Inhaltsangabe
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 edition. Excerpt: ...as much core as possible. To some extent this is evidently the principal object in boring, but as already pointed out, it is sometimes a matter that may be entirely neglected. The percentage of core that it may be possible to save depends upon the nature of the ground and the diameter of the drill rods. With the ordinary sizes of rods it is almost impossible to save much core in very broken or soft ground. When the core is broken up the fragments in the core-barrel quickly grind each other to powder, especially in such rock as shale. When it is essential to save all the core, as for instance when it is believed that the borehole is approaching the reefs, the only thing to be done, if the ground is very soft, is to drill very slowly, and constantly lift the rods, so that the core has not time to be ground away. In these cases also the bore-meal should be carefully settled and collected by the core-watcher, as it comes from the borehole, and can then be examined and assayed. Tram. Intt. M.M., vol. V, p. 86. When the whole of the boring has to be done in soft ground, as in boring for coal, the ordinary sizes of diamond drill are unsuitable, and probably the best kind of drill to use is the " Calix," which will take out an 8 in. core. The smallest percentage of core saved has been 5 per cent. in shale, in borehole No. 5, but this was probably due to carelessness. The largest percentage has been 98-7 also in shale, but this also is unusually good. When boring in good ground solid pieces of core from 6 to 10 ft. long are not unfrequently obtained. The ordinary Witwatersrand conglomerates generally give excellent core. The average amount of core saved over 9,514 ft. of boring in solid formation was 78 38 per cent. In the tabular...
Die Inhaltsangabe kann sich auf eine andere Ausgabe dieses Titels beziehen.
Reseña del editor
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 edition. Excerpt: ...as much core as possible. To some extent this is evidently the principal object in boring, but as already pointed out, it is sometimes a matter that may be entirely neglected. The percentage of core that it may be possible to save depends upon the nature of the ground and the diameter of the drill rods. With the ordinary sizes of rods it is almost impossible to save much core in very broken or soft ground. When the core is broken up the fragments in the core-barrel quickly grind each other to powder, especially in such rock as shale. When it is essential to save all the core, as for instance when it is believed that the borehole is approaching the reefs, the only thing to be done, if the ground is very soft, is to drill very slowly, and constantly lift the rods, so that the core has not time to be ground away. In these cases also the bore-meal should be carefully settled and collected by the core-watcher, as it comes from the borehole, and can then be examined and assayed. Tram. Intt. M.M., vol. V, p. 86. When the whole of the boring has to be done in soft ground, as in boring for coal, the ordinary sizes of diamond drill are unsuitable, and probably the best kind of drill to use is the " Calix," which will take out an 8 in. core. The smallest percentage of core saved has been 5 per cent. in shale, in borehole No. 5, but this was probably due to carelessness. The largest percentage has been 98-7 also in shale, but this also is unusually good. When boring in good ground solid pieces of core from 6 to 10 ft. long are not unfrequently obtained. The ordinary Witwatersrand conglomerates generally give excellent core. The average amount of core saved over 9,514 ft. of boring in solid formation was 78 38 per cent. In the tabular...
„Über diesen Titel“ kann sich auf eine andere Ausgabe dieses Titels beziehen.
