On Thu, 06 Aug 2009 09:04:36 +0000, Huge wrote:

On 2009-08-05, Tim Downie wrote:

"Andy Dingley" wrote in message
...
On 4 Aug, 17:51, Adam Aglionby wrote:
Obviously roofing grade concrete
http://www.youtube.com/watch?v=diZU4bfxrKw

Flour mill. They're always difficult to demolish, as they're so
strongly constructed. Must be one of the few buildings where you could
tip it on its side without it immediately self-dismantling under
gravity.

Just out of interest, why are flour mills so strongly constructed?
Presumably all that strength costs money and isn't done without good reason.

http://en.wikipedia.org/wiki/Grain_dust_explosion

Belated thanks for that! It got me reading about the Washburn mill
explosion, which was somewhat on local turf - and I happened to be down in
St. Paul for the last few days, so hopped over to Minneapolis and took a
wander around the mill museum which is on the Washburn site now.

Fantastic museum, anyway - and they do a nice little demo of a dust
explosion using a model mill, 'dust' (I suspect it was regular houshold
flour), and an ignition source.

One interesting snippet of info was that a lot of these big explosions
aren't caused just by dust naturally circulating in the air. That often
only creates a small fire / flash, but results in caked dust being
dislodged from equiment, vents etc. - and it's that which provides the
fuel for the main event (hence such sites not only have to be kept free of
dust in the air, but equipment has to be constantly cleaned to avoid any
build-up of material)

cheers

Jules