SUMMARY

Discoveries of new, large, high grade ore deposits are still being made but they are increasingly rare. The mining industry is facing a general trend of decreasing reserve values and consequently lower revenues. Ore reserves are finite and new deposits are unlikely to be as valuable as those already discovered. As the largest and richest reserves are being mined out, there are fewer new ones left to find. Many smaller ore reserves have been identified but they are unable to support large scale mining. Yet as demand for most minerals is increasing and because small ore reserves can only be worked by small mines, it seems inevitable that there will be a resurgence in small and medium scale underground mining, to bring on stream these deposits.

Historically, mines had their individual favourite methods of working, techniques were based on local custom and practice rather than an open minded consideration of all possibilities. Today, narrowing of financial margins means every aspect must be questioned and careful planning of mining operations is crucial to achieve the most successful outcome. In this climate, mining engineers have to bear down on costs and productivity by maximising mechanisation, automation, new technology, better organisation and improved use of resources.

Successful mine planning involves deciding on the best options when several alternatives are available. Some choices are fundamental, for example whether to start or stop mining or to use surface or underground methods. Others choices include stoping method, sequence of extraction, output rate, shafts or drifts, tracked or trackless, development plan, optimising pumping, hoisting and transport.

Planning is somewhat different at small and medium sized mines. They tend to use smaller scale techniques – narrow vein stoping methods, small section developments, slushers, chutes, smaller gauge rail track, steeper drifts, rope haulages, short hole blasting, hand held drills, car and cage hoisting and so on. They are also more self-sufficient, relying less on external contractors. At the same time, lower grade ores and decreasing economies of scale mean that particularly high standards of mine planning are necessary for success.