Influence mechanism of fatty acid unsaturation on the intensification of low-rank coal flotation

XU Meng-di; HE Lin; SI Wei-han; BAO Xi-cheng; LIU Xiao-kang; XING Yao-wen; GUI Xia-hui; CAO Yi-jun

doi:10.13374/j.issn2095-9389.2021.10.26.001

Volume 45 Issue 2

Feb. 2023

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Article Navigation > Chinese Journal of Engineering > 2023 > 45(2): 195-205

XU Meng-di, HE Lin, SI Wei-han, BAO Xi-cheng, LIU Xiao-kang, XING Yao-wen, GUI Xia-hui, CAO Yi-jun. Influence mechanism of fatty acid unsaturation on the intensification of low-rank coal flotation[J]. Chinese Journal of Engineering, 2023, 45(2): 195-205. doi: 10.13374/j.issn2095-9389.2021.10.26.001

Citation:

XU Meng-di, HE Lin, SI Wei-han, BAO Xi-cheng, LIU Xiao-kang, XING Yao-wen, GUI Xia-hui, CAO Yi-jun. Influence mechanism of fatty acid unsaturation on the intensification of low-rank coal flotation[J]. Chinese Journal of Engineering, 2023, 45(2): 195-205. doi: 10.13374/j.issn2095-9389.2021.10.26.001

Citation:

XU Meng-di, HE Lin, SI Wei-han, BAO Xi-cheng, LIU Xiao-kang, XING Yao-wen, GUI Xia-hui, CAO Yi-jun. Influence mechanism of fatty acid unsaturation on the intensification of low-rank coal flotation[J]. Chinese Journal of Engineering, 2023, 45(2): 195-205. doi: 10.13374/j.issn2095-9389.2021.10.26.001

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Influence mechanism of fatty acid unsaturation on the intensification of low-rank coal flotation

doi: 10.13374/j.issn2095-9389.2021.10.26.001

1.
Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, China
2.
School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China
3.
Institute of Resources and Materials, Zhengzhou University, Zhengzhou 450000, China

More Information

Corresponding author: XU Meng-di, E-mail: cumtxmd@outlook.com; XING Yao-wen, E-mail: cumtxyw@126.com
Received Date: 2021-10-26
Available Online: 2021-12-18
Publish Date: 2023-02-01

Abstract

Abstract

To study the effect of fatty acid unsaturation on low-rank coal flotation, oleic acid, linoleic acid, and linolenic acid with the same number of carbon atoms but an increasing number of double bonds were selected as flotation collectors and compared with conventional nonpolar collector diesel oil. Adhesion force measurements between particles and bubbles and molecular dynamics simulation of reagent adsorption were used to reveal the mechanism of unsaturated fatty acids enhancing low-rank coal flotation. The flotation results show that unsaturated fatty acid collectors surpass nonpolar diesel oil in flotation performance, and the flotation yield of low-rank coal increases with fatty acid unsaturation. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were used to analyze the surface morphology and surface functional groups of low-rank coal. SEM results show that the surface of low-rank coal is loose and contains many pores and cracks, which is not conducive to the spreading of chemicals on coal surfaces and the mineralization of bubbles and particles. The results of FTIR and XPS show that the surface of low-rank coal contains several oxygen-containing functional groups and has poor hydrophobicity, resulting in low flotation recovery. The adhesion force between bubbles and coal surfaces was measured in different collector solutions. The maximum adhesion between bubbles and coal surfaces increased with collector unsaturation in diesel oil, oleic acid, linoleic acid, and linolenic acid systems, indicating an increase in the floatability of coal particles with collector unsaturation. Furthermore, the molecular dynamics simulation of unsaturated fatty acid adsorption showed that unsaturated fatty acids spread on coal surfaces through hydrogen bonding between the polar groups of these molecules and surfaces. With an increasing number of double bonds, unsaturated fatty acids become more polar, and the spread of unsaturated fatty acids on coal surfaces gradually becomes more extensive, which leads to increasing particle floatability. This is the main reason for the increase in flotation recovery of low-rank coal with unsaturated fatty acids.
- low-rank coal flotation,
- fatty acid unsaturation,
- double bond,
- molecular dynamics simulation,
- maximum adhesion force

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