Crushing plant

What is a crushing plant?

General Principle

A crushing plant is designed to reduce the size of rocks or recycled materials and obtain different particle sizes suitable for various uses (concrete, roads, etc.). The process generally includes several stages: primary, secondary, and tertiary crushing, followed by successive screenings to separate the materials according to their size.

Types of crushers and particle sizes obtained

Different types of crushers are used depending on the desired particle size:

• Jaw crusher: Produces intermediate-sized aggregates depending on the jaw spacing.
• Impact crusher: Allows finer particle sizes to be obtained, with adjustable settings by changing the plates.
• Gyratory crusher: Generally produces a single output particle size with a particle size distribution centered on an average diameter.

The choice of crusher and its settings depends on the input size of the material and the desired final particle size. For example, an impact crusher produces a greater reduction in grain size, thus producing finer materials than jaw or gyratory crushers for the same input diameter.

Screening and Classification

After each crushing stage, screening separates the materials into different particle size classes, typically:

• 0/4 mm: sand
• 4/10 mm: fine gravel
• 10/20 mm: medium gravel
• 20/40 mm: coarse gravel
• 40 mm: special-purpose stones

Screening can be repeated at several stages to refine the classification and meet the specifications of different markets.

 

Process Summary

• Initial size reduction through primary crushing.
• Secondary and tertiary crushing to obtain finer particle sizes.
• Screening after each stage to separate the granular fractions.
• Crusher and screen adjustments to adapt production to needs.

Comparison table of crushers by particle size produced

Crusher Type          Typical Setting / Modalities        Output Size (Examples)

Jaw                               Jaw Spacing                                      0/5 mm, 0/10 mm, 0/15 mm

Impact                        Plates (6, 20, 40 mm)                   Finer: 0/6 mm, 0/20 mm, 0/40 mm

Gyratory                     Single Setting                                   0/10 mm (centered on 5.5 mm)

A crushing plant therefore makes it possible to produce different granulometries by combining: the choice of crusher type, its settings, and successive screening stages, in order to precisely meet the needs of construction sites and industries.