Sciencemadness Discussion Board

Aluminum powder synthesis

Cappy - 2-4-2003 at 17:12

There was enough interest in this that I thought I'd put it here. (for convenience, I am not showing aqueous compounds as ions):

2Al (s foil) + 3H2SO4 (aq) --> Al2(SO4)3 (aq) + 3H2 (g)

Al2(SO4)3 (aq) + 3Mg (s) --> 3MgSO4 (aq)+ 2Al (s powder)

You say the following reaction will occur:

Al (s powder) + H2O (l) --> Al(OH)3 (s)

If I added excess Mg, the following would occur:

Mg (s) + Al(OH)3 (s) --> Mg(OH)2 (s) + Al (s powder)

I have enough Mg to pull this off, but I'm not sure non aqueous reactants will undergo single replacement easily.

Is there a possiblity that Al(OH)3 would never form in the first place if enough Mg(OH)2 formed first and used up all of the water?



[Edited on 4/3/2003 by Cappy]

BASF - 3-4-2003 at 05:42

I don´t think aqueous media is the way to go because the finely dispersed aluminum could not be prevented from reacting with the water to form aluminum oxides.

What about making the oxalate, then heating to the decomposition temp. in inert gas?
Eventually you get pyrophoric aluminum...

HLR

rikkitikkitavi - 3-4-2003 at 08:30

you can never make pure Al from an Al-compound that contains oxygen by just heating it without a stronger reductant that than Al...

/rickard

BASF - 3-4-2003 at 09:37

Yeah, you may be right.....it was just thinking out of the stomage....i had the methods involving Fe- and Pb-oxalates for pyrophoric iron and lead in mind, but forgot considering they are more or less heavy metals.....:(

BASF - 3-4-2003 at 09:58

This thread is discussing all about making aluminum powder, especially atomized aluminum.
It seems that pyrophoric, atomized aluminum powder or weapons-grade aluminum is fairly hard to do.
Maybe there is a chance to make flake aluminum, which is also very reactive....

http://yarchive.net/explosives/aluminum_powder.html

Organikum - 7-4-2003 at 23:31

good link BASF!

cost me a few hours I would have had to spend with urgent work.

:(:(:(
;);););););)
ORG :D

Al powder

Theoretic - 24-6-2003 at 07:42

If you need Al powder for thermite mixtures or burning, you could just file it from a Coke can (and use a sieve to separate the finer component if you want to, since Al powder made with that method comes in all sizes. Grainy powder would do for thermite mixtures).

vulture - 24-6-2003 at 08:01

That's going to take ALOT of time.
Electric grinding isn't an option because you would have lots of dust floating around while getting a red hot coke can due to friction.

Not my idea of being safe...

DDTea - 24-6-2003 at 08:17

If you want to have Aluminum powder by means of a single-replacement reaction, why not have the byproduct be solube in water, thus facilitating the extraction of the Aluminum? Unfortunately, I can't think of any ion that would make this possible :(.

vulture - 24-6-2003 at 08:56

2AlCl3 + 3Mg ----> 3MgCl2 + 2Al?

However, this can not be done in water, as the AlCl3 would hydrolize. Hmm, pure liquid (it's a liquid at room temp IIRC) AlCl3 and simply adding Mg? MgCl2 solidifies and shifts the equilibrium to the right?

I can't say why, but my intuition says this wont work...:(

madscientist - 24-6-2003 at 09:43

I think AlCl<sub>3</sub> melts just below 200C. :)

Replacement reactions will typically yield metal crystals that are far larger than the particles found in a powder.

Iv4 - 26-6-2003 at 02:58

IMHO the best way of making fine AL powder is taking some foil and adding liquid nitrogen(or something to that extent)and using a mortat and pestle on it.Though that's probably not very convenient(though a cryo cooler could be made from the materials in extremely condducitve thread and that might be able to pull it).

I've heard of water and foil in blenders.Suposedly the water in it keeps the heat acceptable.Paranoid as it may seem I'm worried it might liberate hydrogen and oxygen.

Twed The Terrible - 1-7-2003 at 11:01

Go get some metallic paint. The sort that dries with the shiny metal in it, like that on some cars. Guess what the shiny metal is....Al! Wehey!

