Refining catalytic converters [help needed]

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As with any process, they always evolve over time.

I currently use KCl for Platinum precipitations.

A brief soak in formic acid appears to activate the PGMs on the combs to go into solution. I really don't know why at this point, but it may be the active hydrogen provided by the formic acid. It may also be related to the removal of the carbon build up in the cats by the formic acid. Dip the combs in a room temperature bath of formic acid and soak for 30 to 60 minutes (exact time must be determined experimentally on samples as each comb is different due to use and cat operating conditions). Triple rinse with water and proceed with the HCl-Cl routine.

Formic acid pretreatment can increase extraction efficiency to over 90-95% in many cases.

Continue to use the same formic acid bath on each new batch of cats until it no longer aids in the extraction of the PGMs, then replace.

Steve
 
It's the reduction of the oxides, Steve.

PdO and Rh2O3 are both rather acid insensitive.

It is a standard analytical procedure to use sodium acetate/sodium formate to reduce these oxides before doing a wet chem digest and spectroscopy.
 
lazersteve said:
As with any process, they always evolve over time.

I currently use KCl for Platinum precipitations.

A brief soak in formic acid appears to activate the PGMs on the combs to go into solution. I really don't know why at this point, but it may be the active hydrogen provided by the formic acid. It may also be related to the removal of the carbon build up in the cats by the formic acid. Dip the combs in a room temperature bath of formic acid and soak for 30 to 60 minutes (exact time must be determined experimentally on samples as each comb is different due to use and cat operating conditions). Triple rinse with water and proceed with the HCl-Cl routine.

Formic acid pretreatment can increase extraction efficiency to over 90-95% in many cases.

Continue to use the same formic acid bath on each new batch of cats until it no longer aids in the extraction of the PGMs, then replace.

Steve
Click to expand...

Thank you for this great tip. So basically its only used to dip and later we can just discard the acid, right?
Also any great advantage in using KCL and should we use in the same way like ammonium chloride dissolved in water for precipitation? its just in place of ammonium chloride we have to use KCL?

Thanks for the tips.
 
The advantage is that ammonium chloride has complicated waste treatment (needs oxidation with hypochlorite). Ammonium chloride is a source of ammonia when metal containing solutions go through standard hydrolytic waste treatment processes. That ammonia is a chelant which binds nickel, copper, and other metals as amine complexes that do not waste water treat well without the use of sulfides.

To be honest with you, using KCl on solutions obtained directly from catalytic converter leaching will probably result in no precipitate and if it did, most of the PGMs would remain dissolved in solution. This would indicate that the solution would need cementation treatment. Generating large volumes of aqueous PGM solutions is not a good idea: for this reason alone I would suggest against leaching the converter. It might be useful as an educational experience, but it is not something for making money.
 
lazersteve said:
I prefer using potassium chloride to precipitate the Pt. The primary reason for this is that the resulting potassium salt is easier to wash and converts back to Pt metal without the hard to manage ammonium chloride vapors.

The zinc is best applied as turnings. I find that approximately 0.5 to 1.0 inch wide cornets of zinc turnings to have the right surface area to dissolve evenly while producing the best consistency mixed PGM blacks (settle fast and rinse easily). The starting PGM concentration of the solution is another factor that affects the consistency of the resulting mixed blacks.

The dissolution equations of Platinum, Palladium, and Rhodium in a Chlorine milieu are well documented. The primary factors affecting the reaction efficiency and rate are HCl concentration, reaction pressure, temperature, and time of exposure of the wash coat to the solution. Secondary factors include PGM salt concentration and free chlorine.

I have recently found that pretreatment of the combs with formic acid at room temperature can greatly increase the extraction of the PGMs.

I do not process foil cats so I can not help you with them. Here's a quick search result for foil cats

Foil Cats Search

Steve
Click to expand...



Hey Steve!

WOW! awesome stuff here man! so zinc turning to precipitate the PMG's from our main solution and potassium chloride for the solution dissolved with the black PMG power?
and thanks for the search up alot of good info there aswell, the foils still feel like a next level thing..

thanks alot
Shawn
 
lazersteve said:
As with any process, they always evolve over time.

Continue to use the same formic acid bath on each new batch of cats until it no longer aids in the extraction of the PGMs, then replace.

Steve
Click to expand...

How can we know that formic acid stopped aiding in the extraction of the PGMs? After dipping in the formic acid for say about 1-2 hour we follow the normal procedure of HCL/CL everyday and that would leach out the PGM with a postive test of stannous for PGM. So even if we dont dip in the acid we will still get the PGM's so how can we come to know that formic acid is not helping or helping or it has stopped aiding in the extraction. I hope you got you point.
Thanks
 
Extraction is completed when small scale testing of the left over material shows no sign of PGMs. If you have completed a run on the combs and want to confirm your work is done, simply place a small sample of the left over comb in a test tube and extract with AR and heat. Test the AR with stannous and see if any new PMs are present. I demonstrate this on the Fundamentals of Platinum and Palladium DVD which deals with cat recovery and recycling. On the video I test a sample of the beads and find additional Pt is in the material after the initial extraction.

