Thursday, February 14, 2008

Gold mining

Gold mining consists of the processes and techniques employed in the removal of gold from the ground. There are several techniques by which gold may be extracted from earth and rock

Gold in goldpan, Alaska

Gold panning is the easiest technique for searching for gold, but is not commercially viable for extracting gold from large deposits, except where labor costs are very low and/or gold traces are very substantial. It is often marketed as a tourist attraction on former goldfields. Before production methods can be used, a new source must be identified and panning is a good way to identify placer gold deposits so that they may be evaluated for commercial viability.

Metal detecting

A new small scale technique using metal detectors for finding gold. Using a piece of electronic equipment, called a metal detector, a person may walk around area systematically scanning below the surface. If the meter gives a positive reading a quantity of gold may be present up to a meter below the surface being scanned at the time. This technique is very easy to operate, highly mobile, and very popular among gold diggers.

Sluicing

Using a sluice box to extract gold from placer deposits has been a common practice in prospecting and small-scale mining throughout history to the modern day. A sluice box is essentially a man-made channel with riffles set in the bottom. The riffles are designed to create dead zones in the current to allow gold to drop out of suspension. The box is placed in the stream to catch water-flow and gold bearing material is placed at the top of the box. The material is carried by water through the box where gold and other heavy material settles out behind the riffles. Lighter material flows out of the box as tailings.

Larger commercial placer mining operations employ screening plants or trommels to remove the larger alluvial materials such as boulders and gravel before concentrating in a sluice box or jig plant.

No comments: