Patent Publication Number: US-6209811-B1

Title: Roller-stator disperser

Description:
BACKGROUND OF THE INVENTION 
     This invention is generally directed to a dispersing apparatus for dispersing solid particles in a liquid medium. 
     A prior art “fluid energy” disperser is shown and described in U.S. Pat. No. 5,156,344. This prior art disperser utilizes a rotor assembly mounted within a stator assembly to disperse solid particles within a liquid medium. The rotor assembly is rotated within the stator assembly to disperse the solid particles within the liquid medium. 
     A prior art “mechanical energy” shot mill disperser is shown and described in U.S. Pat. No. 3,653,600. This prior art disperser utilizes steel shot which is retained in a mixing vessel and agitated by rotating impellers connected to a drive shaft to disperse the solid particles within the liquid medium. The apparatus has a rotor separator device connected to and driven by the drive shaft near the mixing vessel outlet to separate the steel shot from the finished product. 
     At times, it is desired to grind pigments in a batch mode, at an intensity greater than “fluid energy” dispersers can achieve, but in an easier and less complex manner than “mechanical energy” shot mills provide. The present invention provides such a disperser. Other features and advantages of the present invention will become apparent upon a reading of the attached specification in combination with a study of the drawings. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     A general object of the present invention is to provide a dispersing apparatus used to grind pigments in a batch mode, at an intensity which is greater than “fluid energy” dispersers can accomplish, and in an easier and less complex manner than “mechanical energy” shot mills can accomplish. 
     Another general object of the present invention is to provide a dispersing apparatus including an assembly having rollers which advance under shaft rotation and roll over a wet film of solids suspended in a liquid. 
     An object of the present invention is to provide a roller-stator disperser in which roller to stator dynamic pressure can be increased or decreased. 
     A further object of the present invention is to provide a roller assembly for a roller-stator disperser which allows the rollers to be positioned against or away from the stator assembly as a result of the viscosity/rheology of the slurry being processed. 
     Yet an even further object of the present invention is to provide a roller assembly for a roller-stator disperser which allows the rollers to move as they wear during use. 
     An even further object of the present invention is to provide a roller-stator disperser which uses a deflector to create pumping with a mixing vessel. 
     Briefly, and in accordance with the foregoing, the present invention discloses an apparatus for dispersing solid particles carried in suspension in a liquid medium. The apparatus includes a mounting frame, a rotatable agitator shaft connected thereto, a motor drive assembly carried thereby for rotating the agitator shaft, and a roller-stator assembly carried by the mounting frame. The roller-stator assembly includes a roller assembly and a stator assembly. 
     The stator assembly includes a plurality of stator support rods extending from the mounting frame and a stator ring attached to the stator support rods. The roller assembly is connected to the agitator shaft and is positioned within the stator ring. 
     The roller assembly includes a plurality of upper and lower support portions which form pairs and each of which has a roller positioned therebetween which is rotatable with respect to the pair and with respect to the stator ring. The upper and lower support portions can be affixed to the agitator shaft at the same angle relative thereto or at varying angles relative thereto. The upper and lower support portions have slots therein in which the respective roller is mounted such that the roller can move inwardly and outwardly relative to the agitator shaft. Such inward and outward motion can be radial. 
     A deflector is mounted below the stator ring such that when material passes through the stator ring, the material encounters the deflector and is recirculated for another pass through the disperser. The deflector can include vertical fins protruding upwardly therefrom to create pumping within the mixing vessel. 
     In a second embodiment, the stator ring includes a plurality of spaced apart members on an inner surface thereof. Each roller has a plurality of teeth which are capable of intermeshing with the spaced apart members as the roller assembly rotates relative to the stator assembly. 
     In addition, the stator ring can be provided with a plurality of venturi openings therethrough for allowing material to pass therethrough during dispersion. 
     In yet another embodiment, each roller can be provided with a tapered outer wall. Means for varying the position of the stator assembly relative to the roller assembly can be provided such that varying amounts of each said roller is in contact with the stator ring. 
