Note: Descriptions are shown in the official language in which they were submitted.
10~4~5~
,
sackground of the Invention
This invention relates to methods and apparatus for crush-
ing various materials. The invention is especially useful for
reducing ore, rock, stone, coal, and the like. In mining or
extraction, random size pieces of mineral material are produced,
some too large to be carried out of the mine or quarry on con-
veyor belts of practical and economical width. Bucket or skiff
conveyors have been tried, but have been expensive to build,
operate and maintain. Thus, motor trucks have been used to
carry uncrushed minerals from the bottom of mines or quarries
to a distant or upper surface for crushing.
For various reasons, including perhaps the desire to provide ~ -
reversible hammer rotation and design symmetry, the massive
crushers most commonly used heretofore in the crushing of large
chunks of heavy minerals have included a top inlet and bottom ~-
outlet. Positioning a conveyor belt below such a crusher to
receive crushed material from the outlet involves elevating the
crusher above ground on heavy supporting framework, or construct-
ing a trench beneath it. This can raise the inlet to a difficult ~-
or prohibitive height for conventional mobile loaders or loading
equipment, and/or makes the crusher considerably less mobile
or less stable and more expensive to install.
In principle, mineral extraction costs can be reduced by
crushing the large chunks to a convenient size in the quarry
or at the mine face, and then carrying them to the surface by
belt conveyors of practical size and width. However, under
many circumstances, the above-described problems and the size
and expense of available mobile crushers frustrate the use of
this money-saving procedure.
- 2 -
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1~i44Si `
Objects of the Invention
-
It is a primary object of the present invention to provide
a relatively simple and inexpensive crusher which makes it
unnecessary to truck mineral materials from the bottom of a
mine or quarry.
Another object of the invention is to provide a crusher
machine which effectively performs the necessary functions of
far heavier and more expensive mobile crushers heretofore used.
Still another object is to provide crushing apparatus which
can be conveniently operated in a mine or quarry and which may
be used to crush moisture laden materials while reducing or
eliminating clogging.
Yet another object is to provide a crusher which can be
discharged directly to a conveyor, screen, or other transport and
processing equipment and yet requires no high elevating framework
or subjacent trench.
A further object is to provide crushing means which can be
loaded directly by mobile loaders such as front-end or over-
the-head loaders.
Another object is to provide crushing apparatus which can
itself be readily constructed in a mobile form which is relatively
stable against tipping, is relatively simple and light in weight,
and yet provides a convenient discharge.
Another object is the provision of crusher machines having
the aforesaid features which may be used to advantage in the
crushing of coal, ores and other materials, but particularly
in the crushing of coal or limestone.
Yet another object is to provide a method of impact crush-
ing mineral materials which can significantly reduce problems
; heretofore associated with the transport of mineral materials
- 30 from the floor or face of a mine or quarry.
Upon consideration of the summary and the various embodi-
ments of the invention described below, it will be apparent
.
~ 44Sl - ~
,nat the invention can be embodied in forms which atain some or
all of the above objects. Moreover, additional objects will
occur to those skilled in the art. In any event, the practice
of the present invention offers various significant advantages,
Summarv of the Invention
.. _ .
The disclosed apparatus provides material reduction appara-
tus for mineral materials such as ore, rock, stone, oil shale,
coal, lignite and the like. Such apparatus comprises a rotor
having any suitable form of impact members mounted thereon,
for instance, fixed or pivotable hammers or bars. These are
arranged in spaced relationship about the rotor, and their
peripheries define an impactor circle, of which there may be
several.
The rotor is mounted for rotation in a housing having a
curved, imperforate impact surface. "Imperforate" means that the
surface is regular or irregular, but is for the most part
free of "through" holes; for instance, if the surface is in the
form of a plate punched with holes, this plate will normally
be backed up by a blind plate which closes off all or most of
the holes. On the other hand, the impact surface may be provided
by filling the bottom of an enlarged housing with crushed
mineral material, such as the material which is crushed in said
apparatus, until the level of said crushed material reaches
a level slightly below but adjacent to said impactor circle.
