A granulating apparatus particularly adapted for advanced ceramic materials having a granulation vessel with a cylindrical main body in which are coaxially-mounted rotatably an annular cage-like stirring rotor having peripheral stirring blades and a central impulse rotor having impulse blades and pins. The stirring blades are mounted in diverging pairs relative to their rotational direction to channel charge material axially centrally within the container, while the impulse blades are V-shaped convergingly in their rotational direction to impel charge material both radially and axially outwardly within the vessel, for enhanced charge material circulation. Nozzles mounted on the end cover of the vessel inject agglomerating liquid axially into the open granulation area between the rotors for direct impingement of liquid essentially only onto the charge material. The interior wall surface of the container, the stirring blades, and the impulse blades and pins have working surfaces formed of suitable wear resistant, non-contaminating material to facilitate use of the apparatus for advanced ceramic granulation applications.

BACKGROUND OF THE INVENTION 
The present invention relates generally to granulating apparatus and, more 
specifically, to such apparatus of the wet aggitative type adapted for 
forming powder materials, particularly advanced ceramic and similar 
valuable materials, into granules utilizing an agglomerating liquid. 
In various and diverse technologies, raw material processing conventionally 
requires the initial processing of raw material in powder form into larger 
agglomerated granules which may be more easily handled. Preferably, such 
agglomerated granules should be substantially spherical in shape and as 
uniform as possible in composition and density for ease of flowability and 
handling of the granules and to enhance the quality of end products formed 
therefrom. The formation of such uniform granules is particularly 
important in the preliminary processing of materials utilized in the 
emerging technological field of advanced ceramics. By way of example, such 
materials include alumina, silicon carbide, silicon nitride, barium 
titanate, various metal oxides, cermets such as tungsten carbide, 
partially stabilized zirconia, and cubic boron nitride. Advanced ceramic 
materials such as the foregoing find such highly technological 
applications as in the ferrite cores utilized in the deflection yokes for 
cathode ray tubes, adiabatic diesel engines and ceramic turbine engines, 
ceramic gas sensing devices, certain catalyst carriers and substrates, and 
various engineering ceramic applications such as high speed cutting tools, 
grinding media and the like. Such materials are conventionally formed into 
end products by a dry pressing or compacting operation. However, as 
initially processed, such materials are in a powdered form which 
characteristically is light, fluffy and therefore unmanageable and 
unsuitable for pressing operations. Accordingly, it is conventionally 
necessary to first form the powdered material into uniform granules which 
may be more readily handled and processed. Such advanced ceramic materials 
also are relatively expensive and valuable and, for the specialized and 
highly technological applications to which they are typically put, must be 
of optimum purity to insure a high degree of quality in the end product. 
Accordingly, the aforementioned requirements of uniform granule shape, 
composition and density are particularly acute and important in this 
field. 
Various forms of granulating apparatus which have been developed over past 
years have proved entirely unsuitable and unacceptable for formation of 
granules of advanced ceramic materials. So-called spray dryers are 
currently employed widely for the mass production of advanced ceramic 
granules. In spray dryers, a slurry composed of powdered raw material and 
a binder or other agglomerating liquid is continuously sprayed in 
essentially discrete droplet or globular form continuously in a downward 
direction into the top end of an upright hollow vessel while heated drying 
air is directed upwardly within the vessel to drive off the agglomerating 
liquid thereby transforming the globules into essentially dry granules of 
the powdered material. While this apparatus produces generally uniform 
spherical granules having acceptable flowability characteristics and 
providing acceptable suitability for dry pressing operations, it is 
difficult to produce relatively dense granules due to the heat-induced 
evaporation of the agglomerating liquid which tends to cause outward 
migration of the finer particles of the powdered material toward the 
granule surface and thereby often produces hollow granules. Additionally, 
the operation of the apparatus is highly energy intensive, requiring 
approximately a 50% moisture level in the slurry for acceptable 
granulation and accordingly requiring a considerable amount of drying 
energy. As a result, the ratio of granule output to energy consumed is 
unacceptably low. The substantial drying requirements of such apparatus 
generally also require that the apparatus be undesirably large and bulky. 
