metalresearcher
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Making Al powder yourself ?
I have a box of Al lathings, saved from lathing aluminum.
Is it possible to downgrind it to Al powder by using a coffee grinder for hours ?
Does somebody have experience with it ?
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j_sum1
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I would use a ball mill.
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aga
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People have reported good results with even Al foil and a ball mill, so i guess Ball Mill is the way to go.
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NedsHead
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a ball mill works great for grinding Aluminium swarf down to a powder, the turnings are usually very brittle and break down well in the mill, Cody
even did a video on it https://www.youtube.com/watch?v=8rcrHotYico
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j_sum1
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Further to my comment above.
I bought a food processor to grind up Al foil to make my own powder. It takes a long time. It gets hot. The blade gets blunt and ineffective quite
quickly. The powder is not fine. Well, some of it is but you need a fine sieve and there remains a significant fraction of the material in the 1mm
range even after considerable effort.
I have not built my ball mill yet but I understand that it is the way to go.
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yobbo II
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I belived an alloy of Al and Mg will break down better is it is more brittle.
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Dr.Bob
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Using a fast speed grinder, blender or like items to pulverize Al can ignite the Al dust and make a big fire/mess, based on other postings and rumor
mill. I would stick to a ball mill or other slower, safer methods.
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metalresearcher
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How can I get a ball mill ?
On ebay I found some but costs thousands of dollars, probably for industrial use.
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Dr.Bob
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Many people have bought simple "rock tumblers" and more, built them from scratch, or modified other items into them. You might loo on the enegetics
side of the forum, that is where most people looking for Al dust hang out, you can likely search there and get better answers.
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densest
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Ball mills are discussed in fireworks discussions. Look for a publication by Sponenburg on amateur ball milling. !!!PAY FOR IT!!! THE GUY IS BROKE, NO
MONEY. It covers size, media, rotation rates, times - everything you need to know.
*Safety Warning* - it is possible to make enough powder in a sealed jug such that no oxygen is left in the mill jug. The material inside is hot and
not passivated. It can ignite and burn with a very, very hot flame. A knowledgeable pyrotechnician was very seriously burned by milled Mg. The flame
was hot enough to emit substantial amounts of ultraviolet energy. 
Al is not Mg - it can be just as energetic and the Al + O2 reaction is very, very fast and exothermic.
If you're milling down to under 10 micron powder, let the jug cool and let air in very slowly. Under 1 micron (400 nm?) it's a regulated munition.
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Toady
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Tsath' has a safety question.
He recently obtained some Al powder, although not for pyro purposes.
It is in the form of -3micron dust, really, really fine, feels so fine that a little placed between first and second fingers and rubbed between same,
feels like the finest of fine icing sugar, or perhaps very finely ground flour.
He also has some very fine Mg, forget which, either 300 or 500 mesh (quick Q-how does mesh size measurement correlate with mm or micron size of
individual particles of the bulk substance.
It doesn't ignite. That is, neither the Mg nor the Al autoignite upon contact with air, and whilst no effort has been made to ignite the magnesium
there is of course little doubt that it would do so quite readily indeed. The Al, surprisingly, when a pile (and this, for safety reasons if nothing
else, was a small pile, a little heap on the end of a corroded and blunt, rusty, otherwise useless) scalpel blade was heaped thereupon and held until
glowing red hot in the hottest part of the gas flame of the household cooker, when bored, sleepless and with little to do but stare at the clock and
chainsmoke rollups .
Surprisingly it did not ignite. Although when used in a thermite reaction it did indeed ignite and burnt in far from a slowish, steady manner, forget
the mesh size of the Fe2O3, it is simply labelled 'red iron oxide' upon its tin and was purchased long, long before the aluminium or Mg made its way
here. Years, probably. The thermite rxn, using an equimolar proportion of Al to Fe2O3 (with respects to the oxygen content of the oxide) and with a
thin layer of the powdered magnesium atop it to make sure it reached sufficient temperature to ignite...ignite it did, and with a rapid
!!WHUMPFF!! , blazing to a glaring, glowing white hot slag, with chunks in it
that seemed to be perhaps sintered metallic Al in a semimolten, easily fractured state, maybe alloyed with some Mg, which was not mixed in with the
thermite but simply poured as a layer on top of the charge, contained in a plastic pot that served simply as a disposable container. Initiation by
means of permanganate, sugar and ignition by a bit of glycerine. That failed to start with so a quick prod with the flame of a brazing torch was
employed, taking care to keep the gas line well WELL away from the reaction. Initiation was more or less instant. And when broken the chunks
themselves ignited and burned with an incandescent white flame that was hot enough to leave behind visual phosphenes.
Indeed even looked at slantways, that reaction was hot enough to leave coloured phosphenes before his eyes. This, whilst not, unlike these
compositions, explosive at all, reacted with the speed of a flashpowder type composition, liberating sufficient heat for the entire mass to glow white
hot, and the bits of metal left behind to autoignite when prodded with the metal end of a spade, leaving burns on the metal of the spades blade, the
blob/chunks of mixed metal/slag burning with a bright white flame, presume it was mixed iron/Al perhaps traces of Mg although with that being a thin
layer at the top one would have presumed it to have likely been consumed in an instant by the thermite charge placed beneath it, the Mg was sufficient
to be about a half inch deep over the top of the charge and a small amount of it pressed into a depression in the thermite.
So, it should, especially given the 300-500mesh size of it (300 I believe, the Al is the <3 micron particulate size powder) (the magnesium this is)
should, will have been ignited for certain and if it didn't partially melt and take part in the redox rxn itself, then it should easily have been
ignited, and partially thrown up a short distance into the air in particulate form, and should have been consumed instantly, should it not? there were
certainly an initial cloud of crackling white sparks before the thermite charge itself took, upon which it went off with a speed comparable to flash
powder (Al/chlorate or Al/pot perm or else Al/potassium nitrate) and a blinding, searing white flash, instantly reduced to a pile of glowing white and
in a few places, red hot slag, intermixed with metal of whatever alloy or description, which cannot precisely be described as molten but almost
granular due to admixture with alumina slag.
On their own, without oxidizer, just what is it likely to take to accidentally ignite in particular the aluminium, or the magnesium (less interested
in this because I know full well how flammable it is, but in the form of 300 mesh particulate dust its obviously going to be a LOT more reactive and a
lot easier to ignite and start fires. Which is not desired, generally speaking, the thermite reaction was just done on the 'yay postie just dropped
off his latest deliveries' principle, nice, shiny new chemicals to play with and to covet, in Tsath's gollum-ly manner
Not taking TOO much notice of the MSDS-es, because you know how MSDS sheets are. They always, always way overstate the dangers of things to the point
of utter uselessness. When the theoretical dangers that may under certain, restricted conditions occur if prodded hard enough into doing so, are made
to sound so utterly deadly they make dimethylmercury sound like babie's gripe water then its counterproductive IMO, because then people are likely
either/and to take any and all warnings as guff, and ignore them all, despite their being valuable information mixed in with the flatulent gibberings
and shriekings of terror and apocalyptic howlings of immanent worldly obliteration, or not even bother reading them. Hell, your average MSDS for say,
household concentration of aq.NH3, for distilled H2O, or NaCl often read like the devil his own self penned them in the blood of tortured sinners
mixed with water from the Styx, using a calligraphy brush carved from babies' bones and eyelashes ripped from kittens and bound thereto with glue
boiled down from the spines of such archons of generosity and kindliness as Mother Theresa. And whilst I myself have been hunched over the bench-top
since I was a kid, albeit starting out with little knowledge, and experimenting as the alchymists of yore, having very few and very old books of
theory to learn from, and growing steadily in knowledge and ability, my knowledge is by and large, autodidactic (including 'book learning' mind you,
and continued devouring of it, I do not just mean randomly combining reagents and seeing what happens, I just mean to state that there are gaps in my
knowledge, owing to my having to wrest the gems of delicious information from the morass of irrelevancy and of garbage. This is (and I will introduce
myself in whimsy if/when I am granted access to it, rather than here) but in short, its because my secondary school education was special ed (I'm
Kanner's/classically autie, or [ew ew ew ew ew] as [vomit] the likes of Autism Squeaks would word it 'severely' autistic', and didn't have the
opportunities that many in other schools must have had. I like, nay, more than 'like', absolutely love being 'severely' classically autie. It is a
gift, not a curse. Sure, a gift with a few annoying features at times, but not the neurotype analogue of a pair of woolen socks from a relative one
hates in the first place (wool...ew...just...*shudders* nasty...now thats one of the bad features)
