Abstract:
A comminuting device includes a comminuting chamber which has a bottom wall and a circumferential wall which extends upwards from the bottom wall. The device also includes a rotatably driven drive shaft which extends essentially orthogonal to the bottom wall, and at least one comminuting element which is disposed next to the bottom wall. This at least one comminuting element can be made to perform a rotary movement about the drive shaft by the drive shaft. A plurality of additional comminuting elements which can be made to perform a rotary or revolving movement about the drive shaft ( 22 ) by means of the drive shaft are arranged above the at least one comminuting element comminuting element disposed next to the bottom wall.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of International Patent Application No. PCT/DE2003/009484 filed Aug. 27, 2003, which claims priority to German Patent Application No. 102 39 820.8 filed Aug. 29, 2002, both of which applications are hereby incorporated by reference in their entireties herein. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to devices for comminuting. In particular the invention relates to a device, which includes a comminution chamber having a bottom wall and a circumferential wall projecting upward from the bottom wall, and which is additionally provided with a rotational drive shaft extending essentially orthogonal to the bottom wall and with at least one comminution element arranged neighboring to the bottom wall and capable of being set in revolving motion about the drive shaft by the drive shaft  
       BACKGROUND OF THE INVENTION  
       [0003]     Such comminuting devices are increasingly being employed in the recovery of raw materials. In particular, this may involve composite materials such as occur for example in the preparation for recycling of electric and electronic appliances or components, recycling monomaterials of ferrous metals, non-ferrous metals, synthetics or wood, fractions from other preceding coarse comminution processes in the recycling industry, or slags from processes of combustion.  
         [0004]     A generic comminuting device is disclosed for example in EP 0,606,891 B1. This comminuting device includes a comminution chamber in which a rotor with vertical shaft is arranged. To this vertical shaft, immediately neighboring upon the bottom wall of the comminution chamber, two chains are attached as comminution elements. The comminution chamber is charged with material to be comminuted through an opening provided in the vicinity of its ceiling. When the material has been comminuted to the desired extent, a trap arranged in the circumferential wall of the comminution chamber near the bottom wall is opened to discharge the comminuted material. A disadvantage of this known comminuting device is that the material to be comminuted can only be comminuted batchwise, i.e. that the process of comminution is discontinuous.  
         [0005]     Consideration is now being given to ways of improving comminuting devices and process. In particular, attention is directed to comminuting devices and processes that can be operated continuously.  
       SUMMARY OF THE INVENTION  
       [0006]     A comminuting device which can be operated continuously is provided. The device includes a comminution element neighboring upon the bottom wall, and a plurality of additional comminution elements that are capable of being set in revolving motion about the drive shaft by said shaft. This configuration ensures that the material to be comminuted that is charged in the comminution chamber is multiply exposed to the impact of the blows of the comminution elements before it arrives at the bottom of the comminution chamber. Thus, the material to be comminuted cannot simply fall to the bottom and leave the comminution chamber again through the discharge opening under the very first blow of a comminution element, as is possible in the case of the comminuting device disclosed in EP 0,606,891 B1. Instead, a plurality of blows ensures an adequate comminution of the material to be comminuted before it arrives in the discharge area. Therefore, the material to be comminuted can be charged into the comminution chamber continuously.  
         [0007]     Since the comminuting device according to the invention is preferably also employed for pre-comminution of the material to be comminuted, and the principal or final comminution of the material comminuted by it takes place in a comminuting device distributed by Applicant under the designation “Rotorprallmühle RPMV” [rotor impact mill RPMV]. it is tolerable if occasionally some not adequately comminuted object is discharged from the comminuting device according to the invention. Such an object, because of its size, can be separated in simple manner from the material discharged and returned to the comminuting device for renewed pre-comminution.  
         [0008]     In order in simple manner to prevent the discharge of large objects, however, it is preferred that at least a portion of the circumferential wall be configured as a grating. This grating, which may be made up of a plurality of members preferably extending vertically, and arranged at a predetermined distance from each other, serves as a sieve, determining the size of material discharged from the comminuting device according to the invention. The material discharged from the comminuting device according to the invention is especially suitable as charging material for the “Rotorprallmühle RPMV” if the value of the predetermined distance is about 38 mm. In order to withstand the ‘bombardment’ with material to be comminuted, i.e. in order to diminish wear on the members of the grating, the members may be made of wear-resistant steel or of cast material.  
         [0009]     So that a controlled discharge of the material that has passed through the grating may be assured, the grating may be surrounded by an outer jacket. To prevent wires or similar fine objects from getting stuck in the space between the grating and the outer jacket, it is proposed that the outer jacket have a predetermined minimum distance from the grating, amounting for example to about 200 mm. In the space between the grating and the outer jacket, the comminuted material may drop onto a catch means preferably of funnel-shaped configuration, for comminuted material, which is disposed at the bottom end of the outer jacket. From this catch means (e.g., a funnel-shaped hopper), the comminuted material may then be discharged downward, for example.  
         [0010]     In addition to the circumferential wall, the bottom wall may also be configured as a grating, at least in part. The comminuted material passing through the bottom grating may also be discharged from the comminuting device by way of the funnel-shaped catch means.  
         [0011]     In addition to the discharge by way of the funnel-shaped catch means, an opening openable and closable at will may be provided in the circumferential wall near the bottom wall, i.e. a discharge opening corresponding to the opening in EP 0,606,891 B1. As has already been explained above, this opening, if the comminuting device according to the invention includes neither a grating nor a catch hopper, may be the sole discharge opening of the comminuting device. Alternatively, however, it is possible also to use this opening as additional discharge opening. But in any case, this discharge opening may be used to empty the comminution chamber in event of overloading of the drive or blocking of the drive shaft. For opening and/or closing of the opening at will, a slide valve may be provided, dynamically actuable by means of a hydraulic cylinder. The size of the gap cleared by the slide valve may be used to influence the size of the material discharged or to influence the residence time in the comminution chamber of the material to be comminuted. Control of the size of this gap may be integrated into the over-all process of controlling the comminuting device.  
         [0012]     To facilitate installation and maintenance work on the grating or/and the comminution elements, provision may be made for at least a circumferential segment of the outer jacket to be swingably arranged, preferably about an axis extending essentially vertical, or/and for at least a circumferential segment of the grating to be swingably arranged, preferably about an axis extending essentially vertical, or/and for a swingable circumferential segment of the grating and a swingable circumferential segment of the outer jacket to form a jointly manageable unit. This swingability may be provided by simple design and production techniques if the outer jacket has a polygonal, preferably an octagonal, contour. In the case of an octagonal contour, the comminuting device may for example be provided with a grating in the region of six of the eight sides of the comminuting device, whereas on the other two sides, preferably diametrically opposed to each other, functional parts may be provided, for example the charge opening for charging material to be comminuted and the discharge opening, making possible the complete emptying of the comminution chamber.  
         [0013]     As is known per se from EP 0,606,891 B1, at least one comminution element, preferably the element neighboring to the bottom wall, may be made up of a chain. A comminution chain has the advantage that, when necessary, it can escape upward, diminishing wear on the bottom wall.  
         [0014]     Moreover, however, it is also possible that at least one comminution element may be made up of an impact member. Impact members, compared to impact chains, have the advantage that they strike the material to be comminuted with greater momentum, and therefore comminute it more effectively. In order to make possible an escape of the impact members when necessary and thus keep them from breaking off, provision may also be made for the impact member to be articulately attached to the drive shaft, preferably swingably about an axis extending preferably parallel to the drive shaft.  
         [0015]     If the comminution elements are helically arranged on the drive shaft, and this preferably in such manner that a comminution element closer to the bottom wall is arranged to run ahead of a comminution element more distant from the bottom wall in the direction of revolution about the drive shaft, then the comminution elements working together on the material to be comminuted can exert a force opposed to gravity. This leads to a prolonged residence of the material to be comminuted in the comminution chamber, and therefore to its better comminution. For this purpose, the drive shaft may, for example, be configured as a hexagonal shaft.  