     Other objects of the present invention will become apparent upon a reading of the attached specification in combination with a study of the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The organization and manner of the structure and operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, wherein like reference numerals identify like elements in which: 
     FIG. 1 is a side elevational view, shown partially in cross-section, of a dispersing apparatus which incorporates the features of the invention; 
     FIG. 2 is a top plan view of a roller-stator assembly which incorporates the features of a first embodiment of the invention; 
     FIG. 3 is a cross-sectional view of the roller-stator assembly of FIG. 2; 
     FIG. 4 is a cross-sectional view along line  4 — 4  of FIG. 2; 
     FIG. 5 is a top plan view, shown partially in cross-section, of a roller-stator assembly which incorporates the features of a second embodiment of the invention; 
     FIG. 6 is a cross-sectional view of the roller-stator assembly of FIG. 5; 
     FIG. 7 is a side elevational view, shown partially in cross-section, of a dispersing apparatus which incorporates the features of the invention; 
     FIG. 8 is a top plan view of a roller-stator assembly which incorporates the features of a third embodiment of the invention; 
     FIG. 9 is a top plan view of a roller-stator assembly which incorporates the features of a fourth embodiment of the invention; 
     FIG. 10 is a top plan view of a roller-stator assembly which incorporates the features of a fifth embodiment of the invention; and 
     FIG. 11 is a top plan view of a roller-stator assembly which incorporates the features of a sixth embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
     While the invention may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, specific embodiments with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that as illustrated and described herein. 
     The roller-stator assembly, generally denoted as reference numeral  20 , which incorporates the features of the present invention is used in a dispersing apparatus  22  to grind pigments in a batch mode, at an intensity which is greater than what “fluid energy” dispersers can accomplish, and in an easier and less complex manner than “mechanical energy” shot mills can accomplish. The roller-stator assembly  20  of the present invention bolts to a high speed disperser or can be attached to a rotor stator. 
     A first embodiment of the roller-stator assembly  20  is shown in FIGS. 2-4. A second embodiment of the roller-stator assembly  20   a  is shown in FIGS. 5 and 6. Third and fourth embodiments of the roller-stator assembly  20   b ,  20   c  are shown in FIGS. 8 and 9, respectively; and firth and sixth embodiments of the roller-stator assembly  20   d ,  20   e  are shown in FIGS. 10 and 11, respectively. Like elements in each embodiment are denoted with like reference numerals, with the like elements of the second embodiment being denoted with the suffix “a” after the reference numeral, like elements of the third embodiment being denoted with the suffix “b” after the reference numeral, like elements of the fourth embodiment being denoted with the suffix “c” after the reference numeral, like elements of the fifth embodiment being denoted with the suffix “e” after the reference numeral, and like elements of the sixth embodiment being denoted with the suffix “e” after the reference numeral. 
     FIG. 1 shows the roller-stator assembly  20  of FIGS. 2-4 mounted to a dispersing apparatus  22 . While the roller-stator assembly  20  of FIGS. 2-4 is shown mounted to the dispersing apparatus  22 , it is to be understood that any of the embodiments of the roller-stator  20   a ,  20   b ,  20   c ,  20   d ,  20   e  shown in FIGS. 2-6 and  8 - 11  can be mounted on the dispersing apparatus  22  shown in FIG. 1 in a like manner. The dispersing apparatus  22  shown in FIG. 1 includes a mounting frame  24 , a motor drive assembly  26 , and an agitator shaft  28  connected to the motor drive assembly  26 . The motor drive assembly  26  may include a variable speed motor  30  for driving the agitator shaft  28  through a belt and variable speed pulley arrangement  32 . 
     The roller-stator assembly  20  of the present invention is connected to a lower end of the agitator shaft  28 . The agitator shaft  28  and the roller-stator assembly  20  may be lowered into an operating position in an associated mixing tank  34  shown in phantom line in FIG. 1 by means of an associated hydraulic piston  36  which also forms part of the disperser apparatus  22 . 
     In each embodiment of the roller-stator assembly  20 ,  20   a ,  20   b ,  20   c ,  20   d ,  20   e , the agitator shaft  28  is connected to the center of the roller-stator assembly  20 ,  20   a ,  20   b ,  20   c ,  20   d ,  20   e  and defines a central axis of the roller-stator assembly  20 ,  20   a ,  20   b ,  20   c ,  20   d ,  20   e  The roller-stator assembly  20 ,  20   a ,  20   b ,  20   c ,  20   d ,  20   e  includes a stator assembly  38 ,  38   a ,  38   b ,  38   c ,  38   d ,  38   e  connected to and supported by the mounting frame  24  and a roller assembly  40 ,  40   a ,  40   b ,  40   c ,  40   d ,  40   e  connected to the lower end of and driven by the agitator shaft  28 . 
