Along with knowing how to find gold, it is also very important to know the techniques to extract the gold efficiently from the gravels or host rock that it is mixed with. Extracting gold is required in both small-scale and large-scale operations where the prospectors may need to purchase more advanced equipment. To separate extra fine gold from other minerals may prove to be a difficult task but these small, fine particles of gold can total up to huge amounts so it is advantageous for the prospectors to make sure they aren’t missing it.
The best method to extract gold is some type of gravity separation, which actually utilizes the physical properties of gold i.e. the differences in the densities, specific gravity, size and shape of gold and the other minerals. One of the most basic and simple processes to extract gold is gold panning. Some of the gravel is collected from the location of the placer deposits and is scooped into a pan. Once in the pan, the gravel is agitated gently in water until the gold sinks to the bottom of the pan.
The gold pan is a must-have prospecting tool, but it isn’t going to be enough for larger mining operations. There is specialized equipment that will capture large amounts of fine gold much more quickly and efficiently.
Using Shaker Tables for Fine Gold
For large mining operations, expensive gold separation methods like shaker tables (also called Miller Tables) can prove to be advantageous. It basically looks like a table that vibrates back and forth while separating the gold from the other minerals.
For a gold shaker table to work efficiently, the user needs to make sure that both ends of the tables are tilted in two dimensions. The black sand concentrates or crushed ore is then fed onto the table and water is sprayed along the top edge of the table.
This is basically the water access point where clean water is filled and should be sprayed enough to allow the vibrations of the table to provide the particles with partial buoyancy. This in turn helps with the separation process. With the help of a vibrator, the table begins to have a reciprocal movement along the axis.
The surface of the gold shaker table is fitted with small tapered stripes called riffles or grooves to obtain a turbulent flow of water. This helps the lighter particles to move from one riffle to the other, whereas the heavier particles move along the direction of the riffles. Since the riffles are downwards in elevation, the heavier particles, including gold is discharged at the end of the table. The lighter particles that are trapped on the riffle are fed to a collection stream at the end of the riffle.
Adjustment and Setup of a Shaker Table
There are several adjustments that need to be dealt with before using the shaker table. The person setting up the table needs to make sure that the adjustment is such that the slope is enough and the water flow is enough. If the table is placed to steeply or the water sprayed is too high, then the heavier particles will be swept over to the riffles.
Other important factors are the particles characteristics, the table speed, table inclination, stroke length and the wash water volume. Riffles height and their patterns are designed depending on the desired duty expected. These adjustments are set according to the operating conditions needed by the worker and the kind of feed fed to the table.
Gold shaker table proves to be useful equipment in gold prospecting, since it requires no reagents and has high separation efficiency and is also environmentally friendly unlike mercury amalgamation. For many commercial mining operations, these are the final tool used for fine gold separation.
Some of the larger shaker tables probably too expensive for the casual prospector, but now there are smaller versions that are much less expensive and actually work very well when processing smaller quantities of material.
Next: Classify Gravels to Retain More Fine Gold