Furthermore, since the granulation process performed by such apparatus is 
a continuous one, the apparatus is basically unsuitable for use in forming 
small quantities of granules. When it is desired to change the powdered 
material being granulated, it is of course necessary to clean the entire 
apparatus which is difficult and time consuming to do and often in any 
event results in cross contamination from one material to the next. 
Extruding machinery is also available for forming moistened powder material 
into generally cylindrical pellet-type form by the forced extrusion of the 
material through a die plate or screen. Disadvantageously, it is difficult 
to produce pelletized granules by this operation to smaller than 
approximately a 0.7 mm. diameter due to rapid resultant wearing of the 
screen or die plate and concomitant contamination of the pelletized 
granules. Moreover, the cylindrical shape of the pellets significantly 
restricts their flowability and, as a result, such pellets are often 
further processed in a spheronizing vessel wherein the pellets are 
repetitively beaten against the vessel walls by a rotating plate to deform 
and plasticize the pellets into spherical form. 
Disintegration-type granulating machinery is also available for breaking 
large agglomerations of material into smaller pieces, but such apparatus 
produce generally unacceptable irregular and poorly flowable granule 
shapes and also suffer significant losses of relatively fine particles 
resulting in a low granule yield rate. 
Fluidized bed granulating machines have been developed which essentially 
combine the functions of an extruder, a spheronizer and a dryer for 
granule formation. In such apparatus, powdered raw material is fed into a 
cylindrical vessel having a stationary screen or plate with openings 
therethrough, the powdered material being treated with an agglomerating 
liquid spray on the charge side of the screen or plate while heated drying 
air is forced through the screen or plate openings from the opposite side 
thereof to form the powder into dry granules. Disadvantageously, such 
granulating apparatus produces a widely varying range of granule shapes 
and sizes which inhibit good flowability of the granules. The apparatus is 
often subject to rapid component wearing with resultant granule 
contamination, and also is not susceptible of accurate control and 
reproducibility of granule size. 
In another form of aggitative-type granulating apparatus, a charge of 
powdered material is processed in batch form in a vessel having a rotating 
outer annular mixing or stirring rotor and an inner impulse rotor 
therewithin for compatibility circulating and mixing the powdered charge 
material, with an agglomerating liquid spray being provided for forming 
the powder material into granules as circulation progresses. To enhance 
the powdered material distribution and granule formation, blade-like 
implements are typically provided on each rotor and the rotors may be 
rotated in opposite directions with the central impulse rotor being 
operated at a greater speed than the outer stirring rotor. Examples of 
this type of granulating apparatus are disclosed in Japanese Patent 
Publication Nos. 58-12050, 59-21649, 59-55338, and 59-59239, commonly 
owned with the present invention. While these apparatus are acceptably 
operative for granule formation, such apparatus produces widely ranging 
granule sizes with poor capability for accurate repeatable control of 
granule size and such apparatus also suffers rapid wearing of its internal 
operating components with attendant contamination of the granules formed, 
all of which makes this apparatus generally unacceptable for forming 
granules of advanced ceramic and other valuable materials. 
It is accordingly an object of the present invention to provide an improved 
granulating apparatus of the aggitative type last above-described, which 
is capable of repeatably accurate production of spherical granules of 
uniform density and composition and high purity without significant 
contamination, thereby being uniquely suitable for advanced ceramic 
granule formation. 
SUMMARY OF THE INVENTION 
The granulating apparatus of the present invention basically includes a 
granulation vessel having a material charge port and a granule discharge 
port, an annular stirring rotor rotatably disposed within the vessel for 
circulating charge material and an impulse rotor rotatably disposed within 
the vessel within the stirring rotor axially parallel therewith for 
outwardly dispersing charge material. 