The aforesaid impact surface defines the outer perimeter
of a reaction zone subtending an arc in said impactor circle
- which may include the lowest point in said impactor circle and
extend upwardly on either side of said point. Within this
zone, the rotor impact members, the material to be crushed
and the impact surface interact to crush the material.
10644Sl
,
In the case of a rotor having several circles of impact members,
there may be several of such zones in which the zones themselves
and/or the hammer circles may have different diameters or be
physically separated from one another by members intermeshing
with laterally adjacent impact members, Generally, the impact
surface or surfaces are free of discontinuous components inter-
meshing with (or in the lateral space between) laterally adjacent
pairs of impact members. "Discontinuous components" refers to
; a durable member or members providing a series of inward pro-
jections from the impact surface or teeth spaced peripherally
about the impact surface and separated by gaps sufficiently
large to momentarily catch, stop or reverse the direction of a
significant proportion of the mineral material which enters
the gaps and collides with the projections.
The apparatus includes an inlet duct for charging the
material to the rotor housing. The inlet duct may open into the
housing directly adjacent the reaction zone or at any other
suitable location. For instance, the duct may open into the
housing within the impactor circle or alongside it. Preferably,
- 20 the inlet is open to the atmosphere, so that air may be drawn
or forced into the housing as the feed material enters, and the
air and feed may be caused to follow a common path through the
apparatus until after they have both entered a discharge chute
or duct. Also, the inlet may be connected with or include,
any suitable means for controlled feeding of material into
the housing in a predetermined range of mass rate, e.g., as by
using an input conveyor means, including without limitation
vibrating pan feeders (which are preferred), apron conveyors,
., .
table feeders and (where the feed material is in relatively
small pieces) a belt conveyor,
~ 5 ~
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``` 10~4451
The invention includes a discharge chute which at least
partially encloses a reduced material departure path. The path
includes a lower surface which extends longitudinally away from
the rotor and into the material departure path to an extent
; sufficient to cause scouring of the lower surface by the
discharged material, while preserving the major portion of the
kinetic energy originally imparted to the material by the rotor,
whereby clogging of the chute by the material is reduced or `
eliminated. In certain embodiments of the invention, the material
10 departure path is generally elevated above a line tangent to `
the impact surface drawn from the downstream end of the reaction
zone. In one embodiment, the lower surface of this chute is of
flat, curved or involute form extending from the downstream end -
of the reaction zone at an angle above the tangent line just
~; discussed. This orientation of the lower surface is important
since it minimizes or eliminates the accumulation of fine parti-
cles or moist material at the lower end of the chute due to the
scouring effect of heavier particles skimming along the elevated
lower surface as they travel up the chute. The angled lower
- 20 surface changes the direction of movement of material pieces
and tends to absorb an initial and preferably minor portion of
their energy; nonetheless, the discharge chute may be provided
in addition with a direction changing and energy absorbing means
which deflects the reduced material toward an adjacent conveyor
or handling station, at the upstream end of the chute.
The additional direction changing and energy absorbing means
may be of any type, including a rock box, chain curtain, angled
metal surface or the like. It is connected with or placed
beyond the discharge chute operationally, if not physically,
3~ and is oriented in the material departure path in position for
- 6 -
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~; . . ~ , , - , :.
. . ; ` ! ` . , ` '
,. : ':: '' ` '
-` ~.o6445~
receiving all -- or at least the larger -- pieces thrown off
by the rotor, for slowing such material by absorbing an add-
itional and preferably major portion of the remaining kinetic
energy thereof, and for discharging such material from the chute
without recycling to the rotor. Such means may discharge the
material which reaches it by causing it to descend either dir-
ectly or through any suitable discharge means, preferably unob-
structed, including a further chute to any suitable receiver.
