The Creighton deposit consists of the actively mined 310, 400, 461 orebodies and the inactive Creighton Deep 404, 315, 320 and 6100 zones.
Slot–slash and Vertical retreat mining methods are employed for ore extraction. Also common is Transverse stoping.
Mill rock tailings are used for backfilling.
Slot–Slash
Slot–slash mining is a bulk mining method that entails blasting vertical slices of ore to a free face, which initially will be a blasted inverse raise, or a bored raise. The amount of ore that can be blasted at any given time is limited to the existing void space and the available free face. Blastholes are loaded with staggered decks to break anywhere from 6 m to the entire length of the hole. The blocks are slashed out to the stope boundaries and up to a crown. The final crown is taken in one blast.
This method concentrates loading and blasting operations, and, once a slot has been established, stopes of 25,000–40,000 t of ore can be completely broken in 3–5 separate blasts, while smaller stopes can be blasted in one blast.
Blastholes are drilled using in-the-hole (ITH) drills. Prior to blasting, long blastholes are surveyed in order to determine their location and all holes are probed with a conductivity probe to confirm ore limits. If required, new holes are drilled to reduce burdens created by drilling inaccuracy and to blast additional ore found during the conductivity tests.
Slot–slash mining ........