Deep hardrock mining-the future

摘要

The most important factor in Canadian mining is not the operating cost of current pro-jects but the availability of capital for future pro-jects. The future of mining at depth will be producing ore from the top of the orebody wording downward with very effective, tightly controlled mining methods, i.e. either selective mining or bulk mining with well controlled dilution and fragmentation. The key characteristics of future mines will be smaller access excavations, more effective ground support, very precise blasting techniques and more efficient and reliable materials handling systems. Equipment will be smaller and designed for high efficiency and low maintenance, reducing both the capital and operating cost. This means there will be fewer scoops, more continuous mucking machines and conveyor belts, both lateral and vertical.Orepass failures have become accepted and the resultant redevelopment and re-tram-ming has become common. The capital invest-ment in so-called permanent orepasses and crusher stations becomes questionable, particularly when crushers are only necessary for less than 10 percent of the ore going through the system. The best way to solve the chronic instability of orepasses is, as with all of the stability problems at depth, by reducing the excavation size rather than increasing ground support. Smaller access drifts would reduce the capital cost and increase the rate of development as well as reduce the amount of waste to be handled, reducing the ground support and the ventila-tion requirements. Large drifts and orepasses are essential only for the equipment needed to handle large pieces of ore and the productivity of scoops is very expensive when the require-ments for ventilation and large access drifts are taken into account. The key issue is the fragmentation generated by primary blasting.