CuCl2 (AP) prep question

[chlaurite]

Hey all... Crappy spring, and I still haven't tried my campfire chip cooker yet. New topic though...

So I finally have a good load of card fingers, and wanted to try a standard AP foil removal, following the video on LaserSteve's site more-or-less exactly.

I notice, however, in the first video at around 4m30s, Steve mentions losing gold into solution as AuCl (and never gets back to discussing how to recover that). In the interests of not losing gold this way, I thought I would make up a "stock" CuCl₂ solution ahead-of-time, thereby not needing to worry about too much peroxide in the "real" foil stripping batch.

So I grabbed a handful of pre-1982 pennies, a 1L Erlenmeyer, my acid and my peroxide, and set them doing their thing. Half an hour later, I have the prettiest emerald green solution ready to play with. Except, I realized - I don't actually know how long it will take for (or even "if") the excess H₂O₂ to finish decomposing and go away.

Any thoughts on this? I haven't "lost" anything except a few cents' worth of reagents (and a few literal cents 8) ) if this counts as a completely stupid idea, so feel free to tell me so.

Thanks in advance for any feedback!

Edit - If it helps, I have a handful of palladium/ceramic pellets in my chemistry toybox that I've used in the past specifically to decompose H₂O₂. From what I've read, neither the acid nor the CuCl₂ should have any effect on them; should I drop one in overnight just for good measure?

 

[jeneje]

When using AP, any lose of gold will drop back out as fine black powder. The more copper that goes into solution it will push out any gold that may have dissolved in the AP. Another thing adding an air bubbler will help speed up the process. Hope this helps.

Ken

 

[Claudie]

There is Copper under the Gold foils, to dissolve pennies is a waste of chemicals and pennies. You can use SMB to get the Gold to drop out of the AP solution, but most people here will just reuse the AP until it becomes saturated with Copper, and when that happens the Gold will be in the form of a fine powder at the bottom of the container.

 

[butcher]

Using too much or too strong of hydrogen peroxide will put gold into solution.

The copper chloride is a slow leach for copper, it takes a long time to dissolve larger thicker pieces of copper, but is fairly quick on thin layers of copper.

The light emerald green copper II Chloride, is prime for dissolving copper, as it dissolves copper it will become darker closer to a brown color when it gets saturated with copper I chloride in solution.

Once the Brown solution is so saturated with copper white powders of copper I chloride will precipitate out of solution.

If you added water to the brown solution, you would also precipitate out the copper I chloride as a white powder, leaving a green copper II solution.

Or If you add a little HCl and 3% hydrogen peroxide (or air bubbled in from a aquarium air pump) the water acid and air will rejuvenate the brown copper I and Copper II chloride solution back to the light emerald green copper II chloride solution ready to dissolve more copper into solution.

Copper I chloride the white powder will dissolve in HCl to become the brown copper I & copper II chloride solution (if limited amount of HCL compared to the amount of copper I chloride powder), using more HCl (which also contains water in the 32% acid) will give the green copper II chloride solution ready to dissolve more copper.

Copper II chloride plus copper makes copper I Chloride:
CuCl2 + Cu --> 2CuCl
Water acid and oxygen play a big role in this reaction.

HCl alone will not attack copper, but copper oxide will dissolve in HCl, the oxygen and acid combination form a copper oxide allowing the copper oxide to form copper chloride, then the copper II chloride will dissolve (oxidize) more copper into solution as the copper is oxidized the copper II chloride is reduced to copper I chloride, when anything is oxidized (loss of electrons) something else is reduced (gain of electrons).

Gold will not dissolve if the solution is not oxidized strong enough to oxidize the gold, concentrated hydrogen peroxide can oxidize the gold, in this leach we only wish to dissolve away the copper and not put gold into solution, leaving us the gold undissolved usually as foils.

If we over use hydrogen peroxide or use concentrated peroxide and put gold into solution the gold will eventually plate back out onto remaining copper as the copper II chloride becomes saturated with Copper I chloride (indicated by the brown color), but until all of the copper is put into solution our gold black powder will be plated to remaining copper, once all copper is dissolved, as long as we do not put gold back into solution (overuse of oxidizer) the gold would remain as a black powder in the bottom of the vessel.

