Mining
The Optimum Methodology for Conducting High Resolution, Shallow Reflection Seismic Surveys on South African Collieries
2001
Field procedure standards for high resolution seismic work over seams 30 to 100 m deep, trialled at two Mpumalanga collieries, with a cost comparison against exploration drilling.
What this report foundShallow reflection seismic surveys failed on South African collieries mainly because too little preliminary data, from vertical seismic profiles and noise...
R1500,00
Shallow reflection seismic surveys failed on South African collieries mainly because too little preliminary data, from vertical seismic profiles and noise spreads, was gathered before the surveys were designed. Following the field procedures set out here produces usable data for mine planning. For target depths under about 150 m, exploration drilling stays cheaper, because shot holes must be drilled below the weathered layer.
The Relationship Between Geological Structures and Dolerite Intrusions in the Witbank Highveld Coalfield, South Africa
2008
Structural study of dolerite dykes and sills at four collieries south of the Ogies Dyke, linking intrusion geometry to mining conditions and coal quality. For mine geologists.
What this report foundDolerite intrusion mechanisms and their metamorphic effect on coal were examined across four collieries in the south eastern Witbank Coalfield.
R1500,00
Dolerite intrusion mechanisms and their metamorphic effect on coal were examined across four collieries in the south eastern Witbank Coalfield. In decreasing order of importance, intrusions cut safety by raising the risk of roof, pillar and floor failure, raise mining costs, reduce saleable tonnage, and increase waste generation and environmental risk.
Underground Trials of Seismic-counter and Goafing Characteristics in Pillar Extraction
2003
Underground trials at South African collieries of a seismic early warning instrument first developed for an Australian longwall, with analysis of how roof layers fail during pillar extraction.
What this report foundA stand-alone device was built that detects micro-seismicity within 100 m of the roof and raises an alarm when preset thresholds are exceeded, giving early...
R1500,00
A stand-alone device was built that detects micro-seismicity within 100 m of the roof and raises an alarm when preset thresholds are exceeded, giving early warning of goafing. Input parameters proved not to vary with geotechnical setting. Man-made noise triggering false alarms remained the main obstacle, addressed by signal conditioning and sensor placement.
Update of Coal Pillar Data Base, Strength Formula and Probability of Failure for South African Coal Mining
2012
Reviews how the failed and intact pillar record, tributary area loading and the safety factor concept have developed since 1960, for rock engineers and regulators.
What this report foundFailures continued after the safety factor approach was adopted, in pillars created both before and after it, so the record of failed workings has kept growing...
R1500,00
Failures continued after the safety factor approach was adopted, in pillars created both before and after it, so the record of failed workings has kept growing since the original 27 cases. The database was updated and re-analysed to revise the strength formula and to set out the probability of failure associated with pillar designs.
Verification of the New Coal Pillar Strength Formula and Investigations Into the Prediction of Pillar Life in Witbank and Highveld Coalfields
2004
Covers pillar load and strength estimation, the limits of tributary area theory, and the extraction gains available from revised strength formulae, for rock engineers designing bord and pillar workings.
What this report foundLaboratory testing showed coal specimen strength rising linearly with width to height ratio and falling exponentially with specimen size, the size effect...
R1500,00
Laboratory testing showed coal specimen strength rising linearly with width to height ratio and falling exponentially with specimen size, the size effect becoming insignificant beyond about 2 m diameter. The slope of that relationship was the same for coals from different mines, while the intercept varied with specimen size.