Patent Publication Number: US-2021162617-A1

Title: Station for cutting aa-type, d-type and/or c-type batteries, method for separating and recovering components of said batteries and system for implementing such method

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of plants and methods for the disposal and recovery of constituent components of alkaline-type and zinc-carbon-type batteries. In particular, the present invention relates to a cutting station for cutting AA-type and/or D-type or C-type batteries and to a method for the dry separation and the recovery of the components of said batteries. The invention further relates to a system for implementing such a method. 
     BACKGROUND ART 
     The huge dissemination of portable electric and electronic product requires the availability of discrete sources, i.e. self-standing units, capable of outputting electric current. 
     These discreet current sources mainly consist of primary batteries and secondary batteries, or accumulators. The first work according to an oxide-reduction reaction which occurs between two of their components and generates a transfer of electrons which, appropriately channeled, creates the required flow of current. Secondary batteries are instead rechargeable accumulators (e.g. the very common lithium batteries). 
     While secondary batteries (accumulators) have a relative long life and may be subjected to hundreds of recharging cycles before needing to be replaced, batteries proper (primary batteries) must be eliminated after only one life cycle. Given the extremely very high production volumes and the content of chemical species which are potentially hazardous for the environment, batteries pose considerable disposal problems. 
     Although there are many types of batteries based on different oxide-reduction processes, the vast majority of them (nearly 90% of the market) are of the zinc-carbon and of the alkaline type, which is an evolution of the zinc-carbon battery; in particular, alkaline batteries currently account for about 75-80% of the market, while zinc-carbon batteries account for 10-15%. These batteries are used in applications such as electric torches, toys, electrical instruments and miscellaneous electronics. 
     For both battery types, the generation of the electron flow is determined by a reduction reaction of manganese dioxide (IV), MnO 2 , and concurrent oxidation of the metal zinc ion Zn 2+ . 
     In zinc-carbon batteries, the zinc (anode) forms the base and the cylindrical wall of the casing, while the manganese dioxide is immersed in a gelatinous paste also comprising ammonium chloride and carbon powder. 
     In alkaline batteries, the zinc is instead present in the form of power around an anode consisting of a metal bar; Zn and MnO 2  powders are immersed in a gelatinous paste of potassium hydroxide (KOH), which acts as an electrolyte and from which the name “alkaline” of these batteries derives. 
     The paste present in these batteries is also called “black paste” in the sector. 
     The recovery and recycling of the components of zinc-carbon (hereinafter also indicated as Zn—C) batteries and alkaline batteries is the subject of very many studies and publications. 
     The recycling procedures of the batteries imply a series of operations. 
     Firstly, the batteries must be separated by type. 
     The first separation is of dimensional type and allows a first, very coarse, separation of the batteries according to the chemical component type, because the smaller batteries are not generally of the Zn—C or alkaline type; for example, they may be silver or mercury batteries, although the latter type has been nearly entirely phased out following the introduction of standards in most countries. This first separation may consist of a simple passage on vibrating belts or tables with openings of appropriate sizes increasing along the direction of transport of the batteries. 
     A second separation is more specifically related to the chemical type of the batteries. This type of separation may occur as a function of their density, as described for example in international patent application WO 00/08700 A1. The most common method is however based on X-ray imaging techniques which recognize the structure inside the battery (e.g. the arrangement of the electrodes, which may vary according to the battery type), as described, for example, in patents EP 795919 B1 and EP 1132992 B1; some recycling systems also include a manual separation, performed by human operators, for the batteries that the automated systems cannot safely assign to a specific type. 
     After separating the batteries into groups homogeneous by chemical type, which ensures the presence only of materials composing alkaline or zinc-carbon batteries, the black paste components must be extracted from them. According to the known technique, for the extraction, the batteries are grinded in some cases, or alternatively they may be opened in mechanized cutting stations; then, the particulate obtained from the grinding or the parts obtained by cutting are either washed or immersed in water or in aqueous based solutions, which leads to the dissolution or suspension of the black paste components in the liquid phase. 
     In this step, or immediately afterwards, the components which are not part of the black paste, such as the steel which forms the battery casing or the plastic materials which form the lining or seals thereof, must be separated from the solution. The materials are washed in various manners to detach the black paste residues. 
     The liquid phase thus obtained, containing the black paste components in solution or suspension, must then be subjected to chemical recovery processes of said components, in the same form in which they were present in the black paste or after appropriate chemical transformations, into a more manageable or useful form to be sent to the successive steps of recycling or direct reuse. 
     The main problem encountered with the systems of the prior art is that the mixture of materials obtained after the opening or grinding of the batteries is separated only in very coarse manner, so that the matter which is sent to the chemical recycling treatments is a mixture of unknown components, variable from one process to the other (also within the same plant), and which does not allow an effective chemical treatment as a consequence. For these reasons, nearly all battery recycling processes are pyrometallurgical; this implies high energy and environmental costs (emissions and waste). 
