Monday, 28 June 2010
Thursday, 24 June 2010
Bewick Horizons
"Acclaimed as an observant and accurate naturalist, an artist of skill, originality and humour, Bewick also found that the more facts he learned, the more he was intrigued by the numinous, the flickering promise beyond the horizon."
'Nature's Engraver' by Jenny Uglow (p313)
'Nature's Engraver' by Jenny Uglow (p313)
Thursday, 17 June 2010
Longwall
Bord and pillar mining is not particularly suitable for mining coal at very great depths, because of the size of pillars that have to be left. The main alternative is longwall mining, which has been practised for many years in the deep European mines, particularly in the United Kingdom and West Germany. Two parallel roadways (called 'gates') are driven through the coal seam normally between 200 and 300 metres apart. This distance effectively determines the length of the working face. The two roadways are joined by a drivage in the seam at right angles to them and this forms the working face (or longwall). The roof at the working face is normally supported by hydraulically powered roof supports.
from http://www.competition-commission.org.uk/rep_pub/reports/1982/fulltext/160c02.pdf
from http://www.competition-commission.org.uk/rep_pub/reports/1982/fulltext/160c02.pdf
Pitmatic Notes
More notes from 'Pitmatic' by Bill Griffiths:
p86 There are three grades of coal: lignite, bituminous and anthracite. The Great North East Coalfield is almost exclusively of bituminous coals. 'Bituminous coal - coloured brown to black, is mostly used for industrial purposes'.
p93 'As the seams vary within a coalfield, and can have different local names' the Coal Board assigned letter references to each seam. The start of the alphabet is the shallowest and each subsequent letter gets deeper. So Hutton (L) is near to the surface and Brockwell (S) is deep down.
p95 'Coal seams occur in sedimentary layers, approximate to the ancient land surface on which they were laid down. Horizontal once, they now tilt significantly, being nearer the surface in the north and west of the coalfield, deeper in the east: accordingly the passages in a pit do not proceed on an even plane. With no horizon to compare it with, the incline of a seam and roadway that follows it might not be immediately obvious'.
p102 'As to the extraction of coal, the land-owner has the mineral rights on his property, and could either start mining or issue a lease to someone to do the mining, in return for royalties'.
p86 There are three grades of coal: lignite, bituminous and anthracite. The Great North East Coalfield is almost exclusively of bituminous coals. 'Bituminous coal - coloured brown to black, is mostly used for industrial purposes'.
p93 'As the seams vary within a coalfield, and can have different local names' the Coal Board assigned letter references to each seam. The start of the alphabet is the shallowest and each subsequent letter gets deeper. So Hutton (L) is near to the surface and Brockwell (S) is deep down.
p95 'Coal seams occur in sedimentary layers, approximate to the ancient land surface on which they were laid down. Horizontal once, they now tilt significantly, being nearer the surface in the north and west of the coalfield, deeper in the east: accordingly the passages in a pit do not proceed on an even plane. With no horizon to compare it with, the incline of a seam and roadway that follows it might not be immediately obvious'.
p102 'As to the extraction of coal, the land-owner has the mineral rights on his property, and could either start mining or issue a lease to someone to do the mining, in return for royalties'.
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