# Palladium problem, not melting, not dissolving.



## goldandsilver123 (Dec 19, 2015)

Hello,

I'm having a problem processing a dirty palladium, since I already processed several hundreds of grams of palladium I felt confidant to receive this batch to refine.

The person who gave me the "palladium" already tried to refine/recovery himself, tried to do the red palladium complex, (NH4)2PdCl6, which he got almost nothing, as seeing in this picture:




Then he made the yellow palladium complex, (NH3)2PdCl2, with ammonia and HCl, and tried to melt right away with a torch the complex!! He gave up here.

But this solid is not the usual "canary" yellow like the platinum salt, it's a mixture of yellow and grey and has borax like pieces, as can be seen here:




He gave me 265 g of this solid and around 12 L of a solution he claimed had the most palladium (he was expecting 400g). 

The solution does not look like it has much palladium, as is not dark like when palladium is present, and when tested with stannous chloride the spot looked almost like dilluted gold. Here's the solution:






What I've tried to do so far:

1) Calcine the solids to be able to melt

The temperature did nothing to the complex, looking the same through out all the heating, picture:



2) Reduce the solid with formic acid and NaOH

I took 10 g of the solids add NaOH and 50 mL formic acid, the solids become grayish, but with a sandy appearance, not looking like palladium to me, picture:




Continue


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## goldandsilver123 (Dec 19, 2015)

Formic acids solids:




3) Dissolve it with aqua regia

I took a little of the solids, put in a beaker with around 40 mL of HCl and 10 mL of HNO3, the clear solution took a yellow color and there was sand like solids in the bottom, pictures:






4) Melting the solids as they came

I took some of the complex and tried to melt as it came, it melts like when you try to melt silver chloride, makes a watery flux with appearance of a metallic bead in the middle, this is the crucible after:






I've not tried to dissolve it in ammonia, going to try that tomorrow.

Does anyone knows if this is palladium? Can it be a weird palladium complex?

This person worked many years with palladium, precipitating with potassium iodide, KI, and then burning the PdI2 with a torch.

I do not think he's lying about the palladium. The palladium source is scrap material.


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## NobleMetalWorks (Dec 19, 2015)

If I had to guess, and be really liberal with suggesting certain things happened I would guess this.

Someone attempted to recover Pd from something they believed had Pd, but spilled it on the floor of a barn, or garage with a dirt floor. So they carefully dug up anything that wet, including whatever rocks or flux or slag might be mixed in with the solution or mud. Not trusting that they could recover the values from the dirt, they found you. I bet the solution is what spilled, and the material that is suppose to be sponge really just dirt soaked in the same solution.

Anyway, you might try fluxing with Soda Ash to flux off any silicates because just ordinary soil probably has a lot of it, if that reduces the material by any significant amount it's probably dirt. I would probably roast the material first, then check to see if there is magnetic material that can be separated. Then a flux that will resolve the silicates and whatever known properties might be a problem. At this point you will probably find out this was spilled solution on a dirt floor. Then you can talk with the guy, explain what you think happened, and hopefully get a little honesty out of him.

And if not, give everything back and don't waste your time, effort and money. When someone isn't honest about the material, it's probably better to just walk.

Scott


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## goldandsilver123 (Dec 20, 2015)

NobleMetalWorks said:


> If I had to guess, and be really liberal with suggesting certain things happened I would guess this.
> 
> Someone attempted to recover Pd from something they believed had Pd, but spilled it on the floor of a barn, or garage with a dirt floor. So they carefully dug up anything that wet, including whatever rocks or flux or slag might be mixed in with the solution or mud. Not trusting that they could recover the values from the dirt, they found you. I bet the solution is what spilled, and the material that is suppose to be sponge really just dirt soaked in the same solution.
> 
> ...



Thank you for the answer!

I used soda ash, Na2CO3, to melt the solids and got metallic bead from that! It's absolutely ugly, but it's metal, there's also a huge amount of flux that I believe there's palladium either oxidized or just tiny droplets in the solidified mass.

From 265 g I got 49 g of ugly metal. There's HCl in the beaker.




I don't think it's dirty from the floor, when I tried to melt without carbonate I got nothing metallic, maybe it's some sort of palladium oxide, maybe sodium carbonate reduces the palladium oxide like it does to silver, they are in the same row of the periodic table, we can expect some similarities... What I don't know is if sodium carbonate dissolves the palladium like when melting with NaOH.

I dissolved the first bead in AR and got this solution:








The crucible was really beaten after the melting


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## NobleMetalWorks (Dec 20, 2015)

Looks like there is a lot of iron in the first metal bead, you might try roasting or if you are doing so longer, and then running a magnet through the material. The red solution looks like iron would, and when reduced it almost looks like ferric chloride. Did you do a Stannous test and what did it show?

I would ask them where the material came from, that sometimes can be very important. There might be elements or minerals that are causing issues with your attempts to recover values, I would have a proper assay done so that you know better how to move forward.

Scott


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## kurtak (Dec 21, 2015)

I think Scott is on the right path here with roasting & then smelting - however a small amount of iron in the smelt may actually be of benefit as a reducing agent so I am not sure I would worry about run a magnet over it - unless there is a LOT of iron - if there is no iron in it you might want to use some charcoal dust in the smelt as a reducing agent - that of course is assuming you are dealing with complexes (tartar also acts as a reducer in smelting)

I would start with the normal borax/soda ash flux but maybe go 40/60 instead of 50/50 & I would ad some fluorspar - do you think there is any ceramic involved (from say crushed CAT comb) if so you would also need some cryolite in the flux

Also you may want to ad some copper as a collector (silver could be used but is more of a problem to part the Pd from) with copper collector you could then dissolve with nitric & drop your Pd as the diamine (ammonia - HCl)

Your flux/slag when molten needs to be running good & "fluid" for good circulation in the crucible so the fluorspar for thinning is important

On the solution - have you tried cementing with zinc ?

Or as suggested by Scott - have it assayed - or - return to client

And now we can wait to see what Lou has to say :mrgreen: 

Kurt


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## goldandsilver123 (Dec 29, 2015)

Hello!

I rushed things to get a result till december 22, and here are the results:

The person didn't expect palladium from the solids at all, great misunderstanding, I did not processed the solids after melting them together, but when I took a sample and dissolved in aqua regia, the solution take a palladium coloration, I do believe there's a bit of palladium in this:



To the initial solution were added 200 g of zinc dust and HCl, here's the solution coloration afterwards:



the zinc + other metals + palladium were digested in aqua regia and precipitated as (NH3)2PdCl2

Here we can see that the solution really had just a tiny bit of palladium.



The complex were reduced with formic acid:



The melted sponge gave a tiny bead:



The bead weighted 0,9 g


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