May 24 2014
Panning is a simple mining method that separates particles of high specific gravity, such as gold, from gravels or soil by washing in a pan. Pans of various sizes have been developed over the years. A typical pan is a rugged, circular metal dish with a flat bottom, and sides that are inclined at about 45°.
The inner surface of a pan is smooth and free from rust and grease. The size of the pan ranges from 10 to 17in. with 14in. pans being widely used.
During the panning process, the pan is half-filled with gravel, rocks, and soil, that are collected from places with slow current flow. The pan is then submerged in water to wet the mixture thoroughly.
The mixture is then stirred and lumps of clay are broken up, from which large stones are collected. The pan, which is still inside water, is provided with gyratory motion and shaking.
As a result, heavy particles settle at the bottom, bringing up the lighter materials to the surface. The pan is tilted at intervals to wash off the light surface materials.
This process is continued until heavy black sands, such as magnetite, pyrite, and ilmenite, and gold remain. The material is then dried, and gold is separated.
Pans used for panning are made of both metal and high-quality plastic. Heavy gauge steel and Russian iron pans are commonly used. Steel pans are stronger and heavier than plastic pans. Some of them are made of lightweight alloys, for structural stability.
In addition, plastic gold pans, which resist corrosion and acid, are used. Most of the plastic pans are designed with molded riffles in one side of the pan.
References