# Precipitate silver in aqua regia ?



## Noxx

Hello,
Is there a way to precipitate silver in an Aqua Regia solution ? Either before or after gold.
Thanks


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## Anonymous

Noxx said:


> Hello,
> Is there a way to precipitate silver in an Aqua Regia solution ? Either before or after gold.
> Thanks



The scientific answer is yes, there is always a method to attempt this. The difficulty comes in justifying costs versus results. What is your goal?

a man named Sue


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## Harold_V

Sue said:


> Noxx said:
> 
> 
> 
> Hello,
> Is there a way to precipitate silver in an Aqua Regia solution ? Either before or after gold.
> Thanks
> 
> 
> 
> 
> The scientific answer is yes, there is always a method to attempt this. The difficulty comes in justifying costs versus results. What is your goal?
> 
> a man named Sue
Click to expand...


*Nonsense!!!*

One can not have silver *in solution *in AR. Any silver present as a nitrate will immediately precipitate as chloride when AR is introduced. That's why gold and silver as so easily parted. 


Harold


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## Noxx

OK ! I understand. Thanks


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## Anonymous

Harold V,

It would appear you just agreed with me. 

Are you now saying that silver which you identified correctly exists as in AgCl compound as a precipitate, due to the presence of HCl in a muriatic nitric aqua regia, cannot be isolated?

The question before the forum is:


> Is there a way to precipitate silver in an Aqua Regia solution



I said it could. You said it could. 

So, why, when I say so, you label it as "nonsense" but when you say so, it is not nonsense? Your response is not a logical response but an emotional one it would appear.

My point remains: economics.

a man named Sue


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## Harold_V

Sue said:


> Harold V,
> 
> It would appear you just agreed with me.
> 
> Are you now saying that silver which you identified correctly exists as in AgCl compound as a precipitate, due to the presence of HCl in a muriatic nitric aqua regia, cannot be isolated?
> 
> The question before the forum is:
> 
> 
> 
> Is there a way to precipitate silver in an Aqua Regia solution
> 
> 
> 
> 
> I said it could. You said it could.
Click to expand...


No, I did not. I said you can't have silver in solution in AR-----that is not possible. You can have silver and gold in solution in cyanide, but that's not the topic of discussion.. 

Before you can precipitate silver from a solution, it must be *in* the solution. It is not in solution in AR, and that was the question. That silver chloride can be separated from gold chloride is a no brainer. I did that routinely for more than 20 years, as does anyone that filters their gold chloride before precipitation. Total separation, however, is almost impossible. I'll provide my years of practical experience as the reason, below:

When you allow silver to progress to the stage of dissolving your gold in AR, it will usually be in the form of silver nitrate. When silver chloride is formed, a result of introducing AR to the gold, it is hugely voluminous as compared to elemental silver, and acts like a sponge to absorb gold chloride. The silver chloride will hold a respectable amount of gold chloride after filtration, even after washing well. It is not lost, but recovered in subsequent operations, but if you're trying to account for all the gold in a given lot, you come up short. 

Harold


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## Bluebloomer

I hope it's ok to bump this topic, but according to your last post I have a follow up question; 

If the silver chloride consumes some of the gold, what would be the best way to recover the gold ? Will the gold be pushed out during the conversion process of AgCl to metallic silver, or will that conversion produce a silver contaminated with gold alloy of sorts ?


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## nickvc

It's not so much that the chloride consumes gold it's that the chloride powder will hold onto some of the gold solution, not much if you rinse well on a powered filter, but some maybe 1/2% of the total depending on the volume of silver chloride. That's why using a silver cell is recommended, it recovers the gold and any PGMs that may have been present in the slimes. It's also accepted that AR can hold small quantities of silver in solution that's why adding water is recommended as when it dilutes the solution the silver will drop out as chloride and be recovered on the filter.


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## g_axelsson

I don't understand exactly what you mean with silver chloride "consumes gold".

The most commonly reason that we get gold chloride with our silver chloride precipitate is when dissolving gold with small amounts of silver in the alloy in AR. The silver is then turned into silver chloride and we can both have small particles of metallic gold encased in silver chloride as well as gold chloride mechanically trapped in the silver chloride.

The gold chloride can be washed out with rigorous washing but the solid gold particles will follow the silver chloride. When we turn the chloride back into metal the gold will already be there and contaminate the silver. A silver cell is a good way to increase the purity of the resulting silver metal.

The art of refining is to know which reactions and processes to use to get as pure product as possible with the least amount of work and chemicals. No process is 100% effective, side reactions and mechanical processes more or less works against the higher purity. The good refiner learns how to use that and minimize the side reactions.

