New Insight into Temperature Effects on Low-Rank Coal Flotation Using Diesel as a Collector

Xicheng Bao; Junling Liu; Shasha Wang; Dongqin Chen; Wenjin Xu; Deke Zhang; Jihui Li; Yaowen Xing; Mengdi Xu

doi:10.1021/acsomega.3c00774

New Insight into Temperature Effects on Low-Rank Coal Flotation Using Diesel as a Collector

ACS Omega. 2023 Apr 23;8(17):15479-15487. doi: 10.1021/acsomega.3c00774. eCollection 2023 May 2.

Authors

Xicheng Bao^{1

2}, Junling Liu³, Shasha Wang^{1

2}, Dongqin Chen^{1

2}, Wenjin Xu^{1

2}, Deke Zhang^{1

2}, Jihui Li⁴, Yaowen Xing¹, Mengdi Xu¹

Affiliations

¹ Chinese National Engineering Research Center of Coal Preparation and Purification, Xuzhou, Jiangsu 221116, China.
² School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
³ Henan Energy Group Co., Ltd. Zhengzhou, Henan 450046, China.
⁴ School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China.

Abstract

Efficient flotation of low-rank coal is of great significance for the development of green and low-carbon cycles. Temperature is a crucial parameter of flotation, but the mechanism of its effect on flotation lacks understanding. In this paper, the mechanism was studied by kinetic flotation, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, low-temperature liquid-nitrogen adsorption (LP-N₂A), X-ray photoelectron spectroscopy (XPS), and molecular dynamics simulation. The flotation combustible recovery gradually decreases as temperature rises. Compared with 60 °C, the combustible recovery at 5 °C increases by 18.13%. The desorption energy for oil droplets decreases as the temperature rises. As a result, the oil droplets are easier to desorb at high temperatures. The SEM and LP-N₂A results demonstrate that the pores and fractures of the coal sample are well developed. Also, the oil-water interfacial tension and viscosity of oil droplets decrease as the temperature rises, while the diffusion ability increases. These increase the volume of oil droplets that penetrate into the pores, resulting in poor spreadability of oil droplets on the coal surface. The average volume of bubbles gradually increases as temperature rises, which renders the flotation foam unstable and worsens the flotation. Therefore, the flotation performance is better at low temperatures.