A comparative study of coals of different ranks having different chemical structure and petrography would be desirable to gain an in-depth knowledge of Indian coals. Here, we report structural and petrographic analyses of three different coals: Coal A (coking coal), Coal B (semi-coking coal) and Coal C (non-coking coal) of Indian origin. The vitrinite reflectances of the three coals were measured to be 1.26, 1.38 and 0.46 for Coal A, Coal B and Coal C, respectively. Size fractionation (− 3.0 + 1.0 mm, − 1.0 + 0.5 mm and − 0.5 mm) followed by density gradient separation (1.2, 1.3, 1.4, 1.6, 1.8 g/cm3) were performed for all the coal samples to study mineral matter liberation and distribution of macerals in different density fractions. Petrographic analysis of different density fractions revealed a direct proportionality of vitrinite content to swelling properties. The highest free-swelling indices (7.5 and 6.5) were observed for 1.2 density fraction of Coal A and Coal B, respectively. Fourier transform infrared spectroscopy revealed crucial information relating the degree of aromaticity and aliphaticity with observed coking properties. Specifically, aromaticity (AR1) (CHar stretching/CHal stretching, (3000–3100 cm−1)/(2800–3000 cm−1) and mean reflectance (Ro in %) were found to have a strong positive linear correlation with each other, indicative of an increase in aromaticity with coal rank.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
ASTM D388–12. (2012). Standard classification of coals by rank. Pennsylvania: ASTM International.
ASTM D-720/D720M-15. (2015). Standard test method for free-swelling index of coal. Pennsylvania: ASTM International.
BIS IS 1350-1. (2003). Methods of test for coal and coke, part I: Proximate analysis (2nd revision). New Delhi: Bureau of Indian Standards.
BIS IS 1353. (1993). Methods of test for coal carbonization–caking index, swelling number and (LT) Gray-King assay. New Delhi: Bureau of Indian Standards.
Carlson, G. A. (1992). Computer simulation of the molecular structure of bituminous coal. Energy & Fuels,6, 771–778.
Chen, Y., Mastalerz, M., & Schimmelmann, A. (2012). Characterization of chemical functional groups in macerals across different coal ranks via micro-FTIR spectroscopy. International Journal of Coal Geology,104, 22–33.
Clarence, K., Jr. (1978). Analytical methods for coal and coal products (Vol. 1). New York: Academic Press.
Cody, G. D., Davis, A., & Hatcher, P. G. (1993). Physical structural characterization of bituminous coals: Stress–strain analysis in the pyridine-dilated state. Energy & Fuels,7, 455–462.
Ganz, H., & Kalkreuth, W. (1987). Application of infrared spectroscopy to the classification of kerogentypes and the evaluation of source rock and oil shale potentials. Fuel,66, 708–711.
Ghosh, A., & Chatterjee, A. (2008). Iron making and steel making: Theory and practice (pp. 142–144). New Delhi: Prentice-Hall of India Private Limited.
Holuszko, M. E., & Mastalerz, M. D. (2015). Coal maceral chemistry and its implications for selectivity in coal floatability. International Journal of Coal Preparation and Utilization,35, 99–110.
Hower, J. C., & Eble, C. F. (1996). Coal quality-coal utilization link often ‘understated’ in discussions. National Coal Leader,30(5), 12.
Ibarra, J., Muñoz, E., & Moliner, R. (1996). FTIR study of the evolution of coal structure during the coalification process. Organic Geochemistry,24, 725–735.
Iglesias, M. J., Jimenez, A., Laggoun-Defarge, F., & Suarez-Ruiz, I. (1995). FTIR Study of pure vitrains and associated coals. Energy and Fuel,9, 458–466.
Iino, M., Takanohashi, T., Ohsuga, H., & Toda, K. (1988). Extraction of coals with CS2-N-methyl-2-pyrrolidinone mixed solvent at room temperature: Effect of coal rank and synergism of the mixed solvent. Fuel,67, 1639–1647.
International Committee for Coal and Organic and Petrology ICCP. (1998). The new vitrinite classification (ICCP System 1994). Fuel,77, 349–358.
International Committee for Coal and Organic and Petrology, ICCP. (2001). The new inertinite classification (ICCP System 1994). Fuel,80, 459–471.
Larsen, J. W., Gurevich, I., Glass, A. S., & Stevenson, D. S. (1996). A method for counting the hydrogen-bond cross-links in coal. Energy & Fuels,10, 1269–1272.
Larsen, J. W., Lee, D., & Shawver, S. E. (1986). Coal macromolecular structure and reactivity. Fuel Processing Technology,12, 51–62.
Lis, G. P., Mastalerz, M., Schimmelmann, A., Lewan, M. D., & Stankiewicz, B. A. (2005). FTIR absorption indices for thermal maturity in comparison with vitrinite reflectance R0 in type-II kerogens from Devonian black shales. Organic Geochemistry,36, 1533–1552.
Marzec, A. (2002). Towards an understanding of the coal structure: a review. Fuel Processing Technology,77–78, 25–32.