Now, add a generous amount of solvent (I use acetone) to the paint to thin it down to a watery thickness. Filter the mixture to remove the Al particles. Wash them, dry them, and do what you want with them. Simple.

[Edited on 1-7-2003 by Twed The Terrible]

blip - 2-7-2003 at 14:09

I read a great article on making magnallium powder where you alloy aluminum and magesium in a 1:1 ratio. It's brittle even at room temperature, so you can just use a hammer to break it up.

GZAust - 11-7-2003 at 06:45

Where are you thinking of getting the 3 mol of Mg? Sharpeners?

50 or so grams of Al isnt a lot for two steps and all that Mg, but I'm all for the chemically atomised product! very cool


Doesnt most foil have a chrome coating on one side? In aus they do.

Iv4 have you tried lateral thinking puzzles? - You'd be great at them :)

I wonder if CO2 would do it? But I don't know how to freeze CO2, placing the compressed gas in the freezer? :D

Organikum - 12-7-2003 at 14:49

How to freeze CO2

open the valve

:D

Marvin - 13-7-2003 at 04:06

Under optimum conditions making solid CO2 by expanding from a room temp cylinder wastes about 75% of the CO2. Putting the cyclinder in the freezer would probably help a bit but buying dry ice directly from icecream sellers is probably the way to go here.

I'm unsure if it would be cold enough to make the aluminium brittle, but it shouldnt be used anyway. CO2 is not inert to aluminium powder and a mix of aluminium dust and CO2 gas is flammable/explosion hazard.

Ballmilling paint grade aluminium or aluminium foil is supposed to work quite well at room temp dispite mallability. Inert gas of some sort would be a must there I think, and the result could be pyrophoric. Not tried this yet, the paint grade Al Ive been able to buy here is rather course.

Mongo Blongo - 13-7-2003 at 04:54

You can buy Al powder from Fibreglass suppliers. Does anyone know how fine /mesh the powder is? (I have yet to get some)
You can also get Brass,Bronze,Copper and Nickel powders.

Organikum - 13-7-2003 at 09:18

Marvin: Yes it´s a waste but dryice isn´t easily available where I live but CO2 bottles are and they are asscheap here. Get a bottle with two adaptors where one is for taking out liquid CO2. Filling the liquid CO2 in a thermoinsulated bucket makes it freeze instantly by the cooling invovlved in the expansion and phasechange on the surface and the special properties of CO2 which goes from solid to gaseous state directly. The liquid state in the bottle resembles a kind of denaturated solid phase. The losses are not so big this way.

Very important and right on the point is that CO2 cannot be regarded as inert gas for chemistry. Argon is most favorable (pure no welding mixture) and nitrogen as cheaper substitute in most cases sufficices.

Mongo Blongo, might you hint me to the fibreglasssupplier carrying the metal-dust. Mine doesn´t. :(

Mongo Blongo - 14-7-2003 at 06:05

Cheak your email. ;)

AngelEyes - 14-7-2003 at 06:58

I have tried the fibreglass (cold-casting) metal powder additive. It's definitely Al, but it seems very difficult to get it to any usable state. Rinsing with acetone seemed to do nothing - in it's present state it can be ground up with NaNO3 and it still won't ignite. You'll get the occasional spark coming off it...but that's all. No good for flash.
I have heard it said that you can put in the oven for a few hours at 200 Celsius (or thereabouts) to remove the coating on the Al, but I have not tried this. Anyone confirm if it works or not? Anyone confirm if there even is a coating, and it's not just mixed with an inert 'filler' to pad it out?

If you're looking for this stuff just do a search for fibreglass, resin, metal powder and the metal of your choice - you can get copper, bronze, brass, aluminium etc. No Mg though :-(

I have a few pots of various metal powders but no way to turn it into a really useful product.

Another weird idea...

BASF - 29-7-2003 at 02:32

Melt aluminum with an inorganic salt(or a combination of different ones) having the same specific density and melting point.
The hope is this would then mix thoroughly and the inorganic salts could then lateron be washed out by means of a suitable organic solvent.
(It is understood that the number of inorganic salts soluble in organic solvents is quite small.)

