... Crush pillars have been extensively applied on the Merensky Reef horizon since the late 1970's. Once in a crushed state, the residual strength of the pillar provides a local support function and must support the hanging-wall to the height of the highest known parting. The design process of crush...

... Mining in the Carletonville area of the Witwatersrand Basin predates 1934. Owing to the depletion of higher grade ore, the current activities focus increasingly on the extraction of lower grade secondary reefs as well as remnant and pillar extraction. Of particular interest is multi-reef remnant...

... In mining, the design of optimum pillar strength has benefits ranging from increased extraction ratio (economic benefit) to the stability of the hanging-wall (safety benefit). Pillar strength is traditionally determined by empirical calculations and based on square, or near-square, pillar shapes...

... Shallow hard-rock bord-and-pillar mine designs are typically characterized by solid pillar systems and stable span designs. These spans are optimized to maintain stability, which permits safe and economic extraction of the orebody. Reef-parallel structures are known to affect the strength...

... In a previous study, the authors investigated the cable-strapping of pillars in room and pillar mines in order to solve local instability problems, by conducting laboratory tests. Based on experience in an old, small room-and-pillar haematite mine in Spain, the authors suggested a few steel...

... In order to improve the extraction ratio at a hard-rock mine, the partial post-extraction of strike stabilizing pillars was considered as an option at a concept level of study. An evaluation of the potential revenue based on a maximum extraction of up to 50% of the pillars was carried out, which...

... A study was undertaken to investigate the potential to increase the overall extraction ratio through safe partial mining of the existing underground pillars on the No. 4 Seam at a colliery located in the Witbank Coalfields using a modified NEVID system. A bord and pillar mining layout...

... of life. The availability of locked-in reserves in pillars or remnants provides an opportunity for supplementing the declining production profiles and extending the life of these mines. In this paper, we provide an overview of current remnant mining practices in South African gold mines. The factors...

... studies conducted using FLAC3D to arrive at a feasible stoping sequence for maximum ore recovery. The sequence finally suggested involves an upward mining sequence using primary and secondary stoping configurations with sill pillars and vertical (rib) pillars. The influence of stoping, as seen...

... Severe instability in an underground hard-rock bord and pillar mine situated on the Great Dyke in Zimbabwe necessitated a thorough revision of the existing design. Local geotechnical conditions characterized by undulating, subhorizontal and intersecting shear structures, variable in thickness...

... FLAC3D was employed to assess pillar and panel stability for a partial stooping operation at a coal mine in South Africa, where the main requirement was that ground surface stability be ensured. The stability of square and rectangular pillars was assessed using a strain criterion linked...

... Bore-and-fill mining was implemented at a pilot site in Tau Tona mine's shaft pillar on 97 level. Observations, scan data and measurements from this site were used to calibrate an inelastic numerical model of bore-and-fill mining within the carbon leader reef (CLR). Borehole breakout was found...

... The design of support pillar layouts in shallow South African mines has historically been based on comparisons of pillar strength to pillar loading, providing some acceptable factor of safety. For this evaluation of pillar stability, empirical strength formulae were compared to either tributary...

.... CASE STUDIES 1 AND 2: PLATINUM AND DIAMOND MINES Introduction A platinum mine in Southern Africa and a diamond mine in North America experienced similar instability associated with a weak (shear) layer in either the pillar foundations or within the pillars themselves. In the one instance...