         [0016]     In development of the invention, it is proposed that the comminution elements be arranged on the drive shaft in planes of comminution elements, having a predetermined minimum distance between them, which may, for example, be about 120 mm. Here, the predetermined minimum distance ensures, firstly, that the suspension of the comminution elements on the drive shaft is of sufficiently stable construction, and secondly that even fairly large fragments of the material to be comminuted can move gradually between the comminution elements towards the bottom wall. In this way, it is ensured that all comminution elements can contribute to the comminution and therefore will wear down uniformly.  
         [0017]     If between the free end of at least one of the comminution elements and the circumferential wall a predetermined distance is provided, then this can reduce the risk of a jamming or wedging of the material to be comminuted between the comminution elements and the circumferential wall, with favorable effects on wear of the circumferential wall, especially when this is configured as a grating.  
         [0018]     If at least one annular attachment is provided, projecting inward from the circumferential wall and preferably of funnel-shaped configuration, then the material that falls downward in the existing gap between the free end of the comminution elements and the circumferential wall can be returned to within reach of the comminution elements. Besides, the annular attachment may be employed as protection for the fastening elements, preferably threaded bolts, with which the elements of the grating are fastened to a bent flattened steel member serving as suspension means.  
         [0019]     In manner known per se, a charge opening may be provided in the region of the upper edge of the circumferential wall, for charging material to be comminuted. Such a charge opening may extend from the upper edge of the circumferential wall over a predetermined distance towards the bottom wall.  
         [0020]     In this way, the material to be comminuted may be introduced at least in part laterally into the comminution chamber, reducing the free height to be provided in the region of the comminuting device according to the invention in view of the structural height of the comminuting device itself and the size of the material to be comminuted. As already suggested above, the charge opening is preferably provided in a circumferential region of the comminuting device not configured with a grating.  
         [0021]     In order to be able to prevent the material to be comminuted from being knocked out of the comminution chamber through the charge opening again upon first contact with a comminution element, only one comminution element may be provided in the uppermost plane of comminution elements, and also if desired in at least one additional comminution element plane arranged below. In addition or alternatively, at least the at least one uppermost comminution element may be of shorter configuration than the remaining comminution elements. Finally, a recoil of charged material may also be prevented in that a supply passage preceding the charge opening is of angled configuration.  
         [0022]     In order to be able to secure a stable rotation of the drive shaft despite the plurality of comminution elements, it is proposed that the drive shaft be rotatably mounted both on the bottom wall and on a ceiling wall of the comminution chamber.  
         [0023]     In manner known per se, the drive motor may be connected to the drive shaft by a belt drive. Here, this belt drive may equalize speed fluctuation of the drive shaft due to the impact loading in simple manner, so that these speed fluctuations will not load the drive motor. The speed of the drive shaft may be between about 200 rpm and about 2,000 rpm, preferably between about 500 rpm and about 1,000 rpm.  
         [0024]     Finally, a connection opening may be provided for connection of an exhaust device, preferably in a circumferential region without grating. This connection opening may also be arranged behind an impact wall, so that wires and the like particles whose mass exceeds a predetermined value will not be aspirated, owing to their inertia.  
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0025]     Further features of the invention, its nature, and various advantages will be more apparent from the following detailed description and the accompanying drawings, wherein like reference characters represent like elements throughout, and in which:  
         [0026]      FIG. 1  represents a sectional view of a comminuting device according to the invention, at the line I-I in  FIG. 3 ;  
         [0027]      FIG. 2  represents a sectional view of a comminuting device according to the invention, at the line II-II in  FIG. 3 ;  
         [0028]      FIG. 3  represents a top view of a comminuting device according to the invention; and,  
         [0029]      FIG. 4  shows a graph to illustrate the service possibilities of the comminuting device according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]     The present invention provides comminuting devices and comminuting processes. Features of an exemplary device and process are described herein with reference to  FIGS. 1-4 .  
         [0031]      FIG. 1  shows a comminuting device according to the invention, which is quite generally designated device  10 . It includes a comminution chamber  12  bounded by a circumferential wall  14 , a bottom wall  16  and a ceiling wall  18 . In the neighborhood of the bottom wall  16  and the ceiling wall  18 , bearing locations  20  are provided for a drive shaft  22 , driven by a drive motor  24  by way of a belt drive  26  in the direction of the arrow P (see  FIG. 3 ).  
