making magnalium

[WSM]

This is an interesting paper on lower temp Magnesium chip recycling: https://www.researchgate.net/publication/269407851_Re-Melting_of_Magnesium_Chips

I wonder if the aluminum could be added to the Mg after melting rather than the usual reverse process?

 

This article looks like it'll answer the question. With the proper setup, those who have a stock of magnesium turnings could convert it to a more useable form. Thank you for this information. Muchas gracias, Amigo.

 

WSM

[WSM]

patrick if you run into a book melting magnesium chips for dummies let me know.......

 

Too many liabilities, maybe? Really, dummies shouldn't be doing that (too risky!).

 

WSM

[WSM]

This is an interesting paper on lower temp Magnesium chip recycling: https://www.researchgate.net/publication/269407851_Re-Melting_of_Magnesium_Chips

I wonder if the aluminum could be added to the Mg after melting rather than the usual reverse process?

 

That's a good question.

 

If you had two melting pots and poured melted aluminum into the magnesium melt (without splashing), then stirred it; I don't see why it wouldn't work. Is there a great difference between the melting point of aluminum and magnesium?

 

WSM

[OldMarine]

Al melts at 1220°F and Mg at 1200°F. I think that's a negligible difference and below the ignition point of the Mg.

[pyrojig]

Sadly I have attempted a couple ways to reduce mag chips in a melt, but with no luck. The melting point is close to the ignition point . A gas blanket wold be incall for to keep the mag from going off. As for meting the mag 1st it is a PITA and almost always goes off in ignition . The Al melt helps suppress/ suffocate the mag .

[OldMarine]

A simple carbon dioxide blanket should stop ignition I would think and would allow the Mg to be raised the few more degrees needed to melt the Al. I'll have to buy another crucible before I try it but have CO2 that I use for beer for the attempt..

The crucible I have now is iron since I've only played with casting brass but it will form oxides that will react with Mg no matter how well I clean it. A silica or graphite base one may be a better choice.

Edited July 30, 2016 by OldMarine

[mikeee]

Have used stainless steel containers in the past to cook magnalium in with no problems.

[WSM]

A simple carbon dioxide blanket should stop ignition I would think and would allow the Mg to be raised the few more degrees needed to melt the Al. I'll have to buy another crucible before I try it but have CO2 that I use for beer for the attempt..

The crucible I have now is iron since I've only played with casting brass but it will form oxides that will react with Mg no matter how well I clean it. A silica or graphite base one may be a better choice.

 

I'd avoid any oxide, even CO₂.

 

Magnesium is such a potent "getter", it'll strip oxygen from almost everything. If I'm correct, CO₂ on a magnesium fire would explode.

 

WSM

[memo]

I think dagabu tried putting a pressed puck of turnings into molten al. he said that you should wear full leather because it would blow out of the crucible. with out having the right equipment to melt the turnings I think your screwed. I will be checking the scrape people for the mag or try and buy it if available.

 

memo

[OldMarine]

 

I'd avoid any oxide, even CO₂.

 

Magnesium is such a potent "getter", it'll strip oxygen from almost everything. If I'm correct, CO₂ on a magnesium fire would explode.

 

WSM

I have argon, which I haven't read up on and nitrogen, which is a no-no because it reacts badly with the Mg from what I've read. I found several articles listing solid fluxes that are pretty common and I'll read up a bit more on those before thinking of trying them. Sodium fluorosilicate is mentioned and I have access to it.

[Mumbles]

Mg and CO2 does in fact burn. It's a semi-common lab demo actually. You put a lit magnesium ribbon into a cavity inside or between blocks of dry ice. It glows very brightly as it burns, and leaves a layer of carbon all over the cavity in the dry ice. Pretty neat if you ever get a chance to see it.

