Note: Descriptions are shown in the official language in which they were submitted.
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PATENT APPLICATION
TITLE
METHOD FOR SEPARATING FRANGIBLE MATERIAL FROM
MALLEABLE MATERIAL
FIEI n OF THE INVENTION
The present invention relates to recycling apparatus and methods
in general, and to apparatus and methods for separating frangible
materials from malleable materials in particular.
- BACKGROUND OF THE INVENTION
With decreasing capabilities in existing landfills, the unavailability
of additional landfill sites, the increasing costs of landfill operation and
the enactment of environmental laws making recycling desirable and
even mandatory, many waste management companies and municipalities
have installed waste processing systems which separate the components
of waste for subsequent processing such as recycling. Currently, waste
management companies and municipalities sort the waste into recyclable
and non-recyclable goods. Because of these waste disposal problems,
there are added pressures on municipalities and waste management
companies to recycle all possible materials that they can.
Efficient resource recovery depends upon separating the maximum
amount of desirable material from the refuse using relatively few
separating components. Certain commonly recyclable materials, such as
glass, have been u,nrecoverable from products which closely associate
non-ferrous metals, such as lead, with the glass. Because lead under
certain conditions may be treated as a hazardous waste, it is particularly
desireable to reduce the overall weight and volume of disposed waste
which contains any amount of lead.
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It was common in early waste processing systems to merely shred
the waste in hammer mills or other comminuting devices. The refuse
- was shredded or pulverized making it virtually useless for recycling. It isdesirable to minimize the degree of shredding which occurs prior to
separation. Therefore it is desirable to provide a method in which items
made of different materials can be processed to separate out the
non-recyclable materials from the recyclable materials. These include
items made of frangible and malleable materials that are the subject of
the present invention.
What is needed is an apparatus for separating frangible materials
such as glass and certain plastics from metal.
SUMMARY OF THE INVENTION
The apparatus and method of this invention effectively and
efficiently separate a frangible material, such as glass of a light bulb,
from malleable materials such as lead The method of the present
invention accomplishes this by crushing the frangible material into small
fine particles and flattening and elongating the malleable material into
larger particles. The small frangible particles can then be separated from
the larger malleable particles on the basis of size by a screening device in
preparation for recycling.
Frangible material such as glass is more brittle than malleable
material such as lead or other metals, and the crushing process which
compresses and fle,xes the material as it passes through the nip of
opposed rollers breaks the glass, reducing it to fines, which pass through
the screen. On the other hand, the malleable material is merely flattened
and elongated making it unable to pass through the screen.
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It is a feature of the present invention to provide a method in
which objects made of both frangible and malleable materials may be
recycled by separating the frangible material from the malleable material.
It is another feature of the present invention to provide a method
for crushing and compressing waste containing frangible and malleable
materials to produce a size differential in the different materials so that
the materials may be effectively distinguished and separated on the
basis of size in preparation for recycling.
It is a further feature of the present invention to provide a
screening device which is highly efficient in separating small frangible
particles such as crushed glass from larger malleable particles such as
compressed metal and which experiences minimal blinding, or clogging,
even under undesirable operating conditions.
Further objects, features, and advantages of the invention will be
apparent from the following detailed description when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
The drawing is a simplified schematic view illustrating the method
of this invention for separating frangible materials such as glass of light
bulbs from malleable materials such as the lead ends of light bulbs.
DESCR!PTION OF THE PREFERRED EMBODIMENT
Referring more particularly to the drawing, wherein like numbers
refer to similar parts, a waste separation assembly 20 for separating
frangible material from malleable material in a recycling process is
shown. The assembly employs a conveyor 22 or other distributing
device to feed a steady flow of mixed waste containing both frangible
and malleable material such as light bulbs 26 to a crushing apparatus 30
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where the objects are crushed. The crushed material is then separatedby a particle screen 60 into frangible and malleable particles in
preparation for recycling. Although expired incandescent light bulbs 26
are illustrated throughout as the subject of the apparatus, other mixed
waste containing frangible and malleable materials may also be
processed.
Frangible material such as glass is more brittle than metal. When
the brittle material passes through the crushing apparatus 30, it is
shattered and thereby broken into small grains and fines. Metal, on the
other hand, particularly comparatively ductile metals such as lead or
copper, is not fractured on passing between the compressive rollers, but
is instead flattened out into enlarged narrow waste elements.
