# Palladium precipitation



## Rem123 (Apr 18, 2021)

Hi everybody. I have a green palladium solution. I took a sample of it and I added a DMG and sodium hydroxide solution to the green pd solution. It precipitated green powder. I read in some forums that I should filtrate the powder and wash it with cold water until it gets yellow pdDMG powder. When I washed it it got white color. Am I doing something wronge? Or I didnt make the DMG solution correctly. I tested the green solution with Stannous chloride before and after adding DMG solution. Before it was positive after adding it got negative with the green precipitate. What should I do?


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## Lino1406 (Apr 18, 2021)

No yellow, no Pd. What is the source?


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## Geo (Apr 25, 2021)

You may have neutralized all of the acid and made the solution basic. Any copper or other base metal that forms a green salt would drop out.


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## Rem123 (May 8, 2021)

I took a sample of the precipitate and dissolved it in AR and stannous tested it and it was positive for palladium. When I added sodium hydroxide a brown precipitate settled on the bottom. Is this palladium hydroxide and should I add formic acid to get the pd sponge?


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## Lino1406 (May 8, 2021)

To use formic acid or formate salt you'd have the palladium in solution


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## Rem123 (May 9, 2021)

Yes I know that. But when I added sodium hydroxide an brown orange precipitate appeared on the bottom. Is this the palladium that I should process with formic to get the metal sponge?


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## Lino1406 (May 9, 2021)

Maybe, and also other hydroxides


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## Rem123 (May 9, 2021)

And should I process it with formic acid?


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## Lino1406 (May 9, 2021)

Positive, for liquid state. Preferably convert formic acid to sodium formate or ammonium formate, then add a small excess of formic acis


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## Rem123 (May 9, 2021)

Hi. Isn't it better to add the sodium hydroxide to the solution and to precipitate a hydroxide and then add the formic acid by drops untile the hydroxide get a metal?


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## Lino1406 (May 10, 2021)

This shortcut is not logical, 1. By involvement of other elements 2. The accepted treatment with formate salts takes place at near boiling point of both liquid participants


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## Geo (May 11, 2021)

Convert the palladium to an oxide with sodium hydroxide first. I've seen it done with sodium carbonate but I don't understand it that well. Allow the palladium oxide to settle and decant the spent solution. I try to rinse with distilled water. If you have enough time, it best to let it settle and siphon. Add water to cover the salt and heat until the beaker is slightly too hot to touch with your fingers starting out. Add the formic acid in small doses and let it react while stirring. Repeat until you add formic acid and it does not react. The conversion will be complete. It's best to do this in a fume hood or wearing a respirator. Wear gloves and all other appropriate PPE's.


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## Rem123 (May 11, 2021)

Thank you Geo. My second problem is with another palladium AR solution. It color is green. The stannous test is positive for palladium. When I add a drop of DMG/sodium hydroxide solution the color gets red and blue but no precipitate. The red I think is for nickel but why the palladium doesnt precipite. The solution is acidic so the nickel only drops in alkaline solution. When I continue adding DMG the color gets yellowish but still red with no precipite. What should I do?


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## FrugalRefiner (May 11, 2021)

Rem123 said:


> When I add a drop of DMG/sodium hydroxide solution the color gets red and blue but no precipitate. The red I think is for nickel but why the palladium doesnt precipite. The solution is acidic so the nickel only drops in alkaline solution. When I continue adding DMG the color gets yellowish but still red with no precipite.



I am far from an expert on PMGs, but why are you adding a "DMG/sodium hydroxide solution" for testing? I agree the red (or pink) is indicative of nickel, but that's in an ammoniacal or basic solution. For testing purposes, I dissolve as much DMG in distilled water as possible (It's very limited). No un-needed NaOH that could change the pH.

How do you know the solution is acidic? Did you test before or after adding the "DMG/sodium hydroxide solution"?

Might there be enough NaOH in your test solution to push the tested sample to basic?

I'm just guessing in hopes of helping you sort it out.

Dave


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## Geo (May 13, 2021)

The cheap DMG coming out of Russia dissolves better in a solution of sodium hydroxide.


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## FrugalRefiner (May 13, 2021)

All DMG dissolves better in a solution of sodium hydroxide. It depends on your intended use.

For testing, I have never needed to use hydroxide. The amount of DMG that dissolves is tiny, but for testing it works just fine.