 

I wonder if using an inert gas (preferably argon) inside of a sealed crucible would work. Something like a stainless drink shaker was popular for a while. I suspect it's possible someway to remelt Mg turnings into ingots. When I was glancing through the pdf that was posted earlier, it sort of seemed like they add Mg chips to molten Mg or mix together ingots and chips/turnings. I didn't get a chance to read all that closely, so I might have missed something.

 

My other thought was to use a protective flux layer over the aluminum. It's not perfect, but something like potassium chloride might work. It does melt about 100 degrees C higher than Al or Mg, but in the molten state both metals are less dense than KCl. Lithium chloride is the ideal candidate. It melts about 50 degrees C lower than either Mg or Al, and is less dense so it should float to the top. It's not as OTC as potassium chloride though.

 

http://moltensalt.org/references/static/downloads/pdf/element-salt-densities.pdf

[OldMarine]

Strange there's so little info on the web. I would think it would be as common as aluminum smelting/casting in the hobby world.

[MrB]

 

 

WSM that is what i have read also. what I don't know about is ball milling the magnalium. will lead balls in a rebel mill jar work, being rubber lined soften the impact to much ?

 

No idea on the liner, and it's effect, but lead for milling magnalium is a no go. It just eats up the lead.

 

 

More germane to the subject, has anyone figured out an effective method of converting (smelting) magnesium turnings into a solid mass that can be used to make magnalium from?

 

Many of us have or have access to magnesium turnings, with no effective practical way to use them. Some have suggested milling them to powder, but that seems too dangerous without an expensive setup to do it safely.

 

I'm open to discussion on the matter...

 

Purely speculation, but compressing the shit out of it? Sure, milling it to a powder first could improve the quality of the compressed "pill" but i doubt it's necessary.

Anyone looking at making magnalium probably has a press anyway, so compacting it shouldn't be impossible?

 

Al melts at 1220°F and Mg at 1200°F. I think that's a negligible difference and below the ignition point of the Mg.

 

Isn't part of the problem that magnesium has a lower ignition temperature, then it's melting point? It's in the region of 470c for it to burn, and 650c to melt.

 

A simple carbon dioxide blanket should stop ignition I would think and would allow the Mg to be raised the few more degrees needed to melt the Al. .

 

Not sure. The smallest amount of oxygen will trigger a chain reaction where the Mg starts stripping oxygen from the CO2. If that can be prevented, then perhaps.

 

 

Magnesium is such a potent "getter", it'll strip oxygen from almost everything. If I'm correct, CO₂ on a magnesium fire would explode.

 

 

On a fire, yes it would. But if it can prevent ignition? It's the high temperature that decomposes CO2, to strip the O and make it available. Would it still ignite with only CO2 in the surrounding?

 

 

My other thought was to use a protective flux layer over the aluminum.

 

 

Sulfur?

B!

 

Edit

Ok, so quotes got screwed up. I'll try and fix it later. I'm sort of in a hurry, i'll be back, sorry.

 

The preview says i got it... Lets try it out.

/Edit

Edited July 30, 2016 by MrB

[WSM]

Al melts at 1220°F and Mg at 1200°F. I think that's a negligible difference and below the ignition point of the Mg.

 

It helps explain why melting the aluminum first helps, plus the vastly more active magnesium is less prone to burn if it's surrounded by molten aluminum instead of melting in the atmosphere. Molten magnesium and aluminum can react with the atmosphere (oxygen AND nitrogen) to form oxides and nitrides (and possibly a host of combination products).

 

Aluminum usually gets a protective layer of aluminum oxide which protects the metal under the surface, but magnesium doesn't do that, but it rapidly combines (with oxygen or whatever) till the reaction is self-sustaining and can become a runaway reaction very quickly.

 

WSM

Edited July 31, 2016 by WSM

[WSM]

Mg and CO2 does in fact burn. It's a semi-common lab demo actually. You put a lit magnesium ribbon into a cavity inside or between blocks of dry ice. It glows very brightly as it burns, and leaves a layer of carbon all over the cavity in the dry ice. Pretty neat if you ever get a chance to see it.

