# Catalytic converter pgm recovery and refining



## Leesmithyt33 (Jun 3, 2022)

Hey everyone in relatively new here I've been having a snoop for a few weeks but this is my first post. 
I have managed to get my hands on about 35 catalytic converters brand new and about 20 years old(been in storage along time), unfortunately I'm not 100% sure what jeep/truck they've come off as they have no metal case over the cat (i do know for a fact they're not car cats) . 

So my thoughts.. They're basically useless to me as they are (I can't sell them to any scrap yard without serial numbers) so I've decided to recover the metals myself, this is my first time recovering pgm metals. 

I am well aware of the dangers involved in this and rest assured I am taking every precaution possible to ensure mine and everyone else safety. 

I have already started the process and I would like to log my progress of what I get back and how it goes on here, and maybe someone else here has some tips for me? 

So I broke up 11 cats into a bucket (some fine bits but mostly the size of computer mouse) added 5L HCL and 5L of water I then added sodium hypochlorite and sodium chlorate every other day ( mixing regularly) for about a month. 

This project took the back burner for 3 months or so then so the cats were sat In the aqua regia all that time, I have now processed all the red solution and precipitated the black particulates out with zinc, i was surprised how much zinic I actually used during this process. 

The black pgm particulates I have fell out of solution fast and settled quick, I am now at the stage where I have started to clean the black powder with HCL and warm water so I can get a weight measurement when it is dry. 

I have no doubt I have lost some pgm metals over the the course of extracting it so far so any tips would be much appreciated thanks for reading! 

(picture attached is the black powder and HCL wash I'm assuming the green layer is zinc in solution)


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## Lino1406 (Jun 5, 2022)

Check the green layer with stannous chloride, it may contain palladium


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## orvi (Jun 5, 2022)

Whenever you see coloured solution when refining/recovering PGMs, test it with SnCl2. Palladium is somewhat soluble in oxygenated HCL or with presence of Cu traces - if finely divided. So be aware of this fact.

Sreetips has a great video on processing cat material. Unfortunately, with leaching technique, some values can be trapped in the matrix of honeycomb. Full recovery can only assure smelting of the cat powder with good flux at high temperature. Usually there is no point in crushing the cat comb, but placing it whole into the bucket that way, leach can freely flow through the combs and strip them out of PGMs.


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## JayJayJay (Jun 7, 2022)

Hi. 
First attempt at refining cat converters.
After being intrigued when I advertised my car for wrecking and having many people call me asking " how much for your car converter" I decided to have a go at seeing what I could get from it myself.
I used HCL and chlorine to leech it .
I have filtered the pregnant solution and used zinc to precipitate.
I wasn't sure if the thick dregs were of any value ( they seemed very sparkly gold and silver) so I leeches them again.
This time when I filtered I got a very yellow solution. Could it be Gold?
The dregs still have quite a lot a black sludge. There are conversations where they say gold can appear like this?
Some pictures attached.
Any suggestions on how to maximise the extraction of all metals.
Cheers.......


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## eaglekeeper (Jun 8, 2022)

JayJayJay said:


> I have filtered the pregnant solution and used zinc to precipitate.
> I wasn't sure if the thick dregs were of any value ( they seemed very sparkly gold and silver) so I leeches them again.


Are you only using coffee filters to filter with?, If so I find they are not very good with the fine stuff. Not even running it through multi times it's always little cloudy. I use a coffee filter to get out the big stuff first and then use a Qualitative, Slow flow filter with gravity filtration....and by slow, I mean it takes all day....but it's crystal clear the first time. Second drawback with slow flow filters, vacuum filtration isn't really an option because I have always sucked holes in the filter paper,, every time. 

Those sparkly bits* could possible* be part of the insulating fabric that separates the beds from the outer case. Those sparkly bits in the insulation (probably mica of sorts) can sometimes pass through coffee filters.

Update.... now that I looked close at pic 1661 and 1339......that does look like the sparkly mica stuff. It has *no* value.

That yellow solution is probably dilute Pt, never heard of gold in Cat's.......Stannous test will answer that for sure.

In my opinion, Unless you plan on smelting..... Never grind/crush you Cat's.....Multiple large pieces are okay. Handling these powders are a pain in the butt, not to mention the inhalation hazards.


