# palladium from nitrate solution



## Sucho

Hi all !
is there any possibility to cement out palladium from a solution of various nitrates quickly and selectively?

//i will drop out Ag and Pb chlorides first using lab grade NaCl.

DMG is too expensive in a large shape and drop out Pd with Ni.
converting nitrates to chlorides is time-consuming and laborious.
cementing on copper- i think that is a good way to push out only Pd, but i have never tried this.
should i use copper cable /powder/sheet metal ? works this method well ?


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## Barren Realms 007

You would want to use bar stock, pipe or sheet's. Wire will possibly break apart as it dissolves and leave small pieces in the bottom of your container and powder you might put too much and have excess left in the bottom of your container. Reprocess your material when you have it concentrated and follow the forum recomendations.


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## Sucho

but there is a problem with adsorbing reduced palladium on a copper surface which causes "passivation" of copper

i have seen it before when i was cementing silver from silver nitrate solution with a small ammount of palladium nitrate.
i was thinking about using copper powder in a calculated ammount

is there any type of selective titration for palladium nitrate in a sol. of various nitrates or i have to use gravimetric determining with DMG and calculate ammount of Copper ?


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## lazersteve

If you have a relatively clean Pd nitrate ( ie: no other precious metals) solution you can use SMB to precipitate the Pd metal and refine it a second time for higher purity.

Steve


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## Sucho

thanks Steve!

that is very useful! i will try it. hope it will drop quantitatively.

there is mainly Cu in the solution after droping Ag,Pb with Nacl...
DMG is really too expensive for large shape Pd precip.from 50 grams of DMG you have cca 22 grams of Pd.


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## Sucho

Finally , i will do it with DMG in DMSO.

i have found a shop with great prices. DMG 50g - 1.9 Eur
 DMSO 1L - 18.2 Eur

Thanks for all replies


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## freechemist

You can forget about DMSO and spend your 18.2 Euro on different ways. DMG dissolves easily in aqueous NaOH. Use 2 moles of NaOH per mole of DMG and sufficient water to make up a solution of about 1 mole/lt NaOH. Adding this alkaline solution of DMG slowly to the nitrate solution will precipitate Pd selectively and quantitatively, without precipitation of Ni, provided the mixture will still remain acidic after addition of the alkaline precipitation agent. This can be assured by beforehand addition of an equimolar amount of nitric acid (2 moles per mole of DMG) to the nitrate
solution.


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## Palladium

Welcome to the forum.


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## Platdigger

Yes, Welcome!


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## Sucho

freechemist said:


> You can forget about DMSO and spend your 18.2 Euro on different ways. DMG dissolves easily in aqueous NaOH. Use 2 moles of NaOH per mole of DMG and sufficient water to make up a solution of about 1 mole/lt NaOH. Adding this alkaline solution of DMG slowly to the nitrate solution will precipitate Pd selectively and quantitatively, without precipitation of Ni, provided the mixture will still remain acidic after addition of the alkaline precipitation agent. This can be assured by beforehand addition of an equimolar amount of nitric acid (2 moles per mole of DMG) to the nitrate
> solution.



Thanks for a solution, equimolar calculations and welcome !
Great post !


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## shyknee

That's going to be my next experiment when things warm up.If it works cool just want to see how voluminous it is.


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## 4metals

> precipitate Pd selectively and quantitatively



This should also serve to determine Pd in parting solutions. For dental alloys that is a good time saver. Definitely will give this a shot. 

Thanks freechemist and welcome to the forum.


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## HAuCl4

freechemist said:


> You can forget about DMSO and spend your 18.2 Euro on different ways. DMG dissolves easily in aqueous NaOH. Use 2 moles of NaOH per mole of DMG and sufficient water to make up a solution of about 1 mole/lt NaOH. Adding this alkaline solution of DMG slowly to the nitrate solution will precipitate Pd selectively and quantitatively, without precipitation of Ni, provided the mixture will still remain acidic after addition of the alkaline precipitation agent. This can be assured by beforehand addition of an equimolar amount of nitric acid (2 moles per mole of DMG) to the nitrate
> solution.



Nice post!. Any suggestion to cleanly precipitate all Pt from Pt nitrate present after doing the Pd?. :?: 

Is there a simple procedure to manufacture DMG at home from cheap precursors?.

I also want to learn to make Oxalic acid at home from cheap precursors. :shock:


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## Sucho

DMG synthesis...// this is only my memories from organic chemistry, i dont study organic chemistry

but 2,3 diol ---oxidize ----> but 2,3 dion -----hydroxylamine---> DMG

but 2 en ---- KMnO4 dil. ----> but 2,3 diol

i dont remember temperatures and other parameters
i think synthesis of DMG at home is quite difficult.

Chemists, please correct my synthesis or suggest other procedure
Thanks


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## 4metals

> i think synthesis of DMG at home is quite difficult.



General rule of thumb. If you can't say it 3 times fast; forget about making it at home. :lol:


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## Lou

Forgettaboutit!

Really only useful if there's a bunch of stubborn PGMs that keep co-mingling. I prefer to use it to scavenge Pd rather than use it to remove Pd if it's the bulk constituent of the solution.

Lou


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## HAuCl4

For quick assay of 4metals :lol: (Ag, Au, Pd, Pt) in a mixed button, I think it is a great idea. :shock:

Weight button, dissolve in AR, filter AgCl, drop Au with oxalate, filter, drop Pd with DMG, filter, drop Pt with formate, filter. Weight them all. Perhaps not the best and most accurate, but accurate enough with normal buying margins, relatively simple and fast.

If DMG could be made or purchased cheaply, I can see how it could be used in refining too, because the Pd product is quite pure and more importantly it is almost completely removed from contaminating the Pt. A nuisance like silver chloride, but no more IMO.


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## HAuCl4

HAuCl4 said:


> Is there a simple procedure to manufacture DMG at home from cheap precursors?.
> 
> I also want to learn to make *Oxalic acid at home from cheap precursors*. :shock:



"... *of sodium formate which is dehydrated to solid formate, melted carefully at about260° C and then rapidly fused at 400° C for 5 to 10 minutes resulting in solid sodium oxalate and the evolution of hydrogen*."

http://www.patentstorm.us/patents/4018875/fulltext.html

Oxalate down. DMG to go next!. :shock: :lol: 8)


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## lazersteve

lazersteve said:


> If you have a relatively clean Pd nitrate ( ie: no other precious metals) solution you can use SMB to precipitate the Pd metal and refine it a second time for higher purity.
> 
> Steve



Correction. 

