Abstract:
A system for producing a suitable fuel from waste material including a dispersion tank in which a rotating impeller is positioned in the bottom of such tank in close spaced relationship above a stationary plate and the facing surfaces of the impeller and the plate include shear blocks which intermesh to grind solid materials in the tank and disperse the solid materials in a blend stock making a suitable fuel. A cylinder is connected to raise and lower the impeller to control the spacing between the impeller and the plate and thus control the spacing between the shear blocks to control the fineness of the grinding of the waste material. Means is provided for discharging metal from the dispersion tank and means is provided for circulating liquid from the dispersion tank to an accumulation tank and for recirculating the liquid from the accumulation tank to the dispersion tank. Feeding systems are provided for delivering solid waste material to the dispersion tank and include systems for grinding drums containing waste material, expressing waste material from the drums and augering waste material from the drums. The present invention also provide a method of is processing waste material and a blend stock which provides a suitable fuel and includes the steps of grinding the waste material in a tank containing the blend stock with the grinding being in at least part provided by the coaction between a rotating impeller and a stationary plate so that the degree to which the waste material is ground is controlled by controlling the spacing between the plate and the impeller.

Description:
APPLICATION FOR PATENT 
     This application is a continuation of application Ser. No. 08/477,229, filed Jun. 7, 1995, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an improved method and apparatus for the blending of fuel and hazardous chemical solid waste into a pumpable fuel which can be burned in conventional kilns, such as cement kilns, and in industrial furnaces designed for burning liquids. The present invention also provides an improved method and apparatus for the reduction in size of solids, such as tires, and the dispersion of such solids in a blend stock so that it can be readily used as a fuel which obtains heat from the solids and destroys the solid wastes so that they are no longer hazardous. 
     2. General Background 
     Cement kilns have been used to utilize waste materials to supply heat thereto and they function to destroy the liquefied hazardous waste. Cement kilns function as excellent incinerators because they have operating temperatures which exceed 1800° F. and the flame temperature of the primary burner exceeds 3000° F. The residence time of combustion gases inside the kiln far exceed the required two seconds specified by the EPA. Also, the large mass of reactive minerals traveling down the length of the kiln chemically binds with inorganics to provide a stabilizing effect and the turbulent flow of alkaline mineral dust within the combustion gases flowing down the kiln provides excellent scrubbing of the gases before they are discharged to the environment. 
     In my co-pending application Ser. No. 07/841,834, flied Feb. 25, 1992, now U.S. Pat. No. 5,257,586 there is disclosed an improved method and apparatus for feeding solid waste materials to the interior of a cement kiln which has unique systems for the prevention of back-flashing of combustion in the feeding system and a system for delivering the solids to the interior of the rotating drum without interfering with the drum rotation. 
     Prior to the present invention, a mixture of liquid and semi-liquid (sludge) waste material has been delivered to the burner of a kiln as a means of destroying the hazardous waste and obtaining usable heat from such destructive burning. Other efforts have been made to supply such wastes pneumatically as dry and powdered solids into the primary burner of a kiln. These methods greatly limit the types and amounts of solid hazardous wastes which have been burned in kiln burners and industrial furnaces. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved method and apparatus for processing hazardous waste solids and combining such waste solids with a suitable liquid blend stock so the solids are dispersed sufficiently to provide a fluid stream which is readily burnable in a kiln or industrial furnaces. The method involves the feeding of a suitable liquid blend stock to a dispersion tank together with partially reduced solid wastes and therein further reducing the solid wastes to a sufficiently small size and dispersing the wastes in the liquid stock and delivering the resultant stream to an accumulation tank from which the liquid dispersion may be withdrawn and delivered to a preselected burner for the destruction of the dispersed waste solids and for the generation of usable heat from the burning of such liquid dispersion. In addition to the improved means for initial preparation of the waste solids and their delivery to the dispersion tank and the means for removing metal from the waste solids, the dispersion unit includes an impeller and a stationary plate which are positioned in the bottom of the dispersion tank and the impeller rotates with respect to the stationary plate. The facing surfaces of the impeller and plate include interdigitating shear blocks and axial movement between the impeller and plate is provided so that the shear blocks can reduce the solids to smaller and smaller sizes as the impeller and plate near each other. A means is provided for the feeding of a stream of material from above the impeller downwardly through a central opening into the space between the impeller and plate, which is designated the attrition zone, and the stream passes radially outward between the impeller and plate while also being subject to the actions of the shear blocks to reduce the size of the solids. A means is provided to withdraw a stream from the dispersion tank after it has been through the smallest spacing of the impellers to be  ˜  and that stream is delivered to the accumulation tank. A means is also provided to recirculate material from the accumulation tank to the dispersion tank through a suitable pump, a grinding means and a magnetic trap means. The present invention may be used with all forms of solids, such as tires, wood, waste materials which have been encapsulated in metal drums and other waste materials. The dispersion tank and the transfer means both include means for the removal of metal from the system so that it is not fed to the burner. Additionally, the present invention provides improved means for preprocessing solid wastes to be delivered to the dispersion tank of the present invention which maintains the hazardous waste solids in an inert atmosphere to ensure that no hazardous material is free to escape from the system. By utilizing the attrition zone of the present invention, it can disperse solids and semi-solids in a fluid stream as a part of the function of a rotating impeller. 
