# Silver Refining Chems or Tips



## dwt9999 (Apr 15, 2007)

I have been working with the silver I pull prior to processing for gold. I have been using the borax for a flux, does anyone know what the proper flux for silver is??

Any help would be greatly recieved!!

Thanks in advance!!

Lew


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## goldsilverpro (Apr 15, 2007)

Borax is the standard flux for melting silver.

Can you explain in more detail about what type stuff you are melting? Some types may require adjustments in the flux.


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## Harold_V (Apr 15, 2007)

Borax is the flux of choice. Anhydrous or borax glass (they're not the same thing, although chemically they are) are the easiest to work with, but more expensive. Plain Boraxo soap will work. 

If your objective is to reduce oxides, then you should include soda ash. It's best not included if your purpose is pure silver unless you have silver chloride present. 

Harold


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## dwt9999 (Apr 16, 2007)

I thank you for the information, I have been using the 20 mule borax as flux for the silver and gold I try to get....

I process just about everything through the Nitric acid prior to putting it into the AR. I was under the impression that it is best to get ANY silver out of the way prior to processing for gold.

So far all I have melted down are a few things that look copper instead of gold, and the silver I have tried to get out is very brittle! I am going to keep trying until I get something right, it is far to much fun to stop now!!

Thank you for your help

Lew


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## Harold_V (Apr 16, 2007)

dwt9999 said:


> I process just about everything through the Nitric acid prior to putting it into the AR. I was under the impression that it is best to get ANY silver out of the way prior to processing for gold.



If silver is alloyed with gold, it has the potential to prevent AR from dissolving gold if it's high enough in concentration. The silver chloride film that slowly develops is very hard, and isolates the alloy from exposure to the AR. It slowly builds as a green/gray coating on the metal in question, and soon the dissolving action grinds to a halt. You can literally boil your metal for days on end in AR once that happens and it won't dissolve. That's why it's so important to inquart alloys to get the gold down to 6 K, then remove it with nitric. 

If the silver content is low enough, the silver simply converts to chloride and falls free from the alloy as such. Gold alloy that is less than 10% silver will slowly dissolve, but it's far better to not have any silver present if possible. The biggest problem is that the chloride acts like a huge sponge and absorbs the gold solution. Endless washing reduces the content, but it's almost impossible to recover completely. If you properly recycle the wastes from filtration, you recover the vast majority of values in that operation, so they're not lost. 



> So far all I have melted down are a few things that look copper instead of gold, and the silver I have tried to get out is very brittle! I am going to keep trying until I get something right, it is far to muck fun to stop now!!



If you're tossing all kinds of junk in the pot, you may be introducing lead to the operation. I'm not quite sure how it affects silver, but it's death on the ductility of gold. You can minimize lead by not dissolving unknown items, but if you happen to get involved with lead, it has a peculiar property of precipitation on its own as lead nitrate if you allow the solution to cool. Once the lead precipitates, you can decant the solution and recover the silver with copper. Do you know about the testing solution that shows a blood red color when applied to silver? It can help you avoid dissolving things that are of no value. 

While being brittle isn't exactly a good thing, you shouldn't expect silver to come down cleanly. Recovered silver is a perfect candidate for a silver cell, but is highly unlikely to be of great quality. 

If your purpose in silver is to accumulate it, not just to sell it, store the silver until you have a good quantity, then you can build a simple silver cell and part it properly. It's really about the only way you'll come up with good quality, and if you work with any of the platinum group metals, you might be pleasantly surprised to find you recover them when you part the silver. You'll usually find gold traces as well. It's hard to make perfect separations. 

One comment. Because silver and gold can not be in any common acid solution together, they are extremely easy to separate. According to Sir T.K. Rose, a few silver atoms are known to behave as if they are gold atoms, so you might expect a trace showing in once refined gold. Otherwise, if you use good practice, your gold should be pretty much silver free. 

If you're using the AR process for gold, be certain to include a few drops of sulfuric acid in each batch. That precipitates lead as lead sulfate, which is then filtered off when you filter your gold chloride solution. It insures that you don't carry lead through the process. 



> Thank you for your help



Welcome. I hope some of this is, indeed, helpful. 

Harold


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## dwt9999 (Apr 18, 2007)

Harold_V wrote:


> Do you know about the testing solution that shows a blood red color when applied to silver?



I do not know of this test.

I have been processing a variety of items in the nitric and then into the AR. I believe that it has created my problem in the recovery stages, as the AR turns brown and I can not get anything to precipitate.

Thanks again for all the help, I will continue to ask for help as the need arises. As far as giving advice, so far all I can say is:
1) seperate what you intend to process
2) use low heat and circles when you melt
3) SAFETY FIRST!!!

Lew


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## Harold_V (Apr 18, 2007)

dwt9999 said:


> I do not know of this test.



I'll see if I can find my refining books, which are all in storage. I'll be able to give you the proper ingredients to make the solution. An ounce will last you a year or so unless you use it daily. It works great-----you shouldn't be refining without it. 



