Furnace requirements

what does 'do' mean ?

Dr. K

On Thu, 11 Dec 2003 18:58:59 -0600, "William Kaukler" carved in granite...

I am into small scale reclamation. My thoughts are to remelt the stuff for my own uses. A 5 gallon bucket full of broken glass beer bottles would be far more useable in a remelted form, for example. Same with aluminum. Though I must confess that steel itself is unrealistic, so please remove that from the specs. Carl

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A five gallon bucket of glass would require a bigger furnace than you might imagine. Another interesting point is that recycling glass is more expensive than making it the first time. That is why few places take glass for recycling. Aluminum is relatively easy to melt. The effort to make a furnace for glass or steel will be an order of magnitude greater for aluminum. The path you decide to take starts with heat source and atmosphere control. Gas or electric? Charcoal or oil? Inert gas or reducing? How much material will be melted at once? How often to operate the furnace? They wear out too. Be prepared to rebuild it after a couple of dozen uses unless quality, expensive materials are used. Some web sites exist describing furnace construction. Dr. K

I have built a number of propane fired furnaces that use a blower. There is a fellow selling a naturally aspirated unit all the time an ebay for a couple hundred bucks. You can build the same unit for about half that if your time is cheap.

On Sat, 03 Jan 2004 14:35:30 GMT, "Alan Black" carved in granite...

Got any pics or plans? Carl

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Ron's site shows how to make one. There are many versions there. Buy one or make one. Some (like mine) are without a fan but doesn't need one.

Mart> I have built a number of propane fired furnaces that use a blower. There is

why?

do the math for the energy necessary to melt this stuff. if your plan is just to recycle, do the earth a favor and /don't/ burn even more irreplacable fossil fuel "recovering" material than will ever be saved.

as wk says, recovering glass is an an absolute negative. recovering al & fe is best left to those with economies of scale.

jb

Coalbunny wrote:

On Sun, 04 Jan 2004 05:52:24 GMT, "Martin H. Eastburn" carved in granite...

Thanks Martin! Carl

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Recycling Aluminum is not as simple as it sounds either - that is unless you know what you are recycling. Scrap Al comes in many flavours and many different alloys. While it is easy to melt it is tough to keep clean because of it's affinity for oxygen. You can turn clean scrap into a mix of oxide and aluminum (dross) relatively easily if you are not careful. This can lead to high metal losses and may create an unstable mess that is both dangerous and unfriendly to the environment. Especially if you remelt something like pop cans since they have a very high surface to volume ratio.

Safety issues arise as well: charging wet scrap (say a crushed pop can with a bit of moisture left in it) into a liquid heal in a furnace can, because of aluminums high reactivity and the fact that aluminum oxide is more stable than hydrogen oxide (water), cause a very powerful explosion.

The Aluminum Association has many publications on this topic through their website:

Organizations like the American Foundry Society also publish books and give courses on melting and handling Aluminum. See

You might make a better profit collecting and selling the scrap to existing companies that specialize in this sort of thing. As jb says, economies of scale really matter in this business. See the following for an example: