DIAMOND CORE DRILLING RIGS
Diamond core drilling rigs utilize a diamond-impregnated drill bit attached to the end of hollow drill rods to cut a cylindrical core of solid rock. Through the holes in the bits water comes to the cutting face. This provides lubrication, cooling and removal of drill cuttings from the hole.
Diamond core drilling is much slower then reverse circulation drilling method due to hardness of rocks which are being drilled. Core drilling is performed mainly in the solid rocks, and usually at depths of 1,200 to 1,800 meters.