tonyd said:
Harold if you have any ideas on building a furnace to melt the aluminium, I would appreciate your thoughts and ideas, what size mould would you suggest.
I'd suggest you size it in keeping with the volume you expect to process at any one time. Too large can be a negative in that it isn't easy to use a small portion of a large ingot, while small ones can be added with little effort. At some point, the ingots you sell will be re-melted---so you want to insure that they aren't too large. Don't have a clue what size that may be, however. If I had to venture a guess, I'd say keep the ingots smaller than 5" wide and 12" long.
If you have a salvage yard in mind where you intend to sell your aluminum when you have enough, it might pay you to inquire of them if there is a penalty for melting. You may be surprised to find it is worth more before melting than after, although I don't know that. Just trying to insure you don't go to a lot of work and lose on the proposition.
Depending on the volume you melt, the ingots you create may not be attractive. Considering they'll pour on a low volume, but continual basis, I expect you'll have some cold shuts, but that shouldn't affect their value. Starting with the mold well preheated would help in that regard.
As far as the furnace goes, I think my advice would be to size it in keeping with the size of items you intend to melt. The smaller, the less expensive it would be to build and operate, and it would yield a correspondingly smaller amount of aluminum. My thoughts would run towards an interior diameter of roughly 12", or slightly larger. It need not be very deep----and should be formed such that there is a low side, inside, where the discharge is located. Sadly, I do not recall the size of the one I mentioned, but it was not very big. Less than 4' tall, and less than 3' diameter on the OD. He ran his without a lid.
There are a number of burner designs on the market that run without a blower (propane), but if you intend to use waste oil, you may have to design one on your own. The oil can be sprayed though a nozzle, but unless it's well filtered, and the pressure is quite high, it may not perform well. Unfiltered oil will clog the nozzle easily, and often.
If you have compressed air at your disposal, you may be able to use air pressure to atomize the oil-----I understand there is such a design on the commercial market. I am not familiar with its operation.
I would suggest the port for the burner be located slightly above the bottom, tangent to the inside diameter. It would be desirable for the flame to swirl around the lining. Once heated, the lining will melt newly introduced aluminum quite quickly.
You can expect a reasonable amount of dross, which has value as well, although you may not find a ready market. It contains a substantial amount of oxidized aluminum. If it is returned to major aluminum refiners, it is once again reduced to aluminum via arc furnaces.
The furnace could be made of a castable refractory, or rammed, using a rammable refractory. Casting might be easier. Both methods would require an inside form, plus one for the burner port. The furnace may not require a lid, although it would be more efficient with one. One that swings away easily (on a pin that is fastened to the exterior housing) might be the solution. The furnace could be poured (or rammed) in a large steel barrel. Here in the States one might choose a 55 gallon drum, or one slightly smaller. They are easily cut to length with a torch, or even cut with an abrasive saw.
I, too, have an interest in an oil fired furnace, although mine would be intended for melting bronze and brass, using a crucible. The design would be similar, regardless of the application. I'd appreciate hearing from you with anything you may discover in that regard. I'll keep you in mind if I uncover anything of interest.
Sorry I'm not more help.
Harold
