Fragmentation Control and Underground Automation

Abstract

Compared with modern longwall coal mining systems, automation has not been developed very far in the underground metal mining industry. One of the main reasons for this is that present hard rock raining systems do not produce ore with a controlled degree of fragmentation. The often poor fragmentation from the stopes causes large extra costs and precludes a continuous flow of material which lends itself to automation The paper investigates the possibility of adapting coal mining technology for automatic loading and transport of stope ore by conveyor belt to a shaft dump pocket. With this concept, it will be necessary to control the maximum fragment size by careful blasting design. The degree of fragmentation will have to be finer than is common to-day. The study shows that the belt conveyor mining concept with controlled fragmentation may be economically competitive with conventional cyclic loading and transport, even for an annual production as low as 0.5 mill, tonnes. Fragmentation design and cost calculations have been based on a combination of the Kuznetsov relationship between blasting parameters and mean fragment size, and the Rosin-Rammler formula for fragment size distribution