It has election and purification functions. 1. The dust filtration is designed for Expressway joint gravel screening units with large flow, high concentration (Dust Volume is more than 1000g/m) and irregular dust emission characteristics of working conditions; 2.It meets the requirements of Two and Three class areas under GB16297-1996; 3.The filter has the advantages of high efficiency dust removal, small amount of maintenances, long service life, elegant appearance, etc; 4.It has election and purification functions;