I wonder if using an inert gas (preferably argon) inside of a sealed crucible would work. Something like a stainless drink shaker was popular for a while. I suspect it's possible someway to remelt Mg turnings into ingots. When I was glancing through the pdf that was posted earlier, it sort of seemed like they add Mg chips to molten Mg or mix together ingots and chips/turnings. I didn't get a chance to read all that closely, so I might have missed something.

My other thought was to use a protective flux layer over the aluminum. It's not perfect, but something like potassium chloride might work. It does melt about 100 degrees C higher than Al or Mg, but in the molten state both metals are less dense than KCl. Lithium chloride is the ideal candidate. It melts about 50 degrees C lower than either Mg or Al, and is less dense so it should float to the top. It's not as OTC as potassium chloride though.

http://moltensalt.org/references/static/downloads/pdf/element-salt-densities.pdf

 

I believe a slow argon feed would work beautifully. It only needs to be slightly positive pressure to keep atmospheric gasses out.

 

I think something as pedestrian as a cast iron dutch oven would make a great crucible.

 

WSM

[WSM]

I have argon, which I haven't read up on and nitrogen, which is a no-no because it reacts badly with the Mg from what I've read. I found several articles listing solid fluxes that are pretty common and I'll read up a bit more on those before thinking of trying them. Sodium fluorosilicate is mentioned and I have access to it.

 

Argon should work great (being an inert gas). I think Mr B suggested sulfur as a flux, and I recall hearing that sulfur thrown on molten Mg prevents it from burning (if I remember this right, or does it smother burning Mg?).

 

Let's get this right before we proceed...

 

WSM

Edited July 31, 2016 by WSM

[OldMarine]

Yup, I'm reading up before jumping in

[MrB]

 

I think Mr B suggested sulfur as a flux, and I recall hearing that sulfur thrown on molten Mg prevents it from burning (if I remember this right, or does it smother burning Mg?).

 

 

 

I did, and it does both. It's a crappy "flux" as it wont return any of the oxides back to it's pure form, and it smells a bit. But it kills any flames, and prevents new fires. I don't understand the chemistry behind it, but i suspect it's again down to the high temperature of magnesium fires, making weird chemical reactions possible. I use sacrificial crucibles, (The Al eats them alive, so to speak) melt Al in them, and drop in the Mg. A lid keeps it from roaring flames everywhere, as well as keeping the charcoal fire from contaminating the melt. Once the Mg is melted a quick stir, and just a touch of sulfur to kill the fires. I've dropped in sulfur earlier and then given it the quick stir after everything melts which seams to keep the fire to a minimum, but i suspect that whatever happens on the surface is then mixed in with the magnalium when giving it the stir, so i prefer this way.

I also saw of the top 10% or so and use it exclusively for chunkier material, where it seams the contaminants, (from the charcoal fire, and the sulfur) and oxides isn't really that much of an issue.

 

I've also never tried casting ingots or anything with this stuff. I suspect it would be a horrific mess, and a lot of fire.

B!

[WSM]

It helps explain why melting the aluminum first helps, plus the vastly more active magnesium is less prone to burn if it's surrounded by molten aluminum instead of melting in the atmosphere. Molten magnesium and aluminum can react with the atmosphere (oxygen AND nitrogen) to form oxides and nitrides (and possibly a host of combination products).

Aluminum usually gets a protective layer of aluminum oxide which protects the metal under the surface, but magnesium doesn't do that, but it rapidly combines (with oxygen or whatever) till the reaction is self-sustaining and can become a runaway reaction very quickly.

WSM

 

My only attempt to make magnalium (years ago) involved a very small (jewelry type) kiln and a homemade crucible made of steel. I filled the crucible with a mix of aluminum and magnesium turnings and fired it up for a while.