This may for instance be a vehicle, a conveyor, a screen, the
inlet of an additional material reduction apparatus, or another
transport or processing apparatus. In a preferred embodiment,
the discharge chute and its angled direction changing and energy
absorbing lower surface are arranged to convey the entire range
of materials thrown off by the rotor to the additional direction
changing and energy absorbing means, and from thence to a dis-
charge outlet without separation of the pieces of differing
particle size and without significant return of material from
either direction changing and energy absorbing means to the rotor.
,,
This discharge outlet is more preferably at least partly and pre-
ferably completely at an elevation which is higher than the low
point of the impactor circle and most preferably higher than the
axis of the rotation of the rotor.
Also, it should be apparent that when ready for use, the
apparatus will be provided with means for rotating the rotor
with the periphery of the rotor adjacent the impact surface ;
moving in the direction of said outlet channel and with suf-
ficient speed to throw reduced material up the discharge chute
to the additional energy absorbing and direction changing means.
In accordance with the method aspects of the present
invention, air and mineral feed are introduced into a housing
- 7 -
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:
`- ~0644Sl
rough an inlet opened to the atmosphere. The air and mate-
rial feed are caused to flow along a common path from said
inlet to a rotor in said housing. The feed material is contacted
- with rotating impact members on said rotor and with an impact
surface in a reaction zone subtending an arc in said impactor
circle which may include the lowest point in the circle desc-
ribed by the rotating impact members at their peripheries and
extend upwardly on either side of said point. Material crushed
; by said rotor and impact surface is thrown upwardly and outwardly
from the rotor along an at least partially confined discharge
chute located above a tangent from the impact surface drawn from
the downstream end of the reaction zone. Using the kinetic en-
ergy imparted thereto by said rotor, the crushed material is
thrown to a level above the axis of rotation of the rotor. While
the crushed material is still in flight, at least some of the
pieces of crushed material are impinged against an angled lower
surface of the discharge chute to scour that surface of agglo-
merated particles and then passed on upwardly to an additional
energy absorbing and direction changing means. Then the crushed
- 20 material is caused to descend from the additional energy absorb-
ing and direction changing means and to discharge from the
. .
apparatus without further contact with said rotor.
With the aid of the drawings described below, a few
illustrative embodiments of the apparatus and the method of the
present invention will now be described. A person skilled in -
the art will readily recognize that other embodiments are
possible, and that the invention is not limited to the embodi-
ments shown.
Brief Description of the Drawings
FIG. 1 is a side elevational view, partly in section, of
a crushing machine embodying this invention.
-- 8 --
` 10~4Sl
FIG. 2 is a schematic illustration of an alternate form
of crushing machine according to the present invention.
FIG. 3 is a sectional view of a preferred embodiment of
the crushing machine of the present invention.
FIG. 4 is a schematic illustration of still another form
of crushing machine embodying the invention.
FIGS 5A to 5E each show a fragmentary sectional view
of the lower wall of the discharge chute of the present in-
vention, illustrating alternative shapes therefor.
Detailed Description of Various Embodiments
There follows a detailed description of preferred embodi-
ments of the inven~ion, reference being had to the accompanying
drawings, in which like reference numerals generally indicate
like elements of structure in each of the several FIGURES.
A crusher 10 embodying the invention is shown schemati-
cally in FIG. 1. The crusher has a housing 12 with rotor
shaft 14 mounted for rotation therein, in suitable bearings
(not shown), A plurality of rotor discs 16 may be spaced axially
~ . .
on the rotor shaft 14, each carrying four hammer shafts 18,
mounted at 90 intervals near the peripheries of the rotor discs
16. The discs 16 serve as pivotal mountings for four sets of :
impact members, e.g., hammers 20, including four hammers in each
set which are laterally (or axially) spaced relative to each
other. The hammers could be mounted at random spacings about
the discs, as long as weight balance about the rotor shaft is
maintained. On rotation of ~he rotor shaft 14, rotor discs 16
and hammer shafts 18, the outer peripheries of the hammers 20
define an impactor or hammer circle 22.
