inquartation gold coated mylar and stainless steel

[Anonymous]

Hello all. I dont like making new threads on well populated boards but I didnt find any particular thread that seemed proper to top for this particular few questions so....

First off, I have aprox 1 troy pound of crap metals recovered from a vacuum coater. My customer said to the best of his recollection there was maybe '1, 2 or 3 ounces of gold' in the material and the remainder is roughly equal parts of silver and copper. IF the gold content is on the high side this seems perfect for inquartation. if not is there anything in particular I should keep in mind when digesting material with lower than normal gold content? All of the material including the gold was 4 9's pure - any guestimate as to how well inquartation will work to remove the copper and silver?

Next...

I have 3 square feet of stainless steel sheet (probably 304, but I'm not 100% on that) that contains about 3 ounces of gold coated on one side (again from a vacuum evaporator) any suggestion as to the best plan of attack to recover this metal? The back side of the stainless sheet is also coated with SiC if that is any issue.

lastly...

I have a number of rolls of gold coated mylar, surplus from nasa. Does anyone have any idea how thick these gold coatings may be? I did a quick google and one reference I saw listed 20nm gold for a common coating on mylar. at that rate there would be about .2 cubic centimeters per square meter of film and I have many hundreds of sq meters. Any idea as to how it could be recovered?

Again many thanks in advance!

 

[lazersteve]

Welcome to the forum,

The first thing to remember is to test everything first on a very small scale before you commit to a large scale reaction and waste a lot of chemicals.


The gold that started out as 4 9's is not 4 9's anymore and will require purification to get back close to that. Once pure gold is alloyed with other metals it is no longer pure, until refined again. All gold, no matter the current purity can be refined back to high purity.

I would try 50/50 nitric on a small sample of the gold alloy. The silver and copper should go into solution and the gold will remain as a spongy mass or a fine powder depending on the base metal and silver content. The gold will then need to be refined using AR or HCl-Cl.

For the stainless steel, you should be able to dissolve it in hot muriatic or sulfuric. The gold will remain undissolved. The gold will then need to be put in solution with AR for refining.

The mylar melts at a fairly low temperature and becomes a clear liquid. The gold can then be dissolved and refined.

Remember start very small and confirm everything goes as planned.

Steve

 

[Anonymous]

Steve,

All of the gold in question has been e-beam vacuum evaporated from graphite crucibles? is there any reason to not treat it as fine gold that has simply been alloyed with /deposited on other high purity metals?

That is why I had asked how well the nitric will remove silver and copper from gold as so long as i can get 23k+ I can sell it as such to a local metals dealer at 95% spot. I doubt i'd do any better than that if i actually tried to get it back to fine levels of purity.


With regards to the stainless sheet, it's only maybe 10 mils thick and the back side is coated with SiC as I mentioned. silicon carbide isnt attacked by h2so4 or hcl. thats a whole little surface area to have the acid attack from.

Finally as to the mylar. I'd guestimate were talking about 100 to 200 lbs of material (its been a while since I lifted one of the rolls). even if i tried to melt such a large volume of material down wouldnt i just make a collodial suspension of gold flakes doing that? I was thinking of slitting the material into manageable widths and then loosly rolling it so that it could be placed into a bucket and then leach the gold of the mylar - but then the question becomes - with what?

TIA

 

[lazersteve]

The stainless may strip fine in the sulfuric cell.

AR or HCl-Cl will attack the very thin gold on the mylar if it is not covered with mylar on both sides.

The copper, silver, and gold is most likely now an alloy to some degree and will need to be chemically separated as I previously mentioned. At the karat you mentioned (1-3 ounces per troy pound) you have a 2kt- 6kt equivalent alloy. Hot dilute 50/50 nitric should do the trick. At that level of base metal content the gold will require refining to get back to 23kt +.

Do you have any photos of this scrap?


Steve

 

[Anonymous]

I should think the Mylar film could be reduced by burning the plastic base and leaving a gold residue. Which could then be reduced in an AR solution. Just my guess, try small batch first.

 

[Lou]

I'd like to see some photos as well.


He seems to be getting a lot of materials science waste. When someone talks of 25 ozt. of 75% Pd/25%Ag I am already suspicious Probably/possibly from the space program. In which case he just hit the lotto. I hope he can get the sputtering targets that were used in the PVD, they should still be pure and they sell well to collectors of vintage NASA stuff.