I know this would afford a LOT of experimenting and recherche, but who knows...

vulture - 29-7-2003 at 03:10

I have heard it said that you can put in the oven for a few hours at 200 Celsius

Even if it did work in removing the coating, you'll be reinforcing the oxide layer on the particles. You'll be left with 80% Al and 20% Al2O3 layer on the outside which makes the particles very unreactive.

Any means to remove the oxide layer attack the aluminium as well.

Aluminium powder grades

chemoleo - 16-10-2003 at 12:05

although it's slightly off topic, does anyone have information on the different grades of Al powder?
For instance, there are the 'mesh' grades, which come in 200, 400, 600 etc. What does this stand for? 200 micrometer particles?
Also, then there are varietes like dark German Al powder (dendritic?) , or American etc - what are those? Especially the dendritic version, sounds to me like some nano-crystallised form - how the hell is that made??


PS I am sure a number of people have been wondering the same... so hail to my bravery for askign this... or flaming me for asking something as seemingly trivial? ;)

[Edited on 16-10-2003 by chemoleo]

blip - 16-10-2003 at 15:14

This is the closest thing I could find, I think this page was mentioned here: http://www.fisher.co.uk/techzone/tables/chemicals1.htm#Sieve...

I've gotten into the habit of collecting useful links and saving them into text files for future reference, sometimes it really helps.

Wolfram - 17-10-2003 at 16:23

Would you please stop call powdering metal for "synthesis". Synthesis suggest at least that you make something more complicated from less complicated, the compunds you use should be organic.

Preventing aluminum oxide

tom haggen - 29-11-2003 at 16:10

i'm somewhat new to the chemistry field but i have been studying metal for 3 years now, i have been expirementing with aluminum powder as a fuel because that seems to be the most widely used fuel in flash powder and its easier to work with than magnesium. anyway, I went to the camping store and bought one of those fire starter strips that came with a strip of magnesium glued to a bar of cast type aluminum. i filed this stuff down and the grade was very fine. however i flashed up somewhat. so i mixed this with an oxidizer and when i burn't it i kept leaving chunks of unburnt oxidizer. then i read a synthesis about using a binder like water or something,and mixing your composition wet is this what i need to do to get better results. and if i do need to use a binder will water create aluminum oxide in my compostion.

P.S. i filed down some 6061 common aluminum and this stuff didn't burn for crap. leading me to believe that you need a special series of aluminum to create the pyrophoric aluminum powder.

-Tom

Hermes_Trismegistus - 30-11-2003 at 00:34

GUYS

pretty much all aluminum you are going to get is going to be an alloy!!!

pop cans and aluminum foils are NOT pure ALuminum How did you think that pop cans are so strong or that aluminum foil has a shiny side anyway????



if you do find some aluminum (smelting with flux is cheap and easy)just look at my BALL MILL post in apparatus

it will (slowly) give you all the aluminum you need

however you can't really use aluminum alloys because they are specifically formulated to avoid stress fracturing which is what allows the powdering of fairly pure aluminum in a ball mill

also aluminum oxide powders much more easily in a ball mill that Al metal, since it forms the oxide almost instantly on contact with air (and thats what you get when you buy al powder) (for the most part)..........

[Edited on 30-11-2003 by Hermes_Trismegistus]

unionised - 30-11-2003 at 04:09

If the aluminium powder was mainly oxide;
1 It wouldn't work and
2 It wouldn't look like aluminium.
Of course, it will have the annoying oxide layer, but that is thin, even the layer on anodised Al is only about 10 or 20 microns.
Wolfram,
What's wrong with inorganic synthesis?

[Edited on 30-11-2003 by unionised]

Aluminum powder

MadHatter - 1-8-2004 at 13:40

Ball milling is the easy part. The mill is doing the work for you.
The problem is filtering to the desired mesh. An old shirt or tightly
woven fabric should do the trick. If the powder is dusty through
the filter, it's fine enough for making a good flash.