According to one aspect of the present invention, the apparatus provides 
for wet-type granulation of powder materials utilizing an agglomerating 
liquid. For this purpose, the stirring rotor and the impulse rotor define 
an annular granulation work area radially therebetween within the vessel, 
the work area being unrestricted by either the stirring rotor or the 
impulse rotor at one corresponding axial end thereof. The vessel includes 
an end wall adjacent such corresponding axial end of the stirring and 
impulse rotors and a liquid-emitting device, preferably a spray nozzle, is 
supported by the end wall axially adjacent the granulation work area for 
unrestricted emission of agglomerating liquid into the work area in a 
generally axial direction relative to the stirring and impulse rotors for 
impingement of the liquid directly and essentially only on the charge 
material within the vessel. Preferably, the spray nozzle arrangement is 
adapted for producing a conical spray pattern of the agglomerating liquid 
and may be selectively operated for either pressurized liquid spray 
applications or pneumatically-impelled liquid spray applications. 
According to another aspect of the present invention, the impulse rotor and 
the stirring rotor are cooperatively configured for producing both axial 
and radial circulation of the charge material to enhance the dispersion 
thereof within the annular granulation work area. For this purpose, the 
impulse rotor is provided with a plurality of impulse members arranged 
thereabout and configured to disperse the charge material both radially 
and axially outwardly from the impulse rotor, while the stirring rotor 
includes a plurality of stirring members arranged thereabout and 
configured to direct the charge material axially inwardly of the stirring 
rotor. Preferably, a plurality of impulse blades are utilized as the 
impulse members, the blades being spaced circumferentially about the 
impulse rotor and extending radially outwardly for substantially the full 
axial extent thereof. Each impulse blade is generally V-shaped along its 
axial length convergingly in the circumferential direction of rotation of 
the impulse rotor to disperse the charge material axially outwardly from 
the impulse rotor. A plurality of stirring blades are utilized as the 
stirring members on the stirring rotor and are arranged circumferentially 
thereabout in axially adjacent pairs oriented divergingly with respect to 
one another in the circumferential direction of rotation of the stirring 
rotor to direct the charge material axially inwardly of the stirring 
rotor. 
In the preferred embodiment, the vessel is generally cylindrical and is 
disposed with its axis extending generally horizontally. The stirring 
rotor is disposed generally coaxially within the vessel with the stirring 
blades arranged in close proximity to the vessel and a drive arrangement 
is provided for rotating the stirring rotor at relatively slow speeds for 
causing the stirring blades to circulate the charge material within the 
vessel. Another drive arrangement is similarly provided for rotating the 
impulse rotor at relatively high speeds for causing the impulse blades to 
turbulently impel the circulated material dispersingly within the vessel. 
The impulse rotor also includes a plurality of impulse pins arranged 
intermediate the impulse blades and extending radially outwardly from the 
impulse rotor substantially beyond the impulse blades for impacting charge 
material within the vessel to control the size of granules formed of the 
material. 
According to another aspect of the present invention, the interior vessel 
wall and the working surfaces of the stirring blades, impulse blades and 
impulse pins of the stirring and impulse rotors, respectively, are formed 
of a material which is wear resistant and non-contaminating to the charge 
materials so that the granulating apparatus may be particularly adapted 
for use with advanced ceramic and other valuable charge materials. 
Preferably, the stirring blades are detachably mounted on the stirring 
rotor for ease of replacement when worn and are formed of an organic 
polymeric plastic material having a relatively high molecular weight, e.g. 
polyethylene, for suitable abrasion resistance and to permit any abraded 
particles released from the blades to be removed by heat application from 
granules formed of the charge material. The interior wall surface of the 
vessel may be coated or alternatively may be fitted with a removable 
lining, preferably of the same or a comparable material to the charge 
material. Similarly, the impulse rotor may be constructed of the same or a 
comparable material to the charge material, as by casting or molding or 
may be exteriorly coated with such material. The impulse pins of the 
impulse rotor may also be detachably mounted thereon for ready replacement 
when worn.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the accompanying drawings and initially to FIGS. 1 and 2, 
the granulating apparatus of the present invention is indicated generally 
at 10 and basically includes a granulation vessel 12, a stirring rotor 14 
and an impulse rotor 16 rotatably disposed coaxially within the vessel 12, 
a drive arrangement indicated generally at 18 for rotatably operating the 
stirring and impulse rotors 14,16, and a spray arrangement 20 for 
injecting agglomerating liquid into the vessel 12. 
