Harvesting Copper from Microwave Ovens

Obsolete appliances were once a gold mine of parts, free for the taking with a few snips of your diagonal cutters. Times have changed, though, and most devices yield only a paltry supply of parts, so much so that only by harvesting raw materials can you get much value out of them. And so we have this example of reclaiming copper from used microwave ovens.

The primary source of copper in most microwaves is the transformer, which we usually see re-tasked for everything from spot welders to material handling electromagnets. But the transformer is not the only source of the red metal; [eWaste Ben] also harvests it from relay coils and the main coil and shading coils of the fan motor.  The bounty is melted down in an electric foundry and cast in a graphite mold into a lovely ingot.

Unless you’re into repeatedly casting copper trinkets, a large bar of reclaimed copper might not be something you have a burning need to possess. But bearing in mind that copper can go for about $2.50 a pound at the scrap yard, there’s some money to be made, especially with dead microwaves essentially free for the taking. As [Ben] points out, taking the extra step to melt and cast the copper harvested from microwaves makes no sense if all you’re going to do is sell the scrap, but it’s nice to know how to do it just the same.

55 thoughts on “Harvesting Copper from Microwave Ovens

      1. I don’t think so, a waveguide made of copper would drive the cost way up on microwave ovens.
        They are made from aluminium (or even steel I bet).
        In fact even professional very costly microwave stuff like communication equipment and army stuff uses aluminium, and tests have shown aluminium is equal to copper in results.

        1. No, all magnetrons are made of copper (the cavities) and there is almost as much copper than in the old 50Hz or 60Hz transformers. Now they use flyback transformers operating at much higher frequency to save on weight and copper.

    1. could you get in trouble for that? like.. setup a bunch of magnetrons in the entryway of your house or hidden under the steering wheel of your car aimed at the crotchular area as part of a silent alarm/anti-theft device? when functioning properly, it would be perfectly safe as long as you’re not a thief breaking in, no? just put a “Warning: Risk of Harmful Radiation Exposure” sign on the door.

      not that I wanna risk the one time I forget my keys or an emergency responder has to bust down my door. but, could you get in trouble for that?

      1. Yes you would get in trouble and go to jail or a institution, if alone because you break FCC regulation and cook your neighbors and interfere with RADAR and air traffic stuff meaning you are in fact committing a federal crime or crimes even (if in the US).

    1. You’re telling HaD readers? Ha, preaching to the choir.
      But how many spot welders and spark generators do you need? At some point you might just reach a saturation point.

  1. You can find used microwaves in recycling bins scattered around the city. Often, only the fuse has blown, or the door open microswitch is broken. Repairing is easy and cheap. You can donate the working unit to a local woman’s shelter for abused mothers. They will appreciate it.

  2. Removing the secondary yields lots of copper, and yes you can use the gutted transformer for most of the above purposes. I found that the relays and motors can be scavenged for fine wire as the heat normally debonds any glue originally used.

  3. The magitron tube end is made out of some ceramic with an exotic element and when broken is toxic and thus microwaves are as hard to get rid of as tyres. Careful with that axe! What about the food?

        1. Correction out of fairness: I understand the suits against Johnson & Johnson relate to stuff from the late 60’s up to 1970 or so, and are probably not completely realistic in their claims in regards to the effects.
          So don’t panic yet.

    1. Yes, Beryllium oxide can make you sick, IF You crush it into a powder and inhale it. However most modern microwave ovens will likely NOT have a magnetron with Beryllium oxide but with Aluminum oxide instead and Aluminum Oxide is something very common and all around us. Beryllium Oxide was used because it was better at dissipating heat. Therefore it’s likely only used in higher power magnetrons like those used in RADAR systems. Perhaps some of the older microwaves have these, but my understanding is that most newer ones do not. Also even if it does have Beryllium oxide, unless you shatter it or crush it and inhale the dust, you should not have any worries. However,if yo do find a magnetron with Beryllium oxide, don’t crush it and snort it like coke or else you might get sick. ;)

      1. I remember long ago about a small electronic part in common use which was highly poisonous when broken. I can’t recall what it was though, some diode maybe?
        My habit is to simply not crush and inhale any electronic parts.. more than once a fortnight.

  4. Here in my neck of the woods, all trashed white goods and electronics are recycled on an industrial scale. Which is a very good thing but it does make it almost impossible for the individual to find anything worth scrapping.

    1. Not sure where your neck of the woods is, but if you’re in an area that’s covered by it (here in the US, not sure where else), try CraigsList. They even have a “free” section that has typically has a plethora of things available for only the cost of transportation. Worth a look, anyway.

    2. In the EU it is also common to recycle electronics, but the issue is that sometimes it’s very pesky to actually get them to collect it since you often have to actually bring it to some out-of-the-way collection spot yourself, causing people to toss them out anyway and trust that the city cleaners will pick up the slack as it were.
      But for washing machines and such the shops just take away the old one when they deliver a new one in my area, which is handy for such large items.

