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A DSC study on the impact of low-temperature oxidation on the behavior and drying of water in lignite

  • Salman Khoshk Rish
  • Arash Tahmasebi
  • Jianglong YuEmail author
Article
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Abstract

Low-rank coals may undergo low-temperature oxidation and self-heating during mining, freightage, and handling. The oxidation of coal changes its structure which will be relected in the behaviour of coal water. A differential scanning calorimetry study was conducted to investigate the impact of low-temperature oxidation on the nature of water in a Chinese lignite and its drying behavior. The lignite sample was oxidized in the air at temperatures of 30–180 °C. The results showed that the lignite samples that underwent low-temperature oxidation did not contain any freezable bound water. It was found that the amount of non-freezable water in the oxidized samples reached the highest value of 67.38 mass% after oxidation at 80 °C. The Fourier transform infrared spectroscopy and the static sessile drop analysis results suggested that the concentration of oxygen functionalities and hydrophilicity of lignite samples peaked after oxidation at 80 °C, which in turn increased the tendency for the absorption of water as non-freezable water. It was also found that the types of water in the oxidized samples had a profound impact on its drying behavior, where free water showed higher drying rates compared with freezable bound water and non-freezable water. The coal sample pre-oxidized at 80 °C required higher energy for pre-drying compared with the raw coal, which was attributed to the higher proportion of non-freezable water after oxidation.

Keywords

Lignite Low-temperature oxidation Freezable water Non-freezable water DSC 

Notes

Acknowledgements

This study was supported by the National Natural Science Foundation of China (21476100 and 21676132).

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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2019

Authors and Affiliations

  1. 1.Key Laboratory of Advanced Coal and Coking Technology of Liaoning Province, School of Chemical EngineeringUniversity of Science and Technology LiaoningAnshanChina
  2. 2.Chemical EngineeringUniversity of NewcastleCallaghanAustralia

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