Study On Dust Migration Law And Dust Reduction Technology In Screening Workshop Of Coal Preparation Plant

Coal plays a vital role in China’s energy structure.As the level of mechanization in coal mines improves,the amount of dust created is gradually increasing.In the coal producing process,coal preparation is a critical phase.In the screening workshop of a coal preparation plant,dust pollution is getting increasingly severe,which not only wears down machine equipment and pollutes the work environment,but also has a negative influence on workers’ physical and mental health.As people pay more and more attention to their health,dust control is becoming particularly important.Most domestic and international researches on dust migration law and prevention and control technology is currently focused on fully mechanized coal mining face,but there are few researches on dust migration in coal preparation plant,and effective dust control measures are not taken,resulting in poor dust control effectiveness.As a result,this study focuses on dust migration law and dust control technology in the screening workshop of coal preparation plant.The dust migration law and dust concentration distribution characteristics in the screening workshop of a coal preparation plant were analyzed using a combination of theoretical analysis and numerical simulation.The vibrating screen,belt conveyor,and crusher created the greatest dust,according to a field measurement of the dust concentration in the screening workshop.Using the gas-solid two-phase flow theory,a geometric model of the screening workshop was built.Fluent software was utilized in the screening workshop to model and calculate the dust migration law under the impact of air movement.The results show that air flows into the screening workshop from the entrance,and that the air flow velocity decreases gradually as the migration distance increases,but the air flow converges at the air outlet,where the velocity increases sharply,and that the air flow velocity is the highest.The dust released by vibrating screen operation diffuses over a distance along the vibrating screen movement direction,then along the direction of air flow,until it encounters a wall block,at which point the direction of movement changes;the dust quality concentration on the vibrating screen surface is the highest,followed by the air outlet.The dust concentration gradually decreases as the distance from the vibrating screen increases.As a result,dust control measures should be implemented at the dust source.By reducing the amount of dust produced during the machine operation and taking dust control measures to reduce dust in the screening workshop,using numerical simulation method to study the dust control measures and using experimental method to study the influence of machine parameters on the amount of dust produced,reasonable setting of machine parameters.(1)The dust mass concentration of the breathing belt height in the screening workshop is compared using numerical simulation under varied velocity inlet,different size of airtight cover,and different wall surface conditions of airtight cover,and dust control measures are selected.Due to the air flow velocity being too big to easily produce secondary dust production,the dust concentration in the workshop decreases first and then increases with the gradual increase of the inlet air flow velocity.When the inlet air flow velocity is 0.8m/s,the dust concentration in the workplace is the lowest.Less dust escapes into the workshop as the size of the airtight cover grows larger,and the dust control effect is better under the trap wall condition than under the reflect wall condition.The dust control method combined with the airtight cover and spray is adopted.(2)For different parameters of the vibrating screen dust production capacity test,using an experimental approach.The results show that the dust production increases gradually with the increasing frequency of the vibrating screen,and the change of dust production is small when the frequency is 15～25 Hz.With the gradual increase of the vibrating screen amplitude of dust production gradually increased,the amplitude is greater than 2.5 mm dust production change is not obvious;With the increase of the coal action time in the vibrating screen dust production increases;With the increase of the coal mass in the vibrating screen,the dust production increases,so the operation parameters of the machine can be adjusted to reduce the dust production.After the dust control measures are applied in the field,the concentration of total dust and respirable dust meets the control standard,and the dust removal efficiency is more than 74%,which effectively reduces the dust concentration in the screening workshop.