Vertical Crater Retreat
A vertical crater retreat (VCR), also referred to as vertical retreat mining, involves drilling large-diameter holes into the orebody vertically from the top of the mine, as opposed to the conventional blasthole stope method of drilling them in fans from bottom to top.
Vertical crater retreat is a beneficial mining method because it reduces the cost of mining orebodies that are wide and steep. It also eliminates the need for a support system after the blasting occurs and increases mining safety because miners do not have to be in the area of the ore when blasting is taking place.
Horizontal sublevels are constructed and the ore is extracted starting from the top level, requiring no hoisting system. After each subsequent level is stoped, ore is broken into horizontal slices by each successive blasthole. Once a hole is blasted, the ore at the bottom is loaded with more dynamite, resulting in further slices of ore breaking off into blocks until they fall to the bottom, the drawpoint level, and have to be mucked out. There is room in the stope for mucking to take place and the diluted or wasteful ore that is extracted along with the valuable ore is removed by blasting small sections of ore.Once the blasting is completed, LHDs muck the ore.
- Whyte, John and Cumming, John. Mining Explained. Northern Miner: Don Mills: 2004.