The housing 12 includes a curved, imperforate impact sur-
face or member 24. Surface 24 defines the periphery of a
reaction zone subtending an arc alpha (a) in said impactor
circle which may include the lowest point P in impactor circle 22
_ g -
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~oti~45~ :
and extend upwardly on either side thereof. Within this zone,
the impact members, the material to be crushed and the impact
surface interact to crush the materlal.
While it is preferred that the impact surfàce be a fabri-
- cated member, preferably of highly wear resistant metal, the
impact surface may be fabricated of other materials. For
instance, it is contemplated that all or part of the fabricated
impact surface 24 might be omitted, leaving the lower portion
of the volume of housing 12 unoccupied. Upon the feeding of
mineral material to the crusher machine, this open volume would
become packed with crusned feed material, the level of which
would rise in the housing to a level controlled by the rota-
tion of the impact members and by the passage of additional feed
material, and would thereby be formed into a curved impact
surface.
The apparatus includes a discharge chute or duct 26 which
at least partially encloses a reduced material departure path
generally corresponding to the trajectory imparted to the
material at the downstream end of the inter-reaction zone and
generally indicated by arrows D This channel may be a duct
of tubular or other shape enclosed partially or completely
throughout its length and circumference. It will however be
sufficiently enclosed to confine or at least partially confine
the reduced material proceeding along departure path D The
surfaces of this duct 26 may be fabricated of metal, as shown,
or may be provided with rock facings, e.g. rock boxes. In
the preferred embodiment, the duct 26 has a lower surface or
confining member 28 which has an upwardly sloping or curving
surface extending from the downstream end of the impact sur-
face 24 along a path elevated above a line T tangent to the endof the essentially circular im~act surface 24, as shown. Mat-
-- 10 --
1t)~44Sl
erial exiting from the crusher will initially follow a tra-
jectory which is parallel and closely adjacent to tangent line
T, thus the upwardly `sloping or curving surface of member 28
lying above tangent T will be constantly struck and scoured
by crushed material as it moves up discharge chute 26, thereby
changing the direction of and absorbing some energy from the
crushed material as it moves.
The surface of member 28 may also be coincident with
tangent T to minimize impact by the passing crushed material;
however, in this instance it has been found that fine particles
in the moving crushed material tend to pile up at the lower end
of member 28, especially when the material being crushed is
somewhat moist. This piling up of moist, fine particles can
cause clogging of the discharge chute, necessitating shutdown
time for cleaning. To reduce or eliminate such clogging, an
upwardly sloping or curving surface on member 28 is preferred,
as discussed in greater detail with regard to FIG. 5. To permit
adjustment in the amount of scouring received by the surface of
member 28 and the extent that the direction and energy of the
crushed material are altered, a hinge 29 may be provided to
permit adjustment of the angle B between tangent line T and
member 28, using appropriate adjustment means 30, such as a
screw jack or similar device. Also, in the preferred embodiment,
the upper surface 31 terminates in an additional direction changing
and energy absorbing means 32, e.g. a rock box, chain curtain or
fabricated metal impact surface, oriented in the material
; departure path D and positioned for slowing the material by
absorbing a major portion of the kinetic energy thereof.
