# HELP please Ag Cu mess



## Anonymous (Sep 15, 2008)

I have several hundred ozs of minted silver shot which I dissolved in several gallons of nitric and water about 4 years ago. After reading about using copper to recover silver, I tried the process. However I discovered 2 problems, for 4 years an electric motor which I used to stir the mixture from the top had corroded from the chemical and there was a pile of material from the motor that had dropped into the tank making a nice little pile of debris in the bottom of the tank. The second problem was that I used dirty copper. I filtered the solution before cementing with the dirty copper. RESULTS: From 2 gallon of silver nitrate a pretty blue filtrate but lots of light green precip with silver powder mixed in it. I rinsed the mess many times with hot distilled water. QUESTIONS: 1. What would you experts do, how and what might be the precip. 2. I cemented the filtrate with clean copper pipe and obtained silver powder and blue green sponge which I rinsed until the fluid was clear. The blue green material and along with some silver powder remained. Any suggestions on what to do next. 3. I still have several gallons of silver nitrate solution left to recover the silver. Any suggestions to improve my process and results would be cretainly appreciated. I continue to read the forum. Thanks for all the helpful information!!!
marvin


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## Harold_V (Sep 15, 2008)

You might have success rinsing the cemented silver with dilute HCl. Allow the acid to remain with the silver for an hour or so. That may remove the traces of contamination. As far as the balance of the silver nitrate is concerned, filter it, or allow it to settle well, then decant before attempting recovery with (clean) copper. 

If your copper is not clean, subject it to hot dilute sulfuric. That will eliminate any oxides, but leave the copper behind. 

If you have provisions for melting, could be your metal will get improved slightly when melted. Use just borax as a flux, which will absorb a lot of the oxides that may not get removed. In any case, don't expect the silver to be of high quality. 

Depending on your ultimate goal, you may have to cast an anode and part the silver to bring it fine. It would serve perfectly well for use in inquartation as is. 

I would suggest you not discard anything. When you have gathered all of the solids (the wastes, not the cemented silver), run them in a crucible, adding soda ash and borax. You're bound to recover a considerable amount of silver, which will need to be parted with nitric and recovered with copper. Treat all solids, regardless of what you think they may be. You can do no harm unless you introduce aluminum. 

Harold


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## Anonymous (Sep 16, 2008)

Thanks Harold 
Any suggestions for the dilution portions for the HCL. I am now using new copper pipe which I got from the recyling center. I do not have melting capablities. When I filtered the silver nitrate none of the debris came into the filter paper. My assumption is that some of the debris became a nitrate and if so is there a way to test or wholesale treat for base metal?
Another question upon rinsing fine shiny silver powder floats on top. I have tried to capture this before pouring into the filter but unsuccessful. Any suggestions?
Thanks again


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## Harold_V (Sep 16, 2008)

mhwilson said:


> Any suggestions for the dilution portions for the HCL.


It's not critical. Maybe 50% water, 50% HCl. You should see an immediate change---and the solution will filter much better, assuming you have to. I expect it will settle well, then you can siphon and rinse a couple times. Do so until the rinse is clear. If you have a large Buchner, they work real well for the purpose. Once the silver loses the majority of its solution, it will start to shrink and crack. I tamped it down well, using the butt end of my pestle (it was quite large, made of ceramic). If you do have that luxury, you can then rinse the cement silver by vacuum. Goes a lot faster, and does a very good job. 



> I do not have melting capablities.


The waste material that comes from this project is sure to have value. If you intend to continue refining, incinerate the stuff and save it. If this is a one shot deal, you might try incinerating, then placing everything in a beaker and giving it a boil in HCl. Rinse well, then introduce a little aluminum and HCl, maybe 10%, which will reduce any silver chloride that may be present. In the end, you can recover any lost values, just don't toss the solids. Incineration is key here----it gets rid of a lot of the garbage that you don't want included. Depending on the source, the solids could contain other values, including gold. 



> When I filtered the silver nitrate none of the debris came into the filter paper. My assumption is that some of the debris became a nitrate and if so is there a way to test or wholesale treat for base metal?



When you dissolve silver, if it's pure, the solution is nearly colorless (leans ever so slightly yellow). If it has color of any description, it has contamination. What it is doesn't really matter-----although you may have a curiosity about what it may be. You can test for copper (ammonium hydroxide makes copper turn brilliant blue) or nickel (ammonium hydroxide, then a drop of DMG will turn brilliant pink if you have nickel), and you can even test for iron, but I don't recall the test from memory. It's discussed in Hoke's book, however. I don't know of a test for zinc----and lead will have self precipitated if it was present.

The HCl wash you give your material should dissolve any iron that's present, along with much of the copper oxides, and, I expect, any nickel. 



> Another question upon rinsing fine shiny silver powder floats on top. I have tried to capture this before pouring into the filter but unsuccessful. Any suggestions?



Yep! Incinerate before dissolving. That appears to be the one thing that no one understands, or perhaps they just don't want to hear it. Incineration prepares metals for processing. It's the easiest and fastest way to do so. When you dissolve metals that have been handled, you carry oils through the operation. The oils I'm speaking of are the reason you see silver floating. A rinse with HCl may help, but I don't know that it will. I always incinerated EVERYTHING before it saw the refining operation. It's a great habit to acquire. 

You can try to shoot down the floating silver with a wash bottle, but I expect that's going to be a slow process. Lye would likely eliminate the oil, but I don't know how you're going to make the transition from acid to base. 

Lou? GSP? 

Any comments in that regard? 

Harold


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## Anonymous (Sep 16, 2008)

Thanks for the great and rapid response. I see that I have some work to do. I'll let you know how things turn out.


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## peter i (Sep 19, 2008)

Harold_V said:


> ..........You can do no harm unless you introduce aluminum.
> 
> Harold




Why? 
Because he will precipitate any metal in the solution?


My personal nightmare is tin! I simply hate it! (I know that incineration might be an answer to that too!)


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## Lou (Sep 19, 2008)

Tin and aluminum are both BAD. Neither wash out well, and silver and aluminum always give me problems.


Lou


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## Harold_V (Sep 19, 2008)

Lou said:


> Tin and aluminum are both BAD. Neither wash out well, and silver and aluminum always give me problems.
> 
> 
> Lou


Indeed! Both of them complicate filtration beyond reason. 

Before I learned the art of washing difficult materials with HCl before dissolving the values, I had one batch of gold chloride, a liter in volume, take more than three days to filter. 

Afterwards, when I suspected filtration would be a problem, the values were collected after the nitric digest, incinerated, then boiled in dilute HCl. I would then fill the vessel with tap water, stir well and allow the solids to settle. Siphon off the solution, rinse once with water, stirring well and allowing the solids to settle again, then a last siphon. The values were then dissolved for precipitation. Filtration after this process was never difficult. 

Harold


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