New to smelting, questions abound

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woodsmit

New member
Joined
Aug 21, 2022
Messages
2
Location
Janesville
Totally new to smelting.
First: I have a friend who lost her cabin in the woods to the Dixie Fire last year. She asked if I could do anything with her melted gold jewelry that went through the fire, what is the best flux to get rid of the smoke and junk in the melted balls of mixed jewelry?
Second: I have an 86 year old prospector friend who finally found a claim that he staked forty years ago. I am hoping that we can prove it up before he passes. So - we are in sulfides with copper ores next to sulfides with micron gold. We can crush a lot of it to 100-, and pan or spiral wheel to concentrates. But what is the best flux for smelting concentrates?
There is a lot for me to learn and undoubtedly there will be a steep learning curve. We have a new, small, electric crucible for test runs.
Happy to be here, and a shout out to all the old timers.
 
For the gold jewelry, I would recommend not trying to smelt with flux to clean up the metal, but rather to run it through a full refining process. That glob of gold is going to be a mix of gold, silver, copper, etc. By chemically refining it, you would be able to separate the precious metals from their fillers.

Elemental
 
There are many processes for jewellry, depending on purity, metal and others.
If it is Gold higher than 6 karat but below 18-20 ish you need to inquart, and then part it.
If its Silver it is mainly Nitric.
And then there is Platinum, White Gold, Green Gold and so on.
 
The refining process as a whole can be found in the book in my signature block by C. M. Hoke. Simply put it's the separation and purification of precious metals by chemical means. I would recommend taking a look at STREETIPs on youtube, as his video series shows multiple methods for refining.

As a personal example, I take old sterling flatware, jewelry, and other pieces and remove the copper that makes it sterling silver to make pure 99.99% silver bars. I use chemical methods (nitric acid) to remove the copper then electrochemical methods to further refine (a silver cell).

Elemental
 
The refining process as a whole can be found in the book in my signature block by C. M. Hoke. Simply put it's the separation and purification of precious metals by chemical means. I would recommend taking a look at STREETIPs on youtube, as his video series shows multiple methods for refining.

As a personal example, I take old sterling flatware, jewelry, and other pieces and remove the copper that makes it sterling silver to make pure 99.99% silver bars. I use chemical methods (nitric acid) to remove the copper then electrochemical methods to further refine (a silver cell).

Elemental
by removing the copper you mean dissolving the item in nitric and then dropping out the silver leaving the copper in solution?????
 
by removing the copper you mean dissolving the item in nitric and then dropping out the silver leaving the copper in solution?????
Yes, that is a simplified method of explaining it. Some other things of note are to incinerate (hit it with a torch for a bit) the stock metal first to remove waxes, oils, etc from the metal. As a chemist, I enjoy the math aspect of it along with the "wet chemistry". Calculations of limiting reagents, etc. Here are the simplified instructions off the top of my head:

01 - Get Scrap Sterling (The hardest part is trying to get it for less than spot price, I shoot for 80% of spot as my maximum for it)
02 - Confirm it is Sterling (You want a bad day, have a piece of pewter, German Silver, etc sneak past you.
03 - Incinerate the Sterling (If you pay attention here, it will help with identifying Sterling vs. Junk)

NEXT STEP SAFETY NOTE: PROPER VENTALATION OR DEATH (If you can smell the acid fumes, you're doing damage to your lungs)
Reminders: No metal, no matter what the price, is worth dying or injuring yourself for. Use PPE and Safety Equipment i.e. Fume Hood.

04 - Dissolve in Nitric Acid/ DISTILLED!!! Water (You need a certain amount of water to carry the Silver/Copper Nitrate)
05 - Keep adding acid in small (or calculated) amounts while under heat (do not boil) until silver is gone
06 - Put in another piece of sterling and let it sit for a bit to use up excess acid (Nitric is expensive, don't waste it), add a few drops of sulfuric acid to drop any lead from solution.
07 - Filter the solution: There may be Gold or PGM's here that didn't dissolve, along with other junk
08 - Dilute the solution by 100% (Failure to dilute will yield a fast forming silver crystal grown on your copper, which contaminates it and stalls the reaction)
09 - Add copper metal to the solution (I use heavy gauge copper wire that I can form into shapes)
10 - Allow all the silver to fall out of solution (This is really beautiful to watch, my daughter loves this part)
11 - Put remaining solution in a stock pot (put copper fittings in here, excess silver will fall out over time)
12 - Rinse with hot water silver cement several times until no blue rinse water remains (put rinse water in stock pot)
13 - Dry silver cement in a small crock pot overnight
14 - Put dried silver cement in crucible and melt in low oxygen environment (Molten silver absorbs x20 it's mass in oxygen from the atmosphere)
15 - Pour ~99% pure silver into plate mold
16 - Use silver plate as anode for silver cell
17 - Plate out silver crystal on Stainless steel at ~3.5volts over several days
18 - Scrape Silver Crystal off stainless plates, rinse with hot water (rinse goes in stock pot)
19 - Melt silver crystal and pour into ingot
20 - Weigh, Stamp, and Store until my daughter goes to College and I sell all this metal
21 - Treat the stock pot, and then process the waste copper nitrate (This is a whole other set of instructions) (Do not let your waste pile up!)
22 - Repeat...

Hope this helps. I have much more detailed lab notes in my lab that I follow.

Elemental
 
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