There have been some notable successes in the development of mechanical underground excavation in hard-rock mines. Shafts are being constructed using shaft-drilling machines with shafts from 2 m to 6 m in diameter and to depths of 200 m to 300 m. Shaft drilling machines use fluid to flush the cuttings from the shaft face to the surface with reverse circulation dual wall drill pipe.

It has been apparent for many years that underground mining has needed a mobile, non-circular tunnelling machine for hard-rock mines. It is essential that such a machine use rolling cutters to fracture hard rock, since no version of a drag pick has been able to overcome the barrier of heat buildup and pick failure. In the mid-1970s, The Robbins Company began a development, using disc cutters, which they called the mobile miner.

Underground mining still needs a small, lightweight and inexpensive type of tunnelling machine like a mobile miner for hard rock. Many different versions of machines to achieve this objective have been designed and several different types have been built. However, the requirements for this type of equipment are extremely difficult to fulfill. The experience so far with the mobile miner, considering the amount of capital required for that development, does not encourage either mining companies

In order to take advantage of continuous excavation and mine mechanization, an entire mine, or at least a section of a mine, must be designed to operate continuously without the drill and blast cycle. There will be much new product development required before this can become a reality. Some ore bodies may require the development of a completely new mining system in order to overcome the environmental obstacles preventing exploitation.