Want To Recover Palladium With Silver

[jaun]

Hi fellow refiners,

I want to try something new, and want to know what you think:

I want to recover the palladium with silver from:
Palladium pins (from old IBM boards) and ceramic capacitors. (I will have to deal with: Pd, Ni, Cu, Pb, Sn, Ag, and others?)

Everyone process it with AR, and then the ammonium chloride and sodium chlorate method. I want to use nitric.....

I want to precipitate (Cement) it out with silver:

I dissolve everything in nitric, filter or decant solution – then I dilute with distilled water.

I then add silver powder I obtained from cemented silver to precipitate (cement the palladium).
It’s almost the same as cementing silver with copper.

You can then recover the silver again for reuse, (the same as inquartation in carat gold refinery)

I know I’m missing something here????
Any help will be appreciated,
Thanks
Jaun

 

[4metals]

The oxidation potential difference between silver and palladium is very small, as in 0.03 volts. While it should work in theory, in practice is another thing. It may take a very long time.

 

[jaun]

Thanks 4metals, figured something like that.

I’ll just use copper then, if there’s any silver in there, it will cement out with the Pd.
To separate silver and palladium is easy.

Thanks again
Jaun

 

[flexyman]

Hello Jaun,
Are you Still following the forum? I have several kilos of Silver/ Palladium
that I have cemented out of Nitric solution. Now I have washed microfine
metal powder. which is a combination of Silver and Palladium. How can I separate these two metals from each other? I do not want to re-disolve the metals again in chloride leach, is there another way.


flexyman

 

[Harold_V]

I have several kilos of Silver/ Palladium that I have cemented out of Nitric solution. Now I have washed microfine metal powder. which is a combination of Silver and Palladium. How can I separate these two metals from each other? I do not want to re-disolve the metals again in chloride leach, is there another way.

It's not all that difficult. Cast anodes and part the silver in a silver cell. The palladium will remain in the slimes unless you allow the level to climb too high in your electrolyte.

Assuming you part the silver and find you have traces of palladium in the (silver) crystals you recover, you can part the silver a second time, using fresh electrolyte, simply by placing the crystals in the anode basket, then placing another anode on top to act as a connector.

Make your electrolyte from harvested crystals that have been well washed. If there's any palladium included, it will show in the color of the properly prepared electrolyte. I used no copper in mine, so the solution when all of the nitric had been consumed had but a hint of yellow to its color. Any palladium that may be present would manifest itself as a green to brown color, depending on the amount present.

Harold

 

[flexyman]

Thank you Harlod,
How will I stop the Palladium from going into solution ? I refer to your note
( The palladium will remain in the slimes unless you allow the level to climb too high in your electrolyte.)
Refering to colors of electrolyte
Green = trace amounts ? Brown = large amount ?
or is it Green when electrolyte has both Silver and Palladium in solution
Brown when only Palladium is in solution.

thanks again Harold

 

[Harold_V]

Thank you Harlod,
How will I stop the Palladium from going into solution ? I refer to your note
( The palladium will remain in the slimes unless you allow the level to climb too high in your electrolyte.)

I phrased that rather poorly, it appears. Lets try again.

My experience with palladium, as I recall (it's been years), is that some goes in to solution. You can verify that by testing, but you can also verify visually---it shifts the color of the electrolyte towards green. The typical silver cell has so much copper present that it tends to be blue. As the solution darkens, it will start depositing some palladium. I had that experience one time, when the volume of palladium was so high it left behind a thick rather solid coating on the anode (hard black slime that had to be scraped--it would not shed). The coating acted much like silver chloride does when you're trying to dissolve gold with AR---it isolates the silver in the anode from the electrolyte---eventually lowering the silver content in the electrolyte and beginning to co-deposit palladium. Silver depletion is one of the problems you face when the balance of silver to other metals is not good.

