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The HDS-V (hydraulic density separator with vibrating screen) was designed to provide a more effective method of separating light and heavy solids than a simple water bath.


Conventional static water baths have been used for a long time to separate particles with a density greater than that of water (i.e. stones, concrete, etc.) from those less density than water (i.e. wood, plastic etc.). However these  do not work very well on waste streams containing heavy plastics (such as pvc which has a particle density of 1.4 to 1.5t/m2) and saturated wood.


To overcome this limitation we developed the HDS unit which uses an upwards flow of water to help separate the heavy plastics, etc. from the aggregate.  Essentially those particles that settle faster than the upflowing current sink to the bottom of the unit whilst those particles that settle slower than the upflowing current  float. 


The Process

  • Feed material, (generally 75mm down), are fed into the unit via a feed hopper.

  • The heavy particles are removed from the bottom of the unit by the inclined auger, whilst the light particles are carried away by the water onto a dewatering screen. 


  • The water passes through the screen and is recirculated back into the separation chamber where the light fraction is lifted over the wier, dewatered and discharged off the end of the screen.


  • An impeller is used to create the upflow and by varying its speed, the separation point can be controlled to suit the material being separated and to favour the product of greater value.


  • In addition it is possible to change the decks in the vibrating screen depending on the particle size of the light fraction.


  • In addition to glass, we have successfully used the separator to destone compost oversize, clean up trommel fines from construction demolition waste and it is also integrated into our WT-250 Gritbuster plant to dewater oversize road sweeper waste.


  • Depending on the amount of fines present in the feed it may be necessary to add a water treatment stage to the process to prevent a build up of suspended solids turning the water into a thick slurry.

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