Typically in extraction chemistry three proper leach cycles produces the maximum recovery. After three extraction cycles, the law of diminishing returns kicks in and you are spending more time, chemicals, and money on the extraction process than additional extraction cycles produce in PM value.

Testing is the best means of determining the end point.


Steve
 
Shawn618 said:
... awesome stuff here man! so zinc turning to precipitate the PMG's from our main solution and potassium chloride for the solution dissolved with the black PMG power?...Shawn
Click to expand...

Correct. Use Zinc turnings to scavenge your extraction solution and KCl to precipitate the colored PGM salts from the more concentrated solutions after the blacks are redissolved. Just as I demonstrate on the DVD, but use zinc turnings, not fine mesh zinc on the first go around, and KCl, not NH4Cl on the second.

Steve
 
lazersteve said:
Extraction is completed when small scale testing of the left over material shows no sign of PGMs. If you have completed a run on the combs and want to confirm your work is done, simply place a small sample of the left over comb in a test tube and extract with AR and heat. Test the AR with stannous and see if any new PMs are present. I demonstrate this on the Fundamentals of Platinum and Palladium DVD which deals with cat recovery and recycling. On the video I test a sample of the beads and find additional Pt is in the material after the initial extraction.

Typically in extraction chemistry three proper leach cycles produces the maximum recovery. After three extraction cycles, the law of diminishing returns kicks in and you are spending more time, chemicals, and money on the extraction process than additional extraction cycles produce in PM value.

Testing is the best means of determining the end point.


Steve
Click to expand...
That is what I was afraid that I couldn't make you understand my point, my bad, sorry. I will try once again. I know that we can test and see if any PGM is remaining in combs with a little sample but even if I don't put formic acid leach before any process this is the actual process that testing till we get no stannous test but I am not worried about those processes. I am just asking about formic acid step and you had told that you can discard the formic acid if it is not helping in recovering PGM and then you can discard the formic acid but what is the test or trick to know that formic acid is not helping now. Normally 3 leach is normal stuff we do even if we dont put in formic acid . your point "Continue to use the same formic acid bath on each new batch of cats until it no longer aids in the extraction of the PGMs, then replace." how can we come to know that it is no longer aiding in extraction of PGM. Normal 3 leach without formic pre treatment will also give negative stannous test.
Basically I am asking about formic acid. I hope this make sense. :)

Thanks
 
Formic acid will produce bubbles when it is reacting (oxygen ?). No bubbles, no reaction. When bubbles cease, change your formic.

Steve
 
Carbon dioxide.

Beware using formic with some strong acids, particularly sulfuric--it can make carbon monoxide.
 
Shawn & arsenic

Sorry for the long delay on getting back to this - I have been very busy working on cleaning up the estate of my uncle who recently died

I see that Steve & Lou have already replied with much "good" advice

Concerning processing crushed material which it appears you both have - you are far better off smelting it then trying to leach it - the problem with trying to leach crushed material (as Steve already pointed out) is in wetting it - in other words the problem is in getting your leach to stay in contact with the ceramic substrate & to do so as fresh acids to preform the task of leaching

To achieve this the material needs to be continually stirred to keep the material in suspension in the leach so that it can have continual contact with fresh acid - other wise the material will settle - & when it does it settles fast hard & tight leaving your leach on the top where it is ineffective in doing its task

The other problem is in filtering &/or washing the leach out of it - & for the same reason - the material settles fast, hard & tight preventing effective washing - your best option here is going to be wick filtering & it needs to be a very thin layer of material on top of the filter because if you have to much material on top of the filter it will act like the clay used to seal the bottoms of ponds which will in turn prevent even wicking

If we are talking about a "small" amount of material (a couple of CATs) you could get away with trying to do it in a crock pot (we had an actual 20 liter reaction vessel with stirrer & heat mantle when we tried this at the scrap yard)) --- I would use AR in this case not HCL/CL as my leach - the AR needs to be hot (the reason for a crock pot) & you will need to stir the media as often as possible if you can't provide continual stirring - the leaching will be a day long process & the washing filtering a couple days (waiting on the wicking)

Be aware that you will not be able to leach crushed CAT material with any degree of success on anything larger then a couple of CATs - period - & even on a couple CATs of material your success is only going to be limited for the time & chemical put into it

Smelting (if you can) is really the way to go with crushed material in which cased (based on Lou's good advise) you need to use cryolite as you flux

Kurt
 
Hey guys,

Kurt, sorry for your loss buddy you have my condolences..
(always here for a talk feel free to PM)

thanks for all this info guys i seem to have a good idea of what im doing..

