Exploration diamond drilling

Exploration diamond drilling is used in the mining industry to probe the contents of known ore deposits and potential sites. By withdrawing a small diameter core of rock from the orebody, geologists can analyse the core by chemical assay and conduct petrologic, structural and mineralogical studies of the rock.

History

Early diamond drilling opened up many new areas for mineral mining, and was related to a boom in mineral exploration in remote locations. Before the invention of the portable diamond drill, most mineral prospecting was limited to finding outcrops at the surface and hand digging.

Diamond drilling

Exploration diamond drilling differs from other geological drilling (see Drilling rig) in that a solid core is extracted from depth, for examination on the surface. The key technology of the diamond drill is the actual diamond bit itself. It is composed of industrial diamonds set into a soft metallic matrix. As shown in the figure, the diamonds are scattered throughout the matrix, and the action relies on the matrix to slowly wear during the drilling, so as to expose more diamonds. The bit is mounted onto a drill stem, which is connected to a rotary drill. Water is injected into the drill pipe, so as to wash out the rock cuttings produced by the bit and also to reduce the heat produced due to friction which causes less wear and tear of the bits. An actual diamond bit is a complex affair, usually designed for a specific rock type, with many channels for washing.