      1. in Greece for better or worse we have a caste of people that roams the streets in small trucks and picks up the white goods and scrap metal found on the side of streets and sell them to scrap yards. On occasion i do manage to outrun them and find something useful, like a brand new flood light, an esentially new baby stroller, a powerwheels jeep etc :))

    1. That’s right, what I do is chisel the wire before going thru busting the welds, Al is white, Cu is reddish.
      busting the welds to remove the core is time consuming, and a complete XFMR sells as-is

        1. Aluminum wire is often ‘CCA’ or in other words Copper Clad Aluminium., says CCA on cables that use that. And of course bare aluminium is not solderable so in that sense the copper cladding is a plus.

          No wonder they fail though eh, aluminium wire is so fragile. And has poor HF qualities I hear, since network cables with it are so poor that the US outlawed them when the Chinese stuff caused so many networks to suffer I read.
          And in Britain after a WW2 copper shortage caused many phone lines to historically be aluminium wire, they then found years later that their ADSL was poor because of it. Unexpected consequences.

  5. by melting into bars you may be able to scrap for #1 where as the bare wire goes as #2.

    as #1 you may get more money and if you have a wire extruding machine you could make it bare bright witch gets more money

  6. There’s a lot of money in that scrap that you turned into a raw product.. Given the right mold and shape or just a copy of an ancient armor from the bronze age will fetch you a lot of $$$. I was once a reseller of copper bracelets (for charms) and other alloys like brass and bronze that was made into ornaments.

    1. While I’m not into costume jewellery, so I don’t have a clue as to the value of newly manufactured from salvaged metal trinkets. As where I don’t see many wearing such items in my area, I have to guess they aren’t popular here and so decedent pocket change wouldn’t be made.

  7. Interesting idea. Or you could use a less-broken microwave and some greedbay SiC powder + some random odds to melt copper wire from the really broken units and extrude into ingots. Free copper, and unlike Li-Po packs fewer hazchems to dispose of. (best done outside, and don’t use less-broken MW for food ever again!)

  8. I’d like to point out that it takes a *very* large hole in the ground to mine copper today. We’ve already stripped the surface of the earth of readily accessible minerals and fossil fuels. What’s left requires enormous resources both human and financial to recover. In the early 20th century copper porphyry tenors were 1-2% copper. If one assumes that the tenor is 1% by weight, that means that 100 lbs of rock must be crushed to a fine powder to get 1 lb of copper. It takes a lot of energy to crush the rock that fine.

    I studied geology with the intent of going into mining, but when I finished my MS all the North American metals mines were closed with the possible exception of the iron-nickel complex at Sudbury. And they’d started taking mining staff hostage in South America which didn’t seem an attractive proposition. So I went in to the oil industry as a geophysicist.

    It distresses me greatly to see important resources like copper and aluminum consigned to landfills by ignorant and lazy people. And petroleum wasted by SUVs and hypocrites like Al Gore.

    Of course, no reason to pay any attention to me. I was obviously bought off by big oil and am an anthropogenic climate change denier that should be incarcerated.

    The “consensus” claimed by the fear mongers is like the Bolshevik “majority”, purely fictional.

    1. What is your position on preparations for non-anthropogenic climate change?
      The answer will determine if you’re a partisan assbag or someone who genuinely questions the science. Many people say “The climate is changing, it’s always been changing, we’re nothing to do with it”. When asked whether we should do something about it though, they tend to get defensive.

      Saying that the climate is changing but that we shouldn’t address it because we didn’t cause it is like sitting happily in a burning house, safe in the knowledge that an accidental electrical fault caused it and refusing to leave since it wasn’t arson.

    2. I was about to post a detail comment when I realized I could sum you up with the ignorant reference to a Bolshevik majority. My life sustenance has depended on and always will depend on petroleum production, and I have no reason to bad mouth the industry, but I have always kept my eyes wide open. I have a question for you; do you understand you are working in an industry that has no problem working with tyrants if there is more money to made doing so?An industry that by ignoring the simple science staring them in the face irreverabling detryed property of others. Some years ago there was this chant “dilution is the solution to pollution, and man can’t possibly adversely affect the planet”. The scientists where ignored, what was the result? The oceans had become polluted to the point, that traditional food sources for many cultures, have been poisoned.

  9. While a nice shiny brick is easier to transport than a truck-load of bare wire, I’d be surprised if a scrap yard gave the same price as they can’t verify the purity of your block.

  10. Having a block of copper like that would be more valuable to me than the price I’d get for it at the scrap yard. Something like that would be great to put through a mill and make a custom water block or something. What would be cool is to use a microwave furnace to melt the metal recycled from another microwave.

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