CAO YUNXING, Jiaozuo Institute of Technology, Henan 454159, China, and LIU RUIXUN, Department of Geology, Peking University, Beijing 100871, China
Deformed coal is called tectonic coal which is further classified as
cataclastic coal, granular coal, and mylonite coal. All three kinds of
tectonic coal have generated dynamometamorphism during their deformation
period. Compared with normal coal, their physical and chemical properties
changed:
1) The basic structure unit (BSU) of tectonic coal increased. Compared
to bituminous coal, the Lc of BSU of the tectonic coal increases while
La stays constant. Compared to anthracites, La of BSU of tectonic coal
increases while Lc stays constant.
2) The free radical content of bituminite in the tectonic coal is higher
than that of normal coal. The free radical content of meta-anthracitic
tectonic coal is decreased.
3) The reflectence and hydrcarbon content of tectonic coal is increased.
All of above facts suggest that the physical and mechanical properties
of tectonic coal was changed by structural stress during the geological
history. This kind of change is called deformation metamorphism or dynamometamorphism
of coal.
Our studies show that the zone with tectonic coal will have a propensity
for gas and coal outbursts and spontaneous combustion. Geologists and mining
engineers of China consider tectonic coal as a useful indicator used for
forcasting outburst zone and dangerous zone of spontaneous combustion of
coal.
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