Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~701~7
E,ACKGROU D OF TIT.E INVENTIO~I
In the art of recovering waste materials and, more
particularly, mixed waste materials as well as industrial
processing trim, rejects, scrap, punching trim, laminatecl
waste ancl especially waste containing at least one thin
sectioned product, prior metals separating art has en-
countered difficulty in effecting separation by the usual
properties of magnetism, density, and size.
Platelets contained in shredded waste do not res-
pond well to the air flotation and vibratory conveying
actions of conventional separation "gravity tables.
Platelets may, after cutting, remain flat or may be
rumpled, folded, or rolled into tubes or other forms
which give no constant and precdictable "apparent den-
sity" or "apparent specific gravity" which is the prop-
erty enabling separation to occur on the "gravity table"
separators.
Furthermore conventional art can satisfactorily
effect certain separations, such as separating shredded
waste toothpaste tubes from residual paste, plastic caps
and iron closure clips, but such thin walled flake-like
product is of very low value because it is so bulky to
handle, so poor a heat exchanger that it melts slowly in
remelt furnaces and oxidizes to a damaging degree in so
cloing because of the great surface area exposed to the
heat and air. ~eer, motor oil, and soft drink cans sim-
ilarly may be reclaimed from mixed wastes by hand sorting,
but also represent high labor cost and low valued pro-
ducts because of similar reasons plus the fact that if
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they are not shredded and merely baled or briquetted, the
contained moisture, residual product, dirt, ink enamel
contamination, and foreign metal and non-metal contamin-
ation lowers the value even further.
In addition to the above mentioned, other examples
of waste having thin walled components are: coaxial cable,
heat exchanger tubin~ consisting of thin walled copper
and aluminum and sometimes solder, printed circuit boards
and other metal-plastic laminates, assorted electronic
circuit assemblies, condensers, transformers, canned
relays and condensers, and future mixed metal and plastic
laminates currently being tested for solar heating systems.
Prior reclaimed metals separation art, using the dry
process, consists essentially of the general steps of:
(1) ~ross manual separation (2) reduction to airveyable
size and polishing the discrete particles (3) magnetic
separation of iron (this may occur at several locations)
(4) parti~le sizing by grading screens and (5) specific
gravity separations.
Separations are based on magnetic removal of iron
and on differences of specific gravit~ or density of
whatever shaped particles are being separatQd. ~ecause
particle shapes vary so greatly, we use the terms
"apparent density'l or "apparent specific gravity`'. An
air blast acts differently on a flat platelet or short
piece of fine wire than it does on a denser round sphere.
This makes possible the separation of fine wire or
platelets or flakes from coarser wire and other denser
~1170~
shapes of the same metal having higher apparent density.
Since this is not the goal of the recovery system, it becomes
a handicap because the flak~s and fine wires of copper may
float along with larger but heavier, higher apparent density
aluminum particles.
Prior art provided no method for efficiently
making separations of all unlike shapes of different
materials.
One aspect of the invention resides in a method
which includes the step of reducing the mixed materials to
feedable particulate size. The mixed materials are conveyed
to an impact area by a conveying air flow, and the particles
are impacted to deform them into spheriod shapes by striking
them with one surface thereby projecting them in free flight
fashion at high velocity against another surface, the
respective surfaces being non-contacting relative to each
other and separated by a minimum distance greater than the
maximum dimension oE the feed material particles. The
spheroidal particles are withdrawn and are conveyed and collected
for grading the spheroidal particles by size. Similarly
sized spheroidaL particles having different apparent specific
gravities by use of a specific gravity table means, and
the separated fractions are collected.
According to another aspect of the present
invention there is provided an apparatus for converting
irregularly shaped malleable feed material into spheriodal
shape, the apparatus including a retaining case with means
for feeding particles by a gaseous conveying fluid at a
controllable and constant feed rate and ratio into the case.
