Note: Descriptions are shown in the official language in which they were submitted.
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MAGNETIC DRUM SEPARATOR
FIELD OF THE INVENTION
The present invention involves material separators which
separate particulate material into components thereof based
upon the magnetic properties of such components.
Specifically, the present invention concerns magnetic drum
separators having a high field strength magnet assembly
disposed internally of a drum so that, as material is advanced
by the sidewall surface of the drum, differing trajectories
are imparted to the components based upon differing magnetic
attraction to the magnetic array.
BACKGROUND OF THE INVENTION
A processing step of separating an aggregate material
into various components has proved highly valuable in modern
industrial processes. Many different separation techniques
have been utilized in the past with these techniques relying
on differing characteristics of the components of the
aggregate, such as size, weight, specific gravity, solubility
in different solvents, etc. The separation of a particulate
material into magnetic and non-magnetic components has
particular utility. Among various magnetic separation
apparatus, two particular assemblies enjoy wide-spread use in
the dry and wet separation of particulate materials.
A first type of magnetic separation apparatus is known as
a high-intensity magnetic roll separator. Typically, a
magnetic roll separator is configured to have a cylindrical
magnetic roller located at a downstream end and a cylindrical
idler roller located an upstream end. A relatively thin
conveyor belt encircles the magnetic roller and the idler
roller to convey the particulate material for discharge at the
magnetic roller end. Particulate material is deposited at an
upstream end of the belt and advanced towards the downstream
end and discharged as the conveyor belt moves around the
magnetic roller. Magnetic components are attracted to the
magnetic roller and thus have a different discharge
trajectories than non-magnetic components. An example of such
a magnetic roller assembly is shown in my U.S. Patent No.
5,101,980 issued April 7, 1992.
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A second type of magnetic separation apparatus is known
as a drum separator. A typical drum separator is constructed
to have a drum formed as a cylindrical shell which is
rotatably journaled onto a horizontal axis. Particulate
material is introduced on the outer cylindrical surface of the
drum and, as the drum rotates, this particulate material is
advanced and is discharged under the force of gravity so as to
have a discharge trajectory. A magnetic array is disposed
internally of the drum and is located proximate to the drum
sidewall. The magnetic array is positioned to interact with
the particulate material before it is discharged from the drum
surface. Thus, as the particulate material moves past the
.° magnetic array, the magnetic attraction between certain
components of the particulate material tend to adhere to the
drum surface longer than non-magnetic components. Moreover,
different magnetic components of the aggregate have varying
strengths of interaction with the magnetic field from the
magnet array so that the differing magnetic components as well
as non-magnetic components have different discharge
trajectories from the drum due to a combination of tI-~
magnetic force and the gravitational and inertial forces. The
differing streams of particulate materials may be separated by
simple partition walls either in chutes, bins or the like, and
the separated components may be further processed and refined
w for purity.
The present invention is directed to this second type of
magnetic separation apparatus and provides advantages over
existing magnetic drum separators. For example, one
difficulty in the construction of magnetic drum separators is
the organization of a magnetic array which provides a magnetic
field of sufficient strength to adequately interact with the
magnetic components of the feed material. Whereas magnetic
roll separators are able to use conveyor belts which are
relatively thin and flexible, the drum of a magnetic drum
separator must be of sufficient mechanical strength and
rigidity to minimize deflection of the drum sidewall for large
drum separators and otherwise to support the weight of the
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particulate material (usually crushed ore). This requires the
drums to be constructed of a non-magnetic metal or a non-
conductive material having a sufficient sidewall thickness to
provide the requisite structural integrity. By having a
thicker sidewall, the particulate material is by necessity
located an increased distance from the magnetic array than
that achieved, for example, by the magnetic roll separator.
This of course diminishes the strength of the magnetic field
at the outer surface of the drum.
Further, due to the typical construction of the rotating
drum sidewall out of a non-magnetic metal material, the
movement of the sidewall through the magnetic field causes the
induction of eddy currents having their own electric magnetic
field components. Since the force of these fields interacting
with the magnetic field from the magnetic array must be
overcome by the mechanical drive for the drum itself, the
support structure for the magnetic array and the drum must be
adequately designed, especially where the magnetic array
provides superior magnetic field strength.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new
and useful magnetic drum separator which is adapted to
separate particulate aggregate material into components of
differing magnetic properties.
