Drill and blast optimisation at the Hounde Gold Operations S.A., Burkina Faso.

Abstract

Evaluation of fragmentation remains an ever important discussion in the mining parlance as it is the first step towards mineral recovery. Predictions and estimation of blast induced fragmentation have significant importance, since these have direct impact on the downstream processes. Achieving the required fragment sizes after blasting is a major challenge at Hounde Gold Operation S.A (HGO). Blasting usually results in excessive proportions of boulders or fines which negatively affect productivity by increasing the downtime in loading, hauling and crushing. It also increases the cost of secondary breakage and the fines result in loss of gold. Optimal fragmentation will positively impact productivity and may reduce as much as possible the cost. The main objective of this research is to find optimum in-situ fragmentation to increase productivity at the lowest possible cost. For this purpose, a quality assurance and quality control (QA-QC) was done on the existing drilling and blasting procedures to identify the mistakes and modified drilling and blasting process were recommended for fragmentation improvement. Also digital images from blast shots were analysed using Split-Desktop software and results compared to those from Kuz-Ram model using the same design parameters. Because of its strong prediction ability, the Kuz-Ram model was used to predict the blast design parameters that would yield optimal fragmentation for the two different blocks (Block 1 and Block 2) identified at the Vindaloo pit of the mine where blasting activities are concentrated. Five images were picked for each block and analysed using Split Desktop software. The results were compared with Kuz- Ram and showed a variance falling between 1.24 % for Block 1 (in fresh material) and 7. 33 % for Block 2 (in transitional material). It confirmed that Kuz-Ram could be used to predict the incoming blasts. Therefore Kuz-Ram model was used to predict 3.6 m × 4 m drill plan (with a powder factor of 0.73 kg/m3 ) for Block 1 and 4.8 m × 5.1 m (with a powder factor of 0.43 kg/ m3 ) for Block 2. The proposed parameters would yield approximately up to 119 % lower oversize material, 42 % higher excavator productivity, lower crusher downtime, and 26 % reduction of the overall blasting cost