Analysis of sieve holes blocking in a vibrating screen and a rotary and drum screen

Main objective of screening is to separate a group of grains, which dimensions fall within the specified limits, from the given feed. A large number of sieve and screening machines designs is available. During screening of granular materials in industry, sieve holes are often blocked. The phenomenon of screen blocking involves grains of varying sizes and geometries being clogged in sieve holes. This significantly decreases the screening efficiency. The mechanism of sieve holes blocking is largely random. A dry and contamination-free granular material with 0.1-2.5 mm size was screened in this study. The grains with spherical (agalite and chromium stainless shot), sharp-edged (aggregate) and irregular (quartz sand) were used in screen tests under various conditions. Screening tests included both intermittent, as well as continuous screening. Identification on blocking of sieve holes was conducted using vibrating devices and a rotary and drum screen with a cone-shaped sieve. This paper specifies the main operational parameters of these machines that had remarkable influence on the blocking of sieve holes.