Another object of the present invention is to provide a
magnetic drum separator which has a magnetic array that
provides enhanced magnetic field strength.
A further object of the present invention is to provide
a magnetic drum separator which is easy to assemble yet which
provides magnetic array that produces relatively high magnetic
field strength.
Still a further object of the present invention is to
- provide an improvement to existing magnetic drum separators
which improvement comprises a magnetic array constructed to
have improved field strength characteristics.
According to the present invention, then, a magnetic drum
separator is adapted to receive particulate material thereon
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in order to separate the particulate material into different
components having different magnetic properties. Broadly, the
magnetic drum separator includes a support frame and a drum
rotatably journaled with respect to the support frame on a
longitudinally extending rotational axis. The drum has an
outer sidewall formed as a cylindrical shell out of a selected
material so as to have an open drum interior. A magnetic
array is disposed in the drum interior, and the magnetic array
is fixed relative to the support frame.
The magnetic array is configured to have an arcuate
active surface which is oriented in closely-spaced relation to
the drum sidewall with the magnetic array operative to produce
a magnetic field at the active surface. The magnetic array
includes a plurality of longitudinally extending bars which
are circumferentially spaced from one another and which are
formed out of a ferromagnetic material. A longitudinally
extending first magnet is interposed between circumjacent ones
of these bars and, preferably, a longitudinally extending
second magnet is associated with each of the bars with the
second magnet being located radially inwardly of a respective
bar in the interior of the drum. A drive is then mechanically
connected to the drum and is operative to rotate the drum on
the rotational axis so that the drum sidewall moves past the
magnetic array.
Preferably, circumjacent ones of the first magnets have
north and south magnetic poles aligned perpendicularly to a
radial direction relative to the drum with similar magnetic
poles of the circumjacent ones facing one another with a
respective bar disposed therebetween. Here also, it is
preferred that the second magnets have north and south
magnetic poles aligned with the radial direction and that the
second magnet located between circumjacent ones of the first
magnets have a similar magnet pole facing the respective bar
between the circumjacent first magnets. Moreover, it is
preferred that each of the first magnets each be constructed
out of a plurality of discrete magnetic elements which are
arranged stack-wise in the longitudinal direction. Likewise,
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each of the second magnets may also be formed of a plurality
of discrete second magnetic elements. In any event, it is
preferred that both the first and second magnets be
constructed of a rare earth alloy material.
In the magnetic separator, it is preferred that a rigid
axle member be disposed in the interior of the drum and that
the drum be rotatably journaled on bearings at either end of
the rigid axle member. The magnetic array is then mounted
between a pair of support brackets rigidly connected to the
axle member in the interior of the drum, with each of these
support brackets being formed by a pair of bracket sections
that are adjustable with respect to one another to allow a
degree of adjustment in the positioning of the magnetic array.
An arcuate support plate may be connected to each of the
support brackets to extend therebetween and to support the
magnetic array at a radially inward location. The
longitudinally extending bars may be connected at opposite
ends to the support brackets and may also be connected to the
support plate. Each of these bars may be trapezoidal in
cross-section with a pair of oppositely and circumferentially
projecting flanges to retain the first magnets therebetween.
These first magnets may be supported against the support plate
by means of longitudinally extending spacer bars which are
connected at opposite ends to the support brackets. The
second magnets may then be sandwiched between the support
plate and the longitudinally extending bars, and retaining
channels may be formed longitudinally in the support plate to
nestably receive the second magnets.
Opposite annular ends may enclose the interior of the
drum with these annular ends being rotatably journaled on
bearings mounted to the rigid axle. A drum drive shaft may be
interconnected to one of these annular ends and the drive with
the drum drive shaft being rotatably journaled with respect to
the frame on a shaft bearing.
The magnetic array may be selected to extend a selected
arcuate distance around the axle member. Preferably, the
active surface of the magnetic array is arcuate in shape and,
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to this end, the outer surfaces of the longitudinally
extending bars which form part of the magnetic array are
arcuate in shape. The array extends preferably at least 45°
of arc about the axle, although it is preferred that the
active surface of the magnetic array extend in a range of
between 75° and 120° of arc, inclusively.
