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extracting silver from galena

Posted by Mark & Linda Mahlum  
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Mark & Linda Mahlum August 13, 2008 04:23AM
Does anyone know of a safe way to extract silver from a galena ore? I am in possession of a couple of pounds of high grade (I think) ore.

Mark
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Sebastian Möller August 13, 2008 09:06AM
Hello,

The way used over centuries was:

1. heating the ore to remove the sulphur (Attention: toxic and acidic exhaust fumes, very bad for the environment)
2. oxidizing the lead (heating at maximum contact with air in shallow pans)
3. getting the remaining silver from the bottom (in Germany called Blicksilber ("silver glance").

The three products you will get are sulphuric acid (or just SO2 or SO3 fumes), lead oxide (massicotite) and silver.

Another way would be to solve the galena in acid or a solution, then putting a coal (as cathode pole) and a copper (as anode pole) stick into the solution. If you put the cables at a car battery, the silver will get attracted to the copper stick. This is used as galvanic elements for coatings of e.g. Zinc on iron and for refinement of copper or silver.

Both ways aren't really save.

Regards,

Sebastian Möller
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Colin Robinson August 20, 2008 10:22PM
Would it be worth the trouble for the amount of silver you might get?

The North Pennine galena from England carried silver values from zero to maybe 40oz per ton but typically 3 to 8. It was worth extracting the silver only because they were dealing in huge tonnages of lead ore and didn't have to worry about environmental health officials breathing down their necks.

As Sebastian pointed out, the process is rather nasty and not the sort of thing to be doing in your back yard
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Howard Heitner August 21, 2008 02:26AM
There is an old method, called the Parkes process, which was used to separate silver (and gold) from lead. The argentiferous galena is first reduced to metallic lead, Then zinc is added to the molten lead, The silver is much more soluble in the zinc. The zinc rises to the surface, taking most of the silver with it. The silver/zinc alloy is then roasted to recover the silver. I don't think that the investment in the necessary equipment would be justified for treating a small amount of ore.
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Mark & Linda Mahlum August 21, 2008 02:47AM
The grades in that old mine were 250-300 Oz of Ag per ton. It's not about the value of the silver, it's the discovery that matters. I won't be building a smelter in my backyard, I just want to recover a small amount of silver for the fun of it. I have a backyard of thousands of Colorado acres, but I don't want to contaminate it.

Mark
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Don Saathoff August 21, 2008 03:49PM
Hello Mark....There is a process used by collectors here in New Mexico which does not require a great deal of equiptment or dangerous procedures. It'll take me a day or two to find the printout of the process (and I'm a VERY slow typist!!!) so email me at auagte2@comcast.net and I'll return the email with an attachment.

Don S.
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Joseph Freilich August 21, 2008 05:31PM
hi....those vapors are very dangerous...it is probably not worth the risk...Joe
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Volker Betz August 21, 2008 06:52PM
Hello,

if you want to do on a small scale use a blow pipe. See:

http://www.mindat.org/book_details.php?id=20. The Sulpurdioxide and lead vapours are still unhealty.

The blowpipe was used to essay the silver content od lead ore in the old days.

Volker
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Jesse Crawford August 21, 2008 10:12PM
A reasonably safe method is to precipitate the silver as a chloride from acid solution, then reduce the silver chloride.. Stepwise: Dissolve the specimen in nitric acid. add sodium chloride and collect the white precipitate (a mixture of lead and silver chloride) on a coffee filter. Then add water to the precip and boil. Do this a few times. Hot water dissolves the lead chloride and leaves the silver chloride as an insoluble white material. Then dry the silver chloride and mix it with charcoal and borax. Heat the mix to red heat for several minutes in a crucible. If all goes well, you'll get a nice little button of silver. If the original sample has any mercury in it, this will come off as a vapor when you heat the crucible, so don't sniff it. Have fun.

Aloha,
Jesse
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Alysson Rowan August 23, 2008 03:47PM
Jesse Crawford Wrote:
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> A reasonably safe method is to precipitate the
> silver as a chloride from acid solution, then
> reduce the silver chloride.. Stepwise: Dissolve
> the specimen in nitric acid.

Just a reminder that dissolving any sulphide mineral in acit will liberate Hydrogen sulphide (rotten eggs smell). This gas is about 10 times as dangerous as cyanide gas - it is just as toxic with the added problem that at above a few parts per million level in air, it behaves as an anaesthetic, and you can no longer smell it.

This process should be carried out in a fume-cupboard or the open air.

