Drill-to-Mill: Efficient Drilling and Blasting Resulting in Increased Mill Throughput at Barrick Goldstrike
CIM Montreal 2003
Roy McKinstry, Thomas R. Bolles, P.E.,
Measurable improvements in throughput have been documented at Barrick Goldstrike due to increased ore fragmentation through efficient drilling and blasting techniques.
A decrease in throughput at the Autoclave, due to increasingly hard ore, was identified in early 2002. A team of individuals from the Open Pit and Process areas worked closely on the Drill-to-Mill (D2M) initiative to ensure that it would address the needs of both groups, with the target of actually improving throughput in future years, despite the projected harder ores. A series of tests were conducted to determine if adjustments to drilling and blasting could positively influence throughput.
Better fragmentation and a subsequent increase in mill throughput were achieved through the use of:
1) Electronic caps for more precision and flexibility, as well as for allowing extremely fast shots.
2) Explosives with a higher velocity of detonation (VOD), to provide for improved shock energy.
3) Improved distribution of the explosives by decreasing pattern spacing.
Early tests indicated a significant increase in throughput when processing identified harder ore. It is anticipated that the total process throughput (hard and soft ore) will increase by six tph in 2003 due to the improved fragmentation of the hard ore.
Barrick Goldstrike’s D2M initiative includes roaster “hard ore” (BWI >17), as well as autoclave “hard ore” (BWI >15). Approximately six million tons of D2M material is expected be shot in 2003, a relatively small amount compared to the 150 million tons to be mined. The benefit of additional ounces produced should far outweigh the additional drilling and blasting costs.