According to one aspect of the present invention,
there is provided a magnetic drum separator which receives
particulate material thereon in order to separate said
particulate material into different components having
different magnetic properties, comprising: (a) a support
frame; (b) a drum rotatably journaled on a longitudinally
extending rotational axis with respect to said support
frame, said drum having a drum sidewall formed as a
cylindrical shell out of a first material and having a drum
interior; (c) a magnetic array disposed in the drum interior
and fixed relative to said support frame, said magnetic
array having an arcuate active surface oriented in closely-
spaced relation to said drum sidewall and operative to
produce a magnetic field at the active surface, said
magnetic array including a plurality of longitudinally
extending bars circumferentially spaced from one another and
formed of a ferromagnetic material, a longitudinally
extending first magnet interposed between circumjacent ones
of said bars and a longitudinally extending second magnet
associated with each of said bars, each said second magnet
located radially inwardly of its respective said bar in the
interior of said drum, each said second magnet having a
central longitudinal axis and positioned within the interior
so that the central longitudinal axis intersects a radial
line passing through an associated one of said bars; and
(d) a drive operative to rotate said drum on the rotational
axis so that said drum sidewall moves past said magnetic
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array so that particulate material placed on an outer
surface of said drum is subjected to the magnetic field
whereby components of said particulate material having
different magnetic properties will discharge off of said
outer surface with differing trajectories.
According to another aspect of the present
invention, there is provided a magnetic drum separator which
receives particulate material thereon in order to separate
said particulate material into different components having
different magnetic properties, comprising: (a) a support
frame; (b) a drum rotatably journaled on a longitudinally
extending rotational axis with respect to said support
frame, said drum having a sidewall formed as a cylindrical
shell out of a first material and having a drum interior;
(c) a rigid axle member disposed in the interior of said
drum along the rotational axis; (d) a pair of longitudinally
spaced-apart brackets oriented in planes perpendicular to
the rotational axis and rigidly secured to said axle member;
(e) a longitudinally extending arcuate support plate secured
between said brackets so as to be oriented concentrically
with respect to said drum sidewall and spaced radially
inwardly thereof; (f) a plurality of longitudinally
extending bars circumferentially spaced from one another and
formed of a ferromagnetic material, said bars each secured
at opposite bar ends to said brackets and spaced radially
outwardly of said support plate; (g) a plurality of
longitudinally extending first magnet means for creating a
magnetic field, there being a respective first magnet means
interposed between adjacent ones of said bars and supported
against said support plate, said first magnet means each
having an outer first magnet surface and said bars each
having an outer bar surface such that the outer first magnet
surfaces and the outer bar surfaces forming an arcuate
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active surface oriented in closely spaced relation to said
drum sidewall; and (h) a drive operative to rotate said drum
on the rotational axis so that said sidewall moves past the
active surface so that particulate material placed on an
outer surface of said drum is subjected to a magnetic field
whereby components of said particulate material having
different magnetic properties will be discharged off of said
outer surface with differing trajectories.
According to still another aspect of the present
invention, there is provided in an apparatus which separates
a particulate material into different components according
to different magnetic properties wherein a drum has a
sidewall formed as a cylindrical shell and is journaled for
rotation relative to a support structure on a longitudinal
axis with the drum having an open drum interior, the
improvement comprising a magnetic array disposed in the drum
interior with said magnetic array formed of a plurality of
longitudinally extending bars circumferentially spaced from
one another and constructed of a ferromagnetic material and
a plurality of longitudinally extending first permanent
magnets, there being one of said first permanent magnets
disposed between circumjacent ones of said bars, said bars
and said first magnets having a generally arcuate active
surface disposed in close-spaced facing relation to an inner
surface of said sidewall, said magnetic array further
including a second magnet associated with each of a majority
of said bars, said second magnets each located radially
inwardly of a respective bar and extending longitudinally
therealong, said second magnets having a polarity extending
in a radial direction, said magnetic array positioned such
that particulate material on an outer surface of said
sidewall will be influenced by magnetic forces from said
magnetic array as said sidewall is advanced thereon.