Have you read Hoke yet? Done the acquaintance experiments yet? Page 36 to 38 is relevant to this question.
http://goldrefiningwiki.com/mediawiki/index.php/Hoke_acquaintance_experiments

The most common mistake by a newbie (I've done it myself several times) is to use too much or too little of chemicals or time. This will increase the side reactions and suddenly we got problems we never expected. Lack of experience easily confuses and makes a bad situation even worse.
Here reading and learning what could and should happen is a great way to prepare before doing a process for the first time and the forum is an unique place for that.

Göran


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## justinhcase

As even silver chloride(AgCl) is soluble in H2O I find I get a little AgCl carried over in my AR.
Even on second run Au after reduction I get a small amount of white precipitate once I re-hydrate the reduction.
For some reason a concentrated Gold Chloride solution keep's this small amount of impurity's in solution until I add a bit more water.
Which seems counter intuitive as the rest of the low solubility impurity's drop out with out the re-hydration.
So Technically you can precipitate silver out of AR but as AgCl and only in very small amount's .
Or is that to fine a line to be considered a precipitation,it is more of a release of trace impurity's rather than a true compound precipitation.


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## Palladium

justinhcase said:


> As even silver chloride(AgCl) is soluble in H2O I find I get a little AgCl carried over in my AR.
> Even on second run Au after reduction I get a small amount of white precipitate once I re-hydrate the reduction.
> For some reason a concentrated Gold Chloride solution keep's this small amount of impurity's in solution until I add a bit more water.
> Which seems counter intuitive as the rest of the low solubility impurity's drop out with out the re-hydration.
> So Technically you can precipitate silver out of AR but as AgCl and only in very small amount's .
> Or is that to fine a line to be considered a precipitation,it is more of a release of trace impurity's rather than a true compound precipitation.



http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=22433&hilit=silver+chloride#p235367


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## solar_plasma

I like your explanation in your link, Palladium!

Here I posted some aditional infos about AgCl and solubility, even though this is not important for the practice, it might be interesting to know for some.

http://goldrefiningforum.com/phpBB3...=21519&p=222326&hilit=solubility+agcl#p222326


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## Geo

Björn, I have found that acid concentration also is a factor in how much silver can remain in solution and as you said, temperature is a huge factor. If there is a large amount of silver in the starting material,there will sure to be some silver follow the gold all the way to the final wash and melt.


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## Anonymous

Geo I too used to have this problem until I followed some advice that Lou gave me. I use one set of AR as a recovery process, don't dilute it, follow his wash process and then I'm left with powder that will have some small amount of silver there. Then I use AR again to refine the gold. 

This true refine process is much lower volumes of liquid so diluting it three times to get the AgCl to precipitate out doesn't involve large amounts of waste. I've learned over the last three years to not treat the first dissolution in AR as a refine- merely a recovery process. 

Excellent filtering using good papers and a Buchner funnel is the way forwards for getting rid of this pesky powder.


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## g_axelsson

In concentrated AR or just hydrochloric acid some silver chloride is soluble. This is because of the high concentration of chloride ions in solution.

So the solubility drops when you add water as the chloride ion concentration drops, just as copper II chloride does.

On http://www.saltlakemetals.com/Solubility_Of_Silver_Chloride.htm you can see various liquids and how much silver chloride can be dissolved in them.

Göran


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## justinhcase

g_axelsson said:


> In concentrated AR or just hydrochloric acid some silver chloride is soluble. This is because of the high concentration of chloride ions in solution.
> 
> So the solubility drops when you add water as the chloride ion concentration drops, just as copper II chloride does.
> 
> On http://www.saltlakemetals.com/Solubility_Of_Silver_Chloride.htm you can see various liquids and how much silver chloride can be dissolved in them.
> 
> Göran


Thank you very much for the explanation.
Very interesting,I have been curious about the mechanism. 
Much obliged.


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## Anonymous

If you filter gold powder in a Buchner funnel using gravity with concentrated HCl it will take AgCl through with it. (Not my process, I am quoting Lou, and it works)


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## goldenchild

spaceships said:


> If you filter gold powder in a Buchner funnel using gravity with concentrated HCl it will take AgCl through with it. (Not my process, I am quoting Lou, and it works)



The key here is that it must be very concentrated. The type of concentration that can hold the small amounts of silver in solution in aqueous form (as discussed above). Even then I think you would be hard pressed to get all the aqueous silver to filter down unless dealing with very small amounts of gold sponge. Getting the silver to filter through when adding HCL to inquarted gold sponge would be impossible as adding HCL would instantly ppt silver chloride on contact.


