# Catalytic Converters Platinum Metals Recovery - VIDEO



## kadriver (Mar 29, 2016)

I've had these sitting in my shop for several years.

This experiment will be a learning experience for me.

For me, platinum in solution is frightening to handle.

As usual any comments or critique are welcome.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=26961

kadriver

edited once to link my new video on catalytic converters


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## 4metals (Mar 29, 2016)

A potential mess became nothing more than a little more rinse work to clean up the reaction that went over all because you had a secondary containment for your reaction. SMART !!!


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## kadriver (Apr 3, 2016)

Here is part 2

https://youtu.be/0fU1MXuD7R0

kadriver


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## kurtak (Apr 4, 2016)

Keven

As usual good video (especially for a first time un-rehearsed venture) 

A couple things I would like to point out - first (in your first video) you said you were going to use the cut away outside shells in your waste solution buckets (I assume to cement other metals out) --- the outside housing/casing/shell is not a good choice for that - they are made of a magnetic SS (stainless steel) designed (alloyed) specifically to "resist" corrosion from the chlorides used for de-icing roads & as we know SS is also resistant to nitric so it wont work well for cementing (anything below iron) from ether a chloride solution or a nitric solution

Also (second video) there is no need to use HCl to rinse the leach solution out of the CAT combs after leaching them - plain old tap water will work fine - yes that means you will be diluting the solution but it does not matter - the zinc is sooooo reactive to the HCl that it can be quite dilute & will still cement the PGMs out "aggressively" --- by using HCl to rinse them all you are doing is adding "more" excessive HCl to a solution that is already excessive in HCl --- that in turn means needing to use more zinc to drop out the PGMs

Also - because the zinc is so reactive to the HCl you "do not" need to use zinc powder &/or shavings - you can use large chunks of scrap zinc (die cast) & at least for sure when you first start the cementing (this will help prevent boil over) & then at most use your zinc powder/shavings to finish off the cementing once the reaction of the HCl with the zinc has slowed down & died off

Here is a pic of the zinc I was using when I was leaching CAT combs on a large volume wherein I was stacking the combs up in a 35 gallon plastic drum as my reaction vessel - I never used powder or shaving - just the large pieces

Kurt


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## Stewill (Apr 20, 2016)

When's part 3 coming out? Super excited to see it!


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## lazersteve (Apr 29, 2016)

Great Videos as usual Kevin,

I would like to chime in on the subject of which form of zinc works best for PGM solutions.

Fine mesh zinc powder (100 mesh or smaller) produces a very finely divided, slow to settle product. Additionally, you need to be sure your zinc powder does not contain the common additive Cab-O-Sil, which is added to prevent clumping and for flame resistance of the powdered zinc. All and all, this is my least favorite form of zinc since the precipitate is so hard to handle. It is very reactive and overflows are a real possibility so be sure to be prepared for them with a catch basin. Zinc powder that does not contain Cab-O-Sil tends to form solid chunks that are hard to remove from the shipping container and have to be crushed before using so they flow freely.

Solid zinc objects have some merit, but it is not free of short comings. Firstly, it is slow to react compared to turnings or powder since it has a low surface area for a given mass. Be prepared to leave your solid zinc hanging for days or even weeks to effect recovery of the PGMs. Secondly, some cast zinc items often are not pure zinc and you end up introducing other metals into the reaction that are part of the 'zinc alloy'. Lastly, and perhaps the worst trait of cast zinc, it that it forms two types of precipitates. The first is a fluffy 'moss' that floats easily (due to hydrogen bubbles trapped in its structure), but breaks apart into super fine dust, similar to the precipitate from powdered zinc. The second form the precipitate takes is a crusty nodular substance on the surface of the cast zinc object. This is the problem precipitate as it requires lots of work to remove or you need to completely dissolve the cast zinc scrap to recover it. I have spent a lot of time trying to clean this type of precipitate from the surface of the solid zinc used for PGM precipitations, and it's no fun and never results in 100 percent recovery unless you fully dissolve the cast zinc object which requires more acid and creates more waste.

