# Black powder refining spoon feeding request



## panache (Sep 29, 2015)

Hi all,
First time poster, long time lurker (actually thats a lie i joined a few weeks back.)

i purchased a groundwater remediation machine that had been dropped off a forklift (literally, not a euphemism), after consuming $30 worth of grinder blades i ended up with 70kg of 'cat ox', a sud chemie product i have the msds for (<1% Pt, <1%pd, <1% propriety metal oxide, <1% propriety promoter, remainder al2o3).
After scrapping the 300kg of stainless (0.70c/kg, so sad all 314 as well) i began reading.

Many papers later, chanced upon a sth korean gem
recovery of platinum and palladium from spent petroleum catalysts by a hydromettalurgical method, panpan sun, manseung lee, (kor. J. Met. Mater), Vol 51, No 12, pp873-881

The authors (aside from being descendants of gold panners), (because his name is PanPan), focused on finding a method for recovery of the pt/pd without dissolving the alumina,......

Anyway, did about 15ish 50g trials, figured upon a method, scaled up to 1kg, ppt out the 'black powder' using Al chunks (43g), took this to gold buyer for free xrf

Black powder has pt 35.9%, pd 12.5%, fe 7.6%, Cu 28.1%, Pb 2.0%, Rh 3.6%, Zn 3.8%

So i treated another 7.5kg of catalyst, obtained a further 400g of 'black powder, i am going to assume its assay is similar.

As an organic chemist i am finding this first foray into pgms pretty relaxing, i mean unless you pour the stuff down the sink you cant destroy an element (although i have read of volatisation losses). That said, the volume of your solutions (20 liter drums labeled 'may contained pt', 'may contain pd', 'probably doesn't contain much but just in case keep') can build up very quickly. I can just see myself dragging those suckers through two house moves and procrastinating doing anything with them.

Now for the spoon feeding request. I have done some evenings of reading, but know how can be better by far, and i have none.

To purify the above 'black powder' i intend the following, but would gladly welcome any advice

Cover the powder in 20% HCl and digest @50C for an hr with stirring, i believe this will dissolve the fe, cu, pb (pbcl2 being soluble in strong Hcl solns) and Zn, filter, wash twice with boiling water, dry weigh (this is my check to ensure the correctish amount of mass has been lost).

The pt/pd/rd ppt is then dissolved in a minimum of hot A.R. (5pt hcl, 1 pt Hno3, 1 pt water??, it appears AR is different in every lab, advice?)

Evaporated on a steam bath, HCl added, thrice repeated.

Add Nh4Cl solution (what concnetration of Nh4Cl soln is best here?) until no more orangy ppt appears upon further addition, chill to 10C, filter, wash filtrate thrice (with cold clean Nh4Cl solution), dry orange powder, heat slowly in an evaporating basin to 370C (in the dining room whilst mother in law is eating), then more rapidly to 900C, testing the fumes for colour (white good, yellow, other colours bad, Pt volatilisation).

What remains should be Pt sponge, about 130g.

From above separated orangy ppt solution is passsed a slow stream of cl2 gas until no more ppt forms or the gas ceases to be adsorbed in any way. Solution chilled overnight, yellow ppt filtered washed (Nh4Cl soln again i assume), dried and heated gently as with orangy ppt above. 

What remains should be about 60g of palladium sponge

The filtrate and all Nh4Cl washings from above are evaporated to dryness in an excess of Hcl, then treated with ethanol, producing some double salt of Rh/NaCl, a red powder. This powder is dried and then heated (temp here?) in a glass tube with a stream of H2, the resultant Rh metal and Nacl is washed clear of the Nacl and dried.

Comments anyone?


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## Palladium (Sep 29, 2015)

I can't help you with the refining aspect of the pgm's, but maybe with the separation for refining. If you use nitric to wash it it should take everything except the pt and rh leaving them as a residue. You can then use copper to cement the pd from the nitric wash which should be a pretty clean separation giving you a good high grade materiel for refining. After you wash the residues real good you should have a high grade material left over for refining the rh and pt.


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## FrugalRefiner (Sep 29, 2015)

panache, welcome to the forum. I see some things in your post that indicate you've done some research. I see others that indicate you need to do more.

I hate to be negative, but if you're truly an organic chemist, you need to do some review on how to write chemical formulas. al2o3, fe, cu, pb (pbcl2, hcl, 1 pt Hno3? See Chemical Formulas in the Tips for Navigating and Posting on the Forum thread. If you're a chemist, please take the time to write your formulas correctly so others won't be further confused by such errors.

XRF results are notoriously unreliable. Don't rely on them too much.

For treating your waste solutions, take a look at the Dealing with Waste thread in the Library section of the forum.