I tried this yesterday and had mixed results. The result was a bright yellow powder that tested positive as a Pd salt, not a fine black powder as expected (Pd metal). I read the source literature again and noticed it said SO2 gas, not SMB so I figured the sodium ions worked to form a double salt with Pd instead of the metal as expected.

I added my SMB dry, perhaps if I had dissolved it in a little HCl first I would have had better results. I also noticed I did not get any precipitate even after the SMB fully dissolved, until I added additional water.

More to come....

Steve


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## freechemist

Hello Steve,

Palladium(II) forms complex salts with sodium or potassium sulfite. The potassium salt has the composition K2Pd(SO3)2 and is commercially available from Alfa Aesar Company. With sodium sulfite Pd(II) forms a bright yellow complex salt with approaching composition corresponding to the formula Na2Pd(SO3)2x2H2O, containing about 31% Pd. As far as I know, this sodium salt is commercially available too, from Heräus Precious Metals Chemicals in Hanau (Germany). It is a bright yellow powder, only sparingly soluble in water. In excess aqueous ammonia it dissolves giving a colourless solution, probably containing the complex cation [(NH3)4Pd]2+ and sulfite as anion. Boiling the salt in excess aqueous sulfuric acid - no halides, nor nitrates may be present! - it decomposes to metallic palladium, NaHSO4, SO2 and water.

Regards, freechemist


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## lazersteve

Thanks freehemist, that explains my experimental observations.

Steve


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## kjavanb123

Please advise this method is correct or not.

Drop the Pd and other contaminants from the Pd nitrate using zinc, wash with boiling water, decant, then drop HCL to the residue, heat, that would dissolve any other contaminants except Pd, decant, wash, decant, and finally for more purifcation of Pd residue, dissolve it in ammonia, drop it HCL and get the yellow salt.

Thanks
Kev


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## lazersteve

kjavanb123 said:


> Please advise this method is correct or not.
> 
> Drop the Pd and other contaminants from the Pd nitrate using zinc, wash with boiling water, decant, then drop HCL to the residue, heat, that would dissolve any other contaminants except Pd, decant, wash, decant, and finally for more purifcation of Pd residue, dissolve it in ammonia, drop it HCL and get the yellow salt.
> Kev



No.

From my observations and Freechemist's reply above I would take the Pd nitrate solution and add SMB in water to give the bright yellow Na2Pd(SO3)2x2H2O, containing about 31% Pd. Test your left over solution with DMG for traces of Pd, if present add to your PGM stock pot.

Dissolve the bright yellow Pd salt in excess ammonium hydroxide, filter and precipitate the canary yellow Pd ammonium chloride with HCl. This is the purified Pd salt we have made in the past. It gets converted to Pd metal via incineration or zinc in 5% HCl.

Steve


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## kjavanb123

Steve,
This is what happened when i tried using SMB with Pd nitrate solution from 4 combs.
1. I dissolved 54g of SMB in 100ml of hot water, and there is the Pd nitrate solution from dissolving the black powder from 4 combs in nitric.


2. After addition of 2 more 100ml + 54g SMB solution to the Pd nitrate solution it changed to color below.


3. After 4th SMB solution addition the Pd nitrate solution no longer fizzed so I stopped, checked the solution it still shows very positive for Pd with stannous.


4. The same solution sitting for half an hour.



what should i do now?

Thanks
Kev


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## shyknee

Something is not right with your SMB mine is all ways clear in solution (when mixed with water).
check your source


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## kjavanb123

shyknee said:


> Something is not right with your SMB mine is all ways clear in solution (when mixed with water).
> check your source


Is your ratio of mixing SMB with water same as mine? 54g to 100ml of water?
Thanks
Kev


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## lazersteve

Kev,



lazersteve said:


> lazersteve said:
> 
> 
> 
> If you have a relatively clean Pd nitrate ( ie: no other precious metals) solution you can use SMB to precipitate the Pd metal and refine it a second time for higher purity.
> 
> 
> 
> 
> Correction.
> 
> I tried this yesterday and had mixed results. The result was a bright yellow powder that tested positive as a Pd salt, not a fine black powder as expected (Pd metal). I read the source literature again and noticed it said SO2 gas, not SMB so I figured the sodium ions worked to form a double salt with Pd instead of the metal as expected.
> 
> I added my SMB dry,* perhaps if I had dissolved it in a little HCl first I would have had better results. I also noticed I did not get any precipitate even after the SMB fully dissolved, until I added additional water.*
> 
> Steve
Click to expand...


I'm at a loss to understand why you keep adding enormous amount of acids and precipitants to your solutions in an effort to get the proper reaction. Again, you must start small at every step until you know what you are doing. *Learn how to repeat the reaction and get the same results every time before you scale up. * In chemistry more does not equal better. Have you ever had a glass of sweet tea or coffee with too much sugar in it?

A few grams of Pd only requires a few mL of nitric acid to dissolve and only a few grams of SMB to precipitate. Any more of either reagent is not only wasteful, but alters the overall reactions.

Your problem with the Palladium Nitrate solution is that it is most likely too dilute. You should have tried boiling it down before you added that much SMB. Unfortunately, now you have a saturated solution of SMB with a tiny amount of Pd in it so evaporation is not an option. I would try freezing the solution to see if the Pd will precipitate out at lower temperatures. Odds are you are going to get some sulfates mixed with the yellow Pd salt when you do. There is an off chance you can add *some* water and get the bulk of the yellow Pd to precipitate.* 

If all else fails I think you already know how to use the zinc recovery method. Be careful adding the zinc to the acidic solution with SMB (free SO2) present. You will very likely form sulfides and/or hydrogen sulfide which is a very deadly gas. * Hydrogen sulfide initially smells of rotten eggs until your sense of smell becomes dulled by it and then you no longer even know you are being exposed to this deadly gas until it kills you. The difference in concentration between the level at which you smell it at and the lethal dose is very small. With hydrogen sulfide, if you drop to one knee from exposure, you are most likely going to die from it. Please do not do this indoors or near animals, children, or in close proximity to any other occupied dwellings. *Gentle heating of the saturated SMB solution may help to drive off the SO2 gas. Definitely do this before adding any base metals or acids to the solution.*

Steve


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## kjavanb123

Steve,
Following your tips, i went ahead and heated the SMB saturated solution on a steam bath for few mins. Then slowly added small amount of zinc to it it turned dark as you can see from these pics.
The SMB saturated solution after SO2 emission using steam bath.



