Silver Encapsulated gold

[GTC]

I ran a small batch ( 20 grams ) of 14 kt gold that contained diamonds. I did not want to damage the diamonds to I did not granulate the gold. The aqua regia dissolved the majority of the alloy, and I was able to recover all the diamonds. However, I have a few large silver clumps that I was told was silver chloride encapsulating the gold. How do I go about reclaiming the gold from these?

Thanks,

GTC

 

[4metals]

Place the silver encrusted alloy in ammonium hydroxide to dissolve the silver chloride crust. Remove the gold pieces and weigh them. Add 3 times the weight in silver to inquart and part in 50% nitric acid. The gold will not dissolve and will remain on the bottom. Refine the gold in aqua regia the normal way. Cement the silver out of the nitric acid to re-use again as cement silver, and add HCl to the ammonia waste to drop the silver as silver chloride. Accumulate the silver chloride until you have enough to reduce with caustic and sugar. While accumulating keep the chlorides wet and preferably in an opaque bottle.

 

[Woolf]

will the gold remain in solid form? or will it turn into a powder form after placing it inside of nitric? also do you need to add 3x silver? or can you just go directly into nitric after boiling it inside of ammonia

 

[4metals]

If the alloy was high in silver it will still be high in silver after ammonia, the only difference is the encrusting silver chloride will be gone. (dissolved in the ammonia) You can go back into aqua regia but if there is any thickness there it will happen again so you will have to re do the ammonia treatment, then the aqua regiua again until it's gone. If the stones are out, or loose enough to pry out easily, inquart with silver and dissolve in nitric it is easier in the long run.

The gold will be a solid granular deposit on the bottom after nitric acid treatment, looks like coffee grinds. It's usually about 99% pure.

 

[OneZip87]

Just from experience sometimes agitating the "caked" pieces helps remove the silver chloride also heating can expidite the process a little.

Another alternative it to just dissolve ALL of the gold using AR (just rinse the "caked" pieces with ammonium hydroxide and add fresh AR)and they should dissolve, then just recover the gold from solution.

I find this works easiest for me, but it may not in your situation

 

[Woolf]

Just from experience sometimes agitating the "caked" pieces helps remove the silver chloride also heating can expidite the process a little.

Another alternative it to just dissolve ALL of the gold using AR (just rinse the "caked" pieces with ammonium hydroxide and add fresh AR)and they should dissolve, then just recover the gold from solution.

I find this works easiest for me, but it may not in your situation

so you skip the nitric step and just go from ammonia to AR again?

 

[Harold_V]

so you skip the nitric step and just go from ammonia to AR again?

I'd be a little careful with that idea. If memory serves, ammonia and gold chloride form an explosive compound.

Harold

 

[Woolf]

so you skip the nitric step and just go from ammonia to AR again?

I'd be a little careful with that idea. If memory serves, ammonia and gold chloride form an explosive compound.

i was asking if thast what he did..

 

[goldsilverpro]

I don't think fulminates or azides can form in an acidic solution.

 

[Harold_V]

I don't think fulminates or azides can form in an acidic solution.

The problem, as I see it, is the guy that tries to reinvent the wheel and does some stupid things.
The solution for silvering mirrors is perfectly stable so long as it doesn't dry out, or so I'm told. That's just a simple example of how a guy can get in trouble inadvertently.

I don't know the details, but a guy with a degree in chemistry had an explosion at the UofU many years ago. He was working with a gold compound of sorts. It happens. As a result, it pays to be careful and stick to known procedures.

Harold

 

[OneZip87]

I rinse it with water and add some HCl to neutralize the rest of the ammonia, other wise what would be the point of using a strong acid if you just add it to a base

Also I did the reaction steps before I started and I didn't see any explosive by products (a hobby of mine in college was the chemistry of nitrogen based explosives)

 

[OneZip87]

Also my appologies for not enumerating all of the steps. In my haste to be helpful I missed some important additions

Thanks for the check, I hope my omission didn't cause any harm

Nick