Limits Excavation at Mt Whaleback

Within the Mt Whaleback open cut mine the integrity of the final pit wall is achieved through careful rock slope design, use of rock reinforecement technology where marginal stability exists and use of controlled blasting techniques and excavation practices. By reducing the effective density of ANFO explosive within blastholes to around 0.2 glcm', and developing standard blast pattern designs for various rock types, blast damage to pit walls has been minimised. Accurate geological prediction is necessary for optimum blast design. Controlled blasting is undertaken where blasting occurs within 90 m of the designed final batter crest and hole by hole assessment of final limit blast patterns is undertaken before pattern charging. Shovels and trucks remove the bulk of blasted and dozed rock material, but due to the mine's variable pit wall slope configuration, bulldozer excavation of some critical design batters has been successfully Implemented.