If you're using it to precipitate palladium to separate from other metals, then hydroxide will allow you dissolve a lot more DMG in a given volume of solution, keeping the overall volume of solution lower.

My comment, and question, above was specifically regarding testing.

Dave


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## Rem123 (May 23, 2021)

Hi thank you for your comment. I realised that when I make a solution of DMG and sodium hydroxide the solution geta acidic and thats why a red precipitate forms from nickel. Because the pH gets above 7 and the solution is alkali. But you said that I can precipitate palladium with sodium hydroxide and DMG solution but in that case the nickel will precipitate again because it is alkali. Or should I add just a little but sodium hydroxide to dissolve DMG without getting the solution alkali and test the pH?


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## FrugalRefiner (May 23, 2021)

You can use less hydroxide when mixing the DMG, and you can also add some HCl to your solution to maintain an acidic pH.

Dave


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## Rem123 (May 23, 2021)

Ok than you Dave. Another question I will get 60 PC RAM sticks. Could I get 1 gram of gold from them?


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## FrugalRefiner (May 23, 2021)

That's kind of like asking how much a rock weighs. What kind of rock? How big a rock? There is far too much variety to make a guess. I've really never processed much ewaste, so I'm not the one to answer.

Dave


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## Rem123 (May 23, 2021)

Hi. PC DDR RAMs they are like 1kg weight.


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## Geo (May 23, 2021)

1kg of DDR will yield more than 1g of gold. The question would be, can you reclaim what's there or not. It depends on your level of experience.


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## Rem123 (May 23, 2021)

I do first dip the gold fingers in nitric acid for some days. After that I filter the golden foils and dissolve them in AR using minal amound of nitric acid. Later I precipitate with SMB and wash several times with water, and hydrochloric acid and collect the powder. But I am wondering should I precipitate with copperas first and then dissolving again with AR and then precipitating with SMB?


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## Geo (May 24, 2021)

The gold on the fingers is only about 1/3 of the gold in ram sticks. The bulk of the gold is in the IC chips. That was my point. If you can't reclaim the gold from the chips, you will not recover 1g per kg.


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## Rem123 (May 24, 2021)

Yes I know there is gold in IC chips I collect them for another processing. But I have never processed them. I think I should burn them until they get into dust and then process the dust. And does every IC chip has gold in it or not because I opened some and I did not see gold bondings?


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## Geo (May 24, 2021)

Assume all IC chips contains gold. The bond wires can be as small as 1 micron in length and is difficult to see a single bond wire, if at all, with the naked eye. It's only after they have been collected in numbers that you can see the gold.


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## Rem123 (May 25, 2021)

Ok thank you. But can you tell me how is the process about the IC chips?


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## Geo (May 25, 2021)

Incinerate until the chips are white ashed. Mill to a fine dust. This will take more than one milling. Mill once and remove heat spreaders, leads and any large pieces that did not incinerate well. This is done by screening the material. I use 1/4 inch hardware cloth to remove really large pieces. Then I screen using window screen, this is where the copper and steel leads are removed. Anything that will not pass through the window screen is milled again. Then it is screen through #100 mesh sieve. Gravity separate the lighter ash from the metal fines using a small sluice. Collect the heavy fines and leach in nitric acid to remove the copper and silver. The only metal to remain will be gold. Dissolve in aqua regia and filter and drop.


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## Rem123 (May 25, 2021)

Okay thank you my fried. Another question is it better to precipitate gold first with copperas and redissolving and precipitating with smb or only copperas or only smb?


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## kurtak (May 26, 2021)

Backing up a bit to the original question about precipitating & testing for Pd with DMG

Making the DMG testing solution

Dissolve 4 grams of NaOH in 100 ml of hot water then add 5.81 grams of DMG - the 4 grams of NaOH allows for ALL the DMG to dissolve thereby giving you a very effective test solution 

Unless the (acidic) solution to be tested is VERY DILUTE the NaOH will have NO affect on the DMG test for Pd 

Testing the solution; - put 1 ml solution in a test tube - add a couple drops of the test solution - if there is Pd in the solution being tested you "will" get the canary yellow precipitate of DMG Pd

if you get any other color precipitate it is because you used WAY to much NaOH to make your test solution (or you solution is VERY dilute) which is then likely adjusting the Ph up to a point of allowing other metals to precipitate as their hydroxides 

In that case acidifying the (test) solution (to Ph 1) should dissolve all the hydroxides leaving behind only the yellow DMG Pd - if there is/was Pd in the solution to start with

if you don't get the yellow DMG Pd precipitate --- there is NO Pd in the soluton

Kurt


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## Lino1406 (May 26, 2021)

Good to hear from you Kurtak despite shortage of time


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## Rem123 (May 26, 2021)

Thank you Kurtak I will take your advice and try it. Thanks. If you can please answer my previous question for the gold precipitation.


