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smelting pennies


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Ok all of this is hypothetical... currently pre 82 pennies are worth double their face value in copper at 95% copper 5% zinc. If someone wanted to smelt the copper out of them and separate the zinc could one do this simply through heating them? I know zinc melts at a lower temp than copper so would you be able to separate the melted zinc before the copper melted?. Now I know that it is illegal to deface currency and  I also know the dangers of melting zinc... fumes.. positioning etc. I am just curious if this is a possible process. Maybe if one day the gov allow us the use of scrapping pennies. I know a lot of people are hoarding them right now.

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The mix is an alloy of the two metals.  They will not separate just from melting.  Think of bronze...usually a mix of copper and tin , and it does not separate when melting to pour art castings.   Or brass, which is usually copper and 10% zinc.  A chemist would have to chime in here to explain how to separate them chemically, if it is even possible.

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If I took a hundred pound ingot of 95-5 copper/zinc to my scrappy, he would shoot it with the xrf and pay me for 95 pounds of copper and 5 pounds of zinc. He does the same when I carry a piece of mystery metal up to the counter to buy it.

For example I was there a couple of days ago and grabbed a handful of "stainless" rod for pinning knife handles. When he shot them they were some alloy really high in nickel and going to cost $3 a pound instead of the normal $.75 so I didn't buy it.

 

mark

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Not saying I melted pennies before, but........I've had them well above zinc melting temps before without any appreciable deformation of the copper ones outside of some oxidation on the outside.

 

A few copper ones not sorted properly from a bunch of zinc ones on the other hand, sometimes come out of the bottom of the crucible yellow and "brazed" afterwards. A cool looking, but probably stupid effect given the chances of getting seriously ill from doing this.

 

I suppose if you melted the copper long enough, maybe some of the zinc would burn out or be given off as fumes. I seem to remember hearing that in professionally recycled brass, some of the zinc was lost when it was remelted.

 

Either way, melting pennies at home without all proper precautions is a good way to get fume fever. Doesn't seem worth the risk to me, even to get copper.

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Had this argument once or twice.

 

There have been laws on the books in the states against defacing money, primarily with the intent to keep people from say, scrapping $5000 in pennies for $15,000 in copper or zinc.

 

They have gone on and off the books periodically, but even when they're in place, they usually on focus on people who are destroying large quantities of cash. Not some guy in the backyard that melts down two or three bucks in small change for a hobby or an art project.

 

The big law otherwise is that you can't change money with the intent to defraud someone, and that one stays on the books.

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I chased this down in pursuit of something else but it applies directly here so I thought I would share.  I know you are already aware of the illegality of it, just wanted to cite the reference for posterity.  plus, melting them down specifically to harvest them as a raw material was specifically illegalized on its own to prevent shortage and costs incurred to re-mint them, entirely separate from the clauses covering defacing and mutilation.

 

it appears that the interim rule against melting down nickels and pennies was finalized in 2007 and is in effect

http://www.usmint.gov/pressroom/?action=press_release&ID=771

"Specifically, the newly enacted final regulation prohibits, with certain exceptions, the exportation, melting or treatment of one-cent and 5-cent coins. Some of the exceptions allow for small amounts of these coins to be exported as pocket change, and for recreational and numismatic purposes. Other exceptions include the treatment of minor quantities of these coins for educational, amusement, novelty, jewelry and similar purposes. However, the public should review the regulation for precise terms and limitations of the exceptions." excerpt from the usmint link

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  • 2 weeks later...

So it's illegal to melt the coins to recover the copper and zinc value, but you can still melt it to make mokume or similar foofaraw.

 

Of course, all this would be moot if you weren't showing up regularly with ingots.  One visit with an ingot that's reasonably similar to the chemical make-up of coinage isn't going to warrant close scrutiny.  Repeated visits, or showing up with a huge ingot... that's another story.

 

Is it worth the trouble?  Personally, I hunt down old copper-tipped soldering irons if I want a big chunk of copper to play with.

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  • 4 weeks later...

So it's illegal to melt the coins to recover the copper and zinc value, but you can still melt it to make mokume or similar foofaraw.

 

Of course, all this would be moot if you weren't showing up regularly with ingots.  One visit with an ingot that's reasonably similar to the chemical make-up of coinage isn't going to warrant close scrutiny.  Repeated visits, or showing up with a huge ingot... that's another story.

 

Is it worth the trouble?  Personally, I hunt down old copper-tipped soldering irons if I want a big chunk of copper to play with.

 

Few places will acept an angot, because it is too easy to fake its true content, all you need is accurate weight for size, coul be anything inside the ingot.   I was also told that,  with them paying the same amount for the origonal item as the newly manufactures shape IE the ingot, and it costs more money  to heat to melt into an ingot, there is no reason to process unless it is to defraud them.

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  • 7 years later...

1982 and older pennies w/ a copper to zinc ratio by mass of 95:5 will melt at 1024C. It's best to pour the metal into molds once the temperature reaches above 1120C. This will help make the pour much smoother and gives a nicer end result. This requires the use of a serious melting forge. Propane gas wouldn't get hot enough. After melting the pennies and pouring them into a graphite mold, they will need to be refined by electrolysis to crystalize out the pure copper while leaving the zinc and other impurities behind. Electrolyte of choice is copper sulfate which is very water soluble. You can find the entire procedure for electrolytic refining online. Instead of melting the pennies down, you can figure a way of refining them directly with electrolysis by using a vaccuum filter bag cell design. Check out Sreetips on youtube for silver cell designs.

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Welcome; BTW that thread was 7 years ago!  Also: propane gas can melt steel which takes a way hotter temp than copper takes; I've accidentally done it in my propane forge and saw a friend do it accidentally in his propane forge as well.

Does there need to be a mention of "Check the last posting date of a thread" in Read This First?

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  • 7 months later...
On 2/2/2014 at 1:44 PM, Stefflus said:

I was wondering if this couldn't be done with selective oxidation of a melt, so I did a google search.

According to this PDF it can't, but they mention "Vacuum treatment" of the melt, what process is that? (page 11)

http://www.metallurgie.rwth-aachen.de/data/publications/2333.pdf

Yes this is true you have to retort zink oxide just like amalgam back to mercury  but I 

 

DO NOT RECOMMEND THIS IF YOU DONT KNOW YOUR BASIC REQUIREMENTS AND CARE.......

 

Safe poor 

Poor on

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Cooter; are you interested in smelting---taking ore and extracting metal from it or melting---heating up metal till it melts and then casting it.  Your name seems to indicate one but your posts seem to be about the other.  I've done some of both which is why I wanted to know.

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