# separating silver and palladium



## Geo (Dec 9, 2016)

Okay, I have a question that someone may be able to help me out with an answer. This is from wiki :
https://en.wikipedia.org/wiki/Palladium
"Elemental palladium reacts with chlorine to give palladium(II) chloride; it dissolves in nitric acid and precipitates palladium(II) acetate on addition of acetic acid."

Further reading :
http://en.wikipedia.org/wiki/Palladium(II)_acetate
"When warmed with alcohols, or on prolonged boiling with other solvents, palladium(II) acetate decomposes to palladium." It decomposes at 401°F. 

Also, a search for silver acetate on wiki : https://en.wikipedia.org/wiki/Silver_acetate doesn't state anywhere that adding the acetic acid to silver nitrate will precipitate silver acetate. This seems to me to be a way to precipitate Pd out of solution and leaving the silver nitrate to be cemented on copper. 

Any thoughts?


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## g_axelsson (Dec 10, 2016)

You need a lot of water for it to work. Silver acetate has a solubility of 10g per liter, anything more than that and it will precipitate too. Near boiling temperatures might help but how much I don't know.

I think that chloride ions is the best way to separate silver and palladium.

Göran


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## justinhcase (Dec 10, 2016)

As I only get a very small amount of Pd in,Mostly ring settings and some old dental crown's.
It shows up in my silver cell.
I crystallize my electrolyte to recover most of the AgNO3 ,it some times takes two or three runs but I eventually get a pure white crystal,and a concentrated solution of all the impurity's from the cell.
I have been using D.M.G. to precipitate the Pd before cementing the residual Ag.
It is a bit voluminous but in three years I have only half filled a 500ml jar.
Where as I have half filled a 60L drum with my chloride bin as it is and am loath to make any more AgCl.
I would like to process it but I still have not had the time to build a drum rotator. 
At lower concentrations of Pd I find the benefit of producing elemental silver out weigh the inconvenience of D.M.G. as a precipitant.
Though if you where dealing with stock of a higher level Pd I could see a Chloride based approach making life a lot easier.


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## nickvc (Dec 10, 2016)

Geoff with a silver palladium nitrate solution I would be tempted to create silver chloride using salt, decant and then filter the silver chloride again with plenty of rinses and then cement the palladium, I like simple easy to follow processes which are pretty fail safe , failing that use weak AR and create silver chloride and use the same recovery methods.
For any members who have an Au, Ag, Pd solution be aware that when you precipitate the gold many precipitants will also co precipitate some Pd so use nitric rinses after good water rinses if you want good clean gold.


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## anachronism (Dec 10, 2016)

Geoff I would go with Nick's idea.

Drop the silver chloride out of the solution filter till pure and precipitate out the Pd as metal.


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## Lou (Dec 10, 2016)

If it's silver free (or more safely, with a very very low amount of silver, but some still in there as AgNO3) and you can find it in yourself not to use an excess of chloride in any circumstance you could...

precipitate the palladium (and trace silver) with sodium bromide. Filter it and dissolve up the palladium in sulfite and go from there, or just add HCl and an oxidant (not too much, you don't want to dissolve the silver chloride in excess HCl), heat, filter, and then go about it the usual way.


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## kurtak (Dec 10, 2016)

Geo said:


> Further reading :
> http://en.wikipedia.org/wiki/Palladium(II)_acetate
> "When warmed with alcohols, or on prolonged boiling with other solvents, palladium(II) acetate decomposes to palladium." It decomposes at 401°F.



One more thing to make note of here being as how you are talking about palladium AND silver in solution together (which would be a nitrate solution)

Per the underlined above - DO NOT add alcohols "of any kind" to a silver bearing solution - that's is how fulminates are formed (precipitated) such as mercury &/or silver fulminate

Fulminates are "very" pressure sensitive explosives & silver fulminate is "much more" pressure sensitive then mercury fulminate - in fact it is so pressure sensitive that it will detonate under its own weight (while precipitating) AND while wet

Silver fulminate is used to make the little "novelty" fire works "snaps" - the little balls you throw on the ground & they snap (or you can pinch them & they snap) --- ok - so now your may think - well if they use silver fulminate to make those snaps it can't be all that dangerous --- well the reason those snaps are not a "high" danger - is that there is only about 80 "micrograms" of silver fulminate in the snap - in other words those snaps only have about 80 "millionths" of a gram of silver fulminate in them - which means a gram of silver fulminate would be 12,500 times more explosive then one of those snaps

Kurt


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## Geo (Dec 10, 2016)

My interest is due to the problems of wet processing SMD's. There will be more silver by volume than Pd. If silver acetate will precipitate, that's the end of it. I have been trying to figure out a more simple path to selectively precipitate the Pd first leaving the silver nitrate intact. Since Dudadiesel is just a couple of miles from my home and they sell glacial acetic acid fairly cheap and I could get it to work, I would be in a good position to process SMD's for toll refines. DMG is too expensive for large processing needs.


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## jeneje (Dec 10, 2016)

Geo said:


> I have been trying to figure out a more simple path to selectively precipitate the Pd first leaving the silver nitrate intact.


Geo, not sure here, but want Ammonium Chloride drop the Pd leaving the Ag as AgCl in solution? It may however, create an explosive mixture not sure. Just a though.

edited: just as an after though, it may precipitate out the Ag as AgCl leaving the Pd.

Ken


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## justinhcase (Dec 10, 2016)

jeneje said:


> Geo said:
> 
> 
> > I have been trying to figure out a more simple path to selectively precipitate the Pd first leaving the silver nitrate intact.
> ...


How do you separate the AgCl and the Palladium(II)-ammonium chloride.most of the AgCl drops out at the same time.
you need to use sodium chloride first for the Ag then the Ammonium Chloride for the Pt.
Crystallization would reduce the amount of silver involved in any case.
Unfortunately I have not seen any other options or it would be in regular use,it would be handy..


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## Geo (Dec 10, 2016)

jeneje said:


> Geo said:
> 
> 
> > I have been trying to figure out a more simple path to selectively precipitate the Pd first leaving the silver nitrate intact.
> ...


Yea, it would precipitate silver chloride. If the palladium(II) acetate can be converted to metal directly by heating in organic solvent, that would actually eliminate a couple of extra steps. Organic solvent can be any organic aromatic, even gasoline. I will have to try a couple of small experiments at a safe distance to see how everything will react. If silver acetate precipitates, it will end the experiment. Excluding the explosiveness of any byproduct, it will be much safer than dealing with trying to convert Pd salts using other methods.


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## jeneje (Dec 10, 2016)

justinhcase said:


> jeneje said:
> 
> 
> > Geo said:
> ...


All I done was made a suggestion, one of the Chemist's would have to answer your question Justin. Sorry.

Ken


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## jeneje (Dec 10, 2016)

Geo, i would think any by product could be reacidfied with HCl, I would not use HNO3 as you know might cause a small issue if ammonina is present. :lol: BOOM! Interesting to say the least.

Ken


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## Geo (Dec 10, 2016)

It shouldn't be basic at any time. Acetic acid (vinegar, or in this case, concentrated vinegar) is acidic. It is a weak acid with a PH of less than 5. It is an organic compound.


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## anachronism (Dec 10, 2016)

Geo said:


> My interest is due to the problems of wet processing SMD's. There will be more silver by volume than Pd. If silver acetate will precipitate, that's the end of it. I have been trying to figure out a more simple path to selectively precipitate the Pd first leaving the silver nitrate intact. Since Dudadiesel is just a couple of miles from my home and they sell glacial acetic acid fairly cheap and I could get it to work, I would be in a good position to process SMD's for toll refines. DMG is too expensive for large processing needs.



Geoff it's a two way street and you've got the theory nailed you just need to pick one of the two main methods. i.e. Get rid of the silver and keep the Pd in solution or vice versa. Either works, it just comes down to which you feel more comfortable with. Personally I would rather precipitate out the Pd in metal form second and store the impure metal until I have enough to assay and sell as a batch of Pd metal. I don't like messing with Pd salts for reasons already known. Whether the Pd is pure or not doesn't matter as you still get paid on the Pd content on a good lump.

You could even process that all as one Pd batch if you're comfortable doing so however doing it in multiple batches is more likely to cause health problems. That's just my 5 cents take it or not as you choose mate, I won't be hurt.  

Jon


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## Geo (Dec 10, 2016)

Jon, I'll have to break it down a little further to get to what I am after. Cementing the silver as metal is easier than converting silver chloride. Palladium(II) acetate is listed as non-hazardous. To me, converting palladium nitrate to a non-hazardous compound in one go is just as good as converting to metal in one go as far as safety is a concerned. Converting the silver to silver chloride will actually be just adding more steps. The palladium(II) acetate is converted in what I would call a wash somewhat like washing dropped powder. If it works, it will cut down on a lot of steps.


