Gravitational inertial air classifiers.

Gravitational inertial air classifiers

A dry solution for the precise separation of ultrafines in manufactured sand production

Gravitational inertial air classifiers separate fines from crushed rock in manufactured sand production. The dry solution uses a unique chamber and airflow design to ensure precise separation of ultrafines from sand with an accuracy of microns.

Ideal for classifying manufactured sand

Optimal gradation and particle moisture

High accuracy separation from 300 μm to 63 μm 

Tailored by Metso to meet your needs 

The most efficient way to achieve ultrafine separation

Gravitational inertial air classifiers reduce the volume of ultrafines in manufactured sand, which helps to meet strict specifications and improve end-product quality.

The solution uses a unique chamber and airflow design with ceramic liners to ensure precise separation of ultrafines from sand. The end result is sand with optimized shaping, gradation, and particle moisture.

Separating different fractions in with accuracy

Gravitational inertial air classifiers use a primary and a recirculating secondary airflow to separate fines from coarse particles.

Because the airflows are not affected by wear, the grading remains consistent to an accuracy of microns. At the same time, particle moisture remains at an optimal level.

Different fractions ranging from 300 μm to 63 μm can be separated with an accuracy of microns.

Thanks to the process not using water, it is both economical and environmentally friendly as well as ideal for colder climate.

Easy to adjust

The volume of ultrafines in the end product is adjusted by changing the total airflow, and by changing the ratio of primary and secondary airflows.

With the right combination both separation size and accuracy can be fine-tuned to meet application requirements.




Unique ceramic liners
Ceramic liners that last for years

Highly durable ceramic tiles are used to protect the classifier’s body.

The tiles need to be replaced every four to seven years, which is double the two to three year replacement interval of hard-rock liners.

Ceramic tiles are suitable for all types of feed material: abrasive, hard, and soft rock.

A complete solution

For precise dry classification of different fractions of sand, a complete solution for separation and dust collection is needed. The system consists of an air classifier and dust-collection system with a fan, a compressor, airlock, and piping.

Metso can provide a complete system with all equipment and steel structures, or individual equipment as needed. Each system is designed according to customer need and the requirements of local safety and environmental regulations.

How it works?
  1. Feed material is evenly introduced from the top of the classifier in a controlled curtain along with primary air
  2. Secondary air is drawn in at the bottom, inducing a scrubbing effect on similar-sized particles
  3. Recirculation and scrubbing enables high efficiency and precise separation of ultrafines
  4. Coarse particles drop out of the bottom of the classifier through an airlock

Gravitational inertial air classifiers technical specifications

Gravitational inertial air classifier brochure
Manufactured sand production
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