Mechanical screening

Mechanical screening separates particles by size by passing material over or through a screen with openings of selected dimensions. It is widely used to classify bulk solids and remove unwanted size fractions.

Screen aperture: An opening in a screening surface through which particles smaller than its effective dimensions may pass. Aperture dimensions set the nominal size boundary between undersize and oversize material.
Particle-size distribution: A description of the relative amounts of particles across different size ranges in a material. Screening divides this distribution into size fractions.
Mining: The extraction of valuable geological materials from the Earth. Screens classify crushed ore and control particle sizes between processing stages.
Air classification: A process that separates particles using differences in their aerodynamic behavior in a moving gas. Unlike screening, it separates by motion in air rather than passage through apertures.
Screening efficiency: A measure of how effectively a screening operation separates particles into intended size fractions. It captures how well particles are routed to the correct product streams.
Sieve analysis: A method for determining particle-size distribution by passing a sample through a series of sieves. It measures the size fractions produced by screening.
Aggregate (geology): Granular material such as sand, gravel, or crushed stone used in construction. Aggregate plants screen material into graded products for construction.
Hydrocyclone: A device that separates particles or droplets from a fluid using a swirling flow and centrifugal effects. It classifies suspended solids in liquid rather than dry material on a screen.
Vibrating screen: A screening machine that vibrates a perforated surface to stratify and separate particles by size. Vibration promotes particle movement and passage through the openings.
Mesh (scale): A measure of sieve or screen fineness based on the number of openings per linear inch. Mesh notation commonly describes screen fineness, though aperture dimensions are more direct.

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