Means is provided for controlling the flow of conveying air
through the case, and impacting means is provided
for continuously and repetitively projecting the particles
in free flight and at a high velocity against target surfaces. The
impacting means includes a driven rot~ry impeller
tm ~! 3
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having abrasion resistant blade tips rot~ting at 5,000
to 20,000 surface feet per minute in spaced relationship
with a substantially enclosed circularly sectioned liner in
the case. The target surfaces include abrasion resisting
transverse rib members on the liner, the blade tips
being spaced fr~m the rib members by a distance greater
than the maximum dimension of the feed material. The liner
is provided with one or more exit ports enabling the particles
to be withdrawn from the case.
The subject process eliminates the mixed shape
separation problems by converting all materials which are to
be separated on the gravity tables to roughly spherical
lumps or spheroids and thereafter grading them to size.
Thus the gravity tables are comparing the apparent specific
gravities of metals in comparative shapes and sizes and
thus ellminate the dissimilarities caused by odd shapes.
Added advantages consist in the fact that when fine wire
is spherized, it no longer is inclined to plug the sizing
and separator screens as it usually does. Aside from the
advantages of processing the spherized material during
separation, there is an added valuable advantage in the fact
that the end product(s) are dense free-flowing easier melting
polished metal shot which brings a premium price on the
market. Since the separations are much more efficientr
the analysis also may be held to closer tolerances, giving
further reason to command a premium market price.
In practicing the sub-iect process, feed materials
are processed in the same manner as used in prior art
except that after reduction to size, the material may in
some cases be fed directly to the spherizer and then,
after grading or sizing, to the gravity tables. In case
there is too much ex-traneous matter such as insulation,
tm,~l ''J -4-
11~7(~7
this may be removed on a gravity table before passing the
metal to the spherizer. Sizing and separations of similarly
sized fractions follow us with prior art.
Thus, it should be emphasized that the use of
the spherizing step may be variably introduced into the
sequence of the operation depending upon the material
mixture being processed. The use o~ spherizing before
final separation is the only critical feature of the
sequence of the process. The contribution to the art of
this process consists essentially in its ability to effect
more efficient separations and to produce a better physical
shape or form of the product based at least partly on the
differences in ductility and/or malleability of different
metals or alloys thereof.
It is essential to understand the uniqueness of the
mechanism and its action in producing a spheroid particle
of metal or other malleable or ductile material in order
to understand the process.
An interesting feature of the invention is that
a thin particleis crumpled a little each time it is struck
plus the fact that a free moving particle of irregular
shape will align itself, as a dart does, with its least dense
part in the rear, so that each blade blow crushes the
most irregular part of the particle and thereby forms
a roughly spherical or spheroided particle. This concept
seems to explain the results obtained; but since the
explanatior fo1lowed the discovery ~ ~he method and was
suggested by another person, it is only submitted to
help understand the process.
The degree of densification varies with the malle~
ability of each metal or alloy. Platelets of shredded
electrical assemblies containing spring bronze relay
tm/~ S-
,, ~
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arms mixed with copper, aluminum, and brass terminal
strips may be spherized. The hard bronse will respond
least to the impacting while the soft copper will form the
densest shot of spheres. ~luminum in most of its form
works harden more than copper so it is inclined to form
less dense spheres. Most brasses respond well but some
hard brasses may be separated from softer grades.
The above generalizations change at elevated
temperatures. A mill with a 42" diameter rotor can work
heat particles to red heat if operated at high speeds (e.g.
1200 rpm). At such temperatures ~ost metals are annealed
tm/~ 5a-
and hecome ductile and form dense spheroids. By control
of temperature and speecl, metals having differing anneal-
ing temperatures may be processed. For maximum flexi-
bility, efficiency, and safe~y, it is advisable to pro-
vide temperature controls. This may be easily accomplish-
ed by circulation of heated or cooling air in suitable
channels in the framing and control of throughput air
volumes. The cooling air may simply be circulated as
coolant or may be used as a means of assisting in con-
veying the finished product. When elevated temperatures
are desirable or a controlled non-oxidizin~ fluid is
preferred to air, such may be re-circulated through the
jacket ducts and then separated from the end product
at a cyclone and be re-circulated repeatedly. Added
advantages result from use of "burned air" as a carrier
fluid when processing magnesium-containing products
which are otherwise hazardous.
Definitions
T'ne following terms as used herein are defined as
followS:
malleable material: Material which may be permanently
formed or deformed by the blow of a tool or other impact.
: A shape roughly approximating a sphere such
as a hammered particle.
spherizer: A machine which beats or impacts other
shapes into spheroidal shape. E.G. short pieces of
cylindrical or square wire, shredded sheet, fragments
of granulated aluminum or other metal casting or plate,
as well as certain malleable plastic particles.
granulator: A multi-pladed rotor turning within a case
likewise equipped with blades as well as a size con-
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trolling exit screen used to chop or cut plastics,
softer metals and the like into granules. ~ machine
used to reduce material to a clesired granular size.
~ ules: Small particles which are airveyable or other-
wise easily bulk handlea and fed. Sizes roughly range
from a maximum dimension of 1 " to a minimum of 1/16".
Below that size it can be called a powder.
~ actin~: This term is used in an effort to avoid
other connotations of the word "beatingl' which implies
the existence of an anvil or other support. The word "swat"
would be more descriptive but perhaps unacceptable. The in-
tent is to express bo~h the blow of a moving surface as it
strikes a free falling particle and also the collision of a
projected particle against a stationary or counter rotation
target.
_zing: Grading on a stacked or other screen as to size.
Reduction to size may be grinding in a granulator.
apparent density: (Also apparent specific gravity) The
specific gravity of a porous or hollow spheroid as contrasted
to the true specific gravity oE the metal which forms the
shape.
shot: A roughly spherical particle - usually solid in
section. Shot results from melting metal and dropping it
through an air space or a dense particle approaching shot
can be formed in a spherizer when a red hot fully annealed
particle is impacted suitably. Its density then approaches
true metal density.
specific gravity tables: Are well known by the semi-
precious metals reclaiming trade and one form consists of
an uphill conveying shaker table combined with an upflow of
air through the screen bottomed conveying table which gives
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a simultaneous fluidized bed effect. These result in the
heavier fractions climbing uphill and out while the lighter
material flows downward and out a separate clischarge port.
The air lifting efect is erratic with non-spherical shapes
and very effective with spherical mixtures of similar size.
The apparent specific gravity of a particle determines
both its conveying and fluidizing response.
acceleration and deceleration: A just-fed particle is
_
swatted or impacted and given the speed of the rotor or
accelerated. Upon striking a rib on the case liner, it slows
down and glances away as a decelorated particle. Because
it is moving more slowly than the rotor, it is swatted from
the rear (which action crumples that part of it) and re-
accelerated. This action is repeated at high frequency in
a spherizer.
unsup~orted trajectory: Is herein used to insure that the
explanation of the action of processing particles in a
machine with stationary ~or possibly counter-rotating) ribs
and rotary blades is not confused with usual grinding,
smearing or shearing action. By keeping the rotor m~mbers
well-spaced from the stationary members, a bouncing and
swatting sequence exists. The use of closely adjusted
rotor members would defeat the desired action and cause
clust by grinding. If the particles were unable to bounce
and glance off rotor ancl stator, there would be little or
no ~ormation of spheroids. An overloaded machine blade
just pushes a mass of feed material ahead of it and gives
a grinding action not unlike that of a ball mill ancl pro-
duces dust. The use of an air path or unsupported trajec-
tory is necessary for the desired hammering action which
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results from impacting or swatting the particles against
one target surface at a time to cause spheroid formation.
single surface mlpaction is not a beating or har~meriny on
an anvil which would compact the inner structure of the
spheroid.
blade: The replaceable hard alloy moving impact surface
fitted to the tip of each paddle of the rotor - usually
four to sixteen per rotor varying with diameter of rotor.
sweep air: Air or other gaseous transport fluid (as
"burned air" or other controlled atmospheric) used to convey
the particulate material through or from the spherizer
and to a cyclone or other collection device~
residence time: Time contained in processor.
tar~et surface: Case liner or rib on liner against which an
accelerated particle impinges or impacts.
carrier fluid: Medium, usually air, in which particles are
conveyed. May be any gas, gas mixture, or in special cases
a liquid.