     An object of the present invention is to provide an improved method of preparing hazardous solid wastes which allows them to be readily burned in kiln or industrial furnaces to yield heat and cause their ultimate destruction. 
     Another object of the present invention is to provide an improved apparatus and method of dispersing hazardous solid wastes in a suitable blend stock so that they may be readily fed to a burner in a kiln or industrial furnace. 
     Still another object of the present invention is to provide an improved method and apparatus for processing hazardous solid waste which reduces the size of the solids to a sufficient degree that they may be dispersed into a stream of blend stock which can readily be fired. 
     A further object of the present invention is to provide an improved method and apparatus for processing hazardous solid waste materials so that they may be readily burned with an efficient and simple method which is cost effective to operate and requires little maintenance. 
     Still another object of the present invention is to provide an improved method and apparatus for reducing the size of solids and dispersing them in a fluid media. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which, like parts are given like reference numerals, and wherein: 
     FIG. 1 is a perspective view of the system of the present invention which includes the dispersion unit and the accumulation tank and the components in the circulation system between the dispersion unit and the accumulation tank. 
     FIG. 1A is a schematic view of the system shown in FIG. 1 which more clearly illustrates the basic connections between the accumulation tank and the dispersion unit; 
     FIG. 2 is a side view of the operating equipment installed in and below the lower end of the dispersion tank with the tank removed for clarity; 
     FIG. 3 is a sectional view of the lower end of the dispersion tank and the equipment contained therein and therebelow; 
     FIG. 4 is a perspective view of the equipment in the lower end of the dispersion tank; 
     FIG. 5 is an exploded view of the dispersion equipment with the stationary plate removed for clarity; 
     FIG. 6 is and exploded view of the impeller and stationary plate to illustrate the interdigitating shear blocks which perform the reduction is size of solids passing through the attrition zone; 
     FIG. 7 is a side view, in partial section, showing the interdigitation of the shear blocks in the attrition zone; 
     FIG. 8 is a perspective view of a drum shredding and feeding system; 
     FIG. 9 is a perspective view of a drum augering and feeding system. 
     FIG. 10 is a perspective view of a drum extrusion and feeding system; 
     FIG. 11 is an elevation system of a bulk feed conveyor for delivering solids to the dispersion unit of the present invention; 
     FIG. 12 is a schematic sketch of another form of magnetic conveyor system to be used for removing metal from the bottom of the dispersion unit; 
     FIG. 13 is an elevation view of an attrition mill for both macerating solids and dispersing them in the fluid stream flowing through the device; 
     FIG. 14 is a perspective view of a rotor wherein the spacing between the teeth bears an inverse relationship to the distance of the teeth from the center of the rotor; 
     FIG. 15 is a perspective view of a stator wherein the spacing between the teeth bears an inverse relationship to the distance of the teeth from the center of the stator; 
     FIG. 16 is a plan view of a pie or wedge-shaped segment of a stator or rotor; 
     FIG. 17 is a perspective view of an alternate method of construction of a stator or a rotor; 
     FIG. 18 is a perspective view of a dispersion and agitation system assembly; 
     FIG. 19 is a cross sectional view of the assembly shown in FIG. 18; 
     FIG. 20 is a cross sectional view of the valve entry system of the dispersion and agitation assembly shown in FIG. 18; 
     FIG. 21 is a internal view of tank wherein the dispersion and agitation system has been installed through the top of the tank; 
     FIG. 22 is a perspective view of the dispersion and agitation system assembly with a portion of the collection ring broken away; 
     FIG. 23 is a side view of the dispersion and agitation system assembly installed in either the side or in the bottom of a tank; 
     FIG. 24 is an elevational view of a reduced size dispersion and agitation system with an upwardly facing opening but without the vane entry system; 
     FIG. 25 is an elevational view of a reduced size dispersion and agitation system with a downwardly facing opening but without the vane entry system; and 
     FIG. 26 is a cross sectional view of the dispersion and agitation system installed fed in a pipeline. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The improved apparatus of the present invention is illustrated partially in FIG. 1 wherein the dispersion unit  10  is shown with the accumulation tank  12  and the elements providing connections therebetween. The feeding of the solid waste materials is more completely illustrated in the other drawings as hereinafter described. Dispersion unit  10  includes tank  14  which includes solids inlet connection  16  in its upper end, recirculated fluid inlet  18  in its upper end and connecting to line  20  and discharge  22  connected into the bottom as hereinafter more completely shown and described and connected to discharge line. Line  20  connects into the lower portion of accumulation tank  12  and through recirculation pump  26  so that fluid in tank  12  can be recirculated to dispersion unit in Line connects to supply pump  28  which is connected through magnetic trap  30  to grinding unit and line  34  leads from grinding unit  32  to the connection  36  on the top of accumulation tank  12 . Blend stock is supplied through inlet  37  in the top of tank  14 . Dispersion tank  14  is supported on legs  38 . 