BromicAcid - 1-8-2004 at 19:22

Ran across an interesting article on nickel powder production. Although not economical it called for making a sodium dispersion in mineral oil and heating it to 200C with constant stirring then adding NiCl2 (anhydrous of course) with constant stirring. Pyrophoric nickel powder is the result after adding alcohol to decompose remaining sodium and filtering.

So possibly anhydrous aluminum chloride could be reacted with dispersed sodium but maybe something stronger like potassium would be needed to produce your aluminum powder. Again, not practical but interesting.

(Yes, I could do the thermodynamic calcultions like I'm wanting to but it's getting too late, maybe I'll edit this tomorrow.)

Edit: Even though it's late I compared the delta H of the two reactions, the one for nickel chloride reacting with sodium releases 517 kJ and the theoretical one with aluminum chloride releases 592 kJ therefore the reaction is comparatively exothermic.

[Edited on 8/2/2004 by BromicAcid]

Theoretic - 20-10-2004 at 04:46

Sodium will reduce AlCl3 just fine, anyway your calculations show it.
I read somewhere in this forum that at a high temperature, Al is brittle. Maybe it could be ground down into a powder with a mortar and pestle, under a blanket of N2 gas to prevent oxidation (some AlN will form, but much less aluminium will be wasted and the powder will be more reactive that with an oxide layer. The mortar would be heated with a flame (if one uses electric heating then an added bonus is that H2 can be used for shielding the metal, no stuff will form on the surface), you have to admit that (ceramic) mortars make damn good crucibles.

vulture - 20-10-2004 at 05:35

Nuclear fusion is pretty damn exothermic. Does it therefore happen spontaneously? No.

You need to calculate the gibbs energy to be sure.

Organikum - 20-10-2004 at 06:53

Actually the literature states that Al reduces NaCl to the metal. It is mentioned IIRC in the sodium article in the SCM library whic was provided by Bromic_Acid.

I am a fish - 20-10-2004 at 07:17

Quote:
Originally posted by vulture
Nuclear fusion is pretty damn exothermic. Does it therefore happen spontaneously? No.

You need to calculate the gibbs energy to be sure.


Gibb's Energy does decrease in nuclear fusion (at least in the reactions proposed for energy production). It doesn't happen spontaneously for kinetic, not thermodynamic reasons. Energy is released by the nuclei attracting each other, due to the strong nuclear force. However, this has an extremely short range, and so energy must first be expended in overcoming the mutual electrostatic repulsion of the nuclei.

neutrino - 20-10-2004 at 19:07

Gibbs free energy doesn't tell you whether a reaction will occur in a reasonable amount of time. Some things that should be spontaneous at room temp have to be heated considerably to work at a noticeable rate.

Now, a thought on cleaning the oxide layer off: adding concentrated nitric acid. The following two reactions (or something close to them) should occur:

Al<sub>2</sub>O<sub>3</sub> + 6HNO<sub>3</sub> -> Al(NO<sub>3</sub>;)<sub>3</sub> + 3H<sub>2</sub>O

2Al + 6HNO<sub>3</sub> -> Al<sub>2</sub>O<sub>3</sub> + 3H<sub>2</sub>O + 3NO<sub>2</sub> + 3NO

There should be en equilibrium between how fast the oxide layer is taken off and how fast a new one if made. This final thickness might be very thin or very thick. Does anyone have any experience with this?

Blackout - 3-12-2004 at 18:52

you could put Al foil in a blender with NaCl until you have a powder.
you could have a more finnest powder by oxidize the Al powder you've made before and grind it in a coffee-grinder to get a finnest powder an the heat it (with a gaz burner; blue flame) with charcoal powder and bubbuled the CO2 in water. Decant the C, you will get a very fine Al powder.

Blackout - 3-12-2004 at 18:56

oh, you can stop to heat when no more CO2 is given off.

BromicAcid - 3-12-2004 at 19:10

I wasn't really saying that the delta H was justification. Just that they were comparatively exothermic and therefore could probably be carried out in the same medium, there was the chance that the reduction of aluminum chloride with sodium may have been considerably more exothermic and affected the solvent adversely. However they release about the same amount of energy.

I knew the reaction itself, that between sodium and aluminum chloride would work because that is the way that aluminum was originally 'mass' produced. Quite expensive that way but workable. That is until the invention of the Hall process displaced it.