In this preferred embodiment, the energy absorbing and
direction changing means 32 delivers all of the material received
from the rotor means to a discharge outlet 34. The discharge
10~;~4Sl
~ tlet 34 is preferably entirely open or unobstructed, so that
the entire quantity of reduced material which strikes the energy
absorbing and direction changing means may descend therefrom to
any suitable receiver. When the discharge outlet is at least
-~ partly, or preferably completely, at an elevation which is higher
than the low point P of impactor circle 22, and, most preferably,
higher than the axis of rotation of the rotor shaft 14, the
output of crushed material from discharge outlet 34 may readily
be fed directly onto a conveyor 36 without placing the conveyor
in a trench under the crushing apparatus and/or without elevating
the crushing apparatus on a high framework with the conveyor
running underneath. This also makes it possible to mount the
crusher on simple transport means, such as skids 38, crawler
tracks, walking mechanism, wheels or the like so that it may
be moved to any desired location in a mine, quarry or other
facilities.
Certain advantages may accrue from properly engaging the
base, e.g. skids 38, of the crusher with the ground surface,
e,g. the bottom of a mine or quarry. This can be done for
instance by interposing between the base and the ground surface
a resilient sheet member which is free of attachment with the
ground and which may be a durable porous synthetic and/or
natural elastomer or blend thereof. The sheet will have a
substantial thickness and resilience properties such that its ~ -
upper and lower surfaces will deflect horizontally relative to
; one another in response to horizontal vibrations of the machine, ;~
; while retaining frictional engagement with the machine and ground.
The sheet may also undergo localized vertical deflection to
accommodate irregularities in the ground surface. Thus, the
sheet temporarily secures the machine at the desired location
on the ground, permitting ready removal and at least partially
- 12 -
~0~44S~
reducing any tendency of the machine to creep. The machine may
also be secured by a tether, if desired.
In view of the intended manner of operation of the appara-
tus, those skilled in the art will readily recognize from the
foregoing description that the apparatus, when ready for
use, will be provided with a means, such as electric motor 40
and drive belts 42, for rotating the rotor 14 with the peri-
phery of the rotor adjacent the impact surface 24 moving in the
direction of discharge chute 26 and with sufficient speed to
throw reduced material up discharge chute 26 to the energy absor-
bing and direction changing means 32, Infeed conveyor 41 may be
used to deliver material to be crushed to inlet opening 43.
In FIG. 2, the uncrushed ore or other material is delivered
through a feed-in chute 44 into the axial center of a cage mill
46 which includes a pair of spaced-apart discs 48 which support
; therebetween a plurality of rods or bars S0 which crush the ore
material and throw it upwardly into the discharge chute 52 and
out the nozzle 54. Discharge chute 52 includes a lower confining
member 56 which has an upwardly sloping or curving surface
extending from the downstream end of impact surface 58 of cage
mill 46, along a path elevated above a line T' tangent to
the impact surface in a manner identical in principle to
that discussed regarding the embodiment of FIG. l. Though not
illustrated, member 56 may also be hinged, if desired.
The presently preferred configuration of the apparatus
shown in FIG. 3 has a housing 66 with rotor shaft 68 mounted
for rotation in suitable bearings (not shown). Axially spaced
rotor discs 70, carrying three hammer shafts 72, are mounted -~
on shaft 68 for rotation therewith. The hammer shafts 72,
mounted at 120 intervals near the peripheries of axially spaced
- 13 -
. ~ . , .
10644Sl
rotor discs 70, serve as pivotal mountings for three axial
rows of hammers, each row comprising one double width, two-
shank hammer in the middle and a single width, one-shank hammer
hammer arrangement at each end, as shown in Figure 12 of our
Canadian Patent No, 1,005,038 issued February 8, 1977. The housing
66 includes side panels 76, the feed ramp 78, curved imper-
forate impact member 80, inlet chute 81 and discharge chute 82,
along with various other auxiliary equipment.
Inlet chute 81 is of the same width as the portion of the -
housing in which the hammers rotate, and it is defined by side
walls 84, by downwardly and outwardly inclined end wall 86 and
by downwardly and inclined end wall 88, as well as end wall
supporting structures 90 and 92 which can be bolted to the
.
housing at points 94 and 96 respectively. In the configuration
shown, the inlet chute exhibits some tendency to urge incoming
material from right to left generally in the direction of
motion of the periphery of the downrunning rotor 68. However,
the inlet chute end support members are so shaped that the chute
can be unbolted and the positions of the ends reversed, so that
20 the chute will then have a tendency to urge incoming material ~
~; from left to right, generally in opposition to the direction -
of rotation of the hammers.