B~IEF DESCRIPTION OF THE DRAT~INGS
-
Figure 1 is a diagrammatic sectional view of a portion
of the apparatus according to the present invention showing
the manner in which the feed material undergoes spherizing;
Figure 2 is an elevational view of the apparatus with
portions thereof broken away to illustrate the details of
construction;
Figure 3 is a sectional view taken along line 3-3 of
Figure 2 and viewed in the direction of the arrows;
Figure 4 is a fragmentary view of the sectional liner
plates as viewed from inside the case to the right of the
door opening;
Figure 5 is a fragmentary view of the sectional liner
plat:es as viewed from the inside looking left;
Figure 6 is a view similar to Fiqure 5 with the liners
removed; and
Figure 7 is a diagrammatic representation of the
apparatus and method of the present invention.
DET~ILED DESCRIPTION
A preferred form of apparatus is illustrated in
E'i~ures 2 and_ . This spherizing apparatus or "shot mill"
consists of a case assembly provided with a feefl assembly,
a rotor assembly and drive means. The feed assembl~ (4)
consists of a rotary feeder (5) which controls feed rate
as well as prevents massive air inflow. The feed hopper
(10) may be equipped with baffles to prevent particles
from being thrown back by the rotor and is fitted with an
air intake nozzle (12) which contains an air flow control
damper (13). The hopper (lO) is mounted on the door (6)
which is equipped with hinges (8) and lock tabs (7) and
held by lock bolts (9).
The case assembly consists of an outer shell (14),
back plate (15), supports (19), baseplate (20), inner
structural ribs (16) which also form temperature control
cooling air ducts (see Figure 6) which supply air intro-
duced at inlet nozzle (17) for conveying the processed
material when that air flow joins the inner air flow
admitted at (12) and egresses through the product discharge
port (18). A clean~out port (21) is provided under the
grating to assist in removing the grating and removing for-
eign metal when a grade change is being made.
The case assembly is fikted with a removable liner
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support shell (24) and a wear resisting liner (25). This
liner is fitted with ribs (3) as in Figures 1, 2, 3, 4 & 5,
either by casting or by welding application. The liner may
be a heavy rolled sheet or may be an assembly of sections
which may be chill cast. Figures 2 and 3 illustrate two
sectional rings formed into a liner. The shell (24) and
liner (25) are fitted with outlet ports and yrating (26)
(also see section Figure 4, 5, 6~
The rotor assembly consists o~ a hub (27) which
carries feed acceleration fan blades (28) and support discs
(29) having air recirculation holes (30) suitably disposed.
The discs (29) carry blade support plates (31) which in
turn carry wear resisting impacting blades (32) which are
the equivalent of the schematic moving impact plate (2) of
_igure 1.
The rotor assembly is carried by drive shaft (33)
supported by rnain bearing (34) and optionally by an out-
board removable bearing (35) indicated for larger machines,
and shown only in the schematic drawing Figure 7.
Drive coupling (36) connects with drive motor (37)
which is controlled by console (38). Also see Figure 7.
In Figure 7, the produot discharged from (18) is
ducted to blower equipped cyclone (39) which discharges
pressured aix to case secondary air inlet (17) and air inlet
nozzle (12) with excess air discharged to vent. Cyclone
(39) drops the spherized metal mix into sizing screen (40)
which supplies gravity tables (57-59) with material for
separation using equipment standard to known art.
Figure 1 shows liner plates (25) with ribs 3, 3b, 3c,
~ 3d consisting of either hardface welcled ridges, weld
attached matrices containing granular carbides or other
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abrasion resistant ridges having crossectional shapes
generally approximating the forms of either, 3b, 3c, or
3d, however attached.
Figure 4 shows the sectional liner plates as viewed
from inside the case to the right of the door opening and
shows target ridges (3) which are generally parallel to
the axes of the case in the forward liner while the rear
liner exhibits angled ridges whose angles serve to aid
in moving the circulating material toward the rear where
the exit grating is located. The short reverse angled
targer ribs (3) assist in minimizing abrasive wear of the
edge of that liner which a~uts the rear wall (15) (not
shown). The angles of these angled ridges are exaggeratPd
but show that effective target deflecting is possible even
with non-axial ridges.