Of course I fogot to take melting/subliming points of AlCl3 into play.

[Edited on 12/4/2004 by BromicAcid]

Marvin - 4-12-2004 at 08:13

Blackout,

You cannot reduce alumina with carbon.

kclo4 - 29-12-2004 at 21:50

is there was a way to get Al powder from Al2S3

evilgecko - 2-1-2005 at 20:50

I by some aluminium window frames and then attack them with my angle grinder with a very large disc on it. A cardoard box is put around the vice so it catches most of the particles. Then I ball mill them with iron rods for a day.

nodrog19 - 9-6-2008 at 20:13

mesh size is hole/sq in (6.55 sq cm)
its crimminaly american.
try shredded foil in coffee grinder.

Tinton - 9-6-2008 at 21:20

If you are going to obtain particles as small as you're theorizing, you might need an alternative to filtering. Many filters available to the home chemist quite frankly, suck.
I haven't seen any filters that can separate good mesh metal powders efficiently on any of the supplier's websites.
Correct me if I'm wrong, I haven't been equipment-searching in a while.

evil_lurker - 9-6-2008 at 22:03

Easiest way I have found to do it is to use what is known as a "step bit" in a drill press on sheet metal, followed by grinding the turnings in a coffee grinder, and then ball milling to size.

PITA, yes, but it works.

Luckily I have access to 1100 series aluminum, which cuts very easily. The coffee grinder is where most of the work gets done very quickly, and the milling can take several days for "black" or "dark" aluminum.

I have found that a standard Harbor Freight single barrel rock tumbler is most acceptable for powdering. Harbor freight also sells a dual barrel model, but they just don't seem capable of handling two fully loaded drums worth a crap. Under such conditions the motors produce a lot of heat and the cheap drive belts break quite easily... in my experience one can expect to break a belt every 1-3 days, sometimes they go in only a few hours.

It also helps to increase the gear ratio slightly. The easiest way to do it is to first is to slice a section of correct sized ID PVC tubing down one side and then affix it around the main drive shaft. This causes the shaft to get bigger and as such the drums turn faster giving more of a pounding action.

The best media IMO would be chrome steel bearings, and if they are too expensive for one's taste case hardened steel bearings second. All bearings can be purchased from the Ebay seller "toolsupply" pretty cheap IIRC. Alumina is just too light (bout half the weight of steel) to give a decent grind and of course lead is just too soft.

Sizing is somewhat up in the air, but my first choice for a harbor freight mill would probably be 9/16" first, 1/2" second, and 5/8" third. I'm guessing that one cup in volume would equal in the neighborhood of 120 1/2" ball bearings.

Appropriate charge I'm guessing is somewhere a little over a cup, and around 125g of aluminum. Again its just a guess. I'm sure some pyro expert would be much more knowlegable of proper ball mill loading than me.

[Edited on 10-6-2008 by evil_lurker]

nodrog19 - 11-6-2008 at 15:54

add some rock salt to the mix.
if i can get a blender, i might start selling
it. reynolds alum foil is 97% Al, 1%Fe, 2% Sn
w/ a polymer coating. if you want to get really pure,
wash w/ a solvent and the digest in HNO3

not_important - 11-6-2008 at 17:18

Use cheaper generic foil and avoid the polymer, or just do not use the Reynolds "non-stick" varieties .

Cooking foil is usually a 1xxx alloy, 99+ percent Al with fractions of a percent of iron and silicon unintentionally picked up in production of the metal. I'd like to see a reference for that alloy you gave, especially as tin is not a common alloy additive for Al.

