# Silver chloride



## Walcam (Jul 31, 2019)

Hi i was watching some youtube vids on silverrecovery and got a bit puzzeled by silver chloride.

Most videos ive seen, people recover silver from silver chloride with lye and sugar, but why would the do that?
would it not be better to just add a more reactive metal like copper to the HCl solution?

i did some digging around for answers, and for Silvernitrate people use copper it seems, but why not for silverchloride?


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## archeonist (Jul 31, 2019)

Because silver in HCl is not in an ionic state, there is no free silver cause it is bound to chlorine. In HNO3 silver is present as free ions and can be replaced by copper to form copper ions and silver atoms


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## Walcam (Jul 31, 2019)

i see.. i learnt something new then..

but copper can be extracted with iron , so why is silver different in this regard?

does this also meen that gold also cant be precipitated with copper from AP?

worried that i have discarded waste containing precious metals.


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## kernels (Jul 31, 2019)

Very simply, Silver Chloride is a powder that is in the liquid, like sand in water. Silver Nitrate is in solution in the liquid, like salt in water.


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## peter i (Jul 31, 2019)

There is more than one way to skin a cat.
:mrgreen: 
And not all things theoretically possible work well in practical use.

When I have a really dirty alloy, I will dissolve it in nitric (gold will be left behind), and then precipitate with hydrochloric acid.
All chlorides, except lead, mercury and silver, are soluble, and leave with the wash water.
Careful washing with hot water removes anything soluble, lead chloride too, and I will not touch anything with mercury in it.

Then I acidify with hydrochloric, stick a piece of zink in it, and the silver chloride is reduced to silver as the zink dissolves.

Then a wash with hydrochloric to remove remaining zink, wash with water, drying and melting.

If done properly, it yields a pretty pure silver.


Silver sulfate and silver chloride acidified with hydrochloric- or sulfuric acid are easily reduced with zinc.
(But if you let the silver chloride dry, you will have hard lumps that are a PITA to reduce)

I have tried sticking a piece of copper in the silver chloride, and it is very slow and inefficient.
When you precipitate a silver solution with copper, you only want to reduce the silver (and anything nobler than silver, which is also valuable).
Dissolved silver irons are quite aggressive, thats why it works in solution.

In a solid state reaction you need a bigger hammer, in other words something further apart in the reactivity series (metallernes spændingsrække in our native tongue)
Zinc is cheap, has a nice reactivity and zinc compounds are soluble in acid. But you have to wash out anything nobler than zinc that you don’t want first (copper, iron), or it will be reduced too.

Other people use sugar/lye.
It has the benefit, that any sugar or sodium left behind will not contaminate the silver.
I’ve never done it.

Tradition and what you learned first weigh heavy!


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## modtheworld44 (Jul 31, 2019)

Walcam

It takes alot of energy at once to create the heat required,to break a chloride bond.Take some salt and melt it.Then take some silver and melt it.then take both and mix it while still molten bet you,ll recognize the results.This will give you a visual of how much energy and heat it really takes to make silver chloride.Then use the same amount of energy and heat to reverse the process...etc.Like aluminium in hydrochloric acid ,which generates the required energy and heat to free the silver from the solid chloride (which gets redissolved back into the acid),leaving you (silver and acid). THanks in advance.



modtheworld44


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## rickzeien (Jul 31, 2019)

peter i said:


> There is more than one way to skin a cat.
> :mrgreen:
> And not all things theoretically possible work well in practical use.
> 
> ...


How would you recovery any Palladium from the nitric solution? 

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## 4metals (Jul 31, 2019)

The problem with silver chloride is that if it isn't reduced to a metal before you try to melt it, you get a God-awful smoky mess. And often, values left behind in the slag. In my mind, the physical form of the chlorides is crucial in deciding how to process it. 

If it is nice, wet and fluffy, minimal lumps, and has been stored in the dark, then the caustic and corn syrup works well. Just make sure it mixes well and you're golden.....or at least silver! 

But if it has dried or was melted (as in skim off a miller chlorination) then I prefer to melt it. If you get too hot in the melting and there is any soda ash in there, you will get a smoky mess, but if you control the heat and stay around 900ºF it will melt without any smoke and pour like a flux. I pour that into thin sheets and break it up with a mill and tumble it in dilute sulfuric acid with some iron balls and the silver reduces to metal on contact with the iron balls. Again, good mixing assures a complete reaction. Any extra iron can be removed with a magnet and the silver is high purity. 

Once again demonstrating in refining there is always more than one way to skin a cat.


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## Shark (Jul 31, 2019)

Thanks 4metals, it is good to see you back on the forum!


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## peter i (Jul 31, 2019)

> How would you recovery any Palladium from the nitric solution?



Good question.
I have never worked with Pd.


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## rickzeien (Jul 31, 2019)

peter i said:


> > How would you recovery any Palladium from the nitric solution?
> 
> 
> 
> ...


Thanks for the reply. Maybe someone else ed here on the forum can answer it. 

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## snoman701 (Jul 31, 2019)

dont get pd in nitric to begin with! Or plan on distilling off all the nitrates. 


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## 4metals (Jul 31, 2019)

A solution of Dimethylglyoxime will selectively drop Palladium out of a silver nitrate solution. No need to get rid of the free nitric in solution.


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## rickzeien (Jul 31, 2019)

Thanks for the information. Is there a discussion or another place I can get educated on the process. 


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## Lino1406 (Jul 31, 2019)

Sorry to disagree. Here is what I got melting silver chloride with borax and soda ash (3 times AgCl weight). The observed holes are from O2, CO2 coming out


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## archeonist (Aug 1, 2019)

And also Cl2..

But did you get all of your silver? What was the weight of the silverchloride and what is the weight of your silver?


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## snoman701 (Aug 1, 2019)

I don’t think anybody disagrees that soda ash reduces silver, but it’s very easy to lose a good portion of your silver in the process. 

Rick...hoke has good instructions for using dmg. But while dmg will precipitate pd from nitric, it’s not inexpensive. 




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## snoman701 (Aug 1, 2019)

4metals said:


> The problem with silver chloride is that if it isn't reduced to a metal before you try to melt it, you get a God-awful smoky mess. And often, values left behind in the slag. In my mind, the physical form of the chlorides is crucial in deciding how to process it.
> 
> If it is nice, wet and fluffy, minimal lumps, and has been stored in the dark, then the caustic and corn syrup works well. Just make sure it mixes well and you're golden.....or at least silver!
> 
> ...



Interesting...so once you melt it, it’s brittle enough to mill well and get good contact? 


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## 4metals (Aug 1, 2019)

> Sorry to disagree.



That's not disagreeing, that's just another way to skin a cat.

I am sure you blended your charge well so the flux and silver chloride were well mixed. A step many forget. They pile all the chlorides in the crucible and the flux on top and wonder why their results are not what is expected.


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## 4metals (Aug 1, 2019)

> hoke has good instructions for using dmg. But while dmg will precipitate pd from nitric, it’s not inexpensive.



It is all a question of scale. If the Pd is in low concentration the effort to collect it can be a labor intensive task if it requires killing off the nitric. so DMG is an effective option.

If the Pd in solution is concentrated then you can kill the nitric with sulfamic acid (which may be more difficult than it sounds if it was a nitric dissolve) and then add ammonium chloride and sodium chlorate. 

Or you can react the free nitric with copper and cement the values and work with a smaller quantity of acid if you want to purify it further.


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## rickzeien (Aug 1, 2019)

snoman701 said:


> I don’t think anybody disagrees that soda ash reduces silver, but it’s very easy to lose a good portion of your silver in the process.
> 
> Rick...hoke has good instructions for using dmg. But while dmg will precipitate pd from nitric, it’s not inexpensive.
> 
> ...


Thanks. I have read it over a couple of times. I think I will read it again before I do a trial. 

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## rickzeien (Aug 1, 2019)

4metals said:


> > hoke has good instructions for using dmg. But while dmg will precipitate pd from nitric, it’s not inexpensive.
> 
> 
> 
> ...


Thanks. Before scale comes acquiring knowledge a skills. It comes at a cost that is not profitable but once acquired profits may come. 

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## snoman701 (Aug 1, 2019)

4metals said:


> > hoke has good instructions for using dmg. But while dmg will precipitate pd from nitric, it’s not inexpensive.
> 
> 
> 
> It is all a question of scale. If the Pd is in low concentration the effort to collect it can be a labor intensive task if it requires killing off the nitric. so DMG is an effective option.



Absolutely! Not to mention that there's a really good chance that if you are recovering from a solution with excess nitrate, you may not have paid on that Pd in the first place.


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## 4metals (Aug 1, 2019)

> Absolutely! Not to mention that there's a really good chance that if you are recovering from a solution with excess nitrate, you may not have paid on that Pd in the first place.



You would be amazed to know how much refiners profit from their mistakes!


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## BSGMiner (Aug 12, 2019)

First post--have mercy. :wink: I've spent hours reading a lot of posts so far, but I'd like to share my predicament and see if anyone could provide some clarification, please.

Back-story:
After reverse electroplating handfuls of silverware in a 1L mason jar of non-iodized saltwater solution, which most certainly now contains some of the copper, zinc, tin, etc. base metals, I then added--here's the kicker--30mL of Muriatic Acid (31% HCl) to dissolve the base metals. It was at this point that I realized too late that I might have just converted some of the Silver Oxide to Silver Chloride (even though it looks more like grey silt than the fluffy, white precipitate that I see and hear described).

Solution(?):
So, for a few reasons, any Lye-Sugar and/or Nitric Acid approaches are out of the question, but I do have Muriatic Acid--obviously--and I can get Battery Acid. I've seen it mentioned on here about the Sulfuric Acid-Iron and HCl-Aluminum methods, which both seem promising; however, I'm wondering if I have to use Iron or Aluminum versus the base metals that are already in the jar... Or, did the base metals protect the silver from becoming a chloride in the first place???


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## Shark (Aug 12, 2019)

BSGMiner said:


> First post--have mercy. :wink: I've spent hours reading a lot of posts so far, but I'd like to share my predicament and see if anyone could provide some clarification, please.
> 
> Back-story:
> After reverse electroplating handfuls of silverware in a 1L mason jar of non-iodized saltwater solution, which most certainly now contains some of the copper, zinc, tin, etc. base metals, I then added--here's the kicker--30mL of Muriatic Acid (31% HCl) to dissolve the base metals. It was at this point that I realized too late that I might have just converted some of the Silver Oxide to Silver Chloride (even though it looks more like grey silt than the fluffy, white precipitate that I see and hear described).
> ...





I am not sure this will answer all your questions but this is a good place to start.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=16591&hilit=water+stripping+silver#p167641


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## BSGMiner (Aug 12, 2019)

Shark said:


> I am not sure this will answer all your questions but this is a good place to start.
> 
> http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=16591&hilit=water+stripping+silver#p167641


Shark, His process is similar to what I do; however, I add salt to distilled water and use a stainless steel cathode.

Anyway, I'm wondering if what Marcel mentioned about a resulting dilute Copper Chloride is the key to the equation. Maybe CuCl has been the reason that the silver seems to get pushed off the silverware in the first place. I'll attach a pic of my current jar with familiar CuCl hues to them to see what everyone thinks.






If that's the case, though, I'm wondering if it's even possible to accidentally end up with Silver Chloride since there's already higher reactivity material in chloride form from the beginning if the experiment.

Am I thinking right about that, or am I falling victim to bias confirmation / wishful thinking?


