Spirals AKA-SPIN are sorting devices which separate the materials according to their different densities. They can be used for a grain size range from 60 μm up to 2 mm, with a throughput range per spiral of 1– 4 t/h. If a higher throughput is required, 2 or 3 spirals can be combined to form one column. Several spiral columns can be joined to form banks of 2, 4, 6 or 8 columns, with one distributor for the inlets and collector chutes for the outlets.

Principle of operation

The slurry (content 10 – 40% solids depending on application) is fed into the spiral from the top. Spread on the spiral bottom, it moves down by gravity. A transverse flow directed inwards on the sluice bottom or outside on the slurry surface, 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 PU coating of the spiral body
  • Light weight and robust design
  • Spirals can be designed to columns or banks

Example drawing


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

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