> I have been processing a variety of items in the nitric and then into the AR. I believe that it has created my problem in the recovery stages, as the AR turns brown and I can not get anything to precipitate.



I harp continually about Hoke's book. Do you have it? Have you read it? Do you understand about not having excess nitric in solution before precipitating? You may be doing several things wrong. Sit back, take a deep breath, and take a look at what you're doing. Try to read Hoke's book, even if you use urea (I never used it--I evaporated and wouldn't have it any other way). Above all, don't toss anything. As long as you have the solutions, you can make a recovery-----you just have to come up with what works. If all else fails, you can recover everything on scrap steel and start over. 

If I'm successful in finding my books, I'll post under a new heading, probably one titled Silver testing solution, or some such. Watch for it. 

Harold


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## goldsilverpro (Apr 18, 2007)

The silver test solution is potassium dichromate plus nitric acid. The first gold testing kit I bought came with a small vial of potassium dichromate, to be mixed with nitric. Here's how to mix it - solution #1. Shor uses it to test base metals also.

http://shorinternational.com/TestGoldMakeSolution.htm


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## Harold_V (Apr 18, 2007)

Thanks for that, GSP------I spent an hour last night going through boxes looking for the right information. Came across a few metals books and other information, but not what I was looking for. Now I can relax!

As you said, there's instructions for using the testing solution for base metals as well, but a dropping bottle, or better yet, a bottle with a dauber that contains plain old nitric acid is better suited. The dichromate color tends to alter the color reactions enough to be confusing on occasion. I kept both solutions at the ready, although as time goes on you find you need them less and less. It's amazing how the eye can distinguish German silver from silver, for example.

Harold


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## jimdoc (Apr 18, 2007)

Page 22 of CM Hoke's Testing Precious Metals mentions the dichromate
test and how to make it.


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## dwt9999 (Apr 19, 2007)

Thank you all for the information. The Hoke book, is that the one that goes for several hundred on ebay?

I have looked at it but not get it yet.

I would say I still have a lot to learn.

Thanks again!!

Lew


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## Harold_V (Apr 19, 2007)

dwt9999 said:


> Thank you all for the information. The Hoke book, is that the one that goes for several hundred on ebay?



The correct title is Refining Precious Metal Wastes, C.M. Hoke. GSP posted a source for the book where it's available for about $75 ------it's on the board somewhere. Perhaps he will refresh everyone's memory. 

Rather than edit my words, I'll make an addition here. The book in question is not the book I named. Sorry for that. I have not seen the book that has the testing solution information. That particular book, written by the same author, revolves around testing for precious metals, not refining them. There is adequate information on testing in the book I mentioned, and is the book of choice if you desire to learn refining. Both books would be an excellent addition to your library, from all indications.  



> I have looked at it but not get it yet.



I learned refining from that very book. I took no chemistry in high school, and have no formal education. The book is outstanding in conveying useful information to a person that has little or no chemical understanding. If you buy the book and learn what it has to offer, you should become a competent refiner-----even if you don't have any other sources of information. Damned few books on the market can make that claim. 



> I would say I still have a lot to learn.



I refined for gain for over ten years. There was so much I hadn't learned when I sold the business that it's embarrassing. You'll never learn it all, but you can become very good at your little niche, assuming that's your desire. Luck!

Harold


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## jimdoc (Apr 19, 2007)

No I just picked one up for $11 on Ebay. It is calledTesting Precious Metals Identifying-Buying-Selling copywright 1946
It says the first edition was originally published in
The Brass World-Plating-Polishing-Finishing in case you
can find that.


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## jimdoc (Apr 19, 2007)

Action Mining has the other book that Harold mentioned
for $89. You should get their catalog and check out their
other books too. Youcan download it online or call and ask
for one to get mailed.


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## goldsilverpro (Apr 19, 2007)

You can get Hoke's, "Refining Precious Metals Wastes", here for $74 - fifth from the bottom.

http://www.ipmi.org/publications/index_non.cfm


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## goldsilverpro (Apr 19, 2007)

jimdoc,

Is the Testing Precious Metals by Hoke? Is it the 3rd edition? If so, you got a real deal. They usually go from $40 - $80. They want $75 for the one presently on eBay.


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## jimdoc (Apr 19, 2007)

Yes the third edition. It says that the first edition was in Brass World,
I guess that was a magazine? The top edge of the binding is missing
a piece, I guess that is why I got it cheap.


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## austexjwlry (Jun 10, 2007)

We've been casting and fabricating silver jewelry for 16 yrs now. Borax for melting is great! Our favorite commercial flux for silver soldering is "Batterns".You can make your own by adding boric acid to denatured alcohol until it quits dissolving and makes a thin paste.We've used 20 mule team borax, works well.You can buy borax really cheap from ceramic supply shops along with bone ash (for carbon content), soda ash by the lb or 50lb etc. They use them and lots of other chem. for glaze preparation.

If you have refined your silver to fine you don't need flux!

Wayne


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