# Foil converters smelting



## kjavanb123 (Dec 18, 2015)

Greeting,

Since I have built myself a smelting furnace that I have been using to smelt ICs and other components off the circuit boards, I tried smelting 3 batches of foil converters from 3 different cars.

I chose foil converters as smelting them did not involve addition of cryolite as it is damaging to the furnace lining, so here I am going to share with you the process, and very surprising results at least for me.

Here is the photo of material I smelted, lets call this sample batch number 1, it consisted of 4 smaller size foil converters, total weight of 2.870kg.



This is at first when we put them as they are inside the molten lead which acts as the main collector, you can see that the bottom like water,



After addition of flux, only soda ash, slag is formed and removed from the furnace. We add silver metal as collector for PGMs, then lead along with base metals in it are oxidized and removed from the furnace so this silver-PGM alloy remains, and cooled,



We dissolved that silver alloy in nitric acid, the color of solution and late stannous test indicated Pd,



Continue in next post


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## kjavanb123 (Dec 20, 2015)

As silver alloy dissolved in nitric acid, we rinsed it with hot water, and this residue remained at the bottom of pot, at first glance I thought this must Platinum or Rhodium in the foil catalytic converters,



So I dissolved it in AR, and to my surprise it tested for gold! A very concentrated solution of it too, as can be seen here,



I filtered the above solution, and added SMB to percipitate gold from solution and melted it. It weighs 1.2g and assayed 980.



I was thinking how can this be even possible to have gold used in foil catalytic converter, despite the fact we used clean lead and silver for this batch, so we did another batch of foil converters from different model of cars, batch number 2,
Followed the similar procedure as above, we produced a silver rich alloyed with PGMs from smelting the second batch of converters, as can be seen here



Dissolved that alloy in nitric acid, a more concentrated Pd nitrate solution formed, and after rinsing again a residue, upon on dissolving it in AR, we got 1.1g of gold from 3.840kg of foil catalytic converters.

My smelting operator who has been doing that for more than 20 years believes this gold is from converters and not from any contamination from furnace left there from previous ICs smelting.

I have got another batch of foil converters from another car model, 4 of them weighing 4.02 kg, which I am going to smelt to see if gold is from them or contamination from furnace, I just wanted to know others take on this.

On financial note, the gold value alone offsets the cost purchase converters, lead, gasoline and even labor. Palladium which I have only dropped as black powder looks like 4-5grams is the profit.

Best
Kj


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## jimdoc (Dec 20, 2015)

https://unusualuseofgold.wordpress.com/2012/08/07/gold-as-a-catalytic-converter/

http://www.gold.org/sites/default/files/images/wgc_catalytic_converter_final_desktop_180214.pdf


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## kurtak (Dec 20, 2015)

Interesting - very interesting - I have processed a fair number of CATs & this is the first I have heard or seen about gold in them

By the way good to hear from you Kevin - its been awhile

Kurt


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## Platdigger (Dec 20, 2015)

It seems you have done a good job of smelting.
I am curious if you could have forgone the lead and had the same result.


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## kjavanb123 (Dec 24, 2015)

Jimdoc,
Thanks for those two links. The last one from world gold counsil site seems to be more reliable.

Kurtak,
Thanks for your kind words. You gave me the initial motivation to smelt CATs by reading your very informative post about large vs small processing cats. I will smelt the 3rd batch of sample foin converters hopefully this weekend and share the results here. 

Platdigger,
Thanks. I am sure I could not get any results without using lead as the main collector and lowering melting point of foils which is too high for this gasoline furnace.


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## Platdigger (Dec 25, 2015)

Get a lot more heat if you switch to used oil.
Cheaper too.


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## kurtak (Dec 25, 2015)

Platdigger said:


> I am curious if you could have forgone the lead and had the same result.



