Hacker News Reader

Comment by mk_stjames | Hacker News Reader

This triggered a thought which led me to doing a quick calculation that I haven't done in years...

So, modern pennies are just copped plated zinc. But up to 1982 (barring some small interruptions like the 1943 steel penny) they were 95% copper. There was roughly 2.95 grams of copper in each penny.

Current copper prices seems to be approximately $12.31/kg or $0.0123/gram. That is about $0.036 per pre-1982 penny. Round down to 3 cents/penny to account for recycling costs. If you took all pre-1982 copper pennies you could out of circulation yourself you could make a 3x return!

(I have no idea how many pre-1982 pennies are still in circulation and it seems like this isn't public knowledge. Something tells me this endeavour to recycle them, as an individual, would never be fruitful. Also... my memory is that there is some question of legality in destroying currency en masse...)

View on HN

The metal content value of nickels surged past the face value in 2006, so the law was updated to prevent this very idea:

https://www.usmint.gov/news/press-releases/20061214-united-s...

https://www.federalregister.gov/documents/2007/04/16/E7-7088...

https://www.ecfr.gov/current/title-31/subtitle-B/chapter-I/p...

Pursuant to this authority, the Secretary of the Treasury has determined that, to protect the coinage of the United States, it is necessary to generally prohibit the exportation, melting, or treatment of 5-cent and one-cent coins minted and issued by the United States. The Secretary has made this determination because the values of the metal contents of 5-cent and one-cent coins are in excess of their respective face values, raising the likelihood that these coins will be the subject of recycling and speculation.

Just what i thought: money is really not sustainable. One cannot recycle or wash money. /s

I recall there being people who hoard buckets of copper pennies for this exact purpose. You can't melt them down unless it's for an educational purpose, so they have buckets and buckets waiting for the law to "change" (pun intended).

> You can't melt them down

Sure you can, you just have to find an unscrupulous copper merchant to sell it to. Not a difficult task - they've been around for thousands of years.

The oldest recorded profession?

and North American (possibly) also: https://en.wikipedia.org/wiki/Old_Copper_complex

I'd expected older sites elsewhere, but apparently parts of that complex predate copper workings elsewhere (and the Bronze Age (copper and tin metalworking)).

>> You can't melt them down unless it's for an educational purpose

To educate people about the strength and resiliency of markets.

People have been doing this for years, and poisoning themselves with the resulting vapors. Either copper pennies or old nickels contain mercury if I remember correctly.

Really? I've seen manganese mentioned as a trace element in some coins but not mercury.

That reminds me of British Telecom which is worth less than the value of the copper they own in the ground.

https://www.theregister.com/2011/09/22/bt_copper_cable_theft...

I believe plenty of people already do hoard pre-1982 pennies for this exact reason.

And the laws only apply within the country (although bulk exportation is generally illegal). In Australia in the 1920s and 1930s there was a bit of illegal exporting of silver coins to South-East Asia due to the high silver content.

The right thing to do was maintain the value of the dollar, and therefore the 95% copper penny.

After that ball was dropped, eventually the penny was debased by 1982, ushering in the modern era where all copper wiring and plumbing is increasingly subject to destructive theft like never before.

What's the energy cost of melting that penny? 1.5¢? That'll eat into your profits.

Energy to change copper from room temp solid into liquid is the specific heat of 0.385 Joules/gram * about 1100C + the heat of fusion of 210 Joules/gram, so, about 630 J/g which is 0.170 watt-hours per gram.

A melt of 1,000,000 pennies would be about 3000kg, so 510 kWhr of energy, and using an electric furnace that is about 50% efficient at putting its heat into the melt, that is about 1000 kWhr at the wall outlet. I've been in foundries with crucibles that could do probably about 200kg copper pours, with a furnace power of about 100kW, you'd do a full crucible melt every few hours, and you'd run this continuously until you're out.

If you live somewhere with electricity, say, $0.15/kWhr energy, that is a melt cost of $150.

1,000,000 pennies at 3 cents per worth of copper would be about $30,000 in copper reclaimed over the course of a few days.

So, it would be absolutely profitable in large quantities, assuming you ... already work in a foundry.

Reply on news.ycombinator.com