Abstract:
An apparatus for converting unconsolidated medical waste into a non-hazardous medical waste residue, which apparatus has an improved cutter assembly provided by a rotating cutter assembly that has revolving teeth disposed at an oblique angle relative to the path of travel of the revolving teeth and to the stationary cutter assembly to force the waste material between the revolving and fixed teeth. An auger moves the waste material through the housing longitudinally to keep pressure on the opposing fixed and revolving teeth while grinding the material into a reduced particle size to facilitate its disposal or storage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application relates to a new and improved apparatus for processing medical waste, which is an improvement on U.S. Pat. No. 5,673,861 issued Oct. 7, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This application relates to the field of medical waste treatment and disposal. Specifically, this application is for a new and improved apparatus for rendering medical waste non-recognizable by reason of a reaction with a sterilant and non-recognizable by reason of grinding, shredding and cutting the waste. Hospitals and other institutions must dispose of medical waste which is largely composed of infectious materials, including syringes, hypodermic needles, bandages, metal items, and even hospital gowns, sheets and blankets. Because of the diverse nature of the items which are placed in the medical waste for disposal, the apparatus must have the capability of reducing all of the waste to a small enough size for disposal in a manner which makes the medical waste suitable for storage, or other disposition as a non-infectious medical waste residue. The prior art cited in U.S. Pat. No. 5,673,861 generally discloses the background for this invention, which is an improvement over the apparatus disclosed in U.S. Pat. No. 5,673,861. 
     2. Description of the Related Art 
     SUMMARY OF THE INVENTION 
     The present invention provides a new and improved apparatus for converting unconsolidated medical waste into medical waste residue, which is of a reduced unrecognizable size for disposal in a landfill or the like. 
     The waste is cut, shredded and ground by revolving teeth on a rotating shaft which co-acts with fixed teeth in a housing. One or more of the revolving teeth is of special construction and disposition for moving at an oblique angle and in the same plane with respect to the fixed teeth to obtain an increased cutting, shredding, and grinding action on waste between the revolving and fixed teeth. During the mechanical process thus described, the waste is simultaneously revolved and is rendered non-infectious by mixing and reacting with a proprietary stimulant. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a elevation, partly in section illustrating the two-stage apparatus of this invention; 
     FIG. 2 is an end view of the apparatus of FIG. 1 illustrating an auger which may be used for discharging the processed waste from the apparatus; 
     FIG. 3 is an enlarged view of a portion of the apparatus of FIG. 1, showing in more detail the relationship of the teeth in the upper pre-grinded chamber of the apparatus; 
     FIG. 4 is a sectional view taken on line  4 — 4  of FIG. 3 showing the details of the improved apparatus in the upper pre-grinded chamber; 
     FIG. 5 is an enlarged view taken from FIG. 4 showing one of the rotating teeth co-acting with one of the fixed teeth in the apparatus; 
     FIG. 6 is a sectional view of the main grinding chamber which receives the waste from the pre-grinded chamber thereabove for the final processing of the waste; 
     FIG. 7 is a sectional view taken on line  7 — 7  of FIG. 6 which shows the co-acting teeth on the main grinding apparatus of FIG. 6; and 
     FIG. 8 is an enlarged view taken from FIG. 7 which shows the co-acting rotating and fixed teeth of the apparatus in the main grinding chamber. 
    
    
     DETAILED DESCRIPTION OF INVENTION 
     In the drawings, the letter A refers generally to the apparatus of this invention which has a pre-grinding housing  10  in combination with a main grinding housing  12  positioned adjacent thereto. The housing  10  has an inlet  14  into which unconsolidated medical waste can be introduced from any source. A longitudinal shaft  15  extends through the housing  10  and is connected to a drive apparatus  16  such as a heavy duty 60 horsepower electric motor. At cut line  4 — 4 , the shaft  15  has a sleeve  15   a  keyed to the shaft  15  with key  15   e  in key slots  15   f  and  15   g.  The sleeve  15   a  is on the left end of shaft  15 , as seen in FIGS. 1 and 3. Thus, the sleeve  15   a  is secured at the left end of the shaft  15  for rotation therewith by the key  15   c  in the key slots  15   f  and  15   g.  An auger  15   b  is welded to the sleeve  15   a  for rotation with the shaft  15  to feed the unconsolidated medical waste in the housing from right to left as shown in the upper housing  10  in FIG. 1 of the drawings. At the left end of the housing  10 , one or more fixed grinding teeth F are attached to the housing  10  at spaced circumferential positions as best seen in FIG.  4 . The fixed teeth F co-act with one or more revolving teeth R, as will be explained more in detail. The shaft  15  is mounted at each end in suitable bearings  15   c  as will be understood by those skilled in the art. 
