For the purposes of this PEA mining via conventional underground room and pillar mining with vertical shaft hoist was selected. The shaft would be located at the previous site location requiring rehabilitation of the shaft and installation of a new hoist.
Initial mining will occur within both the C and D sands. Mining in the C sand would extend for 10 years while the D sand would extend over 15 years.
Mining will be by room and pillar. General methods and assumptions include:
- Development drifts will utilize dual openings. 10 by 15-foot openings will be used for haulage, and 8 by 10-foot openings will be used for transportation and ventilation.
- Mining panels will utilize multiple entries depending on the width of the zone. Entries will be approximately 12 feet wide, minimum of 6 feet high and averaging 7 feet high.
- Crosscuts will be placed on 100-foot centers.
- Mining will be completed by advance and retreat methods.
- Advance mining is accomplished by driving approximately 12 by 7-foot drifts within zones meeting cutoff grade. Multiple drifts will be driven parallel to one another with crosscuts on 100-foot centers. The parallel drifts will be 27 feet apart on centerline.
- This will leave a pillar with a dimension of approximately 15 feet wide and 90 feet long. On retreat mining, these pillars are removed if they meet cutoff criteria.
- Mined material will be sized and sorted underground with the waste ........