Kevin can correct my if I am wrong here but no - the lead plays an important roll in the smelting method he is using because the lead is not the elemental metal lead but rather lead oxide (litharge) which is a "strong" oxidizer at molten temps - so at molten temps it oxidizes the base metals but not the PMs (silver, gold & PGMs) thereby allowing the base metals (along with the lead) to be carried off in the slag

Because the PbO oxidizes the base metal is also the reason he is using silver as the collector for the gold & PGMs instead of copper because any copper is oxidized & carried of in the slag where as the silver is not

Because of the lead the smelting needs to be done with a system that scrubs the smelt fumes which is why he is having it done by a professional smelter 

Kevin detailed it al here a bit more :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=22581#p237298 

Edit to add; - because the lead is in the form of litharge (lead oxide) it is actually a "fluxing" ingredient along with the soda ash & not part of the metals being smelted

Kurt


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## kjavanb123 (Dec 25, 2015)

Kurt,

You pretty much nailed it. I will have the photos and results from smelting 3rd batch of foil catalytic converters this week.


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## kjavanb123 (Dec 29, 2015)

All,

Today we smelted foil catalytic converter sample batch number 3, it was 4 pieces with total weight of 4kg, digested the silver alloy in nitric acid, got palladium nitrate and the following black residue,




I tried to dissolve it in hot AR, and it reacted by no stannous changes, I read in Hokes that Platinum takes a while to dissolve in hot AR, so I need to get a tube, and treat this powder with hot AR, then check to see if I get positive respond for Pt.

This batch unlike the other two did not have any gold, and its collector had said their market is weaker compare to other two.

My next phase would be purchasing 20 pieces of sample 1 as it produced 1.2g of gold, and smelt them at once to confirm the gold yield and hopefully expand the operation to 1000s of pieces of sample 1 ans 2.

My last phase on this project would be smelting ceramic converters once without cryolite and once with it and observe the yield.

Best regards
Kj


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## rucito (Dec 30, 2015)

Hello, if this happened to me I will check first the silver which is used


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## kjavanb123 (Dec 30, 2015)

Rucito,

Thanks for your comment but silver used was pure. There is a high possiblity gold is actually from converters. I am going to purchase 20 pieces of foil catalytic converters of type 1, and smelt them to see the result.

Regards
Kj


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## Platdigger (Dec 30, 2015)

kurtak said:


> Platdigger said:
> 
> 
> > I am curious if you could have forgone the lead and had the same result.
> ...


OK Kurt, I came on here this morning because I was thinking about what you said about litharge.
I was thinking about the picture Kevin posted "smelting sample batch 1" were just above he states:

"This is at first when we put them as they are inside the molten lead which acts as the main collector, you can see that the bottom like water,"

So, I don't think he started with litharge as you assumed. Even if he did, he is still adding the foils to molten lead metal.
Kevin please correct me if I am wrong here.
And now I see none of this really matters anymore as Kevin just cleared this up with a post he made to his thread on "Pyrolysis reactor". Were he states:

"then lead is added to the furnace and melted, mixed materials are added, until melted and slag is removed periodacly." 

What he is doing seems to be very similar to what was discussed in a thread were they were doing cpus with lead and a kerosene torch in the Philippines.
In that thread GSP made this statement: 
"Silver used to be removed from lead in a big 5' diameter cupel furnace. Except, the lead oxide was removed from the surface by skimming, I believe."


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## kjavanb123 (Dec 30, 2015)

All,

Sorry about confusion. I believe when my operator start off with lead, due to heat and blown air, all that lead is converted to lead oxide, and that is what really collects the metals, soda ash which is added to materials will remove the non-metallics, and skimmed off.
At final stage, when lead and all other base metals collected by it is oxidized and skimmed off, until only silver alloyed with precious metals remains untouched by oxidation.

Hope that helps.
Kj


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## kurtak (Dec 31, 2015)

Platdigger said:


> OK Kurt, I came on here this morning because I was thinking about what you said about litharge.
> I was thinking about the picture Kevin posted "smelting sample batch 1" were just above he states:
> 
> "This is at first when we put them as they are inside the molten lead which acts as the main collector, you can see that the bottom like water,"
> ...



Platdigger

Thanks for the reply as that is how we keep the discussion going & we all get to learn a little more

Actually though it wasn't so much that I "assumed" but rather I was a bit confused --- I have been following Kevin's threads because like Kevin I am also working on smelting as an alternative to PM recovery from CBs --- the difference being that where Kevin is eliminating the base metals (copper included) in his smelt - I am using the base metals as my collector (copper primarily)

Part of my confusion in my reply to you in this thread was because I had remembered Kevin posting the following in his "Pyrolysis reactor" thread (which was an answer to questions I asked)



> He fired up the big cupola furnace, and in order to avoid blowing the powder he mixed the PbO chunck, soda ash and IC with some water. Then drop shovel of each to the furnace, removing the slag as it burned and PbO melting along with ICs powder.



