Vertical crater retreat
From Queen's University Mine Design Wiki
This article is about the orebody requirements and developmental steps involved in Vertical Crater Retreat planning and mining.
Vertical crater retreat (VCR), also known as Vertical retreat mining, is an open stoping, bottom-up mining method that involves drilling large-diameter holes into the orebody vertically from the top, and then blasting horizontal slices of thethe orebody into an undercut.
Similar to Sublevel open stoping and Blasthole stoping methods, VCR mining is used for steeply-dipping (>45º), or both vertically and horizontally large orebodies with competent ore and waste rock strength. It differs from other open stoping methods in that it is a bottom-up method, as opposed to a left-to-right method, and it does not require the excavation of sublevel drifts before blasting and mucking can take place.Holes are typically 165mm in diameter, allowing for a blast pattern spacing of 4.0 by 4.0m, and the thickness of one slice of ore varies between 2 and 5m.