     FIG. 2 illustrates dispersion unit  10  with tank  14  removed for clarity. Main drive  40  is supported centrally below the center of tank  14  which has conical bottom  42  which, as shown in FIG. 3, is secured to flange  44  on support structure  46 . Stationary plate  48  is supported above flange  44  and cylinder  50  which is supported on support structure  46  and connects to impeller  52 . Thus, cylinder  50  can raise and lower impeller  52  with respect to stationary plate  48  to control the spacing therebetween which is designated the attrition zone 54 . Impeller  52  includes a plurality of vanes  56  on its upper surfaces to cause circulation of the fluid within the lower portion of the tank  14  and function during rotation as hereinafter described. Conical bottom  42  includes downwardly extending cylindrical section  58  and radially extending flat section  60  which connects to flange  44 . Trolley  62  is supported between legs  38  and cylindrical section  58  and is rotated for the purpose hereinafter described by motor  64 . Trolley  62  supports magnets  66  which are positioned immediately under bottom  42  which is of a nonmagnetic material. Perforated plate  68  is secured to the inner conical portion of bottom  42  and terminates a short radial distance outward from the outer edge of stationary plate  48 . Outlet  70  is connected through radial section  60  and line  24  to supply pump  28  wherein it is delivered to accumulation tank  12 . As can be seen from FIG. 4, the iron metal which reaches the bottom of tank  14  is attracted by the rotating magnets  66  and pulled around the bottom  42  until it reaches fence  72  which is secured to the upper surface of the conical portion of bottom  42  as shown and leads to metal discharge  74 . 
     The linear movement of impeller  52  is possible because the upper end of cylinder  50  is secured to the support structure  46  immediately under flange  44  and the rod  50   a  is connected to bracket  50   b  that is secured to fixed cylinder  76 , of the quill assembly  75 , surrounding drive shaft  78 . The quill assembly  75  is axially movable and its movement moves impeller  52  and drive shaft  78 . Drive  40  is connected to drive shaft  78  by spline connection  80  which allows the relative movement between drive shaft and drive  40 . Wear ring  82  is secured to support connection  46  and surrounds the upper end of cylinder  76 . 
     As shown in FIG. 6, the upper side of stationary plate  48  and the lower surface of impeller  52  each include a plurality of shear blocks  84  which are spaced relative to each other so that with rotation of impeller  52  they interdigitate or intermesh. As best seen also from FIG. 6, ports  86  extend through impeller  52   50  that fluid being processed is conducted into attrition zone  54  to flow outward between plate  48  and impeller  52 . Vanes  88  are positioned inwardly of ports  86  so that the rotation of impeller  52  causes the fluids and solids to flow through attrition zone  54 . This flow is best seen in the detail of FIG.  20 . 
     Several different methods of feeding the solids to dispersion unit  10  are illustrated in FIGS. 8 through 11. As hereinafter discussed, these systems include a drum shredding system (FIG.  8 ), a drum angering system (FIG.  9 ), a drum extrusion system (FIG.  10 ), and a bulk feeding system (FIG.  11 ). 
     The drum shredding system shown in FIG. 8 is utilized to prepare whole drums of material for feeding into the dispersion system. It includes drum elevator  90 , having a suitable air lock enclosure  92 , shredding chamber  94 , drum feeding ram  96 , shredders  98 ,isolation gate  100  connecting between the system and the inlet  16  on dispersion tank  14  together with such safety equipment as means for supplying an inert atmosphere, fire protection systems and emergency relief systems. Also, illustrated in FIG. 8 is dispersion unit  10  which includes metal separation and conveyor  102  hereinafter described to deliver the waste and scrap metal to waste hoppers  104 . 
     Drums to be shredded together with the materials which they contain are delivered to the loading platform and moved into the elevator  90  where they are raised upward and then moved into air lock enclosure  92 . When the drums have been moved into air lock enclosure  92  the lock door  106  between elevator  90  and enclosure  92  is closed. After providing an inert atmosphere to enclosure  92 , inner lock door  108  is opened. During the time that the drums are being moved to this point they are closed so that waste material does not escape. After the drums are within the shredding chamber they are engaged by drum feed ram  96  which feeds the drums into the upper shredder  98 . The discharged of shredded material from the upper shredder  98  is fed into the lower shredder  98  for further reduction in size of the drums and the waste material which was originally contained within the drums. It should be noted that multiple shredders can be used in series, in parallel or in any combination of both which produces the desired size of waste material and drum metal. Chute  110  connects the discharge of the lower shredder  98  into inlet connection  16  on dispersion unit  10 . 
     In operation of the drum shredding system, one or more drums are transported by elevator  90  to the level of air lock enclosure  92 . The shredding system outer air lock door  106  opens and a conveyor transports the drum horizontally into the air lock chamber  92 . This time, the inner air lock door  108  remains closed to isolate the air lock chamber  92  from the environment. Once the drum is inside the air lock chamber  92 , the outer air lock door  106  closes and the chamber  92  is automatically purged with inert gas until the resulting oxygen level is well below ignition concentrations. Once this condition has been satisfied, the inner air lock door  108  opens and the drum is conveyed into the shredding chamber  94  where it falls into the upper shredder  98 . The inner air lock door  108  closes and the feed cycle for another drum charge begins. Meanwhile, the feed ram  96  travels down vertically to provide a positive feed of the drum into the upper or primary shredder  98 . It retracts to its home position when hill extension of the ram  96  has occurred. Shredded product leaves the primary shredder and falls into the secondary shredder  98   a  below. The secondary shredder  98   a  is generally equipped with narrower teeth so that the resulting shredded material is further reduced in size. Shredded material leaves the secondary shredder  98   a  and is discharged into the dispersion unit  10 . 