i as of now have a 5 liter glass jar with about 1.6L HCL and Sodium Hypochlorite in it
with 1 full CAT which was 60 percent whole and 40 percent crushed..
i added both in the jar the power settles on the bottom and i stir it every chance i get
and the wholes rest on top.

iv been leaving it out in the sun so it naturally heats up for 90-100 degrees F and at night it would cool back down
and i add about a spoon for concentrated bleach powder which is mostly Sodium Hypochlorite.. its been about 2 days and the solution is yellow-orangish

i believe im expecting a reddish tint?

what is a good Wick TEK
this is the first iv herd of this..

is it something like that cake technique used with cyanide in gold recovery?
...........

ALSO! can i melt Pt with my butane torch?



ill post pictures soon im having phone issues right now..

thanks for all your support! Steve, Kurt, lou, slayer, and Arsenic!
blessed to have an amazing forum and people like you guys!
 
kurtak said:
Shawn & arsenic

Smelting (if you can) is really the way to go with crushed material in which cased (based on Lou's good advise) you need to use cryolite as you flux

Kurt
Click to expand...

Thank you for the reply. Smelting would require furnace right? I have heard that plasma arc furnance is best option to go for crushed honeycomb. Also can this be used for cryolite?
http://www.indiamart.com/fsnproductsindia/foundry-chemicals.html#sodium-cryolite

Or anyone from this page.
http://dir.indiamart.com/cgi/catprdsearch.mp?ss=cyrolite

We have sodium cryolite, potassium cryolite, cryolite powder, etc. So I am a bit confused.
Thanks Kurt for the post.
 
Johnson Matthey uses a reverberatory furnace - here is a video about JMs process

http://www.jmrefining.com/page-view.php?pagename=Video-page&language=

Kurt
 
This is my first post, but I have been reading the forum for a couple of years. Thanks for all the great info.
I am trying my hand at processing catalytic converts. I use Hcl and bleach to the leach the pgm's. I cement the pgm solution with aluminum. After the pgm's drop and settle I'll filter and then transfer the black powder to a beaker and wash with distilled water. Here is where I am having the first problem. Often times I have to leave the black powder in the water for several days. When I come back to it the pgm's I am noticing that some of the pgm's have dissolved back into the distilled water. That to me is odd and I don't understand why that is happening. The water tests positive with stannous. Should I plan to go directly to AR after dropping the pgm's? Why are the pgm's dissolving in the water? If I filter the water, add Hcl, and then add the aluminum again, then I will cement the black powder again.

Another problem I am having is precipitating the platinum with KCl. I dissolved some black powder in AR, denoxed it, and reduced down to a concentrated solution--deep burgundy color. I then added some KCl in small amounts until I did not see any further reaction. I ended up with a canary yellow colored precipitant and the solution continued to be a burgundy color--I assumed the other pgm's where still in solution and that is why the color did not change. My problem occurred when I went to filter the precipitant. I do not have a vacuum filter so I used a Buchner funnel and coffee filters. As I was adding the distilled water to rinse the precipitant, the precipitant began dissolving again. When I was finished there was only a fraction of the precipitant left in the filter. I didn't know what to do so I boiled off the water to get a concentrated solution to see if the precipitant would return--it did not. After the solution cooled, it crystallized into brownish/red crystals. Since boiling off the water didn't make any difference, I added distilled water back to the crystals and I now have a burgundy solution and a small amount of yellow precipitant (from the filtering). So, any suggestions as to what I can do now? Should I try to cement the pgm's again to get them out of solution and start over? Why did the precipitant dissolve with distilled water? Is a vacuum filter required?
Thanks for your help.
 
The refining of PGMs is not the easiest and the one thing to remember is that many PGM salts are water soluble, go back and read Hoke its explained there I think, if not its been posted on the forum and can be found using the search function top right of your screen.
 
I have been reading the forum for 2 years, so I know how to search the forum for answers. I have not been able to find the answer to my questions. There is a huge data of information on the forum and it is difficult to find the right thread that would give me the answer to my questions. Your post would have been useful if you directed me to a thread that addressed the questions that I asked. I have read Hoke and refer to it constantly. I have read other authors also. I have been processing gold without difficulties for 2 years because of this website. I have bought and viewed several DVDs that have been recommended on this forum. I hesitated to make a request for help on this forum because I thought I would be treated as an many "newbies" are treated. I'm not a chemist, but I do have a MD degree, so I'm not asking these questions out of stupidly. I am doing the PM refining as a hobby. I don't appreciate your response, and if you don't have something constructive to contribute to this thread then you need to keep your negative attitudes to yourself. This is a great website and there are some really smart people on this website. I want the smart people to respond to my questions, not the hall monitors. I don't want to tick anybody off, but your response was not helpful.
 

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