What is a down the hole drill?

A “down the hole” (DTH) drill is a piece of drilling equipment used in mining, construction, and exploration activities. It is specifically designed for drilling large-diameter holes in hard rock formations.

How much pushdown does a hammer drill need?

When DTH (down the hole) hammer drilling, since the air compressor is providing much of the force for each hammer blow, much less pushdown is required. A general rule of thumb is 500 lbs per inch of bit diameter. RPM: In drilling terms, it is the revolutions per minute of the drill string provided by the drill rig’s rotation head.

How was a hole drilled?

This system could not guarantee a finished hole size and only pure vertical holes could be drilled as the system basically relied on gravity. Debris from the hole was baled out using a baling tube with a clack valve, which was periodically dropped on a winch to capture the slurry, which was then brought to the top of the hole to be discharged.

How much weight does a rotary bit drill need?

Mud rotary bits drilling in soft formations are run with lower weight (1,100 to 3,000 lbs per inch of bit diameter) than harder formations which can require up to 5,000 lbs per inch of bit diameter. As more weight/drill pipe is added to the drill string, less pushdown is required from the rig.

What is a blasthole rig & Drill?

Blasthole rigs and drills don’t need much explanation. They’re used for drilling a hole into the surface of the rock, packing the hole with explosives and then detonating those explosives in the blasthole to break up rock and hard minerals to make it easier to remove.

How much pullback capacity should a drill rig lose?

Therefore, a safety factor of 40 to 50 percent pullback capacity loss should be accounted for. For example, a drill rig such as the K60 having 22,000 lbs of pullback at 50 percent capacity will retract 137 drill rods, 10 ft long, weighing 80 lbs each (in other words, a drill string of 1,370 ft).