How much copper in an average PC?

May 18, 2006 12:12 PM

How much copper is there inside an average PC?

I'm trying to find out how much copper, palladium and other valuable metals are contained inside the average PC. I'm most interested in copper, but info about any other valuable metals would be great. Can anyone point to some good sources on this?

posted by nyterrant to computers & internet (11 comments total)

If you want to get into copper recycling, you should take a careful look at old building wiring instead. Computers have copper in them, but it is tough to get it back out.

Office buildings often have hundreds of miles of old phone and networking cables that are not up to spec for modern gigabit-speed networks. Often contractors will be paid by the facility owner to rip out the old cable, then they turn around and sell the copper to a recycler for an even greater profit.

A decommissioned phone switching center would be a gold mine of high-quality copper. Switching centers that are active and operating will have a significant quantity of unused copper, but the danger to in-use lines is far too great for them to let anyone remove the unused stuff.
posted by b1tr0t at 12:33 PM on May 18, 2006

Let's just say you would need vast numbers of computers to make recycling the metal in them worth your while.

One old, copper hot water heater > Enormous number of computers
posted by MasonDixon at 1:07 PM on May 18, 2006

According to the Silicon Valley Toxics Coalition, an "average" desktop computer will have about 4.85 pounds of copper. They use 70 pounds as an average desktop's weight, and they estimate that 6.9287% of that weight is copper. They also list the copper's recycling efficiency at 90%.

But it occurs to me that you didn't say anything specific about wanting to reclaim the copper, just that you were interested in how much was there. The SVTC lists all the elements involved in making this same average desktop, so take a look. The data is about 10 years old, according to the citation at the bottom of the page.
posted by dammitjim at 2:14 PM on May 18, 2006

Copper isn't a "valuable metal". Today's prices per metric ton on the "London Metal Exchange":

$2,971 Aluminum
$1,202 Lead
$20,800 Nickel
$9,070 Tin
$3,668 Zinc
$8,590 Copper
posted by Steven C. Den Beste at 2:18 PM on May 18, 2006

dammitjim writes "4.85 pounds of copper. They use 70 pounds as an average desktop's weight, and they estimate that 6.9287% of that weight is copper. "

They must be talking about the whole thing including a CRT(lots of copper in a CRT). Even in the IBM PC days the computer itself didn't weigh 70 lbs.

I'd bet a modern beige box has less than a pound with the vast majority being essentially unsalvagable.
posted by Mitheral at 2:50 PM on May 18, 2006

I can't come up with any numbers, but I did just want to say that if you looked inside my PCs you'd see a significant amount of copper used in the heatsinks for the CPU and graphics card. Such products may alter the average amount of copper in a modern PC vs one made back when cooling wasn't so much of an issue, so you don't want stats more than three or four years old.
posted by krisjohn at 4:02 PM on May 18, 2006

Most of the copper they're citing is in the main stepdown transformer in the power supply.
posted by Steven C. Den Beste at 4:45 PM on May 18, 2006

I can't come up with any numbers, but I did just want to say that if you looked inside my PCs you'd see a significant amount of copper used in the heatsinks for the CPU and graphics card. Such products may alter the average amount of copper in a modern PC vs one made back when cooling wasn't so much of an issue, so you don't want stats more than three or four years old.

Enthusiasts often build PCs with copper HSF units, but the stock units are often made of aluminum.
posted by b1tr0t at 4:48 PM on May 18, 2006

Thanks everyone. I would assume that SVTC's number has to include the monitor/CRT.

After I read these answers I did a little digging; if it's true that the average 70lb computer contains 6.9 per cent copper, that beats the copper content of ore extracted at Escondida, the world's biggest copper mine, by a substantial margin:

The combined proven and probable ore reserves of Escondida and Escondida Norte as at 30 June 2004 were: 2 018 million tonnes of copper sulphide ore at 1.24 per cent total copper; 1701 million tonnes of low-grade copper sulphide ore at 0.55 per cent total copper; and 290 million tonnes of copper oxide ore at 0.73 per cent acid soluble copper.

Of course that says nothing about the economies of scale or relative difficulty of extracting copper from copper ore versus PCs. Interesting stuff nonetheless. Thanks again for the answers.
posted by nyterrant at 5:03 PM on May 18, 2006

The power supply has several large inductors as well as the main transformer. CRTs have several large inductors and transformers as well as a degaussing coil, which can be close to a pound itself. Finally, plastic insulated wire often looks silver, but it is copper on the inside (the strands are pre-tinned, there should be another name for that..).

I think your average medium desktop case with 17" monitor would have at most 2 lb of plastic insulated and magnet wire, and less than 1/2 lb of copper in component leads and PCB traces (there is also the stuff inside the actual picture tube?!?). 70lb is actually a good weight estimate, even for 1990s & early 2000s era systems (monitor 17kg, PC 12kg --> 64lb). I guess as cases got lighter monitors got heavier to match. Check out computer weight through time :P

At industrial scale I think they just pulverize the entire PC, without any disassembly. Then they use magnets and air jets and floatation to separate different materials. Probably several stages of pulverizing actually.. coarse grind and then separate plastics and big chunks of metal. Whatever's left needs more grinding before it can be separated. At some point you still have to just melt/burn the thing to get at the copper though. Magnet wire has enamel, while it could be etched off chemically, it is probably easier to just burn it.

The problem at a small scale is that you have to disassemble the outer case, then hack out the good bits, and then you still have to burn off the insulation (enamel or plastic).

There are some parts in PCs that are actually worth recovering as parts. Various connectors, relays, large capacitors, the fast recovery diodes in the power supply maybe.. The problem with that is testing. It is one thing for an individual to hack apart some electronics for his own parts drawer, but if you are going to try and sell it..

All in all, the economics aren't a complete dead end, but there are a lot of challenges to overcome.
posted by Chuckles at 12:03 AM on May 19, 2006

All in all, the economics aren't a complete dead end, but there are a lot of challenges to overcome.

The first part is understated. In places like California, buyers of new electronic equipment pay a surcharge that goes to a state-administered fund, and a recycler earns (at least) his cost of capital on state funds alone. The money made on commodity resale is pure economic profit. If you've got a spare $6 million floating around, opening such a plant would be a great investment.
posted by Kwantsar at 5:00 AM on May 19, 2006