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## Shark (Aug 13, 2019)

I really have no idea how copper chloride would effect it. The little I have done with this kind of cell I didn't seem to have much problems with. My first try was with city water that always has a faint smell of chlorine and some times it is so bad I couldn't drink the water. The connection was strong enough that I didn't add anything to the water. I used a large silver plated spoon and a smaller piece of flatware to strip from. I simply ran the slime's through sulfuric and iron, and melted the dirty results. I was more interested in the cell than the results so I didn't even try to calculate what I should have recovered.

The second try the local water was such that I could never get a decent connection so I add some salt, sodium chloride, for what ever reason the results were more dirty than my first run. The only thing changed was the salt addition and the water. There was way more contaminants with the second round. I have never had any color change to mine, most times I could just let it sit and it cleared up to look almost like water again. Yours certainly looks like it has some copper in it. Did it seem to strip faster or slower after the color change? 

I have been wanting to try it again, as I have about 100 pieces of silver plate flatware sitting in the way, and a stack of trays that needs to be gone as well. I just need time get caught up with what seems like a hundred other projects as well.


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## BSGMiner (Aug 13, 2019)

Shark said:


> ...I have never had any color change to mine, most times I could just let it sit and it cleared up to look almost like water again. Yours certainly looks like it has some copper in it. Did it seem to strip faster or slower after the color change?


I can't say that I noticed a difference in the speed between different (fresh) batches that I've processed--keeping in mind that I've used a few different power supplies (e.g. 45W solar panels, 12V deep cycle battery).

Actually, I believe it was the addition of HCl that caused the color change--it was really cloudy and saturated at the time. Also, I didn't add it until after I was done with that batch. To support that theory, my current cell is nearly clear as you mentioned whereas the jar that I keep accumulating it in, which contains the dilute HCl, is greenish as you saw in the last pic.

Below is the batch that I'm currently processing, which is just salty distilled water and silverware remnants.


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## Shark (Aug 13, 2019)

I missed that you added hydrochloric to it. That would explain the green color. I noticed that when I melted mine the crucible showed signs associated with copper. While I just melted mine after the sulfuric/iron treatment, I then ran it to a silver cell with very little problems. This may sound odd but my main interest in silver is in working with the silver cell, and this was a way to use silver I already had on hand that would also purify it. I am quickly building up a new batch of silver chloride, so I may set my cell back up and see how much I can add to it.


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## BSGMiner (Aug 13, 2019)

Very cool. Thanks for the input. I suppose you answered my next question of how you separated the silver and copper... Electrolysis. 

I'll finish reading the rest of that saltwater cell post you mentioned about since around page 2-3 it starts to get pretty interesting. Hopefully I can find out some more details along the way.

Best of luck!


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## BSGMiner (Sep 10, 2019)

peter i said:


> ...Then I acidify with hydrochloric, stick a piece of zink in it, and the silver chloride is reduced to silver as the zink dissolves.
> 
> Then a wash with hydrochloric to remove remaining zink, wash with water, drying and melting...


I'm just wondering how the reintroduction of HCl doesnt reconvert the silver back to silver chloride.

I can understand washing with H2O afterward, but I'm kind of puzzled about re-adding HCl...


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## nickvc (Sep 10, 2019)

Silver doesn’t dissolve in Hcl it does in nitric so washing with Hcl removes base metals, add some nitric plus Hcl you are back to silver chloride, does that make sense.


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## BSGMiner (Sep 10, 2019)

nickvc said:


> Silver doesn’t dissolve in Hcl it does in nitric so washing with Hcl removes base metals, add some nitric plus Hcl you are back to silver chloride, does that make sense.


2 things:
. I said convert back to silver chloride not "dissolve"
. I think because mine was silver oxide (Ag2O), adding HCl created AgCl + H2O

EDIT: I think I get what you were trying to say now, but the odd punctuation threw me off the first time I read it.


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## BSGMiner (Sep 11, 2019)

Just to be sure, I dissolved a drop of my gray precipitate with ammonia last night, so I definitely have silver chloride without ever having added nitric acid.

EDIT: Removed a part at the end that confused things.