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## nickvc

You can chase your tail over this but you can remove any silver in the precipitated powder fairly easily, personally I can't be bothered as I get the same payout for 99% as 97% Au, adding water in the recommended volumes will remove 95-99% of the silver, want better use the wash techniques described here on the forum, still not happy refine it again Nile still in powder form using a different method.


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## goldenchild

nickvc said:


> You can chase your tail over this but you can remove any silver in the precipitated powder fairly easily, personally I can't be bothered as I get the same payout for 99% as 97% Au, adding water in the recommended volumes will remove 95-99% of the silver, want better use the wash techniques described here on the forum, still not happy refine it again Nile still in powder form using a different method.



Most anywhere you won't get the same payout for 99% vs 97% purity. In your case it sounds like you should actually be aiming for 97% and nothing more.


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## justinhcase

Such small amount's of AgCl are very easy to wash out with ammonia so no need to fuss.
But it seems to be the correct answer for the initial question."Is there a way to precipitate silver in an Aqua Regia solution ?"
Yes there is but in such small quantity's it is technical interesting but impractical for any worth while recovery.


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## Geo

I believe Nick is saying he gets paid for the gold content whether it's pure or not. I really don't think he meant to say they paid the same price for 97% as 99%. If you get paid for the gold content, the purity is not a big issue unless the lots are so big there's a hefty handling charge involved.


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## saadat68

Hi
If we leach silver or silver compounds with AR and then filter residue. How much silver or silver chloride will be in solution ? nothing ? 
Can you say in percent for example ?

Thanks


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## goldsilverpro

saadat68 said:


> Hi
> If we leach silver or silver compounds with AR and then filter residue. How much silver or silver chloride will be in solution ? nothing ?
> Can you say in percent for example ?
> 
> Thanks


This is for dissolving gold that contains silver, like karat gold. Leaching silver or silver compounds may or may not produce the same results and this probably depends on whether the silver is finely divided or not, the temperature, and the specific silver compound. However, when cooled to room temp, I doubt if the numbers will exceed those given below, in any case.

With full strength AR (no added water), about a gram or two per liter at room temperature. With ANY dilution (e.g., when filtering and then rinsing), some of this dissolved AgCl will precipitate. If diluted to 25% AR with 3 parts water, about 98% (maybe more) will precipitate. That is why I always dilute AR 3 to 1 before filtering. Far more effective in eliminating silver from the solution (proven), simpler, and less messy than using ice. As a bonus, the dilution tends to reduce the effect of excess nitric and makes the gold reduction go smoother. Even though I sometimes get a little sloppy and go overboard with my nitric usage, since I started diluting 3:1 I can't remember ever having to treat the standard AR solution in any way for excess nitric (evaporation, sulfamic acid, etc) before dropping the gold with a sulfite. The only exception was when using so-called reverse AR (50% nitric).

I once experimented with all of this, but that was almost 50 years ago. I can't remember the exact numbers, but what I've given above are close.


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## tesaygo

Yes! Try to put salt (NaCl) on your aqua regia with dissolve silver(Ag). 

During pouring of salt on aqua regia, white powder will appear and soon will be settle under, that white power is silver collect them. Then cook it. 

Best regards,
Jason


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## Topher_osAUrus

Maybe it's just me... But, I dont think I would cook AgCl. I would definitely convert it to metallic silver first. Or, at the very least, silver oxide.

Cooking silver chloride will not only poison you, but create losses, and (obviously) dry it out. So when you do decide that the process didn't work as you hoped, converting it will be that much more of a pain to do. It's not impossible, but it will make you resent yourself for making something thats inherently so cheap, so difficult to reclaim.


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## goldsilverpro

Topher_osAUrus said:


> Maybe it's just me... But, I dont think I would cook AgCl. I would definitely convert it to metallic silver first. Or, at the very least, silver oxide.
> 
> Cooking silver chloride will not only poison you, but create losses, and (obviously) dry it out. So when you do decide that the process didn't work as you hoped, converting it will be that much more of a pain to do. It's not impossible, but it will make you resent yourself for making something thats inherently so cheap, so difficult to reclaim.



I took it to mean cooking it in liquid.


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## Topher_osAUrus

goldsilverpro said:


> I took it to mean cooking it in liquid.



Hopefully so, maybe tesaygo can give some more detail on what he meant for our friend saadat68. If not for anything else, but to help alleviate some of the questions he will undoubtedly have.


