Southern African underground Platinum and Chrome Mines exploit the tabular platinum- and chrome-bearing orebodies using either conventional mining methods making use of jackhammers and air legs, mechanized bord/room and pillar mining layouts or a combination of the two, locally referred to as Hybrid mining methods. There have been a number of large-scale collapses in the bord/room and pillar operations in South African underground platinum and chrome mines. Investigation into these high-lighted deficiencies in either or both pillar and bord hangingwall tendon support designs. Unfortunately a couple of these collapses resulted in the death of 14 employees. Investigations into the cause of these collapses identified a number of failure modes – either in the pillars, bords or both. In all cases, the lengths of tendons used exceeded the theoretical tensile height for the bord. This paper will highlight the tendon support design philosophies commonly used in these operations and the identified failure modes that have occurred in the bord and pillar workings in the South African underground platinum bord and pillar operations.
Platinum mining in the South African mining industry typically occurs in both the opencast/surface and underground mining environments. Historically, both the UG2 chromitite and Merensky pyroxenite reefs were exploited, with exploitation of the Platreef having commenced in the Limpopo Province (Northern Limb of the Bushveld Complex) within the last decade, predominantly from the openpit or surface mining environment. The UG2 and Merensky platinum-bearing reefs have been mined extensively on the Western limb of the Bushveld Complex. Underground mining operations on the Eastern Limb of the Bushveld Complex have been ongoing for the approximately past 10 years. Numerous attempts have been made at implementing a fully mechanized underground mining operation on the UG2 and Merensky reefs in the underground platinum mines in the Bushveld Complex.