Borehole Mining

Borehole mining (BHM) is a remote controlled method of underground mining used to mine a broad range of natural resources and industrial materials such as uranium, iron ore, quartz sand, gravel, coal, gold, diamonds, and amber. A borehole tool comprised of two pipes—one that delivers a stream of high pressure water, and another that delivers slurry back up to the surface—is used. Borehole mining technology is also used in exploration, oil, gas and water stimulation, in-situ leaching, and in the construction of underground storage and drainage systems.^[1]

[edit] Process

Borehole mining is a fairly new unobtrusive mining approach developed in the 20th century.^[2] The process begins with lowering a borehole mining tool mounted on a drill rig tower into a borehole. The drill rig tower provides the tool with the ability to rotate and move up and down along the axis of the borehole.^[3] As the borehole mining tool is lowered to a required depth inside the hole, high-pressure water is pumped down and emerges as a high-powered jet stream through a hydromonitor nozzle located near the tool’s bottom. The jet stream is so powerful it actually cuts and breaks apart rock mass. Water is added to the broken rock, forming a slurry.

Another portion of water comes up through another part of the tool called a hydro elevator, which is comprised of a jet pump and educator. Together, these components produce a vacuum that sucks and then pumps the slurry back up towards the surface. The slurry of rock debris and water is then separated in a storage tank. Water is then pumped back down to close off the tool’s water system.^[4]

As a process, borehole mining provides many advantages as compared to conventional mining practices. Areas considered too dangerous to mine using other methods can be accessed with borehole mining equipment. As a process, borehole mining is also extremely mobile and equipment can be transported from site to site. The technique can be implemented on an open-pit mine floor, land surface, underground mine, or on a floating platform or vessel through boreholes that have been predrilled.^[5] The cost of borehole mining in comparison to other underground methods is less expensive as it eliminates the need to remove overburden, construct shafts and tunnels, and provide ventilation, de-watering, and transportation of workers underground.^[6] The greatest benefit of borehole mining, however, is that it is less invasive on the environment than other methods.

[edit] References

1. ↑ Borehole Mining. Answers.com, 2008-09-29.
2. ↑ Dimitrijevic, Bojan; Pinka, Jan; Mitrovic, Vladimir. Selection of technological parameters in borehole mining production by technical deep drilling and hydroexploitation. Acta Montanistica Slovaca, 2008-09-29.
3. ↑ Dimitrijevic, Bojan; Pinka, Jan; Mitrovic, Vladimir. Selection of technological parameters in borehole mining production by technical deep drilling and hydroexploitation. Acta Montanistica Slovaca, 2008-09-29.
4. ↑ Dimitrijevic, Bojan; Pinka, Jan; Mitrovic, Vladimir. Selection of technological parameters in borehole mining production by technical deep drilling and hydroexploitation. Acta Montanistica Slovaca, 2008-09-29.
5. ↑ Borehole Mining. Answers.com, 2008-09-29.
6. ↑ Dimitrijevic, Bojan; Pinka, Jan; Mitrovic, Vladimir. Selection of technological parameters in borehole mining production by technical deep drilling and hydroexploitation. Acta Montanistica Slovaca, 2008-09-29.