Percentage of Extractions of Bituminous Coal With Special Reference to Illinois
Percentage of Extractions of Bituminous Coal With Special Reference to Illinois
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Kooms are 25 feet wide with 20-foot pillars. Rooms are holed through into those of adjoining panels. When the rooms have reached their full lengths, cross-cuts 24 feet wide are driven across the ends of the pillars. In addition to these cross-cuts the pillars are probably slabbed to some extent. The coal is about 9 feet thick, and about iy 2 feet of top coal is left up. No bot- tom coal is left. The barrier pillars are about 100 feet thick. Break-throughs are 21 feet wide. It seems hardly prope...r to speak of this kind of work as the extraction of pillar coal, but it represents a practice which is common in this district. At one of the mines, pillars are drawn, beginning in the middle of a panel, in six rooms at a time; then another group of six pillars is attacked, one pillar being left untouched between the groups. This is simply another method of attempting to get as much coal as possible before being driven out by a fall of the top, and is not an attempt to break the cap rock. Systematic work in the recovery of pillar coal as done at one of the mines is illustrated in Fig.
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To quickly assess the difficulty of the text, read a short excerpt:
Kooms are 25 feet wide with 20-foot pillars. Rooms are holed through into those of adjoining panels. When the rooms have reached their full lengths, cross-cuts 24 feet wide are driven across the ends of the pillars. In addition to these cross-cuts the pillars are probably slabbed to some extent. The coal is about 9 feet thick, and about iy 2 feet of top coal is left up. No bot- tom coal is left. The barrier pillars are about 100 feet thick. Break-throughs are 21 feet wide. It seems hardly prope...r to speak of this kind of work as the extraction of pillar coal, but it represents a practice which is common in this district. At one of the mines, pillars are drawn, beginning in the middle of a panel, in six rooms at a time; then another group of six pillars is attacked, one pillar being left untouched between the groups. This is simply another method of attempting to get as much coal as possible before being driven out by a fall of the top, and is not an attempt to break the cap rock. Systematic work in the recovery of pillar coal as done at one of the mines is illustrated in Fig.
What to read after Percentage of Extractions of Bituminous Coal With Special Reference to Illinois?
You can find similar books in the "Read Also" column, or choose other free books by Clinton Mason Young to read onlineMoreLess
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