As for dealing with the black powder, your proposed process has some problems. HCl alone probably won't dissolve much copper. You will struggle to dissolve the "pt/pd/rd" in AR (I'm assuming you meant rhodium (chemical symbol is Rh, not Rd)) Rhodium is very difficult to dissolve. "dry orange powder, heat slowly in an evaporating basin to 370C (in the dining room whilst mother in law is eating)". If this is supposed to be a joke, it's NOT funny. We do not joke about what we do. Someone else who reads your post may not realize it was supposed to be a joke and think that the advice of an organic chemist should surely be sound. If it's not a joke, NEVER process in your dwelling! I don't understand your logic for producing palladium. Ethanol and precious metals don't play nice together. 

Again, I welcome you to the forum, but put your chemicals away and start doing some serious research.

Dave

Edit to add, you really need to understand the dangers involved in dealing with the platinum salts. They are very toxic.


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## panache (Sep 30, 2015)

Dave,
Thank-you for your even tempered and sensible reply. You are quite correct and i was unconscionably flippant. 

As for writing the formulas correctly i was simply lazy, i won't be so again.

Are the xrf results notoriously unreliable because of the sampling method used or because the technique is unreliable? I had spice milled my black powder thoroughly then sample it thrice. When i got there i asked for all three to be run, the numbers gave a confidence window of a few percent on the Pt, Pd and Cu.

So for dissolving the ~80g Cu in the sample, what would you suggest, should i simply digest it with more HCl(aq), at reflux, and for longer?

Thank-you for the advice upon the dangers of the Platinum salts.

'The separation i quoted was from Stotts Standard Methods of Chemical Analysis, 5th edition, a very useful tomb as it just predates the instrumentation era that put most procedures out of the scope of the shed. This was the specific method used for mixtures of Platinum, Palladium and Rhodium.

Cheers mark


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## Lou (Sep 30, 2015)

XRF results are always inflated on powders. 

Thankfully you're an organic chemist so this should be slightly easier:

When you have your cemented product...
1. Dissolve everything in HCl/Cl2 gas. You can "pulp out" the base metals with HCl as you'd thought but some PGM may dissolve. Precipitate the lead with sulfuric acid. Filter.
2. To the clarified likely dark brown solution from *1*, boil it for 30 min to decompose Pd(IV)-->Pd(II) then precipitate the Pt with saturated potassium chloride solution to get K2PtCl6. Add in a 1.5 X molar excess. You may also use acetamide and hydrolyze it for a higher purity precipitate of (NH4)2PtCl6. Rinse the potassium salt precipitate with 2 M KCl that is 3-4% w/v HCl until the filtrate is colorless; use ammonium chloride in the same fashion if you go the other route. 
3. To that solution from *2* whence K2PtCl6 was obtained, add in more KCl solution and introduce sodium chlorate, chlorine, hypochlorite, etc. The result is K2PdCl6, rinse as you would for the Pt salt.
4. To the filtrate from *3*, add in zinc to get any metal traces and roll them over into the next batch.

This is the recovery aspect. The refining aspect I cannot share.

Lou


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## panache (Oct 1, 2015)

Lou,
Thankyou for that. Few questions, i will keep them to yes/no questions to make it simple to reply(if the answer is yes).
I am assuming that 'dissolve everything in HCl/Cl2 gas' is equivalent to the technique of adding H202 to your solution of HCL (generating the Cl2 gas insitu)?

By 'pulping out', are you referring to the HCl digestion i suggested in my initial post?

Precipitating the Pd with sulphuric, do you need much of an excess of sulphate to ensure all the lead goes or is it best to it to a minimum?
I assume fast stirring slow addition of say 20% sulphuric to keep the ppt size small and reduce inclusions?

Lastly does the xrf inflate the components in lower proportions or those in higher proportions in the sample, i would assume the low.

Thanks again
mark


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## panache (Oct 16, 2015)

so i processed a further 7.5kg of the catalyst material and ended up with around 400g of black powder with a xrf spectrum as listed earlier in the thread.
Then i ran into a wall.
The black powder was dried then brought to red heat, ground in a spice mill and finally an attempt was made to dissolute it into hcl/cl2 (via Hcl(aq)/h2o2). these were the conditions that leached the PM's from the alumina support intially.
The problem is that the black powder is impervious to these conditions. i have tried multiple runs, h202 concentrations, temperatures. I then tried simple AR at 80C, none of these conditions dent the powder.
Does anyone have any further tips or tricks for me to try on the black powder to get it to dissolve. 
Thanking you all in advance for your replies, any advice would be welcome as i am tearing my hair out
Mark.


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## Grelko (Oct 16, 2015)

panache said:


> i purchased a groundwater remediation machine that had been dropped off a forklift (literally, not a euphemism), after consuming $30 worth of grinder blades i ended up with 70kg of 'cat ox', a sud chemie product i have the msds for (<1% Pt, <1%pd, <1% propriety metal oxide, <1% propriety promoter, remainder al2o3).
> After scrapping the 300kg of stainless (0.70c/kg, so sad all 314 as well) i began reading.
> 
> Black powder has pt 35.9%, pd 12.5%, fe 7.6%, Cu 28.1%, Pb 2.0%, Rh 3.6%, Zn 3.8%



Am I reading this right? You ground up a water remediation machine? By the chance that this is a yes, ask the people you bought it from, which chemicals or materials were in the water, and what they added to the water, before they purified it. The machine would have small buildups of chemicals, dirt etc, in it still. Maybe it's a certain type of organic material that's coating the black powder, which isn't letting it dissolve? 