The vessel 12 includes a substantially cylindrical hollow main container 
body 22 supported in axially horizontal disposition by an appropriate 
frame structure, indicated representatively at 24. One axial end of the 
container body 22 is substantially closed by an integrally affixed radial 
end wall 26 and an end cover 28 is pivotably attached to the body 22 at 
its opposite axial end for opening and closing access to the body 
interior. Threaded locking bolts 30 mounted at spacings about the 
periphery of the cover 28 mate with corresondingly tapped flanges 32 
arranged about the corresponding end of the body 22 to sealingly lock the 
cover 28 in its closed position. A material charge port 34 is formed 
centrally in the circumferential periphery of the body 22 at the upwardly 
facing side thereof and an upright material charging superstructure 36 is 
affixed to the container body 22 about the charge port 34. The material 
charging superstructure 36 includes a frusto-conical charge chute 38 
opening at its lower end into the charge port 34 and being closed at its 
upper end by an openable material charge inlet 40 and an exhaust filter 
42. A granule discharge port 44 is formed centrally in the downwardly 
facing side of the circumferential periphery of the container body 22 with 
a discharge chute 46 mounted to the container body 22 about the discharge 
port 44 and extending downwardly therefrom. A piston 48 is slidably 
disposed within the discharge chute 46 and is operated by a connecting rod 
50 for opening and closing the discharge port 44. 
The stirring rotor 14 is constructed of an annular cage-like configuration 
having a supporting radial end disk 52 and an end ring 54 arranged in 
spaced coaxially parallel relation with a plurality of support bars 
extending at spacings axially between the corresponding outer peripheries 
of the end disk 52 and end ring 54. A plurality of stirring blades 58 are 
supported at spacings about the outer circumferential periphery of the 
stirring rotor 14 by mounting legs 60 which extend radially outwardly from 
the support bars 56. Each stirring blade 58 is of an essentially arcuate 
platelike configuration having a radially outwardly oriented planar body 
58' with an arcuate radially-outward scraper edge 58" conforming to the 
cylindrical interior of the container body 22. The stirring blades 58 are 
mounted to the support bars 56 in axially adjacent pairs 58A,58B oriented 
divergingly with respect to one another in the circumferential direction 
of rotation of the stirring rotor 14, as indicated by the directional 
arrow A in FIGS. 2 and 4. The diametric dimension of the stirring rotor 
between the outer edges 58" of diametrically opposed stirring blades 58 is 
approximately the same as or only slightly smaller than the interior 
diameter of the cylindrical container body 22. The stirring rotor 14 is 
supported rotatably within the hollow interior of the container body 22 in 
a cantilevered fashion by a tubular support shaft 62 which extends 
coaxially outwardly from the end disk 52 through the container end wall 26 
and is rotatably journaled in a suitable support structure, indicated 
representatively at 25 in FIG. 5, of the drive arrangement 18. 
The impulse rotor 16 includes an elongate cylindrical rotor body 64 having 
a plurality of impulse blades 66 and impulse pins 68 arranged about the 
outer circumferential periphery of the rotor body 64. The impulse blades 
66 are affixed to the rotor body 64 at substantially equal circumferential 
spacings thereabout with each blade 66 extending radially outwardly from 
the rotor body 64 for substantially the full axial length thereof, each 
impulse blade 66 being of an essentially platelike construction configured 
generally V-shaped along its axial length convergingly in the 
circumferential direction of rotation of the impulse rotor 16, as 
indicated by directional arrow B in FIGS. 2 and 4. The impulse pins 68 are 
affixed to the rotor body 64 in radially outwardly extending orientation 
in V-shaped rows equidistantly intermediate the impulse blades 66. Each 
impulse pin 68 is of an elongated, essentially triangularly segmented 
cross-sectional shape of a length considerably greater than the radial 
dimension of the impulse blades 66 to extend substantially radially beyond 
the impulse blades 66, each pin 68 having a longitudinal leading edge 68' 
facing squarely in the direction of rotation of the impulse rotor 16. The 
diametric dimension of the impulse rotor 16 between the radially outward 
tips of diametrically opposed impulse pins 68 is smaller than the inner 
diameter of the supporting cage of the stirring rotor 14 and the impulse 
rotor 16 is supported rotatably within the hollow interior of the 
container body 22 coaxially within the stirring rotor 14 in cantilever 
fashion by a support shaft 70 which extends coaxially outwardly from one 
end of the rotor body 64 through the container end wall 26 and is 
rotatably journaled within the support structure 25 of the drive 
arrangement 18 coaxially within the tubular support shaft 62 for the 
stirring rotor 14. An annular granulation work area 72 is thus defined 
within the container body 22 between the circumferential periphery of the 
impulse rotor 16 and the stirring blades 58 of the stirring rotor 14, the 
granulation work area being essentially open and unrestricted between the 
impulse rotor 16 and the supporting end ring 54 of the stirring rotor 14 
at the axial end of the container body 22 adjacent its end cover 28. 
The drive arrangement 18 is best seen in FIG. 5 and basically includes 
individual drive motors 74,76 for the stirring and impulse rotors 14,16 
operating independently through respective drive chains or belts 78,80 on 
respective drive wheels 82,84 mounted to the outward ends of the 
supporting shafts 62,70 of the stirring and impulse rotors, respectively. 
For reasons to be more fully explained hereinafter, the drive train to the 
impulse rotor 16 is arranged to effect rotation thereof at relatively high 
speeds in the range, for example, of 500 to 8,000 revolutions per minute, 
while the drive train to the stirring rotor 14 is arranged to effect 
rotation thereof at relatively slow speeds in the range, for example, of 
10 to 50 revolutions per minute. The respective drive trains to the 
stirring and impulse rotors 14,16 are also arranged to effect rotation 
thereof in opposite directions with respect to one another, as indicated 
in FIGS. 2 and 4 by directional arrow A for the stirring rotor 14 and 
directional arrow B for the impulse rotor 16. 
The spray arrangement 20 includes one or more spray nozzles 86 mounted on 
the end cover 28 of the container body 22 immediately axially adjacent the 
open granulation work area 72 in the unrestricted end open portion thereof 
radially between the impulse rotor 16 and the supporting end ring 54 of 
the stirring rotor 14 to one lateral side of the impulse rotor 16. As best 
seen in FIG. 5, agglomerating liquid, which may be any conventional liquid 
binder, water or other suitable agglomerating liquid, is supplied to the 
spray nozzles 86 from a liquid reservoir 88 by a suitable liquid pump 90. 
A flow meter 92 is provided in the liquid supply line to permit accurate 
control of the rate of liquid supply to the nozzles 86. The pump 90 and 
flow meter 92 are cooperatively set to supply the agglomerating liquid at 
a desired pressure and flow rate to provide a continuous liquid supply to 
the nozzles 86. A supply of compressed air or other suitable compressed 
gas 94 is also connected to the spray nozzles 86 with an appropriate 
in-line valve 96 and air flow meter 98 for pneumatic operation of the 
nozzles 86 for emitting an atomized or aspirated spray of the 
agglomerating liquid in an axial direction into the granulation work area 
72. As desired, a liquid pump of a higher pressure capacity may be 
employed with the nozzles 86 or other appropriate nozzles for producing a 
pressurized liquid spray without pneumatic assistance. Preferably, the 
nozzles 86 are of the type adapted to emit the agglomerating liquid in a 
solid conical spray pattern. 
