Influence Of Particle Size Distribution On Dust Production In A Free Falling Process Of Bulk Material

During industrial production process,bulk material transportation is an important source of dust generation.It is very important to figure out the mechanism of dust generation thus the dust could be controlled to ensure production safety and personnel health.In order to figure out the influence of particle size to dust generation,five group of SiO2 in factory is used.The median diameter is 82.5?m,145.8?m,209.5?m,245.1?m,314.5?m successively.This paper explores the dust diffusion and its influencing factors during free-falling process.The particle size distribution of bulk material has a significant effect on dust emission in a free falling process.Considering size distribution as an important variable,the dust emission discipline during free-falling influenced by drop height,outlet diameter,particle size distribution is discussed.Besides,dust was divided into two parts using rigid surface and water surface: the first fugitive dust caused by escaping during free falling and the second fugitive dust caused by collision.Based on fugitive dust rate which illustrated the quantity of dust production,the particle-size fugitive dust rate is introduced to describe a certain particle size range's dust forming proportion.The effect of drop height,outlet diameter and size distribution to fugitive dust rate and particle-size fugitive dust rate is investigated while particle size ranges 0-10?m.As the damage extent to people changes when the particle size varies,the 0-10?m particles were divided into eight ranges,and six ranges were mainly analyzed.The influence of drop height,outlet diameter and particle size distribution in different particle size range is obtained.Thus provides an effective theoretical basis to reduce ventilation system's energy consumption and improve dust removal system'sefficiency.The results show that both the fugitive dust rate and particle-size fugitive dust rate increase when median diameter and drop height increase and outlet diameter decreases when particle size ranges 0-10?m.Compared with the second particle-size fugitive dust rate and general particle-size fugitive dust rate,the first particle-size fugitive dust rate is affected least by each factor.Among the three factors,the drop height has the greatest effect on the first particle-size fugitive dust rate.The influence of drop height and median diameter on the second particle-size fugitive dust rate is equivalent.Comparing the particle-size fugitive dust rate of different particle size range,It is discovered that the median diameter has a great influence on particle-size fugitive dust rate whose size ranges 1.1-2.1?m,the drop height influences particle-size fugitive dust rate whose size ranges 3-4.7?m most,while the outlet diameter has the biggest influence on particle-size fugitive dust rate whose size ranges 5.8-9.0?m.The influence of particle size,drop height and outlet diameter to dust generation during free falling is analyzed,the fugitive dust rate and particle-size fugitive dust rate is studied when three factors varies.The conclusion is a theoretical basis to dust control.