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## anachronism (Dec 10, 2016)

Yeah. I hear ya loud and clear. Less steps overall is a win. Personally I detest converting silver chloride to metal but prefer the sulphuric/iron approach if I have to do it.


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## Lou (Dec 11, 2016)

Geo said:


> jeneje said:
> 
> 
> > Geo said:
> ...



Ok. Maybe third time post in this topic is the charm. First one got goofed up by the forum software. Second one I decided to delete. 

I'm trying to say this nicely Geo. Tonight was the night that I really truly wanted to quit posting here, and this post you made was why. I'm sorry I didn't communicate better up thread. I'll go fix it. That's on me. It's also on me (and the other mods) for letting this conversation get far enough to have you making such bold claims as you made above. I know you don't care for me or what I have to say, but I don't care for what you had to say above--not one bit-- and I can promise you that this is your first and last warning so long as I have anything to do with this forum. DO NOT CLAIM THAT SOME METHOD IS SAFE or that it WILL BE. 

The idea of precipitating palladium acetate from a silver/palladium nitrate solution isn't a grand one. It just isn't going to work acceptably. Or cheaply. 

Most importantly: GASOLINE IS NOT THE ANSWER and is taking an unnecessary risk. Heating palladium acetate by itself will decompose it (to black hard to filter tar unless it's really cooked long past the vinegar smell). Doing so will also decompose silver acetate at the same time too-- they decompose completely at about the same temperature. 

Anyway, if a sane person wants to separate the two, there are many methods for doing so if that person's willing to take the time to find out how much Ag and Pd he has in the first place!!

The easiest way is separating the silver chloride out, washing it well in the filter with dilute acid to remove the palladium salt still absorbed (the filtrate coming out is colorless, that means no more Pd stuck in the silver). At that point the silver chloride is easily converted to metallic silver by stirring/tumbling with iron pieces and dilute sulfuric acid (like 5-10 percent, little less than what's in a car battery). That makes silver metal powder. That silver powder needs filtered, iron removed with a magnet wrapped in saran wrap, and rinsed free of iron sulfate with hot water. Then it should get washed with borax and soda ash solution and melted. Works 100 percent of the time and with virtually 100 percent yield.

The left over de-silvered palladium nitrate solution might have some excess HCl. If it's just palladium in the solution and not much in the way of base metals, then one can precipitate the Pd as its hydroxide at a pH of 7.5. Best to add base to pH 1 in big dollops to get the heat of neutralization. Then slowly add base until the appropriate pH is reached, while boiling. That gives hydrated palladium oxide/hydroxide. 

Another nice option that doesn't involve killing yourself with heating gasoline is to use the formate method that 4metals discusses. Guess what comes out with formate before the silver? That's right. Palladium. Might have a wee bit of silver contamination, especially if the relative amounts of each aren't known.

Another option is to adjust the pH up somewhat again (this time to pH=1) and use copper to cement the palladium out selectively.

The fourth option I'll put up above in my very poorly explained post above.


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## Platdigger (Dec 11, 2016)

Lou, as many if not all are well aware, this forum would suffer greatly if ever you were to quit posting here.
I sincerely hope we have not offended you somehow.
I actually think the main reason this thread went as far as it did, was no one else really knew for sure if the acetate method would work acceptably or not. Other than yourself I mean.


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## Geo (Dec 11, 2016)

Wow Lou, that really hurt. What makes you think I don't care about your opinion? If I didn't care, I would have went ahead and tried it first and then come asking for advice on how to clean it up. What little I know about refining, I learned it here. Any sane person would know that this is the place to learn about refining. I didn't mean to state that heating flammable liquids is safe. In fact, I would never recommend anyone actually do it. All of this is hypothetical. I was stating an opinion on the safety part and not trying to state fact. I will drop this subject as soon as I make this post. Since I have all the chemicals and materials, I will go ahead and experiment as best I can and see what kind of mess I make. If it turns out totally fubar, I can chunk it all in the dump and that will be that. At least if I blow myself up, it will make for a great youtube video.


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## nickvc (Dec 11, 2016)

Geoff converting silver chloride back to metallic silver is a pain in large quantities but simple in small ones and if you have a cement mixer with a plastic barrel even large quantities are fairly easy.
Call me chicken but I'd still go down the creating silver chloride and cementation of the palladium route, it's well documented and known to work and reasonably safe, allowing for the fact you have PGM salts in the mix.


