| COAL
QUALITY The quality of Indian coal is mainly attributed
to its origin. Due to drift origin of Indian coal, inorganic impurities are intimately
mixed in the coal matrix, resulting in difficult beneficiation characteristics.
Over 200 million tonnes of coal reach the consumers with ash content averaging
40 percent. Based on ash content, gross calorific value and useful heat value,
Indian coal is classified in six categories as given in Table 4. Table 4
: Grading and Quality of coal
| Grade |
(Ash + Moisture % ) Approx. |
Useful heat value(UHV) (Kcal./Kg)
| | A |
19.5 or less | Above
6200 | | B |
24-19.5 | 5600-6200
| | C |
28.7-24 | 4940-5600
| | D |
34-28.7 | 4200-4940
| | E |
40-34 | 3360-4200
| | F |
47-40 | 2400-3360
| | G |
55-47 | 1300-2400
| Sulphur content in Indian coal is generally less than 0.6
percent and the Chlorine content is less than 0.1 percent. Mercury in coal ranges
from 0.01 to 1.1 ppm in Indian coals against upto 20 ppm in Russian coals, 0.2
to 2.0 ppm in Belgium coals, 0.03 to 1.3 ppm in Canadian coals and 0.01 to 2.0
ppm in American coals. ( Source : Mishra et.al.(1997) "Clean coal
technolgy – Indian context"; Indo-European Seminar on Clean coal technology, New
Delhi) | 