So my reply to your question in this thread was to point out that - no - in the smelting technique that Kevin is using the lead (ether as Pb or PbO) can not be foregone
as it plays an important roll in the removing of the base metals during the smelt 

At some point in the smelt the Pb needs to be PbO in order for it to preform the task of oxidizing the base metals so that they (base metals) can be eliminated by way of smelting rather then by way of wet chem methods --- So (at least as I understand it) the PbO needed to preform the task of oxidizing the base metals in the smelt can be done by ether 1) using PbO as a flux ingredient to start with - or - 2) start with lead which then needs to be oxidized in the final stage of the smelt

Ether way it is the lead - as lead oxide - that preforms the task of oxidizing the base metals so that they are removed by way of smelting rather then by why of wet chem processing

Now with that all said I have to admit there is a point in this method Kevin is using that I am still a bit confused about (& it may be where I am wrong in my point (1) above)

Because it is the PbO that is doing the task of oxidizing the base metals - is there any reason you can't do the smelt (as I have suggested) with a flux composed of soda ash & PbO so that the base metals are oxidized & slagged off to start with - instead of starting with lead & then needing to oxidize it --- You would of course have to also "start" your smelt with enough silver to act as your collector being as you don't have actual lead as your starting collector 

The other issue would be that the Pb (as PbO) would be lost to the slag rather then recovered for reuse - just wondering if it would work - or am I missing something that would make that not work ?

Kurt


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## kjavanb123 (Dec 31, 2015)

Kurt,

PbO is added and skimmed off as you said its task in smelt is to oxidize the base metals. Soda ash removes the junk from smelt. PbO and Pb that gets converted is also recycled with base metals in it ad reused for next smelt.

Regards


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## Platdigger (Jan 2, 2016)

So basically Kevin, if you continue on with this method "without" a suitable scrubber, you will thoroughly contaminate your environment with lead as well as poison (possibly) yourself and those around you.


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## kjavanb123 (Jan 2, 2016)

Platdigger,

The smelting unit is connected to a lead filtration scrubber and bag house. Local EPA would not allow smelting without installing the required filteration.

Regards
Kj


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## Platdigger (Jan 2, 2016)

ok, sorry Kevin. I am glad to hear it.


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## nickvc (Jan 3, 2016)

Kevin I don't want to rain on your parade but I have been reading about the new technology company that pioneered the use of gold in cats, they were called nanostellar, they went out of business because the price of gold is higher than the other materials that can be used such as Pt, Pd or Rh.
I'd suggest getting a new clean crucible for your next test as I fear any gold you recovered may we'll have come from your ealier trials with chips etc.


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## kjavanb123 (Jan 4, 2016)

Nickvc,

These foil converters are installed on cars manufactored pre-2005, so maybe these days the price of gold higher but I think back then PGMs were much higher in value than gold, I peronally remember the price of Rh was in $2000s per toz.
As for as the gold being contaminated from earlier smelt, that is almost 0 possiblity, due to procedure we use, gold can only be found as trace in the slags, and the gold that ends up in silver alloy.

I am going to smelt 6 pieces of sample 1 today to see what results I will get.

Regards
Kj


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## nickvc (Jan 4, 2016)

Kevin fingers crossed for you for more Au from them 8)


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## kjavanb123 (Jan 27, 2016)

All,

Due to a very busy schedule, smelting of 6 sample 1s is delayed until tommorow. Meanwhile I have been busy refining the black powder produced from smelting 12 pieces of foil catalytic converters.

I rinsed the black powder until the pH showed 7, then dried them as following photo,



Based on what I gathered from generous members here, I multiply the total dry weight of black powder by 20 to calculate the ml of acid needed to dissolve and make a concentrated solution, but instead of adding 118 ml of nitric acid I used less than that, worrying that might make it dilute, and let it heat up for half an hour to dissolve Palladium. As you can see from the picture below,



For next step I prepared a saturated ammonium chloride solution (37g ammoinum chloride salt dissolved in 100ml water), added few mls to the concentrated Pd nitrate solution, it foamed on the surface but did not produce any percipitant, so I brough the solution to a boil, then moved it on to a heater to keep it at near boiling, added about 12g of sodium chlorate, in small increments, to avoid any overflow. Here is what the solution looked like after Pd red salt have been dropped.



