Pre-splitting is a controlled blasting technique with applications in open pit mines. The main objectives of pre-splitting in open pit mining are preventing/controlling back-break; controlling excessive ground vibrations; and filtering the effects of explosive gases from production blasting. This technique is especially effective in back-break control through providing a separating surface between the main blasting pattern and open pit final walls (Dindarloo et al., 2015).
Achieving a solid backbreak is essential for preserving wall stability and maximising blasting efficiency in mining operations. To establish a controlled fracture plane, pre-splitting entails drilling closely spaced holes along the intended final wall line, mildly charging them, then detonating them prior to the main blast. By guaranteeing a precise and well-managed cut, this method lowers overbreak, improves wall stability, and lessens vibrations from the ground.
However, this isn’t always the case. Even with an excellent pre-split, there are still other factors that will affect the backbreak, such as charge volumes, drilling angles and directions, and borehole lengths in the remaining blast pattern. If these factors are disregarded, the overall outcome will be unfavourable.
Bibliography
Dindarloo, S. R., Askarnejad, N.-A., & Ataei, M. (2015). Design of controlled blasting (pre-splitting) in Golegohar iron ore mine, Iran. Mining Technology. https://doi.org/10.1179/1743286314Y.0000000077
Pomasoncco-Najarro, A., Trujillo-Valerio, C., Arauzo-Gallardo, L., Raymundo, C., Quispe, G., & Dominguez, F. (2022). Pre-split blasting design to reduce costs and improve safety in underground mining. Energy Reports, 8, 1208–1225. https://doi.org/10.1016/j.egyr.2022.07.109