Same solution after zinc addition.



So i transfered it to a larger beaker, added 20% lye solution and as it turned out i had added too much zinc, then added boiling water, and 5% HCL and it looks like all the zinc removed and left is the black powder. which i will dissolve in nitric.
The black powder from processing 4 new honeycombs, i dissolved in minimal amount of nitric and steam bath to make sure it was saturated enough. then per your previous posts, i dissolved 4grams of SMB in few drops of HCL, then poured it in beaker containing Pd nitrate. lots of foaming and brown fumes, and this light brown color residue apperard which was gone to the bottom of beaker. I added total of 5 SMB HCL solution to the Pd nitrate, and filtered it. I am curios is this the right dark yellow Pd salt expected from SMB and nitrate solution?

Pd nitrate solution after addition of SMB HCL solution



SMB dissolved in small amount of HCL



Filtered residue and remaining Pd nitrate solution.



Please advise

Kev


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## freechemist

Reading through this whole thread again I see things which can go wrong and actually have gone wrong. I am sorry for not having given more detailed information together with my posted suggestions. Most important: palladium-refining, especially using nitrate solutions, has to be carefully planned and calculated as far as possible. Mixing palladium solutions, probably in fairly concentrated nitric acid with reducing agents like sodium-meta-bisulfite, even in small amounts, can become very dangerous through nearly explosive emission of toxic fumes (NOx) and foaming over and spilling of hot strongly acidic oxidizing and etching solution. In addition to this do not forget the palladium losses caused by such events.

Complex palladium sulfite salts, like the ones earlyer cited in my previous
post are formed only in nearly neutral solutions. That means, that most of all remaining acid has to be neutralized *before* addition of sulfite salts. This can best be done by adding carefully not too concentrated aqueous NaOH and controlling the pH-value. In the "Chemicals"-section I will post some more details about use of sulfite in palladium and gold-refining, as well as some details about the earlyer mentioned DMG in palladium-separation. 

Regards, freechemist


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## MarcoP

lazersteve said:


> lazersteve said:
> 
> 
> 
> If you have a relatively clean Pd nitrate ( ie: no other precious metals) solution you can use SMB to precipitate the Pd metal and refine it a second time for higher purity.
> 
> Steve
> 
> 
> 
> 
> Correction.
> 
> I tried this yesterday and had mixed results. The result was a bright yellow powder that tested positive as a Pd salt, not a fine black powder as expected (Pd metal). I read the source literature again and noticed it said SO2 gas, not SMB so I figured the sodium ions worked to form a double salt with Pd instead of the metal as expected.
> 
> I added my SMB dry, perhaps if I had dissolved it in a little HCl first I would have had better results. I also noticed I did not get any precipitate even after the SMB fully dissolved, until I added additional water.
> 
> More to come....
> 
> Steve
Click to expand...


Apologises to resume an old thread but after days of searching and coming up with unrelated or catalyst-about documents I felt not having much choice. I'm looking for the same literature, lazersteve could you point me to the right direction?
I'm trying to separate silver from palladium using SO2 to drop palladium and cementing silver with zinc or copper as already posted in the petrol gauge thread.


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## necromancer

you "may" find something here to help ??

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=51&t=18564


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## MarcoP

necromancer said:


> you "may" find something here to help ??
> 
> http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=51&t=18564


That's the same topic where I learned about it, if you look up the petrol gauge thread, http://goldrefiningforum.com/phpBB3/viewtopic.php?f=34&t=20886&p=225959#p225959 , you'll understand why I still needing to learn about the subject.
Thanks if I didn't know about that thread it would surely helped to get started.


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## necromancer

MarcoP said:


> necromancer said:
> 
> 
> 
> you "may" find something here to help ??
> 
> http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=51&t=18564
> 
> 
> 
> That's the same topic where I learned about it, if you look up the petrol gauge thread, http://goldrefiningforum.com/phpBB3/viewtopic.php?f=34&t=20886&p=225959#p225959 , you'll understand why I still needing to learn about the subject.
> Thanks if I didn't know about that thread it would surely helped to get started.
Click to expand...


yes, read them both, the link offered was a guess. maybe if you don't get a answer in a few days you can start a new thread on the subject :?:


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## MarcoP

Sure I could, on the mean time I get the right glassware and keep searching.


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## kurtak

MarcoP said:


> Apologises to resume an old thread but after days of searching and coming up with unrelated or catalyst-about documents I felt not having much choice. I'm looking for the same literature, lazersteve could you point me to the right direction?
> I'm trying to separate silver from palladium using SO2 to drop palladium and cementing silver with zinc or copper as already posted in the petrol gauge thread.



Marco

Due to the silver in the nitrate you will need to use DMG to "first" drop out your Pd 

The problem being (at least as I understand it from the research I have done) is that I order to drop Pd from a nitrate solution (with other then DMG) is that you need to change the PH of the solution from acidic to very near neutral before the PD will drop out --- so the problem is that in adjusting the solution from acidic to near neutral you will drop the silver out as a complex of silver (not elemental silver)

Edit to add ; - in other words - as long as the nitrate solution is acidic the Pd will just go back into solution as fast as it tries to precipitate with reagents other then DMG

Edit to add ; - Chloride (acidic) solutions are another story - which is why SO2 will precip Pd (at least in part) from an AR solution

Kurt


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## MarcoP

Thanks Kurt for the clarification. I just wanted to avoid the silver chloride route and the use of ammonia but it seems the there is no other easy way around.

As learned, DMG is a scavenger and should not be used to recover palladium, but instead it should be used to test the presence or precipitate traces of palladium. Here I'm only trying to follow the best practices possible, most of the times reading all different methods can easily get someone confused.

