# Catalytic converter recovery and refine



## dmarth10 (Aug 11, 2008)

hello all
I'm a newbie with refining. I have been reading so much info on the AR process for cats. It seems that all I can find is 4 parts hcl and 1 part nitric for making AR. That's the only info I can find. I don't no if roasting is necessary. If so how do I do that. Then what is next. Just drop the honeycomb or pellets in? So next the pt pd and rh are suspended in the AR? Then I would like to actually separate the pt pd and rh from eachother to make them pure. I cannot find out how to precipitate then all separate from one another. Basically I read for a couple months and found nothing. I really need a step by step process breakdown. I don't know where to find this. Please can someone point me in the right direction? Mainly the separation of the pgms from Eachother. I appreciate all your help. 

Thanks again
Dave

P.s. Sorry for typos as I just spent a half hour typing on my phone.


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## lazersteve (Aug 11, 2008)

Dave,

Welcome to the forum.

Once you have extracted the PGMs from the cats the metals will all be dissolved in the liquid.

Filter the solution until it is completely transparent with no floating particles or sediment.

Adjust the pH of the solution to around 5 using soda ash. 

Add finely powdered zinc dust (-200 mesh). The solution will fizz and foam as the metal is added so add slowly with lots of stirring. Continue to add the zinc until the color of the solution turns clear with a gray suspension in it. Most of the black/gray powder should settle quickly. If the solution is still colored red, orange, or yellow, more zinc is required. If zinc additions do not produce a reaction then add a few mL of HCl. If you see a white layer mixed with the black powder on the bottom add water and stir.

Once the zinc additions are finished, filter the solution through fine filter paper preferably in a vacuum set up. Rinse the black sludge in the filter with water several times.

Transfer the sludge to a beaker and add four parts HCl and one part nitric acid. Boil the reaction until no more of the black powder dissolves. A second fresh dose of AR should be used to confirm everything is dissolved. Combined the two solutions. This will dissolve the Pd and Pt and leave the Rh behind as a fine gray powder.

Filter the gray powder (Rh) out of the solution, washing several times with water. 

DeNox the solution as usual to convert the nitrates to chlorides and to remove any left over nitric acid. 

Evaporate the solution down until syrup like.

Add a saturated solution of ammonium chloride and water to the hot concentrated Pt and Pd solution. The Pt will precipitate as a yellow to orange colored salt. Vacuum filter off the liquid and add more ammonium chloride to be sure all the Pt is precipitated. 

Add sodium chlorate to the hot liquid to precipitate the Pd as a red salt. When no more red powder forms with chlorate or ammonium chloride additions, filter off the red powder and add the left over solution to your stock pot. 

Incinerate the salts in separate fused quartz or alumina dishes.

Melt the incinerated metals with a hydrogen torch.

Steve


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## dmarth10 (Aug 12, 2008)

Hello,
Thanks for the very detailed reply. I appreciate your time. However, I still do have some questions for you. I am still not sure weather or not I need to roast the honeycomb, or crush, or both. You also said that when I take the black sludge and put it in AR again, and make a second AR, dissolve the rest, then combine the two, that will precipitate the Rh? Is there something I need to add to precipitate Rh? Or will it just do it. You then said DeNox the solution. Im not familiar with that term. Could you please ellaborate. Next, you said "Add a saturated solution of ammonium chloride and water to the hot concentrated Pt and Pd solution." What proportions do I make the ammonium chloride solution and do I need to heat up the Pt and Pd sludge? If so, how hot and long do I heat for. Would I be using a hot plate or bunsen burner to evaporate? Then, once I make that sollution, do I just pour in the Pt/Pd sludge, then it starts to precipitate? Next, you say Add sodium chlorate to the hot liquid to precipitate the Pd as a red salt. Do I need to mix nacl with water or anything else? Next you say insinerate the salts. Are all three, Pt Pd and Rh going to be salts? How do you suggest insinerating them. Last, you say use a hydrogen torch to melt the metals. I have an oxy acetalene torch. Is that hot enough? Or is that too hot. 

I understand I have a ton of questions, but I would be more than grateful for a reply of some sort. Not necessarily a direct answer if you dont have time, it could even be directing me to where I can find the answers to my questions.

Thank you for reading.

David


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## lazersteve (Aug 16, 2008)

dmarth10 said:


> I am still not sure weather or not I need to roast the honeycomb, or crush, or both.