         [0032]     On the therefore essentially vertical drive shaft  22 , a plurality of comminution elements  28  are arranged in pairs in comminution element planes one above another. Only the two uppermost planes, i.e. comminution element planes next to the ceiling wall  18 , comprise only a single comminution element  28 . The comminution elements of the plane next to the bottom wall  18  are configured as impact chains  28   a , while the remaining comminution elements are configured as impact members  28   b . The impact members  28   b  are suspended in flying/cantilever arrangement on the drive shaft  22 , i.e. swingable about an axis extending essentially parallel to the drive shaft  22 . For the sake of clarity of the representation in  FIG. 1 , this is shown only for the impact member  28   b ′ of the uppermost plane of comminution elements. The comminution element planes have a distance d 1  from each other (see  FIG. 2 ).  
         [0033]     In the representation according to  FIG. 1  at the upper left, the comminution chamber  12  has an entrance  30  for the material to be comminuted. So that this material will not recoil into the entrance  30  immediately upon first contact with the impact members  28   b , each of the uppermost two planes of comminution elements is provided with only one impact member  28   b . In how many planes of comminution elements only one impact member  28   b  is provided depends on how far the entrance  30  extends downward along the height of the circumferential wall  14 . Besides, the impact members  28   b  of the uppermost planes of comminution elements are configured shorter than the remaining impact members. This is indicated in  FIG. 1  only for the uppermost impact member  28   b ′. In principle, however, the impact members  28   b  of several planes of comminution elements may be curtailed, and this preferably with a ‘pine-tree-like’ lengthwise staggering. How many comminution element planes are involved in the curtailment of the impact members depends among other things on how far the entrance  30  extends along the radius of the comminution chamber  12  towards the drive shaft  22 .  
         [0034]     By contact with the rotating impact members  28   b , the material charged through the entrance opening  30  into the comminution chamber  12  is comminuted. Larger pieces here reside in the neighborhood of the entrance  30  until they are broken by the uppermost impact members  28   b  into fragments whose size depends among other things on the distance d, between the comminution element planes, the circumferential offset of the impact members of neighboring comminution element planes and the speed of the drive shaft  22 . Then these fragments move downward by gravity through the various comminution element planes, being further comminuted through the impact effect of the impact members  28   b  and/or the impact chains  28   e.    
         [0035]     Especially small fragments are flung radially outward against the circumferential wall  14  by the impact of the members  28   b . This circumferential wall  14 , as shown in  FIG. 3 , consists of a grating  32  composed of a plurality of grating members  32   a  arranged vertically. The grating members  32   a  have a mutual distance d 2  so that fragments whose dimensions are smaller than the quantity d 2  pass through the gratings  32  and can leave the comminution chamber  12 . In order to ensure an orderly discharge of this comminuted material, the circumferential wall  14  and/or the grating  32  are surrounded by an outer jacket  34  opening at its bottom end  34   a  into a catch hopper  36 . The lower opening  36   a  of the hopper  36  guides the comminuted material out of the comminuting device  10 .  
         [0036]     To prevent excessive stress and hence excessive wear on the grating members  32   a  by the fragments of material to be comminuted, a distance d 3  is provided between the free ends of the impact members  28   b  and the circumferential wall  14  and/or the gratings  32 . Owing to this distance d 3 , which is greater than the distance d 2  of the members  32   a , however, there is the danger that material not yet sufficiently comminuted may bounce off the grating  32  and drop between the grating  32  and the free ends of the impact members  28   b  onto the bottom plate  16 . This would lead to an excessive stress on the impact chains  28   a  and the lowermost impact members  28   b . Therefore, in this intervening space  33 , two funnel-shaped annular attachments  38  are provided, which return material falling down into this space to the region of the impact members  28   b . In this way, a uniform wear of all comminution elements  28  can be ensured.  
         [0037]     If, owing to wrong choice of operating parameters, for example a too rapid supply of the material to be comminuted, too slow a speed of the drive shaft  22 , or the like, some excessive collection of not adequately comminuted material should nevertheless occur in the region of the bottom wall  16 , then this undesired accumulation of material can be thrown out of the comminution chamber  12  through a lateral opening  40 . This lateral opening  40  is closable by means of a trap  42 , openable or closable at will by means of a hydraulic cylinder  44 . A protective casing  46  provides for an orderly ejection of material without risk of danger to operating personnel.  
