# Induction furnace for PCBs



## kjavanb123 (Sep 4, 2013)

All,

I vidited this guy who is making induction furnaces with a monitor that can change the temprature by one degree plus or minus celcius, while retaining it for as long as one wants. He melted about 0.5 lbs of copper in 5 mins which was pretty cool, it also a big saver on consuming energy.
I have sent him a couple of PCI cards, with components melting points to try to use this induction to separate metals, and plastics.

Any guesses what is the outcome?

Here is the photo of a 30 lb furnace.




Regards,
Kevin


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## g_axelsson (Sep 4, 2013)

A black mess?  

Göran


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## Smack (Sep 4, 2013)

Kevin,
Is he using a CU collector then adding the ground up PCB's to the melt? Or is the material pre-incinerated?


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## Platdigger (Sep 4, 2013)

Is this guy selling these furnaces?


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## rickbb (Sep 4, 2013)

I hope he's got some kind of scrubber smoke stack to deal with the toxic out gassing from melting plastics. :shock:


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## bswartzwelder (Sep 5, 2013)

THAT PICTURE IS A REAL TEASER. At first sight, the green box like thingy appeared to be a pump. After looking at it again, I recognized it as a gear reduction unit that I have had years of experience with. Although it could be used for a very slow rotation, the green box (with the shaft running through a pillow block and into the unit) would seem to be turning something. Could you give us a little more information? If anyone buys one of these and wants to set up their own business, let me know. It may be one of the best alternatives for dealing with scrap e-waste.

After some more study, I saw the chrome plated hand wheel and the fact that the shaft is actually bolted to the side of the furnace with the flange. Now some things are making perfect sense. The ENTIRE furnace rotates. If I am correct, the unit probably weighs a hundred pounds or possibly much more. Turning the hand wheel rotates the entire furnace to facilitate unloading.

Edited after looking at the picture in more detail. Getting old s**ks.


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## kjavanb123 (Sep 5, 2013)

All,

He is selling these units for welding or steel industry, since you can adjust and retain temperatures to a degree celcius, and it can reach to 2800 c, it could be used to produce special alloys.

The green gear reduction is used to tilt and pour the molten metals out.

The unit behind it is the electrical unit to produce the energy to melt.

He has not done anything with PCBs, I sent him a few graphic cards with gold fingers, so not massive smell or toxic, plus I gave him all the components melting points, starting with the epoxy up to any iron used in PCBs.


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## Harold_V (Sep 5, 2013)

bswartzwelder said:


> THAT PICTURE IS A REAL TEASER. At first sight, the green box like thingy appeared to be a pump. After looking at it again, I recognized it as a gear reduction unit that I have had years of experience with. Although it could be used for a very slow rotation, the green box (with the shaft running through a pillow block and into the unit) would seem to be turning something. Could you give us a little more information? If anyone buys one of these and wants to set up their own business, let me know. It may be one of the best alternatives for dealing with scrap e-waste.



Before you make such a decision, you'd be well served to discover the frequency at which the power supply operates. Induction furnaces rely heavily on being the proper frequency, which is determined by the tyoe of material to be melted, and the size of the furnace. If it's large enough, line frequency works, but that would be *far* beyond the size that a home shop could justify. I would suggest that a furnace of the size shown would require no less than 10,000 Hz., and that most likely would not be high enough to melt boards. 

You can circumvent that to some degree by starting with a large mass, but that may not be desirable, as you now have more base metal to eliminate. Most likely would work just fine if the resulting metals were intended for shipment to a copper refinery, however. 



> After some more study, I saw the chrome plated hand wheel and the fact that the shaft is actually bolted to the side of the furnace with the flange. Now some things are making perfect sense. The ENTIRE furnace rotates.


Yes, that's correct, but this guy needs to go back to the books. Tilting furnaces should rotate about the spout, so it discharges in the same location, regardless of the attitude of the box. With his rotating near the center-point of the box, that won't be true. If you were trying to hit a small target, you'd have to keep moving the receiver, which isn't a good idea. 

My tilting reverb. furnace tilted near center, but I poured to large cone molds, so that wasn't a problem. I chose that design as it requires considerably less effort to pour. The typical small sized induction furnace box has hydraulic cylinders to assist in pouring, or a chain fall is used to tilt the box. Because of the pivot point being located at the tip of the pouring spout, they are extremely difficult to tip, as you pick up the entire box. 



> If I am correct, the unit probably weighs a hundred pounds or possibly much more.


I would suggest a lot more. I have a 100 pound furnace, and while I haven't weighed the box, there is little doubt in my mind that it runs closer to 500 pounds. Refractory can be very heavy, especially if the furnace is built such that the charge is in direct contact with the refractory, as many of the induction furnaces are built. Small units are often built around commercial crucibles, but that is not true of larger furnaces.

Harold


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## bswartzwelder (Sep 6, 2013)

Thank you, Harold and kjavanb123. I suspected the rack behind it might be the power supply. If I had a unit that size, I'd have to notify the power company every time I turned it on. Also, while thinking of all the gold on e-scrap, didn't consider the amount of base metals you would be adding to the mix. Just didn't see the forest for the trees.

