超声波强化低阶煤浮选研究现状及展望

低阶煤表面孔隙发达、含氧官能团含量高, 导致常规浮选效果不理想。超声波作为一种常用的煤泥浮选强化手段, 已开展了较多相关研究工作。首先介绍了超声波空化理论(空化阈值、瞬态和稳态空化)和声辐射力(初级和次级); 然后, 从颗粒破碎、表面清洗和物性改变、药剂乳化和分散、微纳米泡效应、浮选气泡大小和泡沫层的变化4个方面对超声波强化低阶煤浮选的研究现状进行了梳理; 最后, 对超声波强化低阶煤浮选研究的发展方向进行了展望, 建议从稳态空化强化低阶煤表面疏水性、声辐射力促进低阶煤颗粒-气泡气絮体的形成、瞬态空化效应强化浮选药剂的捕收性能、声辐射力强化气泡兼并抑制脉石夹带四个方面进一步研究超声波强化低阶煤浮选的机理。

Ultrasound-Assisted Flotation of Low-Rank Coal: A Review of the Current Status

Low-rank coal has developed surface pores and high content of oxygen-containing functional groups, resulting in unsatisfactory conventional flotation results. Numerous studies demonstrated that ultrasound is a commonly used enhancement method for coal flotation. This article first introduces the theory of ultrasonic cavitation (cavitation threshold, transient and steady-state cavitation) and acoustic radiation force (primary and secondary). Then, the research status of ultrasound-assisted flotation of low-rank coal is reviewed from 4 aspects: particle breakage, removal of the surface coating, modification of surface properties, emulsification and dispersion of flotation collectors, micro-nano-bubble effect, and the changes of flotation bubble size and foam layer changes. Finally, the development direction of the research on ultrasonic-enhanced low-rank coal flotation is prospected. It is suggested that the mechanism of ultrasound-assisted flotation of low-rank coal should be further studied from four aspects: the enhancement of steady-state cavitation on the surface hydrophobicity of low-rank coal, the formation of flocs between low-rank coal particle and cavitation bubbles induced by acoustic radiation force, the enhancement of transient cavitation on the collection performance of flotation reagents, the enhancement of bubble coalescence and the inhabit of gangue entrainment induced by acoustic radiation force.