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According to yet another aspect of the present
invention, there is provided a magnetic drum separator which
receives particulate material thereon in order to separate
said particulate material into different components having
different magnetic properties, comprising: (a) a support
frame; (b) a drum rotatably journaled on a longitudinally
extending rotational axis with respect to said support
frame, said drum having a sidewall formed as a cylindrical
shell out of a first material and having a drum interior;
(c) a rigid axle member disposed in the interior of said
drum alone the rotational axis; (d) a pair of longitudinally
spaced-apart brackets oriented in planes perpendicular to
the rotational axis and rigidly secured to said axle member;
(e) a longitudinally extending arcuate support plate secured
between said brackets so as to be oriented concentrically
with respect to said drum sidewall and spaced radially
inwardly thereof; (f) a plurality of longitudinally
extending bars circumferentially spaced from one another and
formed of a ferromagnetic material, said bars each secured
at opposite bar ends to said brackets and spaced radially
outwardly of said support plate; (g) a plurality of
longitudinally extending first magnet means for creating a
magnetic field, there being a respective first magnet means
interposed between adjacent ones of said bars and supported
against said support plate, said first magnet means each
having an outer first magnet surface and said bars each
having an outer bar surface such that the outer first magnet
surfaces and the outer bar surfaces forming an arcuate
active surface oriented in closely spaced relation to said
drum sidewall; (h) a plurality of second magnet means, there
being a second magnet means disposed between said support
plate and each of said bars for augmenting the magnetic
field; and (i) a drive operative to rotate said drum on the
rotational. axis so that said sidewall moves past the active
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surface so that particulate material placed on an outer
surface of said drum is subjected to a magnetic field
whereby components of said particulate material having
different magnetic properties will be discharged off of said
outer surface with differing trajectories.
These and other objects of the present invention
will become more readily appreciated and understood from a
consideration of the following detailed description of the
exemplary embodiment when taken together with the
accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a magnetic drum
separator according to the exemplary embodiment of the
present invention;
Figure 2 is a side view in partial cross-section
showing the drum and drum supports of the magnetic drum
separator shown in Figure 1;
Figure 3 is a cross-sectional view taken about
lines 3-3 of Figure 2;
Figure 4 is an exploded view in perspective
showing the support bracket for the magnetic array shown in
Figures 2 and 3;
Figure 5 is an end view of a portion of the
magnetic array shown in Figure 3;
Figure 6 is a cross-sectional view taken about
lines 6-6 of Figure 5;
Figure 7 is an end view in cross-section of a
portion of the magnetic array shown in Figures 2 and 3;
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Figure 8 is a cross-sectional view taken about
lines 8-8 of Figure 7; and
Figure 9 is a diagrammatic view showing the
organization of the magnetic poles of the magnetic array of
Figures 2 and 3.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT
The present invention is directed to a magnetic
drum separator which is useful in the separation of
particulate,
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aggregate material into different components which have
different magnetic properties. This invention may be used
with both dry material, wet material and slurried material
where components of differing magnetic properties are present.
Accordingly, the present invention is particularly useful as
initial separation process for treating finely crushed ore or
other materials.
With reference first to Figure 1, it may be seen that
magnetic drum separator 10 includes a drum 12 rotatably
journaled on a rotational axis "R". Rotation is imparted, for
example, by means of an electrical drive motor 14 acting
through gear box 16, which turns drum drive shaft 18 through
coupler 20. Drum 12 is rotatably journaled on a framework 22
with rotational axis "R" preferably being oriented
horizontally. Particulate matter may be introduced onto the
outer surface of drum 12 at an upper location, for example, by
means of chute 24. In Figure 1, it may be seen that
representative particulate material is introduced as feed "F"
with drum 12 being rotated in the direction of arrow "A".
With reference to Figure 2 and 3, it may be seen that
drum 12 is formed as a hollow cylindrical shell having a
sidewall 26 formed of any material suitably strong and rigid
so as to be able to support the particulate material during
processing. Sidewall 26 may be constructed for example, of
non-magnetic steel or other metal or any other suitably strong
and rigid non-conductive material. Accordingly, sidewall 26
has a cylindrical working surface 28 onto which the
particulate material is placed. Annular drum end castings 30
and 31 along with drum sidewall 26 enclose a relatively open
interior 32 of drum 12, and it may be seen in Figure 2 that
end castings 30 and 31 are rotatably supported by bearings 34
on a stationary or static shaft 36. A first end 38 of shaft
- 36 is rigidly supported by shaft clamp block 40. Clamp block
40 is in turn supported on framework 22. Shaft seal ring 44
is mounted to the end casting 30 to provide a sealing contact
with shaft 36 when drum 12 is rotated.
