removing super fine gold from black sands

[DanB]

should I use a kiln if so what temp should do the trick, looking at kilns, they have different firing temps from 900 deg to 3000 deg, how much flux do I use in ratio to black sand? would a tumbler and mercury do the trick? if so how long do I need to tumble? then use a tort to remove the mercury from the gold? I have a few hundred pounds of black sands, I have them sorted and separated by magnetite and hematite. any help would be great,

I am in phx, and most of the black sands come from the Bradshaw mountains.

 

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[AuExplorer]

No worries.

You have a multitude of avenues open to you. Kiln's are great if you have extra cash, but some of us "grassroots" types just slap together a small forge. Regardless of forge or kiln, about 1600 to 1800 degrees will suffice. Flux's are a matter of preference.
1) remove as much dirt as possible.
2) Do not tumble with mercury unless you have extensively ground the material to remove any sulphide coatings.
3) a trick that works wonders instead of tumbling is copper plate amalgamation. Put on heavy duty chemical gloves and( mix 2 parts distilled water to one part nitric acid.Add drop of mercury and warm the solution if needed. Once the mercury has been taken into solution,You now have Mercuric Nitrate.
4) Take a copper gold pan and scuff with sand or steel wool to remove any dirty and provide a clean surface.
5) Take a pair of forceps and a cotton ball and slightly dip into solution. Rub the pregnant cottonball over entire working surface of the copper goldpan or plate.
6) put cottonball in airtight container and save for next application.
7) while your pan is setting up, fill a panning tub ( that will never be used for anything other again with non chlorinated water.
8) Add a small amount of your gold bearing material to the pan, dip the pan in the tub and gently move the material around until you are satisfied with your recovery. dump and add more material and keep going.
9) once you are satisfied with and feel your mercury is loaded, take an old credit card or small squeegee and scrap the pan into a catch pan.
10) redo step 5 and keep panning.
11) once you have collected all of your scrappings from your run, Mix one part distilled water and one part nitric and add your scrappings to it. Keep track of amounts, because we are going to turn that solution back into mercuric nitrate when we are done.
12) warm solution if needed.
********That black powder in the bottom of of your mixing container is your gold.*************
13) filter through 2 coffee filters and dry.
14) fire with flux of your choice for 99 fine
15) take solution from coffee filters and add one more part distilled water and you are ready to go again.
16) Care and attention is required for this. It is safe other than the nitric. Mercury is fun, mercury fumes and vapours KILL. No retorting required and you if you are careful will only lose minute amounts of mercury and far less than retorting.
17) I preffer rubbermaids to to do the entire operation in, to keep area contamination to a minimum.
18) if you need better directions, or need other direction, just PM me.
19) ***** A propper flux cap is essential for a good heat. More people have messed up their gold by
a flux cap that has been poorly laid ( borax likes to expand and lift exposing your material to pure heat)
thourgh mixing is a must. Another mistake is trying to fire to little material.

I know it is hard to hold on until you have an amount worth firing, but those of us that have been there and learned by error will agree, wait...wait...wait... then fire

P.S. please do not use this method in the field, As temping as it would be to place a "tinned or silvered" 48"x48" copper plate directly into the stream and use a 12" squeegee. it is illegal and harmful to us all.
I have provided a friendly and safe way to use mercury, Have fun and remember years from now, where ya heard it.

 

[ChuckNC]

Dan,

You have a number of methods to recover fine and extra fine gold other than Hg. I have access to a fair quantity of Hg but prefer not to use it. It's all a personal choice. Remember, Hg will not get all the fine gold. Then there is the problem of contamination and proper disposal. These can be costly in the long and short run.

No matter what you plan on doing I'd first crush the blacksands as fine as possible, then roast the cruchings to remove all organics. From there you can use several mechanical devices to recover the gold or leaching.

You mentioned firing the black sands. This is a sticky idea(pun intended). I currently have 2 crucibles that have the gold trapped in a glassy mess. I'll have to get a professional flux to correct the mess. I used a flux I got the formula from off the net, and was unimpressed. Fluxes are a tricky subject. The formulation depends on what materials are pressent in the blacksands, and in what amounts. It's not a simple add borax and run situation.

Here's an impressive video of a company in Alaska that has a good setup.


Of course, a good super cons would be worth firing. Less trash to have to use fluxes on.

There are several other alternatives to the table these guys use. I prefer the old Kenne Green Bowl myself. I find it to be better at retaining fines better than a gold wheel. But that's just me.

Email me if I could be of any help.

Chuck