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Journal of Thermal Analysis and Calorimetry

, Volume 137, Issue 6, pp 2007–2016 | Cite as

Wettability modification and flotation intensification of low-rank coal with dodecyltrimethylammonium chloride addition

  • Kunkun Zhen
  • Haijun ZhangEmail author
  • Changlong Zheng
Article
  • 55 Downloads

Abstract

The surface free energy of mineral particles is a key factor affecting the bubble–particle attachment and mineralization process. In this study, the free surface energy was calculated in order to clarify the interaction mechanism between low-rank coal and dodecyltrimethylammonium chloride (DTAC) from the perspective of thermodynamics. Additionally, wetting heat was employed in order to reveal the change in the surface wettability of long-flame low-rank coal with different DTAC additions, i.e. 0, 15, 30, 45, and 60 g t−1. The wetting heat of long-flame low-rank coal gradually became less negative with the increase in the DTAC dosage, which indicated that the hydrophilicity of the low-rank coal’s surface was effectively restrained, corresponding to enhanced hydrophobicity. Furthermore, the effect of DTAC on the attachment time (induction time) between the coal particles and bubbles was investigated. The results illustrated that the attachment time between the coal particles and the bubbles decreased from 180 to 30 ms as DTAC dosage increased (DTAC dosage of 0–60 g t−1). That is, the attachment time decreased by up to 83.33% over the investigated range of DTAC dosages; this dynamic was consistent with the results of the calculation of the surface free energy and the measurement of the wetting heat. The mean zeta potentials became less negative with the DTAC addition in the presence and absence of diesel oil. Consequently, DTAC enhanced the flotation performance of long-flame low-rank coal in a flotation system; furthermore, the combustible recovery was significantly enhanced (by up to 11.29% points) and the concentrated ash value was less enhanced (by up to 0.20% points) as the DTAC dosage increased up to 60 g t−1.

Keywords

Low-rank coal DTAC Surface free energy Wetting heat Bubble–particle attachment 

Notes

Acknowledgements

The authors would like to acknowledge financial support from the Fundamental Research Funds for the National Natural Science Foundation of China (No. 51722405) and the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).

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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2019

Authors and Affiliations

  1. 1.Chinese National Engineering Research Center for Coal Preparation and PurificationChina University of Mining and TechnologyXuzhouChina
  2. 2.School of Chemical Engineering and TechnologyChina University of Mining and TechnologyXuzhouChina

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