Equipment Specs
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Diamond Drill

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Construction Equipment
Mining Equipment

A diamond drill is a rotary type of rock drill that cuts by producing a rotary motion rather than a percussive one. The diamond drill consists of a diamond-clad drill bit attached to a hollow shaft powered by pumped water. The diamond drill is used in the mining industry to drill cylindrical holes into ore 0.8 inches (2 cm) or greater.


[edit] History

Reports suggest that the diamond drill may have been in existence as early as the 1860s. Used for drilling in oiling applications, the drill is a far cry from what it is today and made very little impact in its initial form. The early drill was described as circular and hollow, comprising a thin tube with Brazilian diamonds set on the lower edge of the rod. This diamond drill could drill five feet (1.5 m) deep into the rock before it had to be removed for alteration. The tool had a cutting rate of four feet (1.2 m) per hour, but the drill is said to have produced more.

Rodolphe Leschot invented the diamond drill for practical use in 1863. Leschot’s drill was used for drilling holes for blasting operations and was used in constructing tunnels for Mont Cenis Tunnel. Leschot’s experience as a watchmaker led him to consider diamonds for a drill bit end. The drill consisted of a hollow tube with a set of six diamond stones on the drill bit. The drill was patented in the U.S. that same year. The diamond drill was used in other projects, such as a marble quarry in Vermont.

The drill’s rotary motion was produced by fluid that was pumped through the drill rod. The rotary motion was a special type of drilling that could be used for a variety of purposes and still is today. The use of circulating fluid in rotary machines may have come from a patent issued by Robert Beart in 1844.

In the 1920s, several changes were made to aid the evolvement of the drill. The former six sets of diamond stones were upgraded to eight; as well, a double tube core barrel replaced the single tube core barrel of the drill. The 1940s marked the beginning of several changes to the drill bit. Borts were positioned in the sintered matrix, a change that is considered the norm today. The amount of diamonds used has also increased to suit the application.

The way diamond drills were used has also changed. Initially they were used for drilling holes in mining applications to recover coal. While they are still used in blasthole mining operations today, they are also used for commercial oil drilling and even for general purposes.[1]

[edit] Features

[edit] Drill Bit

This is the sharp, cylindrical steel tip of the drill that penetrates the rock in a rotary motion. Some drills contain tungsten carbide, but this type of drill comprises of a set of diamonds.

[edit] Drill Stem

The drill stem is the long frame of that contains the drill bit at the end of the shaft and houses the drill rod.

[edit] Drill Rod

This is the hollow component that connects the drive and the motor of the rig to the bit. Pumped water makes its way through the rod to produce the rotary motion.

[edit] How it Works

Before a diamond drill is employed, surface sampling is undertaken in order to determine the quantity of ore deposit the mine contains. Once this is ascertained, the diamond drill uses its rotary motion to make abrasions into the ore and drill hole into the rock. The drill, as opposed to percussive drills, grinds through the rock at a rapid rate, a task made possible because the cylindrical bit contains one of the hardest natural substances on earth—diamonds.

The size of the diamond drill varies with the machine used, the depth of the hole, and the material being drilled. Drills have an average of four different core diameter sizes:

  • A: a core diameter of 1.1 inches (27 mm) and a hole diameter of 1.9 inches (48 mm)
  • B: a core diameter of 1.4 inches (36.5 mm) and a hole diameter of 2.4 inches (60 mm)
  • N: a core diameter of 1.9 inches (47.6 mm) and a hole diameter of 2.9 inches (75.7 mm)
  • H: a core diameter of 2.5 inches (63.5 mm) and a hole diameter of 3.7 inches (96 mm)[2]

As the drill grinds away rock material to produce a hole, water is pumped through the rod to wash away the debris.

Diamond drills are powered by hydraulics and use high torque to chip away fragments of rock to produce holes. Diamond drills are usually large in size and are mounted on a mast above the hole.

[edit] Types

Other types of drills used for mining processes can be divided into two different types: rotary and percussive drills.

[edit] Common Manufacturers

[edit] References

  1. Diamond. Petroleum History. 2008-09-24.
  2. Whyte, John and Cumming, John. Mining Explained. Northern Miner: Don Mills: 2004.