Thinking of a small-scale incinerator for pyrolyzing ICs

[Beirdo]

I am amassing a fairly sizable collection of ICs as I strip boards, and I'm coming to the point where I'm starting to think seriously about how to incinerate them. I have a concept, which I will describe momentarily, but, as always, it comes with questions.

My concept:

I want to do relatively "small" batches... So I was thinking of using a charcoal chimney starter, and to put the ICs into a tin can with holes punched in it, and put another slightly larger tin can over the top upside-down to form a lid. If I put that into the chimney, then filled it up to the top with charcoal then ignite...

Questions:
1) will this get hot enough to do the job, or would I need to add a fan below the chimney to add oxygen to heat it more?
2) should I instead use 2 chimneys stacked, and put the can of ICs in the middle so there's significant fuel below them?
3) how long does a proper incineration/pyrolyzation take? I'm wondering if I'd have to refill a time or two.

Any comments?

 

[trashmaster]

Check out post here on GRF for a member named Noidea he is is pretty much the house expert on this .

hope this helps.

P.S. He also has many vidoes on here.

 

[patnor1011]

I am using regular hard coal. It gives out more heat and last longer. In that way I can do more batches in one fire. I get that in 20kg bags. That will last me to about 3 "sessions" where I have no problem to pyrolyse/incinerate about 3-4 kilograms of IC chips every session. I do them in half a kilo batches each takes about 10-15 minutes. I put container with chips inside on red hot coal and cover sides up to the top with red hot coal. Chips are red hot in no time and when taken out they are grey/white and can be easily crumbled in fingers. (after they cool of course)

 

[Geo]

i can tell you about a failed attempt i made and what happened. i used a metal can with a metal top that you push on (holiday popcorn can) about half the size of a five gallon bucket. i drilled a couple dozen 3/8" holes in the bottom and cut a 4"hole in the top. i used a holiday cookie tin to hold the IC's. the tin was 8" diameter and 2.5" tall with a metal push on top.in this a drilled 1/4" holes over the entire surface (bottom,sides,top). i set the large can on a grate and filled 3/4 full of charcoal briquettes. i placed the IC's in the smaller can till it was full and put the top on and placed on top of the charcoal. i added charcoal around the smaller can to within a couple of inches of the top. i placed the top on the large can and lit the charcoal from the bottom with a propane torch. in a couple of hours i had a nice flame coming from the hole in the top of the can. i let it burn completely out and just knew i got a good burn on the IC's. it burned the paint from the large can so i know it was at least a dull red all over.when it cooled i removed the smaller can and opened it and dumped the chips in a pan. there was a core in the middle of the can that was still black. they were easy to crush but still had a lot of carbon in them. the outer couple of inches were chalky white. ive decided to modify the large can. instead of many small holes, ill cut a 2" hole in the side at the bottom and add a small 2" steel pipe with a CPU fan duct taped to the end blowing air into the can. hopefully i can get the air/fuel mixture to the point i can keep it bright red but not melt either can.

 

[Beirdo]

Geo: that sounds rather similar to what I was thinking of. I think the main difference (which may actually be a crucial one in the end: I hope to use a can to hold the ICs that is taller and smaller diameter. That may have been part of the failure of the can you had... being to short and wide.

Anyways, it will likely be next weekend at the earliest when I'll have time to go to Lowes to get a charcoal chimney and fuel... I'm thinking of using chunk charcoal for now (as it's easy to get, and I think I like it better than briquettes). Maybe I'll compromise and use briquettes... I dunno. I have to check up on the roof of the apartment building to see if they have a charcoal BBQ for me to set this on, or if I'll need to buy a cheap one of those too. I know they have gas BBQs, but that gives me no excuse to be up on the roof messing with a charcoal chimney starter either.

I really need a house... and a yard... and a shed that I can outfit with a fume hood... Hopefully soonish.

 

[NoIdea]

Check out post here on GRF for a member named Noidea he is is pretty much the house expert on this .

P.S. He also has many vidoes on here.

Thanks Trashmaster, only pictures no videos, though, one day maybe.

Beirdo: Volume to surface area plays a big part in the success of pyrolysis, as pyrolysis starts from the outside surface and work inwards, the problem arises when the volume gets to large and the charcoal left after pyrolysis creats an insulation barrier making it harder for heat to completely reach the center. You can compensate by putting bits of iron inside horizontally layered from top to bottom.

