A novel flotation technique combining carrier flotation and cavitation bubbles to enhance separation efficiency of ultra-fine particles

Shaoqi Zhou; Xuexia Wang; Xiangning Bu; Mengdie Wang; Bairui An; Huaizhi Shao; Chao Ni; Yaoli Peng; Guangyuan Xie

doi:10.1016/j.ultsonch.2020.105005

A novel flotation technique combining carrier flotation and cavitation bubbles to enhance separation efficiency of ultra-fine particles

Ultrason Sonochem. 2020 Jun:64:105005. doi: 10.1016/j.ultsonch.2020.105005. Epub 2020 Feb 6.

Authors

Shaoqi Zhou¹, Xuexia Wang¹, Xiangning Bu², Mengdie Wang¹, Bairui An¹, Huaizhi Shao¹, Chao Ni¹, Yaoli Peng¹, Guangyuan Xie¹

Affiliations

¹ Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China.
² Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China. Electronic address: xiangning.bu@foxmail.com.

PMID: 32062426
DOI: 10.1016/j.ultsonch.2020.105005

Abstract

In this paper, a novel flotation technique that combines nano-scale bubbles generated by hydrodynamic cavitation (HC) and carrier flotation is proposed to promote the flotation efficiency of a high-ash (43%) ultra-fine coal sample (<45 µm). We investigated the mechanism by which cavitation bubbles enhance the separation efficiency of carrier flotation using focused beam reflectance measurements, polarizing microscopy, and extended Derjaguin-Landau-Verwey-Overbeek theory. The carrier particles (polystyrene (PS)) and fine coal were pre-treated in a venturi tube and then floated in a laboratory mechanical flotation cell. The flotation results indicate that the presence of cavitation bubbles significantly improved the carrier flotation performance of high-ash ultra-fine coal. This improvement was attributed to the presence of highly hydrophobic PS, which creates additional gas nuclei in the flotation system. The nano-bubbles, which were produced by the venturi tube and adhered to the fine coal particle surfaces, were conducive to the agglomeration of fine coal particles into large aggregates. Moreover, the nano-bubbles functioned as "bridges" of interaction between the carrier particles and large aggregates of fine coal particles. This paper mainly focused on the effect of carrier (PS) and HC on high-ash fine coal. The influence of different HC intensities on carrier (PS) flotation was discussed. Two models for the interactions between the coal particles, nano-bubbles, and PS during cavitation were proposed and were proved using the E-DLVO theory.

Keywords: Aggregate; Carrier flotation; Hydrodynamic cavitation; Nano-bubble; Ultra-fine particle.