     Filtered water is introduced into the housing  10  from a filtered source through a spray  20   a.  Also, a sterilant is supplied from a source  21  and is either sprayed or fed by gravity from a hopper  21  into the housing  10  for contact with the waste material that is introduced into the housing  10  through inlet  14 . The medical waste is forced between the fixed teeth F and revolving teeth R by the auger  15   b  so that it is ground, shredded and/or cut into smaller waste in the housing  10 , as will be more fully explained. The waste from housing  10  is discharged through an intermediate opening  22  to the interior of lower housing  24  of the main grinding apparatus which also has a shaft  25  extending through the housing  24  which is powered by another drive apparatus  26  such as an electric motor of 60 horsepower. The direction of movement of the waste in the housing  24  is thus preferably in reverse or counter to the movement in the housing  10  as can be seen in FIG. 1. A sleeve  25   a  is secured on the shaft  25  by a conventional key and slot arrangement such as key  26  in key slots  26   a  and  26   b  (FIG.  7 ). An auger  25   b  is welded or otherwise affixed to the sleeve  25   a  for accomplishing longitudinal forcing of the waste to co-acting fixed teeth F secured to the housing  12  and revolving teeth R secured on the sleeve  25   a.  The processed waste is preferably discharged from the lower right-hand end of housing  24  at a suitable opening  24   a  (shown in dotted lines) in the lower portion of the housing  24 . Also, preferably the housing  24  is inclined downwardly towards the outlet  24   b  for facilitating the discharge of the processed waste therefrom. The shaft  25  is supported at each end in conventional bearings  25   c.  Also, a suitable framework H or external housing (not shown) is provided to support and preferably enclose the apparatus A. 
     Looking now at FIG. 2, which shows a discharge auger  32  which has a conventional auger blade  32   a  in a cylinder  32   b,  such auger  32  is adapted to receive the discharge of the processed waste from the outlet  24   a  into the lower end  32   c  of auger  32  and such waste is moved or augured upwardly to the discharge outlet  32   d  to deliver the waste to any suitable location for ultimate delivery to a waste site. Alternatively, the auger  32  may be on the right as shown in dot-dash lines  32   f.    
     In FIGS. 4-6, in particular, the improvement is illustrated in enlarged views. As seen in FIG. 4, a plurality of support blocks  30 , preferably four in number, are equally spaced circumferentially on the shaft sleeve  15   a  and are secured thereto by welding or otherwise affixing the inner ends  31  to the sleeve  15   a.  As best seen in FIG. 3, the blocks  30  are preferably arranged in longitudinal rows, and in FIG. 3, four blocks  30  are shown for each row, with abutting edges  30   a  of adjacent blocks engaging each other. Also, preferably, a row of revolving teeth R can be seen in FIG. 3 on each support block, so that the number of teeth R corresponds with the number of fixed teeth F in the housing  10  that are also preferably formed as a unit with blocks  40 , with abutting edges  40   a  between the blocks  40 . The teeth R and F are interfitting with a sufficient radial gap or space between the revolving teeth R and fixed teeth F into which space or gap the waste material is forced for the shredding, grinding and/or cutting of the waste material such as cloth or the like into small particles or pieces for packaging on disposal, as previously explained. 
     As seen in FIGS. 3 and 5, each tooth R is substantially V-shaped at  50  with the generally pointed end  50   x  of each tooth R fitting into, but slightly spaced radially from the substantially V-shaped groove or valley between adjacent fixed teeth F, as will be explained. Likewise, each pointed end  52  of each tooth F fits into, but is slightly spaced radially a selected amount from the groove or valley between adjacent revolving teeth R. 
     Each tooth R, which is preferably one of six formed together in a row as shown in FIG. 3, is removably attached to one of the blocks  30  with several bolts  55  which have threads  55   a  and a larger diameter head  55   b  than the body of bolt  55 . The length of each bar  55   c  (FIG. 3) which has the teeth  50  formed therewith is the same length as each support block  30 , and preferably each bar  55   c  which preferably has six teeth  50  is separately held by the bolts  55  which are threaded into a support block  30  with threads  30   b  in each block  30  (FIG.  5 ). Each bolt  55  passes through a bore hole  55   d  which is enlarged at  55   e  to receive the enlarged bolt head  55   b.    
