The filter element, made of imported PTFE millipore medium coated, is high in fineness and in compliance with national standards on indoor emission. This type is featured as large in filter area and air volume, small in floor space, long in service life, low in noise level and sound in the effect of dust collection. Particles in dust/soot are driven by the suction hood into the filter unit, where fine ones are effectively prevented by the filter cartridge from permeating into the filter (efficiency up to 99.9%). The suction hose is made of superior composite materials resistant to high temperature and wear, thus long in service life. Applicable to purification of flue gas and dust in welding and grinding fields and recovery of rare metals and other valuable materials;