So unless I use silver metal to cement palladium with heat, time, stirring and patient (IF it will ever work due the tiny electronegativity difference of 0.3) ...I have to go the silver chloride method and cement palladium on zinc/copper.
Anyway I'll keep searching about this argument before going ahead.


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## solar_plasma

> so the problem is that in adjusting the solution from acidic to near neutral you will drop the silver out as a complex of silver (not elemental silver)



Wouldn't the precipitation of AgOH start at a pH of 8,3? Even though I learned that the pH range of hydroxide precipitation might be influenced by a lot of variables and is one of the poorest ways to part different metals, 8,3 seems to be far enough from acidic to near neutral and the only thing needed is, that the silver won't precipitate. Though I wouldn't bet my ... and choose the safest way with known results.


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## kurtak

solar_plasma said:


> so the problem is that in adjusting the solution from acidic to near neutral you will drop the silver out as a complex of silver (not elemental silver)
> 
> 
> 
> 
> Wouldn't the precipitation of AgOH start at a pH of 8,3? Even though I learned that the pH range of hydroxide precipitation might be influenced by a lot of variables and is one of the poorest ways to part different metals, 8,3 seems to be far enough from acidic to near neutral and the only thing needed is, that the silver won't precipitate. Though I wouldn't bet my ... and choose the safest way with known results.
Click to expand...


Solar

here is a picture of some silver precipitated by NaOH with the PH adjusted to near neutral (with NaOH) but still acidic

My 2 to 10 PH paper (sitting on top of the beaker) is telling me the PH is between 4 & 6

so I used a piece of my 5.5 to 8.0 range paper (sitting by beaker) & its telling me more like 6.2 maybe 6.4

The silver nitrate came from dissolving Ag crystals from my silver cell to make more electrolyte - when I dissolved the silver it was of course 50/50 nitric/water - not all the silver dissolved (which left some very fine silver sediment in the bottom of the beaker) so after I siphoned most the Ag nitrate for my electrolyte there was still some remaining in the beaker which was then diluted about another 50% when I washed the beaker walls down with my wash bottle - so it was normal 50/50 Ag nitrate diluted about another 50%

So at near neutral but still acidic the silver does precip - at least when NaOH is used to ajust the PH

Edit to say; - you have to look close to the left hand side the PH paper on top of the beaker to see the slight red (acidic) test of the 2 to 10 paper


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## butcher

Although metals do precipitate as hydroxides the range they do so can vary widely, it is not that they get to a certain pH and then just drop out of solution.

My guess here is when you bring the pH up closer to neutral (pH 6 to 7) some of the silver will precipitate as an hydroxide of silver, but much more when you get into the pH of around 9, all the way up to around pH 12 where the silver hydroxide will be the least soluble as a hydroxide.


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## g_axelsson

I haven't done any more experiments with precipitating Pd from nitric solution since that thread referenced above. I came to the conclusion that the precipitation was not good enough (but that could depend on pH) and going the silver chloride route was easiest. To put things in perspective, I'm not going to chase a few grams of a metal worth about 2.5% of palladium when I can recover that part later on from the wastes. My main focus is palladium and that is easiest to recover with zinc from the dilute solution after precipitating the silver with chloride and denoxing the palladium solution (evaporation to get rid of excess acid once and acidifying it with dilute HCl).
This process suits me well and that is what I'm going to use next time.

For treatment of silver chloride I usually treat it with NaOH to turn it into oxide / hydroxide, then dissolving it in nitric acid and cementing it with copper. Any leftovers of silver chloride is caught in filters and ends up in my burn pile for later processing.

Göran


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## solar_plasma

Very interesting and I think it is needed to reread this some more times to understand all consequences, I at least will have to.

Göran, I can hardly believe you didn't try the sugar method for silver chloride, so, what did you make chosing this way (chloride-oxide-nitrate-cementation)?


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## kurtak

butcher said:


> Although metals do precipitate as hydroxides the range they do so can vary widely, it is not that they get to a certain pH and then just drop out of solution.
> 
> My guess here is when you bring the pH up closer to neutral (pH 6 to 7) some of the silver will precipitate as an hydroxide of silver, but much more when you get into the pH of around 9, all the way up to around pH 12 where the silver hydroxide will be the least soluble as a hydroxide.



Correct - after adjusting the Ag nitrate to the near neutral I put a drop in my jar that contains HCl which I rinse my Ag nitrate beakers into to recover the traces of very dilute Ag in as AgCl & yes there is still Ag in solution so at near neutral some of the Ag starts to precip but it doesn't bring it all down - how high on PH you would need to go to get it all is another story

How concentrate (or dilute) is going to make a difference - as well as temp --- I figured this all out when testing Ag nitrate solutions with DMG that is prepared with NaOH - if the solution would get to dilute the NaOh would precip Ag (as well as Pd if present) but the Ag would not go back into solution like in a concentrated Ag nitrate solution

Anyway the point I was trying to make to Marco was that in order to precip Pd from a nitrate solution it is not as simple as just adding SMB &/or bubbling SO2 into the solution - but rather it requires PH adjustment & therefore other metals can become a problem - & PH adjustment is only part of it

Kurt


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## g_axelsson

solar_plasma said:


> Very interesting and I think it is needed to reread this some more times to understand all consequences, I at least will have to.
> 
> Göran, I can hardly believe you didn't try the sugar method for silver chloride, so, what did you make chosing this way (chloride-oxide-nitrate-cementation)?


I did try the sugar method and I felt it was messy. The way I'm doing it now suits me fine, my metallic silver powder is free from silver chloride. I never got a 100% conversion with sugar and the remaining silver chloride annoyed me. Also the waste liquids are opaque and I can't see if there are any sediments or the filtrate is clear.
If I do silver chloride my way I can filter / decant off the silver nitrate and any remaining silver chloride would be exposed when the nitric dissolved the silver oxide so I can repeat the process if there's enough left or just add it to the next batch.
One good thing is that I don't need to wash the silver in ammonia to remove silver chloride and all the inconveniences that brings.

The waste liquid can be put into the stock pot for cementing traces of pgm:s and collection of silver chloride. Any NaOH will be neutralized by the next addition of acid waste. I don't want to add any organics to my stock pot so the waste from the sugar method I would have to process separately.

