Re: aluminum and water reaction

On 13 Nov 2003 01:39:06 -0800, [EMAIL PROTECTED] (shoprat) wrote:

>while tumbling some aluminum parts with water i came upon, what to me
>was
>a strange reaction.after taking the aluminum parts out of the
>tumbler,i poured
>the remaining water into a jar and tightened the cap. the next morning
>i noticed
>that a blackish-grey powder had fallen to the bottom,with clear water
>above
>it and a layer of similar colored powder floating on top of the water.
>when
>i picked up the bottle , small bubbles rose up through the water layer
>from the black powder on the bottom and the
>
> blackish-grey material on the top fell to the bottom of the jar.
> would someone explain this? could the particles on the bottom be
>finely powdered aluminum that reacted with the water to produce
>hydrogen gas
>bubbles?            
>                     regards,roger

yep.
i've had extensive experience with this process.  i used to work at a
factory that die cast Al parts with loose dies.  we had to roll the
parts to get off various amounts of flash.
they'd been doing this for, literally, 100 years.  
seeing that this process was developed so long ago, before the advent
of vibes, they would roll the parts in 3 ft^3 barrels with gravel.
after the process went for 8 hours, the parts would be rinsed off and
sent on for further manufacturing operations.
the resulting mud was sent into a trench where it was collected in a
large inground baffled tank.
about once per quarter, we'd call in a backhoe, get a 30 yd^3 dumpster
and dig out the tank.  after a period of time, the mud would set up
into a loose concrete.
anyway...

once the stuff was mixed by the backhoe, as it was shovelled into the
dumpster, the free Al would react over the course of the next day to
produce a huge volume of steam and hydrogen.  we had at least two
visits by the local Fire Dept after the locals called about dumpster
fires.

i never did get it to ignite.  i think in the open air, it never
reached the LEL.  technically, it wasn't a hazardous waste, because it
didn't meet the standard for ignitability, but no treatment operation
would accept it for disposal until the H2 and steam generation
stopped, which could take several days, especially in the winter.
when it was complete, it was concrete.

so short answer?  yep....