The cupellation process was used to assay silver as well as extract it.

Smelt the lead/silver ore. Continue to heat with zinc (at about 10 of lead to 1 of scrap zinc). Skim off the zinc (if you let the whole lot cool together, you may be able to liberate the zinc using a hammer - the point ofd contact can be quite fragile.

Now heat the zinc in an oxygen-rich flame on a bed of bone ash. He zinc is absorbed by the ash, and at some point the bead of metal will blick, that is suddenly become very bright. This is now pure silver (around 99.98%, if the galena doesn't bear too many other zinc-soluble impurities)

Remember that lead vapour is toxic, and so is the sulphur dioxide liberated in smelting sulphide ores.

You may like to pre-roast your ore outside on a charcoal heatsource to drive off a lot of the sulphur, and any arsenic (smells like garlic, and is, guess what, hightly toxic ;) ).

Good luck with your assay.

□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□
When you invited me to see your etchings, I didn't expect to
see so much degraded quartz. Really.
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Peter Haas September 02, 2008 03:41PM
"Just a reminder that dissolving any sulphide mineral in acit will liberate Hydrogen sulphide."

Not, if nitric acid is used, which will oxidize the sulphide to sulphate.
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Alysson Rowan September 02, 2008 04:11PM
Peter Haas Wrote:
-------------------------------------------------------
> "Just a reminder that dissolving any sulphide
> mineral in acid will liberate Hydrogen sulphide."
>
> Not, if nitric acid is used, which will oxidize
> the sulphide to sulphate.

True. But there again, most folks use hydrochloric acid because of the easier availability.

By the way (and I know Peter knows better) ....

Don't try to use sulphuric acid on Galena - the reaction is halted almost immediately due to the formation of insoluble lead sulphate. (I remember a friend trying this during a chemistry class, and wondering why the sulphide didn't dissolve).

Using Nitric acid, you do need to be careful as the acid tends to get quite hot, and is liable to boil.
Of course, by dissolving argentiferous galena in nitric acid amd then filtering, the addition of hydrochloric acid to the clear solution will yield a precipitate of silver chloride which can then be filtered, washed, dried and assayed - you can even reduce this to metallic silver (I used to recover silver from laboratory waste using pyrogallic acid and white sugar but there are other approaches.)

Now, how would we proceed with auriferous ore samples, I wonder?

□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□
When you invited me to see your etchings, I didn't expect to
see so much degraded quartz. Really.
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Donald Peck September 03, 2008 03:00PM
After dissolving galena in HNO3, adding HCl will precipitate BOTH silver chloride and lead chloride. Thre lead chloride can be leached out by filtering the precipitate off and boiling it in water and discarding the solution. The remaining precipitate should be boiled a couple of times more, discarding the solution each time. Silver chloride is essentially insoluble in hot water, lead chloride is fairly soluble. The remaining precipitate of silver chloride can be dissolved in ammonium hydroxide, which will leave any mercury I chloride behind, and then the silver can be reprecipitated as a chloride from the clear solution. This is fine for a qualitatve, or even quantitative test, but I doubt it is practical as a method for winning silver.
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Don Saathoff September 04, 2008 04:13AM
Donald Peck's procedure is the best for seperating small quantities of silver from galena....and the safest!!! You will still have to use heat to reduce the silver chloride to silver

Don S.
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Pedro Lavrador November 07, 2008 07:01PM
May anyone of you kind Sirs/Madams explain to me how to extrac silver from wacth batteries (they contain silver oxide)?
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naeem March 30, 2012 05:44PM
Dear
I purchased 10 tons of Galena ore (lead ore)
but unfortunately i did nt melt it
I want to use lead for acid battery
Please send me some procedure how i get lead from it ore?
Thnaks
naeemjumani@ymail.com
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auagte2@comcast.net April 23, 2012 10:33PM
Don Saathoff Wrote:
-------------------------------------------------------
> Hello Mark....There is a process used by
> collectors here in New Mexico which does not
> require a great deal of equiptment or dangerous
> procedures. It'll take me a day or two to find
> the printout of the process (and I'm a VERY slow
> typist!!!) so email me at auagte2@comcast.net and
> I'll return the email with an attachment.
>
Reference to your mexico process if you can send the attachment to me i will be thankful to you.