     Attention is now invited to the embodiment of the roller-stator assembly  20  shown in FIGS. 2-4. 
     The stator assembly  38  includes a horizontally positioned, upper stator support plate  42 , see FIG. 1, a horizontally positioned, lower stator support plate  44 , and a plurality of vertically extending stator support rods  46  interconnecting the upper and lower stator support plates  42 ,  44 . The stator support rods  46  can be airfoil shaped. The upper stator support plate  44  surrounds the agitator shaft  28  and is mounted to the mounting frame  24 . 
     A stator ring  46  is mounted to the lower stator support plate  44  and surrounds the agitator shaft  28 . The stator ring  46  includes a circular upper portion  48  and a circular lower portion  50  integrally formed with the upper portion  48  and which depends vertically downward therefrom. The inner wall of the upper portion  48  flares outwardly from the agitator shaft  28  and the inner wall of the lower portion  50  is vertical. In this embodiment, the stator ring  46  is solid and is preferably formed from heavy wall steel tubing or stainless steel tubing. 
     An annular spacer member  52  is provided between the flared upper portion  48  of the stator ring  46  and the lower stator support plate  44 . To mount the stator ring  46  to the lower stator support plate  44 , a plurality of screws  54  are provided and extend through the lower stator support plate  44 , through the spacer member  52 , and into the flared upper portion  48  of the stator ring  46  which overlaps the lower stator support plate  44 . 
     A stator ring plate is secured to the bottom end of the stator ring  46  by suitable means, such as welding. The stator ring plate  56  includes a horizontal upper portion  58  which is connected to the bottom end of the stator ring  46  by a plurality of screws  60  and a vertical lower portion  62  which depends downwardly from the upper portion  58 . The upper portion  58  has an aperture through the center thereof which opens into a passageway through the center of the lower portion  62 . In addition, a plurality of spaced apart openings  64  are provided through the upper portion  58  of the stator ring plate  56  for reasons described in further detail herein. 
     A deflector  66  surrounds the lower portion  62  of the stator ring plate  56 . The deflector  66  extends outwardly beneath the stator ring plate  56  such that the deflector  66  is beneath, but spaced from, the openings  64  in the stator ring plate  56 . An aperture is provided through the center of the deflector  66 . The upper surface of the deflector  66  gradually curves downwardly and outwardly from the lower portion  62  of the stator ring plate  56 . 
     An annular plate  68  is mounted between the deflector  66  and the lower portion  62  of the stator ring plate  56 . A plurality of screws  70  extend through a center portion of the deflector  66 , through the annular plate  68  and into the lower portion  62  of the stator ring plate  56  to mount the deflector  66  to the stator ring plate  56 . The position of the deflector  66  relative to the upper portion  58  of the stator ring plate  56  can be adjusted by backing off or tightening the screws  70  to move the deflector  66  away from or towards, respectively, the upper portion  58 . 
     An annular self-lubricating bearing  72  is mounted within the passageway through the lower portion  62  of the stator ring plate  56  for interaction with the roller assembly  40  as described herein and is seated between an inner portion of the annular plate  68  and an inner shoulder of the lower portion  62  of the stator ring plate  56 . 
     The roller assembly  40  includes a roller hub  74  mounted to the lower end of the agitator shaft  28  and a snubber  76  mounted to the bottom end of the roller hub  74 . Each of the roller hub  74  and the snubber  76  have a passageway through the center thereof. An elongated screw  78  is seated within the passageways and extends into a bore within the agitator shaft  28  to secure the snubber  76 , the roller hub  74  and the agitator shaft  28  together. The head of the screw  78  seats against an inner shoulder of the snubber  76  which protrudes into the snubber central passageway. The lower portion of the snubber  76  extends through the central aperture provided through the stator ring plate  56  and can engage the annular bearing  68 . 
     The roller assembly  40  further includes a plurality of pairs of upper and lower roller support portions  80 ,  82  which extend horizontally outwardly from the roller hub  74  toward the lower portion  50  of the stator ring  46 . As best shown in FIG. 2, three pairs of upper and lower roller support portions  80 ,  82  are provided. Each upper and lower roller support portion  80 ,  82  is generally planar and has an angled edge  84  along one side thereof, see FIG.  4 . When the roller assembly  40  is rotated, as described herein, the angled side edge  84  provides for an ease of rotation of the roller assembly  40  through the slurry. The upper and lower roller support portions  80 ,  82  in each pair are spaced apart from each other so that a roller  86  can be mounted between the respective upper and lower roller support portions  80 ,  82 . The pairs of upper and lower roller support portions  80 ,  82  are separated from each other around the roller hub  74  to define openings therebetween, see FIG.  2 . 
     Each roller  86  has a cylindrical central portion  88  with an upper bearing end  90  at the upper end thereof and a lower bearing end  92  at the lower end thereof. The upper bearing end  90  is mounted within a slot  94  provided within the upper roller support portion  80  and the lower bearing end  92  is mounted within a slot  96  in the lower roller support portion  82  such that each roller  86  is rotatable with respect to its respective upper and lower roller support portions  80 ,  82 . 
     The upper and lower bearing ends  90 ,  92  and an outer shell which forms the cylindrical central portion  88  of each roller  86  are formed from brass, steel, carbide, bronze, stainless steel, or other suitable material. A layer of suitable material, such as urethane, TEFLON®, UIIMW plastic, hard chrome plating, or other suitable material, may be coated on the exterior of the cylindrical central shell to control wear on the rollers  86  during repeated use. The cylindrical central portion  88  is filled with lead to weight each roller  86  so that the rollers  86  will move towards and may press against the lower portion  50  of the stator ring  46  as a result of centrifugal force as the roller assembly  40  is rotated by the agitator shaft  28  relative to the stator assembly  38 . 
     Each upper and lower roller support portion  80 ,  82  is mounted to the roller hub  74  by a pair of screws  98 . The upper and lower roller support portions  80 ,  82  can be pivoted to a desired angle relative to the roller hub  74  and then fixed into the desired place by welds. The angle at which the upper and lower roller support portions  80 ,  82  can be pivoted relative to the roller hub  84  is limited by the engagement of the opposite inner ends of the upper and lower roller support portions  80 ,  82  with the exterior surface of the roller hub  74 . As shown in FIG. 2, the pair of upper and lower roller support portions  80 ,  82  are secured at various angles relative to the roller hub  74 . This allows for the ability for the rollers  86  and the stator ring  46  to be wedged against each other for substantially more force than what centrifugal force can provide. Depending on the angle at which the upper and lower roller support portions  80 ,  82  and the roller  86  are positioned relative to the roller hub  74 , the roller  86  may move radially outwardly from the roller hub  74 . 
     Now that the specifics of the structure of the roller-stator assembly  20  of FIGS. 2-4 has been described, the method of using the roller-stator assembly  20  for grinding slurry, a liquid medium having solids suspended therein, is described. 
     The roller-stator assembly  20  is lowered into the mixing vessel  34 . The agitator shaft  28  is rotated by the motor drive assembly  26  which rotates the attached roller hub  74 , the snubber  76  and the pairs of upper and lower roller support portions  80 ,  82 . Slurry flows into the roller-stator assembly  20  by entering through the upper end of the flared upper portion  48  of the stator ring  46  and downwardly through the openings between the upper roller support portions  80 . The rollers  86  advance outwardly from the agitator shaft  28  as a result of centrifugal force and roll over a wet film of suspended solids to grind the solids within the slurry. Excess slurry flows downwardly through the openings between the pairs of upper and lower roller support portions  80 ,  82  and through the openings  64  in the stator ring plate  56 . The excess slurry then flows over the upper surface of the deflector  66 , flows upwardly through the mixing vessel  34  and back for another pass through the roller-stator assembly  20  until the desired viscosity/rheology is obtained. 
     The viscosity/rheology of the slurry may cause the rollers  86  to be spaced from the inner wall of the lower portion  50  of the stator ring  46 . The slots  94 ,  96  in the upper and lower roller support portions  80 ,  82  of each pair permits the respective roller  86  to move towards or away from the inner wall of the stator ring  46 . In addition, the bearing ends  90 ,  92  and the coating on the rollers  86  will wear over time during use. The slots  94 ,  96  allow for movement of the rollers  86  as the rollers  86  wear. 
     Attention is now invited to the second embodiment of the roller-stator assembly  20   a  shown in FIGS. 5 and 6. The roller-stator assembly  20   a  is identical in construction to the roller-stator assembly  20  shown in FIGS. 2-4 except for the differences described herein. 