     A drum auger system is illustrated in FIG.  9  and includes drum elevator  112  which receives drums and elevates them to the level of air lock chamber  114  immediately below platform  116 . The air lock chamber  114  is connected to auger chamber  118  which includes a suitable rotating auger  120 . A suitable drum lid remover  122  is provided and drum carriage  124  supports the drums and presents them in a position so that the auger  120  can enter the open top of the drum and auger the material therefrom. The material is discharged through chute  126  into the inlet  16  on dispersion unit  10 . It should be noted that a shredder may be included in connection with chute  126  if needed. The empty drum exits the air lock chamber  114  onto conveyor  128  on platform  116  and is returned by elevator  112  to the lower level for disposal or transportation to a suitable location for reuse. 
     A drum extrusion system is illustrated in FIG.  10  and includes elevator  130  which extends from ground level to a level above platform  132 . Drums elevated in elevator  130  are discharged into airlock chamber  134  and into extrusion chamber  136 . An extruder ram  138  is used to compact the drums between upper and lower platens  140   a  and  140   b,  respectively. It is noted that the end of the drum may be removed or opened in any suitable manner prior to the extrusion step. Extrusion chamber  136  is positioned immediately above chute  142  which may include a shredder and connects to solid waste inlet  16  of dispersion unit  10 . Thus when ram  138  compacts a drum, its contents are forced into chute  142  and the compacted drum is then removed from between platens  140   a  and  140   b  and discharged from the system through air lock chamber  134  and elevator  130  or other suitable means. It is suggested that the compacted drums be washed with an automatic high pressure washing system before being removed from extrusion chamber  136 . 
     A bulk feed system is illustrated in FIG.  11  and includes feed bin  144  which connects to and feeds the lower end of screw conveyor  146 . Screw conveyor  146  elevates the material to the upper end  147  wherein it is discharged through duct  148  and isolation gate  150  into the inlet  16  of dispersion unit  10 . If desired, a shear shredder may be positioned in duct  148 . The bulk feed system allows the feed and processing of material which is not containerized. In general, a totally enclosed screw conveyor  146  or drag conveyor is used to transport bulk material from a feed hopper to the dispersion units. The feed conveyor  146  is variable speed to yield any desired feed rate and the feed hopper  144  is sized to accommodate a tilt hopper load or a track hoe bucket load. It may also contain an isolation gate similar to that used in duct  148  for use when the bulk feed conveyor is not in service. A transition chute  148  routes the extruded material through a shredding device and then into the dispersion unit  10 . Material is washed from the feed conveyor flights and down the transition chute  148  by a flow of blended material from the dispersion system. 
     Alternately, bulk material can be fed to a freestanding bin. After filling, the bulk feed bin is closed, then elevated and discharged into a shredding system configured similar to the drum shredding system shown in FIG.  8 . This approach allows the direct deposit of material from dump trucks and other transport containers directly into the feed system without the need for further manipulation. 
     A modified apparatus for the removal of metal from dispersion tank  14  is illustrated in FIG.  12 . Tank  14  is shown with metal outlet  152  extending therefrom immediately above conical bottom  42 . The magnets  66  are supported on trolleys  62  and rotate under bottom  42  causing the metal particles within tank  14  which settle to the bottom to move around bottom  42  to wiper  154 . Wiper  154  directs the metal toward outlet  152  and removal conveyor  156  which includes magnets  158  in association therewith as shown. Thus, the metal fragments are picked up and discharged through outlet  152  in an upwardly direction. Ducting  160  surrounding outlet  152  extends upwardly to a level above the maximum liquid level to be maintained within dispersion tank  14  and removal conveyor  156  extends into a chamber (not shown) at the upper end of ducting  160  into which the metal fragments are dropped and discharged from dispersion unit  10  through a suitable chute (not shown) to a suitable collection site (not shown). The upward incline of conveyor  156  allows any waste solids other than the metal fragments to flow downwardly into the lower end of tank  14  so that the metal fragments are discharged from the system with only a minimum of the blend stock. 
     It should be noted with reference to FIGS. 1 and 1 a  that valves V are used to control the flow of fluids within the system and may thus be used to control the level of the liquid dispersion in tank  14  and also the flow of such liquid dispersion through the system, such as the recirculation of the liquid dispersion into the dispersion unit  10  for further size reduction of the solid particle size in the liquid dispersion. 
