reply to post by kattraxx
I tell ya, the idea that coal could undergo auto-ignition just from the sun shining on it was something new for me. It was new because it's frankly
The full text of the original news report may be found here,
and the follow-up story
alleging auto-ignition due to sunlight can be accessed on
As the firefighter commented, the sun can produce ground temperatures of up to say 160 degrees F, which is something I did know, having grown up in a
pretty warm part of Australia.
However, 160 F is nowhere near hot enough to make coal auto-ignite. (Auto-ignition means that a substance starts
burning without the application of an external source of ignition such as a flame or spark, but purely from the heat in its surroundings.)
Semi-anthracite coal will auto-ignite at 752 F, charcoal at 660 F. So even if it's charcoal dust we're about 500 deg. F. below the required
Here's an engineering website that shows a table listing auto-ignition
temperatures for several substances.
A few other points that indicate the experts' story is not acceptable:
The scene was attended and secured by firefighters. One would think that they would recognize burning coal? It has an unmistakable aroma, and in
addition, it gives off gases, some of which are hazardous. The report stated
Tests by hazmat team members show there are no dangerous
I also know from my own experience with our coal-burning stove in the cottage that coal produces smoke. Are we to believe that this coal dust is
burning away, but no smoke is being produced? And no toxic gases either? I mean, the report indicates the coal dust is on the surface of the ground,
not buried way beneath it:
"What the state representatives indicated to us is that the coal spoil that's been on top of the ground for years and years reacts with the
sun, heat of the sun and it spontaneously combusts.”
So it's been sitting there for "years and years", but the Fire Battalion Chief says:
"In my twenty-four years I haven't witnessed this
kind of occurrence. So it's unique.”
Really, not even in high summer? Which it isn't there right now? Not once in nearly a quarter of a century?
One other point on this matter: if the sun was hot enough to make coal auto-ignite, then it was also hot enough to make dry wood do the same. This is
reported to be a park area (and a look on google earth confirms that there is park area of that name in that region)...And in parks, there are often
benches and other wooden articles like fence posts and signs, and also dead wood from trees. Research has shown that wood can auto-ignite at
temperatures of around 250 Celsius (482 F). Reference: an abstract from the Journal of Fire
So how come the local dead wood and benches etc have not also spontaneously ignited? Well it's lucky for the locals they didn't, hey? Especially as
the locals would be literally done to a turn if the sun were beating down with a temperature of well over 600 degrees F. I mean, you cook a roast at
less than that!
In summary, the statement that this coal dust, lying on the surface for years, spontaneously ignited due to the action of sunlight alone, is absurd.
However, a look at the map below might give a clue:
(This image has been reproduced from the Colorado Geological Survey website and is used under fair-use conditions for informational and educational
purposes. The complete page including this image may be accessed here.
The park in question is due north from the Thirty-Nine Mile Volcanic Field. It is not
, as far as I can determine, over it. However, with
seismic activity being the semi-mystery that it is, I do not think we can rule out some kind of volcanic cause for this 800-degree region of land;
there is a volcanic field in the general vicinity and this makes it more likely than if there were none. It could also be that a coal seam below the
area has ignited -- for such cases have been known before -- and that
could cause the rise in ground temperature. However in that case one
would expect that hazmat experts would detect evidence of burning coal. They say they haven't detected any dangerous gases and burning coal
produces dangerous gases
....I think we're not getting the whole story...
Edited to fix some glitches so all the links will work, and to add a few more lil' comments.
[edit on 8-6-2008 by JustMike]