am I wasting my time

I'm interested in smelting and casting some Aluminum so I'm cleaning out the backyard and sorting everything that looks aluminum:-)
I found an old "char-boil" gas bbq. The gas burners have long since rusted away but the outside case looks like cast Aluminum. Its light.
Could it be something else? Could it be too oxidized to be usefully for melting?
Does aluminum-oxide just become slag on the top of the melt or does the heat drive the oxygen off and I get aluminum back.
I dont even have the furnace made yet but I'm collecting scrap Al.
Al
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Hi You wont be smelting, thats useing ore :) I melt bbq grills for the alum to cast sundials. you can get about 10 lbs out of a grill. Drive around on trash day, if you want more of them.
Window frames and other extruded forms do not cast as well item that were cast from the factory. But they do cast, just not as well so dont mix the two. Alum for casting has much morte silocon(sp) in it.
Buy a can of flux from budget casting suppy in CA. This willl help a lot to clean the trash out and not lose so much alum during the skiming.
Les

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Thanks for the reply.
snipped-for-privacy@nowhere.net wrote:

It sort-of seems like smelting, with all the crud, old paint and crusty stuff on this BBQ:-)

I'm making two piles in the backyard. I lucked-out at an auction and got about 150lbs of nice clean unused extruded aluminum "things". I hope that stuff works too. I have heard that it make a clean melt but is hard to machine.
Al
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I cast a platter for a potters wheel out of 6061 chips, it machined quite whell for a green casting, it should have sat for a week or so. For parts that need much machining use the bbq grill stuff if you can.
Alum is easy to melt and cast, I find copper scary...30 lbs glowing orange does not leave too much room for error. I have added enough copper to alum to make a brass collored metal. It was tough and not brittle. I have made a copper and alum mix that looked like alum but was hard and brittle as glass, fun stuff to mix and match and see what you get.
Please remember to keep your ingot molds dry, ANY water will make them spit molton metal yes I learned the hard way. I now heat the ingot mold over the kiln opening to well over 212F. I have still gotten copper to spit out of a hot mold, I'mnot sure why, maybe a reaction with rust? Point is a lot of things can happen at elavated temps. Wearing a fullface motercycle helmet is not out of the question. And I am dang glad I did when that blob of copper landed on the face mask :) Be safe and have fun. Les

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Hi PIW,
snipped-for-privacy@nowhere.net wrote:

It sounds like you get the melt hot enough and you are just add other metals. Is that all there is to alloying? At least for playing around.
I'm not really sure of the difference between a mix of metals and an alloy. I'm guessing that a mix is like a marble cake. You can see each metal. Does an alloy have the metals mixed at the molecular level or at the crystal level or something like that?
Al
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Picture what happens when you drop a sugar cube into a cup of hot water. The sugar *dissolves* in the water and every drop of the water has essentially the same amount of sugar in it. Alloys work like that. One metal goes into *solution* with the other metal (or metals). There is no *chemical* reaction, it is a (sometimes very complex) physical reaction at the molecular level.
Now most metals will dissolve in other metals, though the properties of the various alloys formed can vary. But some metals just aren't soluble in some other metals, so they won't alloy. You just get the marble cake mixing. The latter almost always has undesirable properties. You can also cause an alloy's constituents to *precipitate* out and form a marble cake mixture by improper heat treatment.
A good physical chemistry or metallurgy textbook will explain all this in much greater detail. If you're going to play with making your own alloys, or attempt to heat treat anything other than plain carbon steel, it will be worth your time to seek out and read one or more such books.
Gary
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wrote:

Don't play around with molten metal. It's too much trouble to "learn on the job", so find some metallurgy textbooks and do some research before you light the burner. As always, try the S/H bookshops and collect cheap '50s textbooks on metallurgy - it's good information, it's well written, and the factory processes of the '50s translate to today's backyard workshops.
I'd never try casting copper. Too much trouble, and you only end up with a piece of copper. Much better to research bronze formulations and find something that's easier to melt, yet more useful once you've made it. Eutectics are definitely your friend here.
BTW - Anyone know a chemical test for detecting beryllium ? I've a pile of mixed bronze scrap, and I'd like to screen out the BeCu alloys before I heat any of it.
-- Die Gotterspammerung - Junkmail of the Gods
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I answer below.