Figure 5 is similar to Figure 4 except viewed from
inside looking left at 6:00 to 7:00 to show the exit grating
(26) as well as straight and angles ribs (3). Figure 6
shows the same view as Figure ~ but with both the liner
(25) and liner support (24) removed to show the crossover
section of the reinforcing rings (16) which form the ducts
for cooling and product removal sweep air which joins the
air carrying the processed materi.al through the grating
(26) and conYey the product (1) out (18~ and to the
cyclone (39) (see Figure 7).
Example I
Radiators consisting of mixed fins and tubing of
aluminum and copper are reduced to small fragments by ~nown
means such as "alligator" shears, ~'Cumberland" ~or other)
granulators and the like. The resultant mixed metal leaf-
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~7~)~7
lets are separated from the non-metallic carrier material
and fed to a spherizer as herein above describ~d. This
machine processes the feed material as below described.
The rotary feeder (5) Figures 2 and 3 drops the feed
material (1) into hopper (10) where controlled air flow
entering (12) sweeps it into the machine. Its residence
time in the machine is controlled by air clamper (13). As
the fra~nents are bounced back and orth between blades
(32) and the ribs (3) on the liner (25), -they become gen-
erally spherical in shape and in such denser form exit
through grid (26). An intense air eddy condition exists
within the impacting area in the mill which effect is aided
by the fan like action of the wide blade support plates
(31) and the holes (30) which interconnect the chambers
formed by the rotor discs (29).
Upon dropping or being mildly blown through the grid
(26), the dense spheres need more air flow to transport
them up to a cyclonic separator. Such secondary air is
provided by air entering inlet (17) where it exits through
outlet (18), mixed with sweep air which entered through
(12). If an excess of sweep air were passed through the
inside of the case, it could reduce resiclence time to give
insufficient or incomplete spharizing.
r~he conveyed product is separated from its conveying
air by cyclone (39) and dropped into a Sweco sizing screen
(40) shown in Figure 7. Each discharge port supplies a
gravity table final separation device. After separation,
the dense spherized produce is suitably packaged for sale
or other conversion.
30 , Copper separations may easily be obtained with less
than 3~ maximum aluminum content and, under close super-
~87
vision, copper purity of 9~/99~ may be obtained~
~ le II
A mixed feed material composed of electronic waste
rnaterial such as olcl radios, telephone switchboard and
relay station equipment and the li]ce i5 pulverize~ and
granulated into a mixture of particles containing non-metal
such as plastic, glass, porcelain and carbon mixed with
particulate and thin sheet metallic particles from ''printed
circuitry" containing iron, bronze, silver contacts, alum-
inum sheet chasis and/or condenser foil, plus copper wire
and copper foil, as well as a fair amount of soldered wire
ends and soldered terminals of copper or brass.
This feed mix after size reduction is freed of its
non-metallic content on gravity tables, the iron is removed
by means of magnetic belts and the remaining mixture of
metals run through a room temperature spherizer to avoid
losing the solder.
The spherized mix is graded into sizes and each size
subdivided by gravity tables using the well-known fluid-
ized bed and conveying vibration screen method. Spherized
pellets of leaded copper, copper and bronze may be separ-
ated from less dense spheroids of brass, hard bronze, and
aluminum. Subse~uent passes over more closely adjusted
gravity screens can separate these fractions. Even copper
coated aluminum wire can be separated from copper wire
and aluminum wire. Silver contacts and soldered terminals
may be separated from 'che copper fraction in closely ad-
justed fractionating of spheroids using specific gravity
tables due to the fact that the malleabilities and work
hardening properties differ.
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Example III
In T~xample III, fragmented scrap brass tubing and
she!et is separated from an antimony-bismtlth-lead alloy used
in bending brass tubing in the manufacture of wind instruments.
~hile this separation can be accomplished by other simpler
means, it serves as an example of separating ductile brass
from a non-ductile metal which under high speed impaction
is converted to dust and thus separated in a cyclonic
separator followed by a bag collector for the metal dust.
