| 摘要 |
<p>A shaft is sunk through spoil layers, such as sand, dirt, clay, sedimentary deposits, slate, etc., to the coal. A second shaft is drilled from the surface to the coal in proximity to the first shaft, and a small shaped charge is placed down the first shaft and directed toward the termination of the second shaft. A pipeline containing a directive nozzle is then directed down the first shaft with the nozzle oriented toward the second shaft and water and air pumped through it. A line is dropped through the second shaft terminating in a hydraulic elevator, water being pumped down the shaft and up through the hydraulic elevator.</p> |
