| 摘要 |
<p>1,091,844. Hydraulic mining. GLOWNY INSTYTUT GORNICTWA. May 25, 1965 [May 25, 1964], No. 22251/65. Heading E1F. Coal is mined in thin layers from a longwall face by a small diameter, high pressure water jet directed parallel to or an angle of up to 10‹ to the face, oscillated vertically across the face and at the same time moved horizontally along the face.</p> |