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## Lino1406

To convert silver chloride, stable material boiling at 1550C, to silver you can "cook" it with iron (e.g. nails), taking care for the iron chlorides that evolve


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## ARMCO

If after you have dissolved everything and you're ready to filter. Chill the AR with tapwater ice cubes. Let chill and settle and the silver will have precipitated out to the bottom.


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## ARMCO

tesaygo said:


> Yes! Try to put salt (NaCl) on your aqua regia with dissolve silver(Ag).
> 
> During pouring of salt on aqua regia, white powder will appear and soon will be settle under, that white power is silver collect them. Then cook it.
> 
> Best regards,
> Jason




I'm not sure what is meant by "cooking" the silver chloride mentioned here. 

My recommendation would include a number of things. 
1. Any time you're going to try something you haven't yet done, like putting salt in your AR, Take a very small sample and try it on that sample first so if something goes awry, you haven't messed up your whole batch.
2. Carefully filter your AR, the silver chloride will not go through a proper filter and that can be one way for you to collect it.
3. look up Lye method of converting your silver chloride. When you have clean silver chloride in a beaker or some other container, add regular household LYE (no additives, just plain lye - sodium hydroxide) and while stirring (safely, you have to decide how and with what equipment you'll be using, eg magnetic stirrer?) and your white silver chloride will convert to black silver oxide. Then using some sort of sugar (Karo syrup, dilute it a little to thin it or use as is) and the silver oxide will convert to metallic silver. It will appear dark but have a shiny gray appearance. The sugar will carmalize and be very brown also so don't let that fool you. Dilute/wash that, let settle, repeat several times until clean and you can melt that powder. It can be very pure but that depends on your technique. Ive done it a number of times and it works. Those reactions create ALOT of heat and steam so use caution and proper beakers/containers/equipment.

Good luck.


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## ARMCO

Topher_osAUrus said:


> Maybe it's just me... But, I dont think I would cook AgCl.
> 
> Boiling your aqua regia with gold in it (AgCl) WILL cause significant losses. I know. I've done it. It boils it right out of the beaker.


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## ARMCO

Harold_V said:


> Sue said:
> 
> 
> 
> 
> 
> Noxx said:
> 
> 
> 
> Hello,
> Is there a way to precipitate silver in an Aqua Regia solution ? Either before or after gold.
> Thanks
> 
> 
> 
> 
> The scientific answer is yes, there is always a method to attempt this. The difficulty comes in justifying costs versus results. What is your goal?
> 
> a man named Sue
> 
> Click to expand...
> 
> 
> *Nonsense!!!*
> 
> One can not have silver *in solution *in AR. Any silver present as a nitrate will immediately precipitate as chloride when AR is introduced. That's why gold and silver as so easily parted.
> 
> 
> Harold
Click to expand...



How did you put it? NONSENSE!! Lol

Actually, I've had some silver in the bottom of the AR like you said, but that was usually left there because of passivation. But depending on how much silver is present, if you chill the AR with tapwater ice cubes, you will have any silver in solution precipitate out. I certainly have. I don't know why that happens, because when you dissolve silver in nitric acid, one way to precipitate the silver is to add HCl and it will precipitate it out as silver chloride. That IS one way I do it (bleach does the same thing and can be cheaper). So I don't know why, but that has happened to me.


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## anachronism

ARMCO said:


> Topher_osAUrus said:
> 
> 
> 
> Maybe it's just me... But, I dont think I would cook AgCl.
> 
> Boiling your aqua regia with gold in it (AgCl) WILL cause significant losses. I know. I've done it. It boils it right out of the beaker.
Click to expand...


You can boil AR without having "significant losses" quite easily.

Edit for context.


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## ARMCO

Are you speaking theoretically or from actual experience? I ask this respectfully. I HAVE had the experience of significant losses and have also been told by others that can happen, actually told WILL happen if you boil AR and I have never done it again. Everything I've looked up also strongly discourages boiling in favor of evaporation due to this occurrence as well. 

As I said, maybe your experience has been different, but mine has been as stated above.

Also, if you would be willing, could you check out my "Too much SMB" post. I would sincerely like to hear your thoughts. 

This is my first time on a refining forum

thank you


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## ARMCO

justinhcase said:


> As even silver chloride(AgCl) is soluble in H2O I find I get a little AgCl carried over in my AR.
> Even on second run Au after reduction I get a small amount of white precipitate once I re-hydrate the reduction.
> For some reason a concentrated Gold Chloride solution keep's this small amount of impurity's in solution until I add a bit more water.
> Which seems counter intuitive as the rest of the low solubility impurity's drop out with out the re-hydration.
> So Technically you can precipitate silver out of AR but as AgCl and only in very small amount's .
> Or is that to fine a line to be considered a precipitation,it is more of a release of trace impurity's rather than a true compound precipitation.




