1. C LASSIFICATION OF COAL By Satyajit Rout

2. T ERMS USED V(VM) : volatile matter content C : Carbon content A : ash content M : moisture content O: oxygen N: nitrogen H: hydrogen, S: sulfur daf: dry ash free basis dmmf: dry mineral matter free basis BTU: British thermal unit

3. C LASSIFICATION AND ITS OBJECTIVE Classification means classifying or categorising objects as per their characteristics or property. Objective is to place like things together and separate things that differs.

4. C LASSIFICATION OF COAL Coal is a naturally available heterogeneous organic mass. So very difficult to classify. Hence for last 150 years many attempts have been made. Since then many system of classifications have classified coals according to different classification basis. Followings are examples of such classification system.

5. C LASSIFICATION BY VISUAL CHARACTERS CategoryAttributesFlame Brown coal/ligniteBrown colour, woody structure ---------------- Bituminous coalBlack and bandedSmoky yellow flame AnthraciteBlack and lustrousBurns without flame

6. C LASSIFICATION BASED ON THEIR SOURCE OF GENESIS : H UMIC AND SAPROPELIC COAL Humic coal: Those developed from terrestrial plant debris that was exposed to atmosphere and passed through peat stage Higher plant kingdom is source Sapropelic coal: Developed from plankton, algae, terrestrial plant but in anaerobic or Lacustrine condition. E.g. bog head coal, cannel coals

7. C LASSIFICATION BY ULTIMATE ANALYSIS : 1. R EGNAULT -G RÜNER -B ROSQUET SYSTEM First attempt in 1837 Based on the C, H, O content Only includes coal with more than 75% carbon on d.a.f basis. Initially Regnault gave a system considering only O+N but later modified

8. Classification table of Regnault-Grüner-Brosquet system

9. 2. S YLER ’ S CLASSIFICATION The complete system was published in 1899 %age of C, N, O and H is considered in dry ash sulfur free basis His classification divided coal into 7 carbon planes and 2 hydrogen planes. The 7 carbon planes are  Anthracite (>93.3% C)  Carbonaceous (91.2-93.3% C )  Bituminous 1. Meta(91.2-89% C) 2. Ortho(87-89% C) 3. Para (84-87% C)

10. S EYLER ’ S CLASSIFICATION ( CTD …)  Lignitous 1. Meta (80-84% C) 2. Ortho (75-80% C) Hydrogen planes 1. Per- hydrous(>5.8% of H) 2. Sub hydrous(< 4% of H) Disadvantages Complex naming Inadequate classification for low rank coals Applicable only to British Carboniferous Coal

11. S EYLER ’ S CHART

12. 3. G ROUT AND R ALSTON CLASSIFICATION In 1907 Grout plotted C, H, O contents of American Coal on a tri-axial diagram. The plot separated cannel coal(high H) from ordinary coal Classification was based on dry-ash free analysis including fixed C and Total C In1915 Ralston extended the study and found coal of equal Volatile matter(isovols) and equal calorific value(isocals) can be represented by straight lines in the triangle.

13. C LASSIFICATION BASED ON PROXIMATE ANALYSIS Moisture, volatile matter, ash, fixed carbon content play the role of criteria “fuel ratio” which is fixed carbon/volatile matter is used most 1. Roger’s classification:  in 1858 he divided coals into 4 groups on basis of %age V, M,Ash.

14. C LASSIFICATION BASED ON PROXIMATE ANALYSIS 2. Frazer’s classification:  In 1877, he used fuel ratio to classify coal as given:  Coals of lower rank than bituminous were not considered  Study was on only Pennsylvania coal. Sl noCoal typeFuel ratio 1.Anthracite100-12 2.Semi anthracite8-12 3.Semi bituminous5-8 4.Bituminous0-5

15. C LASSIFICATION BASED ON PROXIMATE ANALYSIS 3. Campbell classification:  also based on fuel ratio but all coals below 5 FR were taken as bituminous coal  In 1926, he combined fuel ratio to different characteristics for distinguishing lower rank coal. Sl no.Coal typefuel ratio 1.Anthracite10-50 2.Semi anthracite5-10 3.Semi bituminous2.5-5 4.Bituminous<2.5

16. C LASSIFICATION INVOLVING BOTH PROXIMATE ANALYSIS AND CALORIFIC VALUE : 1. Parr’s classification: He considered Volatile Carbon, Total Carbon, inert volatile matter and gross coal index(C+ available H+ S) The basis was Volatile carbon X 100/Total carbon. He gave a new classification in 1928, where he used following formula (indicated BTU-50S) X100 Unit B.T.U=--------------------------------------- 100-(1.08A +0.55S)