In operation, the granulating apparatus 10 is utilized for the batch 
processing of powdered charge material into agglomerated granules of a 
predetermined desired spherical diameter. Initially, the container body 22 
of the vessel 12 is charged with a measured quantity of the powdered 
charge material through the inlet 40 of the superstructure 36 and the 
liquid reservoir 88 is charged with a suitable quantity of a selected 
binder or other agglomerating liquid. The drive arrangement 18 is then 
actuated to initiate counter-rotation of the stirring and impulse rotors 
14,16 respectively at relatively slow and relatively fast rotational 
speeds, as aforementioned. The spray arrangement 20 may be initially left 
deactuated for an initial period of time to permit the stirring and 
impulse rotors 14,16 to mix the charge material into a homogenous powder, 
particularly in such cases in which the charge powder includes two or more 
differing materials. With the liquid flow meter 92, and the air flow meter 
98 if utilized, at pre-set positions, the liquid pump 90 is energized and 
the valve 96 is opened to inject sprays of the agglomerating liquid into 
the granulation work area 72 in an axial direction to wet the powdered 
charge material. 
The particular constructions of the stirring and impulse rotors 14,16 in 
conjunction with the axial agglomerating liquid spray by the nozzles 86 
cooperate to provide unusually rapid and precise formation of essentially 
spherical granules of consistently uniform density and composition. The 
stirring blades 58 of the stirring rotor 14 are effective to circulate the 
powdered charge material within the container body 22 by progressively 
scraping and conveying upwardly the powdered material residing lowermost 
within the container body 22 and gravitationally depositing the material 
in the region of the impulse rotor 16 and the upper level of the quantity 
of charge material in the direction of rotation of the stirring rotor 14. 
At the same time, the rapid rotation of the impulse rotor 16 is effective 
to tubulently impel the circulating charge material to disperse it within 
the container body 22 to create and maintain an axially centralized zone 
of fluidized suspension of the charge material. The natural centrifugal 
forces created by rotation of the impulse rotor 16 naturally tend to impel 
the charge material radially outwardly therefrom, while the V-shaped 
configuration of the impulse blades 66 effectively also direct the 
powdered material in an axially outward direction from the impulse rotor 
16. At the same time, the orientation of the paired stirring blades 58 
divergingly in the direction of rotor rotation are effective to channel 
and direct the charge material toward the axial center of the container 
body 22. In this manner, the stirring and impulse rotors 14,16 cause the 
charge material to be circulated within the container body 22 in both 
radial and axial directions for enhanced circulation, dispersion and 
suspension of the charge material particularly within the granulation work 
area 72 between the rotors 14,16. 
As the charge material is being thusly circulated within the container body 
22, the spray nozzles 86 continuously impinge the circulating charge 
material within the granulation work area 72 with the agglomerating 
liquid, the continuously recirculating suspension of the charge material 
effected by the stirring and impulse rotors 14,16 cooperatively insuring 
substantially uniform wetting of all of the charge material with the 
liquid. Accordingly, as the operation of the granulation apparatus 10 
progresses in this manner, the wetted powdered charge material begins to 
adhere into granules, which are progressively densified, shaped and 
disintegrated into essentially uniform spheres by the continuing impulsive 
forces created by the impulse rotor 16. As the granulation process 
progresses, the radial impulse pins 68 of the impulse rotor 16 provide a 
disintegrational effect on the agglomerating granules to reduce and 
control the size of the granules as well as to aid further in the 
densification and shaping thereof. Particularly, the triangular 
cross-secitonal shape of the impulse pins 68 and their orientation with 
one leading edge 68' facing in the rotational direction of the impulse 
rotor 16 are especially effective to disintegrate the agglomerating 
granules. Importantly, the axial direction of the emitted liquid spray 
from the nozzles 86 is effective to impinge the agglomerating liquid 
directly onto the dispersed and suspended charge material within the 
granulation work area without any significant impingement of the liquid on 
the surfaces of the stirring and impulse rotors 14,16, owing to the 
coaxially cantilevered mounting of the stirring and impulsed rotors 14,16 
and the open annular construction of the stirring rotor 14 at the end 
thereof adjacent the nozzles 86. Accordingly, in contrast with 
conventional granulating apparatus wherein liquid typically is injected 
through the material charge chute or structure, no tendency exists in the 
present apparatus for the charge material to agglomerate on the rotors 
themselves. As desired, one or more compressed air nozzles (not shown) may 
be mounted on the circumferential periphery of the container body 22 to 
direct compressed air into the peripheral interior areas of the body 22 to 
prevent any accumulation of the powdered material on the interior wall 
surfaces of the body 22. 
