# PG metals and DMG...



## samuel-a (Sep 5, 2011)

Beside Pd, will any other PG metal form an insoluble complex in acidic conditions?


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## Lou (Sep 5, 2011)

No.


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## samuel-a (Sep 5, 2011)

Thanks Lou.


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## Kats12 (Sep 5, 2011)

Nickel is know to form complex with DMG - "Brunuck-Chugayev" procedure for gravimetric analysis of Nickel. Of course in weak acids(acetic acid and formic) and ammonia. It is forming pink-red voluminous precipitate. Since youre are dealing with mlcc ,for example when you want to precipitate Pd from mlcc with DMG , if you are not careful you might get co-precipitation of Ni. normally Pd-DMG complex is yellow if other color is present then you got some Ni-DMG in it(for mlcc)...
fortunately Ni isn't Precious ;-D


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## samuel-a (Sep 5, 2011)

Hi Kats12 

I'm aware of Ni DMG complex could not exist in highly acidic solution.

At the moment, i'm not working with MLCC's and have no concern with Ni.

At first, DMG dropped the Pd as usual (orange juice pulp - look alike), soon, the precipitation turned very dark brown.

At this point i filtered the Pd-DMG and added again DMG to the filtered solution, this time only a dark brown/dull red precipitate formed, this time it setteled very quickly (similar to AgCl does), pH at 0-1, SnCl show definite black (with no other colors).

I'm really struggling here....


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## Lou (Sep 5, 2011)

Dissolve the ppt in ammonia and filter?


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## Kats12 (Sep 5, 2011)

> Dissolve the ppt in ammonia and filter?



I agree...
also You might look at these...
http://www.freepatentsonline.com/3922330.html
Maybe this might help You...
It's a little-bit messy but is useful

and these basic is also useful 
http://www.cpachem.com/en/Clas/Pd-grav.asp

best regards 
Kats


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## samuel-a (Sep 5, 2011)

Lou said:


> Dissolve the ppt in ammonia and filter?



How would you expect it to help in this current situation?

The reason i ask' is that some weeks ego, my small chemical fridge passed away, so i couldn't store my ammonia and the weather here is very hot.
I can make a fresh batch of 3-4N ammonia solution, but i'm thinking, maybe just better go ahead burning the Pd(DMG)2 (and the darker stuff) at 600-650C and further study a sample of sponge...

Penny for your thought...

Thanks.


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## lazersteve (Sep 6, 2011)

I have an article that mentions DMG and another reagent being used together for detection Rh and other metals.
I'll look up details and post them here.

Steve


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## samuel-a (Sep 7, 2011)

lazersteve said:


> I have an article that mentions DMG and another reagent being used together for detection Rh and other metals.
> I'll look up details and post them here.
> 
> Steve



Sounds interesting Steve.

I snapped a photo of the dry dark ??(DMG) complex:



In the meanwhile, i burned it to remove carbon and melted 0.5g test... it had all the characteristics of Pd.
The rest is back in AR to see if all dissolve or not.


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## freechemist (Oct 10, 2011)

Hello Sam,

To me the dark precipitate on your foto from September 7th looks like finely divided [Pt(HDMG)2], formed by slow reaction of dissolved Pt(II) with dimethylglyoxime. A method used at my active refining times to determine Pd and Pt quantitatively after inquartation, was to dissolve the Pd and Pt- containing Ag-buttons in ca. 32% HNO3 and to measure their Pd/Pt-contents by ICP after appropriate dilution. An alternative way was, to determine Pd gravimetrically by precipitation with dimethylglyoxime. This method is rather unsure because dissolved platinum reacts with H2DMG too, forming slowly insoluble [Pt(HDMG)2], which adds to the [Pd(HDMG)2]-precipitate, thus falsifying the result for Pd. Pure [Pt(HDMG)2] forms fine, dark chocolate-brown, nearly black needles with a violet, metallic glister. All three
precipitates, [M(HDMG)2], where M = Ni, Pd, Pt, are isomourphous, i.e. they have the same cristalline structure. 

Regards, freechemist


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## samuel-a (Oct 10, 2011)

Very interesting freechemist.

That's sound reasonable to me, thank you.

The only reservation i have from your description is that the dark ppt, formed instantly right after the orange DMG complex, but who knows... right?

Anyhow,few weeks back, i incorporated the DMG step to all of my solutions after inquartation and before the waste bucket.
I add few drops of DMG solution to each solution, both, nitric + Ag and AR without the gold.

The Pd/Pt really accumulate this way....


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## Lou (Oct 12, 2011)

Lou said:


> No.




I should correct myself to say that maybe some platinum complex is formed if the platinum is high in concentration, the solution warm, and it is Pt(II).
It is not typically the case, however.


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## freechemist (Oct 19, 2011)

If an alcoholic solution of dimethylglyoxime is used to precipitate palladium, there is ample reductant to reduce Pt(IV) to Pt(II), if not to the metal.

