Method for producing pure silver metal

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Nice post, Lou.

Food for thought: Silver nitrate can be allowed to grow crystals, which will reject the majority of impurities contained in solution. Collect the crystals, re-dissolved in distilled water, than allow them to grow again. Each iteration raises the quality of the silver.

Harold
 
Lou,

If I understand you correctly then if I had a silver cell that the electrolyte has become overburdened with Cu the addition of sodium carbonate will give silver carbonate with limited drag down of Cu.

In addition I would think that you could recover your nitric from the filtrate buy simple heating and a condenser coil and get a rather pure nitric. The sodium will not carry over but is there a problem with the carbonate that I am unaware of that would affect the purity of the resulting nitric?

There would be a fair bit of nitric bound to the Cu so I wonder if I would have to stop short of heating the filtrate dry to recover the nitrate from the Cu without impurities coming over from the carbonate or sodium. In the case of heating to dryness I would have the condenser output bubble the gas through distilled water. If I am not pipe dreaming here what temperature is needed to break the bond between the Cu and nitrate?
 
If you have excess nitric acid that means excess protons and that means you'll be making CO2 gas and sodium nitrate. Residual carbonate will remove any copper and most other base metals out of the system. You'll be left with sodium nitrate solution and probably quite a bit of effervescence.


As for separating silver carbonate from copper carbonate, it would not work well unless there was strict pH control--copper carbonate isn't very soluble, less soluble than silver carbonate even. I meant this as an easy way to get pure silver from pure silver nitrate in a jiffy. It's no a repurification step. If you fuses your silver nitrate and hold at 425 C all of the lesser metal nitrates will decompose into oxides with the release of nitrogen dioxide. Cool and break up the luna salt cake and dissolve in water, filtering out the base metal oxide residues. This is then reacted with sodium carbonate, filtered, and the precipitate heated to yield pure silver. It can also be melted straight from carbonate.
 
Hey guys - I was reading this thread with interest and wondering, when using Ammonia, what % of ammonia should be used and what ratio/silver?
I realize this is an old thread, but maybe someone can answer

Regards

Arie
 
If the silver is pure you wouldn't experience any loss if using it to rinse. The ammonia will form complex with silver ions, that is if any chloride oxide or nitrate is available. I do this all the time and at strengths between 5 and 10% NH4OH
 
When using the AgCl/sugar method i usually lose around 10% of the silver through washing. I think most silver is lost when I remove remaining sugar and NaOH because the silver particles are very small in that state of the process.

Is it better to use only NaOH and no sugar and put the AgO into the furnace?
 
Goldfinger4 said:
When using the AgCl/sugar method i usually lose around 10% of the silver through washing. I think most silver is lost when I remove remaining sugar and NaOH because the silver particles are very small in that state of the process.

Is it better to use only NaOH and no sugar and put the AgO into the furnace?
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If you suspect you are losing silver in the washes you have to filter the washes better. You should decant the lye/sugar solution saving it in another vessel and then filter the solution. A "charmin plug" or other very fine filters should work. If you think you're losing alot of silver the way you're doing it now you would be extremely dissappointed trying to melt silver oxide straight away :shock: So no its not a good idea.
 
Noxx said:
Following steps must be performed in a low light environment.
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goldsilverpro said:
Light is a problem. Maybe you could use a red photo lab light.
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I know how AgCl changes from white to purple in light, but I didn't know that it harms anything for it to turn. How does light effect the silver while refining?
 
Noxx said:
-Add NaCl (lab grade, food grade or equivalent) until no more precipitate forms. You now made Silver Chloride (AgCl) and Lead Chloride if there was any present.
...
-Now dissolve your powder in Ammonium Hydroxide (lab grade, try not to use too much). Ammonia water will form a complex with silver but will not dissolve any lead chloride that may have still been present.
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I know you started with sterling, but I work with more e-scrap than sterling, and this would make this more a concise process. I would suggest that:

...You now made Silver Chloride (AgCl), Lead Chloride (PbCl2), Mercury Chloride (HgCl2), and Stannous Chloride (SnCl2) if there was any present.
...Ammonia water will selectively form a complex with silver but will not dissolve any PbCl2, HgCl2, or SnCl2 that may have still been present.

This is knit-picking, but I fought these others when I first started refining. It would have made life easier if I had known more about them.

Richard
 
Never leave your silver solutions basic, always add some HCl to them, enough to bring the pH to slightly lower than 7.