Upon entering the housing, incoming material may first
encounter the hammers 74, or the housing side walls 76, or the
feed ramp 78. This feed ramp has a replaceable wearing surface
98, held in place on a pivotally mounted platen 100 by mounting
bolts 102. The platen pivot 104 is a horizontal bar extending
between side walls 76 near the upper portion of the housing,
- spaced radially from the impactor circle The lower end of the
feed camp is fitted with adjustable securing means 106, securing
the lower end of platen 100 either closely adjacent to the
- 14 -
10~;44Sl
.
impactor circle or at a plurality of positions at furtherradial spacings therefrom. For protection of the machine, the
bar 106 may be of only limited strength so that it will break,
allowing the feed ramp to swing down and "unload" the rotor,
if the rotor encounters a large object that will not shatter,
thus possibly averting self-deskruction of the machine.
Imperforate impact member 80 also includes a plurality of
replaceable wear surfaces 110, the first of which, 112, has
corrugations formed therein. These wear surfaces are held in
; 10 place on a curved base 114 by suitable mounting bolts 116. ~-~
Impactor member 80 is also pivotally mounted on a fixed pivot 118.
; The cross bar 120 at the right or downstream side of the impact
surface 80 can be secured to any suitable adjusting means, not
shown, by means of which the right end of the base and associated
; wear surfaces can be moved radially closer or further from the
impactor circle.
The discharge chute 82 has a lower or confining member 122
which comprises an upwardly sloping or curving surface extending
from the right or downstream end of impact surface 80, along
a path elevated above a line T" tangent to terminal lip 124
of impact surface 80. Lower surface 122, upper surface 126 and
side panels 128 define a chute having a completely closed
circumference. The orientation of the chute generally corresponds
to the tra]ectory imparted to the material at the downstream end
of the inter-reaction zone. As prevlously discussed, the angle
of member 122 may be adjustable, if desired. The additional
direction changing and energy absorbing means has been omitted
from this view to permit showing the other parts of the appara-
tus on the largest scale possible, but it is understood that
such means will be generally similar to that shown in the
. .
.: ' , ' . ', , ' : . ' ~ ' . '
0644Sl :
other figures and to that described above.
The following is a summary of parameters of à purely
illustrative machine similar to that shown in FIG. 3, designed
for crushiny cement rock. It uses a rotor having a hammer
circle of sixty inches, which clears the impact surface by about
1/2 to 3 inches or more. The hammers are approximately 18
inches long and have a front face to back face width of about
9 inches. The single and double shank hammers have side to
side widths of 12 and 24 inches respectively and weigh about
320 and 700 pounds, respectively. The entire rotating mass inclu-
ding hammers, rotor discs, shafts, flywheel and sheaves is
about 20,000 pounds, and the machine as a whole weighs less
than 100,000 pounds. It appears capable of doing the work of
previously known mobile crushers weighing several times as much.
The rotor is designed to turn at about 480 to 700 RPM.
The presence of some heavier multi-shank hammers on the rotor
makes it possible to get equivalent or better crushing perfor-
mance at lower rotor speed and therefore lower levels of machine
vibration amplitude and creep, as compared to a larger number
of single shank hammers of the same total mass, rotating faster.
Thus, it could for instance be possible to provide the machine
with hammers which extended the full available width of the -
; housing and had three or more shanks.
Uncrushed minerals recovered at the mine face or in a
quarry can be quite large, as indicated previously. It is not
uncommon for the uncrushed material to include significant
quantities, e.g. including 10% or more by weight, of pieces
larger than 6 inches across in their smallest dimension, ranging
up to so-called "coffin sizes."