Zinc turnings are by far my favorite form of zinc to use for PGM precipitation. Turnings have to be made from known pure zinc bars (I used boat sacrificial anodes) by drilling or milling. The turnings produce a heavy mass of precipitated PGMs that settles fast, rinses well, and filters easily. The high surface area of turnings for a given mass allows for a quick and complete reaction. The cornets of zinc literally grow the PGMs into larger masses as the zinc dissolves and 'unrolls" from the outside in. Since you only add enough turnings to affect the precipitation, there is very little waste and it is quite easy to see the end of the reaction (no more fizzing and negative test to stannous).

As with any precipitation method, there are drawbacks for each type. I choose the one that provides the most complete reaction in one pass, the easiest to handle precipitate, and works in the least amount of time. Zinc turnings win out in my book every time based upon these criteria. I recommend that the readers test each type of zinc for themselves to see what type they prefer for their given task. It's a matter of personal preference which one you choose.

Steve


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## kurtak (Apr 30, 2016)

lazersteve said:


> Solid zinc objects have some merit, but it is not free of short comings. Firstly, it is slow to react compared to turnings or powder since it has a low surface area for a given mass.



True that it is slower to react then turning or shaving or powder - but only a "bit" slower --- at least as long as the leach solution is HCl based (AR or HCl/Cl) & not nitric --- zinc is VERY reactive with HCl & large chunks will react "vigorously" even in a HCl solution that has been diluted 2 - 3 times --- so vigorous it will become a rolling boil with the "chunks" moving & bouncing across the bottom of the reaction vessel --- dilute it 4 -5 time it well still be a relatively vigorous reaction with "lots" of bubbling - the chunks just wont move around on the bottom of the vessel



> Be prepared to leave your solid zinc hanging for days or even weeks to effect recovery of the PGMs



Simply not true --- I have rarely had to wait more then 4 hours (or less) to do my cementing with chunks of zinc --- 4 - 6 hours "max" & that is in cases of "large" volumes of solution so it simply takes longer to use up the large volume of acid (HCl) that is dissolving the zinc - or if it is "really" diluted



> Secondly, some cast zinc items often are not pure zinc and you end up introducing other metals into the reaction that are part of the 'zinc alloy'.



True - but - if you use the electrical conduit connecters I have pictured they are pure zinc --- you can get them "cheap" from most local scrap yards



> Lastly, and perhaps the worst trait of cast zinc, it that it forms two types of precipitates. The first is a fluffy 'moss' that floats easily (due to hydrogen bubbles trapped in its structure), but breaks apart into super fine dust, similar to the precipitate from powdered zinc



The fluffy moss is a problem regardless of what zinc (powder, turnings, chunks) you use including (dare I say) the zinc turnings I purchased from you a couple/few years ago



> The second form the precipitate takes is a crusty nodular substance on the surface of the cast zinc object.



I have NEVER had this problem - at least not as long as you don't use more zinc then the HCl will dissolve - cementing from a nitric solution (Pd that has been dissolved with nitric) is a different story - you will definitely have this problem cementing from a nitric solution regardless of the zinc you use (powder, turnings, chunks)

That is because although zinc is reactive with both HCl & nitric it is much less reactive with nitric so the slower reaction allows the PGMs to crust on the zinc --- zinc is so reactive with HCl (so much faster) the PGMs don't have time to adhere (crust) on the zinc



> This is the problem precipitate as it requires lots of work to remove or you need to completely dissolve the cast zinc scrap to recover it. I have spent a lot of time trying to clean this type of precipitate from the surface of the solid zinc used for PGM precipitations, and it's no fun and never results in 100 percent recovery unless you fully dissolve the cast zinc object which requires more acid and creates more waste.