Example IV
When a spherizer is fed shredded, particulate, hard
bronze spring metal and operated at high surface velocity
and temperature, the particles reach or approach "red heat'
and become annealed enough to become malleable and form-
able into spheroids. rThe change in physical form renders
the material more easily handleable and enhances its market
value. Separation follows the same general steps as in
Example I.
Example V
i-Ieavily lacquered aluminum containers and enameled
aluminum magnet wire often are problems to recover. Ma-
terial to be reclaimed is precut to feedable size and
spherized at a temperature hot enough to burn off the in-
sulation and lacquers. The lacquer pigment is freed from
the metal in the spherizer, burnished and separated in
suitable dust collectors without need for the usual grind-
ing and polishing with a carrier medium as in a series of
yranulators. Wire which was unrecoverable by conventional
means has been spheriæed and reclaimed in upgraded form.
Used toothpaste tubes and aluminum cans also may be re-
covered without "burning off 1l in a furnace and baling.
15-
~117(~37
]~xam~le VI
A particulate mixture of cured therrnosetting plastic
such as phenolic molded parts mixed with a particulate
the!rmoplastic material of similar specific gravity such
as granulated polyvinyl chloride is obtained by grinding
up plastic waste.
When this mix is fed through a spherizer at a temper-
ature just adequate to render the PVC deformable but not
tacky, it forms beads while the hard thermoset particles
are milled to dust if given adequate residence time. The
warm rubbery PVC is easily separated from the th~rmoset
dust - in suitable cyclones or on simple sizing screens.
This separation is made possible by using the
malleability of the thermoplastic material at the specific
or selected temperature where malleability is acquired
and is characteristic of each given material. Similarly,
heated polystyrene or mathacrylic can be separated from
brittle thermoset materials or, if cold and brittle them-
selves, may be shattered to dust and separated from ductile
or tough materials at room temperature such as certain
nylons, polyolefins or polycarbonates.
While the general type of apparatus is typically
presented in Fi~ures 2, 3 & 7, it must be understood that
any mechanism which employs a moving surface and a station-
ary surface in a non-contacting relationship - separated
by at least the maximum dimension o~ a particulate feed
material (preferably by a greater separation equal to from
2 to 10 times the particulate feed materials maximum dimen-
sion) where the difference in surface speeds of the two
~ surfaces is over 5,000 SFM (and where means for feeding,
~1~137
containing, and withdrawing the product are provi~ed) comes
wit:hin the scope of the herein taught art.
The particular mechanism descrihed is described
as running in a continuous rather than as a batch treatrnent.
It is obvious that the machine can dischar~e into a stor-
age container and recycle the same batch of material repeat-
edly until a desired degree of treatment is obtained and
thus constitute a "batch" process. Therefore the process
is capable of either batch or continuous poeration al-
though a continuous operation is usually preferable.
~ither arrangement is considered as taught by this subject
process.
The process carried out by the described apparatus
consists in projecting and impacting a feed material or
mixed feed containing at least one malleable component to
form it into spheroid shape. Said generally spherical
shaped particle is uniform and easily separable from a mix-
ture of non-malleable particles.
It is especially effective to orm all contained feed
material into spheroids because, if spherized to each
material's ultimate or true density, spherical shapes com-
posed of di~ferent materials are easily and precisely
separated on efficient "gravity tables".
rrhe spherizing process, however, opens a new concept:
the use o~ the fact that no two metals work harden to ex-
actly the same degree at the same temperatuxe (unless the
temperature is above the annealin~ temperature of both
metals) and consequently don't compact equally to their
ultimate density. Differences in the resulting ~pparent
Density or ASO determine the ease of separation on gravity
-17-
~n~
tables. It just so happens that in general the heaviest
metals are intrinsically more malleable than the lighter
ancl work harden less. Therefore aluminum, for example,
in addition to being intrinsically lighter, forms even
S lighter spheroids with lower apparent specific gravity.
This makes its separation from copper even easier than it
would be if dense aluminum spheres of true specific
gravity resulted - as melted shot.
