Simple methods for the treatment of gold
by Gary Livermore,
[email protected]
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Separating the find gold from your concentrates
The simplest and cheapest way for the small-scale placer miner to retrieve the fine gold from the concentrates can be done in six simple steps. You will need a plastic gold pan, distilled water, household lye, an ounce of mercury, nitric acid, a Pyrex measuring cup, safety goggles, rubber gloves, and a rubber apron, a flat copper bar or sheet of copper, and assorted sizes of gold vials. You also may wish to use a miner's magnet. If you have a rock tumbler, you will need a piece of hexagonal steel bar that will fit into the tumbler or several stainless-steel ball bearings.
Place some concentrates into a plastic gold pan (about 1/2 full) and cover the concentrates with distilled water. Add one tablespoon of household lye to the concentrates and swirl the liquid around for several minutes. This will remove surface impurities, such as dirt and oils, from the gold. If you have a rock tumbler, use that instead. Fill the tumbler 1/3 to 1/2 full, cover with water, add 1 tablespoon of lye to it, and let it run for about one hour.
Pour off the lay-laden water and add fresh water to it, and add one ounce of mercury.
WARNING! When using lye, you should wear safety goggles and rubber gloves (and a rubber apron would be a good idea, too) to avoid getting any spilled or splashed on your skin or in your eyes.
WARNING! When using mercury, you should wear safety goggles and rubber gloves (and a rubber apron would be a good idea, too) to avoid getting any spilled or splashed on your skin or in your eyes.
WARNING! Do not inhale any fumes from from lye or mercury!
Slowly swirl the contents with the mercury. As the mercury goes around the pan, it will pick up all the finest gold in the pan. The more gold there is, the stiffer the mercury becomes. If using a tumbler, do the same, but in a tumbler you can add a hexagonal stainless steel bar to roll with it inside, or several stainless ball-bearings. The steel bar will help grind the black sands, and release any gold that is attached to the black sand. Run the tumbler for at least three hours.
Once you have all the gold gathered, pan off the black sands, or use a magnet in a plastic baggie to retrieve the black sands, leaving only the gold-laden mercury and free mercury. The free mercury will roll around easily, where the gold-laden mercury is stiff and does not roll well. Place your mercury container INSIDE another gold pan, and pour off the free mercury into the container. Using another pan keeps it from spilling out onto the floor or ground. If you spill mercury on the floor (or the living room carpeting), you will be inhaling evaporating fumes for years!
Now that you have a solid ball of gold-laden mercury in the plastic pan; flush it out into a glass measuring cup. (I buy Pyrex pie pans and cups at thrift stores all the time.) Now add enough water to cover the mercury ball. Working outside and up wind, add a few drops of nitric acid (usually available in small bottles at prospecting stores). Keep adding nitric acid until you get a bubbling or fizzing action from the mercury (avoid breathing the fumes!). The acid will dissolve the mercury as well as any trace silver. After a while, the fizzing stops and at the bottom of your cup is a bronze-colored metallic looking blob; it's GOLD! You can reclaim your dissolved mercury from the nitric acid by placing a flat copper bar or copper sheet into the acid and letting it sit overnight. The next day, the mercury will have come out of solution and attached itself to the copper and then you can scrape the mercury from the copper and put it back into your storage container.
Carefully pour off the remaining liquid and neutralize the acid with baking soda, a little at a time until you get no reaction from the acid and baking soda. Gently rinse the gold in the cup with fresh water, avoiding hard sprays that could wash the gold right out of the cup. Let it sit somewhere until it is all dried out. Now you can use whatever method you prefer to transfer your gold from the cup into your gold vials.
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Melting and making a Doré button
When you think you have enough of that fine flour gold saved up and you want to pour a "button," the following procedure works well. You will need a briquette of charcoal, some borax, and a propane torch.
Carve out a small depression in a piece of charcoal just big enough to hold your gold. You can use a charcoal briquette if you first flatten the top and bottom of the briquette so it won't rock or wobble.
Put your fine gold in the depression.
Light your propane torch and play the flame over the gold. Gold has a fairly high melting point, so it may take a while. Continue with the flame until you have a bright red "bead."
WARNING! Some propane torches have a habit of flaring up a bit when you tip the flame end downwards. Be sure you have a low flame and that the propane bottle is at a lowered angle before placing the flame on the gold. A sudden flare-up at this point could blow your gold right out of the hole, so have it adjusted first.
Keeping the flame on the gold, add a pinch of borax to the gold, and turn up the heat slightly and carefully. As the gold gets hotter, it changes color to a bright greenish-orange as it nears it's melting point. All the fine particles of gold will melt together into a bright ball.
Remove the flame and let it cool down slowly on it's own. After it has cooled, you have your first Doré button and it will be nice and bright and shiny. Fine gold is more pure than larger gold and, because we used nitric acid earlier, we reduced some of the silver that was alloyed with the fine gold, making it even purer. This Doré button could run 95- to 98-percent pure, with traces of silver and copper.
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Creating Nugget Jewelry
Creating nuggets to make jewelry is just one way to double and triple the value of your fine gold. You will need a Pyrerx glass measuring cup, stainless-steel tweezers, and some sulfuric or Muriatic (Hydrochloric) acid (you can purchase sulfuric acid at some prospecting stores or at pool-supply stores).
Fill your glass cup half full with sulfuric acid (see cautions above about using acids). After you melt your gold in the charcoal block as in step 4 above, quickly pick up the charcoal block and pour the melted gold button into the cup of acid. As it quickly cools, it will form interesting shapes. Each time you do this, it forms a different shape. You can make small ones for earrings, or larger ones for pendants, etc.
Remove the faux "nugget" with stainless steel tweezers and rinse it with tap water. If the texture is too "rough" looking, you can tumble your "nugget" in a tumbler with water and fine sand to smoothen out the edges and give it that more natural look.
Pour the acid back into it's container and rinse out your glass cup with water.
Note: Remember, a little home-made nugget is SOLID gold, not plated! To sell your gold as Doré buttons, it would need to be assayed first. To sell to a dealer, you could lose 12 percent or more of spot price. Making jewelry though, you can't do anything but triple the value of the gold! If you had a 1/4 ounce of gold, at 95 percent pure, it would be worth $95 at a spot price of, let's say, $400 per ounce. Now, subtract 12 percent buyer's fee and you end up with just $83.60. Taking that same 1/4 ounce of fine gold, creating a "nugget" out of it, and then making jewelry out of that, you could get $200 to $300 for it! Quite a difference!
One other note on black sands: Sometimes black sands carry values of gold that cannot be seen because of impurities or chemical bonding with a few other minerals, such as selenium and tellurium, which would have to be chemically broken down to reveal the gold. Silver is not silver-looking in nature, but rather a dark gray to black. Platinum has actually been dumped out because it wasn't seen. The best thing is to either take a well represented sample down for a fire assay, or do a chemical assay yourself. At the least, get a pestle and mortar (cast iron), crush a sample down to dust, and pan it out to see if there is any color there. But never toss away black sands unless you are sure it is void of ANYTHING of value. Actually, if you had a dozen 55 gallon drums of it, you could make a tidy sum of money!
