The main factors affecting spontaneous combustion of coal are:-
1. Coal rank, lower rank means more oxidation.
2. Temperature, oxidation doubles for every 10 degrees C rise.
3. Surface area of exposed coal, greater surface area increases the
oxidation.
4. Air flow, which must be sufficient to provide oxygen, but not to
reduce temperature.
5. Presence of easily oxidised material, such as timber, but also
pyrite. As pyrite oxidises it gives out a lot of heat and tends to crack
open the coal allowing a slow air flow. The ideal conditions for spon.
Com.
Barry Job.
-----Original Message-----
From: D.R.Poyner [mailto:[log in to unmask]]
Sent: 01 April 2003 13:36
To: [log in to unmask]
Subject: Re: Spontanious conbustion in coal mining tips
I discovered the extent of my ignorance a few weeks ago when I was asked
by a geologist to explain exactly why spontaneous combustion takes place
and was reduced to hand waving and vague talk of pyrites.
Can someone explain the role, if any, of sulphur containing compounds in
spontaneous combustion? Is their oxidation relevant to the process?
David Poyner
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