Next filtered the green solution and saved the red powder to be treated with ammonia, notice the green solution vs the dark brown solution I started, stannous chloride test on this solution shows very weak sign of Palladium,



These are the Pd red powder left at the bottom of beaker. One thing I noticed those powders sort of stick together during this process unlike gold or silver that floats around,



More photos in next post


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## kjavanb123 (Jan 27, 2016)

In order to remove any impurities from red powder, I rinsed the filter paper into the beaker containing Pd red powder, and stirred it, let it settles, this what it looked like,



So the residue which are pink in color stay in filter while the blue solution is filtered,



To that I added 100ml of muratic acid while stirring, all the sudden that color changed to orange with lots of canary yellow salt percipitated, as seen in this photo,



Let it settles, filteted it and rinsed the yellow powder to another beaker filled with 100ml of distilled water, to that added 10ml of muratic acid, then while stirring added zinc powder, solution turned green and after a while to gray then to clear and this grayish Pd metal percipitated,



After rinsing the produced Pd metal powder wit distilled water until it showed pH 7, I dried it and weighed it, to my surprise I got only 2.4g of purfied Pd metal from 9.4g of black powder I started,



So I wonder what happened to the 6grams of black powder, once dropped out of nitric solution I rinsed those black powder with dilute muratic acid, then with water to reach pH 7. Could they be in those pink residues left from dissolving the Pd red powder in ammonia? That is the only place I am thinking. Your comments always welcome.

Regards
Kj


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## nickvc (Jan 27, 2016)

Kevin I know that finely divided palladium powder will dissolve in hydrochloric and I believe also in water, I'd check all your solutions for values.
Lou or Lazersteve could probably tell you exactly what happened and why if you did lose some of the values, I have always just recovered PGMs for this reason plus the dangers posed by the salts produced, very nasty some of them!


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## Lou (Jan 27, 2016)

You did not fully convert the palladium into its soluble tetrammine palladium (II) complex which prevails in neutral-alkaline conditions. 

The intermediate "pink" product is likely a binuclear complex called Vaquelin's salt. Search up my other posts.

This happens most frequently when the palladium is palladium (IV) not palladium (II), a situation best remedied by sulfur dioxide or, more simply, heating it.

I'm rather impressed with your recoveries given the volume of material and the lead.


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## kjavanb123 (Jan 28, 2016)

Nickvc,

Thanks for your message. I have never heard palladium fine powder dissolve in water. Maybe if it is oxidized with heat then soluble in muratic acid.

Lou,
Thanks for your useful advise here. Just to be on same page with you sir, please kindly advise by heating you mean the red powder or pink powder? 

Today we smelte 7 pieces of type 1 samples, with interesting conclusion, here is the picture show for those of you who are following this threat.

I started out with 4kg (7 pieces) of foil converters, purchased 20kg of lead ingot, this time I timed the entire smelting starting the moment they put to the furnace till the minute the silver alloy is taken off the furnace. Total of 4hrs and 43mins. Since we put them as whole, if we shredd them using the shredder used in tire recyclings, and if we use rotary furnace which can rotate while smelting plus it has higher capacity, then the smelting time can be as little as an hour most.

Here is the foil converters in the furnace 20 mintues into the start, again like the first few batches the part of converters that are submerged in lead pool are melting first



This continues until everything is melted and soda ash is added to remove the junk in the cats,



After all the slags are removed it is time to add silver chloride which is mixed with soda ash to make it stick together more plus this mix and the lead inside would chemically produce silver metals from its chloride form which collects precious metals, this is the silver chloride mixed with soda ash prior to addition to lead,



After silver chloride added to molten lead, stirred a while, the heat is off and oxidized as you can see the black slag on top of orange color lead,



This is the silver alloyed with precious metals is removed from the furnace,



More pics coming up next post


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## kjavanb123 (Jan 28, 2016)

As the silver alloy dissolved in nitric acid, solution turned to light brown as seen the photo below,



The more silver alloy stayed in nitric acid the darker the solution gets, as in the following picture,



So I have to announce that the first two batches of the beginning of this threat that reported gold in the silver is indeed from cross contamination and based on this experiement this batch did not contain any gold, but based on the color of Pd nitrate solution it seems rich in Pd compared to the first 2 batches I did.

