Palladium in waste solutions

[stefano]

Hello at the members of this formidable forum.

First excuse my bad english. I can read and understanding the most things, but i can not write very well.

I have searched a lot on the net, on Hoke and here on the Forum for detecting and recovery of potential palladium in waste solutions. But dont´t found nothing.

I have three different stock pots. One is for used cucl2-bubbler-solutions ( i don´t work with h2o2 ). Another is for spend solutions from the crock pot method with hcl,( no h2o2 used ). Another is for rinsing solutions from nitric leaches and ar.
The first and the third stock pot are not a problem. The recovery of potential palladium is explained very well on Hoke or here in the forum.
But on the spend solutions from the cock pot i am very insure. I dissolved with the crock pot method any type of electronic scrap, and all base metals, which could be found in electronic scrap. Of course in the solution is a lot of tin chlorides like sncl2 and sncl4 and perhaps other tin compounds.
I know very well what happens when gold chloride and stannous chloride are getting mixed. Now the gold don´t dissolve in the crock pot, and therefore i have no gold colloids in my stock pot. But i read often that palladium can dissolve in hcl-base metal solutions, if these solutions are not saturated with base metal. What happens with dissolved palladium ( in hcl ) when it gets mixed with stannous chloride ? Is the result a colloid ? How can i recover potential dissolved palladium of these solutions ?

greetings from stefano

 

[nickvc]

Welcome to the forum Stephano.
Palladium will dissolve in HCl but only if it's finely divided from what I recall, the simple way to find out is to test with stannous, if as you say you have been dissolving base metals then any Pd should have cemented out and be mixed with the powders in the bottom. I think you know how to recover those values but if not then incinerate and put in HCl and heat, this should remove most of your base metals leaving you to chose the method of recovering and refining your values, test your HCl to check you have not dissolved any Pd.
Good luck and happy recoveries.

 

[UncleBenBen]

Wouldn't incineration oxidize finely divided Pd, making it more soluble in HCl?

Or did I remember that completely backwards?

 

[butcher]

http://www.theodora.com/encyclopedia/p/palladium_chemistry.html
Pd₂O insoluble in acids.
https://en.wikipedia.org/wiki/Palladium%28II%29_oxide
PdO insoluble in acids, slightly soluble in aqua regia.

 

[stefano]

Hello and thanks for the information.

But now i am more insure than before.

Butcher wrote in 2013 ( i don´t remember the topic ) :
Palladium metal or powders will dissolve in dilute nitric or ar.
Palladium oxide will not dissolve readily in dilute nitric or ar.
Palladium metall will not dissolve in hcl ( unless strong oxidizers are added ).
Paladium oxide will dissolve in hcl.
In Hokes book we learn we can take a mix of palladium oxide and palladium and put them both into solution, by heating hcl and adding it to these powders, which will put the palladium oxide into solution ( but not the palladium metal powder )...

I think that i can recognize considerably desagrees in all the discussions which concern the palladium processing. Perhaps there are a lot of experiences in this processes, but at me the palladium recovery process seems to be very much difficult and complicated than the recovery process of gold.

I think that i want to try to concentrate my waste solutions, than trying to cement with copper what could be cemented, and disposing the rest without looking for potential values.

Great thanks for all your topics and discussions. This is a great forum.

Greetings from stefano

 

[butcher]

Maybe this will help, some metals can form different oxides, and have different valences, with can react differently to acids.
Much can depend on the condition of the oxide (or even how it may have been formed)...

 

[Lou]

Slow your roll and test with alcohol dimethylglyoxime to see even if you have substantial Pd in solution.

Lou