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## jeneje (Dec 11, 2016)

Geo said:


> Any sane person would know that this is the place to learn about refining.


Hey, I resemble that remark. :lol: There are one or two other places also!  Just a note here of course and i consider myself sane. However, I will check with my counselor at our next visit. :lol: 

Ken


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## Platdigger (Dec 11, 2016)

"Another option is to adjust the pH up somewhat again (this time to pH=1) and use copper to cement the palladium out selectively."
Just trying to understand this one Lou. Hope you are not too opposed to posting to this thread again.
If not, could you elaborate? What keeps the silver from also cementing? Is it a timing thing?


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## g_axelsson (Dec 11, 2016)

Platdigger said:


> "Another option is to adjust the pH up somewhat again (this time to pH=1) and use copper to cement the palladium out selectively."
> Just trying to understand this one Lou. Hope you are not too opposed to posting to this thread again.
> If not, could you elaborate? What keeps the silver from also cementing? Is it a timing thing?


My guess is that it applies to the silver free liquid after the silver chloride have precipitated. It's an alternative to precipitate palladium as hydroxide or reduced by formate.

Göran


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## Lou (Dec 11, 2016)

Geo said:


> Wow Lou, that really hurt. What makes you think I don't care about your opinion? If I didn't care, I would have went ahead and tried it first and then come asking for advice on how to clean it up. What little I know about refining, I learned it here. Any sane person would know that this is the place to learn about refining. I didn't mean to state that heating flammable liquids is safe. In fact, I would never recommend anyone actually do it. All of this is hypothetical. I was stating an opinion on the safety part and not trying to state fact. I will drop this subject as soon as I make this post. Since I have all the chemicals and materials, I will go ahead and experiment as best I can and see what kind of mess I make. If it turns out totally fubar, I can chunk it all in the dump and that will be that. At least if I blow myself up, it will make for a great youtube video.




Thank you Geoff. 

Maybe I am over reacting after a long day of painting, then playing dad solo. And I'm sick to boot. So I may be having a Harold moment. I'm just frustrated because there are a lot of better ways. 

At the end of the day though, I just don't want to see anyone get hurt and I did not like claims about how something will be safer or better and yet potentially involve gasoline. I've worked with palladium and silver acetate and made them before for people to buy and use. 

I've done a lot of really stupid, and really dumb things myself and thank goodness I still have all of my toes and fingers and lungs left to show for it. I've been flat-out lucky. Once upon a time, I had myself a close call, and realized that luck is one of those things that runs out.

There's a quote by Abraham Lincoln that sums up how I feel about refining anymore. Something about 8 hours to cut down a tree but six hours were spent sharpening the axe. 


@Platdigger and Goran: 
Yes, it's done after the silver is precipitated to adjust the acidity. If iron is present, it shouldn't even go that high in pH lest ferric hydroxide is made. This is so a big bar of copper doesn't go into a bunch of concentrated nitric acid. If one adds HCl to precipitate the silver, the displacement reaction gives nitric acid again. If one adds sodium chloride to remove the silver, then sodium nitrate is left behind. 


Here are some references:
https://www.google.com/patents/US3318891

another good one:

https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US6290749.pdf


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## Topher_osAUrus (Dec 12, 2016)

Kids are invredible arent they?
They can test our patience to the breaking point, and then melt your heart the next minute... And they never seem to get tired when you want them to... When you yourself are exhausted from tending to them from when they first wake up... It's almost like they are little midget gasoline theives, stealing the life force from us.

Glad you are sticking around Lou, this place wouldn't be the same without you. 
...But i definitely feel your pain on the solo parent thing.. My wife works 3rd shift, so its me and the boys, all the time.

It gets better! (so I've been told) :mrgreen:

Edit to fix typo


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## FrugalRefiner (Dec 12, 2016)

Topher_osAUrus said:


> It gets better! (so I've been told) :mrgreen:


Who told you that? They lied! :lol: 

Dave


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## upcyclist (Dec 12, 2016)

This may not serve Geoff's purposes, but I'm surprised no one mentioned processing cemented silver in a cell*, where Pd (and other trace PGMs) would end up in the slimes.

That's probably not a great solution if you're toll refining, though, and your customer wants Ag AND Pd. But it would seem that many folks on here process _one _metal for the customer, and they keep the rest (e.g., "I'll process your karat scrap, give you the gold (minus toll), and I keep any silver and PGMs"). Toll refining multiple metals out of one feedstock means you're adding a premium, hopefully? Because single batches of trace elements has got to be a PITA. 