     The lower stator support plate  44   a  has an upper portion  100  which is horizontal and a lower portion  102  which depends therefrom and has an inner wall which flares inwardly towards the agitator shaft  28 . 
     The stator ring plate  56   a  which has an annular spacer plate  104  mounted thereon is attached to and spaced from the lower stator support plate  44   a  by a plurality of spaced-apart elongated screws  106 . The upper portion  58   a  of the stator ring plate  56   a  is connected to the lower portion  102  of the lower stator support plate  44   a  by the elongated screws  106  such that the screws  106  extend though passageways in the stator ring plate  56   a  and through the spacer member  104 , and into a passageway in the lower portion  102  of the lower stator support plate  44   a.    
     The stator ring  46   a  is mounted between the lower portion  102  of the lower stator support plate  44   a  and the stator ring plate  56   a , and surrounds the agitator shaft  28 . The stator ring  46   a  includes an annular central wall portion  108  which has an upper annular ring portion  110  attached thereto at an upper end thereof, and a lower annular ring portion  112  attached thereto at a lower end thereof by suitable means, such as welding. The inner wall of the central wall portion  108  is vertical. The spacer member  104  also forms part of the stator ring  46   a . The upper and lower annular rings  110 ,  112  have a width which is less than the width of the central wall portion  108  and are attached to the outer half of the central wall portion  108 . The upper ring portion  110  is attached to the lower portion  102  of the lower stator support plate  44   a  by suitable means, such as a plurality of pins  114 . The lower ring portion  112  is attached to the stator ring plate  56   a  by suitable means, such as a plurality of pins (not shown). The components forming the stator ring  46   a  are preferably formed from heavy wall steel tubing or stainless steel tubing. 
     The central wall portion  108  of the stator ring  46   a  is solid. The upper ring portion  110  has a plurality of venturi openings  116  therethrough which are spaced around the circumference thereof. Likewise, the lower ring portion  112  has a plurality of venturi openings  118  therethrough which are spaced around the circumference thereof. The respective upper and lower venturi openings  116 ,  118  are vertically aligned with each other. The function of these venturi openings  116 ,  118  will be described in detail herein. 
     As discussed, the upper and lower rings  110 ,  112  are attached to the outer half of the central wall portion  108 . A plurality of spaced apart pins  120 , which also form a portion of the stator ring  46   a , are mounted between the inner half of the central wall portion  108  and the bottom end of the lower portion  102  of the lower stator support plate  44   a . The pins  120  and the venturi openings  110  alternate around the circumference of the stator ring  46   a  such that the pins  120  do not block the venturi openings  110 , see FIG.  5 . Likewise, a plurality of spaced apart pins  122 , which also form a portion of the stator ring  46   a , are mounted between the inner half of the central wall portion  108  and the upper portion  58   a  of the stator ring plate  56   a . The pins  122  and the venturi openings  112  alternate around the circumference of the stator ring  46   a  such that the pins  122  do not block the venturi openings  112 . 
     Each roller  86   a  of the roller assembly  40   a  has a cylindrical central portion  868   a  with an upper bearing end  90   a  at the upper end thereof and a lower bearing end  92   a  at the lower end thereof. Identical to that of the embodiment shown in FIGS. 2-4, the upper bearing end  90   a  is seated within a slot  94   a  provided within the upper roller support portion  80   a  and the lower bearing end  92   a  is seated within a slot  96   a  in the lower roller support portion  82   a  such that each roller  86   a  is rotatable with respect to its respective upper and lower roller support portions  80   a ,  82   a . As shown in FIG. 5, four rollers  86   a  are provided, such that four pairs of upper and lower roller support portions  80   a ,  82   a  are provided. A plurality of tooth sprockets  124  are provided at the upper end of the cylindrical central portion  88   a  which protrude outwardly therefrom. A plurality of tooth sprockets  126  are provided at the lower end of the cylindrical central portion  88   a  which protrude outwardly therefrom. The upper tooth sprockets  124  engage against the upper pins  120  and the lower tooth sprockets  126  engage against the lower pins  122  as the roller assembly  40   a  rotates relative to the stator assembly  38   a.    