If any air enters the can and you find white/grey ash inside, then you are introducing incineration, which could cause the loss of values.

If i perform pyrolysis in the backyard fire, using two cans, one inside the other, as described earlier without the extra holes, i always make sure the exit gases go through an ash bed, on which the cans sits with the fire build around it, any halogenated gases(Cl, Br, and Fl) produce should (hopefully) react very quickly with the alkali ash.

Hope i havn't rabbited on too much :lol:

Have fun

Deano

 

[Oz]

I have to check up on the roof of the apartment building to see if they have a charcoal BBQ for me to set this on, or if I'll need to buy a cheap one of those too. I know they have gas BBQs, but that gives me no excuse to be up on the roof messing with a charcoal chimney starter either.

I really need a house... and a yard... and a shed that I can outfit with a fume hood... Hopefully soonish.

Do not do this on or about any grill surfaces that may be used for cooking food at a later date. Electronics have many toxic substances in them. There is no need to poison the neighbors or have them consume cancer causing substances.

 

[Beirdo]

Do not do this on or about any grill surfaces that may be used for cooking food at a later date. Electronics have many toxic substances in them. There is no need to poison the neighbors or have them consume cancer causing substances.

Yeah, my plan was actually to get my own small grill for this express purpose... but it turns out that the owners of this fine establishment have decided that charcoal grills are a fire hazard... and gas grills are not. Their logic escapes me. I do live right next to a city park, but I don't think they allow you to bring your own grill either, and as you mention, doing this on top of their grill may be very unwise for the very reasons you state.

I so need a back yard! Anyways, I have my container of ICs more than half full with all the RAM sticks and other circuit boards I've stripped, but I guess I get to hold off on processing them a bit longer while I find an appropriate place to make em real hot... If anyone's in the Seattle area and wants to share the adventure, I'm all ears at this point. Heh.

Meanwhile I have more boards to strip, etc, and I guess at worst, I can always sell the ICs either on eBay or to boardsort.

 

[Beirdo]

Beirdo: Volume to surface area plays a big part in the success of pyrolysis, as pyrolysis starts from the outside surface and work inwards, the problem arises when the volume gets to large and the charcoal left after pyrolysis creats an insulation barrier making it harder for heat to completely reach the center. You can compensate by putting bits of iron inside horizontally layered from top to bottom.

Ah, OK. So I would estimate that a taller thinner can would be better than wider squatter one. makes sense to me.

If any air enters the can and you find white/grey ash inside, then you are introducing incineration, which could cause the loss of values.

If i perform pyrolysis in the backyard fire, using two cans, one inside the other, as described earlier without the extra holes, i always make sure the exit gases go through an ash bed, on which the cans sits with the fire build around it, any halogenated gases(Cl, Br, and Fl) produce should (hopefully) react very quickly with the alkali ash.

Ahh, OK, so nix the holes in the cans completely, or just put a few around the top of the inner can to allow the gasses to escape that can into the inverted covering can, which then put holes on the bottom so the gas is routed out through the ashes that accumulate from the burning fuel? Is that the general trick? If I could draw, I'd sketch up what I mean if it's not obvious, but I suck at drawing.

Of course, I'm still gonna need to find somewhere where I won't get evicted or arrested for burning charcoal around a can of ICs (or even without the ICs!).

Hope i havn't rabbited on too much :lol:

Oh no, rabbiting on is fine by me. There's always parts of the picture I haven't thought of yet. Having someone around who's learned some of the lessons already saves me learning it all the hard way. Thank you for spreading your knowledge

 

[hyrdr]

New here and looking for this same process. I know this is a older thread and reading it again for most wont happen but. It give me thoughts.

Could one incinerate these chips in a small stainless pot or pan in top of hot coals from a recreational fire? I have seen aluminum cans and glass melt on good coals. I have also won money camp side betting I could boil water in a paper cup on these coals.

Is more heat is required a leaf blower real low pointed at the coal bed really produces a lot of heat

 

[FrugalRefiner]

hyrdr,

Heating IC chips in the open air will release all sorts of nasty, toxic vapors into the atmosphere, poisoning us all.

Pyrolysis is the first step in treating these chips. That means heating them in an oxygen starved atmosphere to drive off the volatile gasses, and burning those gasses in the process of combustion. Search for posts by NoIdea (Deano). He has covered this topic very well.