Maybe I'm going to give the silver chloride and sugar method another go if I have a lot of silver chloride without traces of other precious metals, but currently the only silver chloride I get is from electronic waste and lot sizes are usually between 10 and 100g. A small beaker, treat it with NaOH, then washing and treating it with a few ml of nitric acid, then on to cementation, drying and adding it to my recovered silver powder.

When I have enough silver powder I'm going to run it through a silver cell to separate any PGM:s that have hitched a ride.

Göran


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## kurtak

solar_plasma said:


> Very interesting and I think it is needed to reread this some more times to understand all consequences, I at least will have to.



Solar

You will need to dig deeper then just this thread to even start to understand it (Pd in a nitrate solution) I have recently been doing a fair amount of research on it & still don't have my head wrapped around it - at least not to the point of playing with it yet - though I have learned a lot - at this point I need to start going over my notes & putting some order to them

Kurt


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## solar_plasma

Kurt, you're absolutely right and I am aware of it. After my first and only adventure with platinum, which worked, but I learned how messy it is, I am still not sure, if I ever want to get back to pgms. No, I was thinking of hydroxide precipitation in general. Reading all the texts here and on the net, one could easily get the impression, that it would work fine for parting base metals - nope, it won't, at least not to any point of satisfaction in most cases other than to show pupils one of many ways to treat industrial waste. At least this is my opinion today.

Göran, I knew, there must be a reason, why you chose this way. I appreciated the sugar method for making less volume of waste and not having to mess around with HNO3 more than absolutely necessary.


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## necromancer

sounds like a great reason to invest in LazerSteve's DVD


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## solar_plasma

When I started, I wanted to learn it all and if possible all at the same time. I got wiser. It's okay with microexperiments showing to the pupils, but every single process creates its own kind of waste. Specializing to a few processes saves me a lot of headache, I learned :lol:


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## kurtak

solar_plasma said:


> When I started, I wanted to learn it all and if possible all at the same time. I got wiser. It's okay with microexperiments showing to the pupils, but every single process creates its own kind of waste. Specializing to a few processes saves me a lot of headache, I learned :lol:



:lol: 

One of the things I like about all of this is just about the time you think you have it all figured out - you find out your not even close :mrgreen: 

My experience on this forum over the last 4 years has been :arrow: :shock: 8) :lol: :x    :evil: :twisted: :roll: :!: :?: :idea: :| :mrgreen: (did I miss any of them there faces)

Kurt


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## solar_plasma

So true! :mrgreen:


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## Barren Realms 007

kurtak said:


> solar_plasma said:
> 
> 
> 
> When I started, I wanted to learn it all and if possible all at the same time. I got wiser. It's okay with microexperiments showing to the pupils, but every single process creates its own kind of waste. Specializing to a few processes saves me a lot of headache, I learned :lol:
> 
> 
> 
> 
> :lol:
> 
> One of the things I like about all of this is just about the time you think you have it all figured out - you find out your not even close :mrgreen:
> 
> My experience on this forum over the last 4 years has been :arrow: :shock: 8) :lol: :x    :evil: :twisted: :roll: :!: :?: :idea: :| :mrgreen: (did I miss any of them there faces)
> 
> Kurt
Click to expand...


That's OK. you will find as you do it even longer and handle even more different item that you know even less but it does come together slowly with time.


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## g_axelsson

With knowledge you can ask the correct questions.

Göran


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## MarcoP

Thanks to you all I came to stick in my tick skull that, for now, I've got to eliminate silver before palladium or use DMG first, and then cement silver for last. After all the expected return should be ≤20%, remember this is a 8:2 Agd alloy.

I might also look into separating silver chloride, quickly switch from nitric to chloride at 80°C (176°F) by addition of hydrochloric [stt]and cotton balls. I believe putting a layer on top of the solution would also catch and suppress some NOx perhaps a slight excess would also behave as flocculant?[/stt]
Anyway after denoxing I could go the well known way as per Ms Hoke.

I never would have thought to have to deal with such quantity of palladium so early, e-waste will return much less.


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## kurtak

g_axelsson said:


> For treatment of silver chloride I usually treat it with NaOH to turn it into oxide / hydroxide, then dissolving it in nitric acid and cementing it with copper. Any leftovers of silver chloride is caught in filters and ends up in my burn pile for later processing.
> 
> Göran



Goran

thanks for the tip - I have always disliked the sugar part of the AgCl conversion for the same reason (sugar in the waste) I think I will give this a try the nexttime I am dealing with AgCl

when I think about it (now that you mention it) its like a "no brainer" -at least for small amount of AgCl

Kurt


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## solar_plasma

Just for the completeness, silver oxide can be reduced with H2O2, too.

Here is one link for those who are interested:  EDIT: and to those, who do not read the answers below: Lou says, *don't use this*, because of possible steam explosions

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=50&t=19249

I tried it once with a few gramm, but sugar is cheaper to me. For many it is getting harder to buy H2O2.


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## Lou

NEVER reduce silver oxide with hydrogen peroxide.

Too exothermic and likely to cause steam explosions. Silver catalytically decomposes peroxide.

Horrible idea for larger scale work.


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## necromancer

how about for small amounts ?? one troy ounce or less ??


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## Barren Realms 007

necromancer said:


> how about for small amounts ?? one troy ounce or less ??




If Lou says don't do it. Take it to the bank as gospel and don't do it in any quantity.


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## solar_plasma

> I tried it once with a few gramm, but sugar is cheaper to me.





> Horrible idea for larger scale work.



Thank you Lou, for the correction. That's good to know.


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## necromancer

Barren Realms 007 said:


> necromancer said:
> 
> 
> 
> how about for small amounts ?? one troy ounce or less ??
> 
> 
> 
> 
> 
> If Lou says don't do it. Take it to the bank as gospel and don't do it in any quantity.
Click to expand...


then i will comply , thank you !!


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## g_axelsson

You are correct Lou, now I remember that many semi professional rockets use a silver catalyst and hydrogen peroxide as the sole fuel. That's all!

Thanks for the warning!