     The upper and lower bearing ends  90   a ,  92   a , the tooth sprockets  124 ,  126 , and an outer shell which forms the cylindrical central portion  88   a  of each roller  86   a  are formed from brass, steel, carbide, bronze, stainless steel, or other suitable material. A layer of suitable material, such as urethane, TEFLON®, UIIMW plastic, hard chrome plating, or other suitable material, may be coated on the exterior of the cylindrical central shell to control wear on the rollers  86  during repeated use. The cylindrical central portion  88   a  is filled with lead to weight each roller  86   a  so that the rollers  86   a  will move towards and may press against the central wall portion  108  of the stator ring  46   a  as a result of centrifugal force as the roller assembly  40   a  is rotated by the agitator shaft  28  relative to the stator assembly  38   a.    
     Now that the specifics of the structure of the roller-stator assembly  20   a  of FIGS. 5 and 6 has been described, the method of using the roller-stator assembly  20   a  for grinding slurry is described. 
     The roller-stator assembly  20   a  is lowered into the mixing vessel  34 . The agitator shaft  28  is rotated which rotates the attached roller hub  74   a , the snubber  76   a  and the pairs of upper and lower roller support portions  80   a ,  82   a . Slurry flows into the roller-stator assembly  20   a  by entering through the flared lower portion  102  of the lower stator support plate  44   a . The slurry flows downwardly through the openings between the upper roller support portions  80   a . The rollers  86   a  advance outwardly from the agitator shaft  28  as a result of centrifugal force and roll over a wet film of suspended solids to grind the solids within the slurry. The upper tooth sprockets  124  engage with the upper pins  120  and the lower tooth sprockets  126  engage with the lower pins  122 , as the roller assembly  40   a  rotates within the stator assembly  38   a . The engagement of the tooth sprockets  124 ,  126  and the pins  120 ,  122  prevents the rollers  86   a  from skidding relative to the inner wall of the stator ring  46   a . Slurry flows outwardly from the stator ring  46   a  through the venturi openings  116 ,  118  in the upper and lower rings  110 ,  112  to promote mixing. Excess slurry flows downwardly through the openings between the lower roller support portions  82   a  and through the openings  64   a  in the stator ring plate  56   a . The excess slurry flows over the upper surface of the deflector  66   a , flows upwardly through the mixing vessel  34  and back for another pass through the roller-stator assembly  20   a  until the desired viscosity/rheology is obtained. 
     The viscosity/rheology of the slurry may cause the rollers  86   a  to be spaced from the inner wall of the stator ring  46   a . The slots  94   a ,  96   a  permits the respective roller  86   a  to move towards or away from the inner wall of the stator ring  46   a . In addition, the tooth sprockets  124 ,  126 , the bearing ends  90   a ,  92   a  and the coating on the rollers  86   a  will wear over time during use. The slots  90   a ,  92   a  allow for movement of the rollers  86   a  as the rollers  86   a  wear during use. 
     Attention is now invited to FIG.  7 . While the roller-stator assembly  20   d  of FIG. 10 is shown mounted to the dispersing apparatus  22 ′ of FIG. 7, it is to be understood that any of the embodiments of the roller-stator  20 ,  20   b ,  20   c ,  20   e  shown in FIGS. 2-3 and  8 - 11  can be mounted on the dispersing apparatus  22 ′ shown in FIG.  7 . The dispersing apparatus  22 ′ shown in FIG. 7 includes a mounting frame  24 ′, a motor drive assembly  26 ′, and an agitator shaft  28 ′ connected to the motor drive assembly  26 ′. The motor drive assembly  26 ′ may include a variable speed motor  30 ′ for driving the agitator shaft  28 ′ through a belt and variable speed pulley arrangement (not shown). 
     As illustrated, the roller-stator assembly  20   d  is connected to a lower end of the agitator shaft  28 ′. The agitator shaft  28 ′ and the roller-stator assembly  20   d  may be lowered into an operating position in an associated mixing tank  34 ′ shown in phantom line in FIG. 7 by means of an associated hydraulic piston (not shown) which also forms part of the disperser apparatus  22 ′. 
