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The Desert Fox is an easy machine to set up and
use and it can be fine tuned to specific ores. Because no two
placer ores will work exactly the same in the machine there
are a few basic things you should understand about how the
Fox separates gold from sand.
The Desert Fox uses specific gravity differences between
the gold and sand to allow for mechanical separation of the two
materials. When grains of gold, black sand and brown sand
are compared, it will be noted that if the weights of the grains
are equal the size is greatly different. Likewise, if the grains
are classified so that they are uniform in size, then the weights
are very different. It is this size to weight ratio that allows the
FOX to separate the gold from the sand.
Always be suspicious of minerals that won't separate
from the gold in your panning machine. Remember that any-
thing more than 10 times the weight of water is worth some-
thing!
Some black sands carry platinum and palladium group
metals. Platinum occurs as a gray metal which is as heavy as
gold and is worth more! The Fox cannot separate platinum from
gold.
The wheel is made of a slippery material which allows
gold or other heavies to slide in the bottom of the riffles. This
effect is enhanced by the water and motion of the wheel.
Gold is usually nearly pure in nature and being a metal
has a natural affinity for oil. Oil attaches to the surface of the
gold and will cause small pieces of gold to float on water due
to the surface tension of the water. You can counter the ef-
fects of oil on your gold by using a wetting agent to stop flota-
tion of oily gold. Wetting agents such as Jet Dry Rinsing Agent
are available in most grocery stores in the soap department.
We do not recommend regular soaps or detergents because
of sudsing.
Water settings and wheel pitch interact and since no
two placer sands run the same in the machine you will have to
work both adjustments to find the best running combination for
your machine.
THE VARIABLE SPEED OPTION (If installed)
The variable speed option allows you to slow down the wheel
without slowing down the water pressure from the pump. This
feature is handy when separating properly classified precious
stones like diamonds and saphires. You willhardly notice the
change in wheel speed until you add gravel to the wheel.
You will not need the speed control when panning ordinary
placer gold sand. Use the control in the normal speed setting.
Grain size is also of importance, especially when the
placer material is much larger than the placer gold. The gen-
eral rule is that if you have gold of a specific size range then
your maximum sand grain size should not be more than 5 times
the gold flake size. How is this calculated? Well, let's say your
target gold is in the -100 grain size (1/100 of an inch or smaller)
then your correct starting screen size would be #20. This for-
mula is very easy to remember, just divide the average grain
size of the gold by 5 and you have the screen size!
We recommend a starting screen size for unknown ma-
terials at 1/10" or #10. The mesh size of the screen is gener-
ally given as the particle size (fraction) which will pass through
the screen.
Simply set the wheel up at a convenient angle between
30 and 45 degrees and start it up. Feed in a little ore after the
water is running on the wheel and watch what happens. If the
black sand is getting in the hole make the wheel pitch a little
steeper. If the black sand is way down on the face of the wheel
do the opposite. Always remember this...
You will not lose any gold from this machine because it
is a closed system, If you think you have spilled gold into the
tailings then rerun them. Once you become comfortable with
the machine then you will know when it is OK to dump the
tailings
Can't separate your gold from the black sand? Let's
explore the possible causes... First if you are running straight
black sand in the machine that is probably the problem! De-
concentrate by mixing in an equal volume of brown sand. This
will give the machine a chance to work the material and allow
for some flotation effect on the wheel.
