Cementing palladium on copper

[sayf]

Hello every one, i hope you are all doing well.
I have palladium dissolved in nitric acid with copper
Am out of DMG now, so am thinking about cementing palladium using cupper bars
Here is my question :
Do i need to add HCL to the nitric acid then to denox the nitric acid to get palladium chloride solution then to precipitate the palladium using copper.
Or, can i precipitate palladium directly from the nitric acid using copper bars ?
but this way i think the nitric will redissolve the precipiated palladium again.
So what Do you suggest dear refiners?
regards

 

[FrugalRefiner]

You can cement directly from the nitric solution. If you have a lot of excess nitric acid in the solution, yes, it will redissolve the palladium, until the excess of nitric is exhausted. Palladium can be a little problematic to cement unless you have good circulation running over the copper. If not, the copper can become coated with tightly adhering palladium, which will stall the cementation.

Read through the When In Doubt, Cement It Out thread. There is a link in the first post to a thread where Kurtak ran into the problem when cementing palladium. 4metals got him on the right track and solved his problem.

Dave

 

[orvi]

Copper PGM cementation is quite hard to do it right on the first time. It isn´t that quick, it needs aeration to chew up the copper underneath cemented Pd to fall off etc. But once you have the cementing rig set up, it is a piece of cake altough it tend to drag significant copper to the ppt. Always be sure that you have plenty surface area of fresh copper still in solution, otherwise CuCl2 re-dissolve your cemented PGMs back in solution.

If you don´t have Ag in solution, reduce the Pd with formate.

 

[FrugalRefiner]

Always be sure that you have plenty surface area of fresh copper still in solution, otherwise CuCl2 re-dissolve your cemented PGMs back in solution.

So far, he just has a nitrate solution, so CuCl₂ wouldn't be a problem in this case.

Dave

 

[orvi]

So far, he just has a nitrate solution, so CuCl₂ wouldn't be a problem in this case.

Dave

True it was too late for writing I assume... I would be better sleeping than writing advices

 

[sayf]

You can cement directly from the nitric solution. If you have a lot of excess nitric acid in the solution, yes, it will redissolve the palladium, until the excess of nitric is exhausted. Palladium can be a little problematic to cement unless you have good circulation running over the copper. If not, the copper can become coated with tightly adhering palladium, which will stall the cementation.

Read through the When In Doubt, Cement It Out thread. There is a link in the first post to a thread where Kurtak ran into the problem when cementing palladium. 4metals got him on the right track and solved his problem.

Dave

Hi dave, thank you for your reply.
i did read the whole thread it was very informative and liked your detailed way in explaining the cementation set.
I have a little note about the metals used to cement other dissolved metals. You said they should be soluble in the solution. But i used copper many times to drop gold from chloride solution after denoxing the excess nitric. And of course you know that copper is not soluble in HCL but it managed to precipitate the gold.

 

[orvi]

Hi dave, thank you for your reply.
i did read the whole thread it was very informative and liked your detailed way in explaining the cementation set.
I have a little note about the metals used to cement other dissolved metals. You said they should be soluble in the solution. But i used copper many times to drop gold from chloride solution after denoxing the excess nitric. And of course you know that copper is not soluble in HCL but it managed to precipitate the gold.

Copper dissolves because gold is replaced by it in solution. That dissolution of copper isn´t caused by acid, but by displacement of more noble gold from solution.

 

[FrugalRefiner]

You said they should be soluble in the solution. But i used copper many times to drop gold from chloride solution after denoxing the excess nitric. And of course you know that copper is not soluble in HCL but it managed to precipitate the gold.

You are correct that HCl on it's own doesn't do a good job of dissolving copper. But CuCl₂ is a very effective solvent for copper. So, copper works well to cement values from a chloride solution. As Orvi has said, it's not the HCl that's dissolving the copper, it's the metal chlorides that are doing the work, just as in a CuCl₂ (AP) leach, it's not the HCl that's dissolving the copper, but the CuCl₂.

Dave

 

[eshane211]

Copper PGM cementation is quite hard to do it right on the first time. It isn´t that quick, it needs aeration to chew up the copper underneath cemented Pd to fall off etc. But once you have the cementing rig set up, it is a piece of cake altough it tend to drag significant copper to the ppt. Always be sure that you have plenty surface area of fresh copper still in solution, otherwise CuCl2 re-dissolve your cemented PGMs back in solution.

If you don´t have Ag in solution, reduce the Pd with formate.

Hello hope all is well!! What is your process for reducing palladium with formate?

 

[orvi]

Hello hope all is well!! What is your process for reducing palladium with formate?

https://goldrefiningforum.com/threads/agpd-contacts-refining.31589/