Spirals AKA-SPIN are sorting devices which separate materials according to their density differences. They can be used for a grain size range from 60μm up to 2mm, with a throughput per spiral ranging between 1– 4t/h. If a higher throughput is required, 2 or 3 spirals can be combined to form one column.

Principle of Operation

The slurry (10% – 40% solids depending on application) is fed into the spiral from the top. Spread on the spiral surface, it moves down by gravity. A transverse flow is superimposed to the main flow downwards. This combination results in a separation of the particles contained in the suspension, depending on their density. Particles with a lower specific gravity, such as wood, coal or organic matter, are concentrated in the outer areas of the flow. Particles with a higher specific gravity are directed towards the spiral axis.

Design Features and Advantages

  • Separation of up to 3 fractions: heavy, middling and light density products
  • Wear resistant polyurethane coating of the spiral body
  • Light weight and robust design
  • Spirals can be designed into columns and banks


  • Ore and mineral sorting
  • Coal processing
  • Sand cleaning
  • Soil remediation
  • Municipal residues