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A second end 46 of shaft 36 is rotatably supported by
bearing 34 on end casting 31. Drum drive shaft 48 is secured
by means of bolts 50 to end casting 31, with drive shaft 48
having a shank 52 rotatably mounted in plummer block 54 that
supports bearing 56 on framework 22. Drum drive shaft 48 is
then mechanically connected to drive shaft 58 from gear box 16
by means of drive shaft coupling 20, as noted above.
With reference to Figures 2 and 3, it may now be
appreciated that a magnetic array 60 is disposed in interior
32 of drum 12. Here, magnetic array 60 has an arcuate active
surface 62 and is supported radially by means of a pair of
brackets 64 and 70 and an,arcuate support plate 72. Support
plate 72 extends longitudinally of drum 12 between brackets 64
and 70 so as to be concentric with drum sidewall 26. Active
surface 62 is therefore in closely spaced concentric relation
with sidewall 26 inner surface 29 as sidewall 26 rotates past
active surface 62 of magnetic array 60.
To accomplish this positioning, each of brackets 64 and
70 is formed by a pair of sections. Thus, an exemplary
bracket 64 is shown in Figure 4 and includes an inner bracket
piece 66 and an outer bracket piece 68 which may be bolted
together by means of bolts 74 extending through slots 76 in
bracket piece 66 to engage threaded bores 78 in bracket piece
68. The provision of slots 76 in inner bracket piece 66
allows for a modest amount of radial adjustment of support
plate 72 and magnetic array 60. Inner bracket piece 66 is
then affixed to shaft 36 for example, by weldments 80.
Bracket 70 is constructed similarly as bracket 64 and has
inner bracket piece 82 and an outer bracket piece 84 with
inner bracket piece 82 being affixed to shaft 36, for example,
by weldments 86.
The construction of magnetic array 60 may now be more
fully understood, especially with reference to Figures 3-8.
Here, it may be seen that support plate 72 is connected
between brackets 64 and 70 by bolts 88 received in threaded
bores 90 of support plate 72. A plurality of longitudinally
extending bars 92 have arcuate outer surfaces 93 and have
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opposite ends bolted to brackets 64 and 70 by means of bolts
94 extending, for example, through holes 96 in outer bracket
piece 68 to be threadably received in threaded bores 98 of
each bar 92. As is shown in Figure 3, bars 92 are
circumferentially spaced from one another with the outer bars
92' providing the longitudinally extending lateral edges for
magnetic array 60.
A plurality of first magnets 100 extend longitudinally of
magnetic array 60 and are interposed in abutting relationship
between a pair of circumjacent bars 92. As is shown in Figure
8, each of first magnets 100 is actually formed by a plurality
of magnetic elements 102 organized and stack-wise relation in
the longitudinal direction. Each magnetic element 102 of
first magnets 100 is supported by a longitudinally extending
spacer bar 104 interposed between support plates 72 and first
magnets 100, as best shown in Figure 7. Spacer bars 104
extend between brackets 64, 70 and are connected thereto by
means of bolts 106 extending through holes 108, for example,
in outer bracket piece 68 and received in threaded bores 110
in the opposite ends of spacer bar 104. Support plate 72 an
spacer bars 104 may be constructed of any suitable material,
but aluminum is preferable due to cost and weight
considerations.
As is best shown in Figure 5, each bar 92 is generally
trapezoidal in cross-section but has a pair of oppositely
projecting flanges 112 so that magnets 100 are confined
between spacer bars 104 and flanges 112 of an adjacent pair of
bars 92. As noted above, each bar 92 extends longitudinally
between brackets 64, 70 and are secured by means of bolts 94
thereto. Bars 92 are also secured to spacer bar 72 as is best
shown in Figure 6. Here, it may be seen that a plurality of
bolts 114 extend through holes 116 formed radially in support
plate 72 with the ends of bolts 114 being threadably secured
in threaded bores 118 extending radially into each spacer bar
92. With reference to Figures 5 and 6, it may be seen that a
second magnet 120 provides a magnetic means associated with a
majority of bars 92 with second magnets 120 being interposed
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in abutting relationship between a respective bar 92 and
support plate 72 so that each is located radially inwardly of
a respective bar and extends longitudinally therealong. To
this end, support plate 72 is provided with a plurality of
longitudinally extending shallow channels 124, such as that
shown in Figure 5, to help locate each second magnet 120.