FIG. 4 illustrates a crusher machine generally similar to
- 16 -
-` ~o~4451
that of FIGS. 1 and 3, but in FIG, 4 classification is obtained
; between the lighter fines and the heavier, larger particles.
Discharge conduit 26 is provided with two or more discharge
nozzles 34A and 34s so that the lighter fines discharge ~ ~
through the nearer nozzle 34A and the heavier particles dis- -
charge through the more remote nozzle 34B. Two or more output
conveyor belts 36A and 36B are provided for carrying away the
; fines and the larger particles, respectively.
The nozzles 34A and 34B may also be arranged to discharge
both fine and heavier particles to the same conveyor belt.
Heretofore, it has been conventional practice to charge a
crusher from a scalping conveyor. Such conveyor discards fines
and feeds larger particles into the inlet of the crusher. The
output conveyor under the crusher passes first under the fines
discharge outlet of the scalping conveyor, laying down a layer
of fines thereon, and then passes under the discharge outlet
j of the crusher to receive the crushed product, including both
'~ large and small pieces. The previously placed layer of fines
on the conveyor cushions the shock of the larger crushed pieces
from the crusher, thus protecting and extending the life of the
~5 conveyor belt. In accordance with the present invention, it is ~ :
,~ i .
not necessary to pass the conveyor belt under both a scalping
conveyor and the bottom of the crusher. The nozzles 34A and B
may be so oriented relative to their common output conveyor,
so that nozzle 34A lays down a protective layer of fines on
the belt upstream of nozzle 34B. Thus, a scalping conveyor
is no longer required.
In the preferred means and method of operation correspond-
ing to the FIG 4 embodiment, the rotor in the machine housing
strikes, reduces and propels outwardly from the rotor a stream ~ `
:
- 17 -
10~4451
of solid material including lighter and heav-ier pieces. Means
integral with and/or separate from the rotor are provided for
generating a flow of air and for causing said stream and flow
to enter discharge chute 26 together. The latter defines a
first confined path away from the rotatable means for receiving
the stream and causing it to continue in motion generally in the
direction in which it is impelled by theblows of the impact
members~ at least until it passes beyond discharge nozzle 34A.
Said nozzle defines a path diverging from the discharge chute 26,
for diverting at least a portion of the air flow and at least a
; portion of the lighter pieces in the stream together from the
discharge conduit. Discharge chute 26 may include a lower
confining member 28A which has an upwardly sloping or curving
! surface extending from the downstream end of impact surface 24,
along a path elevated above a tangent line T", as discussed with
regard to FIG. 1. If sufficient separation of fines is obtained
at nozzle 34A, only a slight tendency for moist fines to accumu-
~ late on member 28A is found to exist on the upstream side of
-~ nozzle 34A. Thus, the surface of member 28A may be dropped
` 20 beyond nozzle 34A, if desired, to be coincident with tangentiT"
without danger of substantial clogging. In practice, it has
been found expedient to continue the sloping or curving surface
of member 28A all the way up the discharge chute.
The desired air flow can be generated by the rotating
impact members themselves and/or by suitable fans. The heaviest
pieces thrown off by the rotor will maintain their velocity
in the direction in which they are propelled for a relatively
long distance. The lighter pieces, having a lower mass-to-surface
ratio, tend to lose their forward velocity more rapidly. More-
over, the flow of air departing through nozzle 34A effects a
- 18 -
. .
~` ` 10~44S:~
more efficient capture and separation of the lighter pieces.
In order to insure that there is a sufficient flow of air
into nozzle 34A, the nozzle 34B may be fitted with an air
lock, or the nozzle 34A may have an air tight connection
with a suitable receptacle in which suction is generated by
a fan or other means.
FIG. 5A shows an enlarged view of the lower surface
or confining member of the discharge chute, identified as
elements 28, 52, 122 and 28 in FIGS. 1 to 4, respectively.