     In operation an organic liquid known as “blend stock” is first pumped into the system to establish a normal operating level in dispersion unit  10  and a minimum operating level in accumulation tank  12 . All pumps are then started to establish a continuous flow from dispersion unit  10  through the grinding unit  32  to accumulation tank  12 . Recirculation pump  26  supplies flow back to dispersion unit  10  from accumulation tank  12 . With this arrangement, material is continuously recirculated through the dispersion system so that many passes can be made through dispersion unit and grinding equipment. Addition of solid waste to the system ultimately leads to the increase in operating level in accumulation tank  ˜   2  since the operating level of dispersion unit is held constant throughout the process. After establishing the recirculation loop, waste material can be continuously fed into inlet  16  of dispersion tank  14 . Dispersion unit  10  separates and removes shredded drum metal, and the remainder of the waste resides within the system until it is reduced sufficiently to meet the required specifications. A batch of blended Rid is completed when accumulation tank  12  is full and the material meets the required specifications. Once the batch nears completion, the feed of waste material is stopped. Material can be recirculated through the dispersion system when attrition zone  54  is automatically closed to a minimum gap cylinder  50 . This insures the finest particle size possible. The system can then be pumped out and the cycle is ready to begin again with the input of new blend stock. The system can also be operated in a continuous mode by constantly removing a side stream from accumulation tank  12  at a rate equal to the input rate of waste and blend stock to the system. 
     Dispersion unit  10  when charged causes impeller  52  to rotate. The impeller drive shaft  78  supports a mechanical seal assembly  162  (FIG. 3) to isolate the contents of dispersion tank  14  from the environment. The mechanical seal assembly  162  further serves to hold the bearing  77  in place in a manner which minimizes shaft length between the bearing  77  and the impeller  52  thus reducing shaft deflection and run-out to an absolute minimum. The mechanical seal assembly  162  and the quill assembly  75  move togeather as a unit. Therefore, the vertical position of the impeller  52  relative to the fixed impeller  48  is variable and controlled by the positioning of the quill assembly  75 . It is this variable displacement which controls the particle size of the solids dispersed. Shredded ferrous metal will be continuously removed from tank  14  through metal discharge  74  or through outlet  152 . The solid waste material will reside within dispersion system until it is properly ground and suspended in the liquid carrier or blend stock. Dispersion unit impeller  52  is believed to grind and disperse material in three ways. First, impeller  52  produces turbulent hydraulic flow patterns within the lower portion of tank  14  which tend to shear material as high velocity fluid leaving the impeller  52  impinges upon solids. Second, the top of impeller  52  is equipped with vanes  56  which induce hydraulic flow and circulation within tank  14 . These vanes  56  also provide coarse grinding through mechanical action against solids which they strike. Finally, the underside of impeller  52  and the upper side of stationary plate  48  include intermeshing shear blocks  84  within attrition zone  54  which provide fine grinding by physically taking in the solids and shearing them against closely spaced shear blocks  84 . Attrition zone  54  is composed of two disks which have a series of shear blocks mounted in circular patterns on each disk. One disk is bolted or in other ways suitably secured to the dispersion tank  14  and held stationary while the other disk is bolted to the underside of impeller  52  and rotates with it. Material enters attrition zone  54  through ports  86  near the center of impeller  52 . Flow into attrition zone  54  is induced by a series of forward sweeping vanes  56   a  mounted on top of impeller  52 . Vanes  56   a  tend to pressurize the inlet to attrition zone  54 . Spacing between inlet vanes  56   a  limits the size of solid particles that are allowed to enter attrition zone  54 . This configuration avoids plugging of attrition zone  54 . Finally, centrifugal forces created by the rotation of impeller  52  prevent larger particles from changing direction and entering between inlet vanes  56   a.  Flow is further induced through attrition zone  54  by the centrifugal force generated by the rotation of impeller  52 . The shear blocks  84  on the impeller  52  actually travel within the circular paths occurring between the shear blocks  84  on the opposed stationary plate  48 . The shear blocks  84  thus intermesh and provide shearing action as the rotating blocks capture material between stationary blocks. Fluid enters attrition zone  54  near the center of impeller  52 , and it exits radially due to the centrifugal forces induced by impeller  52 . As a particle travels radially, is sheared repeatedly. The angular velocity of the shear blocks  84  increases as the particle travels radially so that an increasing finer grind is obtained before the particle exits attrition zone  54 . The intermeshing design also ensures that attrition zone  54  is self-clearing and will not plug. The shear blocks  84  are tapered vertically and impeller height is controlled by the operation of cylinder  50 . With this arrangement, the gap between shear blocks  84  can be controlled to yield any desired particle size. In the event it is found desirable an alternate design utilizing an impeller without the adjustment of the height of the attrition could be used but the particle size will be held constant and no compensation for wear of shear blocks  84  is available as it is with this height adjustment system. Fluid leaving the attrition zone (along the path indicated by arrow F 1  is discharged into an annular collection ring  53  positioned around the discharge perimeter of impeller  52 . The discharge ring assembly  67  contains top plate  68  which has a series of perforations  68   a.  A pump suction nozzle  45  is also located within the bounds of discharge ring assembly  67 . In this way, pump suction is guaranteed to contain only material which has traveled through attrition zone  54 . All excess fluid entering collection ring  53  simply exits into the main stream through the perforations  65   a  in plate  68  (along the path indicated by arrow F 2 ). Material may recirculate through attrition zone  54  many times before finally being captured in pump suction nozzle  45 . Plate  68  and bottom  42  of tank  14  are frusto-conically shaped and adjoining so that material will naturally migrate to impeller  52  which is located at the low point of their partial cones. The dispersion system utilizes equipment that imparts mechanical energy into the processed liquid as heat. As a result, the temperature of the liquid is likely to rise as it is being processed. Excessively high temperatures will overload the emission control system as well as thicken the blended product due to evaporation of blend stock. To avoid this problem, a cooling system is suggested to control the temperature of the blended liquid. A heat exchanger  164  (FIG. 1A) or other suitable means maybe used. Any of the solid feeding system described herein may be used with the improved system of the present invention and should be selected based upon the character of the waste material which is to be processed. Since the waste material being processed is generally hazardous, it is important that such feeding system make provision to isolate the material from the environment and also exclude oxygen from the system to prevent problems with premature combustion of the material. 