Almost all microwave ovens (for cooking food) are set to one specific frequency. While I don't remember what it is, I do remember the original designers knew that different foods would require different frequencies. Then, some smart engineer realized that almost everything has water in it. Problem solved. If you are cooking food, the microwave is designed to operate at the optimal frequency for vibrating water molecules. Food with little water doesn't do so well in a microwave. That's why popcorn comes in those little bags which say "cook with this side up". They have something embedded within the plies of the bag which vibrates at almost the same frequency as water producing the heat.

Harold, I would suspect the frequencies of industrial units could even be variable, but I have no experience with them. But, either way, they are out of the reach of the hobbyist refiner. Thank you for the explanation.


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## Geo (Sep 6, 2013)

not sure about all municipalities, but here, if a residential power usage spikes outside of the norm you can expect a visit from the authorities. inside growing operations consumes large amounts of power and is a red flag for law enforcement. it may well make good sense to let the utility know your power usage will be going up and why.


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## bswartzwelder (Sep 6, 2013)

When the Calvert Cliffs Nuclear Power Plant first went online, they were getting their power from a small Co-op. Imagine, when they powered up one 6000 horsepower reactor coolant pump for the first time. The pumps operate at 13,000 volts. They dragged the coop offline shutting down power for everyone. The have four such pumps for each reactor and 2 reactors. Once everything is heated up, the power from each pump drops to 4500 horsepower. By the way, to initially heat up the reactor to operating temperature, all they do is turn on the reactor coolant pumps. The friction of the water through the pumps heats the water to the 400 to 500 degrees F.


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## butcher (Sep 6, 2013)

Ted Williams a member of the forum, has done a lot of experiments making his own induction furnaces, he has a web site with the description plans and schematics to make the induction furnace, I have experience in electronics and have found this very interesting, and hope one day to have enough time to try and make one myself.

http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat1.html


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## kjavanb123 (Sep 6, 2013)

Back to the main topic, if PCBs are shredded, and a good scrubber is in place, using right fluxes, can this furnace be used to melt epoxy then unload, then go after lower melting metals to highest in PCBs?

The guy hasnt received my sample graphic card yet to test, so I will post his result as soon as I have them.

Regards,
Kevin


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## Smack (Sep 6, 2013)

There is no amount of heat that will separate the metals out of circuit boards, not the metals your after anyways, the melting temps are too close together. You can sweat aluminum and solder but those are not what your really after. This is why Dore Bars are made.


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## Harold_V (Sep 7, 2013)

Smack said:


> There is no amount of heat that will separate the metals out of circuit boards, not the metals your after anyways, the melting temps are too close together. You can sweat aluminum and solder but those are not what your really after. This is why Dore Bars are made.


It's far more involved than that. Once alloyed, melting points of individual elements are no longer a consideration, as they change. Beyond that, it's virtually impossible to separate metals by temperature, as molten metals are solvents, so they dissolve other metals, even though they may melt at much higher temperatures. 

With precious few exceptions, you can rule out separating metals by melting or stratification. Because some metals prefer the company of other metals, you can separate gold from iron by melting with added silver. Silver tends to not form an alloy with iron, so it readily picks up the gold, separating the iron from the mix. I know of no other examples, but I'm sure there are a few. 

Harold


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## g_axelsson (Sep 8, 2013)

Harold_V said:


> Silver tends to not form an alloy with iron, so it readily picks up the gold, separating the iron from the mix. I know of no other examples, but I'm sure there are a few.


A classical one is when zinc robs silver from lead and separates in a zinc-silver phase and a silver free lead phase.
http://en.wikipedia.org/wiki/Parkes_process

The gold-silver-iron system was a new one for me. Thanks!

Göran


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## kjavanb123 (Oct 2, 2013)

All,

I finally got a chance to test smelting the PCBs with the furnace maker, and here are the result, 

I used Cryolite and some borax and broke a piece of memory RAM, 5 minutes into the furnace it was melting, because of Cryolite in the flux indeed part of graphite furnace is also removed,

Here are the metal beads inside the slag from melting a memory stick,



Here is the slag and metal after cooling the furnace from smelting a memory stick,



So I did roughly 200 grams of mixed cards, also with more borax and less Cryolite, then melted the resulting metal beads to form the following,



This is the slag from the above process,



I will post XRF result on both slag and Dore metals in a few days, cool thing about induction furnace is it takes a very short time to smelt.

Regards,
Kevin


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## kjavanb123 (Oct 20, 2013)

All,

After reading the NoIdea post on pyrolysis and how he dealt with smokes, since I am using induction furnace to smelt, the smoke can be directed to an old heated with charcoals, the pipe enters the bottom of the heater with the charcoals fired up, then the produced smoke will be directed to water buckets, then exit through the hood. I am going to try this on a small scale to see if it works or not.

Regards,
Kevin


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