Types of Drilling Patterns for Underground Mining


The mining lifecycle begins with exploration then goes on to production and finally processing. Even so, these three primary processes of mining somewhat overlap. After the discovery of minerals through exploration, you embark on surface or underground mining. Surface mining entails all methods of mining minerals found in the earth’s surface. It is classified as open-pit mining and includes quarrying, dredging, contour mining, and strip mining.

Underground mining handled by drilling tools for construction is the most common mining type. The construction element in this option is because the point of access is essentially a controlled cave. Its construction entails several calculations to guarantee the safety of the miners and ensure you can effectively get the underground minerals to the surface.  The primary techniques used for underground mining include diamond core, reverse circulation, and rotary air drilling. Diamond core drilling is the popular choice because it is highly accurate, and produces minimal debris, dust, and noise. The following are the drilling patterns that can apply to your mining process.

Pyramid and Wedge Cuts

These are the most commonly used drill patterns for hard, uniform, and deeply-embedded rocks. In a pyramid cut, holes are drilled at the corners of a square to meet at the back edge, thus forming a pyramid-like shape. The depth of your pyramid cut will be restricted to about 50-60% of the drift’s width. Wedge cuts, on the other hand, have holes inclined towards the center and meeting towards the back of your construction.

Drag Cuts

These have widths of 1.8-2.4m. Drag cuts are usually used for small drifts that will not need a lot of clearance for mining. Holes are drilled at angles to the cleavages such that strata break along cleavage planes. As such, you will not need the large reamed holes as you do in other techniques to generate an initial cut into an excavation. With the drag cut, however, you might need to make frequent changes during mining. This makes it unsuited for large excavations.

underground mining

Burn Cuts

Here, parallel holes will be cut at right angles in clusters. Some of the holes of larger diameters will be left uncharged so that they generate relief to the charged holes that have heavy explosive concentrations. With burn cuts, you have significantly reduced drilling times, and the blasted material will not be projected too far from your mining site. These cuts are, however, only suitable for homogenous, hard, and brittle mining grounds that will break evenly.

Coromant Cuts

These are relatively new parallel cuts. In principle, the cuts comprise unloaded slots and six outer holes in carefully calculated locations. A special drill jig will be used for the outer holes to guarantee that they are precisely dug. The standard coromant cut that includes six holes can be used on most rock types since it gives the dislodged rock sufficient expansion room.

Cutting costs is an essential element in maximizing profits. Even so, the success of mining is hinged on the drill bits you will use to make the above cuts. As such, you should not cut costs in inferior cutting tools and hamper your operation.

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