     Mill  200  as shown in FIG. 13 is a modified dispersion apparatus and includes inlet  202  into mill housing  204 . Stationary plate  206  is positioned on the interior of housing  204  immediately surrounding the opening of inlet  202  therethrough. Shear blocks  208  are secured to the inner surface  210  of plate  206 . Rotating disc  212  is positioned within housing  204  and has shear blocks  214  positioned on its surface  216  facing the shear blocks  208  on plate  206 . Shear blocks  208  and shear blocks  214  are so positioned to intermesh. Rotating disc  212  is mounted on drive shaft  218  which is rotated by motor  220 . Also, as with the impellers previously described, drive shaft  218  is axially movable to change the spacing between stationary plate  206  and rotating disc  212   50  that the macerating action of shear blocks  208  and  214  causes any solids entering mill  200  to be more finely ground. Hand wheel  222  is connected to worm gear  223  which causes movement of drive shaft  218 . This movement is possible because of the spline coupling  224  connecting drive shaft  218  with motor  220 . Fluids including the finely ground dispersed solids are discharged from housing  204  through discharge  226 . Mill  200  is a modified form of the present invention but is suitable for uses that involve the fine grinding of materials which are delivered thereto in a fluid and the dispersion of the ground materials in the fluid discharged from the mill  200 . 
     FIG. 14 shows an alternate design of the rotor  310  plate. FIG. 15 shows an alternate design of the stator  312  plate. The rotor  310  and stator  312  plates come together to form the attrition zone  360  (FIG.  19 ). Typically, the rotor  310  and stator  312  plates shown in FIGS. 14 and 15 would be used in a disk attrition mill but the principles embodied therein may apply regardless of the particular application For example, the illustrated rotor  310  and stator  312  plates may be used in any dispersant and agitation system where a fluid such as a liquid, or a liquid mixed with another liquid, or a liquid mixed with solids needs to be made into a more homogeneous mixture. 
     FIG. 16 shows that the rotor  310  and stator  312  plates shown in FIGS. 14 and 15 may be formed from a number of identical pie or wedge shaped segment pieces  314 . The pie shaped segment pieces  314  are typically investment cast and then machined to their final dimensions. The individual pie or wedge shaped segment pieces may then be bolted, welded or attached in a suitable manner to a bed plate  315 . Alternatively, as shown in FIG. 17, the rotor  310  and stator  312  attrition plates may be formed by putting together a series of concentric rings or stages  316 , 318 , 320 , 322  which yield the same tooth pattern. 
     The attrition zone shown in FIGS. 3 and 7 is formed by arranging interesting shear blocks or teeth  84  along radial lines which extend from the center of the rotor  52  and stator  48  attrition plates. In the embodiment shown in FIGS. 14 and 15, the shear blocks or teeth  384  on the rotor  310  plate intermesh with sheer blocks or teeth  384  on the stator  312  plate to form shear points  324  (FIG. 16) as each rotating tooth passes a stationary tooth. This arrangement of shear blocks or teeth  384  is effective in reducing the size of solid material, but some solid particles still bypass the shear points  324  and thus are allowed to pass through the attrition zone  360 FIG. 19) between the stator  312  plate and the rotor  310  plate unchanged or not at all reduced in size. Recirculation of some of the same solid material through the attrition zone  360  eventually reduces all particles to approximately the same size. 