Please do forgive my slightly long post here, it is the only one of its kind I intend, and because I have not access to whimsy, I wished to do a short
introduction (yes, for me, its short, I'm somewhat hyperlexic, although born severely dyscalculic and following an unfortunate incident involving
excitotoxicity and near fatality, have been left just shy of acalculic. So please, I humbly request, be patient when I screw up my math, or have
difficulty balancing equations. The latter of those two things I did not use to have, but following the excitotoxicity, and its been 12-14 years (cant
tell which, I haven't enough fingers to count on) since that awful and traumatic series of events, and only when on memantine have I been closer to
functional. I just ask that people here rather than launch into a verbal assault, explain, if they can take the time to do so, WHY and WHERE I erred.
For err I know I shall, and for people to know it is not merely from stupidity or worse, being owed to not really giving a shit and being a 'cookbook
chemist' of the anarchist's cookbook kind of slop-guzzling whorespawned level.
Hyperbolic, hypergolic, viral and chiral,
My laevo is on the right side.
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Chlorine
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If you're using the AL powder for thermite, a simple ball mill would work wonders, here's a video on the process;
https://www.youtube.com/watch?v=8rcrHotYico
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greenlight
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Just make sure you open the mill and expose it to the air periodically and don't open it and pour it straight out into another container letting it
fall through the air to prevent a lesson in pyrophoricity
Be good, otherwise be good at it 
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Dwarvensilver
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@ Toady,
Toady, I work with nearly 1000 chemicals and your comments crack me up ROFL! and you are correct they have me afraid to shake the saltshaker lol.
You Sir have a way with words.
I will have to try powdering some metals, I have a little double tumbler and have access to lots of ball bearings of different sizes.
I will look through the suggestions, Thanks all.
There is nothing more useless than doing well that which need not be done at all.
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UncleJoe1985
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aerosolize molten aluminum?
The problem with ball milling is it's too slow, noisy, and space intensive.
I have a crazy idea. Can you make Al powder by aerosolizing molten aluminum with one of those ultrasonic transducers that's used in mist generators
and for cleaning hard to reach places like inside fuel injectors?
Last summer, I had the idea of using those to make an evaporative/swamp cooler (no AC in my apartment).
I'm imagining for aluminum, I can melt a small batch using an induction heater. An ultrasonic transducer at the base would then turn on, creating tiny
high pressure bubbles that explode with huge force when they pop at the surface. Then you would blow the splashing aluminum away into a collection
chamber before they can fall back into the melt.
I don't know what frequency or power is needed. The ones used by mist generators use between 1 and 2 MHz and only a few watts at most. Aluminum is
much denser than water, so it must take a lot more power to cause cavitation.
I don't know if those piezo electric plates can survive being attached to a crucible at such high temperature. Also, no idea if what the particle size
will be.
[Edited on 28-11-2016 by UncleJoe1985]
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Tsjerk
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Why would those bubbles reach the surface?
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Metacelsus
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Of course, you'd have to do this under inert gas (argon).
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UncleJoe1985
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Crap, that was laughable to think I can use ultrasound to cause cavitation in molten Al. Al has an infinitesimally smaller vapor pressure than water
at its melting point (0.000012 Pascal vs 610 Pascal @ 0 C).
But apparently, it can be done according to here:
http://www.sciencedirect.com/science/article/pii/S0264127515307528
| Quote: | | As surface tension and vapour pressure at the melting point of Al are 0.871 N/m and 0.000012 Pa respectively [13], vapour bubbles are unlikely to be
formed in the bulk liquid Al. Thus, the majority of the cavitation bubbles in the liquid Al are considered to be pre-existing nuclei (e.g. solid
inclusions with absorbed hydrogen... |
So they're saying, the bubbles are from impurities.