Regards

Flocini

flocini@yahoo.com
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Christian Auer April 24, 2012 06:39AM
Sebastian mentioned the silver glance (Silberblick). That reminded me of a beautiful xylographic I own.
Here`s a pic from it http://www.mindat.org/photo-461547.html.
Hope you like it as I do.
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Jkg June 29, 2012 02:24AM
I have 200lb of ore that has 7.4oz ton Au and 26oz ton Ag. Here is the problem that I have. The ore has lead, zinc, moly, and some copper. I have put it in my furnace with borax, silica, and carbon. The end was a metal button the same size as the Origanle charge. I hit the button with a hammer to brack off the flux and the metal button powdered. My question is 1) how do I get the moly out, and 2) dose any one have a good flux that would help in the separation of the Au and Ag. Please Email with any advice.
Mrexploration@gmail.com
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Alan Barnes (2) June 29, 2012 09:21AM
If you put some hydrogen peroxide in with the galena and nitric acid solution it speeds things up quite a bit. Put the nitric acid in first, then the peroxide. Or, fi you could get hold of it, you could use ziconium nitrate in water followed by the addition of hydrogen peroxide. This way, zirconium(IV) nitrate hydrolyses in water to give zirconyl nitrate and nitric acid so nitric acid is generated in situ which makes it a bit safer.

Alan
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Holger Klapproth June 29, 2012 04:39PM
Hi everyone !

I guess some people here have never seen what happens when a mixture of hydrogen peroxide and nitric acid goes bang....

My really sincere advice is: never ever mix such dangerous chemicals. I worked in a company which had a process step where acidic peroxide solutions were used. And I know how people look like after accidents. Nitric acid is already very bad but adding hydrogen peroxide to it is calling for accidents. These solutions can spontanously start to boil and one drop of the liquid getting in the eyes means blindness. An experienced person may handle small amounts in a fume hood but using this for bulk treatment is a hazard. And also if you try to buy such amounts of nitric acid and or peroxide the secret services will come after you thinking you want to build explosives.

And then afterwards to have to get rid over a lot of contaminated liquid..... very expensive if you follow the regulations - shame on you if you do not.

Peter posts a lot of warnings - listen to him - he usually is right
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Alan Barnes (2) June 29, 2012 05:37PM
Holger,
If you mix fairly concentrated nitric acid with hydrogen peroxide then yes, you are asking for trouble. However, if you generate nitric acid in situ as I suggested from zirconium nitrate as I suggested then the nitric acid can be very dilute and yet still dissolve both lead and lead sulphide. Its one of the technique used in oifields that suffer from lead or lead sulphide scaling. The solutions are very dilute so that all of the scale is dissolved and the waste is then pumped up to the surface. Its a cheap and effective method.

ALan
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Reiner Mielke April 04, 2014 04:45PM
Hello Jkg,

What is the mineralogy of your ore? Normally you separate as many components before you smelt it, now that you have melted it all you essentially have a hell of a mess. There is no flux to separate Au and Ag you normally do the separation chemically with something like nitric acid. You could try dissolving your metallic portion in nitric acid and then precipitate the silver out as a chloride as discussed in this thread. As for the gold it should be in the residue which you will have to remelt with some lead oxide and flux to collect the gold. Then dissolve the button from that in nitric acid to get rid of the lead. Any moly should have either been dissolved in the first step or come out with the flux in the second step. Good luck, without knowing the mineralogy of the original I am not sure what will happen.
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t.wiggins December 22, 2014 08:30PM
Can you email me the technique please. Does it work on Pyrite ore also ? Thank you.
Tommy
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Reiner Mielke December 22, 2014 10:11PM
Assuming you are refering to extracting silver from galena this sort of thing is what you would do with very small quantities of mineral, it is not economical for large amounts. See a book on metallurgy for how best to treat large amounts of galena to recover the silver.
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Malka May 27, 2015 08:11AM
Hello
I wondered if you managed to assay some silver from galena in the end?
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boniface nzom November 13, 2016 02:32PM
SIR,I AM ELATED TO GET YOUR INFORMATION ON EXTRACTION OF SILVER FROM GALENA.I WILL APPRECIATE GETTING INFORMATION FROM YOU ON AN EASIER METHOD TO EXTRACT SILVER FROM THE GALENA.THANKS. BONNIE.,LAGOS.
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Piet van Kalmthout November 13, 2016 03:03PM
Dear Mark,

In Greece already from 3000 BC (!) the silver extraction out of Galena took place. Possably the ancient Greecs did invent the method.
You can read the method in our book: Laurion the minerals in the ancient slags. See also: Http://pietvankalmthout.ruhosting.nl/laurion

with regards

Piet van Kalmthout
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