This will push any silver out of the solution that may have become tied up.

Steve
 
goldenchild said:
If you suspect you are losing silver in the washes you have to filter the washes better. You should decant the lye/sugar solution saving it in another vessel and then filter the solution. A "charmin plug" or other very fine filters should work. If you think you're losing alot of silver the way you're doing it now you would be extremely dissappointed trying to melt silver oxide straight away :shock: So no its not a good idea.
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Why would I be disappointed? Silver in the oxide should not disappear while melting. I could imagine that it would be dangerous having dissolved much oxygen in the liquid silver as I normally only wear gloves, a leather jacket and protective goggles when casting..
 
Looking for answers. I received some old pieces of what is supposed to be sterling silver (no hallmarks but stamped sterling silver 1880.) I melted one damaged piece into small ingots (about 1oz. each) so that I could experiment with silver refining. I tested the ingots with red acid and it turned a yellow green color indicating that the silver content was below 75%.
I then dissolved the silver in 70% nitric acid dilluted with distilled water.
Shor says no water is necessary? After the silver was dissolved, I filtered it and precipitated it with table salt (no iodine). I filtered again and washed and dried the white compound that had dropped. I then transferred the white compund to a clean plastic bowl, added distilled water and introduced lye beads. The white compound turned reddish brown? I then added corn syrup, stirred and poured off the liquid. I was left with a reddish brown mud ball? I dried the mud and then melted it. It did turn a bright shiny silver but it seemed to melt very fast? I then retested with red acid and it still is a yellow green color. Any ideas? By the way, you guys are awesome in taking the time to explain this stuff to neophytes like me. I do appreciate it.
 
Going to a chloride would still not produce a fine silver product and since your testing showed lower silver you may have lead in there. This comes down with the silver chloride and ends up in the next bar if you don't rinse it out with hot water rinses.

Next time dissolve it in 50% nitric acid and cement it out with scrap copper. It comes down as a metal and melts without conversion. Still only 99% pure but the contaminants are easily dealt with in a silver cell. (lead is not)

Is your red acid nitric or schwerters solution? Schwerters solution is physically red, nitric acid usually comes with a red cap and it is clear.
 
Is your red acid potassium dichromate? Iron- or aluminium-dichromate are green. Lead dichromate would look yellow.
Normally potassium dichromate is only used to prove the presence of silver and not its purity.
Chromium chloride can also look dark green.. there are many possibilities.
 
i have a question. i keep reading up on how to refine silver and gold and keep coming across people saying that you need to use "70%" nitric acid, or in the case of silver "30%" nitric acid. is this a certain kind of nitric i need to purchase are they different? or do you make them that way by adding water or something? thanks for your replies. '

also is there a website i can purchase these chemicals from? if so please list it. thanks.

-Adam
 
I keep plugging this site and I'm sure this wont be the last time but... if you are paying dudadiesel prices for nitric acid you are better off buying from here. http://www.abprospecting.com
 
goldenchild said:
I keep plugging this site and I'm sure this wont be the last time but... if you are paying dudadiesel prices for nitric acid you are better off buying from here. http://www.abprospecting.com
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There's an error in their catalog. It says 1 gallon but it also says 7 pounds. Which is it? - it can't be both. I would imagine the 7# is right (sort of) because that's the way reagent grade usually is (was) packaged. I've never seen it come in 1 gallon jugs. A gallon of nitric weighs 11.8 pounds. Therefore, 7# would be 0.6 gallons. Therefore, at this weight, you are paying about $70/gallon plus shipping and that's way too much. There are cheaper deals out there. In the thread below, it says you can buy 5 gal of tech grade at $34/gallon, shipped! Terrace Packaging (same thread) might even have it cheaper. Unless you're using the nitric for fire assays, tech grade works equally well as reagent grade. Why waste your money?
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=48&t=9551&p=91655&hilit=terrace#p91655

Actually, the old, so-called, 7# jugs are obsolete, I think. That's what they called them when they held 5 pints (5/8 of a gallon - actually .625 gallons or about 7.4#). Nowadays, the reagent grade jugs hold 2.5 liters, or .66 gallons (7.8#). That's a little better ($63/gal plus hazmat shipping, which isn't cheap), but not good enough to warrant buying reagent grade from abprospecting, or anywhere else.

To be fair, the abprospecting price for reagent grade is very good but, except in rare cases, you don't need reagent grade.
 

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