Vertical crater retreat method (VCR) is used at the deposits that have competent steeply dipping ore hosted by the competent wall rocks (Figure). The ground conditions in general is similar to that of the SLOS method, however the VCR is technically simpler and allows to achieve a large production rate commonly at lower production costs.
The method is based on the crater blasting which is made by firing the large diameter blast holes drilled downward from the overcut developed on the top of a stope (Figure). The blast holes are charged by explosives which is placed into the short sections of the holes which is referred to as crater charge.
The explosive is positioned in the each hole at the same distance above the open surface. The blasting loosens the ore slice of ore creating a crater which is vertically retreated. Ore is continuously extracted from the draw points together with rigorous recording of the blasting progress in each hole.
Author: Marat Abzalov
