carbon/gold assay

[Anonymous]

Hi

Does anyone know the process for determining gold in carbon assays... as in the carbon used in the cip process for extracting gold. (coconut, peach etc)

Ive tried the AR process and then stannous spot test on carbon against known lab assays and havent been able to get any colour at all in the test however the gold from the lab assay showed 5500ppm.

Im trying to find out what i can use for field spot tests that can show me a ballpark figure and if the sample was to kick then follow it up with a more accurate lab test. Where i live the labs are charging around $150 for a carbon sample so before i actually pay for the sample i would like to know the carbon is at least holding some values before submitting to the lab.

I have a smelting furnace and access to most chemicals and am a bit lost as to the gold in carbon testing procedure

Any help would be greatly appreciated

Thanks Kym

 

[goldsilverpro]

I don't think AR will leach gold from carbon. The gold is in there as a cyanide complex. When you add acid, you form a precipitate of the gold, AuCN, which is insoluble in acids. It is yellow in color and, if you can see any yellow powder on the carbon after treating with an acid, it could be an indication of gold. Use an eye loupe.

You might try incinerating the carbon sample before using AR, but this won't work unless the gold cyanide complex breaks down..

You could leach out the gold with stronger cyanide and then analyze the solution.

Although you would be limited in sample size to several grams, you could "wet ash" the sample in hot concentrated sulfuric acid, UNDER A HOOD. The carbon will dissolve, the cyanide holding the gold would decompose, and the gold would be left as a brown sponge which, even in small quantities, is very visible in the bottom of the flask. Hot concentrated sulfuric is always dangerous and this method is not for the fainthearted. If you need details on this, let me know. I have written it up several times on the forum.

 

[makmur mulia]

I have question related to activated carbon (AC) inceneration. By burning activated carbon loaded with AuCN, I assume we will get uncombustible matters (metal materials and ash). Can we process these uncombustible matters using HNO3 to get silver, and accordingly AR and SMB to get Au?
Many thanks.

 

[Richard36]

I suppose so.
Hank Chapmans book, "How to Smelt Your Gold and Silver", says to ash the carbon, mix 1 part ash with 3 parts flux and smelt in order to recover the Precious Metals in Dore form, which could then be further refined with the methods found on this forum.

Just a thought, and I hope that it helps.

Sincerely; Rick. "The Rock Man".