Mining in Manitoba
Methods of Prospecting
Diamond Drilling
The primary function of the diamond drill is to secure a core of the earth's crust. By analyzing the rock core, the presence of mineralized zones can be revealed and their market value determined.
The size of the drill core varies with the size of machine used, hole depths and material being drilled.The common sizes of drill core are:
| A core diameter 27.0 mm |
| B core diameter 36.5 mm |
| N core diameter 47.6 mm |
The diamond drill consists of a power unit rotating a tubular bit which has a diamond cutting edge.
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The bit, and attached core barrel are rotated at speed under controlled pressure, by means of hollow, flush-joint rods, made of steel, through which water is pumped to cool the bit, and remove the rock cuttings. With the advance of the bit, a cylinderical core of rock passes up into the core barrel where it is held by a core lifter or other means. The circulating water raises the sludge or cutting to the surface outside the rods. The rods are withdrawn at intervals of 1.5-3.0 m, and the core and cuttings reveal a accurate record of the various formations through which the bit has passed.
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The larger drills have recovered cores up to 100 mm in diameter from depths of more than 4,500 metres.