Float Sink Tank

Float Sink Tank Rendering

Plastic Separation

General Description

Plastic separation from other material can be easily accomplished with the Float/Sink Tank. The float/sink concept relies on the specific gravities of the various materials processed in the tank relative to the specific gravity of the base solution in the tank. Those materials with a specific gravity higher than that of the base solution will sink while those with a lower specific gravity will float. The specific gravity of the base solution can be changed as necessary though the addition of the various chemical additives.

In the Polymer Recovery Systems Float/Sink Tank, material is deposited on to the surface of the water in the tank. Heavy material sinks to the sloped bottom of the tank. An auger or drag conveyor, which continually sweeps the bottom surface conveys this material to an above-water discharge. Buoyant material is conveyed to the opposite end of the tank where it is discharged by a partially submerged screw conveyor or a rotating paddle.

Float Sink Tank


  • Heavy duty electric drive motors are mounted high and safely out of the way
  • All motors are variable speed to allow precise control of material flow
  • Tank water level is regulated by a simple manual float valve
  • All components that contact the water and process material are 304 stainless steel or plastic
  • Tank is constructed of stainless steel with a steel understructure and frame
  • Made to complement the Polymer Recovery Systems Air Classification System for added plastic separation effectiveness


The float sink tank can process at rates of up to 2,000 pounds per hour depending on bulk density of the material.


The process material is propelled in a gentle Z-shaped flow pattern on the surface of the water solution traveling approximately 25 ft. This allows longer material residence times and superior separation in a compact unit. The flowing material is gently submerged and propelled by a series of auger flight segments and paddles to completely wet and de-aerate the plastic flake.

The separated float and sink components are discharged at a common end location so either component can be easily routed to a washer/dryer or other post process plastics machinery.

Optional Equipment

  • Discharge water collection/recirculation tanks
  • Discharge water screening/filtration systems
  • Water spray bars for light to moderate cleaning ability
  • Post-separation dryers (centrifugal or rotary)
  • Pre-separation air classification

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