Separating Gold And Silver

They have kits that you can probably find online that places like Pawn Shops use. It will help you find out if a piece is silver or not and the karat of the gold. It's only an estimate on the gold, because sometimes it might be a 16kt piece and the acids usually come in 10, 14, 18, and 22. As far as the silver goes, it will only give you a "yes/no" answer. To find out the purity, that will definitely need to be melted down, if not marked.

Separating metals from each other is usually not difficult chemistry but it does require certain equipment that is likely not very cost effective for anyone doing this on small amounts of feed materials.

Yes, nitric acid will dissolve silver but not gold. The trick that makes this effective though is to have a very small particle size, so that you don't have a lot of silver occluded by large gold particles. A particle of silver wrapped in gold will not dissolve in nitric acid and will contaminate the final product. Because of this, the sample must be ground to as fine a powder as possible prior to acid leaching to remove the silver. Something like flour in particle size should be good enough.

Once the silver is in solution as silver nitrate, it should be possible to precipitate it back out via neutralizing the acid and adding ammonium chloride to produce highly insoluble silver chloride. This can be filtered off, washed with distilled water, and then roasted at high temperature in the presence of of H2 gas to drive off the resulting HCl. Any resulting HCl gas would then be trapped in a caustic scrubber to prevent it from harming anyone doing this work.

Note that H2 gas is highly flammable and forms explosive mixtures with air over a wide range of H2 percentages. Extreme caution is advised as is performing such work in a chemical hood device that is in good working condition.

Carbon might also work as a reducing agent but I'm not sure how well it would work. It works very well with oxides but might or might not be effective with chlorides. If it did work, then low molecular chloro-methanes would likely result. A hood would be needed to ventilate the work area.

As you can see from this explanation, a lab equipped for wet chemistry would be needed to do this work effectively and safely. A good knowledge of the safe handling and disposal of the reagents needed is also required.

Also, one other detail...I will be doing this in a remote jungle area, outdoors, not many fume problems.

, trac!

Thanks for asking, might be handy to know.

trac,
You maybe better off taking your ore down to a concentrate level and then have a refiner work it down for you. You say you will be out in the jungle so maybe packing back the concentrates is not an option. But I have the feeling that you will find the process to be prohibitive for your levels of production.