This is what you get when mixing hydrogen peroxide with a silver catalyst. (Cut to 1.47 to get to the action)
[youtube]http://www.youtube.com/watch?v=hWxjUDEYIiw&x-yt-cl=84503534&x-yt-ts=1421914688#t=10[/youtube]

Göran


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## necromancer

now that's fast refining :shock: wonder what's in that guys under pants after taking off that fast.


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## Marcel

solar_plasma said:


> Just for the completeness, silver oxide can be reduced with H2O2, too.
> 
> Here is one link for those who are interested:  EDIT: and to those, who do not read the answers below: Lou says, *don't use this*, because of possible steam explosions
> 
> http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=50&t=19249
> 
> I tried it once with a few gramm, but sugar is cheaper to me. For many it is getting harder to buy H2O2.



Silver oxide will be reduced to silver simply by applying heat (+100°C). Did that the other day, worked like a charm.

Now it seems, that the photos are in the wrong order... :|


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## Research135

Hello all:
What alternatives are there to recover pure/impure platinum from nitrate solutions (palladium, platinum, silver, copper, nickel, zinc, traces of others), before recovering silver?. Order of metals given, approximate net values in $). Thanks.


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## FrugalRefiner

Welcome to the forum. 

Hoke provides some guidance in her book. You'll find links to it in my signature line below.

Dave


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## Research135

FrugalRefiner said:


> Welcome to the forum.
> 
> Hoke provides some guidance in her book. You'll find links to it in my signature line below.
> 
> Dave


Thanks Dave.
I wish to completely avoid the silver chloride route.
I can get the palladium with DMG.
Maybe I can drop the silver as silver oxide, and then go for the platinum?. That would work.

Is there another way to get the platinum out from solution quantitatively, before the silver?


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## Lou

Resin.


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## Research135

Lou said:


> Resin.


Thanks sir. Would you please ellaborate or post a link to that procedure?

Would sodium formate precipitate platinum selectively, or would the silver come down at the same time?.

Thanks in advance.


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## Lou

Silver will come down.


Probably easiest for you is to bring the pH up to 6.5, collect the Pd precipitate, rinse well with DI, acidify with HCl and then separate the Pd from silver chloride by rinsing with 2% w/v HCl solution until no more yellow rinses from the chloride filter cake.
Then you can cement it and save it until you have a few ounces worth to process.


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## g_axelsson

If you try to collect Pd at lower pH, will that break down the precipitate and oxidize the DMG?

At least that is what I suspect my first trial with DMG resulted in... The precipitate started to float and in a short while it dissolved again.

 

Göran


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## Lou

Assuredly so, Goran.

DMG really works best in solutions that are 0.5 M-3M in acid, preferably either nitric or in hydrochloric. DMG-Pd complex will dissolve in aqua regia or in HCl/Cl2.

Lou


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## Research135

Thanks for all the suggestions, but as I mentioned, I do not want to deal with silver chloride.

Is there a solvent selective for Pt(II) (preferred) or for Ag(I) (second choice) that will work with nitrate/nitric solutions?


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## Lou

Do you need to remove platinum (II) or palladium (II)?

Generally speaking, Pd is done with sulfides from chloride milieu, as nitrates will oxidize the s/x extraction agent so that's out.

What's the solution composition in g/L of these elements (inclusive of base metals)?


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## Research135

Original question:


Research135 said:


> Hello all:
> What alternatives are there to *recover pure/impure platinum *from nitrate solutions (palladium, platinum, silver, copper, nickel, zinc, traces of others), before recovering silver?. Order of metals given, approximate net values in $). Thanks.



The solution is about 87% silver nitrate, 1.5% platinum nitrate, 0.5-4% palladium nitrate, balance other metals mainly copper.

g/L will depend on the dilution/concentration. I try to keep water to a minimum.

Thanks.

edit: both platinum and palladium are valence +2, I believe, in this case.


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## g_axelsson

I'm no expert as I haven't done any solutions like this yet, but with those concentrations I would scavenge the Pd with DMG first, then cement silver and Pt with copper and run that through a silver cell to get pure silver out. Last I would treat the slime from the cell to get the platinum and refine it with standard methods when I got enough.

What I have read on the forum is that low level of platinum alloyed with silver could be dissolved with nitric acid. How about the anode slime? Is that fine enough to be dissolved in nitric alone or could the silver be dissolved with nitric while leaving most of the platinum undissolved?
Anyhow, the anode slime would contain a lot higher level of platinum than the original solution and platinum is a lot easier to work with when concentrated.

But my best advice is that when it comes to PGM:s Lou is the master here. If you follow his advice you can't go wrong. 8) 

Göran


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## Research135

Thanks Göran. I will investigate the "resin" suggestion by Lou. The other processes suggested are too time consuming, except the DMG treatment for palladium which is fast and simple.


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## Research135

butcher said:


> Although metals do precipitate as hydroxides the range they do so can vary widely, it is not that they get to a certain pH and then just drop out of solution.
> 
> My guess here is when you bring the pH up closer to neutral (pH 6 to 7) some of the silver will precipitate as an hydroxide of silver, but much more when you get into the pH of around 9, all the way up to around pH 12 where the silver hydroxide will be the least soluble as a hydroxide.


Hello. Do you have a chart like this, that also includes gold and the PGMs?. Thanks.


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## solar_plasma

Research135 said:


> butcher said:
> 
> 
> 
> Although metals do precipitate as hydroxides the range they do so can vary widely, it is not that they get to a certain pH and then just drop out of solution.
> 
> My guess here is when you bring the pH up closer to neutral (pH 6 to 7) some of the silver will precipitate as an hydroxide of silver, but much more when you get into the pH of around 9, all the way up to around pH 12 where the silver hydroxide will be the least soluble as a hydroxide.
> 
> 
> 
> Hello. Do you have a chart like this, that also includes gold and the PGMs?. Thanks.
Click to expand...


Read once more, what Butcher has told: "the range they do so can vary widely". Even though you find some charts, they will only be true in an accurately similar setting regarding concentrations, pH, ORP, temperature, contaminants and interfering ions, complexing agents and other compounds.