Because of the uniqueness of the process and of the
purity of the products obtainable, this process consti-
tutes a valuahle addition to the art of metals separation
and recovery.
Because either annealed or work hardened metal shot
can be produced by control of speed, residence time, and
temperature, the product itself is new, unique and useful.
It is easily identified by its surface texture, even in
its porous or low speciic gravity, spherical, work hardened
form, it is easily poured and fed into shape forming cold
pressing dies or remelting furnaces.
In its annealed form with higher or even ultimate
density (if melted or hot forged in the spherizer), the
particles are easily identified under the microscope by
their impacted surfaces. These denser, annealed spheres
comprise a new and useful raw material suited to auto-
matic shape-making operations as well as for remelting.
Although this process has been in commercial oper-
ation for a few months, there has been insufficient time
to establish critical speeds and all termperature effects.
A simple primitive test with a modified fan-like device
established that the method was workable. Bigger units
were immediatel~ put to work at higher and higher surface
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87
speeds. Representative speeds employecl and found e~f~ctive
are 10,000/15,000 surface feet per minute, although slower
speeds ~e.g. 5,000 SF~l) rnay be adequate for certain separ-
ations. Also to be mentioned is the observation that
when the "blades" (32) are fitted with less than 1/4"
clearance from the liner ribs (3), a dust forminy problem
arises. Preferred blade clearances appear to he from 5/8`'
to 1 1/4" when processing feed material passing 1/2" to
1" screens in the granulators although a detailed study is
yet to he made. It is interesting to note that the patent
literature is full of described equipment having close
blade clearance and used to make metallic dusts, but none
mention use of wide separation of blade-to-rib to make
shot-like spheroids. Meither is mention made of the use of
elevated temperatures.
One limitation of the process should be kept in mind;
very soft metals like tin-lead solders tend to plate or
burnish onto other metals if severely impacted, especially
at elevated temperatures.
Also bear in mind that brittle metals such as certain
zinc alloys, "type metal" alloys containing antimony, and
alloys of bismuth, silicon and the like, may break into
dust and may thus be separated and collected as dust from
mixtures of spheroided malleable metals such as aluminum
and/or copper. The final dust collection equipment is
known art for other industries, but the process for im-
pacting the malleable fraction in a device of the described
type to make dense spheroids which separate from metal
dusts is new art. Use of the described imparting device
to selectively make dusts of those particlers having a
given degree of friability is also new art. It does not
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7087
just grind everything in the mixture to dust as do usual
machines having no control of grinding intensity.
It should ~e pointed out speciically that the pro-
cess consists in the swatting and bouncinq of ductile
material fragments instead of cutting same. The impacting
surfaces (2) or "blades" (32) are made of hard alloy not
because they must cut, as in a granulator, but because
they must resist a special type of high speed wear which
is perhaps enhanced by the presence of metal oxide films
on the metals being processed. In any event a mild steel
blade (32) will not last many hours even when processing
shredded copper foil from which its printed circuit boards
has already been removed in earlier granulation and separ-
ation steps.
It is considered quite probable that the disinte-
gration equipment used in the well known equipment for
'tmicronizing" of friable powders using compressed air to
accelerate and convey particulate material to and against
a targets would, if tested with malleable materials
likewise form spheroidal products. Such systems, however,
would probably be economically non-competitive with the
present invention when used with the heavier, larger,
bulkier, and irregular types of metallic feecl materials
encountered with metals reclamation.
It is expected that the combination of the ability
to spherize malleable metals by means of this process; -
which also has the ability to shatter brittle metals
and even, if specifically designed for the purpose, form
particulate granules of lathe turnin~s composed of steel,
gray iron and the li~e - with its shattering action on
brittle materials, may well lead to broad usage for sal-
-20-
1117(~7
vaginq much of the small part mixed Metal waste not pre-
sently reused.
.~ new line of products consistlng of controllable
specific gravity spheroids of assorted metals is presented.
The process for making same is described and an apparatus
for accomplishing the process are given in detailed draw-
ings. These are additions to the art of metals separa-
tions and recovery but also contribute new products
which are raw materials capable of being used for other
new products.
