Implementation of leading practice in geotechnical and blasting performance evaluations at the Centinela sulphide mine

Abstract

The Centinela sulphide mine (formerly known as Esperanza Mine) is an open pit sulphide deposit located in Chile's Antofagasta Region, 1350 km North of Santiago. One of the strategic objectives of the mine is to implement productivity improvement projects that can be monitored, adequately quantified and adhere to strict geotechnical requirements. This paper describes the implementation of leading practices to evaluate geotechnical and blasting performance. An approach based on direct measurements was developed and implemented at the mine site. The process involved measurements of near-field accelerations and gas penetration behind pre-split-lines; run of mine (ROM) fragmentation analysis and geotechnical evaluations based on the reconciliation of key geotechnical design parameters, such as bench face angle, berm width, inter-ramp angles and final slope characteristics. A geotechnical evaluation matrix was introduced to rank final results at each monitored location. From a geotechnical perspective, the best results were obtained with some of the lowest powder factor blasts monitored. Fragmentation assessment results showed that plant requirements were still being achieved at these lower powder factors. This helped confirm that in the rock mass domains of interest, reduced powder factors in production rows were more appropriate in order to maintain higher standards of quality in wall control practices.

Keywords:

• Geotechnical assessment
• Pit geometry
• Pit slopes
• Blasting
• Pre-split practices
• Wall control
• Blast-induced damage
• Fragmentation evaluation