     In the present invention, rather than having each row of teeth R forming a revolving cutter assembly being positioned parallel to the fixed teeth F, as in U.S. Pat. No. 5,673,861, they are mounted at an oblique angle, as best seen in FIG. 5, and as explained below, so that as the teeth R are revolved relative to the fixed teeth F on the stationary cutter assembly, they force the waste material between the teeth F and R with a shredding, cutting and grinding action which enables the physical structure of waste material such as cloth blankets, sheets, clothes, and the like which are in medical waste to be successfully reduced into a medical residue of small pieces or particles with a minimum of shut-downs. Such result is accomplished without any, or with a minimum of, shut-downs caused by the binding or jamming of the rotation of teeth R by the fibrous material between the teeth R and F, which has been a problem in the past. 
     Also, as has been explained, the sleeve  15   a  has the auger  15   b  welded thereto with each half auger section preferably extending for the same longitudinal distance as the length of one of the supports  30 , as best seen in FIG.  3 . The auger  15   b  functions together with the movable teeth R as they co-act with the fixed teeth to force the waste material forward in the housing  10  and through and between the teeth R and F. 
     The radial space or gap between the revolving teeth R and fixed teeth F as viewed in FIG. 5 may be the same throughout the length of the teeth in FIG. 3 or it may be varied from right to left to increase the size reduction of the waste as it travels to the left as viewed in FIG. 3 to get the initial shredding, cutting and grinding action in the pre-grind chamber or housing  10 , as explained below. Also, the gap between the teeth  50  and  52  (FIG. 5) in the housing  24  is preferably reduced by having each section of teeth R closer to the opposed section of teeth F as the waste is moved from left to right in housing  24 , as explained more fully below. 
     Further, the oblique angle Ø of each tooth R may vary, and it is preferably between about 10° to about 45° degrees from the tooth&#39;s travel path  50   y  to its pointed lower surface  50   x,  so that trailing edge  50   a  of each tooth  50  enters the radial space between two of the adjacent teeth  52   a  as indicated in FIG.  5 . 
     Such travel of each tooth R is thus on a circular path (as viewed in FIG. 5) as each tooth R moves between a pair of the adjacent teeth F, thus creating a powerful biting, pulling and tearing action on the waste which greatly enhances the shredding of cellulose waste material in particular. 
     Each section of teeth F which preferably has six teeth  52  in each block  40  between ends  40   a,  is secured to the housing  10  by bolts  60  which have threads  60   a  that are threaded into threads  52   d.  A seal ring  63  is positioned between the housing and the teeth F. Each revolving section and fixed tooth section is optionally removable from the housing  10  for replacement. The bolt  55  is unthreaded to remove the tooth R from each support block  30  and each bolt  60  is unthreaded to remove it from the housing  10 . 
     Referring now to FIGS. 6-8, the details of the main housing  24  are shown on an enlarged scale, but the part numbers for the housing  24  and parts thereof are generally the same as in FIG.  1 . When the waste material has been ground, shredded and cut by the teeth R being revolved relative to the teeth F, the waste material is fed by the auger  15   b  to the opening  24   a  at the left end of the housing  10 , and then into the main housing  24 , entering at the left end and moving counter-currently or in reverse relative to FIG.  1  through the housing  24  to discharge outlet  24   b.  Except for such opposite direction of movement of the waste, the teeth R and F, and the auger  25   b  are the same and have the same letters and numerals as those in FIGS.  1  and  3 - 5 . 
     The teeth R are preferably made of an alloy with a 58-62 Rockwell hardness with a tungsten carbide surface or other hard surface materials on the outside of the teeth. 
     In the main housing  24 , as particularly shown in FIGS. 6-8, the assembly for receiving the pre-ground waste from the first revolving and fixed teeth in FIG. 1 preferably has decreasing gaps between the teeth along the length of the shaft  25  to further reduce the size of the waste particles. For example, preferably the gap between the teeth on the first revolving and fixed teeth in housing  10  is within the range of about 0.50 inches to 0.75 inches, with the larger gap of 0.75 being at the right end of the teeth F and R, and the smaller gap of 0.50 being at the left portion of the teeth F and R. The gap between the second revolving and fixed teeth R′ and F′ in housing  24  is preferably within the range between about 0.75 inches to about 0.25 inches, with the larger gap of 0.75 being at the left end portion of the teeth R′ and F′ and the smaller gap of 0.25 being at the right portion of the teeth F′ and R′. 
     It should be understood that the gap between the fixed teeth F and the revolving teeth R may be somewhere between the above examples, and likewise, the gap between the fixed teeth F′ and the revolving teeth R′ may also be somewhere between the above examples. 
     The reduced waste residue in housing  24  is finally augured or otherwise transferred to a packaging location or apparatus (not shown) for disposal or storage. 
     The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the details of the illustrated apparatus and construction and method of operation may be made without departing from the spirit of the invention.