How to Approach the Undermining of Surface Structures With Emphasis on Wetlands
by D. S. Minney | October 2015
R1500,00
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A diatom based index for pans impacted by acid mine drainage
2021
Wet and dry season sampling of epiphytic diatoms from reed, salt and grass pans on the Mpumalanga Highveld, validating a biomonitoring index for mine affected depressional wetlands.
What this report foundLevel of acid mine drainage disturbance explained more of the variation in diatom communities than any other factor, with pan type second and season not...
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Level of acid mine drainage disturbance explained more of the variation in diatom communities than any other factor, with pan type second and season not significant. Sulphate and calcium concentrations and sulphate to chloride ratios were higher in disturbed pans of every type. Pan type specific indices were tested against established riverine indices.
Verification of the New Coal Pillar Strength Formula and Investigations Into the Prediction of Pillar Life in Witbank and Highveld Coalfields
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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...
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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.
Can old bord-and-pillar workings be mapped from surface?
2016
Desktop review updating two earlier assessments, weighing borehole scanning, robots and unmanned aerial platforms as routes to locating old workings ahead of opencast drilling and blasting.
What this report foundNo surface geophysical method can map individual bords and pillars at the depths typical of the Witbank coalfield, a limit the review attributed to physics...
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No surface geophysical method can map individual bords and pillars at the depths typical of the Witbank coalfield, a limit the review attributed to physics rather than to technology, since the targets are small relative to their depth and conductive layers often lie above the seam. Borehole laser scanning remains the workable option, with sonar suited to flooded workings.