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Recovering Gold from Black Sand
As appearing in The Gold Nugget, March 1996
by Charles Hawkins

For as long as you have been prospecting, I am sure most of you have heard the instructions to save your black sand, but why? What do you do with the stuff? After you have panned all the gold you can remove with your gold pan and sniffer bottle (also called snifter or snuffer), what next? The answer is not all that complicated ... save it in 5-gallon buckets. After all, you worked hard to get these concentrates and, best of all, if you found gold, there's sure to be more in your black sand. The next question is, how can I get to that gold?

Gold exists in black sand in two forms, free gold and gold alloy. Free gold can be particles so small that they are almost impossible to see as individual pieces. Gold alloy is gold that is in combination with other minerals that make up the black sand. These two forms of gold are liberated in two ways, mechanical and chemical.

The first important process in recovering your free gold from your black sand is to size or screen your material. Even though the gold is about twice as heavy as the other materials that make up your black sand, it is still nearly impossible to separate the gold, unless the material you are separating it from is of the same physical size.

You can make screens from material found at a hardward store or purchase them from your local prospecting store. The size of the various screens you need is determined by the size of the material you are processing. I use several screens that I have purchased and which are designed to fit the top of a 5-gallon bucket. These are convenient and allow me to save my screened material in separate buckets until I have enough material to process.

I use 12-, 20-, 50-, and 100-mesh screens and have known people to use screens with openings as small as 200 mesh. Remember, the material must be completely dry before screening can be accomplished. The main purpose here is to get the material sized so that the gold and other material in each bucket is the same size.

After you have sized your material in several containers, you are ready to process this material and liberate the gold.

There are several mechanical products that will assist you in the removal of your free gold from your black sand. Each of these machines is unique in its own way. They all share one thing in common, however . . . they use water and specific gravity to remove the gold. This is the same as using your sluice box, highbanker, dredge, or gold pan. Some of the most common machines are as follows.

Mechanical Gold Separators

Mini-Sluice

The Mini-Sluice is a smaller brother of the sluice box you use in the stream. The smaller size allows for a small stream of water, which allows the very small gold to fall out and get trapped in the riffles and carpet of the sluice as the lighter material is carried away by the water flow.

Spiral Gold Systems

The spiral gold pan systems come in several designs but the technology is very similar, with size, capacity, and price the largest variables. Most spiral systems start with a molded plastic pan that is mounted to a motorized unit that turns the pan. The pan is normally tilted at a 45-degree angle and either has water that is sprayed onto the pan or sits in a tub of water. The pan has machined spirals that begin at the outside edge of trhe pan and spiral into its center. Because of the angle and design of the spirals, the lighter material falls out of the spirals prior to reaching the center of the pan and is returned to the bottom edge of the pah where it is eventually washed over its front edge. The weight of the gold causes it to sit low in the spirals and it is carried to the center of the pan where it is recovered.

Concentrator Bowl

The concentrator bowl is a molded plastic bowl that has a tapered cone in the center of the bowl and a water hose connection molded to its outside wall. It looks a lot like a bunt pan used by cooks to bake the cakes that have holes in the middle. As material is added to the bowl, the lighter material is swept to the top of the cone by the water flow and drained away through the center of the cone. The heavier gold remains in the bottom of the bowl.

Chemical Gold Separation

There are several chemical methods of extracting the very last bit of gold from your black sands.

WARNING: ALL CHEMICAL GOLD SEPARATION PROCESSES ARE VERY DANGEROUS IF NOT PERFORMED PROPERLY AND WITH GREAT CARE. Thus we will list the names of some of those processes but will not explain any here:

Seek professional help and instruction before attempting any chemical gold separation process.

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© 1996 Gold Prospectors of the Rockies