     The attrition zone  360 FIG. 19 formed by the rotor  310  plate shown in FIG.  14  and the stator  312  plate shown in FIG. 15 differs from the design shown in FIG. 6 by varying the circumferential spacing  326  between the teeth or shear blocks  384  to control the size of the particles which are allowed to pass between the various stages of the attrition zone  360 . The solid material to be reduced in size enters near the center  328  of the attrition zone  360  FIG.  15  and then passes radially outward until it exits at the outer perimeter  330  of the attrition zone  360 . The shear blocks or teeth  384  on both the rotor  310  and stator  312  plates are arranged in rings or stages  316 ,  318 ,  320 ,  322  which intermesh with each other. This circumferential spacing between the individual shear blocks or teeth  384  in each successive stage of the attrition zone  360  is decreased as the radial distance from the center  328  of the attrition zone  360  increases so that a particular particle cannot pass to the next radial stage or ring without being reduced in size. Therefore, there is an inverse distance relationship between the spacing  326  between the teeth  384  and the distance of the tooth  384  from the center  328  of the attrition zone  360 . It is only by reduction in size that particles are allowed to pass through the circumferential gap between the teeth. For example, the first stage is formed by four flow vanes  332  on the rotor retaining nut  334  (FIG.  14 ). These four flow vanes  332  cut the solid material to a coarse particle size. The spacing  326  between the teeth  384  in the second stage then, for example, cuts the material to a lesser particle size. The spacing  326  between the teeth  384  then incrementally decreases in all subsequent stages radially outward across the rotor  310  and stator  312  plates. This arrangement and array of shear blocks  384  provides for a multiple stage reduction of coarse material to fine material. Such multiple stage reduction of coarse material to fine material allows the unit to process a greater throughput of solid material while providing a predetermined particle size on a single pass through the attrition zone. The number of spaces  326  between teeth  384  increases with each successive stage so that increasingly more shears of solid material occur at each stage. In practice, this arrangement produces an average particle size which is even smaller than the spacing  326  between the shear blocks or teeth  384 . 
     In the preferred embodiment, the teeth  384  on the stator  312  and rotor  310  plates are tapered from their base  336  to their top  338 FIG. 15) so that the gap  326  between the teeth  384  on the stator  312  plate and the gap  326  between the teeth  384  on the rotor  310  plate can be controlled. This means that the spacing  326  between the stator  312  plate and the rotor  310  plate can be varied to yield any particle size desired, even if the desired particle is coarser than the circumferential tooth spacing  326  in the outermost ring  316  (FIG.  17 ). Opening the gap  326  between the shear blocks or teeth  384  simply allows particles to bypass the remaining stages when they reach the size set by the gap  326 . Conversely, closing the gap  326  allows for adjustment of the teeth  384 , one with respect to other, due to wear of the teeth  384 , to keep the dispersion and agitating performance at an optimum level. Optionally, the teeth  384  need not be tapered. If the teeth  384  are not tapered the sides of the teeth  384  are perpendicular to the bed plate  315 . Thus such straight teeth  384  would intermesh with opposing teeth  384  but no means would be available for adjusting the gap  326  between the teeth  384  as is possible with tapered teeth  384 . If cost is a concern it is less expensive to build rotor  310  and stator  312  plates with straight teeth  384  as opposed to tapered teeth  384 . Finally, the symmetrical shape of the attrition zone  360  allows the rotor  310  plate to function in both directions of rotation. Thus, the rotor  310  and stator  312  plates last twice as long because the rotor  310  plate can be run in both clockwise and counterclockwise directions of rotation before the rotor  310  and stator  312  plates or any portion thereof need to be replaced. 
     It has also been found that the front face  340  (FIG. 15) of each tooth  384  on the rotor  310  plate imparts a velocity component to the fluid passing through the attrition zone  360  due to the centrifugal forces generated by the rotating teeth  384 . In this respect the attrition zone  360  acts as a multi-stage centrifugal pump. Specifically, the stationary stages on the stator  312  plate tend to convert the fluid velocity to fluid pressure as the fluid impinges on the faces  340  of the stationary teeth  384  and travels radially outward on to the next stage. The faster the rotor plate  310  is turned, the greater the fluid flow and thus pressure generated. It will also be understood that as a tooth  384  passes in front of a gap  326  between the teeth  384  in a subsequent stage, the flow path for fluid is temporarily closed off. The continual rotation of the rotor  310  plate then temporarily opens up a fluid path. This fluid path is quickly closed as the next tooth  384  approaches the gap  326  between the teeth  384  in the subsequent stage. Thus the fluid flow is continually interrupted. This results in a pulsation component of fluid flow. This pulsation component of fluid flow serves to increase the flow of fluid through the attrition zone  360  and also enables self-cleaning of the rotor  310  and stator  312  plates. 
     It has also been found that the disclosed configuration of the attrition zone  360  with ever decreasing spaces  326  between the shear blocks or teeth  384  does an excellent job of mixing and homogenizing materials even if the liquid material contains no solids. Thus, the high energy shearing action of the fluid has applications in effectively homogenizing liquids, dispersing emmiscible powders in a liquid, and accelerating chemical reactions. 
     The advantage attributed to using the dispersion and agitation system  300  of the present invention with ever decreasing spaces  326  between the teeth  384  lies in its ability to provide multi-stage mixing and grinding in a single work head. This ability to provide multistage mixing and grinding at a single work head increases the size reduction capability as well as the throughput of the work head. FIG.  18  illustrates a complete rotor assembly  350 . As may be seen in FIG. 19 fluid flows into the top  352  of the rotor assembly  350  through entry ports  354  between intake vanes  356 . The intake vanes  356  and entry ports  354  are best shown in FIG.  20 . Fluid continues on through passageways  358  to the attrition zone  360  where it eventually exits and may be recycled back through the rotor assembly  350 . One unique feature of the rotor assembly  350  design is the attrition zone intake vane or ring assembly  370 . In this design the attrition zone  360  is located under the passageways  358 . The intake vane or ring assembly  370  is equipped with individual vanes  356  which induce a fluid flow inside the rotor assembly  350  while simultaneously breaking down coarse solids by striking them. Fluid containing solids is drawn to the intake vanes  356  and routed to the attrition zone  360  at the bottom of the rotor assembly  350 . 