17. P ARR ’ S CLASSIFICATION [V as determined-(0.8A+0.4S)]X 10 unit VM=------------------------------------------------ 100-(1.08A +0.55S) Class% unit VMUnit BTU Anthracite0-815000-16500 semi Anthracite8-1215000-16500 Bituminous A12-2415000-16500 Bituminous B25-5015000-16500 Bituminous C30-5514000-15000 Bituminous D35-6012500-14000 Lignite35-6011000-12500 Peat55-809000-110000

18. A.S.T.M. C LASSIFICATION It classifies coal to 4 broad classes based on fixed carbon and calorific value (BTU) on dry mineral matter free basis. Applicable only to vitrinite rich coal and excludes southern Gondwanaland coal Gross Heating Value found on a moist and mineral matter free basis. Moist refers to the natural inherent water contained (MJ/kg X 430.11=Btu/lb). Coals containing 69 wt % or more fixed carbon on a dry mmf basis are ranked according to their fixed carbon content regardless of their Gross Heating Value.

20. C LASSIFICATION BY N ATIONAL C OAL B OARD Specifically designed for commercial use Rank based Uses 3 digit code to identify main class, class and subclass to which a coal belongs Applicable to vitrinite rich coal Volatile matter in dmmf basis and Gray-King coke type values are considered.

21. Class Volatile matter 1) (weight %) General description 101< 6.1 Anthracites 1023.1 - 9.0 2019.1 - 13.5Dry steam coals Low volatile steam coals 20213.6 - 15.0 20315.1 - 17.0Cooking steams coals 20417.1 - 19.5 20619.1 - 19.5Heat altered low volatile steam coals 30119.6 - 32.0Prime cooking coals Medium volatile coals 30519.6 - 32.0 Mainly heat altered coals 30619.6 - 32.0 40132.1 - 36.0 Very strongly coking coals High volatile coals 402> 36.0 50132.1 - 36.0 Strongly coking coals 502> 36.0 60132.1 - 36.0 Medium coking coals 602> 36.0 70132.1 Weakly coking coals 702> 36.0 80132.1 - 36.0 Very weakly coking coals 802> 36.0 90132.1 - 36.0 Non-coking coals 902> 36.0

22. I NTERNATIONAL CLASSIFICATION OF HARD COAL Mainly for anthracites and bituminous coal but covers fairly all kinds Uses 14 digit code that defines 8 parameters namely 1. vitrinite reflectance 2. Reflectogram characteristics 3. Inertinite content 4. Exinite/liptinite content 5. Caking property(FSI) 6. 2 for VM 7. 2 for Ash 8. 2 for S 9. 2 for gross calorific value

23. C LASSIFICATION OF I NDIAN C OAL Scientific Coding of Indian Coal 3 basic parameters and 1 supplementary parameter 1 st digit (1-9) corresponds to Calorific value (dmmf) 2 nd (0-9) one Volatile matter (dmmf) 3 rd (0-5)one Coke type 4 th (1-6) one: Maximum thickness of plastic layer for Caking coal and M % for non caking.

24. G RADING OF I NDIAN C OAL For grading of Non-Coking coal useful heat value is used, which is calculated by HU= 8900- 138(ash + moisture) kcal/kg 1. if M<2% and VM< 19% then deduct 150 kcal/kg for each 1% reduction in VM 2. M at 40 c and 60% RH Grading does not include coal from North East India Grading of coking coal is done as per their ash content

25. G RADING OF N ON - C OKING C OAL GradeUseful heat value(kcal/kg) A>6200 B5601-6200 C4941-5600 D4201-4940 E3361-4200 F2401-3360 G1301-2400

26. G RADING OF C OKING C OAL GradesAsh content Steel I<15% Steel II15-18% Washery grade I18-21% Washery grade II21-24% Washery grade III24-28% Washery grade IV28-35% Semi coking I<19%(A+M) Semi coking II19-24%(A+M) Hard coke by product premium<25% Ordinary25-30% Beehive premium<27% Beehive superior27-31% Beehive Ordinary32-36%

27. C LASSIFICATION FOR EXPORT PURPOSE GradeLow volatileHigh volatile Selected 7000 cal 6800 cal First 6500 cal 6300cal Second 6000 cal Third---------------------------------------------------

28. R EFERENCE Sarkar S. (1988), “Fuels and Combustion”, Orient Longman Publication, 2 nd edition, pp-71-85 Rose H.J.(1945),“Chemistry of Coal Utilisation”, John Wiley & Sons, Vol. I, pp 25-80 Berkowitz N (1994), “An Introduction to Coal Technology”, Academic Press, 2 nd edition, pp-61- 72 “Classification and Codification of Indian Coals and Lignite”, IS:770-1977 Krishnan M.S. (1940), “Classification of Coal”, Vol. III

29. T HANK YOU