I guess I'm not clear on your motives--if you want to know what's in your feed stock so you can evaluate the ROI, then you can probably ignore everything I wrote 

*Note that I haven't even gotten to the cell part of that strategy above, but that is my intent, and for me it's all personally owned material by that point.


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## kurtak (Dec 13, 2016)

upcyclist said:


> This may not serve Geoff's purposes, but I'm surprised no one mentioned processing cemented silver in a cell*, where Pd (and other trace PGMs) would end up in the slimes.



Due to the fact that Pd is soluble in nitric only some of the Pd stays in the slimes - some of it dissolves into the electrolyte (corrupting the electrolyte) just as copper &/or any other nitric soluble metals - some (including silver) remain behind in the slimes - some goes into the electrolyte --- only metals that are not soluble in nitric remain in the slime without also going into the electrolyte

How the (silver) cell works --- you have to think in terms of a "winning" cell - because that is actually what is going on - the difference is that in the silver cell you are using an (impure) silver anode instead of an inert anode like carbon or platinum plated titanium - but - both the winning cell & the silver cell work on the same principal - which is the "displacement" of the metal dissolved in the electrolyte which causes it to deposit at the cathode as a result of the DC current applied to the cell (positive to the anode - negative to the cathode)

In the winning cell - because an inert anode is used - the metal in the electrolyte is displaced from the electrolyte & deposited to the cathode - the end result being that the metal is removed leaving you with acid that is now free of the metal that was dissolved in it - which in turn means you now have acid that is free to dissolve metal again

And that is what happens in a silver cell - because your electrolyte is made of "silver" in the "first place --- when you turn on the power - silver starts to be displaced "from the electrolyte" --- which in turn frees up acid that is then able to dissolve metal at the anode - that acid (being nitric) dissolves not only silver - but any metal that is nitric soluble such as copper, palladium, etc. 

The result is metal ions being replaced by the acid made free as silver is displaced - BUT - the replaced ions are made up of any metal that is nitric soluble --- therefore you electrolyte SLOWLY begins to "corrupt" --- because this reaction is taking place so slow AND as long as the silver ions are the "predominant" ions in the electrolyte - the silver ions are the ions that continue to displace "from the electrolyte" --- in other words - the silver continues the be the metal "won" from the electrolyte - as long as they (as ions) dominate the electrolyte

When the electrolyte becomes to corrupted with other metal ions (due to being "dissolved" from the anode) so that the silver is no longer dominating the electrolyte - they also start to displace (or win) from the electrolyte leading to co-depositing of those other metals to the cathode as well as the silver

Also because the reaction of displacement & replacement is taking place so slowly - the free acid that is made available to dissolve metal at the anode is so little - it is also to "weak" to "fully" react with the metal & "completely" dissolve it - so the result is "some" metal being dissolved (to replace ions in the electrolyte as ions are displaced) but some metal also flakes off as "ultra fine" metal resulting in the slimes

In other words - not only the metals that are "not" soluble remain in the slimes - but - "some" metal that "is" soluble in nitric also remains in the slimes - while some (nitric soluble) metal is dissolved allowing metal ion replacement of the electrolyte as metal ions are displaced from the electrolyte 

The sort version of the above long story is - the silver cell "does not" work by "transferring" silver from the anode to the cathode thereby leaving everything but the silver in the slimes - rather it wins (displaces) silver "from the electrolyte" which provides free acid to dissolve metal at the anode (any metal that nitric will dissolve) thereby replacing ions to the electrolyte as ions are won from the electrolyte

Sooo - the silver cell is not going to do what Geo wants to do - which is to completely "part" the Pd from the Ag --- the silver cell will give him pure silver "at the cathode" --- as long as he does not allow the electrolyte to become to corrupted that it starts co-depositing - BUT - he will still end up with the Pd mixed with silver - some that is a complex of Ag/Pd nitrate (in the corrupted electrolyte) & some as a matrix of Ag & Pd in the anode slimes --- meaning he is still stuck with "parting" the two metals from each other 

So - yes - though he can achieve pure silver by running it in the silver cell - he still has the problem of parting Pd from Ag in the by products of the cell - & the Pd/Ag are now in two places - some in the electrolyte & some in the slimes

Edit to add; - & that is why no one has suggested the silver cell as a solution to what Geo wants to do

Kurt


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## upcyclist (Dec 15, 2016)

Thanks for the explanation, Kurt!


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