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苏联砂矿的勘探主要采用钢绳冲击钻进,孔径在219毫米以内。但是,根据苏联中央地质勘探科学研究所的研究表明,不必作验证的评估砂金矿的钻孔,其最小的孔径不得小于500毫米。从砂矿成矿条件特殊和矿藏分散与聚集的特点看,为了可靠地评估矿层,需要体积大的矿样和取样精细的钻探工艺。砂矿钻进的最主要特点是必须用跟管或超前套管保护孔壁的某一段或松散砂矿层的
The exploration of the Soviet placer mainly uses steel rope impact drilling, the aperture is within 219 millimeters. However, according to a study conducted by the Soviet Institute of Central Geological Exploration, it is not necessary to validate the drilling of placer gold, and its minimum aperture must not be less than 500 mm. In view of the special mineralization conditions of sand and the dispersion and accumulation of the mineral deposits, large-sized ore samples and fine sampling drilling processes are needed in order to evaluate the ore layers reliably. The most important feature of sand mining is the need to follow the tube or lead casing to protect a certain section of the hole wall or loose sand layer