On Tue, 22 Sep 2009 16:59:19 -0700 (PDT), Art Unwin
wrote:

On Sep 22, 5:30*pm, Registered User wrote:
On Tue, 22 Sep 2009 13:24:17 -0700 (PDT), Art Unwin

wrote:

Well look at how salvage yards sort out metals into different
enclosures.
They apply a displacement current *to a conveyor where each piece of
metal is elevated with spin such that it lands in the appropriate
enclosure which is dependent on the resistivity of the metal elevated.

This isn't exactly how such systems work. Abstractly the system is a
metal detector and a sorting table hanging off a CAN. A controller at
the other end of the CAN 'reads' the discriminator and 'writes' to the
sorter. The writes open and close ejector nozzles. These are the magic
devices that cause the material to 'elevate with spin'.

This method of elevating scrap for recovery has been used for years
and it is the same action that is applied to particles for radiation.
Why would you need a citation for a practice that is well known and in
use?

Because you might be wishing your agenda into how you propose things
work. Who'da thunk that!

Interesting. Can you point to an article or something on the web that
describes what you
say. For myself I have only run into articles by special purpose
machine manufacturers
who deal with sorting machines for scrap yards which deals with many
materials including plastics , glass etc as well as different metallic
materials. This sorting aproach that you mention sounds rather
interesting if they are relying on magic or voodoo!

There is no magic or voodoo involved with a controller area network.

There are all manners of industrial separators and practically all are
custom purposed for the user and the particular type of refuse
stream(s) they will be dealing with. It's certainly not a
one-size-fits-all industry. Most use a combination of methodologies.
Magnetic eddy currents are one means and their use in the industry
only goes back a couple of decades.

In a nutshell here is how eddy currents are primarily used in
materials sorting.

As the eddy current roller spins it creates alternating polar fields.
When inert (non-metallic) material enters a field a field of the same
charge is generated around the object. As the roller spins the next
field is of opposite charge to the field of the object and the object
is repulsed. The momentum provided by the conveyor belt added to the
repulsive force changes the trajectory of the object as it leaves the
end of the conveyor belt. As a consequence inert objects travel
further off the end of the belt.

Non-ferrous metals do not benefit from a charged field and fall
straight down due to good old gravity. Ferrous metals are attracted to
the roller and remain on the conveyor belt until they move past the
roller on the underside of the table. Then those materials also fall
straight down but at a different location from the non-ferrous metals.

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