Gold Methods

Tools of the Trade

This page is devoted to the various tools used to extract placer gold in the field and the methods for final separation of the yellow stuff from the heavy black sands usually associated with gold.

Panning

Black Sand

Drywashers

Many miners think drywashers are only for use in the desert. The truth is they are useful any place where the material is very dry. Since drywashers are not quite as efficient as devices that use water for separation, wet methods should be used if possible. The recovery rate of a drywasher decreases dramatically as the moisture content of the material increases so make sure the material you are working is very dry. You can dry the material somewhat by either spreading it out on a tarp to dry (it helps if you walk on it now and then to break it up) or you can run it through the drywasher repeatedly until it is dry.

Drywashers come in two basic "flavors". The one pictured at left is a small bellows operated drywasher (also known as a "puffer"). This design has been around for many years and may be hand cranked like this one or may be electric or gas powered (the one in the photo has been converted to electric since this picture was taken). The newer type picrured above uses a gas powered blower and a device to cause a high frequency vibration of the riffle tray. Some of the larger drywashers of this type incorporate an exhaust heater in the blower to help dry the material. The riffles in both types are different than a sluice box as they point upstream instead of downstream.The bottom of the riffle tray in both types is cloth to allow air from the blower or bellows to blow up through the material. It is this air flow along with vibration that separates the heavy concentrates from the rest of the material. Drywashers are often seen in the hydraulic mines in the Sierras because there usually isn't any water available for wet concentration methods.

The VacPac

Everyone I know who owns one of these gadgets loves them. All they are is a gas powered vacuum cleaner using a five gallon bucket. They are lightweight, easy to transport and will run most all day on a pint or two of gas. It is next to impossible to thoroughly clean bedrock with a whisk broom and dustpan but crank up one of these babies and you will leave the surface squeaky clean. VacPacs are a great help in moss mining, crevice cleaning and any other hard to get to or hard to clean place. They can use all ShopVac accessories so replacement hoses and other attachments are readily available.

Some thoughts on VacPac use
It really helps if you can keep the VacPac lower than the area you are cleaning. It doesn't quite have the power to move all the rocks that can fit in the hose uphill. As a matter of fact, things go much faster if you toss all the larger rocks out of the way and just suck up pebbles. If you can't keep the unit below where you are working, lift the hose up above the bucket to let it clear every so often. Don't use the crevice tool unless you have to. The air velocity is higher at the tip but lower in the hose so clogs are more likely to occur when the crevice tool is attached. If the hose does clog, just raise the hose and bang on it with whatever is handy.

Because the VacPac only collects but doesn't concentrate material, you may want to have a sluice box or drywasher close by to process the stuff. I use the small drywasher pictured above in the dry diggings.

I usually use my VacPac in dry conditions but I have been told that when used for damp material, the inside of the hose tends to clog up with caked mud. A spare hose comes in handy at such times. Speaking of spares, keep a spare spark plug (and wrench) and an air filter nearby just in case.

Here's an idea I thought of while searching every nook and cranny of my truck for a wrench to change a fouled spark plug in my drywasher blower. I thought if I couldn't find the wrench, I could hook the drywasher hose to the VacPac outlet. Then I thought of building a small, lightweight drywasher that would be powered by the VacPac. It would be easy to change from vacuuming to drywashing and vice-versa. This would be a portable, lean, mean gold getting machine. If anyone has done that please let me know.

The one complaint I have is under just the right conditions, these gizmos generate a lot of static electricity. I have given some thought to wrapping a wire around the hose near the end and grounding the wire. Unfortunately, I only remember this idea when I am up in the digs and actually getting zapped so I haven't tried it yet.

Gold Vacuums aren't all that hard to build and you can save a lot of money by doing it yourself.

Black Sand Separators

What do you do with all the black sand you've saved over the summer? You are saving it, right? Spiral wheels and the Blue Bowl along with the separators on the plans page will help you deal with it without a lot of tedious panning. Processing your black sand over the winter is a great way to keep your gold fever under control until the weather warms up.

