THERMAL SCIENCE

International Scientific Journal

Marko O. Obradović

,

Nikola V. Karličić

,

Dušan M. Todorović

,

Dejan B. Radić

,

Aleksandar M. Jovović

THE EFFECT OF MOISTURE CONTENT ON THE HARDGROVE GRINDABILITY INDEX OF COAL FROM THE KOLUBARA BASIN

ABSTRACT
In order to obtain data on the effect of moisture content on the grindability of coals, experimental research was conducted. The experiment included six samples of coal from the Kolubara basin. The samples were selected based on experimentally obtained values of their Hardgrove grindability index (HGI), in order to cover the entire range of experimental HGI values. In addition to determining the HGI, proximate, and petrographic analyses were performed on all samples. Lignites are naturally tough, soft, and greasy when in a moist state. By reducing the moisture content, lignites become more brittle. For this reason, Hardgrove grindability index values have different values depending on the moisture content at which they are determined. The HGI has a non-linear dependence on the moisture content of the coal. All curves have two inflection points, one minimum and one maximum value of Hardgrove grindability index in the tested range. The minimum values of HGI are in the range of 15-22% of the mass fraction of total moisture in coal, while the maximum values of HGI are for a total moisture content of 5-13%. In the case of high moisture content in coal, the obtained high values of HGI may not reflect the true grindability of the coal. These values could be misleading and not necessarily indicative of the coal inherent characteristics. Instead, they could be a result of the imperfections in the Hardgrove method used to determine the grindability index of coal with high moisture content.
KEYWORDS
coal, lignite, moisture, Hardgrove grindability index (HGI)
PAPER SUBMITTED: 2023-05-29
PAPER REVISED: 2024-01-15
PAPER ACCEPTED: 2024-05-22
PUBLISHED ONLINE: 2024-06-22
DOI REFERENCE: https://doi.org/10.2298/TSCI230529145O
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2024, VOLUME 28, ISSUE Issue 5, PAGES [4167 - 4174]
REFERENCES
  1. Radić, D. B., et al., A Study on the Grindability of Serbian Coals, Thermal Science, 15 (2011), 1, pp. 267-274
  2. Obradović, M. O., et al., Practical Assessment of Grinding Capacity and Power Consumption Based on Hardgrove Grindability Index and Coal Characteristics, Thermal Science, 23 (2019), Suppl. 5, pp. S1533-S1542
  3. Weigl, K., et al., Increasing Power Plant Efficiency by Fuel Drying, Computers and Chemical Engineering, 23 (1999), Suppl. 1, pp. 1-4
  4. Kakaras, E., et al., Computer Simulation Studies for the Integration of an External Dryer Into a Greek Lignite-Fired Power Plant, Fuel, 81 (2002), 5, pp. 583-593
  5. Jensen, E. J., Fryer, J. F., An Investigation of the Grindability of Alberta Subbituminous Coals, Mimeo-gruphed Circular No. 26, Research Council of Alberta, Edmonton, Alb., USA, 1958
  6. Novaković, L., Grindability Of Coal Matter (in Serbian), Mining Institute, Belgrade, 1976
  7. Azahari, H. L., The Effect of Moisture on the Grindability of Indonesian Coals, Master of Metallurgy (Hons.) Ph. D. thesis, Department of Materials Engineering, University of Wollongong, Wallongon, Australia, 1990, ro.uow.edu.au/theses/2590
  8. Lowry H. H., Chemisty Of Coal Utilization, Suplementary Volume, John Wiley & Sons, New York, USA, 1962
  9. Vuthaluru, H. B., et al., Effects of Moisture and Coal Blending on Hardgrove Grindability Index of Western Australian Coal, Fuel Processing Technology, 81 (2003), 1, pp. 67-76
  10. Yang, Y., et al., Effect of Moisture on Energy-Size Reduction of Lignite Coal in Hardgrove Mill, Fuel, 270 (2020), 117477
  11. Saramak, D., Kleiv, R. A., The Effect of Feed Moisture on the Comminution Efficiency of HPGR Circuits, Minerals Engineering, 43-44 (2013), Apr., pp. 105-111
  12. Obradović, M., Research and Comparison of the Influence of Low Rank Coals Characteristics on their Grindability and Milling Process Parameters (in Serbian), Ph. D. thesis, University of Belgrade Faculty of Mechanical Engineering, Belgrade, 2015
  13. Chelgani, S. C., et al., Prediction of Coal Grindability Based on Petrography, Proximate And Ultimate Analysis Using Multiple Regression and Artificial Neural Network Models, Fuel Processing Technology, 89 (2008), 1, pp. 13-20
  14. Hower, J. C., Interrelationship of Coal Grinding & Petrology, Minerals&Metallurgical Processing, 15 (1998), 3, pp. 1-16
  15. Hower, J. C., et al., Soft Modelling of the Hardgrove Grindability Index of Bituminous Coals: An Over-view, International Journal of Coal Geology, 247 (2021), 103846
  16. Sengupta, A. N., An Assessment of Grindability Index of Coal, Fuel Processing Technology, 76 (2002), 1, pp. 1-10
  17. Životić, D., et al., Petrological and Organic Geochemical Properties of Lignite from the Kolubara and Kostolac Basins, Serbia: Implication on Grindability Index, International Journal of Coal Geology, 131 (2014), Sept., pp. 344-362
  18. Jacob, H., Die Petrographische Bestimmung Das Xylitgehaltes Von Weichbraunkohlen, Geologisches Jahrbuch, Band 79 (1961), pp. 145-172
  19. Ercegovac, M., Micropetrographic Composition of Coal from Stanari with Special Emphasis on the Content of Xylite and Features of Briquetting, Buleltin of Mines, 28 (1989), pp. 28-37
PDF VERSION [DOWNLOAD]
The effect of moisture content on the Hardgrove grindability index of coal from the Kolubara basin

© 2024 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence