# Using Dilute HCl/Cl to Process Catalytic Converter



## kadriver (Dec 26, 2011)

I have four catalytic converters. I do not know if they contain pellets or honeycombs yet - I need an angle grinder to get at them.

I am going to process them for Pt & Pd using lazersteve's DVD as a guide (and Hoke, of course).

I have all the chemicals, and other special items needed. I just ordered 2 fused quartz dishes ($50 each) for incinerating the powders.

I was looking for info on a bucket heater (they are expensive!) when I came across a post entitled "stannous chloride problems" from Jan 2011.

In that post I discovered that a bucket heater may cause a problem when using HCl/Cl to leech PGM's from the cats. The post stated that chlorine may be driven off too quickly by the heat causing ineffective removal of the PGM's, and that cold with a long leech period was a better method.

Also, it was mentioned that using dilute (50/50) Hydrochloric acid/distilled water produced better results than using 31.45% hydrochloric acid right out of the bottle from Lowes. The process was quicker [using dilute HCl], the author said, and less zinc was needed due to less acid in the batch.

These are all good things to know - if they are true. Does anyone have any experience that can be shared with respect to the processes mentioned above?

Thanks! - kadriver


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## lazersteve (Dec 27, 2011)

Search the forum for bucket heater and you should find a link I provided.

If you can't find it let me know.

Steve


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## Anonymous (Dec 27, 2011)

kadriver said:


> I have four catalytic converters. I do not know if they contain pellets or honeycombs yet - I need an angle grinder to get at them


Usually converters with pellets will look the same.I have yet to see one that was not the same basic shape as any other,and every one I have seen has a "filler plug" on one side,so the pellets can be filled into the converter after it has been manufactured.
And most honeycomb converters I have had,have ridges or rings stamped into the steel,to keep the honeycombs from moving.But some honeycombs converters have a honeycomb the entire length of the shell,and this eliminates any need for the retaining rings.


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## kadriver (Jan 21, 2012)

I got my first platinum metal today.

Yesterday I did a course filtering from leaching two ceramic inserts.

Today I did a fine filtering and then heated the solutions to drive off excess chlorine.


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## kadriver (Jan 21, 2012)

Tested with stannous chloride using a piece of paper towel.


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## kadriver (Jan 21, 2012)

The zinc powder was caked together pretty good, so I used a mortar & pestle and ground it as fine as talcom powder. It reacted quickly and I only used a little zinc to get all the PGMs to precipitate.


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## kadriver (Jan 21, 2012)

A second stannous test shows no reaction. I kept adding fine zinc powder until the solution turned a pale green/grey color.


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## kadriver (Jan 21, 2012)

I allowed the black PGM powder to settle, then poured off the barren solution and saved it. This is the black powder left in the bottom of the container.

It looked and acted exactly like gold powder after precipitating with SMB, only this is black and not brown.


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## kadriver (Jan 21, 2012)

I don't have a hydrogen torch yet. I am working with the guy at Airgas to get that all set up.

For now, I will just keep it in the bottle and keep adding to it as I go.

Then once I get a good amount of it I'll do a melt and get a button.

Thanks for looking - kadriver


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## kadriver (Jan 22, 2012)

I just realized that this precipitated black powder in mixed PGMs. It will need another treatment in hot AR as per lazersteve's DVD.

Then precipitate the platinum salt with saturated ammonium chloride, filter and calcine to sponge.

kadriver


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## lazersteve (Jan 22, 2012)

You can also treat the mixed blacks as per Lou's instructions to separate them with a little less effort:

Separating Mixed PGM Blacks

Steve


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## kadriver (Jan 23, 2012)

lou's instructions are in red letters:

1.) cement everything with zinc (or even copper, but I caution anyone who wants to plate with their rhodium to never introduce copper!) [<1 hr]

I have already done this step - the black powder in the flask is the result.

2.) take this reduction product, rinse it clean with NaOH to remove zinc. [<1h]

I am completely unfamiliar with this step. What concentration of NaOH? Do I boil in NaOH? Can I use red devil drain cleaner? Seems straight forward, but some guidance would be helpful to me with this new process - thanks.

3.) Add nitric acid and the solution will turn yellow then deep brown as the palladium dissolves. [<1h]

No problems with step #3

4.) decant, add water, decant, add more concentrated nitric and heat. Do this until the solution no longer goes yellow (shouldn't take long) [<1h]

No problems with this step (#4).

5.) Digest the residues in concentrated sulfuric acid, it will go yellow then a very brown-red as temperature increases. Repeat until no color takes to the acid. [<4h]

Step 5 is a new process that I have not seen before. What, if anything, is in the sulfuric acid after completing this step? Should it be saved for values?

6.) What's left is mostly pure platinum. Digest in HCl to which hydrogen peroxide is carefully added at room temp. then boil the solution once to rid it of chlorine. [<3h]

What percentage of hydrogen peroxide should be used? Can I use 3% from the drug store? Would I be better off getting a higher percentage of H2O2?

The rest of this process is new but completely do-able at my level.

7.) precipitate by dropping your solution into a saturated solution of ammonium chloride. Whatever the weight of the platinum was, 1.1X that in ammonium chloride is perfectly sufficient to precipitate the platinum and leave enough ammonium chloride in the solution to drive solubility down.
8.) Your ppt. should be a nice yellow without reds and especially any green (otherwise you had not removed all the rhodium down to <0.5%). If you do get some green, heat the precipitate in the minimum amount of water until it dissolves to give a yellow solution. Add a little more water and cool slowly down to 0*C. At that point, I add dropwise saturated room temp. ammonium chloride that is 0.05M in H2SO4. This should get rid of the rhodium.

Good luck, have fun, and don't get anything on your skin!

Lou


Thanks for leading me to this post - it looks very compact and concise!

kadriver


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## lazersteve (Jan 23, 2012)

Please read the remainder of the thread in the link used to answer your other questions, they were all asked and answered in that thread.

Steve


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## kadriver (Jan 23, 2012)

Got it - thanks


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