         [0038]     Finally,  FIG. 1  also shows a connection  48  for an exhaust device  49 , aspirating dust and the like from the comminution chamber  12  and from the annular space  33  between grating  32  and outer jacket  34 .  
         [0039]     As shown in  FIG. 3 , the comminuting device  10  according to the invention, i.e. in particular its outer jacket  34 , comprises an octagonal cross-section. Here the three lower side surfaces of the outer jacket  34  in  FIG. 3  and the circumferential segment of the grating  32  associated with them are combined into a unit  50 , which can be swung away from the rest of the comminuting device  10  about a vertical axis A to afford access to the comminution chamber  12  and in particular to the drive shaft  20  and to the comminution members  28  for maintenance or operating personnel. Furthermore, each of the three side surfaces of the outer jacket  34  comprises a maintenance flap  54 , affording access to the outside of the grating  32  after being swung away from the outer jacket  34 , for example, in order to replace individual grating members  32   a . Similarly, the three upper side surfaces of the outer jacket  34  are combined into a corresponding unit  52  capable of being swung away from the remaining comminuting device  10  about the axis B.  
         [0040]     In the circumferential segments corresponding to the remaining two side surfaces of the outer jacket  34 , the drive motor  24  including the belt drive  26 , the ejection opening  40 , the entrance  30  and the connecting nozzle  48  for the exhaust device  49  are arranged. In these two circumferential segments, the circumferential wall  14  is configured continuously, i.e. without grating.  
         [0041]     In  FIG. 4 , the conception of a comminution plant  60  is represented in the form of a process diagram, to be employed for recovery of raw materials including compound material, from equipment, such as refrigerators, washing machines, television sets, computers, motor vehicle parts or the like.  
         [0042]     In this plant  60 , the comminuting device  10  according to the invention serves for pre-comminution of the material to be comminuted. The final comminution takes place in another comminuting device  62 , for example the comminuting device distributed by Applicant under the designation ‘Rotorprallmühle RPMV.’ Depending on the material to be comminuted in each instance, it may be necessary or advantageous to precede the comminuting device  10  according to the invention with an additional comminuting device  64  for coarse comminution, for example the comminuting device disclosed in EP 0,606,891 B1.  
         [0043]     On Detailed Course of Process  
         [0044]     The material to be comminuted is introduced at  66  into the comminuting device  64  for coarse comminution. The coarsely comminuted material discharged therefrom at  68  is supplied to a screener  70 , which separates light material and discharges it at  72 . The remaining material is supplied to the entrance  30  of the comminuting device  10  according to the invention for pre-comminution. The pre-comminuted material discharged by way of the catch hopper  36  is passed on to another screener  74 , which again separates out light material.  
         [0045]     To prevent clogging and hence blocking of the comminuting device  10 , material not adequately comminuted is ejected through the lateral opening  40  and returned to the entrance  30  by way of the conveyor  41 . If necessary, un-comminuted material may be separated out completely and discharged at  76 .  
         [0046]     Before the material provided by the screener  74  for principal comminution is supplied to the comminuting device  62  at  78  for final comminution, ferromagnetic parts are separated out in a magnetic separator  80  and discharged at  82 .  
         [0047]     The comminuting device  62  may also be operated in partial circulation, i.e. material not sufficiently comminuted may be returned by way of a conveyor  79  to the entrance  78  of the comminution device  62 . Following the principal or final comminution, a further screening takes place in a screener  84  and a further separation of ferromagnetic particles in a magnetic separator  86 , before the remaining finally comminuted material is supplied to a classifying device  88  and a sorting device  90 . If, owing to inadequate physical separation various materials render impossible a classification of certain fractions of the comminuted material, then this unclassifiable fraction may be returned by way of a conveyor  89  to the entrance  78  of the comminuting device  62   
         [0048]     It will be understood that the foregoing is only illustrative of the principles of the invention, and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.