Page 20, Eh-pH Diagrams will give you an impression of a few facettes. *(Au, Pt, Pd and most other metals are also included, pages 32, 198, 190)* The concentration in those diagrams is set to 10-10 mole/kg or in my words: next to nothing. With concentrations of up to about 1 mole/kg things may be completely different.

If I find something closer to your case, I will post it here.

edit: german wikipedia (Hydroxide) tells that AgOH precipitates between pH 8,3-11,3. But as I said before, this can vary several pH'es up or down or becoming something completely different depending on the other influences, so you can't use this.


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## butcher

Many metals are also Amphoteric, they can preciipitate at one range of pH on the basic side and dissolve again as the solution becomes even more basic.
Separation of base metals using pH could be difficult at the very least least (depending on the metals involved) up to impossible as many of the metals overlap in their solubilitys at certain pH ranges.


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## kurtak

The resin Lou is taking about is on the order of this product :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=84&t=16948 

Also concerning PH adjustment :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=9058&p=226093&hilit=palladium+nitrate#p226025 read from this post down the next 7 or 8 post

Kurt


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## Research135

kurtak said:


> The resin Lou is taking about is on the order of this product :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=84&t=16948
> 
> Also concerning PH adjustment :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=9058&p=226093&hilit=palladium+nitrate#p226025 read from this post down the next 7 or 8 post
> 
> Kurt


Thanks a lot to all.
edit to add:
I'm finding it hard to login to the forum. It looks like a problem on the forum's server side.

FWIW, and I'm not recommending the procedure to anyone, since it is tedious and difficult, and not quantitative in its separations, this is a brief summary of how we process it currently:

1-Work with very concentrated, hot solutions, with very little excess nitric acid to begin with.
2-Add DMG dissolved in concentrated KOH. We watch the pH to always stay below 7. We drip extra KOH, if needed, to bring pH to almost 7.
3-Filter the Pd-DMG precipitate. Washing precipitate with plain water.
4-Add nitric acid to the filtrate to pH 0-1.
5-We add K2SO4 to the solution, and keep the heat on till most of the Ag2SO4 crystallizes/precipitates.
6-Filter the Ag2SO4.
7-Bring pH to 6 again and add concentrated potassium formate to drop the platinum black. Filter.
8-Cement with Cu the nitrate solution, and then recycle the nitrates to make nitric acid again.

I was hoping there was a magic ingredient to drop the platinum quantitatively that worked on platinum like DMG works on palladium.

The resin route seems too involved and expensive for all but the largest operations. Or that's my uninformed opinion.


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## Research135

sssshhhh!


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## kjavanb123

Hi,

I am dealing with 15 liter of silver (300grams), and palladium (6grams) nitrate solution. I add salt to precipitate silver chloride, filter it, and now for the palladium nitrate solution, based on the information exchanged here, I need to bring the pH to 6, then add SMB to drop Pd as yellow salt? Or does raising pH to that level make the Pd to drop as its hydroxide?

Best regards
Kj


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## Rougemillenial

The best suggestion I have for getting the palladium out would be dimethylglyoxime. Unfortunately the chloride drop will only work if the pH is higher than 5. If it's lower than that an equalibrium will form between h3o+, XCl and HCl, X+ spectator ions. The HCL will react with the nitrate to form crude aqua regia and form NOCl which will waste extremely expensive nitrate and possibly inhibit the dropping of the silver instead pushing the reaction towards nitrate and nitrosyl chloride. So the solution would have a significant amount of silver. Not to mention that silver chloride like gold won't drop out of solution at a low pH. The way to go if you can't make or buy DMG would be to raise the pH with a small amount of base, then use a bit of sodium sulfate to drop the lead out. Then you will have a solution that contains palladium, silver nitrate/sulfate, and copper primarily. The silver can then be dropped out with
Sodium chloride to form sodium nitrate and silver chloride. Once that's done, the palladium chloride remaining can be dropped out with copper metal. This leaves sodium nitrate and copper chloride in solution. You can save this to make nitric acid when it's needed thus saving costs. The reason why I would recommend this over a simple chloride drop besides the obvious selectiveness of the precipitation is the higher efficiency of the drop. Raising the pH allows the reaction to go to completion. However it does take longer than adding DMG and then dropping the silver out with copper metal. If you have access to say hydroxylamine monosulfonate sodium salt, MEK, and sodium nitrite I highly suggest you just make DMG. This process just applies to those who cannot easily get or make DMG. I hope this helps. Being an ametuer chemist, I usually have to use stuff at my immediate disposal. Hydrochloric acid from pool supply stores charcoal briquettes as gas scrubbing compound, Home Depot 5 gallon pails to do my reactions in, and enormous camounts of time designing reaction pathways and researching the millions of reactions transition metals and metaloids can do. I have to read the ingredients of common items and find ways to purify it to a point of being useful. However I do this sort of thing on a far larger scale than most refiners would do e-waste recovery on. I processed a few metric tons of material over 3 years. I am left with about 200 or so kilos of concentrates consisting of the PMS, copper, organics and ceramics. I did an assay and figured out that I had around 40oz a ton of precious metals. Though I could be way off due to my furnace breaking halfway through the melt. I managed to get a refund and my new furnace should arrive by Christmas.


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## Lou

Rougemillenial said:


