drill steel, primers, caps, and explosives. By the time our mine goes into production, considerable test and design work will have been completed to determine ore and waste drilling and blasting characteristics, powder requirements, and preliminary bench height and blasthole drill patterns. At the time of our preliminary cost estimate, however, we may have little or no information available other than rock types and our
