CAVE MINING - THE STATE-OF-THE-ART

Caving is the lowest-cost underground mining method provided that the drawpoint spacing, drawpoint size, and ore-handling facilities are designed to suit the caved material, and that the drawpoint horizon can be maintained for the life of the draw. In the near future, several open-pit mines that produce more than 50 kt per day will have to examine the feasibility of converting to low-cost, large-scale underground operations. Several other large-scale, low-grade underground operations will experience major changes in their mining environments as large dropdowns are implemented. These changes demand a more realistic approach to mine planning than in the past, where existing operations have been projected to increased depths with little consideration of the change in mining environment that will occur. As economics force the consideration of underground mining of large, competent orebodies by low-cost methods, the role of cave mining will have to be defined. In the past, caving was generally considered for rockmasses that cave and fragment readily. The ability to define cavability and fragmentation, the availability of large, robust load-haul-dump units, a better understanding of draw-control requirments, improved drilling equipment for secondary blasting, and reliable cost data have shown that competent orebodies with coarse fragmentation can be exploited by cave mining at a much lower cost than by drill-and-blast methods.