still for the mining of rock or ore in blockrasprincipen in massformiga bodies.

摘要

There is provided a method for extraction of rock or ore according to the block caving principle comprising driving, at several levels, principally straight, parallel and horizontal drifts into the lower part of a block, choosing the distance between the drifts at each level so that remaining supporting pillars will cover at least 40% of the block area, undercutting the block from the drifts in such a way that the drift openings toward the undercut area and the drift coverings will be arranged in steps, the drift openings being utilized as draw-points for the caving material and the number of drift levels being chosen with regard to desired horizontal distance along the direction of the drift between the draw-points at adjacent levels.