# Aluminum safe in Iodine leach?



## 924T (Jul 26, 2012)

Would there be any adverse reaction, or dangerous chemical compound formed, by leaching gold off of 
Aluminum, in an Iodine leach (either Povidone or KI+I)?

I've seen the demonstrations on youtube whereby Iodine crystals are put with powdered Aluminum, a few
drops of water are added, and there is a pretty wild exothermic reaction.

I haven't finished retypesetting Hoke's book yet (should be done by this weekend, I hope), so my reading
experience is still pending. In the meantime, I need to find out if Aluminum poses a problem with the Iodine
leach, so I'll know if I need to go out of my way to make certain there's no Al on a circuit board I want to 
do a leaching experiment on.

Any help on this would be very much appreciated-----------I just today terminated a horribly unscientific Povidone
leach experiment on an old CPU chip (that I had forgotten about, so it had been soaking for 2 years); the solution 
was murky and yellowish, and there was some very loose, fluffy orange-ish muck floating around in the jar.

It looked like the gold was still on the chip, so I poured the liquid out, triple rinsed the muck out, pulled the
chip out, and to my surprise, at least 85% of the gold on the lid and the pins was, in fact, gone.

So, a rookie mistake, I threw away maybe $5-$10 of gold, but, at least I got first-hand confirmation that the
Povidone process works, even when done mostly wrong.

So, I'm eager to run an experiment the right way (proper Povidone/H2O ratio, air bubbler, stirrer), to actually
recover some gold with Iodine, but I'm leery, for safety reasons, about the Aluminum.

thanks,

Mike


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## NoIdea (Jul 26, 2012)

Sort of the same as adding HCl with aluminum, it's going to react, may pay to dissolve the aluminium in sodium hydroxide first as your gold will not go into soluton until all the aluminum is gone.

Deano


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## 924T (Jul 27, 2012)

Thanks, NoIdea, that is exactly the answer I needed to make a strategic preprocessing decision.

I've got a few NZ connections----my best friend's wife is from Christchurch, and I've got a friend from KeriKeri (sp?),
so I've found out first hand that the average New Zealander can drink me under the table.

I noted on one of your posts that you seem to hold Thermite in fairly high regard, so here's a fun question:

Have you ever heard of Plastic Thermite?

I invented it back in 1968, did not patent it because I didn't want the world to get their mitts on it via
open access to the USPTO, and got a zero response from our USA D.O.D. about it, which really mystified
me then, and now-----------I can think of many, many applications for the use of it by our Navy Seals
and Army Rangers.

Cheers,

Mike


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## NoIdea (Jul 27, 2012)

924T said:


> Have you ever heard of Plastic Thermite?



Nope, can't say i have, please tell more. 8) 

Deano 8)


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## Lino1406 (Aug 3, 2012)

Aluminum should be dissolved in HCl 
Iodine with Al - a mess
NaOH with Al - a mess


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## 924T (Aug 9, 2012)

Thanks, Lino1406!

Less mess with using the HCl? That's interesting.

That begs a raw newbie question: which would it be easier to cement the Al back out of solution from,
HCl or NaOH? Am I using the right term, 'cement', or should it be precipitate?

Cheers,

Mike


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## NoIdea (Aug 9, 2012)

924T said:


> That begs a raw newbie question: which would it be easier to cement the Al back out of solution from,
> HCl or NaOH? Am I using the right term, 'cement', or should it be precipitate?



Hi Mike - Aluminium is way way up their on the reactivity scale, as a result you will not be able cement aluminium, aluminium is used to cement other metal, base and PM's.

Aluminium hydroxide is a gluggy gooie mess which needs to be left alone to settle then decant, aluminium chloride is not as bad, butt still forms a bit of a mess when concentrate as it hydrolyzes to form a bit of a non-filterable goo. I have used pyrolized electrolytic capacitors to do a final clean, after using iron to drop any copper first, the aluminium drops iron, nickel etc, butt the iron drops as many of it's oxides not too sure about the nickel.

Deano


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## lazersteve (Aug 9, 2012)

I recall reading in a wastewater treatment article(1) that nickel will not cement with aluminum. I actually researched this fact several years back when recovering some palladium from a surface mounted capacitor leach using aluminum. The leach solution was AP which contained nickel and palladium. I used aluminum to recover the Pd, free of nickel, from the leach solution. The left over acid was lime green and tested positive to DMG for nickel after all of the Pd was cemented.

Steve

Citation:
(1) Nickel Solutions and Aluminum- Page 9; Section 2: Conclusions


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## NoIdea (Aug 11, 2012)

lazersteve said:


> I recall reading in a wastewater treatment article(1) that nickel will not cement with aluminum.
> 
> Steve
> 
> ...



Steve, I enjoyed the read, thank you. However….

Under my conditions  , and after dropping copper with iron, filtering, I then put the filtrate in a bucket (both HCl and H2SO4) and introduce aluminium foil, from pyrolized electrolytic capacitors, bit by bit, things happen quickly, well overnight, keep it going till no reaction takes place. I then put into a large, short sided, wide and long, plastic tray for evaporation; a little extra aluminium foil is added, with very little result, colour of filtrate is light tan. I did check the pH and it came back neutral. 

So, in reality, i have saved everything. :shock: , all good tho, i plan to distil then pyrolized in an attempt to recover both HCl and sulphuric acids and iron oxides, plus what ever else was in the mix. This is done after the removal of most of the water, making a concentrated mixture of ferric chloride, ferric sulphate, and other chlorides/sulphates that end up in the mix. The mixture does not really dry out as it is hydroscopic. Sun and air drying resulted in the evaporation of 30lts down to 2. Nothing goes down the drain.

Things at my end differ considerably than that described in the Paper; I still struggle with keeping precise working conditions (pH etc), too many variables, and too time consuming, would rather put it aside and let it do its thing. 

Sorry for the novel.

Cheers

Deano


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## Traveller11 (Sep 3, 2012)

924T said:


> Would there be any adverse reaction, or dangerous chemical compound formed, by leaching gold off of
> Aluminum, in an Iodine leach (either Povidone or KI+I)?
> 
> I've seen the demonstrations on youtube whereby Iodine crystals are put with powdered Aluminum, a few
> ...




Are you saying that Povidone Iodine actually works as a solvent for gold? How long does it take?


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## 924T (Sep 23, 2012)

Traveller11, sorry to be so long in posting a response------I've barely been on the computer for about 
a month.

Yes Povidone Iodine can be used as a gold leach-----try the search terms "Povidone leach" and "Iodine Leach"
on the forum,

and there is something about it in the GRF handbook, which is a free download.

Iodine has a reputation for being slow, and from what I've read, you're well advised to use an aquarium
air bubbler to keep the reaction going.

I did a profoundly unscientific test with Povidone and a gold-capped CPU chip-----it did dissolve a fair
amount of the gold off of the chip, even though I had the ratio of H2O-Povidone absolutely wrong.

The last gallon of Povidone I bought was about a year ago, off of ebay, and was around $28, with free shipping.

Cheers,

Mike


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