After a relatively short period of treatment in the above manner, usually 
in the range of ten to fifteen minutes, the granulation process is 
completed to produce uniform, dense, spherical, free flowing granules of 
the original charge material. As will be understood by those persons 
skilled in the art, granule size, density and like parameters can be 
selectively controlled by varying the rotational speeds of the stirring 
and impulse rotors 14,16, the agglomerating liquid material utilized, the 
rate of agglomerating liquid spray, and the overall time period of the 
granulation process. 
The enhanced uniformity of granules produced by the present granulating 
apparatus makes it particularly useful for the granulation of advanced 
ceramic and similar valuable material with which it is particularly 
important that a minimal range of variations exist in granule size, shape, 
density, composition and similar characteristics. As previously mentioned, 
it is additionally important in advanced ceramics processing that optimal 
purity of the material be maintained and, accordingly, the risk of 
introducing contaminating materials must be kept to a minimum. For this 
purpose, the present granulating apparatus also provides for all of the 
interior working surfaces within the container body 22 to be of a suitable 
material which is both wear resistant to the impulsive and frictional 
forces occurring during granulation and non-contaminating to the advanced 
ceramic or other similarly valuable charge material. Particularly, with 
reference to FIGS. 6-9, the granulating apparatus 10 provides for each of 
the interior circumferential wall surface of the container body 22, the 
stirring blades 58 of the stirring rotor 14, and the impulse blades and 
pins 66,68 of the impulse rotor 16 to be of such suitable wear resistant 
and non-contaminating materials. 
As seen in FIG. 6, the present invention provides a cylindrical sleeve or 
liner 100 of an exterior diametric dimension corresponding to the interior 
diameter of the cylindrical container body 22 and having 
circumferentially-spaced openings 102,104 formed centrally in the 
circumferential surface of the sleeve 100 to permit the sleeve 100 to be 
selectively fitted snugly within the container body 22 with the openings 
102,104 corresponding to the charge and discharge ports 34,44 therein and 
to be selectively removed and replaced as desired. The sleeve 100 may be 
formed of any suitable wear resistant, non-contaminating material for the 
particular granulating application to which the apparatus 10 is to be put. 
For advanced ceramic applications, it is preferably that the sleeve 100 be 
formed of the same advanced ceramic material as is processed within the 
granulating apparatus 10. Alternatively, the container body 22, as well as 
the other interior surfaces of the granulation vessel 12 as desired, may 
be formed with a diffusion/plasma coating of advanced ceramic or other 
suitable wear resistant, non-contaminating material. 
Similarly, the exterior surfaces of the impulse rotor 16 are preferably 
formed of the same advanced ceramic material as that to be processed in 
the apparatus 10. For this purpose, the impulse rotor 16 may be cast or 
otherwise molded of selected advanced ceramic material or may be provided 
with a diffusion/plasma coating of the exposed rotor body 64, impulse 
blades 66 and impulse pins 68. The impulse pins 68 will be subjected to 
the greatest impulsive, abrasive and frictional forces during normal 
operation of the granulating apparatus 10 and, accordingly, it is 
contemplated that ceramic or ceramic-coated impulse pins 68 may be 
detachably and replaceably mounted to the rotor body 64 as shown in FIGS. 
