The intent of the Varistem® trial at Coal Mine X was to retain blast energy so as to minimize flyrock, noise and airblast. The trial block is situated in close proximity to a neighboring farm that falls within the 500m blast radius.
▪ Using actual drilling and charging data for individual holes, the Scaled Depth of Burial (SDoB) was calculated in order to understand what the expected levels of flyrock should be under normal circumstances (without using Varistem®).
▪ The average SDoB for the trial block was 0.53 – which based on theory should have resulted in the vast majority of holes producing violent flyrock.
▪ Contrary to the expected violent flyrock, the actual blast result showed excellent energy retention (in context of the very low SDoB value), with the furthest visible flyrock estimated to have reached no further than 100m away from the blast.
▪ Given the challenging nature of the block (average hole depth of 2m and average stemming height of 1m, with drill chippings as stemming), the blast result is highly
satisfactory and indicative of the Varistem® plugs offering great assistance in terms of mitigating violent flyrock.
Link to download case study. Reducing-Flyrock-with-Varistem-Case-Study
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