If, when parting an anode, you find the slimes shed easily, pretty good chance palladium won't be much of a problem. I'd verify purity (if you have no other means) by making electrolyte from each harvest. I believe I already talked about the need to consume all of the nitric---which in and of itself will yield an electrolyte that has a slight green tint, assuming the electrolyte is made of pure silver. Covering the electrolyte with a watch glass, and heating, in the presence of a small amount of pure silver, assures that you consume all of the nitric, and the prolonged heating (to a controlled low boil) ejects any of the entrapped gasses. Such a solution, when pure, ends up being ever so slightly yellow, with no hint of green.

If you have doubts about the presence of palladium, a test with DMG is in order. It is VERY sensitive to palladium, disclosing extremely small amounts in solution.

Palladium dissolved in nitric yields a very dark brown solution. Even traces discolor a solution, so when you see a hint of green, you should always test for the reason. It is very unlikely you would ever create an electrolyte that turned brown from use---it would have long before started producing less than acceptable silver.

Best way to start understanding any of this is to get involved. You will learn from each experience, but don't get started until you have a firm understanding of what you must do, and how. Study first, then apply what you learn.

Harold

 

[flexyman]

Thanks again Harold,
I have learned a great deal.
I was getting co-plating of the 2 metals now I have rectified the proceedure.

 

[jaun]

Hi Flexyman,

Sorry for the late reply, (was offline for a while)

If you don’t want to dissolve the Pd in a chloride leach, then the method Harold explained is the only other method I can think of.

Here are 2 methods I have done before, but it involves dissolving the metals:

1. Dissolve Ag and Pd in nitric. Add HCL or table salt to precipitate silver chloride. Decant Pd solution. Convert silver chloride to elemental silver with any of the many methods on the forum. Refine Pd with the ammonium chloride and sodium chlorate method, or recover the Pd with steel wool.

2. Add AR to your Ag and Pd powder. Your Pd will go into solution (decant your Pd solution), leaving your silver behind. Some silver chloride will form, but you can convert that back to elemental silver. I just add some HCL and aluminium or steel wool, and it converts the silver chloride that formed back to elemental. (Or use caustic and kyro syrup)

Experiment and choose the method that works best for you. And remember - keep save.

Regards
Jaun

 

[Sucho]

Jaun

to your first method - there is a visible ammount of PdCl2 mixed with AgCl when you are precip. AgCl ( AgCl isnt snow-white but it has a brownish tint)
i recommend to wash your AgCl with HCl thoroughly.you will end with nice snow-white AgCl and brownish HCl.

 

[jaun]

Hi Sucho,

Yes u are right. Sorry, I should have mentioned how important washing the AgCl is.

I clean with HCL like you said, decant in a beaker and then wash 3 more times with water (decanting the water washes into the HCL) I then add steel wool to precipitate the Pd, you will be surprised how many Pd was left in the AgCl.

Remember to wait for the AgCl to settle before decanting, the solution will be coloured but must be must be clear, this takes some time.

I’d use method 1; method 2 is just unnecessary added steps

Regards
Jaun

 

[flexyman]

Hi Jaun,
Great to see you are still active on this forum.
When You first joined on the forum, you had some very interesting process on precipitating Pd with pool chemicals. I cannot find your proceedure on the forum, will you please PM me.
Back in RSA when I processed Telephone exchange relay buttons I used to
Heat any Ag and Pd mixed buttons to cherry red with a very Oxidizing flame.This gave the Pd a Peecock blue ( Pd oxide ) coating that stopped the Pd from disolving by dilute Nitric. then I easily separated Pd from AgCl.
From Rusternberg Plats. I learned the when Ni and Pd were in Nitric together
it was difficult to separate the two. A resin is used to remove the Ni, then
Pd is precipitated the usual way.
I buy Nitric very cheaply but It is a 250 mile( 300km ) round trip to fetch it then those nasty brown fume to content with . I have discovered that when I treat my Ag/Pd cement with an alkaline Chloride leach the Pd goes into Solution, then I decant the solution, wash the AgCl several times with hot water.I put the Pd solution in a Solar evaporator and remove excess water,the boil with HCl then precipt as usual. Oh! only use distilled water as this is easyier to evaporate away, no tap water.
When Hydrogen Sulfide is bubbled thru acid leach certain metals form Sulfides, When HS is bubbled thru a neutralized leach a different set of metals turn to sulfides.

Hope this throws a new light