Mastral, A. M., Mayoral, M. C., Rivera, J., & Maldonado, F. (1997). New approach to coal structure through its evolution during dry catalytic hydrogenation. Energy & Fuels,11, 483–490.
Mathews, J. P., & Chaffee, A. L. (2012). The molecular representations of coal—A review. Fuel,96, 1–14.
Meyer, R. A. (1982). Coal structure. New York: Academic Press.
Miller, B. G. (2005). Coal energy systems. Burlington: Elsevier Academic Press.
Mishra, V., Sharma, M., Chakravarty, S., & Banerjee, A. (2016). Changes in organic structure and mineral phases transformation of coal during heat treatment on laboratory scale. International Journal of Coal Science and Technology,3, 418–428.
Mohanty, A., Chakladar, S., Mallick, S., & Chakravarty, S. (2019). Structural characterization of coking component of an Indian coking coal. Fuel,249, 411–417.
Nakamura, K., Takanohashi, T., Iino, M., Kumagai, H., Sato, M., Yokoyama, S., et al. (1995). A model structure of Zao Zhuang bituminous coal. Energy & Fuels,9, 1003–1010.
O’Brien, G., Firth, B., & Adair, B. (2011). The application of the coal grain analysis method to coal liberation studies. International Journal of Coal Preparation and Utilization,31, 96–111.
Oikonomopoulos, I. K., Perraki, M., Tougiannidis, N., Perraki, T., Frey, M. J., Antoniadis, P., et al. (2013). A comparative study on structural differences of xylite and matrix lignite lithotypes by means of FT-IR, XRD, SEM and TGA analyses: an example from the Neogene Greek lignite deposits. International Journal of Coal Geology,115, 1–12.
Riley, J. T. (2007). Routine coal and coke analysis: collection, interpretation, and use of analytical data (pp. 84–92). Pennsylvania: ASTM International.
Sakimoto, N., Takanohashi, T., Harada, Y., & Fujimoto, H. (2014). Relationship between chemical structure of caking additives produced from low rank coals and coke strength. ISIJ International,54, 2426–2431.
Smędowski, L., & Krzesin´ska, M. (2013). Molecular oriented domains (MOD) and their effect on technological parameters within the structure of cokes produced from binary and ternary coal blends. International Journal of Coal Geology,111, 90–97.
Solomon, P. R., & Carangelo, R. M. (1988). FT-IR analysis of coal: 2 Aliphatic and aromatic hydrogen concentration. Fuel,67, 949–959.
Solum, M. S., Pugmire, R. J., & Grant, D. M. (1989). Carbon-13 solid-state NMR of Argonne-premium coals. Energy & Fuels,3, 187–193.
Speight, G. J. (1994). The chemistry and technology of coal. Berkeley, California: CRC Press.
Speight, G. J. (2005). Hand book of coal analysis. Chichester, England: Wiley.
Stach, E., Mackowsky, M. T., Teichmüller, M., Taylor, G. H., Chandra, D., & Teichmüller, R. (1982). Stach’s textbook of coal petrology (3rd ed.). Berlin: Borntraeger.
Stanger, R., Tran, Q. A., Attalla, T., Smith, N., Lucas, J., & Wall, T. (2016). The pyrolysis behaviour of solvent extracted metaplast material from heated coal using LDI-TOF mass spectroscopy measurements. Journal of Analytical and Applied Pyrolysis,120, 258–268.
Suárez-Ruiz, I., & Crelling, J. C. (2008). Applied coal petrology. Amsterdam: Elsevier.
Takanohashi, T., & Masashi Iino, M. (1990). Extraction of Argonne premium coal samples with carbon disulfide-N-methyl-2-pyrrolidinone mixed solvent at room temperature and ESR parameters of their extracts and residues. Energy & Fuels,4, 452–455.
Wang, S. H., & Griffiths, P. R. (1985). Resolution enhancement of diffuse reflectance IR spectra of coals by Fourier self-deconvolution: 1. C–H stretching and bending modes. Fuel,64, 229–236.
Wu, D., Liu, G., Sun, R., & Xiang, F. (2013). Investigation of structural characteristics of thermally metamorphosed coal by FTIR spectroscopy and X-ray diffraction. Energy & Fuels,27, 5823–5830.
Zhang, L., Hower, J. C., Liu, W., & Men, D. (2016). Maceral liberation and distribution of bituminous coal for predicting maceral separation performance. International Journal of Coal Preparation and Utilization,37, 237–251.
The authors are thankful to the Director, National Metallurgical Laboratory for permission to publish this work. The work is the part of the ongoing project sponsored by Tata Steel Ltd, Jamshedpur, India. The authors also wish to thank anonymous learned reviewers for their critical evaluation and valuable suggestions to improve the quality of paper.
About this article
Cite this article
Chakravarty, S., Chakravarty, K., Mishra, V. et al. Characterization of Chemical Structure with Relative Density of Three Different Ranks of Coal from India. Nat Resour Res (2020). https://doi.org/10.1007/s11053-020-09629-z
- Indian coal
- FT-IR spectroscopy
- Swelling index
- Coal rank