单词 | rotary blasthole drilling |
释义 | rotary blasthole drilling [`rōd·ǝ·rē `blast´hōl ´dril·iŋ] MINING ENGINEERING A term applied to two types of drilling: in quarrying and open pit mining it implies rotary drilling with roller-type bits, using compressed air for cuttings removal, either conventional rotary table drive or hydraulic motor to produce rotation, with hydraulic or wire-line mechanisms to add part of the weight of the drill to the weight of the tools to increase bit pressure; and in underground mining and sometimes aboveground, it implies the drilling of small-diameter blastholes with a diamond drill, using either coring or noncoring diamond bits. |
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