Is gold in my silver chloride after AR?

[bhilton]

Hello everyone!

My jeweler friend gave me some mixed gold strips to process and to practice with.

He took the filings and dust from his work bench catch tray and melted them into buttons and rolled them out to thin strips.

The metals contained in these strips could be anything a jeweler works on, he could not say.

He used his electronic gold karat testing machine and the strips tested at 10k to 12k - although the accuracy of his machine is likely imperfect.

I put the 31grams of strips into AR and stirred occasionally while the metals dissolved over the course of 1 hour.

I stirred the solution frequently for another 5 minutes at the end. I added 35ml of nitric to start and added 10 more ml near the end (in small increments). I could not see any more reactions happening so I increased heat to a small boil and denoxed with sulfamic acid.

I have already precipitated the gold from the filtered solution with smb, done a final stannous test, settled it for 24 hours, and washed it. I'm going to guess the gold dust is 7-8 grams.

After filtering I was left with a lot of silver chloride mud. How can I tell if there is any gold in the silver chloride mud? I'll post a picture shortly.

 

[bhilton]

 

[justinhcase]

Back a long time ago when I was trained to collect samples for latter analysis, I was taught the Locard's exchange principle.
The Exchange Principle can be summarized as whenever two objects come into contact, a transfer of material will occur.
This is more so when those materials are very well mixed to start with and not just experiencing a glancing contact.
In truth, you will just about always have some carry over, if you are very proficient at digestions you might make the trace impurity so low that they are hard to detect.
But that will be it, how sensitive a system of testing are you using.
This is the main reason a good waste system is so important.
If you can easily detect a content, you will need to look at every thing from your inquartation, to base metal leaching.
Sometimes you may need to use a large ceramic mortar and pestle to grind up your digested alloys to expose any undigested alloy which has been pacified.
Then again during A.R. to ensure you have you a full digestion.
You would be surprised how value can hide from acid sometimes.

 

[Yggdrasil]

View attachment 61892View attachment 61893

There is no Silver Chloride here, just grey sand.

 

[Yggdrasil]

There is no Silver Chloride here, just grey sand.

Did you mix up the picture?

 

[bhilton]

Did you mix up the picture?

No, that’s the picture. But Oh!! The sand is highly likely aluminum oxide from his sand paper.

Here is another pic after I swirled it around. Silver chloride and aluminum oxide sand looking bits?

I want to make sure I get all the gold from it, if any still exists.

 

[Yggdrasil]

No, that’s the picture. But Oh!! The sand is highly likely aluminum oxide from his sand paper.

Here is another pic after I swirled it around. Silver chloride and aluminum oxide sand looking bits?

I want to make sure I get all the gold from it, if any still exists.


View attachment 61894

Hmm.
There will probably be some Gold solution locked up inside the mud/sand.
You need to rinse it until there is no more positive Stannous test then maybe try to leach it again with some stirring.
If there is Gold left then it will dissolve.
Then you can do a Lye/Sugar conversion with the Silver Chloride and leach it out of the mud/sand with Nitric.
But if it is worth it I can't say.

But the

 

[bhilton]

Hmm.
There will probably be some Gold solution locked up inside the mud/sand.
You need to rinse it until there is no more positive Stannous test then maybe try to leach it again with some stirring.
If there is Gold left then it will dissolve.
Then you can do a Lye/Sugar conversion with the Silver Chloride and leach it out of the mud/sand with Nitric.
But if it is worth it I can't say.

But the

ok, I will try what you suggest when I have some free time.

Thank you!

 

[Yggdrasil]

ok, I will try what you suggest when I have some free time.

Thank you!

The important question is if it is worth the time, effort and expenses.
Only you can decide.

 

[bhilton]

The important question is if it is worth the time, effort and expenses.
Only you can decide.

I completely agree with your thought process.

I want to see what I can get out of it, to learn and to gauge how viable it could be if I collected a larger lot of it (over time).

My friend has another 45 grams of the same material for me to process. Would you do anything different?

Would you give it a hot nitric bath, pour off dissolved base metals, and rinse with hot water before going to AR?

The material is estimated to be 10-11karat gold, the rest will be a mess of whatever metals were in many different pieces of jewelry that he has worked on. This also includes a bunch of sandpaper bits, aluminum oxide, mixed in as dust and melted into buttons by him.

 

[Ayham Hafez]

From second photo, it looks like the gold button was not melted well, my suggestion is to melt it first to get homogeneous gold button, add some silver to make sure gold content about 30%, add borax and soda ash while smelting to get rid of sands and other oxides as a slag, after finish melting, take the gold button and clean it from slags by crushing the slag using small hammer, after you got a clean gold button roll it to get a large surface area or melt again and pour in shots, then go with nitric acid to dissolve base metals then AR

 

[4metals]

A lot of smaller refiners spend their energy chasing to be sure they get all of the gold. I have always been willing to accept 1% gold assay in the reduced melted chloride residues because it all came out in the Silver cell. But I am talking operations with labs to do the analysis and Silver cells.

One sure way to get all of the gold in one spot is by inquarting with Silver and parting in nitric acid before aqua regia. This will assure all of your gold is where you want it and your residual Silver nitrate from the parting of the Silver has no gold.

We recently had a thread from a new member in Vietnam who compared the 2 methods, inquarting and direct aqua regia. This works on both small scale and large scale. And on the smaller scale you can always come up with an old sterling fork or spoon to use for Silver until you collect enough. Check that thread out HERE.