Has anyone thought about producing powdered Al by atomization, like how it's done industrially?
I was thinking of melting aluminum by induction in some non-metal cruible. Then blasting it out of a nozzle at high pressure. According to some
sources, a pressure of 150 PSI and nozzle pore size of a few mm is good enough to produce particles of a few 100 microns.
http://www.mdpi.com/2075-4701/2/2/202/pdf
http://www.uobabylon.edu.iq/publications/applied_edition6/paper_ed6_3.doc
[Edited on 29-11-2016 by UncleJoe1985]
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symboom
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Chemically produced aluminum powder
Chloroethane or monochloroethane, commonly known by its old name ethyl chloride,
At various times in the past, chloroethane has also been produced from ethanol and hydrochloric acid, or from ethane and chlorine, but these routes
are no longer economical.
Excerpt
https://en.m.wikipedia.org/wiki/Chloroethane
Ethylaluminium sesquichloride
In the synthysis aluminum metal is produced
triethylaluminium can be produced from ethylaluminium sesquichloride by sodium reduction:
2 (C2H5)3Al2Cl3 + 3 Na → 3 (C2H5)2AlCl + Al + 3 NaCl
3 (C2H5)2AlCl + 3 Na → 2 (C2H5)3Al + Al + 3 NaCl
Of course this is very impractical
https://en.m.wikipedia.org/wiki/Ethylaluminium_sesquichlorid...
Zinc metal can be produced by disproportionate of zinc chloride with magnesium
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symboom
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Update brittle aluminum
http://www.alloyavenue.com/vb/showthread.php?8023-Amorphous-Aluminium-(-as-week-as-glass)
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Intergalactic_Captain
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I might be able to add a suggestion here - Years ago I experimented heavily with the "vortex" method using foil/chips/turnings/etc in blenders with
various liquids - Very minimal success, lots of burnt out blenders, oxides, and wasted time. So I just started buying aluminum for my pyrotechnic
purposes. Led to a catch-22 the other day, though, when I needed coarse Al for an experiment and I was afraid that 325 mesh, the coarsest on hand,
would be a bit too reactive.
So, instead of heavy-duty foil, I picked up the cheapest thinnest crap I could find. Four 25' rolls cut 1', layered, cut to 1" strips then cubes.
Instead of using a carrier liquid, I took a shot in the dark and tried dry-blending it. What I found is it's all in the technique;
Spun the blender up to it's highest speed, then tossed in a few of the cubes - after a few seconds there was a hovering "donut" of aluminum, to which
a few more handfuls were added until the vortex was about 2" deep over the airgap above the blades. This was blended until it reached about 50degC,
about what I was comfortable with pyrophoria-wise, then dumped and the next round started.
The result? Signifigantly smaller chunks and granules than I have ever had from any other method, and a decent amount of fine flakes already nearing
"flitter" grade. I'm planning on picking up a few dozen more rolls of this particular foil to experiment with, as I have the feeling that with proper
technique and loading this might be a promising technique for the not-quite-finest grades of Al powder, or at the very least a quick way of knocking
it down before milling.
If you see me running, try to keep up.
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Dr.Bob
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"aerosolize molten aluminum?"
People have been making various forms of aluminum dusts for years. There are many forms already available, and they include ball milled, aerosolized,
dusts, turnings, etc. There are quite a few people who have made their own ball milled Al, mostly for pyrotechnic applications (note that these may
be regulated by the ATF or CPSC due to use in explosives, sales are regulated.) So that is certainly doable, but the cost may be high if you just
need a little. You can buy a pound a year from some pyrotechnic chemicals companies.
Making your own aerosols might be pushing the DIY a bit, as while it is certainly possible, the costs and hazards of it would be harder to set up a a
small setup safely. Each type of Al dust has different uses, properties and hazards. The finer the powder, the more it can oxidize on the surface,
and if fine enough, that may oxidize a good bit of the material.
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