 

After I powered the kiln down, I let things cool down to ambient temperature and lifted the lid off the crucible. I was disappointed to see only "oxidized" turnings with little melted metal. I then poured water into the crucible and was greeted with some hissing and a strong ammonia smell (Yuk!). Some research revealed that aluminum and magnesium nitrides form in the presence of atmospheric gasses, at elevated temperatures. Calcined aluminum nitride and water produce ammonia.

 

In retrospect, I realized that some problems with my test were:

1. too much surface area on the metal turnings
2. no stirring of the metals
3. not enough time at elevated temperature or temperature too low to melt the metals?

I'm convinced that a propane powered cylindrical forge (not unlike one used for bronze casting), with top access and possible high temperature plumbing for an optional argon purge, would be a better setup. Who knows, maybe just keeping a container of sulfur handy will be all that's needed (plus VERY effective metal casting PPE's) to keep the magnesium from burning off.

 

I still have a lot of preparation and research to do before I'm ready for a serious attempt (I'm still spending a LOT of time researching, experimenting and writing about electrochemistry). I may do a few, small preparatory metal smelting experiments, though. We'll see...

 

WSM

Edited August 4, 2016 by WSM

[OldMarine]

Most of the articles I've searched out were actually from APC and date back years. None offer a workable solution to melting chips and turnings.

Once my new crucible arrives I plan to make a heavy stainless lid with a tap for some 3/8 SS pipe to feed the argon into the crucible and keep it under positive pressure to stop oxygen intrusion.

 

A question: Would treating the mg with dichromate before melting reduce oxidization or accelerate it?

[WSM]

Most of the articles I've searched out were actually from APC and date back years. None offer a workable solution to melting chips and turnings.

Once my new crucible arrives I plan to make a heavy stainless lid with a tap for some 3/8 SS pipe to feed the argon into the crucible and keep it under positive pressure to stop oxygen intrusion.

A question: Would treating the mg with dichromate before melting reduce oxidization or accelerate it?

 

My thoughts were along the lines of a 1/8" stainless tube connected to a stainless compression fitting threaded into the heavy lid. The amount of Ar gas needed is very little, and only a slight positive pressure is required to keep atmospheric gasses out. In fact, the lid of the crucible doesn't have to be tight, only close fitting. I'm thinking that feeding the argon through an inexpensive (+- $22) welding regulator/flow controller would work fine.

 

I don't know if dichromate treating would help or hinder the process. I know chromium tends to have a catalytic effect, but whether that is needed or wanted, I don't know and can't say.

 

Let us know as this project comes together and how everything works. Thanks.

 

WSM

[OldMarine]

My bucket furnace blasts flame around the crucible so I'm concerned any lighter tubing feeding the argon would quickly oxidize and/or melt. I'll attach my regulator hose to the end of a 3' length of pipe to protect it and leave me a handle to hold the lid on while moving the crucible to pour into the bucket.

It's gonna be interesting if nothing else!

[pyrojig]

Correct me if IM wrong, but I believe that OldGuy was the one using the water quenching method. I think it was him who suggested the use of charcoal as a blanket over the melt when done( i believe to suffocate the melt from getting oxygen in the ingots top portion) . I must say the water quenching process is a tad nerve racking , but effective way to get Magnal to a popcorn thin pieces that reduce with ease v.s. ingot . I did however find that the mag from this process ( smaller material seemed less reactive , maybe lost something in the quenching process) . anyone else have this strange reaction ;? Didnt seem to last as long ( shelf life) when reduced.

[memo]

hope you guys get it figured out i only have 4 or 5 lbs of turnngs. it is not worth the time or money to work on it. i was hopng there would be and easy way to do it. I got the turnings for free a few years ago from skylighter so am out nothing.

 

memo

[OldMarine]

I can get turnings by the bucketful from the bike machine shop here so I'll have plenty to play around with memo. My crucible should be here mid week.