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 ?
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.
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.
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.