Blasting and drawing the ore on shrinkage to control hanging wall dilution and rib pillar
breach creat es the 23 in stope.
The VCR method of mining has reached the second stage with the beginning of rib pillar extraction.
Each rib pillar extraction created an almost unsupported span of 45m along strike, equal to three adjacent VCR panels.
When mining advances to within 10 m of the major fault, a 9 m wide panel with a 5 m wide rib pillar
configuration is used instead of post pillars.
splitting will take place by extracting 10m lengths of the pillar to leave 5m square pillars in situ.
The Alpine breaker line support (ABLS) is a self-propelled, hydraulic roof support replacing timber props currently used in pillar extration and rib pillar
Where South African longwall activity has been curtailed, it was not replaced by room and pillar mining but rather by pillar extraction or rib pillar mining.
That year saw the introduction of rib pillar extraction to the country, by Tata Iron & Steel.
As a consequence, the stability of the quarry structures and the geometrical parameters of the sill, crown, and rib pillars are strictly connected with the drifting depth, thickness and kind of cappings, and geostructural setting of the ore body.
For that reason, rooms and square pillars have been replaced by rooms and rib pillars with a smooth and regular profile of the mining walls (Fig.
Support is provided by 7-m wide rib pillars
left between the 10-m panels.
Each stope is 15 m wide, 100-150 m long, with rib pillars
18 m wide left between stopes for secondary mining.