     With respect to grinding, the cutting of the batteries by means of mechanized stations promotes the separation of the black paste from the metal part and from the plastic part, because the cut parts have larger sizes than the grinded products. Typically, the batteries are cut by means of a steel blade which is preventively subjected to specific thermal treatments for its hardness and durability. Such treatments are established as a function of the materials which form the batteries. Specifically, cutting blades are used with straight cutting edge which is developed along a reference direction which, during the step of cutting, is orthogonal to the axis of the battery. 
     However, it has been seen that the use of the blade with straight cutting edge is accompanied by various drawbacks, including the short life of the edge due to the impact against the battery. The possible solution of increasing the thickness of the blade, in order to prolong its durability, is an inadequate solution. Indeed, a localized squashing of the casing of the battery occurs at the impact surface with the blade during the step of cutting. Following such a phenomenon, which becomes more relevant as the thickness of the blade increases, portions of the black paste remain trapped between the folds of the squashed surface. The removal of this portion is particularly difficult and is completed by means of various passages in cleaning tanks, with obvious disadvantages in terms of treatment process costs and time. 
     As far this issue, it is worth noting that in nearly all cases, the methods currently used for separating and recovering the parts which form a battery (black paste, metal part and plastic part) include one or more steps of washing and/or one or more passes in treatment tank. Such methods thus have strong limits in terms of eco-sustainability. 
     According to the conditions shown above, the main task of the present invention is to provide a new station for cutting a battery and a new method for separating and recovering the constituent parts of the battery itself. In the scope of this task, it is a first object of the present invention to provide a cutting station which performs better than the traditional stations in terms of durability and reliability. It is another object to provide a method which allows the recovery of the “black paste” contained in a battery by means of “dry” operative steps, i.e. which do not include the use of washing stations and/or passages in treatment tanks. It is a not last object of the present invention to provide a method which is reliable and easy to implement at competitive costs. 
     SUMMARY OF THE INVENTION 
     The present invention thus relates to a cutting station for cutting cylindrical batteries, i.e. batteries which have a substantially cylindrical body, which develops about a central axis between a first surface and second surface, which is transversal to said central axis. The cutting station comprises a substantially two-dimensional cutting blade, which identifies a cutting plane and a positioning device, which defines a seat for a battery to be cut, so that the central axis of the battery is substantially coplanar with the cutting plane identified by the two-dimensional blade. The cutting station further comprises pushing and moving means which determine a relative motion between the blade and the battery to be cut, along a direction of advancement parallel to the cutting plane. Following such a relative motion, the battery is cut into two halves by the blade. According to the invention, the blade comprises a cutting edge which defines at least one V-shaped notch. Such a notch faces one of the transversal surfaces of the battery when it is housed in the aforesaid seat and during the relative motion determined by the pushing and moving means. In particular, the battery impacts, at least partially, against the V-shaped notch following the relative motion determined by the pushing and moving means. 
     It has been seen that the use of a blade with V-shaped notch is particularly advantageous in production terms. In particular, such a solution increases the durability of the blade, decreasing at the same time the number and frequency of machine stops. At the same time, it has been seen that in the scope of a method for the dry separation of battery components, the cutting principle described above advantageously promotes the successive separation operation of the black paste of the batteries from the corresponding metal casing part which contains it. 
     The present invention also relates to a method for the dry separation of the components of cylindrical type batteries. More precisely, such a method has the purpose of separating the inner black paste from the metal part and from the plastic part present in the structure of the batteries. The method according to the invention is characterized in that it comprises at least the following steps: 
     a) cutting each of the batteries into two halves along a diametrical plane containing the central axis of the battery by means of a blade, the cutting edge of which defines at least one V-shaped notch and so that said notch impacts against a transversal surface of the battery; 
     b) mechanically striking the parts obtained by cutting the batteries so as to detach the black paste from the metal part and/or from the plastic part of the batteries; 
     c) separating, by means of vibration-sieving, the fragments obtained following step b) into a first fraction of fragments having a maximum size lower than a first predetermined value and a second fraction of fragments having a maximum size higher than said first predetermined value; 
     d) separating, by magnetic attraction, at least the first fraction so as to separate the metal material fragments from said black paste. 
     The method according to the invention allows to recover the black paste contained in the batteries without any passage in washing stations, with huge advantages in terms of eco-sustainability. In particular, nearly all the black paste is recovered by means of a relatively low number of steps which can be easily performed at absolutely competitive costs with respect to the traditional processes which include the use of washing stations and/or treatment baths. 
     Finally, the present invention further relates to a system for implementing the method shown above. 
    
