Dimensional hydraulic classification

The unit operations implemented in separative techniques are most often preceded or coupled with classification phases into various batches of different particle sizes. In fact, gravimetric concentration equipment only performs well on materials with well-defined particle size ranges. Similarly, aggregate producers supply sands and gravels specifically defined by their particle size ranges. They therefore carry out preliminary washing which, among other things, eliminates fractions smaller than 60 or 100 µm.

This grading is very often carried out wet, and requires the use of screens or sieves for the grainiest fractions (greater than 1 or 2 mm). For fractions smaller than a millimeter, hydraulic size classifiers are used.

Hydraulic size classification refers to all processes used to separate solid particles from a suspension (or pulp) in a liquid medium into two or more fractions of different granularity by the sole action of an acceleration field (gravitational or centrifugal).