Spiral Wheels

Why Use A Gold Wheel?
How many of you have attended a gold show and watched with fascination as gravel is fed into a spiral gold wheel and the gold appears along the spirals then disappears into the center hole and lands in a cup?

For those of us who process lots of black sand the choices on how to process the sand is limited to panning, using a "Micro Sluice" or a spiral gold wheel.

After panning for many years I always ended up with back sand in the gold...ALWAYS! The micro sluices work OK but are slow and I still end up with black sand with the gold. However when properly set-up and run, a spiral gold wheel will process 50 pounds of concentrate an hour and give you perfectly clean gold!

So if you run lots of concentrate, do not want to sit for hours on end (no pun intended) the spiral gold wheels are worth consideration.

Operation
Many years ago Gary Christopher, owner of Prospectors Cache Prospecting Store and a spiral gold wheel manufacturer, was asked if his gold wheel was any good. His answer then is as valid today was, "The wheel is only as good as the operator!" If you do not understand the operational theory of gravity separation, and understand the importance of classification of the gravel to be run into a 3 to 1 ratio then the results will probably be poor.

recovered gold Black sand concentrates are a combination of minerals in the iron group: Hematite, Fe3o3, with a specific gravity of 5.26, an iron mineral that is non-magnetic and Magnetite, Fe3o4, with a specific gravity of 5.20, is magnetic. These black sands will weigh a third (1/3) to a fourth (1/4) the weight of gold (Au). Gold has a specific gravity of 15 to 19.3. A cubic foot of wet black sand will weigh 225+ pounds or 26.7 pounds per gallon. These heavy concentrates present the major problem in the gold recovery process for the average recreational gold prospector. Gold with a specific gravity of 15 to 19.3 and black sand at 5 to 6, when classified to the same mesh size, will allow the gold contained to be easily recovered. Without classification, gravel three times the size of gold will be recovered with the gold, hence the necessity for proper classification. With the 3 to 1 ratio in mind start by classifying your concentrate to 10 mesh. Run material through the gold wheel and gold contained in cons will be recovered in the 10 to 40 mesh size. Screen concentrate again with a 40 mesh screen and rerun. Your gold wheel should recover any remaining gold in the 40 to 120 mesh class. Beyond this point you must have experience in water pressure and the use of a surfactant to recover any existing microscopic gold.

For best recovery your gold recovery machine should have a green or blue wheel. You should use Jet Dry®, at the rate of three drops per five gallons of water to prevent gold from floating out of the wheel. The tilt of the wheel should be 45 degrees to start, water flow adjusted to an even flow without splash and the black sand pyramid adjusted to an inch below center hole. Use wheel tilt to adjust pyramid, not water flow. Once the water flow is properly set, no further adjustment is required. Check gold cup for black sand and re-adjust wheel if necessary. It is possible to recover over 90% of the gold in your concentrate if your wheel is properly set-up and your concentrate is properly screened.

The new age of computer designed gold wheels with built in agitators are well worth consideration. The new agitator wheel, turquoise in color, will fit most all older 13" gold wheels and pay for itself in short order. Also available is a micro adjuster for the older 13" gold wheels that allow micrometer like adjustment for near perfect gold recovery.

For further information on where listed products can be found, E-Mail questions to Prospector Pete at:
goldprosp@earthlink.net

The Blue Bowl

Of all the black sand separation methods, the Blue Bowl will probably save the finest gold without resorting to mercury or other chemicals. It used to be called the D.A.M. Bowl but Pioneer Mining in Auburn, CA aquired the patents and the molds and now it's just called the Blue Bowl (I can't imagine why). They work best with materal that will go through a 30 mesh screen but I have had pretty good luck with material between 20 and 30 mesh. Any of the black sand separators mentioned on this site or a gold pan will work OK for material over 30 mesh. You can buy just the bowl or in a couple kits one of which has virtually everything you need.

If you bought one years ago, the instructions weren't all that great. Much improved instructions are available on Pioneer Mining's web site.

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