    
     
       LIST OF DRAWINGS 
       Further features and advantages of the present invention will become more apparent from the following indicative and thus non-limitative description of a preferred, but not exclusive embodiment of the invention, as shown in the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a possible embodiment of a cutting station of a cylindrical-type battery according to the present invention; 
         FIGS. 2 and 3  respectively are a plan view and a side view of the system of  FIG. 1 ; 
         FIG. 3  is a front view of the device in  FIG. 1 , in a first operative configuration; 
         FIGS. 4 to 8  are views related to possible embodiments of a cutting blade in a cutting station according to the present invention; 
         FIGS. 9 to 12  are views related to the cutting station in  FIG. 1  in a specific operative step of the station itself; 
         FIG. 13  is a further axonometric view of an operating system comprising a cutting station according to the present invention; 
         FIG. 14  is a perspective view of a possible embodiment of a system for separating and recovering the components of an cylindrical-type battery according to the present invention. 
         FIG. 15  is a perspective view of a second possible embodiment of a system for separating and recovering the components of an cylindrical-type battery according to the present invention. 
         FIG. 16  is a perspective view of a third possible embodiment of a system for separating and recovering the components of an cylindrical-type battery according to the present invention. 
     
    
    
     The same reference numbers and letters in the figures refer to the same elements or components. 
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the mentioned figures, the present invention thus relates to a cutting station, generally indicated by reference numeral  1 , for cutting a pelight type and/or a flashlight and/or a R14-type battery  2 . In all cases, a battery of each type has a substantially cylindrical body, which develops about a central axis  100  between a first transversal surface and a second transversal surface opposite to the first transversal surface. Such surfaces are substantially “transversal” to the central axis  100  of the battery  2  and correspond to the surfaces on which the electrodes for the operation of the battery itself are defined. 
     The cutting station  1  comprises a cutting device  50  provided with a blade  5  through which the cutting of the battery  2  is achieved. The blade  5  displays a substantially two-dimensional conformation which identifies a cutting plane  200 . Substantially, the blade  5  develops between two parallel planes, the distance of which corresponds to the thickness S 1  of the blade itself. Given the two-dimensional configuration, such a thickness is thus much lower than the other sizes of the blade. 
     The cutting station  1  further comprises a positioning device  60  which defines a seat  61  for the battery  2 . In particular, the blade  61  is shaped so that the central axis  100  of the battery  2  is substantially coplanar with the cutting plane  200  and one of the two transversal surfaces faces the blade  5 . 
     According to the invention, the cutting station  1  further comprises pushing and moving means  40  which determine a relative motion between the blade  5  and the battery  2  along a direction of advancement  400 , which is substantially parallel to said cutting plane  200 . Such pushing and moving means  40  also provide the force/energy needed to allow the blade  5  to penetrate into the battery  2  i.e. to cut the blade itself. Following such a relative motion, and given the position of the central axis  100  coplanar with the cutting plane  200 , the battery  2  is cut by the blade  5  into two halves  2 A, 2 B along a diametrical plane containing the central axis  100  of the battery  2 . 
     The cutting station  1  according to the invention is characterized in that the blade  5  comprises a cutting edge  51  which includes at least one V-shaped notch  55  which faces one of the transversal surfaces of the battery  2  when it is housed in the seat  61  defined above. In this manner, following the actuation of the pushing and moving means  40 , the battery  2  impacts the blade  5  precisely at the notch  55 , which cuts the battery  2  into two halves  2 A, 2 B (see  FIG. 12 ). More precisely, the stretches  55 A, 55 B of the notch  55  cut the battery  2  over its entire length, measured along the central axis  100 . It has been seen that the V-shape advantageously increases the durability of the blade, i.e. the numbers of batteries which may be cut between two machine stops. In particular, it has been found that up to 2000 batteries can be cut with the same notch  55 . The other sizes of the blade and of the batteries being equal, a blade with straight cutting edge can cut one hundred or so batteries at most. 
       FIGS. 4 to 8  show possible embodiments of the blade  5  according to the invention. In particular, the V-shaped of the notch  55  can be observed. The latter is defined by two cutting stretches  55 A, 55 B, which are inclined by an angle α which substantially represents the opening angle of the notch. The two stretches  55 A, 55 B intersect defining an “innermost” vertex (indicated by X in  FIG. 4 ) and are symmetric with respect to a reference axis  201 . The latter is aligned with the central axis of the battery  2  during the step of cutting. Each of the two stretches  55 A, 55 B of the blade  55  ends at an “outermost” vertex (indicated by Y in  FIG. 4 ) which represents an intersection point with a rectilinear portion of the cutting edge  51  which develops along a reference direction orthogonal to the axis  201 . The shape of the notch  55  is identified by the values of the opening angle α and by its width L, meaning the distance between the two outermost vertexes Y defined above. According to the present invention, the opening angle α is chosen from a range of values comprised between 30° and 80°, while the value of the width L is comprised in a range between 10 and 45 mm. According to another aspect, the thickness S 1  of the blade  5  (indicated in  FIG. 5 ) is comprised in a range between 1 and 4 mm. The blade is preferably made of harmonic steel. 
     In general, the shape of the notch  55  is chosen as a function of the size, i.e. of the dimensions, of the cylindrical-type batteries to be cut. In this regard, a classification of the cylindrical batteries is universally used according to their sizes. Mini batteries are indicated by the letters AAA, and penlight batteries are indicated by the letters AA. R14 batteries are indicated by the letter C and flashlight batteries are indicated by letter D. 
       FIG. 4  shows an embodiment of the blade  5  which has been found to perform particularly well in the cutting of D-type battery blades.  FIGS. 6 and 7  show blades which are found to perform particularly well in the cutting of C-type and AA-type batteries, respectively. Finally,  FIG. 8  shows a blade  5  which is particularly adapted to cutting AAA-type batteries. For each of the embodiments illustrated in  FIGS. 4, 6, 7 and 8  indicated above, the table shows the value of the opening angle α and of the width L of the notch  55 . It is worth noting that for each size indicated in the table, the corresponding values of the opening angle α and of the width L are to be considered preferred, and therefore not exclusive. 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 SIZE 
                 OPENING ANGLE - α [deg°] 
                 Width - L [mm] 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 AAA 
                 38.58 
                 14 
               
