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1978年,美国Monterey公司1号矿山采用装有Ingersoll-Rand RBH-8ER20天井钻头的Ingersoll-Rand RBM211天井钻机钻进,建成直径6.17米、深93米的竖井两个,每天钻进速度大约6.7米,据称是创造了世界
In 1978, the No. 1 Monterey Mine in the United States was drilled with an Ingersoll-Rand RBM211 pit drill equipped with Ingersoll-Rand RBH-8ER20 pit drills to build two shafts of 6.17 meters in diameter and 93 meters in depth. The drilling rate per day was about 6.7 meters , Is said to have created the world