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## JayJayJay (Jun 8, 2022)

Thanks for the tips.
I'm using filter paper from a lab supply place.
I put the converters in whole.
I removed all the fabric insulation ( well I thought I did)
The only things I put in the leech solution was the "honecombe" style ceramic parts. 
Will look at coffee filter for initial filter.
It takes all day to filter with the lab filter paper. 

Here is a pic of what's left after fine filtration. 
Still a slightly purple liquid.


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## Leesmithyt33 (Jun 9, 2022)

Lino1406 said:


> Check the green layer with stannous chloride, it may contain palladium





orvi said:


> Whenever you see coloured solution when refining/recovering PGMs, test it with SnCl2. Palladium is somewhat soluble in oxygenated HCL or with presence of Cu traces - if finely divided. So be aware of this fact.
> 
> Sreetips has a great video on processing cat material. Unfortunately, with leaching technique, some values can be trapped in the matrix of honeycomb. Full recovery can only assure smelting of the cat powder with good flux at high temperature. Usually there is no point in crushing the cat comb, but placing it whole into the bucket that way, leach can freely flow through the combs and strip them out of PGMs.



Thank you guys, I have the green solution separate to refine at a later date I have tested and it does in fact have some pgm in it and at the bottom of my stock pot is black pgm precipitate. 

I have watched sreetips videos and they are very informative, yea I have no doubt that I could probably soak the cats again and get more back I may do it again at a later date. 

I have washed, dried and weighed up my black pgm precipitate and I had 22gs here I probably have alot more in my stock pot that I have to refine. 

There was an accident today, I dropped my glass full of my black pgm precipitate on the floor, Atleast half of it came out onto the carpet and as it was a fine dust has embedded its self into said carpet. 

I cut up the carpet added it to hcl and sodium chlorate and some bleach to try and save as much as possible, after filtering many times and precipitating the black pgm back out I have now added it to hcl and hydrogen peroxide filtered it again but as I have too much solution now (about 1L aiming for 440ml of hcl+pgm+h2O2) I'm precipitating it back out with zinc so I can concentrate it down to 440ml. 

Mistakes happen sometimes but everything is cleaned up and fine now, goes without saying I have probably lost a little will keep this updated as I go along.


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## orvi (Jun 9, 2022)

Leesmithyt33 said:


> Thank you guys, I have the green solution separate to refine at a later date I have tested and it does in fact have some pgm in it and at the bottom of my stock pot is black pgm precipitate.
> 
> I have watched sreetips videos and they are very informative, yea I have no doubt that I could probably soak the cats again and get more back I may do it again at a later date.
> 
> ...


Get the recovery right before you move on to the refining (if you intend to refine). Refining is a LOT more complicated than just leaching and zinc-ing PGMs out.

Accidents happen. We all know. If it was in form of PGM powder, my choice would be probably to incinerate it to recover values. But in form of cement, PGMs are relatively easily soluble in AR (cement Rh is more problematic, but mix from cat will dissapear quickly). So leaching it out, rinsing and cementing again would be OK. However, I would be concerned what will form from the plastic carpet in these conditions. It could be fine, or it could disintegrate to some oily viscous goo (happened to me numerous times when dealing with plastic in AR).


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## JayJayJay (Jun 9, 2022)

Is there a good way to check if your HCl h2o2 dissolving solution is saturated? Does this occur?
Can you expect non pgm sediment?
Colour of solution.
Colour of sediment?


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## Leesmithyt33 (Jun 10, 2022)

orvi said:


> Get the recovery right before you move on to the refining (if you intend to refine). Refining is a LOT more complicated than just leaching and zinc-ing PGMs out.
> 
> Accidents happen. We all know. If it was in form of PGM powder, my choice would be probably to incinerate it to recover values. But in form of cement, PGMs are relatively easily soluble in AR (cement Rh is more problematic, but mix from cat will dissapear quickly). So leaching it out, rinsing and cementing again would be OK. However, I would be concerned what will form from the plastic carpet in these conditions. It could be fine, or it could disintegrate to some oily viscous goo (happened to me numerous times when dealing with plastic in AR).


I meant recovery of my stock pot not refine my bad, but I will be refining eventually I've gone over it a few times so I'm pretty confident in my ability to tackle it. 

It might not be perfect but I will try, I only need about £1000 back from all of the cats to break even for the chemicals, beakers etc.. I'll be happy with anything over that as this is honestly quite fun.

Would be nice to earn a good bit off it but if I only BE then I won't be too bummed out. 

