Solving the Problems of Precharging Sublevel Caving Rings atRidgeway Gold Mine

摘要

Ridgeway Gold Mine (RGM)is an underground sublevel caving (SLC)rnoperation that is owned and managed by Newcrest Mining Limitedrn(NML).Production drill and blast practices are critical to the success ofrnthe SLC method at RGM.SLC production ring precharging wasrnintroduced in November 2001 to enhance these practices and deliverrnsafety,productivity and cost improvements.rnCurrent precharging practices require up to two rings to be loadedrnahead of the ring to be blasted in each drawpoint.The explosive may bernrequired to remain in the up-holes for periods of four weeks or more priorrnto blasting.During this ‘sleep 'time it is subjected to repeated shock fromrnthe blasting ofadjacent rings and from rings in adjacent drawpoints.Thernproject described in this paper was designed to gain an understanding ofrnthe factors affecting explosive performance in the prechargingrnenvironment and to develop explosive products and operating practicesrnthat would meet RGM 's requirements in terms ofsafety,reliability andrnblast outcomes.rnSeveral months oflaboratory and field testing were required torncharacterise the explosive and quantify the effect of post-loading blastingrnshock.These results were used to determine the most appropriate loadingrnand sleep time criteria for RGM 's precharging practices.In addition,therninformation is being used to guide the development of the next generationrnof emulsion explosives for use in underground precharging operations.