Diablo735 - 16-6-2008 at 19:06

Referring to the blender idea of making Aluminum powder: I have read in other threads here and on other websites that one can use other materials to keep the Aluminum on the bottom near the blades. One of the most interesting ideas I found was using water... but my friend brought up a good point that wouldn't that cause oxidation to the "powdering" Aluminum? (significant enough that the result will be more oxidized than not...)
(Sorry if that is an elementary question.... I am about start Gr 12. :D)

bigbigbeaker - 16-6-2008 at 20:15

Many decades ago, when I got the "After Dinner Science" book for my birthday, the first experiment I tried was mixing iodine crystals and powdered aluminum with a drop of water. The druggist who sold me the iodine sent me to the art store to buy a one ounce bottle of aluminum dust pigment. It's so fine it seems to float. If you just need a very fine, highly reactive aluminum, then take shredded Al foil, a bunch of 50 caliber lead balls and ball mill it for 3 days. If you want to try the paint route go to Richard Nakka's rocketry website. There's is alot of good rocketry info there and he gives detailed instructions for harvesting Al from paint. Here's the link - www.nakka-rocketry.net/igniter.html#Aluminum. If you are planning to make flash powder, learn what you're doing first. An unenclosed 30 gram pile of it "detonates" with amazing force. Make sure the humidity is 40% or higher and ground yourself with a wrist strap. Better safe than sorry. An accident with an energetic can be life changing or ending.

LSD25 - 16-6-2008 at 22:27

2 seconds on google found this

http://www.pyrobin.com/files/manufacturing%20of%20flake%20al...

They utilise scrap Al foil to prepare fine Al Flake/Powder using a ball mill and inert atmosphere.

Next, design ideas - any thoughts?

nodrog19 - 17-6-2008 at 20:53

oops, it was silicon.
"Reynolds Wrap® Aluminum Foil is 98.5% aluminum. The balance is primarily iron and silicon. These are added to give the strength and puncture resistance obtained only in the alloy used in Reynolds household foil."

497 - 10-9-2008 at 01:57

Have a look at this! Production of Al powder down to less than 100 nanometers, the best a mill could do is maybe 5000 nanometers! And the best part is it is all done in an OTC liquid phase solvent (toluene).

http://www.google.com/patents?id=koIYAAAAEBAJ&printsec=a...

And here's a patent on preparation of the required aluminum hydride:

http://www.google.com/patents?id=Pf0FAAAAEBAJ&printsec=a...

The problem is getting the alkali/alkaline hydride... I think most everything else involved is not too hard to find or synth. Maybe buy sodium (>$50/mol) and react w/ hydrogen? Ugh that sounds like a pain in the ass, there must be an easier way?

Hmm now I can't stop thinking about all the things I would love to try with that super fine Al :P

Picric-A - 10-9-2008 at 11:51

If you are looking for mesh filters:
www.inoxia.co.uk sells em quite cheap (in UK)
cant you just put Al foil in a blender then ballmill for 3-4 days then filter it to seperate it?

panziandi - 10-9-2008 at 12:00

I remember reading once on the side of a kitchen foil box that it listed ingredients and among them were manganese, iron, and various others I can not recall. I assumed that these metals in the alloy were what the grey powder was that resulted from dissolving aluminium foil in NaOH... I suppose for pyro these impurities don't matter, but if you are using the aluminium for something more demanding...? I have never been able to find a box with the ingredients listed again (Although I think it may have been Waitrose brand in UK).

Picric-A - 10-9-2008 at 12:20

manganese and iron :O that doesnt sound good :P
i had better stick to a differen source of Al for powder then :P
You can buy it from metal work shops for casting, i may have to look into that option...
then grinding with a metal grinder and channeling the powder into a bow to collect ect...

panziandi - 10-9-2008 at 12:52

Perhaps it would be interesting if somebody with the time and resources could analyse aluminium foil for the % composition of Mg, Mn, Fe, etc and post the details, perhaps comparing to Al of LR grade available cheaply from many lab suppliers (in a powder although not usually the extremely fine dark grades)

ScienceSquirrel - 10-9-2008 at 17:32

I have made common alum ( potassium aluminium sulphate dodecahydrate ) from a variety of aluminium sources.
The aluminium is dissolved in excess potassium hydroxide solution, filtered and then neutralised with sulphuric acid.
I have used sheet metal from cans, foil and LR grade aluminium powder and I have always had a fine black precipitate left in the alkaline solution.
As a guesstimate I would say that it is a few percent on average, some of it is magnetic while other particles are not.

Very pure aluminum metal is not cheap!

