Effects of Water and Brine Saturation on Mechanical Property Alterations of Brown Coal

Xiaogang Zhang, Ranjith Pathegama Gamage, Mandadige Samintha Anne Perera and Ashani Savinda Ranathunga
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Xiaogang Zhang: Deep Earth Energy Research Laboratory, Building 60, Monash University, Melbourne, VIC 3800, Australia
Ranjith Pathegama Gamage: Deep Earth Energy Research Laboratory, Building 60, Monash University, Melbourne, VIC 3800, Australia
Mandadige Samintha Anne Perera: Deep Earth Energy Research Laboratory, Building 60, Monash University, Melbourne, VIC 3800, Australia
Ashani Savinda Ranathunga: Department of Civil Engineering, University of Moratuwa, Moratuwa 10400, Sri Lanka

Energies, 2018, vol. 11, issue 5, 1-17

Abstract: The adsorption of moisture or brine into coal causes the coal mass mechanical properties to be significantly altered, which can greatly affect the coal mining and coal seam gas extraction process. A study was therefore initiated to investigate the influence of moisture and brine saturations (5–25%) on brown coals’ strength through a series of unconfined compressive strength tests, with the aid of acoustic emission, optical 3-D deformation analysis and scanning electron microscopy. According to the results, the coal mass is weakened by up to 26% upon the adsorption of moisture and water saturated samples show no crack propagation, whereas brine saturation enhances coal strength by up to 21% and delays crack propagation due to the crystallization of sodium chloride. Besides, a high brine concentration (25%) greatly improves coal mass strength but impairs the increase of Young’s modulus due to its corrosive nature, which is consistent with the values of maximum strain at failure of the tested samples (3.9%, 3.1% and 3.6% for 5%, 15% and 25% brine saturated samples, respectively). In addition, because of the precipitation of sodium chloride in coal and the increase of conductivity of pore fluid, more acoustic emission signals are detected for brine saturated samples, while water saturated samples exhibit mush less acoustic release compared to the unsaturated samples.

Keywords: brown coal; mechanical properties; water saturation; brine saturation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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