- Moreover, as is best shown in Figure 6, each second magnet 120
may actually be provided by a plurality of second magnetic
elements 122 which are separated by spaces 123 to accommodate
bolts 114, noted above.
It may be appreciated that the organization of first
magnets 100, second magnets 120 along with bars 92, 92'
provide a superior magnetic field for magnetic drum separator
10. To this end, each magnetic element 102 of first magnets
100 as well as each magnetic element 122 of second magnets 120
are high field strength rare earth alloy magnets. It should
be understood, however, that other magnets, such as ceramic
ferrite magnets, rare-earth magnets and the like, could be
employed depending on the field strength desired. Bars 92,
92' are constructed of low carbon steel or any suitable
ferromagnetic material and act to help focus the magnetic
fields from magnets 100, 120. Further, it should be
appreciated by the ordinarily skilled person in this field
that the circumferential width, profile shape and number of
bars 92, 92' as well as the size and number of the magnets
100, 120 can be varied to achieve a desired magnetic strength
and number of magnetic poles as different applications may
require without departing from the scope of this invention.
With reference to Figure 9, it may now be seen that
arrows 130, 132 show the direction of the magnetic poles of
magnets 100 and 120 with the head of arrows 130, 132
indicating a magnetic north. In Figure 9 it may be seen that
magnets 100 have magnetic poles that are oriented
perpendicularly to the radial direction with like poles of
each circumjacent magnet 100 facing one another with a bar 92
located therebetween, that is, circumjacent ones of magnets
100 have oppositely oriented polarities. Moreover, each
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magnet 120 has magnetic poles extending radially with the
direction of such poles alternating for each circumjacent
magnet 120, that is, circumjacent ones of magnets 120 have
oppositely oriented polarities. Here, also, it may be seen
that each magnet 120 has a magnetic pole contacting bar 92
that is the same as the magnetic poles of magnets 100 that
face that respective bar 92.
From the foregoing, and in reference to Figure 9, it may
be appreciated that each adjacent bar 92 has alternating
polarity and is at high magnetic flux due to the organization
of magnets 100 and 120. Thus, a very high magnetic field
strength, approximating 0.3 to 2.2 Tesla, extends along active
surface 62 with this magnetic flux extending arcuately between
each adjacent arcuate surface 93 of the adjacent bars 92.
In operation, an aggregate material may be conveyed by
the outer surface of drum 12. In this manner, it is advanced
by sidewall 26 so that it moves past magnetic array 60 which
has its arcuate active surface 62 oriented in close-spaced
facing relation to the inner surface of sidewall 26.
Particles in the aggregate material which have no magnetic
property will discharge from drum 12 with a trajectory
depending solely upon gravitational and inertial forces.
However, those components which are magnetic will tend to
adhere to the surface of drum 12 due to the presence of
magnetic array 60. Thus, the magnetic components will have a
different trajectory based on the combination of the magnetic
force with the inertial and gravitational forces. Moreover,
where the magnetic components differ in degree of magnetism,
these components will likewise have a different amount of
interaction with magnetic array 60 and therefore have
different trajectories as well.
While the above invention has been described specifically
with respect to the magnetic separation of aggregate material
which is often in dry particulate form, it should be
understood that the present invention is not limited to just
a separation of dry materials. Indeed, the drum and magnetic
array may be suitably oriented to receive wet, slurried
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materials which may also be separated by array 60 into
magnetic and non-magnetic components. All that is necessary,
as the ordinarily skilled artisan will realize, is the
provision of the necessary troughs to hold the slurried
material as well as the proper positioning of magnetic array
60 relative to the slurry material, all as is known in the
art.
Accordingly, the present invention has been described
with some degree of particularity directed to the exemplary
embodiment of the present invention. It should be
appreciated, though, that the present invention is defined by
the following claims construed in light of the prior art so
that modifications or changes may be made to the exemplary
embodiment of the present invention without departing from the
inventive concepts contained herein.
