Coaltech Research Association

Determine Possible Means to Conduct Large Scale Frictional Ignitions Tests, and the Value of These to Coaltech

T F Ngobeni

A scoping exercise based on technical enquiries to mine safety organisations and discussions at an international conference, aimed at rock engineers and safety practitioners weighing test facility investment.

What this report found

No operating full scale frictional ignition test facility was found anywhere in the world, and building one was judged expensive, impractical and unlikely to justify its cost against laboratory scale testing. Effort should instead go to small scale laboratory equipment using South African rocks, and to expanding geological data such as silica distribution and petrographic analysis.

R1500,00

Description

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The impact of cattle grazing on rehabilitated land

Two annual surveys of species composition, biomass and soil sampling inside and outside fenced plots on rehabilitated pasture at an opencast colliery near Ogies, with benchmark sites for comparison.

What this report foundGrazing pressure on the rehabilitated block ran at roughly three times the estimated carrying capacity.

R1500,00

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What this report found

Grazing pressure on the rehabilitated block ran at roughly three times the estimated carrying capacity. The sward was dominated by low quality grasses with a high proportion of bare ground and a raised erosion risk. Fenced exclosures over one year changed the abundance of a few species, but the vegetation showed no clear direction of recovery.

Spontaneous Combustion of Coal and Coal-shales

2018

Laboratory testing of samples from South African collieries using two Wits self-heating indices alongside proximate and ultimate analysis, for ventilation and safety engineers assessing burning shale risk.

What this report foundTesting of 28 coal and coal-shale samples showed the coals to be more liable to spontaneous combustion than the shales, though reactive coal-shales still...

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What this report found

Testing of 28 coal and coal-shale samples showed the coals to be more liable to spontaneous combustion than the shales, though reactive coal-shales still self-heat and pyrite in them speeds the process. Higher carbon, moisture, hydrogen, volatile matter and nitrogen with lower ash all raised proneness to self-heating, so proximate and ultimate analysis can serve as a screening tool.

Verification of the New Coal Pillar Strength Formula and Investigations Into the Prediction of Pillar Life in Witbank and Highveld Coalfields

I Canbulat

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...

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I Canbulat

What this report found

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.

Freddie Hunter

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