Post-Muckpile, Pre-Primary Crusher, Automated Optical Blast Fragmentation Sizing

Abstract

Automated rock sizing using digital image analysis has been well established. The methods work best under the controlled conditions of a conveyor belt, where camera angles and distances are constant, lighting is controlled, and sampling errors are at a minimum. Unfortunately, in most operations by the time rock is loaded onto a conveyor belt, it has passed through a primary crusher, and the size distribution no longer reflects only the blasting process. On the other hand, imaging and measuring the size of fragmentation on muck piles, while still useful, is problematic. Results can vary because of camera distances and angles, different lighting conditions can change measurements, and most importantly, because only the surface of the muck piles can be measured, tremendous sample bias can result in large measurement errors. The solution is to image the rock while in transit between the muck pile and the primary crushing station. This includes surface and underground HD (Haul Dump) and LHD (Load Haul Dump) type vehicles, using this method results in significantly decreased sampling errors. However new technical difficulties enter into the picture, including the need for advanced triggering and vehicle tracking mechanisms.