shaft pillar

shaft pillar

[′shaft ‚pil·ər]
(mining engineering)
A large area of a coal or ore seam which is left unworked around the shaft bottom to protect the shaft from damage by subsidence.
References in periodicals archive ?
The overall direction of mining is from the shaft pillar outwards, moving from raise line to raise line out toward the boundaries.
By August 1992, development on the Ventersdorp Contact Reef in the South Deep shaft-pillar area was completed, this allowed the stoping of the reef and stabilisation of the shaft pillar ahead of shaft sinking operations.
Whichever is chosen, some ore will be sterilized by a shaft pillar. Both the additional depth and the need to ensure stability of the existing shaft complex while minimizing the tonnage of sterilized ore make stress analysis imperative.
Tenders are invited for Construction Of Sidewall To Prevent Spalling Of Shaft Pillar As Well As To Strengthen The Girder Support Against The Roof At No 7 Pit Bottom In Narainkuri Seam (R -Vii) Of No 7 Pit Amkola Unit Under Nimcha (R) Colliery.
3.) Because the strata is not disturbed by blasting it should be possible to leave smaller shaft pillars which at present often sterilize considerable tonnages of ore.
Considerable tonnages of coal left in shaft pillars are now being recovered by open-pit methods.