Steve gave excellent recommendations on what to do.

Only change I would do is for the stainless with the gold on it, since it is thin, I would just coil it and chlorinate. Cl2 does a remarkable job of removing thin gold and carrying it to someplace else as AuCl3. That's either added to HCl and reduced as normal, or heated in hydrogen, or heated a little further until it dissociates back to Cl2 and Au. Easy work with a quartz tube, tube furnace, and about 3 hours of sitting around watching it go. Gold by that method (assuming no PGM content) will run far above 99,99% pure.


As I said before, if you don't want to bother with it, I can and I will and am willing to do it much cheaper (I love working with this type of stuff!!!) If you find any sputtering targets, let me know. I've attached a photo of a large (3,8 kg, 99,95% Hafnium target, I had a smaller one as well that was 2,3). They are usually disks, smooth on one side, rough on another.
I collect these so let me know



Lou

 

[Anonymous]

Lou,

I'll try to get some photos taken shortly.

you guessed halfway right - it is PVD material, but it isnt from nasa. It's from an electronics r&d lab.

after playing around with the stainless some it seems like most of it will come off via simple mechanical action.

BTW - did you ever get my last pm on the pd? if not i had basically said that I will probably hold off recycling the material at this point as i may get more and wanted to know if you could convert it to hallmarked precious metals instead of returning back what you recover.

BTW - this isnt the jackpot. I once bought a large lot of hardware from pinellas plant in florida. it was an old DoE facility. the machine in question produced ultra high precision quartz crystal time bases for weapons. the electrodes were, yup - you guessed it - gold.

I wont say how much for fear of being labled a fish tale teller, but suffice it to say it was well more than what I'm talking about here. well more by FAR.

brav01,
if i did that then wouldnt all of the gold go up the flue? dont forget the only number i have seen thus far with regards to the thickness of the coating is 20 nanometers. thats a darn tiny cross section.

the mylar is metalized on 1 side, with a silver color coating first then gold over it.

 

[Lou]

Sir, I received no such message from you. As far as hallmarking goes, something can be arranged. I only process it chemically, I'll have others melt it inductively. It comes down to volume of material--is it cheaper to sell a few ounces of palladium as scrap, albeit 99,99% fine scrap and lose 15-20% of spot, or is it better to pay for an assay, hallmark, and it to be cast as well? This depends on volume. If you have 100+ ounces of material, it is well worth it to have it assayed as you can demand a higher price for it.

Let's say you get 85% of spot on 100 oz.t 99,99% palladium that's still considered scrap by the refinery (no assay). That means they get 12 oz free, because with an assay. With an assay, you would probably expect ~97% of spot with them making only 2-3 oz. Pd profit off of you because they either stockpile and speculate on it, ship it out as commercial sponge for alloying, make their own alloys and formulations, or whatever they fancy. That's how it works.


It would be no fish tale to me--anything that goes into weapons manufacture, especially in the high precision parts arena is always "no expense spared". I could tell a few stories about ridiculous finds and near misses as well. I wouldn't mind hearing about some of your scores--it's good information to know and I would be glad to trade sources for high yield items.


Lou

 

[Anonymous]

Lou,

I'll post some photos tomorrow when I have better lighting, it was overcast most of the day today.

I'm new here - but it seems like most of the people in this forum have an addiction to photos of all things shiny - so long as it has the proper atomic weight

So int he mean time Ive attached some photos of my gold nugget collection - not nuggets as in recovered scrap but the sort that is dug out of the ground in australia. hopefully that will tide you guys over for a little while and serve to keep the much apreciated input coming! NO you may NOT refine them

BTW - i dont have much along the lines of sources for scrap. The material I get now is from a single lab source that I have. The previous story I mentioned was a one off find. And likely a once in a lifetime find. it was large enough to buy a modest home - even back in the day of 300 $/oz gold. I'll post back with the .50$ version of the story if you really want me to...

thanks again.

 

[Noxx]

VERY VERY nice nuggets !

 

[Lou]

Seems like you might have as much of an addition to the yellow metal as we do!! Beautiful nuggets! You found these yourself? Or is it a mixture of bought/found?


Do tell your $0.50 story, I'd love to hear it. This might trump my favorite story of ridiculous government-funded spending....