A portion 24' of the impact surface identified as elements
24, 58 and 80 in FIGS. 1 to 4 is shown, along with tangent T
extending from the downstream end of impact surface 24. As
previously discussed, if lower surface member 28 is made -~
coincident with tangent T, clogging near end A of the dis-
charge chute is frequently experienced. It has been found
that elevating the lower surface of the discharge chute
above the tangent T can reduce or substantially eliminate
clogging at end A.
Element 28a may be a flat plate which is elevated
20 relative to tangent T at an angle B, which is preferably -
between zero and approximately ten degrees in magnitude, as
shown in FIG. 5A. As pieces of crushed material are thrown
out of the crusher by the impact members, many will follow
paths generally parallel and closely adjacent to tangent
line T and eventually glance off the surface of element 28a, -
as indicated. This repeated contact with the surface of ele-
ment 28a scours the surface of fine particles as they settle,
thus preventing clogging. The greater the elevation of element
28a relative to tangent T, the greater will be the scouring
effect; however, elevations between zero and approximately ten
degrees are preferred. At highe~-elevations, the wear on sur-
face 28a may become excessive; furthermore, a significant amount
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of material may tend to rebound into the crusher where its size
is again reduced perhaps unnecessarily. Of course, where the
tendency of a particular material to clog is high, the elevation
of element 28a may have to be increased to obtain the desired
scouring effect, with concomitant increases in wear and material
rebound.
An alternative lower surface element 28b is shown in
FIG 5B. Element 28b is involute in shape and extends from
point A at the lower end of the discharge chute to point B at
the upper end, so that the surfaces of both elements 28a and 28b
begin and terminate in essentially the same locations. The more
gradual upward rise of element 28b relative to element 28a pro-
vides an adequate scouring effect to prevent clogging, yet
minimizes both obstruction of flow up the discharge chute and
wear on its lower surface. As shown in FIG. 5D, the surface of
element 28d also may be a simple upward curve having a constant
radius of curvature; however, an involute form as in FIG. 5B is
preferred. By "involute" is meant simply that the radius of
curvature of the surface is decreasing continuously from A to B.
This changing curvature of the surface results in increased
centripetal force acting on particles skimming along the curved
surface even as their tangential velocity decreases, which in-
creases the scouring effect and eliminates adhesion of the
particles. Both the involute and constant radius surfaces may
be made from a continuous plate of material, as shown in FIGS
5B and SD. Alternatively, they may be made from a series of
flat plates of progressively greater pitch relative to T joined
to approximate the involute or curved surfaces, without
departing from the teachings of the invention, as shown in
FIGS 5C and 5E It is contemplated that in the preferred
- embodiments, these types of lower surfaces for the discharge
chute will substantially reduce or eliminate clogging
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or accumulation of material at the discharge chute inlet;
however, other variations may occur to one skilled in the art
without departing from the scope of the invention.
Although practical difficulties have arisen in the past
in respect to economically conveying such crushed materials to
the surface or in crushing them economically and conveniently
in the quarry or at the mine face, such difficulties should be
reduced by the present invention. The present invention pro-
vides crushing apparatus which is simple, easy to load, poten-
tially portable and not dependent on a high supporting frameor trench for discharging to a conveyor. The disclosed appara-
tus will crush and discharge moist minerals without significant
clogging. Thus, it is now perfectly feasible to use a modest-
width belt conveyor, which is economical compared either to the
use of trucks or the use of other kinds of conveyors previously
considered necessary, to transport the crushed output directly
- from the crushing machine to the surface above or surrounding
the mine or quarry. Thus, for instance, in the case of lime-
stone, the crushed product may consist of particles of the order
of 6 inches or less in their maximum dimension.
;~ Based on the principles of the invention disclosed herein,
those skilled in the art will readily develop other embodiments,
all of which are intended to be protected by the appended claims.
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