Frangible and malleable materials will respond differently to
crushing. A light bulb 26 containing both frangible and malleable
material, shown in the drawing, is first broken into pieces as it moves
through the waste stream. However, these pieces may not be
distinguishable on the basis of size, including small dense metal
elements, as well as large thin glass shards. Once crushed the glass is
broken down into very small glass particles 72 which are distinguishable
and may be separated from the possibly environmentally hazardous lead
which is flattened or elongated during the crushing process.
As shown in the drawing, the crushing apparatus 30 receives
waste material 24,made of both frangible and malleable materials from a
conveyor 22 or other distributing device which supplies an even flow of
material to the roll couple 32. The roll couple includes rolls 34 and 36,
which are disposed in a housing 40 having a top opening 42 through
which the mixed waste 24 enters, and a bottom opening 44 through
which the crushed material flows from the apparatus. The roll couple 32
has two rolls 34, 36 which are approximately three feet in diameter and
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which rotate toward one another and which are closely spaced from oneanother at a nip 50. The nip is preferably about an eighth of an inch
wide. As the rolls 34, 36 rotate toward each other, mixed waste which
is deposited on the upper surfaces of the rolls will be advanced to pass
through the nip 50.
The crushing apparatus in a preferred embodiment is similar to the
DynaYield Chip Conditioner manufactured by Rader Companies of Beloit
Corporation. However, although a DynaYield Chip Conditioner employs
aggressively contoured rolls, typically having a multitude of pyramidal
projections, as disclosed in U.S. Patent No. 4,953,795, the rolls 34, 36
preferably are smooth or have a moderately aggressive contoured
surface. Furthermore, although cast iron or steel rolls or roll surfaces are
employed for wood chip cracking applications, the rolls or roll surfaces of
the crushing apparatus 30 are preferably composed of polyurethane.
The crushing apparatus rolls apply compressive force to light bulbs
or other objects made of frangible and malleable materials that pass
therebetween. The objects are compressed between the roll surfaces,
crushing the frangible material and flattening or elongating the malleable
material.
The crushing apparatus 30 has electric motors which drive speed
reducers by matched V-belts. The speed reducers are connected to the
central drive shafts of the rolls 34 and 36. The rolls 34 and 36,
together with their bearings and speed reducers, are horizontally
adjustable by means of hydraulic actuators (not shown). These control
the width of the nip 50 by moving the first roll 34 in spaced parallel
relation to the opposed roll 36. The hydraulic actuators also allow the
rolls 34, 36 to separate in response to larger foreign objects to decrease
the likelihood of damage to the roll surfaces.
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It should be understood that the arrangement shown in the
drawing, is merely one example of a suitable arrangement. In some
installations, it may be desirable to use two or more roll couples.
The mixed waste stream leaving the crushing apparatus 30 is now
comprised of larger particles 74 of malleable material, which have not
been broken up by the crushing process, and smaller particles 72 of
frangible material which are reduced in size by the crushing process.
The mixed waste is fed to a screening device 60 to separate out the
particles on the basis of size.
Any appropriate screening apparatus may be used, for example
bar screens, disc screens, vibrating screens, or gyratory-type screens
which employ a rotary screen with an eccentric underneath, to cause the
oscillation thereof. An exemplary screening device 60 is similar to the
wood particle screen disclosed in U.S. Patent No. 5,037,537. The
screening device 60 has a bed of flexible, foraminous material with holes
sized to permit only those particles smaller than an acceptable size range
to pass through. Crushed mixed waste 68 is introduced through an inlet
chute 70 at an inlet end 62 of the screen 60. Small frangible particles
72 pass through a screening bed 80 formed by a foraminous screen 66
and are removed on a frangible material conveyor 76, and those larger
particles 78 not passing through the screening bed are ejected from the
outlet end 64 of the screening bed and removed on a malleable material
conveyor 78.
, . .
A plurality of beater rolls 96 are disposed beneath the flexible
screen 66, each including a plurality of spaced beater bars 92, 94 so
positioned to cyclically strike the underside of the flexible screen 66.
The beater rolls 96 are driven by a drive mechanism 89. Contact
between the beater bars 92, 94 and the foraminous, flexible material of
the screening bed causes larger particles to dance along the surface of
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the screening bed, contacting the surface only briefly before being
accelerated away from the bed; while the smaller, lighter materials can
quickly pass through the screen.
The assembly 20 thus advantageously makes possible a
separation of materials based on their level of malleability, converting the
different materials into different sized particles which are easily
separated.
It should be understood that the invention is not limited to the
particular construction and arrangement of parts herein illustrated and
described, but embraces such modified forms thereof as come within the
scope of the following claims.