I spent $68 on purchasing 7 cats, $33 on lead ingot, and roughly around $18 on gasoline to smelt. So hopefully the Pd recovered will cover those costs.

Hopefully I will get to go after palladium on weekend and will post photos.

Regards
Kj


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## nickvc (Jan 29, 2016)

Kevin I did suspect that the cats would not contain gold, it's a shame as it would have been a great bonus, don't give up you will find the way forward.


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## kjavanb123 (Feb 4, 2016)

Nickvc,

Thanks for your kind words. Again whatever I do here is because of wealth of information members here have provided. Again thanks everyone of you. Lets continue the refining the black powder produced from smelting 7 CATs.

After changing the pH of dark brown solution to 3, by adding soda ash and stirring, I added zinc powder and stirred and got black powder, rinsed few times with tap water until the pH paper showed 7. Dried the powder and it weighed 6.6g

I had recovered 4.6g of black powder from smelting 15 pieces of old telecomm boards, and another 1.4g of gold which assayed 790 though. So old telecomm board, rare but truly rich stuff FYI.

Combined both of them into one beaker, calculated the nitric acid needed to dissolve 11.2g black powder, which according to forum, is 11.2 x 20 or 220ml. I added 200ml dilute nitric acid to the blacl powder, got immediate reaction, but heated it for 20 minutes until all black powder is dissolved as can be seen below,



Let it warm and near boiling, I prepare the saturated ammonium chloride solution, based on calcultion from this great forum, I learned, to precipitate 1g Palladium from solution, 1.5g ammonium chloride salt needs to be dissolved in 1.5 x 100 divided by 37.5 or 4ml of water. 
Since I had 11.2g of Pd in solution, I needed 40ml of ammonium chloride solution as prepared. Added saturated ammonium chloride solution slowly to concenctrated Pd nitrate solution, foams started and lots of fizzing until the color changed to following,



I checked the solution after 30 mintues it looked very green emerald, and Pd red powder in fine forms would go to surface and dropped back to the bottom to look like this,



Here is the red powder that was dropped, rinsed with 15% ammonium chloride solution,



Then I dissolved the powder above using 150ml of ammonia and stirried, after it let settled, there was pinkish residue undissolved, called Vanqualin salt, so I took the advise given by Lou, added 1.2 times the ammonia added, water and heat the mix to 80cand stirred, amazingly all those pink colored dissolved.

Filtered it, and added muratic acid and stirred until I finally got the Pd canary yellow as following,



So thanks again members. Since I ran out of zinc powder, I am going to convert the yellow powder to its Pd sponge using formic acid methods.

Best
Kj


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## alexxx (Mar 19, 2016)

kurtak said:


> Now with that all said I have to admit there is a point in this method Kevin is using that I am still a bit confused about...
> 
> Because it is the PbO that is doing the task of oxidizing the base metals - is there any reason you can't do the smelt (as I have suggested) with a flux composed of soda ash & PbO so that the base metals are oxidized & slagged off to start with - instead of starting with lead & then needing to oxidize it --- You would of course have to also "start" your smelt with enough silver to act as your collector being as you don't have actual lead as your starting collector
> 
> ...



I am realy curious about these exact two same questions.


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## icthuse07 (Jul 18, 2021)

I have been following this thread trying to figure out the complete process and materials I would need to smelt my own foil. I only have 1 foil and until this thread, I couldn't find any info on foils. I currently just get the gold from micro chips of all kinds , can't quite figure out the melting part of it but the chemical part I believe I have down . My question , can u please run thru your exact process for me with precise measurements so that I may simply mimic your process until I get an understanding of how it works . Also , what are u using as a crucible . Seems like all the graphite crucibles I order are all little bitty . Also , could u simply cupel the base metals with lead until the lead soaks into the Portland cement ,taking with it all the base metals ?? When do u add the silver and would silver still be needed if cuppelling it ? I have many more questions, if you guys are willing to coach me a little bit , so thank you for any responses !


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