Insulating a scrap melting pot

[kevin c]

I'm trying not to waste propane, and while my first mods have helped, I'm thinking an insulated sleeve around the pot itself will help a lot more.

So far I have used wind breaks around the open base of the Bayou double jet burner rig I use, and a sheet metal cylindrical sleeve that fits loosely around the propane tank pot I got from D Crockett. During heating the lid of a Harbor freight 12" Dutch oven covers the pot with a near perfect fit. The top edge of the sleeve is bent in close to the sides of the pot, both to trap more heat and also to give a little clearance to the pot's edge allowing me to use vice grips to lift and pour out the remaining melt after ladling out ingots. This set up takes a third to a half of a full twenty pound tank to melt 200 pounds of alloy starting from cold scrap, on the lower side if I get impatient and blast the top of the uncovered scrap pile with a weed burner run off a second tank (and I don't know how much propane the weed burner is using).

I'm figuring to sandwich mineral wool or ceramic wool (the latter is more expensive but is rated to 2400 degrees) between the current sleeve and another smaller diameter sleeve inside it. I have near zero sheet metal working skills but can probably manage a few bends and crimps like I did for the first sleeve by way of holding things together. Cost will be forty or so bucks. I figure on melting/ingotting/alloying 3000 to 5000 pounds a year.

So, is this worth the dollars and the effort? Any recommendations on whether the fancy ceramic insulation is the better choice? Are there ways of reducing exposure to the airborne fibers from the material during sleeve construction and actual use in melting (all sorts of warnings posted in forums on use of this stuff, partly on consumption which is not an issue, and on inhalation, which is).

Thanks in advance.

[guywitha3006]

Go with the ceramic insulation...I have a propane tank pot from the Vendor Sponsor D Crocket. I can melt several hundred pounds at once from cold in 15-20 minutes. I have a 50K btu burner and the regulator is no where near wide open. Last time I smelted (probably mid 40s outside) I did 3 or 4 full batches in a few hours and my 20# propane tank hardly had a dent. I have a stand that the burner sits below flush and then the pot rest on supports. I have the insulation wrapped (1 1" layer) inside the windscreen and the pot snugged inside of that.

[kevin c]

Thanks for your comments! Any issues with fibers coming off the insulation?

[guywitha3006]

I used gloves and long sleeves when I first cut it and placed it, once it was in place I don't really have to touch it anymore. Taking the pot in and out doesn't seem to disturb it enough to be an issue.

[shortlegs]

Insulate like "guywitha3006" with small gap- maybe no more than 1/4" and heat "rubs" sides of pot ,as it rises out of top, extracting more heat. Put lid on top of pot to hold heat in pot. That will be pretty efficient.

[Hossfly]

That ceramic insulation is bad stuff. You need a good dust mask not to inhale it. Very fine particals not asbestos but will make you caugh the rest of your life. Once in place its fine, we’ve used it in the boilers for a lot of years very good, stays where you put it if captured well enough. Just when handling wear that mask.

[Idz]

I just placed about 2" of unbacked fiberglass insulation in a 30 gal drum (18" diameter) and put a 14" diameter sheet metal liner on the inside. My propane-tank pot sits inside on some bricks with a HF burner underneath it. A trash can lid sits on top which is adjusted for draft. This setup has smelted about 2 tons of range scrap and still works fine. In operation the drum exterior is just warm to the touch. I think ceramic insulation is a bit of overkill for a lead smelter.

[kevin c]

Hmm. The problem is that I doubt that I can really seal off the ceramic in the sheath well enough to avoid getting any shed fibers into the air outside the sheath during routine handling (the equipment does not have a permanent set up or location; it has to be broken down and moved for storage when not in use). Wearing a mask during construction is easy enough, but trying to remember to put a mask on AFTER having worn a face shield, arm protectors, gloves and apron for a multi hour melt may be more than I'll be able or willing to do.

Idz, is the fiberglass you used the pink stuff like house insulation? I thought that stuff wouldn't bear the heat. I thought actual rock or mineral wool was needed.

[MrWolf]

Not quite as insulating as what you are looking for but I converted a weber grill into a smelting station. I use a welding blanket as my wind shield. No where near as what you are looking to do but just another thought. Good luck.

[kevin c]

Update: I ended up using two inches of pink fiberglass insulation wrapped in heavy duty aluminum foil and sandwiched in sheet metal. It works pretty well; I estimate that I can melt 200 pounds on a quarter tank or less.

One problem with not using the high temperature stuff: I actually have burned/melted away some of both the foil and the fiberglass while playing the weed burner over the top of the melt. Oops.