     In each embodiment of the roller-stator assembly  20   b ,  20   c ,  20   d ,  20   e , the agitator shaft  28 ′ is connected to the center of the roller-stator assembly  20   b ,  20   c ,  20   d ,  20   e  and defines a central axis of the roller-stator assembly  20   b ,  20   c ,  20   d ,  20   e . The roller-stator assembly  20   b ,  20   c ,  20   d ,  20   e  includes a stator assembly  38   b ,  38   c ,  38   d ,  38   e  connected to and supported by the mounting frame  24 ′ and a roller assembly  40   b ,  40   c ,  40   d ,  40   e  connected to the lower end of and driven by the agitator shaft  28 ′. The stator assembly  38   b ,  38   c ,  38   d ,  38   e  of each roller-stator assembly  20   b ,  20   c ,  20   d ,  20   e  shown in FIGS. 8-11 is identical in construction to the stator assembly  38  shown in FIGS. 2-4 except for the differences described herein. 
     In each of the embodiments shown in FIGS. 8-11, each stator support rod  46   b ,  46   c ,  46   d ,  46   e  includes a lower portion  128  and an upper portion  130  which are telescoped together. The lower and upper portions  128 ,  130  can be extended to lengthen the overall length of the stator support rods  46   b ,  46   c ,  46   d ,  46   e , or can be retracted to shorten the overall length of the stator support rods  46   b ,  46   c ,  46   d ,  46   e . The upper portion  130  of each stator support rod  46   b ,  46   c ,  46   d ,  46   e  is attached to a plate  132  which is connected to a moving means  134 . The telescoping function of the stator support rods  46   b ,  46   c ,  46   d ,  46   e  can be effected by pneumatic operation using a compressed air source  136 , as shown, hydraulic operation using a hydraulic power pack, by a lever from below the machine, or by other suitable means. When telescoped, the stator assembly  38   b ,  38   c ,  38   d ,  38   e  can be completely separated from the respective roller assembly  40   b ,  40   c ,  40   ed    40   e , partially engaged with the respective roller assembly  40   b ,  40   c ,  40   d ,  40   e  such that the respective rollers  86   b ,  86   c ,  86   d ,  86   e  are partially engaged with respective stator ring  46   b ,  46   c ,  46   d ,  46   e , or completely engaged with the respective roller assembly  40   b ,  40   c ,  40   d ,  40   e  such that the respective rollers  86   b ,  86   c ,  86   d ,  86   e  are completely engaged with the respective stator ring  46   b ,  46   c ,  46   d ,  46   e.    
     Attention is now specifically invited to the embodiment of the roller-stator assembly  20   b  shown in FIG.  8 . 
     With regard to the stator assembly  38   b , the inner wall  50   b  of the lower portion of the stator ring  46   b  tapers inwardly relative the central axis of the agitator shaft  28 ′ as it extends downwardly. 
     The roller assembly  38   b  includes a roller hub  74   b  mounted to the bottom end of the agitator shaft  28 ′. The roller hub  74   b  has a central portion  140   b  which has a passageway through the center thereof. The agitator shaft  28 ′ is mounted within the passageway of the central portion  140   b  and the uppermost end of the central portion  140   b  abuts against a shoulder on the agitator shaft  28 ′. The outer wall  142   b  of the central portion  140   b  tapers inwardly relative the central axis of the agitator shaft  28 ′ from its top end to its bottom end. A plurality of pairs of upper roller support portions  80   b  are integrally formed with the central portion  140   b  of the roller hub  74   b  and extend horizontally outwardly from the central portion  140   b  toward the stator ring  46   b . Each upper roller support portion  80   b  has a slot  94   b  therein in which the upper bearing end  90   b  of an associated roller  86   b  is seated. 
     The roller hub  74   b  is seated on a plate  144   b  which has an aperture through the center thereof. The plate  144   b  includes a lower annular portion  146   b  and has a plurality of pairs of lower roller support portions  82   b  which extend horizontally outwardly from the lower annular portion  146   b  toward the stator ring  46   c . The lower annular portion  146   b  extends downwardly into the central aperture provided in the stator ring plate  56   b  of the stator assembly  38   b . The lower annular portion  146   b  can engage the annular bearing  72   b . Each lower roller support portion  82   b  has a slot therethrough in which the lower bearing end  92   b  of an associated roller  86   b  is seated. 
     A screw  78   b  extends through the passageway in the lower annular portion  146   b  and extends into a passageway in the agitator shaft  28 ′ to secure the plate  144   b , the roller hub  74   b  and the agitator shaft  28 ′ together. The roller hub  74   b  is sandwiched and securely held in position between the plate  144   b  and a shoulder on the agitator shaft  28 ′. The head of the screw  78   b  seats against an inner shoulder of the plate  144   b  which protrudes into the central passageway thereof. 