Dave

edited to correct spelling

 

[Marcel]

I do use use a charcoal chimney starter!
I run some small test batches with it. Works great, only causes fumes, because the heat is too low.
But you could also use a hot plate instead, almost same temperature range!

 

[chlaurite]

blue = cheap stainless steel pan
black = black iron pipe, 1"
orange = copper tubing, 3/8"

The snow has finally gone, so I'll give this a try perhaps next weekend, and post my results. As my biggest concern, I have to wonder if thermal expansion will either cause the black iron pipe to crack, or spoil the seal at the bottom of the pan.

Any thoughts?

 

[FrugalRefiner]

Interesting design.

My concern would be the copper tubing. Copper melts at 1,984° F. (1,085° C.). With a good, hot fire, it could fail.

Understand that pyrolysis requires an oxygen starved atmosphere. If you pump air in from the beginning, you're incinerating, not pyrolyzing. Now if you start without any added air to first pyrolize the material, then follow up with air to incinerate the remaining carbonaceous material, you may enjoy some success.

I would still consider replacing the copper.

Dave

 

[chlaurite]

Now if you start without any added air to first pyrolize the material, then follow up with air to incinerate the remaining carbonaceous material, you may enjoy some success.

I had planned to let it "cook" for a few hours, then turn on a trickle of air to oxidize anything left. From related posts on this topic, it sounds like people have very mixed results with pyrolysis alone, which I wondered if a second incineration-proper pass might solve. It seems odd, IMO, that some people end up with nothing but fine greyish-white ash and metals, while others report getting plastic gravel no matter how hot or how long they run it... So after reading various accounts, I hypothesized that air leaking into the container may make the key difference (Patnor's original method didn't even try to starve the container of oxygen, and he got great results).

I took my inspiration primarily from NoIdea's plans, but wanted to add an aerobic stage (and also to come up with something a bit simpler to set up over, say, a backyard campfire rather than a dedicated enclosure).


My concern would be the copper tubing. Copper melts at 1,984° F. (1,085° C.). With a good, hot fire, it could fail.

Good point, I honestly hadn't considered that - Unfortunately, I also can't think of any commonly available, reasonably-flexible metal tubing available to use as a stand-in.

As I understand it, though, we only need to get up to around 500C (roughly in the ballpark of a vigorous wood fire without a blower) to make the smoke relatively harmless? I care more about not poisoning myself than about efficiency here - I have dozens of acres of winter blowdowns I need to burn anyway over the summer, so fuel supply and time don't really present a problem or an expense here.

 

[patnor1011]

Right, air was beneficial in my process as I did not stacked them chips too tight. That is why they burned out so completely. People who report not proper incineration probably tried to incinerate too much of them at once in smaller container.
I am guilty of misusing terms, so in my case what I did was incineration not pyrolysis.

 

[MEANIE]

My concern would be the copper tubing. Copper melts at 1,984° F. (1,085° C.). With a good, hot fire, it could fail.

Good point, I honestly hadn't considered that - Unfortunately, I also can't think of any commonly available, reasonably-flexible metal tubing available to use as a stand-in.


I am new here very new ..so i may be way off base here but could you use a stainless steel flex tubing thats made and used on home gas cook stoves..as the supply line.... just a tought

meanie

 

[Kilroy2k1]

To replace the copper tubing use steel brake line available from places like napa or autozone. you can get it in various diameters and its not too bad to work with unless your trying to make a very tight turn.

Tom.

 

[Geo]

if you do have to make a sharp bend or curve, fill the tube tightly with dry sand.if the sand is tight enough, you can bend the tube without crimping it.

 

[g_axelsson]

blue = cheap stainless steel pan
black = black iron pipe, 1"
orange = copper tubing, 3/8"

The snow has finally gone, so I'll give this a try perhaps next weekend, and post my results. As my biggest concern, I have to wonder if thermal expansion will either cause the black iron pipe to crack, or spoil the seal at the bottom of the pan.

Any thoughts?

I really like your idea but I think it needs some refining...

It will be very hard to empty the pan without digging up the tubing. How about bringing the air pipe in from the side and just use a shorter pipe leading down 10-20 cm. Add a long handle and you can move it around as the fire burns down and empty it without problem. The possibility to shake it could also make it easier to get a complete incineration. It would also allow you to run several batches without waiting for the fire to die out.
I wouldn't be so concerned about the seal between the tubing and the pan, I would worry more about the seal between the lid and the pan. How to solve that easy I don't know.

Göran