Ah!, I should have read a little more before I posted. You just explained why I have gotten the results I described. Thank you


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## Topher_osAUrus

Ive boiled AR and didnt suffer great losses as well.(when I had to, dissolving platinum)
I simply use a watch glass, and a piece of fiberglass insulation balled up to put in the lip of the beaker, which soaks up any of the values that try to eek their way out of the vessel.

Not having the reaction vessel more than 1/3 full helps a great deal as well.

I dont usually heat it that strongly, but I always use the fiberglass plug, as even the bubbling from a regular dissolution of gold likes to find its way out of the beaker lip just as much.

------

And, it may or may not be "technically" a precipitation, but the AgCl when in the gold chloride solution is held in as AgCl2, when diluted it becomes turbid and slowly falls to the bottom of the beaker. 
This "flaky condition" AgCl is oddly enough "soluble in pure or acidified water, though, curiously enough, either silver nitrate or alkaline chloride will reprecipitate it from this solution. (This explains the so called 'neutral point' in the Gay Lussac method of estimating silver volumetrically)" -[The Metallurgy of Silver - Collins] 

It may be important to know (for some), that "If the gold is precipitated out via SO2 when this silver is in solution, it will form silver sulfite (AgSO3) [Loewen, pg 124]

Okay, Im done quoting books now, I just thought those two excerpts fit well in this thread... Back to your regularly scheduled programming


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## ARMCO

Topher_osAUrus said:


> Ive boiled AR and didnt suffer great losses as well.(when I had to, dissolving platinum)
> I simply use a watch glass, and a piece of fiberglass insulation balled up to put in the lip of the beaker, which soaks up any of the values that try to eek their way out of the vessel.
> 
> Not having the reaction vessel more than 1/3 full helps a great deal as well.
> 
> I dont usually heat it that strongly, but I always use the fiberglass plug, as even the bubbling from a regular dissolution of gold likes to find its way out of the beaker lip just as much.
> 
> ------
> 
> And, it may or may not be "technically" a precipitation, but the AgCl when in the gold chloride solution is held in as AgCl2, when diluted it becomes turbid and slowly falls to the bottom of the beaker.
> This "flaky condition" AgCl is oddly enough "soluble in pure or acidified water, though, curiously enough, either silver nitrate or alkaline chloride will reprecipitate it from this solution. (This explains the so called 'neutral point' in the Gay Lussac method of estimating silver volumetrically)" -[The Metallurgy of Silver - Collins]
> 
> It may be important to know (for some), that "If the gold is precipitated out via SO2 when this silver is in solution, it will form silver sulfite (AgSO3) [Loewen, pg 124]
> 
> Okay, Im done quoting books now, I just thought those two excerpts fit well in this thread... Back to your regularly scheduled programming


 

Actually, i really appreciate it. After a couple years of trial and error, YouTube, and some books I figured I should get involved in a forum. There is so much I don't know. I spend an inordinate amount of time, and have had success, but I'm still fighting certain problems. So, thanks again.


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## anachronism

ARMCO said:


> Are you speaking theoretically or from actual experience? I ask this respectfully. I HAVE had the experience of significant losses and have also been told by others that can happen, actually told WILL happen if you boil AR and I have never done it again. Everything I've looked up also strongly discourages boiling in favor of evaporation due to this occurrence as well.



It's from experience not just from theory. 8)


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## ARMCO

anachronism said:


> ARMCO said:
> 
> 
> 
> Are you speaking theoretically or from actual experience? I ask this respectfully. I HAVE had the experience of significant losses and have also been told by others that can happen, actually told WILL happen if you boil AR and I have never done it again. Everything I've looked up also strongly discourages boiling in favor of evaporation due to this occurrence as well.
> 
> 
> 
> 
> It's from experience not just from theory. 8)
Click to expand...


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## Noe1255

Excuse me i extract silver from silver contacts and my powder come out grey and a little bit green can i clean it with aqua regia to get rid of the green color


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## butcher

Don't do anything until you understand the processes, the problems you will likely encounter, and you understand the dangers and how to protect yourself and others from the risks to health and safety, and you understand how to treat and dispose of the toxic hazardous waste.

The silver alloys will not dissolve in aqua regia.

Nitric will dissolve the silver and the base metals, gold if any will not dissolve, depending on percentages PGM to silver some can follow silver into solution or remain insoluble with any gold, you can recover silver from the solution using copper metal which the silver can be washed and melted, or you could recover silver from solution by precipitating the silver out as silver chloride which would need other processes to convert the silver salt to the metal before melting...


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