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## anachronism (Sep 11, 2019)

What colour did your ammonia turn and how quickly and how deep?

Edit: The exception doesn't prove the rule. Yes it's possible that with some external factors you don't strictly require other "approved" things for HCl to dissolve silver. In the real world of refining, outside the stoichiometric world of theory, there will be a small amount of Silver going up in your HCl. Why? Because there are often things in your "mix" that allow this to do so. As soon as you have an impure situation, the rule book has to be interpreted rather than taken as gospel. 

The greater the grasp of chemistry, the more these impure situations can be evaluated and understood so that at first glance you have a darned good idea of what's really happening. 

This has been an ongoing point of discussion (and sometimes a bone of contention) between those who theorise about refining and those who actively do it for at least as long as I have been on GRF however regardless of which side of the fence people sit on there is a concensus that real/theoretical are completely different cases. 8) 8) 

So yes you're going to have an amount there in all likelihood however it's also likely to be a small amount. 

Jon


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## anachronism (Sep 11, 2019)

Oh another thing. Do bear in mind that just because Ammonia dissolved grey deposit, you have to remember that Ammonia will dissolve a whole heap of things not just Silver.


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## BSGMiner (Sep 11, 2019)

Thanks for all the input, and to answer your questions:

Yes, it's definitely an impure solution resulting from reverse electroplating silver plated flatware. After a strong copper chloride solution had been used and decanted, I took one drop the gray precipitate, which required a few milliliters of ammonia to dissolve.

It resulted in a light blueish liquid (probably from some remaining copper chloride that hadn't been washed out yet), and since I was using a pipette to drip the ammonia onto the precipitate, it took roughly a minute to dissolve the entire drop of gray precipitate.


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## anachronism (Sep 12, 2019)

BSGMiner said:


> It resulted in a light blueish liquid (probably from some remaining copper chloride that hadn't been washed out yet), and since I was using a pipette to drip the ammonia onto the precipitate, it took roughly a minute to dissolve the entire drop of gray precipitate.



I would recommend that you do some searching on the effect of Ammonia upon Silver Chloride and the resulting colour. 8) 

Jon


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## modtheworld44 (Sep 12, 2019)

BSGMiner said:


> Very cool. Thanks for the input. I suppose you answered my next question of how you separated the silver and copper... Electrolysis.
> 
> I'll finish reading the rest of that saltwater cell post you mentioned about since around page 2-3 it starts to get pretty interesting. Hopefully I can find out some more details along the way.
> 
> Best of luck!



BSGMiner

THIS cell is not a saltwater cell,and that is why you are having so many mixed results.Stop using salt water and use water straight from your tap.



modtheworld44


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## BSGMiner (Sep 12, 2019)

modtheworld44 said:


> Stop using salt water and use water straight from your tap.


How can you be sure there are no chlorides present in your tap water?


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## anachronism (Sep 12, 2019)

modtheworld44 said:


> THIS cell is not a saltwater cell,and that is why you are having so many mixed results.Stop using salt water and use water straight from your tap.
> 
> 
> 
> modtheworld44



That doesn't change the chemistry Jerry.


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## snoman701 (Sep 12, 2019)

I don’t know what’s really going on in this thread...but we know not to let ammoniacal silver evaporate right? Add acid please.


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## BSGMiner (Sep 12, 2019)

snoman701 said:


> I don’t know what’s really going on in this thread...but we know not to let ammoniacal silver evaporate right? Add acid please.


I should've clarified that it was immediately treated and disposed.


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## BSGMiner (Sep 18, 2019)

Wow, things are looking better after alternating three hot rinse and spin cycles of HCl and H2O! Each time the solution got less green, and now I can't tell a color difference between HCl and H2O.


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## BSGMiner (Sep 19, 2019)

Also, I weighed the silver chloride in between washes, and it's ~90g (~2.9ozt), which according to molecular weigh (75% Ag / 25% Cl) should be at least 2ozt by the time it's reduced to metallic silver. 8)


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