Waste solutions

[Marcel]

Per the bold print - I am sorry but that just flat out is NOT true !!!

If you have mixed PMs (gold & PGMs) in a solution & you put a piece of copper in that solution the copper will NEVER selectively cement out one metal over that of another metal

In other words - it is NOT going to cement out the dissolved gold FIRST - then the dissolved palladium SECOND - then the dissolved platinum THIRD

It just doesn't work like that !!!!

I see you are using the electromotive series rather then the reactive series which flips the series of the metals (which metals are at the top & which ones are at the bottom - basically - though there is some variance)

You can NOT selectively cement mixed PMs from a solution !!!

Kurt

This is an interesting and detailed description of the process. I came up with it after making some observations when I had Pd and Ag in nitric solution without other metals involved, or at least only trace amounts. I tried to explain to myself how the step-by-step cementation of the metals occurred. However, I did not read about this process elsewhere, and I may have misinterpreted what happened.

The reason behind it was that it is rather difficult (at least for me) to separate Silver and Palladium in a nitric solution. At that time I did not have DMG or another reagent with similar properties at hand.

When I put the copper sheet in the nitric solution, the cementation started with a layer of a certain color. Shortly after that, I noticed another layer with a different color on top of the first one. So I tried to remove the copper sheet, whenever the first layer was finished indicated by the change in colors. )I assumed the first layer was built up by Silver). Unfortunately, I did not have the means to evaluate the exact composition. Later, when the molten metal was checked by XRF, it showed an increase in the concentration of Pd, which is where my assumption came from. However, it could have been a coincidence. Overall, this was not an easily reproducible procedure, and I would not encourage anyone to expect selective cementation of various dissolved metals one after another. These reactions are quite chaotic and unpredictable, especially if the solution contains multiple acids and different metals and is agitated.

 

[orvi]

This is an interesting and detailed description of the process. I came up with it after making some observations when I had Pd and Ag in nitric solution without other metals involved, or at least only trace amounts. I tried to explain to myself how the step-by-step cementation of the metals occurred. However, I did not read about this process elsewhere, and I may have misinterpreted what happened.

The reason behind it was that it is rather difficult (at least for me) to separate Silver and Palladium in a nitric solution. At that time I did not have DMG or another reagent with similar properties at hand.

When I put the copper sheet in the nitric solution, the cementation started with a layer of a certain color. Shortly after that, I noticed another layer with a different color on top of the first one. So I tried to remove the copper sheet, whenever the first layer was finished indicated by the change in colors. )I assumed the first layer was built up by Silver). Unfortunately, I did not have the means to evaluate the exact composition. Later, when the molten metal was checked by XRF, it showed an increase in the concentration of Pd, which is where my assumption came from. However, it could have been a coincidence. Overall, this was not an easily reproducible procedure, and I would not encourage anyone to expect selective cementation of various dissolved metals one after another. These reactions are quite chaotic and unpredictable, especially if the solution contains multiple acids and different metals and is agitated.

I wonder if all separations of PGMs were that simple as AgPd separation

Yes it happens, as these two metals are different, form different type of deposits etc... So they will cement in different ways and at different speeds.
But it need to be said, outcomes vary from situation to situation that greatly, many times this couldn´t be even conidered a technique for separation.

 

[MvK]

For the record, it's PlatinumGroupMetals aka PGM's.
Your stannous test looks more brown to me, which indicates copper.

My bad, i edited this to PGM. The brown stannous test started out more orange but you could be right. DMG test got me some percipitate but ofcourse there would be copper present.
Honestly i didnt know copper would show brown on stannous, usually i only test with stannous after dropping gold from AR.

 

[Martijn]

My bad, i edited this to PGM. The brown stannous test started out more orange but you could be right. DMG test got me some percipitate but ofcourse there would be copper present.
Honestly i didnt know copper would show brown on stannous, usually i only test with stannous after dropping gold from AR.

It's called a false positive with copper. And like with gold, you can test for such small traces that will be hardly measurable after precipitation.
with refining you are removing the bulk of contaminations, but always leaving traces behind, how much traces are allowed in the final product, depends on the customers demands.

Please do not edit your posts without showing what's being edited, the whole thread can become a mess and off topic by that change.

The reason behind it was that it is rather difficult (at least for me) to separate Silver and Palladium in a nitric solution. At that time I did not have DMG or another reagent with similar properties at hand.

Why not add HCl to get the silver out, and cement any Pd out on copper?

 

[MvK]

It's called a false positive with copper. And like with gold, you can test for such small traces that will be hardly measurable after precipitation.
with refining you are removing the bulk of contaminations, but always leaving traces behind, how much traces are allowed in the final product, depends on the customers demands.

Please do not edit your posts without showing what's being edited, the whole thread can become a mess and off topic by that change.


Why not add HCl to get the silver out, and cement any Pd out on copper?

My bad, i put it in the bottom of the post now.

 

[nickton]

Really? I tried it. So now I must have a lead containing solution. Maybe I'll use something higher on the list to try to extract the lead now. Or maybe use some sulfuric acid, which I know removes lead from ar.

Sorry about all these questions. I am a layman and so need a lot of this explained in layman terms.

I don't know how to use the quote feature either

 

[Yggdrasil]

Really? I tried it. So now I must have a lead containing solution. Maybe I'll use something higher on the list to try to extract the lead now. Or maybe use some sulfuric acid, which I know removes lead from ar.

Sorry about all these questions. I am a layman and so need a lot of this explained in layman terms.

I don't know how to use the quote feature either

But you could press reply to the post you are replying to. Now it is hard to know which one you are commenting.