Dense medium separation plant
Dense medium separation machine
Dense medium separation recycling machine

Dense medium separation

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Ad Rem owns the rights on a patented unique bi-directional dense medium barrel that proved to be the most accurate dense medium separator ever employed in the separation of a variety of materials ranging from vegetables to plastics and non-ferrous metals.

The Ad Rem technology is based on 4 points:

  1. Correct injection
    At the critical moment of introducing solids into the drum, the floats of the typical DM drum are easily buried with sinks and cannot find their way to the surface of the bath. However in the Ad Rem bi-directional design, the medium together with solids is injected over a large separation zone, making it almost impossible to bury floats with sinks.
  2. The stability of the medium
    A typical dense medium bath is relatively deep, and this makes it difficult for the suspension particles to remain in suspension. If a medium is not stable, we find water at the top of the bath and a dense sludge at the bottom of the bath, and of course, in this stratified liquid, no separation takes place. Instead of a deep bath, Ad Rem chose a shallow bath, and the gentle action of the sinks scrolls pulling underneath the bath provides just the right amount of agitation to keep the suspension medium stable.
  3. Correct floats dynamics
    The typical dense medium drum is quite short (only 1.0 – 1.5m in length), and it happens quite often that before a particle can float or sink, it is already out of the bath. Therefore, in the Ad Rem design the length of the separation zone is greatly extended, increasing the residence time of a particle in the bath, therefore making it impossible to find sinks in floats.
  4. Correct sinks dynamics
    In the conventional dense medium drum, the curtains needed to prevent floats from crossing over with sinks are located in the separation zone and, due to turbulent fluid movement in the vicinity of these curtains, floats are easily sucked under these curtains and report with sinks.

In the new Ad Rem design, however, the curtain that prevents floats from crossing over with sinks is situated completely outside the separation zone, making it impossible to find floats in sinks. In the classical design, sinks are continually lifted out of the bath by means of a series of lifters welded to the wall of the drum, and at each rotation of the drum, these sinks are removed from the bath while still in the separation zone. The action of these sinks evacuation lifters, passing underneath the two curtains running the full length of the separation zone, creates a great deal of turbulence, and this turbulence completely destroys the accuracy of separation. This severely limits the speed of rotation of the drum as well as the tonnage of sinks evacuated within a given period of time. Consequently the typical DM drum cannot handle a large quantity of sinks.

However in the Ad Rem design, sinks are lifted up and out of the bath only when they are completely outside of the separation zone. Scrolls welded to the bottom of the bi-directional drum gently move the sinks in one direction, while the floats flow out on the surface of the bath in the opposite direction. When the sinks exit the separation zone, they drop down underneath a curtain into an expanded drum and only at this point they are screwed up and out of the bath. Since there are no lifters and curtains within the separation zone, a bi-directional drum can be rotated at relatively high speeds without jeopardizing the accuracy of separation. Since there are no lifters and curtains within the separation zone, the entire surface of the bath is available for separation and remains fully visible to the operator at all times.

Dense medium separation system
Dense medium separation machine
Dense medium separation plant

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