7 and 8. For this purpose, the cylindrical body 64 of the impulse rotor is 
provided with a plurality of circular openings 106 spaced about its 
periphery at the designated locations for the impulse pins 68 and a 
corresponding plurality of cup-like pin holders 108 are welded to the 
rotor body 64 generally flush with the outer circumferential surface 
thereof to present radially outwardly opening recessed areas 110 for 
receiving the impulse pins 68. Each detachable impulse pin 68 has a 
frusto-conically shaped root portion 112 adapted to be received within the 
recessed area 110 of a respective pin holder 108. The opposite end of the 
impulse pin 68 is of the generally triangularly segmented shaped described 
above. An exteriorly-threaded bushing 114 is provided to encircle the 
conical root portion 112 of the pin 68 and to threadedly engage a 
correspondingly interiorly threaded portion of the pin holder 108 to 
retain the root portion 112 within the recessed area 110 of the holder 
108, the bushing 114 being provided with a hexagonal nut portion 116 to 
facilitate easy tightening and removal of the bushing 114 for ready 
installation and removal of the pin 68 as desired. A conical spring washer 
118 is provided within the radially inward bottom surface of the recessed 
area 110 of the holder 108 to bias the pin 68 radially outwardly to 
maintain snug engagement between the root portion 112 of the pin 68 and 
the bushing 114. 
For the same purpose, the stirring blades 58 of the stirring rotor 14 are 
detachably and replaceably mounted on the support bars 56, as shown in 
FIG. 9. For this purpose, each stirring blade 58 has a mounting bracket 
120 affixed adhesively or by screws, as desired, to the rearward side of 
the body 58' of the stirring blade 58 facing away from the direction of 
rotation of the stirring rotor 14. The mounting bracket 120 includes an 
essentially square or rectangular sleeve portin 122 adapted to receive the 
projecting end of one of the mounting legs 60 of the stirring rotor 14, 
each of which mounting legs 60 is compatibly of a corresponding 
rectangular or square cross-sectional shape. The sleeve portion 122 of the 
mounting bracket 120 has a threaded opening 124 formed therethrough to 
receive a correspondingly threadedly bolt 126 for tightening into 
engagement with the mounting leg 60 to snugly secure the stirring blade 
and bracket assembly to its respective mounting leg 60. As will be 
understood, the sleeve portion 122 may be slidably positioned as desired 
along the compatible length of the mounting leg 60 upon assembly to 
thereby selectively determine the clearance between the edge 58" of the 
stirring blade 58 and the interior wall surface of the container body 22 
of the granulation vessel 12. 
As desired, the stirring blades 58 may be formed also of a selected 
advanced ceramic material, in which case it will be understood that the 
overall outer diameter of the stirring rotor 14 between diametrically 
opposed stirring blades 58 must be maintained within precise tolerances to 
insure a clearance of a relatively close spacing between the stirring 
blades 58 and the sleeve 100 or the interior circumferential wall surface 
of the container body 22 while preventing any abrasive contact 
therebetween. Alternatively, the stirring blades 58 may be formed of a 
suitable plastic material to permit the blades 58 to operate within the 
container body 22 in scraping surface contact with the sleeve 100 or the 
interior circumferential wall surface of the container body 22. For this 
purpose, it has been found that the particular plastic material utilized 
must be carefully selected to have a molecular structure which provides a 
high degree of wear resistance to surface contact with sleeve 100 or the 
container body 22 while also being adapted to release only minute 
particles of the plastic material in response to wearing so that the 
plastic material may be readily removed by heat application from any end 
product produced from the advanced ceramic or other charge material 
without significantly affecting the quality of the end product. It has 
been found that a high density, high molecular weight polyethylene or 
polyimide performs well for such purposes. 
It will therefore be readily understood by those persons skilled in the art 
that the present invention is susceptible of a broad utility and 
application. Many embodiments and adaptations of the present invention 
other than those herein described, as well as many variations, 
modifications and equivalent arrangements will be apparent from or 
reasonably suggested by the present invention and the foregoing 
description thereof, without departing from the substance or scope of the 
present invention. Accordingly, while the present invention has been 
described herein in detail in relation to its preferred embodiment, it is 
to be understood that this disclosure is only illustrative and exemplary 
of the present invention and is made merely for purposes of providing a 
full and enabling disclosure of the invention. The foregoing disclosure is 
not intended or to be construed to limit the present invention or 
otherwise to exclude any such other embodiment, adaptations, variations, 
modifications and equivalent arrangements, the present invention being 
limited only by the claims appended hereto and the equivalents thereof.