This is only a problem if you use more zinc then the (HCl) solution will dissolve & it is true regardless of the zinc you use - it just a matter of the size of the PGM incrusted zinc you end up with --- to much zinc powder & you end up with "small" PGM incrusted nodules --- to much zinc turnings = small pieces of PGM incrusted zinc --- to big of a zinc chunk = a chunk (or larger pieces) of PGM incrusted zinc --- in "any" case you will need more acid to rid the zinc

It takes the same "weight" of zinc to cement the PGMs from a solution regardless of the zinc you use (powder, turnings, chunks) so its a question of how much acid you have that determines how much "weight" in zinc you need to do the cementing --- so as an example - if you need a 100 grams of powder &/or turnings - a 100 grams solid chuck(s) will give you the exact same end result of cementing --- so choose your solid piece size accordingly (pic for size example)

Also here is a pic of my zinc barrel - this barrel used to be full to about 6 - 8 inches from the top - so as you can see I have used a lot of zinc chunks for cementing PGMs



> It's a matter of personal preference which one you choose.



I totally agree --- I "personally" like using chunks of zinc because (1) it gives me the "same" end results as powder &/or turnings (2) I "never" have to worry about a boil over (3) chunks of zinc from the scrap yard are cheaper then powder or turnings & even "free" if you do any amount of "general" scraping (my barrel of zinc was totally free from back in the days when I did "a lot" more general scrapping)

Kurt


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## lazersteve (Apr 30, 2016)

Kurtak said:


> Simply not true --- I have rarely had to wait more then 4 hours (or less) to do my cementing with chunks of zinc --- 4 - 6 hours "max" & that is in cases of "large" volumes of solution so it simply takes longer to use up the large volume of acid (HCl) that is dissolving the zinc - or if it is "really" diluted



The statement I made was not based upon the dilution and has everything to do with the well known and documented process of passivation.

The cemented values tend to coat larger pieces of zinc as the precious metals cement out of solution. As this adhered precious metals layer thickens the reaction slows due to the lack of solubility of the PMs in the solution. It takes longer and longer for the acidic solution to reach the solid zinc under the PM layer, thus slowing the process. Smaller pieces of zinc such as turnings or low cross section pieces of zinc do not suffer from passivation to the extent that larger piece do. 

I have witnessed this passivation when hanging solid zinc anodes many times in my refining work.

Steve


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## Stewill (Jun 24, 2016)

Any idea what happened to part 3?


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## Richard NL (Nov 21, 2016)

Stewill said:


> Any idea what happened to part 3?


Sreetips wrote on his youtube channel:"The catalytic converter videos, parts 1 and 2 have been removed. Due to my lack of experience with platinum group metals, I started these videos without knowing what the end result was going to be. 
After doing some more experiments I'll try to finish this and get a video posted. 
Thanks to all my subscribers."


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## kadriver (May 13, 2018)

Finally got the video on this done. I've been waiting years for it.

kadriver


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## golden-puncture (Jun 22, 2018)

what if use aluminium instead of zinc? to get black powder !


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## Yggdrasil (Jun 22, 2018)

Hi!
I used aluminum to cement some hard to cement PGMs, and it initially went very well.
But later I ended up with a thick unfilterable goo in the liquid, probably due to excess Al used.
(Al heatsink for GPU)
I am in the process of cleaning up now. 
So I think it can be used with ease, but make sure to not overuse it.
I have not had the opportunity repeat it to verify the results yet.
So just use the Al with care.


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## g_axelsson (Jun 22, 2018)

With aluminium the oxide is really hard to dissolve (it's sapphire) while zinc oxide is easy to dissolve both in acid and base. It makes it really easy to clean out any excess zinc used.

I suspect that excess aluminium turns into hydroxides and eventually into oxide from reacting with dissolved air. Maybe at the end stage when there isn't that much acid or pgm salts to react so the metal surface of aluminium turns into oxides that falls off together with the pgm:s. 

Reading up on aluminium chloride it dawns on me that aluminium chloride reacts with water forming HCl and aluminium hydroxide. The HCl can then react with more aluminium which would work like a catalyst eating the metal and producing hydrogen gas and aluminium hydroxide.

I don't know if my ideas are true, I'm just speculating about what could happen.

Göran


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## Yggdrasil (Jun 22, 2018)

Yes, my suspicions goes the same directions.


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