Regards, freechemist


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## Lou (Oct 20, 2011)

That is why I use DMSO.


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## HAuCl4 (Oct 21, 2011)

Is it safe to say that ALL the Pd will be scavenged as the DMG-Pd compound, but will be somewhat contaminated with platinum ?. :?: 

Something similar happens in Au-Pd chloride solutions, i.e.: The DMG forms a compound with gold too if gold is highly concentrated, but all the Pd comes down first, or that's my experience.


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## Lino1406 (Jun 20, 2018)

Rhodium also has DMG complex. When it is present in solution with palladium the complex will look much less yellow, white-grey hue. Anyone can confirm?


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## Inter Refiner (Apr 21, 2021)

Lou said:


> Lou said:
> 
> 
> > No.
> ...


I dissolve my pgms in hcl/h2o2 how could I get pt IV rather than pt II, I had the same problem
With dmg


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## orvi (Apr 22, 2021)

I also struggled to selectively ppt Pd with DMG. even in very acidic conditions. stock soln contained Pd/Pt/Rh, and I was aiming to scavenge P for Pt/Rh separation tests and XRF shown that Rh gone with Pd to the ppt.
Rh wasnt detectable in any further step of processing even that it was clearly shown in the stock soln. (0,6%)
and also nearly half of platinum gone as well. i used DMG somewhat suspended in DMSO (aim to try this approach and failed miserably  ). 
i have encountered Pt(II) few times in my short refinig career  mainly the difficulty to precipitate it with zinc in presence of copper and iron also in solution. processing large batches of old PtPd MLCCs i observed that Pd is immediately dropped by zinc dust when added, but somehow the majority of the Pt in solution wasnt in +4 ox state (no drop of salt with NH4Cl) - perhaps, this idk for sure. Because i added like twofold excess of zinc than usual and still no precipitation and XRF together with SnCl2 shown clearly Pt positive solution. prolonged stirring w zinc dust finally almost completely neutralized the HCl  not to mention the shit ton of Fe and Cu powders... and then it finally left the solution. addind shitton of HCl to get some of the base metals sludge back to the liquor...  because of this i clearly remember that strange Pt behavior


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## butcher (Apr 22, 2021)

Being below hydrogen in the reactivity series of metals, a metal like zinc can displace the hydrogen from the acidic solution basically in a manner neutralizing the acid forming salts ...


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## orvi (Apr 27, 2021)

yes, i completely understand the reactivity series and also that dropping PGMs on zinc isnt the most efficient process in acidic solution...  but with very strong mechanical stirring and slow zinc additions, i always managed to drop Pd very quickly. but not the Pt, platinum take some time to precipitate. in my case


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## zacchy (Sep 26, 2021)

Lou said:


> That is why I use DMSO.



Lou para que usas en DMSO? (Dimetil sulfóxido)


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## Lou (Sep 27, 2021)

It dissolves dimethylglyoxime like sugar into water and can be added to solutions to scavenge Pd. Be careful handling it! It will readily go through the skin.


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## FrugalRefiner (Sep 27, 2021)

Lou said:


> It will readily go through the skin.



And carry other dissolved chemicals with it.  

Dave


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## angga996 (Sep 27, 2021)

hello sir. I'm just learning to do precious metal refining for the first time. I soaked the capacitor that I burned, but the water was brown. my water is still in hno3 and using potassium hydroxide to do the precipitation. what precious metal is in my hno3 content sir. Thanks


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## kjavanb123 (Oct 1, 2021)

angga996 said:


> hello sir. I'm just learning to do precious metal refining for the first time. I soaked the capacitor that I burned, but the water was brown. my water is still in hno3 and using potassium hydroxide to do the precipitation. what precious metal is in my hno3 content sir. Thanks



Check your solution with stannous chloride testing solution.


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## Yggdrasil (Oct 1, 2021)

I really do not know why, but lately there has been a lot of posts where the op try to precipitate gold or PGMs with some kind of hydroxide.
I wonder if someone on the youtube has had a few videos with something like that.
Sure enough you can precipitate hydroxides by adjusting the Ph but I think that in most cases hydrolysis are more complicated than using smb, ascorbic, oxcalic or similar.

And here we have a language barrirer I assume, but we do not burn capacitors. We can heat them to red hot to remove organics and volatiles. But that is only done to ceramic capacitors and similar stuff, the op has not given any indications on what kind of capacitor he "burned" and thus we can not estimate if he have any PMs in there.

He has not given much info on what he has done to leach them other than indicate he has used dilute Nitric, but again without presise information we just can guess this. And as such we can not advice for or against any thing since vital information are missing.

As Kjavanb says, if he use stannous he can get an indication wheter or not his "water" contains values.
But nothing can help us estimate if he has lost values on the way, since his process is still a mystery.

So please tell us excactly what you have done and what your starting material was, then we can give some advice.


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