We would much rather have foils than our gold as black powder, as it is easier to deal with without lose of our gold, so it is best not to put gold into solution in the first place.

We see here the copper II chloride leach is a great leach for us to use to dissolve copper away from our gold.

Copper II chloride will also dissolve other base metals into solution, but this will contaminate our leach, and once saturated with base metals above copper the base metals higher in series will push our copper out of solution until we no longer have a copper chloride leach, iron for example will replace copper from solution forming an iron chloride solution, for a better understanding of this Google and read several topics on reactivity series of metals, and replacement chemical reactions.

If we keep base metals out of our copper chloride solution and only use it to dissolve copper we can keep rejuvenating and reusing it to dissolve more copper, the solution does grow in volume over time, if you have a large volume of solution, which is still healthy (not contaminated with base metals below copper) one thing we can do is evaporate it down to a thick syrup add water to precipitate out copper I chloride powder and some copper II chloride solution, store the powders in a little water, which can be made back into solution with HCl later, or I can use the excess unwanted solution to attack other base metals (like iron, dissolving them into solution before treating the solution for waste.

Any one using this leach should read and study the the document provided by Laser Steve on his web site, the document explains how the leach works and how to use it.

 

[bswartzwelder]

If the pennies were minted in 1983 or later, they are NOT copper. They are zinc with a very thin layer of copper on top. If they were minted before 1982, then they are copper. In 1982, the mint changed from the familiar copper pennies to the zinc pennies. Copper pennies weigh in at approximately 2.11 grams while the zinc replacements are less than 2 grams. I believe their weight is about 1.76 grams. DON'T quote me on the weights, but it is easy to find the exact weight doing an Internet search. Just my .02 cents.

 

[FrugalRefiner]

U.S. pennies minted from 1864 through 1982ish weighed 3.11 grams when new, with the exception of the 1943 steel cents. Pennies minted from 1983 to current weigh 2.50 grams.

The pre-1983 cents were 95% copper, with the remainder being either zinc, or a mixture of zinc and tin depending on the year they were minted.

I posted this summary of U.S. Coins and their Metal Contents some time back.

Dave

 

[chlaurite]

If the pennies were minted in 1983 or later, they are NOT copper.

So I grabbed a handful of pre-1982 pennies [...]

8)

And FWIW, you can't trust 1982 pennies without weighing them, because they minted both compositions, solid copper and copper-clad zinc, in that year.

 

[FrugalRefiner]

If the pennies were minted in 1983 or later, they are NOT copper.

And FWIW, you can't trust 1982 pennies without weighing them, because they minted both compositions, solid copper and copper-clad zinc, in that year.

You can't trust 1983 or 1984 either. While most of them were the new composition, there were a few '83s and '84s minted on the old planchets. They're worth a couple of cents to collectors. 8)

Dave

 

[bswartzwelder]

I know the mint makes mistakes, but I hadn't heard of any copper 83's or 84's. Sounds like either a mint employee stashed a few or found a few under a locker or machine and tossed them into the hopper. I'm shocked that they aren't worth much more. I have been saving coins for quite a few years and just recently started sorting them. Rolled a bunch and cashed in a few. Found one quarter with 2 heads. It's a homemade fake, although a very good one. One side has a Philadelphia mint mark and the other side has a Denver mint mark. The weight is slightly off. To this day, I haven't found any visible errors to show where two heads have been machined and put together. At first, before I weighed it and saw the two different mint marks, I really thought I had something of extreme value. Now, it's just a conversation piece. I found it in circulation. I'll bet the maker put it in his pocket with other loose change and spent it by accident.

 

[FrugalRefiner]

I know the mint makes mistakes, but I hadn't heard of any copper 83's or 84's. Sounds like either a mint employee stashed a few or found a few under a locker or machine and tossed them into the hopper. I'm shocked that they aren't worth much more.

I found that information while researching the metal contents of U.S. Coins. There aren't many, but they do exist. If I remember correctly, they found some old stock of the copper planchets in each year and included them in production.

I can't find the reference for the 1984, but here's a link to an article on PCGS' site about the 1983 - PCGS 1983 Copper Cent

Dave