     The upper and lower roller support portions  80   b ,  82   b  are generally planar and have an angled edge along one side thereof, like that of the embodiment of FIGS. 2-4. The upper and lower roller support portions  80   b ,  82   b  are formed in pairs and each pair is spaced apart from each other so that a roller  86   b  can be mounted therebetween. The pairs of upper and lower roller support portions  80   b ,  82   b  are separated from each other around the central portion of the roller hub  74   b  to define openings therebetween. 
     Each roller  86   b  has a central portion  88   b  which tapers inwardly relative to the center of the roller  86   b  from its upper end to its lower end. The upper and lower bearing ends  90   b ,  92   b  of each roller  86   b  are mounted within the slots  94   b ,  96   b  provided within the respective pair of upper and lower roller support portions  80   b ,  82   b  such that the roller  86   b  is rotatable with respect to its respective upper and lower roller support portions  80   b ,  82   b.    
     The upper and lower bearing ends  90   b ,  92   b  and an outer shell which forms the central portion  88   b  of each roller  86   b  are formed from brass, steel, carbide, bronze, stainless steel, or other suitable material. A layer of suitable material, such as urethane, TEFLON®, UIIMW plastic, hard chrome plating, or other suitable material, may be coated on the exterior of the central shell to control wear on the rollers  86   b  during repeated use. The central portion  88   b  is filled with lead to weight each roller  86   b  so that the rollers  86   b  will move towards and may press against the lower portion  50   b  of the stator ring  46   b  as a result of centrifugal force as the roller assembly  40   b  is rotated by the agitator shaft  28 ′ relative to the stator assembly  38   b.    
     Attention is now specifically invited to the embodiment of the roller-stator assembly  20   c  shown in FIG.  9 . This embodiment is identical to the embodiment shown in FIG. 8, except for the differences noted herein. 
     With regard to the stator assembly  38   c , the inner wall of the lower portion  50   c  of the stator ring  46   c  tapers outwardly relative the central axis of the agitator shaft  28 ′ as it extends downwardly. 
     With regard to the roller assembly  40   c , the outer wall  142   c  of the central portion  140   c  tapers inwardly relative to the central axis of the agitator shaft  28 ′ from its top end to its bottom end. The central portion  88   c  of each roller  86   c  tapers outwardly relative to the center of the roller  86   c  from its upper end to its lower end. 
     FIG. 10 is identical in construction to FIG.  8  and FIG. 11 is identical in construction to FIG. 9 except for the construction of the deflector  66   d ,  66   e  in each embodiment. 
     In FIGS. 10 and 11, the deflector  66   d ,  66   e  includes a plurality of vertical fins or vanes  148   d ,  148   e  which extend upwardly from the upper surface thereof to create a dynamic deflector. The vertical fins or vanes  148   d ,  148   e  extend upwardly from the outer edge of the upper surface of the deflector  66   d ,  66   e  and are spaced from each other around the outer edge of the deflector  66   d ,  66   e . The fins or vanes  148   d ,  148   e  create pumping to help in circulating the slurry within the mixing tank  34 ′. The deflector  66 ,  66   a ,  66   b ,  66   c  of FIGS. 2-6,  8  and  9  is a static deflector. 
     In each of the embodiments of FIGS. 8-11, because the amount of contact between the rollers  86   b ,  86   c ,  86   d ,  86   e  and the stator ring  46   b ,  46   c ,  46   d ,  46   e  can be modified, roller to stator dynamic pressure can be increased or decreased as desired. The more contact between the rollers  86   b ,  86   c ,  86   d ,  86   e  and the stator ring  46   b ,  46   c ,  46   d ,  46   e , the more pressure is created which creates additional force. In addition, because of the tapered shape of the rollers  86   b ,  86   c ,  86   d ,  86   e  in each of the embodiments of FIGS. 8-11, the rollers  86   b ,  86   c ,  86   d ,  86   e  will dynamically drive axially or on their own and load a specific wear area. This wear area can be toughened up with suitable bearing material, such as urethane, TEFLON®, UIIMW plastic, hard chrome plating, or other suitable material. 
     While preferred embodiments of the present invention are shown and described, it is envisioned that those skilled in the art may devise various modifications of the present invention without departing from the spirit and scope of the appended claims.