Sciencemadness Discussion Board

Turning Li metal blocks into powder

Fusionfire - 29-10-2011 at 02:27

Hello folks,

How would you turn lithium chips or ingots into a powder on a DIY scale/budget?

I am thinking that as the MP of Li is conveniently low (181C), one can melt it in a stainless steel vessel containing an inert atmosphere (e.g. He) and pressure inject it through an atomiser into a chamber also in an inert atmosphere. Desired particle size is anything under 100 microns.

To remove the Li powder you flush the chamber with paraffin oil and get a powder metal + oil slurry.

Does anyone know if this approach will work and if it does, how I come to suitable dimensions for the nozzle given molten Li's characteristics (viscosity, surface tension, desired particle size, etc.)

Thanks.

bbartlog - 29-10-2011 at 05:42

I'm not an expert on the techonology, but atomization of molten metal will probably require either pressurized gas (a stream of gas to break the liquid into tiny droplets) or else a rapidly spinning disk on to which the molten metal is dropped (tears the drops apart using centrifugal force). I'm not sure you can achieve the particle size you want just by pushing the molten metal through a nozzle.
However, given the low melting point of Li, I would think that if you have a solvent that it won't react with, you should be able to melt it with the solvent and then just atomize it by blending. Paraffin oil with bp around 200C?

Fusionfire - 29-10-2011 at 09:50

Thanks. I'm not an expert on the technology as well, but we all start from the beginning :)

BTW, I picked a stainless steel reaction vessel because Fe/C/Cr/V doesn't have any intermetallic reactions with Li AFAIK.

Fischer, S. H. and M. C. Grubelich (1996). A Survey of Combustible Metals, Thermites and Intermetallics for Pyrotechnic Applications. 32nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Lake Buena Vista, FL.
http://www.osti.gov/bridge/servlets/purl/372665-kjTA0r/webvi...

I can build two very fine nozzles (say bore diameter 80 ga or 0.343mm). One extrudes the liquid Li injected through it, and another arranged perpendicular to it blasts the molten Li stream with He or paraffin oil.

bahamuth - 29-10-2011 at 11:47

A Morton flask is used to create tiny beads of alkaline metal in a high bp solvent. Overhead stirrer is a must as I do nont think any magnetic strirrer will do..
Do not know if it will create particles as small as 100 µm though.

UnclearReactor - 30-10-2011 at 15:06

Spray nozzles have a unique geometry suited to the working fluid (viscosity, density, etc). For instance, the stream impinges on a something or is shaped like a pressure washer's or an airless paint sprayer's with a v-groove cut in it. Determining the geometry (which will change with the pressure) may be a daunting task. Or you might get lucky. The biggest hurdle is that you will have to ensure that the droplets don't coalesce before they freeze. Thermal stratification of the host fluid might work, but you will need a fluid lighter than lithum. Propane under pressure, maybe?

symboom - 6-11-2011 at 11:35

Vaporizing the metal is one way its up there in temperature wise is you have an oxy-fuel welder its no problem as temp reaches 6000F to heat the bottom of an inverted u shaped tube.
barium metal is produced by barium oxide and aluminum. barium vapor is condensed into a cooling chamber water jacket if you use dry ice in acetone or denatured alcohol as a cooling jacket it might be possable to flash solidify the lithium as a powder of course all done in a atmosphere of argon being the cheapest. as it is pyrophoric which makes this very dangerous in vaporized state 2448 °F is lithiums boiling point condensing it into kerosene or mineral oil sorrounded by dry ice cooling jacket

Sedit - 6-11-2011 at 12:50

Lithium nitride synthesis - US2910347

I can't remember the partical size it generated but it was fine enough so that Lithium and N2 reacted in good yields, the speed of stirring must be very high however. Replace N2 with argon in this case.

[edit]

Its stated the average particle size was slightly under 100microns.

[Edited on 6-11-2011 by Sedit]

Yamato71 - 5-12-2012 at 15:41

You might try grinding a mixture of dry ice and lithium metal in a coffee grinder until the metal is of the desired particle size. At the temperature of dry ice, the normally soft waxy metal becomes brittle and shatters like glass. Under a microscope, these fragments will be bright, jagged and crystalline, with a greatly increased surface area. Consequently, it will be more reactive, so you might want to add a bit of mineral oil or a spritz of WD-40 to the mix before grinding. You must then allow the dry ice to sublime by wrapping the coffee grinder in a towel and placing it in a freezer with the lid loosely in place. If you try to sublime the dry ice outside of a freezer, frost will form on the inside of the grinder and react with the lithium when it melts, possibly starting a fire. Let us know if this works.

elementcollector1 - 5-12-2012 at 15:57

Quote: Originally posted by Yamato71  
You might try grinding a mixture of dry ice and lithium metal in a coffee grinder until the metal is of the desired particle size. At the temperature of dry ice, the normally soft waxy metal becomes brittle and shatters like glass. Under a microscope, these fragments will be bright, jagged and crystalline, with a greatly increased surface area. Consequently, it will be more reactive, so you might want to add a bit of mineral oil or a spritz of WD-40 to the mix before grinding. You must then allow the dry ice to sublime by wrapping the coffee grinder in a towel and placing it in a freezer with the lid loosely in place. If you try to sublime the dry ice outside of a freezer, frost will form on the inside of the grinder and react with the lithium when it melts, possibly starting a fire. Let us know if this works.


Lithium is reactive with carbon dioxide....

Yamato71 - 5-12-2012 at 18:15

Not at -78c