MRO Magazine

Density separation tanks

By MRO Staff   

Environment & Sustainability Health & Safety Resource Sector Density separation tanks

Photo: Herbold

Herbold Density Separation Tanks or Sink-Swim Tanks use water to separate plastics of different densities in post-consumer recycling systems. Can be used to separate contaminants from homogenous plastics. Items are introduced to the large steel tanks by a feeding screw or conveyor at one end.

Three or four transport drums move the material from one end of the tank to the other. During this process higher density plastics sink to the bottom of the tank, while lower density plastics float on the surface of the water.

Lighter plastics exit the tank via a top discharge and heavier items are continuously removed by a scraping chain conveyor mounted below the bottom of the tank.

Tanks are available in three sizes from 78” by 31” up to 157” by 71” with drive motors from 1.5 to 15 hp. Throughputs vary depending on material and tank size.




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