> The best suggestion I have for getting the palladium out would be dimethylglyoxime. Unfortunately the chloride drop will only work if the pH is higher than 5. If it's lower than that an equalibrium will form between h3o+, XCl and HCl, X+ spectator ions. The HCL will react with the nitrate to form crude aqua regia and form NOCl which will waste extremely expensive nitrate and possibly inhibit the dropping of the silver instead pushing the reaction towards nitrate and nitrosyl chloride. So the solution would have a significant amount of silver. Not to mention that silver chloride like gold won't drop out of solution at a low pH. The way to go if you can't make or buy DMG would be to raise the pH with a small amount of base, then use a bit of sodium sulfate to drop the lead out. Then you will have a solution that contains palladium, silver nitrate/sulfate, and copper primarily. The silver can then be dropped out with
> Sodium chloride to form sodium nitrate and silver chloride. Once that's done, the palladium chloride remaining can be dropped out with copper metal. This leaves sodium nitrate and copper chloride in solution. You can save this to make nitric acid when it's needed thus saving costs. The reason why I would recommend this over a simple chloride drop besides the obvious selectiveness of the precipitation is the higher efficiency of the drop. Raising the pH allows the reaction to go to completion. However it does take longer than adding DMG and then dropping the silver out with copper metal. If you have access to say hydroxylamine monosulfonate sodium salt, MEK, and sodium nitrite I highly suggest you just make DMG. This process just applies to those who cannot easily get or make DMG. I hope this helps. Being an ametuer chemist, I usually have to use stuff at my immediate disposal. Hydrochloric acid from pool supply stores charcoal briquettes as gas scrubbing compound, Home Depot 5 gallon pails to do my reactions in, and enormous camounts of time designing reaction pathways and researching the millions of reactions transition metals and metaloids can do. I have to read the ingredients of common items and find ways to purify it to a point of being useful. However I do this sort of thing on a far larger scale than most refiners would do e-waste recovery on. I processed a few metric tons of material over 3 years. I am left with about 200 or so kilos of concentrates consisting of the PMS, copper, organics and ceramics. I did an assay and figured out that I had around 40oz a ton of precious metals. Though I could be way off due to my furnace breaking halfway through the melt. I managed to get a refund and my new furnace should arrive by Christmas.




Hey, welcome to the forum!

I really can't say I agree on making DMG unless it's a lot of it. The reaction isn't that straightforward, isn't that high yielding, and there's a lot of organic waste associated. Furthermore, DMG really is way too expensive to use for anything other than analytical purposes in my opinion. Also, DMG should not be used in the presence of gold!

For cheapness on high silver, low Pd, low base metal contaminated nitrate solutions, I stand by removing Ag as AgCl (and probably some PbCl2), rinsing the Pd assay off the filter cake w/ dilute HCl and alkalizing to concentrate the Pd as its hydroxide. Unfortunately, the hydroxide is difficult to wash and the complex sulfite really only works well with chloride free streams.

On high silver, high Pd nitric acid streams w/ a lot of base metals, it's best to again remove the silver as its chloride with excess HCl and filter that off. After that, an aqua regia solution is left behind. Adding saturated KCl solution and cooling will get K2PdCl6 which can be worked up in the usual way. 

Hope that helps!


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## Rougemillenial

Lou said:


> Rougemillenial said:
> 
> 
> 
> The best suggestion I have for getting the palladium out would be dimethylglyoxime. Unfortunately the chloride drop will only work if the pH is higher than 5. If it's lower than that an equalibrium will form between h3o+, XCl and HCl, X+ spectator ions. The HCL will react with the nitrate to form crude aqua regia and form NOCl which will waste extremely expensive nitrate and possibly inhibit the dropping of the silver instead pushing the reaction towards nitrate and nitrosyl chloride. So the solution would have a significant amount of silver. Not to mention that silver chloride like gold won't drop out of solution at a low pH. The way to go if you can't make or buy DMG would be to raise the pH with a small amount of base, then use a bit of sodium sulfate to drop the lead out. Then you will have a solution that contains palladium, silver nitrate/sulfate, and copper primarily. The silver can then be dropped out with
> Sodium chloride to form sodium nitrate and silver chloride. Once that's done, the palladium chloride remaining can be dropped out with copper metal. This leaves sodium nitrate and copper chloride in solution. You can save this to make nitric acid when it's needed thus saving costs. The reason why I would recommend this over a simple chloride drop besides the obvious selectiveness of the precipitation is the higher efficiency of the drop. Raising the pH allows the reaction to go to completion. However it does take longer than adding DMG and then dropping the silver out with copper metal. If you have access to say hydroxylamine monosulfonate sodium salt, MEK, and sodium nitrite I highly suggest you just make DMG. This process just applies to those who cannot easily get or make DMG. I hope this helps. Being an ametuer chemist, I usually have to use stuff at my immediate disposal. Hydrochloric acid from pool supply stores charcoal briquettes as gas scrubbing compound, Home Depot 5 gallon pails to do my reactions in, and enormous camounts of time designing reaction pathways and researching the millions of reactions transition metals and metaloids can do. I have to read the ingredients of common items and find ways to purify it to a point of being useful. However I do this sort of thing on a far larger scale than most refiners would do e-waste recovery on. I processed a few metric tons of material over 3 years. I am left with about 200 or so kilos of concentrates consisting of the PMS, copper, organics and ceramics. I did an assay and figured out that I had around 40oz a ton of precious metals. Though I could be way off due to my furnace breaking halfway through the melt. I managed to get a refund and my new furnace should arrive by Christmas.
> 
> 
> 
> 
> 
> Hey, welcome to the forum!
> 
> I really can't say I agree on making DMG unless it's a lot of it. The reaction isn't that straightforward, isn't that high yielding, and there's a lot of organic waste associated. Furthermore, DMG really is way too expensive to use for anything other than analytical purposes in my opinion. Also, DMG should not be used in the presence of gold!
> 
> For cheapness on high silver, low Pd, low base metal contaminated nitrate solutions, I stand by removing Ag as AgCl (and probably some PbCl2), rinsing the Pd assay off the filter cake w/ dilute HCl and alkalizing to concentrate the Pd as its hydroxide. Unfortunately, the hydroxide is difficult to wash and the complex sulfite really only works well with chloride free streams.
> 
> On high silver, high Pd nitric acid streams w/ a lot of base metals, it's best to again remove the silver as its chloride with excess HCl and filter that off. After that, an aqua regia solution is left behind. Adding saturated KCl solution and cooling will get K2PdCl6 which can be worked up in the usual way.
> 
> Hope that helps!
Click to expand...

good to know. hexchloropaladate is likely the way to go. I mentioned DMG due to selectivness. the problem with DMG is the price, how dangerous the production is, and how volumous the precipitate is. the issues surrounding the separation of palladium and silver is entirely solved by thinking outside the box. if you can't separate the palladium from the silver then separate the silver from the palladium. then the palladium can be cemented out with copper


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## patnor1011

Pd pretty much same price than rhodium. Who would have know that...


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## Lino1406

Palladium from nitrate solution can be precipitated safely by caustic helped with formalin (mostly as Pd oxide). In my experiments I found no evidence to explosive compound (unlike silver, so don't do that in the presence of it). "30 and more recovery procedures"


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