For example, Wikipedia and other sites - "Stink bug" smell is produced by certain chemicals that can include, aldehydes, cyanide, trans-2-decenal and trans-2-Octenal, or others. 

Also, what else could be in it? These numbers only add up to 93.5%.

Edit - Since you dried it to red, that should have taken care of the organic materials. Maybe melting into cornflakes, then re-dissolving?


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## samuel-a (Oct 19, 2015)

panache said:


> so i processed a further 7.5kg of the catalyst material and ended up with around 400g of black powder with a xrf spectrum as listed earlier in the thread.
> Then i ran into a wall.
> The black powder was dried then brought to red heat, ground in a spice mill and finally an attempt was made to dissolute it into hcl/cl2 (via Hcl(aq)/h2o2). these were the conditions that leached the PM's from the alumina support intially.
> The problem is that the black powder is impervious to these conditions. i have tried multiple runs, h202 concentrations, temperatures. I then tried simple AR at 80C, none of these conditions dent the powder.
> ...




Hello Mark, welcome to the forum.

It is quite strage result.
Perhaps you would want to avoid calcining the mixed metals powder as it forms oxides which may prevent attack by the acid.
Alternativly (or in conjunction) another theory would be - assuming you calcined the mixed metals at appprx. 500-600 C some sintering has occurred, thus preventing acid attack.
Either way, i would suggest not heating this mixed metlas powder and choose one of the offered procedures above.


In a money making perspective, i would probably not go any further than the cementing process - at this point i would have taken a representative sample, have it assayed properly and then send few sample for assay and pricing at a pro refiner like Lou or any number of PGM's refiners out there.


p.s. - though there's alot of 'ifs' and 'buts'... the numbers doesn't add up...
Say 7.5 Kg of starting material would contain no more than 75g Pt and 75g Pd, lets assume you have dissolved and cemented 100% of the potential PGM's, your assay of the cemented mixed metals powders should say 18.75% (top) Pt and same for Pd.


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## panache (Oct 21, 2015)

Thanks for your reply Sam,
I will try dissolving some non calcined/sintered black powder immediately.

As for the numbers, it appears that despite whats on the msds, there appears to be three times more platinum than palladium on the catalyst.
I will fill all on the details once i am done.
As for the refining, yes i have decided against doing it myself, apart from this small trial now to satisfy my curiosity.

As for the sintered/calcinced/oxidised black powder, i guess ill try the NaCl/Cl2(gas) at dull red heat method, i can probably get away with doing it in borosilicate glass, and it looks interesting!! 
However not for a few weeks


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## panache (Oct 22, 2015)

Lou said:


> ....2. To the clarified likely dark brown solution from *1*, boil it for 30 min to decompose Pd(IV)-->Pd(II) then precipitate the Pt with saturated potassium chloride solution to get K2PtCl6.
> 
> Lou




Lou, it was probably just a simple error, however in case its not and i'm missing something, wouldn't the decomposition be the other way around (Pt(II)-->Pt(IV), as the Pt(IV) oxidation state is the more stable of the two and also you need this oxidation state to form the hexachloro complex?

Cheers Mark


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## Platdigger (Oct 23, 2015)

You could try smelting these powders. Perhaps to silver (or lead).
Then pour shot, and proceed from there.


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## Lou (Oct 23, 2015)

Panache,

You are missing something.

I'm talking Pd not Pt. Pd(IV) is unstable kinetically and will revert to Pd(II) + Cl2 when boiled. 

You can of course just precipitate concomitantly the Pd(IV) and Pt(IV), then boil or otherwise recrystallize (that goes to secret sauce land, can't say) the K2PtCl6 from K2PdCl4 in hot water.

I suggest you pick up some weak base resin 

Cheers.


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## thomasbrock (Nov 1, 2015)

Take ur mixed oxides and hit themwith oxy hydrogen in fused quartz crucible.I think when u calcine platinum and palladium ammonium chloride salts they form oxides anyway.And from what I've seen thats what u wind up smelting with oxy hydrogen.You might compact ur oxides so they dont blow away.


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## martyn111 (Nov 2, 2015)

thomasbrock said:


> Take ur mixed oxides and hit themwith oxy hydrogen in fused quartz crucible.I think when u calcine platinum and palladium ammonium chloride salts they form oxides anyway.And from what I've seen thats what u wind up smelting with oxy hydrogen.You might compact ur oxides so they dont blow away.



Please refrain from using texting lingo on the forum, as Harold would tell you, if you mean 'you' write you not 'u'


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