Always with the dont do talk, sounds like mom.
It's too much trouble to "learn

Duh! :) And what if I like the color of copper? More trouble?, how do you figure that? If you gonna make brass or bronze you add to molten copper.
Much better to research bronze formulations

I cant help much with that, if it is a spring or electrical contact it may have some in it. But I have some tubing that is berylium. If it looks like copper, but is tough as hell, beware.
Les
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snipped-for-privacy@nowhere.net wrote:

I take it berylium is a bad thing for the backyard melting. Al
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It makes arsenic look downright friendly by comparison, for people who are sensitive to it. Some people, not everyone, have a very strong, almost allergic, reaction to beryllium. A very small exposure can kill you, or permanently disable you, if you are sensitive to it. The problem is, you won't know you're sensitive to it until it is too late. So the prudent thing is to avoid contact with any particulates containing beryllium.
Gary
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Not to mention cutting, grinding, polishing, machining, or anything else that would provide the opportunity for BeCu to get into you by any means.
--
Cats, Coffee, Chocolate...vices to live by

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Ecnerwal wrote:

wow, now I get it. Now I see why you need a test for berylium. What kind of metal alloy has berylium in it. What are the common reasons that this additive is used? Al
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wrote:

Changes the mechanical properties of bronze and copper, which are a bit soft otherwise. If you find a copper-coloured spring contact in a relay, chances are that it's BeCu. Non-sparking explosion-proof tools (used in petrochemical plants) must avoid steel, but they need some surface hardness if they're to work - so they're usually a beryllium bronze. I've some 1/4" beryllium copper strip in my desk here - when I get round to it, it's to replace the spring mount of the scabbard lock on an Japanese sword. I'll be soft-soldering it though, not using a torch to silver solder it.
Like most cuprous alloys, they're resistant to most corrosion but are susceptible to acid or saline solutions. So it's often safe to handle them with unbroken skin, but a cut or a splinter can suddenly become a hazard.
Beryllium oxide (beryllia) is an insulator with good UHF dielectric properties, so it has been used as an insulator in radio power transistors. The ceramic version is hard and machinable, so is used to make nuts and bolts, where these must be ceramic for heat or chemical resistant reasons. As a solid it's quite stable, but the dust is very toxic.
-- Die Gotterspammerung - Junkmail of the Gods
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Andy Dingley wrote:

So it sounds like for most common scrap copper stuff one might find, pipe, pot and pans, random sheet laying in the street from flashing a house etc the chances of it having beryllium is very low. Just dont go trying to melt the small stuff out of relays or small springs etc.
Thanks for the info. Al
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wrote:

One of the few things worse is beryllium oxide. I'll happily work beryllium bronzes cold (with care), but there's no way I'd heat them. Lots of people just won't touch the stuff.
-- Die Gotterspammerung - Junkmail of the Gods
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On Tue, 21 Oct 2003 13:19:07 GMT, snipped-for-privacy@nowhere.net wrote:

Damn, that always was my problem.
Hey ! I'm the guy who collects beryllium and slices gas cylinders open. Call me a bloody foolish idiot if you like, but I'm not your mom.
All I mean is that melting metals is hard work. It's too hard to be wasting time getting it wrong. Learn something before you light up, then maybe you'll get to the useful aspects of it rather quicker.
-- Die Gotterspammerung - Junkmail of the Gods
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Alpinekid wrote:

Paint??? Arrrrrgh!!! Stand upwind, burning paint is Toxic.
Charly
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Alpinekid wrote:

Could it be something else? Maybe, but not likely. Making a gas bbq housing out of magnesium would be dangerous and expensive, not something that the Corporate structure would see as a good marketing concept.
Is it too oxidized to recover? Is it still in one piece, or has it turned into a pile of gray flakes?
Do you get the metal back? No. Combustion fire usually isn't hot enough to break the chemical bond, that's why you use a LOT of electric current to get the aluminum out of the bauxite. It takes about ten times the energy to smelt as to remelt, thus the big recycling effort. Just what were you planning on using to melt your scrap? I suggest gas. Normally aspirated propane is plenty of heat for aluminum. A Caution here... liquid metal is damn dangerous to handle. One splash in the wrong place can maim you for life. Before you do anything, plan the path that your hot metal is going to pass through and leave yourself an escape route. Cramped working conditions lead to Bad Accidents, give yourself room to move.
Charly
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Thanks for the reply.
Charly the Bastard wrote: e

I havent got that far yet. I'm studing the various site that show homemade furnaces and burners.
Right now I'm in the big city but I'm building a house on 40 ac. Lots of scrap aluminum here and lots of space there:-)
I'm sort of communting, at least I was until my job ended here so now all I'm planning on doing is building, until the money runs out:-(

I dont really plan to melt until I'm settled in my new place. Lots of room there. Its in a volcanic area north of Flagstaff. Lots of safe places to set stuff down. Volcanic cinder and a very fine silty clay. I wonder if its useful for the clay in a homemade refractory.
Al
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People! This is not a foundry NG! Sorry , but there is precious little talk about iron at this NG as it is. Who cares about sloshing hot liquids around a shop anyway?
Glen G
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