I found that I did have something floating in my solution after I took the carpet out but luckily enough I've managed to either filter it off or wash it out, I do still have like a white precipitate mixed in with my black pgm but I'm hoping when I mix it with hcl+ h2o2 and filter it that will disappear.


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## eaglekeeper (Jun 10, 2022)

Question for those over in the EU.... How often does the Cat's there contain Pd?... I have done lots of Cat's here from domestic cars/trucks and to this day I have never found a Cat that tested for Pd.


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## orvi (Jun 11, 2022)

Leesmithyt33 said:


> I meant recovery of my stock pot not refine my bad, but I will be refining eventually I've gone over it a few times so I'm pretty confident in my ability to tackle it.
> 
> It might not be perfect but I will try, I only need about £1000 back from all of the cats to break even for the chemicals, beakers etc.. I'll be happy with anything over that as this is honestly quite fun.
> 
> ...


Be careful when adding H2O2 to PGMs in HCL. They catalyse decomposition of the peroxide quite violently, and mixture can easily foam over.


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## Yggdrasil (Jun 11, 2022)

orvi said:


> Be careful when adding H2O2 to PGMs in HCL. They catalyse decomposition of the peroxide quite violently, and mixture can easily foam over.


If one have concentrated Peroxide, this could happen.
But usually when dissolving in HCl and Peroxide, one use plenty of HCl and then add 10-30% Peroxide the same way you use Nitric. Small additions.
In these cases catalytic decomposition should not be an issue.


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## Leesmithyt33 (Jun 11, 2022)

orvi said:


> Be careful when adding H2O2 to PGMs in HCL. They catalyse decomposition of the peroxide quite violently, and mixture can easily foam over.


I made sure to drip feed the H2O2 into the HCL for that reason i added about 2-3ml at a time, it did get very warm and did foam a little but was fine.


Yggdrasil said:


> If one have concentrated Peroxide, this could happen.
> But usually when dissolving in HCl and Peroxide, one use plenty of HCl and then add 10-30% Peroxide the same way you use Nitric. Small additions.
> In these cases catalytic decomposition should not be an issue.


I'm using 36% HCL and 12% H2O2 i did see a small reaction but was limited because i drip fed it in.

Thank you guys!
sreetips videos has helped enormously in the safety department.

edit;12% H2O2 not 14%


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## orvi (Jun 11, 2022)

Solutions of H2PtCl6 can become very, very concentrated. You can easily go past 600g/L. We once had a solution of 500g in 500 mL - very heavy  but these can become impractical. With Pd and Rh, I do not have much experience on how concentrated you can go... But I have one solution roughly 47% Pd 42% Pt 2%Rh composition - and there are 300g/L PGMs dissolved nicely  Medium is around 3-4M HCL.
But you need to keep the HCL content - for example PdCl2 have poor solubility in water - but in HCL it is greatly soluble - because it forms H2PdCl4 complex acid, which is nicely solvated.


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## JayJayJay (Jun 11, 2022)

orvi said:


> Solutions of H2PtCl6 can become very, very concentrated. You can easily go past 600g/L. We once had a solution of 500g in 500 mL - very heavy  but these can become impractical. With Pd and Rh, I do not have much experience on how concentrated you can go... But I have one solution roughly 47% Pd 42% Pt 2%Rh composition - and there are 300g/L PGMs dissolved nicely  Medium is around 3-4M HCL.
> But you need to keep the HCL content - for example PdCl2 have poor solubility in water - but in HCL it is greatly soluble - because it forms H2PdCl4 complex acid, which is nicely solvated.


Oh wow . 
What would be the effect on dissolving if you added way too much h2o2? Like 30%of the hcl


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## orvi (Jun 12, 2022)

Not much effect. It will catalytically decompose on addition and that´s it.


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## Mdctr (Jun 19, 2022)

eaglekeeper said:


> Question for those over in the EU.... How often does the Cat's there contain Pd?... I have done lots of Cat's here from domestic cars/trucks and to this day I have never found a Cat that tested for Pd.


Are you using AR?


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## orvi (Jun 19, 2022)

I would personally stick to the chlorine/HCL in a bucket, somwhere outside. Put the cats in (not crushed), cover with HCL and day by day, add like 1 tablet of pool chlorine. Or half a tablet - this isn´t some exact science. You just need to have it in the oxidizing leach long enough to dissolve all the PGM coating on the ceramic. After week or two, decant the juice down, cover with another portion of HCL, add chlorine and you will see if there is any more PGMs present - roughly you can judge by the colour of the solution. Then you cement=concentrate values on some metal (zinc or iron work fastest, and since you do not have base metals in, no need for copper).

