Gravity Separation
Within the recycling industry, the
Separation Methods
used play a key roll in the successful recovery of materials.
Various approaches may be employed to take advantage of the natural force of
gravity
to effectively achieve density separation.
Sorting mixed wastes into a
Light Fraction
and a
Heavy Fraction
assists in the material handling for the mechanical separation into recyclable
commodities.
The common use of
air classification
or
floatation
systems are traditional methods of density separation.
In addition the use of a
centrifuge
is also very common.
Advancements in technologies have enhanced the use of
Vibrating Shaker Tables
and made possible development in
Heavy Medium Separation
Air Classification
The use of Air Classification or Pneumatic Separation Systems allows for the efficient capture of
Light Fraction
materials from mixed waste streams.
These materials may be sorted in individual commodities or typically become a component in Solid Recovered Fuel
(SRF).
The use of a Cyclone System is a more aggressive approach which is typically designed to handle specific materials.
Floatation
Floatation is typically described as a Float / Sink Gravity Separation method used to segregate materials
with different densities.
The separation of mixed feed stocks that contain such items as shredded materials like plastics and metals are well suited for
this type of segregation.
Flocculation may assist with the separation of fine particles that are suspended in liquids.
The floatation method is also ideal for the elimination of light contaminates for items classified as
Heavy Fraction
materials.
Centrifuge
A centrifuge uses the natural effect of rotational motion on mass and may be harnessed to separate different materials.
The use of a centrifuge device may speed up or amplify the separation process of sedimentation.
This effect is more properly referred to as a
Centripetal Force
Vibration Shaker Tables
Vibration Shaker Tables are an ideal method to separate mixed materials that have been segregated into a similar
particle size range but the property of the materials have a different density.
An example of this is sorting plastics from metals or different metals such as copper and aluminum from each other.
The vibration of a Shaker Table will cause the particles of materials to travel down an incline,
as the particles vibrate downward the diferent density material will walk apart
with the aid of a cross flow of air or water.
As the particles reach the end of the table they will have been separated into different streams
and will drop off the end table into separate collection destinations.
Dry Air Flow Separation
Dry Air Flow Separation across a Vibrating Shaker Table is an ideal method for separating materials
such as the output from a
wire chopping
operation.
The fairly uniform chop easily separates the copper, aluminum and plastic fractions.
Wet Water Flow Separation
The Wet Water Flow Separation system may be better suited to handle feed stocks that contain fine particle powders
since these materials create dust issues in an Air Flow Separation system.
Heavy Medium Separation
Heavy Medium Separation may be achieved with the traditional approach of density altered liquids or by using
free flowing solid particles.
Hot Sand Bath Agitation
The use of specific Hot Sand particles may be applied to preform a Heavy Medium Separation process.
The agitation of abrasive Hot Sand acts as a fluid bed stripping medium for the recovery of materials
from many types of complex items.
One example of a Heavy Medium Separation application is in the De-Soldering of scrap
Populated Circuit Boards.
Submerging Circuit board scrap into an agitating bath of hot sand (heated to the correct temperature)
may effectively remove and recovery the solder scrap.
Once the solder has been removed, the sand agitation is free to liberate the components from the circuit board substrait.
The liberated components and naked board substraits may be separated and removed from the sand bath and the sand is
regenerated and ready for another cycle.
Learn more about the industry with Recycling 101, You also may ask your Recycling Industry questions.
