Canary yellow powder conversion issue

[kjavanb123]

All,

In reference to my telecom boards post under the "Types of PM scrap" section, we did recover 10.330 grams of gold, and very dark brown solution of Palladium nitrate as we precipitated silver from it. As seen in the following photo,


I have sourced a bargain price DMG locally and percipitated the yellow powder from palladium solution by the DMG solution, here is the result canary yellow powder being filtered,


Then we washed the yellow powder to another bucket and added hydrochloric acid(30%), and added zinc powder while stirring this mix, it foamed and increased in volume.

After addition of almost 1.3 kg of zinc powder and gallon of hydrochloric acid I realized something is wrong, there were some yellow foam on top but solution has turned pail yellow which tested negative for Pd.

I filtered and washed the grayish powder which remained at the buttom of bucket as seen in photo,


I let that dry, took a sample of it and to test if it is zinc, added hydrochloric acid to it, no reaction, just a yellow in color solution appeared as seen in this photo,


Now, I have precpitated yellow powder and converted to Pd and melted with no issues in the past, but this is puzzling to me where is the Pd that we started.

Any steps or tests suggested? Thanks in advance.
Once I know the amount of Pd recovered from this lot "telecom boards", since we weighed the starting silver prior to smelting, we can estimate the amount of silver recovered from this lot also.

Best regards
Kj

 

[kjavanb123]

All,

We also tried prepared DMG solution, on a sample of copper palladium nitrate solution and upon addition of DMG solution, a black slime precipitate, picture below show solution on the left prior to DMG addition, and on the right, after DMG was added.



I guess I am better off ordering Superlig resins thank to Lou advise, in order to avoid all these issues.

Regards
Kj

 

[Lou]

If you're going to do Pd frequently from gold/silver free solutions, it's the way to go.

Up front, it's expensive but over hundreds of ounces of Pd it becomes one of the cheapest Pd refining methods.


Also, if I read your post correctly, and the blue copper nitrate beaker is your feed, I'd say that the main issue is that there is little to no Pd in your solution. Even a 100 mg/L Pd(II) will color the blue copper solution green as if it were nickel. At a gram or more palladium per liter, it's dark brown.

 

[kjavanb123]

Hi Lou,

Thanks for your comment. I will certainly have to get the funds to purchase Superlig system.

Any advise on our current Pd DMG conversion situation sir?

I mean worst come to worse I will add filter paper, solution which we add soda ash into to make it solid and grayish powder, to our next batch we smelt and recover it again.

Best
Kj

 

[Lou]

Most likely no Pd to be had in feed liquor (see above).

 

[kjavanb123]

Lou,

Thanks for your comment. I will try to dissolve a small amount of the grayish powder in nitirc acid and observe the result.

Well noted on color changes for copper nitrate solution with or without Pd presence.

 

[kjavanb123]

Hi,

Some update on this post. A sample of grat powder in the photo, was tested with nitric acid, and strangely no reaction.

I guess I have to resort to my last option which is smelt the gray powder along with dried solutions.

Regards
Kj