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## Geo (May 27, 2021)

Sorry, I'm not Kurt, but it's best to precipitate from a dirty, mixed metal solution using ferrous sulfate first. Rinse well in boiling water and redissolve. Filter and drop with SMB. This will get you in the high 90's on purity. I usually achieve 99.8% pure using this method.


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## Rem123 (May 27, 2021)

Oh yes thank you and dont be sorry the question was to the all in the forum not specificaly to Kurt. And can anybody tell me should the copperas be chemicaly pure which in white color or it can be comercial for plants which have greenish color. I have seen a sucessful experiments with the comercial one but which is better?


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## Geo (May 28, 2021)

I generally make my own. A couple of ounces of rusty nails in a 1000ml beaker. Add 450ml of tap water. Carefully add 50ml of concentrated sulfuric acid on low heat until the nails dissolves or the reaction stops. Remove from heat and let it cool completely. Filter clear and use. If crystals form, add water until the crystals dissolves and filter and use.


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## Rem123 (May 28, 2021)

Ok thank you.


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## spoke27 (Jun 13, 2021)

kurtak said:


> Backing up a bit to the original question about precipitating & testing for Pd with DMG
> 
> Making the DMG testing solution
> 
> ...


 Dear Kurt Why Hot water ?


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## Charles1975 (Aug 6, 2021)

kurtak I thank u for good advice. Simple easy to understand and priceless Information.


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## Zhazham (Feb 18, 2022)

I'm wondering, if it makes any sense to test with zink? I have greenish solution left of processing gold plated silver. Cemented silver, dropped gold already etc. Solution is very diluted. Added way too much SMB and i was then adding lot of water to get rid of SMB ice. Cold conditions, so i didn't get SMB to react with gold at first.

Now i have this solution and would like to know if it has any palladium or other PGM's. Don't have DMG or stannous at the moment. Solution is going in to stockpot anyway but i'm curious to make a small test with what i currently have, while waiting for better conditions.


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## orvi (Feb 18, 2022)

Zhazham said:


> I'm wondering, if it makes any sense to test with zink? I have greenish solution left of processing gold plated silver. Cemented silver, dropped gold already etc. Solution is very diluted. Added way too much SMB and i was then adding lot of water to get rid of SMB ice. Cold conditions, so i didn't get SMB to react with gold at first.
> 
> Now i have this solution and would like to know if it has any palladium or other PGM's. Don't have DMG or stannous at the moment. Solution is going in to stockpot anyway but i'm curious to make a small test with what i currently have, while waiting for better conditions.


Zinc will precipitate almost all metals in solution. If you cemented silver with copper metal before, all palladium dropped with silver.

Without proper testing, everything is just guessing. Distinguishing black precipitate of palladium from vast ammounts of copper... I will not rely on this approach. 
Make stannous from tin and HCl, it´s easy and bulletproof.


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## Zhazham (Feb 18, 2022)

Ah yes. I didn't think of palladium cementing with silver by using copper. Then better just to add this solution in to stockpot and find something else to do.  Maybe making stannous...or moonshine. Thanks Orvi!


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## Zhazham (Feb 18, 2022)

I just have to add that information is available but thinking and understanding is another thing. Talking of myself..


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## Nadeem (Sep 23, 2022)

Geo said:


> Convert the palladium to an oxide with sodium hydroxide first. I've seen it done with sodium carbonate but I don't understand it that well. Allow the palladium oxide to settle and decant the spent solution. I try to rinse with distilled water. If you have enough time, it best to let it settle and siphon. Add water to cover the salt and heat until the beaker is slightly too hot to touch with your fingers starting out. Add the formic acid in small doses and let it react while stirring. Repeat until you add formic acid and it does not react. The conversion will be complete. It's best to do this in a fume hood or wearing a respirator. Wear gloves and all other appropriate PPE's.


Vry nice i nfo bro thnk u so much


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## Yggdrasil (Sep 23, 2022)

Nadeem said:


> Vry nice i nfo bro thnk u so much


Do not use lingo please. People who use translators may struggle to get the meaning.


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