D. S. PATTANAIK ET AL.
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2.9. Correlation Co-Efficient for Exinite and
CPT
Correlation between exinite and CPT has been shown in
Figure 6. The calculated value of t was found to be 3.
6381 and the tabulated value for t is 2.1448, hence sig-
nificant.
2.10. Correlation Co-Efficient for Inertinite and
CPT
Correlation between inertinite and CPT was drawn in
Figure 7. The calculated value of t was found to be
3.9157 and the tabulated value for t is 2.1448, hence sig-
nificant.
3. Conclusions
From the foregoing discussions, the following conclu-
sions are drawn.
1) Unlike other lower Gondwana coalfields, the Chiri-
miri coalfield is located in a different physiographic set
up, i.e., at an elevation of 650 m from MSL.
2) The degree of proneness to spontaneous combustion
of the coals is related to stratigraphy or rank of the coal
which was proved by the study of different parameters.
3) The study of volatile matter and crossing point tem-
perature reveal that the Chirimiri coals are moderate to
highly prone to spontaneous combustion.
4) Petrographic study proves that the degree of prone-
ness to spontaneous combustion increases with the in-
crease of vitrinite and exinite, but decreases with the
increase of inertinite content.
5) Infrared studies prove that the top Duman and
Kaperti seam coals show stronger absorbance than the
coals of other seams. Hence, these seams are relatively
more prone to spontaneous combustion as compared to
the bottom Karakoh and Sonawani seams.
6) The DTA studies used to assess the spontaneous
combustibility character show that the first endothermic
peak temperature range for Karakoh and Sonawani
seams is 104˚C to 116˚C whereas that for Kaperti and
Duman seams is 100˚C to 106˚C. Hence, the Kaperti and
Duman seam coals are highly prone to spontaneous
combustion.
7) Correlation co-efficients of CPT with DTA, CPT
with vitrinite, CPT with exinite and CPT with inertinite
were found to be significant. Therefore, lower the CPT,
higher is the tendency to spontaneous heating suscepti-
bility.
8) All parametrical tests suggest that the proneness to
spontaneous heating is related to the rank of coal.
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