dry Stoner

Dry stoners are used to separate granular material according to the specific weight into two fractions and in dry material condition. They find their application mainly in the elimination of heavy impurities, such as stones, metallic particles. etc., from coffee, grain, pulse etc…


The granular material to be separated is taken to the table deck (in its conveying direction) through an adjustable spring-actuated flap. Depending on the grain size, the deck surface, with its adjustable inclination of 6-15°, is covered by a fine-meshed or a large-meshed wire cloth, through which is a steady and adjustable air flow is aspirated. The combined effect of the vibrating movement and
of the air passing through the deck causes an arranging in layers of the material flowing in (fluidisation).
The heavy admixtures sink towards the bottom and are moved to the highest point of the table deck surface (stone outlet) by the contact with the rough deck covering. The main product (cleaned product) floats towards the top and flows against the conveying direction of the table, to the lowest point of the deck surface, the cleaned product discharge. In the outlet area of the heavy particles, a „counter-air flow zone“ avoids the cleaned product being discharged into the heavy particles outlet during operation