AR sounds like too much trouble for me. You need to add quite a bit of HNO3 to make appreciably oxidizing mix, that would dissolve PGMs also without heating (you do not want to heat 5 gallon vessel to 60-70°C, if you needn´t to). And then you need to kill all of the nitric - either by evaporation (overkill), denoxing with sulfamic (you need to heat the few gallons of juice to 70 or so °C) or just killing the nitric by adding excess of the metal.


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## eaglekeeper (Jun 19, 2022)

Mdctr said:


> Are you using AR?


Yes, AR

When I test with stannous and a strip of filter paper I will leave it to set for 30 minutes to see if there is any other colors that show around the edges of the Pt stain. Pt is so far all I found..... could just be my luck though.

Or maybe the people I buy from already has a better buyer for the good one's. Selling the lower end one's to me because their shipping cost would eat up any profit... makes more since on their end to go that route. I would do the same thing if it were me.


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## Mdctr (Jun 19, 2022)

eaglekeeper said:


> Yes, AR
> 
> When I test with stannous and a strip of filter paper I will leave it to set for 30 minutes to see if there is any other colors that show around the edges of the Pt stain. Pt is so far all I found..... could just be my luck though.
> 
> Or maybe the people I buy from already has a better buyer for the good one's. Selling the lower end one's to me because their shipping cost would eat up any profit... makes more since on their end to go that route. I would do the same thing if it w





eaglekeeper said:


> Yes, AR
> 
> When I test with stannous and a strip of filter paper I will leave it to set for 30 minutes to see if there is any other colors that show around the edges of the Pt stain. Pt is so far all I found..... could just be my luck though.
> 
> Or maybe the people I buy from already has a better buyer for the good one's. Selling the lower end one's to me because their shipping cost would eat up any profit... makes more since on their end to go that route. I would do the same thing if it were me.


Buying online is risky, alot of people leaching them in and re selling. It's frustrating. I've bought several bad ones. I noticed on one I sprayed water through it and tested with stanous chloride and had posative for pd. . If there's an explanation other then someone previously leaching them please let me know. That's all I can think of. I've gotten pt,pd, and rh out of everyone that I've personally removed.


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## eaglekeeper (Jun 20, 2022)

Mdctr said:


> Buying online is risky, alot of people leaching them in and re selling. It's frustrating. I've bought several bad ones. I noticed on one I sprayed water through it and tested with stanous chloride and had posative for pd. . If there's an explanation other then someone previously leaching them please let me know. That's all I can think of. I've gotten pt,pd, and rh out of everyone that I've personally removed. View attachment 50900


Thanks... I've never thought about testing the wash water. Maybe I should randomly check them...just to keep everyone honest. 

I understand exactly how you feel, buying on line has always been stressful. Always wondering if you got screwed on the deal. What makes it worse is not knowing for a week until it's in the beaker. Now I only buy from the same people that I trust. They work at repair shops and scrapyard, that way I know they have legal possession of them.

I usually get a reasonable amount of Pt from them, so I would think that if they were previously leech I would get very little Pt. 

Hmmm. Maybe my stannous isn't concentrated enough? I have a Au and Pt standard for checking my stannous (tested good), but I don't have a Pd standard yet.

Question: Is there an easy way to test for Rh in solution?


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## Mdctr (Jun 21, 2022)

eaglekeeper said:


> Thanks... I've never thought about testing the wash water. Maybe I should randomly check them...just to keep everyone honest.
> 
> I understand exactly how you feel, buying on line has always been stressful. Always wondering if you got screwed on the deal. What makes it worse is not knowing for a week until it's in the beaker. Now I only buy from the same people that I trust. They work at repair shops and scrapyard, that way I know they have legal possession of them.
> 
> ...


Nothing rhodium related is easy. Testing cheaply is almost a waste of time with the knowledge I have. I've done ALOT of research and haven't been able to find anything relevant. Wish i could be more help. I am currently working on just precipitating rhodium from solution, document process and send it in fingers crossed


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## eaglekeeper (Jun 22, 2022)

Mdctr said:


> Nothing rhodium related is easy. Testing cheaply is almost a waste of time with the knowledge I have. I've done ALOT of research and haven't been able to find anything relevant. Wish i could be more help. I am currently working on just precipitating rhodium from solution, document process and send it in fingers crossed


Thanks for the info.....good luck

I'm probably going to dissolve a gram of my mixed PGM blacks and see if I can detect any Pd from a concentrated solution, if it's there it should show up then.


