Study On Dust Diffusion Law Of Lithium Battery Cathode Materials In Workplace

With the mass production and wide use of lithium ion batteries,its cathode material demand is progressively increasing,and large quantities of dust are resulted during the process of production.Compared with traditional materials dust,lithium dust has bigger density,smaller particle size and toxicity.The study on the physical properties,production,suspension,drift mechanism,effective collection and catch measures of the lithium dust has become a key and urgent scientific problem,which has important scientific significance and practical value.Therefore,in accordance with the study result,through a field experiment in a lithium battery cathode material production workshop,the physicochemical properties on dust's mechanical characteristics,morphology,distribution,particle size,infiltration velocity,etc are explored.The wind velocity,dust concentration distribution and motion trajectory of each working procedure is carried out by using FLUENT3 D software.Finally,according to the results of the research on the lithium battery cathode materials in the workplace,the dust control improvement program is further proposed.The main contents and conclusions are as follows:(1)The dust in the workplace of lithium battery cathode materials from a diffusion angle is analysied by utilizing the aerodynamics theory,so as to reveal the dust production mechanism and the diffusion rule.The results show that the lithium dust in the workshops mainly comes from three aspects: Firstly,the big drop between feeding and discharge heads of different working procedures,where the seal is not good,resulting in dust emission;secondly,during the process of material transfer,the smaller particles of the materials dissipate under the action of airflow;thirdly,the dust comes from the operation of workshop equipment.On the basis of this,the diffusivity equation of transient point source of dust and the control equation of continuous point source are obtained in the condition of static,laminar and turbulent flow.(2)Using scanning electron microscopy test method,the physicochemical properties of the dust in each process workshop are obtained,showing the workshop dust mainly contains spherical and lumpy dust,and the spherical dust takes a bigger proportion.The actual density of dust is largerthan the bulk density;the infiltration velocity andthe average particle size of dustfrom the sintering workshop up to vanishing magnetism and packaging workshop presents an increase-and-decrease tendency.dust,the gradient rule of dust settlement and sedimentation is obtained and the sedimentation effect of particle size,airflow,particle shape is explored.The results show that the dust concentration in mixing workshop and sintering workshop is small,where the total dust concentration and respirable dust concentration were below the concentration of safe production,however the concentration of respirable dust accounted for a higher proportion;the dust concentration in crushing workshop,screen workshop and magnetism vanishing and packaging workshop is all higher than the allowed maximum density,respiratory dust decreases with the increment of diffusion distance.(4)Using FLUENT 3D software and k-e mode,the diffusion process of dust is simulated.The results indicated that the the larger values of wind speed for each process workshop all appeared around the dust source and air outlet,and there was no vortex phenomenon.The dust initially distributed nearby the dust source and diffused with the air current.The dust concentration in each workshop decreased with the increase of diffusion distance on the whole,which coincides with the experiment results.(5)The general situation of dedustingsystem,dust sources and existing problems of each workshop were analyzed in accordance with the actual situation of lithium battery cathode materials' workplace and based on which optimize dust prevention,perfect the existing dust-removal system in each process workshop and put forward treatment measures for handling the dust in workplace.It has a certain practical guiding significance in governing and managing dust in workplace,and provides the dust research and control of batteries' cathode materials' workplace with the theoretical foundation.