[durango]

Kevin: If you are burning a third to half a 20

















Kevin: If you are burning a third to half of a 20 lb. tank to melt 200 Lbs. of lead you need to check your burner/tank. Are you buying those short filled tanks (15 lbs.) at the grocery stores? Is your burner too small? My burner is not all that big and I get my tanks filled to 20 lbs. at the local propane dealer for $15.00 and my propane use is so negligible that I can't tell you exactly how much I use but I'm guessing I can easily melt over a 1000 lbs. per tank. I use a HF Dutch oven and can melt over 100 lbs. in 15-20 minutes. Something is wrong somewhere and instead of spending time and money on all the shields and nasty/toxic insulation, I'm thinking you can find your 'money leak' elsewhere.

Just my 2 cents, FWIW. Steve

[Springfield]

Make sure you have a hi pressure regulator, otherwise it takes all day to melt stuff. A regular BBQ regulator won't work well.

[Idz]

In my insulated furnace my last smelting of scrap yielded about 200 lbs of ingots, 100 lbs of debris, and used about 3 lbs of propane. Its not a good idea to play the weed burner directly on the melt. You'll vaporize lead with the high temperature flame.

[Ramson222]

Ive been thinking a lot about how to go about insulating my big bottom pour pot. The best and least expensive idea seems to be perlite a type of volcanic glass used in gardening. Perlite is used to insulate forges and has a melting temp of 1600f your scrap melting pot will never see such temps. Here is a link to the product, note that the description includes insulating and incombustible https://www.farmstore.com/product/supreme-coarse-perlite-2-cu-ft/

[Dragonheart]

All you need is a skirt around the pot to catch & hold the heat.227944

[kevin c]

My skirt wasn't integral to the pot like yours, dragon heart, but unfortunately I don't have mad fab skills. Tin snips, a cordless drill and pop rivets are as close as I get.

I use the Bayou double jet burner, which has plenty of BTUs, but I did have to clean the orifices when I started getting yellow flame out of one jet, and also had to replace the high pressure regulator when it pooped out on me. Maybe those repairs account for the improvement to melting 250# on roughly a quarter tank, in line with what you all describing, but it seems to me that the flame color and gas flow are just back to where they were before, back when I had to use a lot more fuel per melt.

I'd heard of the potential for vaporizing lead with high temp torches used for welding or cutting, but hadn't thought a propane only set up would get in the same range.

Perlite, huh? Let me know how that goes, in case I want to try something other than Fiberglas.

[Dragonheart]

Kevin, I understand, so if I were you I would take a length relatively easy to bend sheetmetal like roof flashing and form a circle about an inch in diameter larger than my pot and rivet the ends together. Then with my tin snips I would make a series of shallow cuts around the top of the circle of sheetmetal and fold down the resulting tabs so they were as snug as possible at the top of the pot. Basically making a similar, but none welded skirt like mine just held in place by sitting on the burner's support and a friction fit at the top of the pot. What you want is to hold the heat against the pot and a skirt will do that.

As far as a regulator I don't use one, just a valve that I use to adjust the gas flow.

The danger of melting lead does not come from vaporizing the lead. It comes from lead molecules bonding to the vapors coming off the pot from whatever is cooking off out of the scrap. The content of these vapors may be even more harmful than the lead. I personally wear a full face respirator when I process my range lead, relying on the wind to blow the vapors in the other direction in my opinion is foolhardy. Just because you breath out doesn't mean what you breathed in is gone! BTW: I am a Federal & State Certified Lead Risk Assessor.

[kevin c]

Well, there's nothing like talking to an actual professional in the field to get good information and advice based experience and well considered opinion. A respirator it is. Any recommendations on the cartridge?

[Dragonheart]

Well, there's nothing like talking to an actual professional in the field to get good information and advice based experience and well considered opinion. A respirator it is. Any recommendations on the cartridge?

I have always personally used and purchased North Brand respirators for my crews. We used a combination HEPA/Vapor cartridge. With a properly fitted respirator you should be well protected. Not to minimize any exposure, but the big danger is for developing children especially under age 6. Make sure the pets & especially children stay well away from your work area. Wash up good before you eat or drink and realize you and your clothing may be contaminated so no hugs for the kids until you are clean. Lead can also get tracked into clean areas so be especially careful if you have small children, especially rug rats that can pick up lead off flooring.

[kevin c]

Thank you!

[kevin c]

This is what I ended up with.
228451
There is one of DCrockett's half propane tank pots inside that sleeve, which, as I described above, has a couple batts of pink Fiberglas wrapped in foil and sandwiched in sheet metal. Seems to work fine.