     In the intake vane or ring assembly  370  design illustrated in FIG. 20 the intake ring  362  is raised higher on the rotor assembly  350 . This allows the diameter of the intake vane or ring assembly  370  to be reduced so that it is actually less than the diameter of the attrition zone  360  intake holes  364 . The centrifugal forces acting on the fluid entering the intake vanes or ring assembly  370  is much reduced because of this reduced diameter. Such reduction in diameter of the intake vane or ring assembly  370  has allowed the throughput of solid material and fluids through the rotor assembly  350  to increase. Also once solid material has passed through the intake vane or ring assembly  370 , it passes down through passageways  358  in the center of the rotor assembly  350  and then passes radially outward to reach the attrition zone  360  intake holes  364 . This flow path complies with the natural direction that the fluid would follow while inside a rotating rotor assembly. Optional placement of flow vanes  356  inside the rotor assembly  350  actually pressurizes the attrition zone  360  and induces the material to flow more aggressively through the attrition zone  360 . Because of the effective pumping action of the instant attrition zone  360  design, these flow vanes  356  are not always necessary but are particularly suitable in some applications. The position of the individual intake vanes  356  in the intake vane or ring assembly  370  is such that each individual vane  356  faces opposite to the direction of rotation of the rotor  310  plate. The spacing between the individual vanes  356  tends to regulate the size of the particle that can be ingested through the intake vane or ring assembly  370 . Therefore anything that can pass through the space between the individual vanes  356  can easily traverse the passage  358  inside the rotor assembly  350  without tending becoming stuck. The attrition zone  360  between the stator  312  and rotor  310  plates is only fed solids which have been sufficiently sized by the intake vane or ring assembly  370  on the top  352  of the rotor assembly  350 . Since the individual intake vanes  356  face in a backward direction, only very small solids can change direction fast enough to be swept into the entry port  354  between the individual vanes  356  along with the fluid. Large solids are simply rejected because they just will not pass through the intake vane or ring assembly  370 . Also the centrifugal forces created by the rotating rotor assembly  350  tend to propel large solids away from the intake vanes  356  so that this configuration generally will not become clogged. 
     Now that the dispersion and agitation system  300  of the present invention has been described with regard to the internal configuration of its working parts it will be understood by those of ordinary skill in the art that it may be configured in a number of ways. Specifically, the dispersion and agitation system  300  may be driven by a connection to a source of rotational power  380  from the top side  382  of a tank  385  instead of the bottom side  386  of a tank  385 . This is shown in FIG.  21 . Herein the same rotor  350 , assembly and attrition zone are used. As shown in FIG. 22, the embodiment shown in FIG. 21 includes a collection ring  390  surrounding the attrition zone  360 . The top mounting of the dispersion and agitation system  300  reduces the overall cost and makes it possible to adapt a dispersion and agitation system  300  to an existing tank. The design also allows for the adjustment of the attrition zone  360  gap and continuous extraction of process material from the tank. 
     In FIG. 23 the dispersion and agitation system  300  of the present invention is shown mounted in the side  388  or bottom  386  of an existing tank. Note that the features of this embodiment are essentially the same as the unit shown in FIG.  22 . Because of the mounting versatility of tile system shown in FIG. 23, it can be used as a substitute for conventional agitators. It also has the added ability of not only mixing the contents within the tank but also to disbursing any solids which may be in the tank. 
     A still smaller version of the dispersion and agitation system  400  is shown in FIG.  26 . Therein the dispersion and agitation system  400  is mounted directly into a pipe line  420  conveying liquids and/or liquids and solid material. The dispersant and agitation system  400  is oriented vertically so that flow must pass upwardly from the pipe line  420  to reach the attrition zone  360 . This vertical orientation provides the opportunity to position a junk collection chamber  422  directly beneath the attrition zone intake  424 . Such an arrangement allows heavy objects such as nuts, bolts, rocks and the like to drop from the flow stream before they enter the attrition zone  360 . In one embodiment, a magnet can even be positioned in the junk chamber to attract and hold ferrous material. Junk then can easily be removed from the collection chamber through a removable access cover. This pipe line mounted unit features single piece rotor  402  and stator  406  plates as well as a single piece cast housing. 
     Conventional pipeline mounted equipment provides a single-stage reduction of solids. If the solids in the stream are large, then the single-stage must provide a coarse grind to yield the desired throughput. Subsequent finer stages can only be used on streams that contain small solids. A fine-stage used with coarse solids actually results in plugging of the work-head because it cannot reduce the size of the solids fast enough to pass through the fine openings in the stator plate, thus resulting in reduction of the flow through the unit. The attrition mill of the present invention, with ever decreasing spaces between the teeth, overcomes these drawbacks because it can accept coarse solids at a high flow rate and then reduce them to a fine particle size through the use of multiple stages on a single rotor plate. 
     Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modification may be made in the embodiments herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in any limiting sense.