Mechanistic study of the effect of air bubbles on the press pressure and dewatering performance of flotation concentrate coal

YANG Zhanghua; DONG Xianshu; CHEN Ruxia; FAN Yuping; MA Xiaomin; FENG Zeyu

doi:10.13226/j.issn.1006-6772.23031402

Abstract：The addition of frothing agent makes the coal slurry flotation process produce stable,large viscosity value and difficult to break bubbles,and the accumulation of large amount of bubbles seriously restricts the pressurization and dewatering effect of flotation concentrate coal.In order to investigate the influence mechanism of bubbles on the filtering pressure and dewatering performance of flota-tion concentrate,the influence law of bubbles on the filtering pressure,cake displacement,filtrate quality and cake moisture of flota-tion concentrate using a new pressurized dewatering device was investigated,the dewatering mechanism by a series of methods such as Im-ageJ image processing,rheological characteristics test,FBRM test and SEM characterization was explored.The results show that the pres-sure required to press filter the flotation concentrate increase from 451.2 kg to 540.7 kg at an aeration rate of 0.3 m3/h,and the filter cake moisture increas by 10.7 percentage points.ImageJ image processing shows that the distribution proportion of small diameter bubbles increases with the increase of air volume,rheological test shows that with the increase of air volume,and the viscosity of flotation cleaned coal increases and the dynamic shear τ0 increases from 0.994 7 mPa to 1.170 3 mPa,indicating that the directional rear-rangement of particles is enhanced.The FBRM test show that the presence of air bubbles increase the particle size of flotation concentrate,coalescence occurred,and the interaction force between particles increase.SEM results show that air bubbles make the flota-tion concentrate particles agglomerate.The presence of air bubbles make the flotation concentrate particles more closely arranged,the in-ter-particle capillary radius decrease,the pressure required for filtration increase,and the pore space of the filter cake become smaller,the water migration path is more complicated,which is not conducive to the removal of water.