Panache - 10-9-2008 at 18:06

there are some 22,000 known Al alloys/compositions/treatments and counting, something made of aluminum is rarely 100% aluminum. Foil esp. so, generally containing the above mentioned stuff. Luckily here in Australia the land of the free and rational it is illegal to sell Al powder but everyone seems to sell it! Liquid N2 is cheap ($59.00 for 1-60L, price same regardless of how much lol, my dewar is only 15L but i'm always tempted to order 60L and make a huge batch o super-fino ice-cream) Can you pulverize al to powder after cooling it?

Actually maybe there are 22,000 types of thread profiles, and 2200 known al alloys, i always mix those two up. The alloys one is from a Mat Scientist speciailising in Al and Mg alloys, he's been researching al alloys for 40 years so i'd believe that one, the thread number is from my father, and it made up part of his rant as to why the British are stupid, he would quote the number of thread the british had developed, so that maybe wrong, he's german and prone to exaggerate.

Overall this post provided very little real help or information, apologies for that!!

497 - 10-9-2008 at 18:39

Quote:

cant you just put Al foil in a blender then ballmill for 3-4 days then filter it to seperate it?


Sure you can... this has been discussed time and time again. No one will ever get aluminum powder out of a mill that is anywhere near the reactivity and power of precipitated 100 nanometer Al (not to mention an amateur mill!). That is why I think it would be better to work on finding a way to semi economically produce a precipitated Al powder rather than trying to adapt/improve a process that has already been optimized to its full potential (milling). Just my opinion.

What are you worried about a % or two of iron? You realize there would probably be at least that much added by milling in with steel media? And BTW there is no need to pregrind the foil prior to ball milling, just tear it in strips. Let the mill do the work..

Also, unless you use a very low ratio of Al:steel media (eg <1:20) you will probably get a pretty low quality product. The problem with this is that it required a very large mill to produce much Al powder at once. For example a 5 gallon mill filled with 100 pounds of 5/8" steel media might give you at most 5 pounds of 50-200 mesh powder after a few days of milling. Then you have to separate that 100 pounds of steel out...

[Edited on 10-9-2008 by 497]

grndpndr - 13-9-2008 at 23:05

I have perhaps 30lbs of railroad themite welding material its utilized by RR track crews using forms to weld the ends of the ribbon type rails, filling with the thermite comp and igniting the thermite, forms apparently helping contain the heat. The welding thermite appears to consist of black Iron oxides small lumps of some type of nonmagnetic alloy/flux? material and of course a large % of coarse AL.Seperating the AL/Iron is relativelty straigtforward w/magnets but time consuming as it requires several passes with magnet to ensure Iron partcles arent included in the AL powder, the larger(nonmagnetc) golden hue globles of very hard flux/steel alloy ?material are removed by hand so even at that point of seperation its a time consuming process.For what I woud put at 100-150 mesh sperical being my guess usng a low powered magnifyng glass and 'feel'.
Cetainly not a pyro grade as it is but what other possibilitys could one see for this material? i hate to simply trash this much
thermite based welding material given the flaked black Iron oxide/AL content material that cost $0.Rather than a ball mill has anyone tried a vibratory relading case cleaner with steel shot/etc as the AL reducing agent? The vibratory reloading case prep machines are intended to operate for extended periods if needed .
Assuming this material turns out to be 100-150mesh sperical AL as is would it be suitable as is fuel for small charges (4-5 kilos) Binarys etc 25/75- AL powder as fuel/ appropriate oxidizer and substantial booster
w/o further reducing w/ball mill or eqiuvalent?The Reducing experient wouldnt cost much as the vibratory case cleaner is on hand as is the partialy reduced AL powder.Ball Bearings of a suitable size could also quite likely be scrounged but for curiosity sake if anyone thinks this is viable what size steel bearings would you use?Bearings are all that are required
to answer the question unless someone has tried it before and can either confirm success or save me some time not proceeding,though a couple doubts would'nt dissuade.:) Any thoughts -suggestions as to reducing AL other possibilitys for material much appreciated However.

[Edited on 14-9-2008 by grndpndr]

[Edited on 14-9-2008 by grndpndr]

[Edited on 14-9-2008 by grndpndr]