It all depends on the method you choose to use to extract the PGMs. Roasting isn't necessary, but recommended by some. I don't roast mine.



dmarth10 said:


> You also said that when I take the black sludge and put it in AR again, and make a second AR, dissolve the rest, then combine the two, that will precipitate the Rh? Is there something I need to add to precipitate Rh? Or will it just do it.


The Rh is what remains when the Pt and Pd dissolve in the AR treatments. Just filter the solution and the majority of the Rh will remain in the filter.



dmarth10 said:


> You then said DeNox the solution. Im not familiar with that term. Could you please ellaborate.


DeNox= to remove nitric oxides (NO and NO2 = NOx) and excess nitirc acid. Boil down the solution to a syrup and add HCl. Repeat until no more red fumes are produced.



dmarth10 said:


> Next, you said "Add a saturated solution of ammonium chloride and water to the hot concentrated Pt and Pd solution."


Saturated ammonium chloride= add ammonium chloride to boiling water until no more will dissolve.



dmarth10 said:


> What proportions do I make the ammonium chloride solution and do I need to heat up the Pt and Pd sludge? If so, how hot and long do I heat for.



(NH4)2PtCl6 = Diammonium hexachloroplatinate, 

NH4Cl=53.49 g/Mole x 2 = 106.998 g ; Pt =195.084 g/ Mole

195.084 g /106.998g = 1.82 grams Pt per gram of NH4Cl,

so use 1 gram of saturated ammonium chloride solution for each 2 grams of dissolved Platinum. The filtered, hot Pt and Pd solution should contain no sludge when the saturated ammonium chloride solution is added. Heat to just below boiling. When hot add the hot saturated ammonium chloride solution.



dmarth10 said:


> Would I be using a hot plate or bunsen burner to evaporate?



Sure if you want to.



dmarth10 said:


> Then, once I make that sollution, do I just pour in the Pt/Pd sludge, then it starts to precipitate?


Add the hot ammonium chloride solution to the filtered, hot Pt and Pd solution. No sludge is involved. The Pt will precipitate as a orange to yellow salt, Diammonium hexachloroplatinate. Filter out this colored salt.



dmarth10 said:


> Next, you say Add sodium chlorate to the hot liquid to precipitate the Pd as a red salt. Do I need to mix nacl with water or anything else?


 No, add dry sodium chlorate (not sodium chloride= NaCl) a small crystal at a time to the Pd solution



dmarth10 said:


> Next you say insinerate the salts. Are all three, Pt Pd and Rh going to be salts? How do you suggest insinerating them.



If you followed my previous post, you should realize each salt gets filtered out as you proceed. This separates the Pt from the Pd, the Rh metal stayed behind when the AR was originally filtered. I heat mine slowly in a fused quartz dish. Hoke explains all this in detail.



dmarth10 said:


> Last, you say use a hydrogen torch to melt the metals. I have an oxy acetalene torch. Is that hot enough? Or is that too hot.



Temperature is not the only concern, loss of product (Pt and Pd ) due to the carbon in the Acetylene gas is also possible. Carbon forms volatile compounds with Pt and Pd.



dmarth10 said:


> I understand I have a ton of questions, but I would be more than grateful for a reply of some sort. Not necessarily a direct answer if you dont have time, it could even be directing me to where I can find the answers to my questions.
> 
> Thank you for reading.
> 
> David



David all this could have been answered by using the forum search function, and/or by reading Hokes book which is a free download here.

Steve


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## dmarth10 (Aug 30, 2008)

Hello folks,
I have found a "way" to make homemade nitric on the forum. I found that hcl and sodium nitrate will make the nitric. Is this going to work to make AR? I am wondering if it would be just as well as regular nitric. I want the AR for catalytic converters. The reason I am interested in making it is because I can not find a good supply of nitric for a lower price. The best pricing I have found is 6 2.5 liter bottles for 3?.?? per bottle. Is there other sources for cheaper that you guys found?

David


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## lazersteve (Aug 30, 2008)

David,

HCl + NaNO3 makes poor man's AR, technically not nitric, but nitric is formed in situ.

If you want lab grade nitric distill NaNO3 and concentrated H2SO4.

Steve


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## dmarth10 (Sep 2, 2008)

With the prices of converters on eBay, does that leave any room for profit if refining converters by myself?


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## dmarth10 (Sep 8, 2008)

Thanks for your help so far. I was wondering a time frame for the recovery of pgms in honeycomb in AR. Can anyone recomend a min and max recovery time untill its all extracted?


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## cloomis (Sep 9, 2008)

wow ,steve i didnt understand this your answer aww just kiddin great answer


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## dmarth10 (Sep 28, 2008)

Hey Steve,
With the honeycombs in AR, are there typically 90-95% pgms recovered with the steps you stated? Thats what I have been reading. Then if you re-refine, you will get about 99%.


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## Palladium (Oct 11, 2009)

:mrgreen:


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## Anonymous (Oct 12, 2009)

One thing I always wanted to ask but just now remembered. If the Rh is left behind in the secound dissolve in AR why was it dissolved in the first run?

thanks
jim


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## lazersteve (Oct 12, 2009)

Jim,

With used catalytics the Rh gets oxidized. This allows it to dissolve.

Steve


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## Anonymous (Oct 12, 2009)

Thanks,
I knew there was something but wandered what it was.

Jim


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## plamenppp (Mar 6, 2010)

lazersteve said:


> Dave,
> 
> Welcome to the forum.
> 
> ...



I could not understand what is the liquid. Is it AR? If yes, will it dissolve Rh (oxidised Rh)?
And something else - "with used cats". What does it mean? Is it possible that some of the Rh will not be oxidised? If yes, how will it be dissolved?


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## lazersteve (Mar 6, 2010)

Plamen,

The liquid is the solvent that you used to extract the PGMs from the cats (e.g.: AR, HCl-Cl, etc.).

Used cats are ones that have been used in an automobile and have been exposed to high temperatures from the engine and exhaust fumes. This works to form oxides in the cat which allows the Rh to dissolve.

Steve


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## plamenppp (Mar 6, 2010)

lazersteve said:


> Plamen,
> 
> The liquid is the solvent that you used to extract the PGMs from the cats (e.g.: AR, HCl-Cl, etc.).
> 
> ...




It is good when there is someone to keep an eye on you. Thank you Steve! I have no patience for the DVD to arrive.


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## Anonymous (Mar 15, 2010)

Reading on how the soot and carbon from auto cats is causing problems for processing auto cats, sounds like Piranha would do the trick of removing carbon based soot.

http://en.wikipedia.org/wiki/Piranha_solution

http://www.enma.umd.edu/LAMP/Sop/Piranha_SOP.htm


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## Buzz (Mar 15, 2010)

Crikey, That sounds dangerous! :shock: 

Who wants to go first!!

Buzz


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## qst42know (Mar 15, 2010)

lazersteve said:


> Plamen,
> 
> The liquid is the solvent that you used to extract the PGMs from the cats (e.g.: AR, HCl-Cl, etc.).
> 
> ...




As a point of curiosity after twice leaching the cats to remove Pt and Pd which may be volatile in the presence of so much carbon. Is there enough Rh remaining to justify roasting to oxidize more?

Or is this just tail chasing?


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## samuel-a (Mar 15, 2010)

if a cat is containing Rh, i belive the right way is to roast before the first leach..


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## markqf1 (Mar 15, 2010)

Roasting or, not roasting, is an ongoing debate.
I've found that it is possible to get 90+ percent of the pt and pd without roasting.
The rh is a different animal.
It usually requires a second, or even a third step, to extract the rh that hasn't been converted to oxides.
Bisulfate fusion works good for this.

Mark


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## Palladium (Mar 16, 2010)

I've wondered for some time if you could use ozone and water to do a preleach instead of roasting. Ozone reacts with carbon to form carbon dioxide, even at room temperature.


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## markqf1 (Mar 19, 2010)

Ralph,
I can't tell you the answer to that question.
Maybe some of our more educated members will reply.
I can tell you that pre-roasting, compared to not roasting, has produced a substantial increase in rh recovery on the first run, for me.

Mark


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## qst42know (Mar 19, 2010)

markqf1 said:


> Ralph,
> I can't tell you the answer to that question.
> Maybe some of our more educated members will reply.
> I can tell you that pre-roasting, compared to not roasting, has produced a substantial increase in rh recovery on the first run, for me.
> ...



Are you losing platinum and palladium in doing so?


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