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## Mdctr (Jun 22, 2022)

eaglekeeper said:


> Thanks for the info.....good luck
> 
> I'm probably going to dissolve a gram of my mixed PGM blacks and see if I can detect any Pd from a concentrated solution, if it's there it should show up then.


Thanks, have you tried to precipitate with sodium hydroxide and test precipitation with stannous chloride?


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## Yggdrasil (Jun 22, 2022)

Mdctr said:


> Thanks, have you tried to precipitate with sodium hydroxide and test precipitation with stannous chloride?


What do you hope to achieve by neutralising the solution with NaOH?
It will drop all the metals as hydroxides which then will need to be redissolved again.
Unless you have sufficient pH control and can perform a controlled hydrolysis that is.


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## eaglekeeper (Jun 22, 2022)

Found it..... After dissolving a gram of my mixed PGM black's and doing a stannous test on the concentrated solution.... Pd showed up late but it showed up. Initially it showed strong for PT only, but after some time Pd starting showing through. The picture doesn't show well, but that is emerald green.

I was surprised how long it took for the color shift to happened, I guess I'll have to wait longer from now on. I'm now curious what all the test strips in my filter paper storage look like.


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## Mdctr (Jun 23, 2022)

Mdctr said:


> Thanks, have you tried to precipitate with sodium hydroxide and test precipitation with stannous chloride?





Yggdrasil said:


> What do you hope to achieve by neutralising the solution with NaOH?
> It will drop all the metals as hydroxides which then will need to be redissolved again.
> Unless you have sufficient pH control and can perform a controlled





Yggdrasil said:


> What do you hope to achieve by neutralising the solution with NaOH?
> It will drop all the metals as hydroxides which then will need to be redissolved again.
> Unless you have sufficient pH control and can perform a controlled hydrolysis that is.


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## Yggdrasil (Jun 23, 2022)

And you tried to say???


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## Mdctr (Jun 25, 2022)

"Thank you sir may I have another."


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## Mdctr (Jun 25, 2022)

Yggdrasil said:


> And you tried to say???


Perhaps PEM stack?


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## Yggdrasil (Jun 26, 2022)

Mdctr said:


> Perhaps PEM stack?


You made a series of quotes and added nothing, so I asked what you tried to say. 
If you have nothing to add to a quote, you are only making noise on the forum, right?
Then you quote me again and say something that don’t make sense in this setting, at least not to me.


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## Mdctr (Jun 26, 2022)

Yggdrasil said:


> You made a series of quotes and added nothing, so I asked what you tried to say.
> If you have nothing to add to a quote, you are only making noise on the forum, right?
> Then you quote me again and say something that don’t make sense in this setting, at least not to me.


The first reply was a submission to your intelligence/authority on this forum. It's from a movie. The second would be a solution to controlling hydrolysis.


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## Yggdrasil (Jun 26, 2022)

The first quote was the one on Friday 10:18 where you said absolutely nothing besides the quotes.

And as far as I know a PEM stack is a fuel cell stack and as such pretty useless in hydrolysis.
Bromate on the other hand can be useful.

And I made no comment to 
"Thank you sir may I have another."


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## Mdctr (Jun 26, 2022)

Also Mathew: 27


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## Mdctr (Jun 26, 2022)

Yggdrasil said:


> The first quote was the one on Friday 10:18 where you said absolutely nothing besides the quotes.
> 
> And as far as I know a PEM stack is a fuel cell stack and as such pretty useless in hydrolysis.
> Bromate on the other hand can be useful.
> ...


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## Mdctr (Jun 26, 2022)

Another slow but successful way. What about diphenyltetradecylmalonamide?


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## Yggdrasil (Jun 26, 2022)

Why do you keep on requoting posts without adding or commenting?
I don’t understand the reasoning to do so.


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## Yggdrasil (Jun 26, 2022)

Mdctr said:


> Another slow but successful way. What about diphenyltetradecylmalonamide?


I hope Lou or the other PGM gurus can pitch in here and confirm or not if this is a feasible process.


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## Yggdrasil (Jun 26, 2022)

Mdctr said:


> Also Mathew: 27


Religion has no place in this forum, it is against the rules.


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