A study of the effects on temporal and spatial distribution of particle groups and sizing effect produced by productivity in variable-amplitude equal bed-thickness screening process

Numerical simulation is made of the operating process of the variable-amplitude equal-bed-thickness screen using descrete element method (DEM) to explore the law governing the spatiotemporal distribution of particle groups under the conditions that the screen operates with varying productivities.Whereas, the law of the distribution of the particle groups passing through various sections of the screen at different productivity of the screen is investigated through model screening test.Simulation test shows that:the mass of fine particles in undersize product tend to become increased with time; at an exciting frequency of 16 Hz, a mean amplitude of 2.75 mm and a screening time of 3.0 s, the material bed on sieve tends to become equal in thickness; and at a screening time of 8.97 s, the separation process of the coarser and finer sizes is basically finished.When the screen operates with a unit capacity of 14.73 t/m²·h, the screening efficiency and the total of misplaced materials are found to be 83.56% and 17.21% respectively through simulation test, and 85.24% and 16.42% respectively through screening test.With the increase of the screen's productivity, the particles tend to basically undergo loosening and stratifying process at the screen's 2nd section.At the 3rd section, as the bulk bed material passes the screen, a best screening effect can be expected, and at the 1st section (feed end) and the 4th section (discharge end) the screening effect is relatively poor because of the presence of the phenomenon of heaping up of materials.