               
                   
                 AA 
                 48.46 
                 18 
               
               
                   
                 C 
                 61.93 
                 30 
               
               
                   
                 D 
                 74.47 
                 38 
               
               
                   
                   
               
            
           
         
       
     
     Again according to a preferred embodiment shown in the figures, the edge  51  of the blade  5  comprises a plurality of notches  55 , each of which is V-shaped. Even more preferably, all the notches  55  of said plurality have the same shape in terms of width L and of opening angle α. The notches  55  are arranged at a given distance D, measured as the distance between the innermost vertexes X of two adjacent notches. Advantageously, the presence of multiple notches  55  allows a greater operative versatility. Indeed, after a given number of batteries cut consecutively by means of the first V-shaped notch, the same blade  5  may be positioned in the cutting device  50  so that the second V-shaped notch, different from the first one, is used to cut another number of batteries. 
     According to a preferred embodiment shown in the figures, the cutting device  50  comprises locking means for locking the cutting blade  5  in a fixed position. At the same time, the pushing and moving means  40  move the battery  2  between a first position, in which the battery  2  is in the seat  61  of the positioning device  60 , and a second position having reached which the battery  2  is cut into two halves  2 A, 2 B. Preferably, the cutting station  1  also comprises guiding means for guiding the movement the battery  2  along a direction of advancement which is parallel to the cutting plane  200  defined above and thus parallel to the central axis  100  of the battery  2 . 
     According to a possible embodiment shown in the figures, the cutting device  50  comprises a pair of supporting elements  53 A, 53 B of the blade  5  installed on a base  4  of the cutting station  1 . The supporting elements  53 A, 53 B are distanced and positioned symmetrically with respect to a reference plane  300  which is substantially vertical and parallel to the direction of advancement  400  along which the battery  2  is moved by the pushing and moving means  40 . For each supporting element  53 A, 53 B, the locking means of the blade  5  comprise a corresponding locking element  52 A, 52 B. The latter is fixed in removable manner to the corresponding supporting element  53 A,  53 B and in position distanced from the other locking element. The blade  5  thus remains locked between the supporting elements  53 A, 53 B and the corresponding locking elements  52 A, 52 B. In particular, the blade  5  is arranged so that the V-shaped notch  55  is arranged in the space comprised between the supporting elements  53 A, 53 B and between the corresponding locking elements  52 A, 52 B. In particular, the amplitude of such a space, i.e. the width measured orthogonally to the reference plane  300 , is such as to allow the passage of the battery  2  during the step of cutting it. 
     Again with reference to the solution illustrated in the figures, the pushing and moving means  40  preferably comprise a hydrodynamic actuator  41  installed on the base  4  in a position substantially opposite to the cutting device  50 , in position evaluated with respect to that of the positioning device  60 . The hydrodynamic actuator  41  comprises a rod  42 , the end  42 A of which is configured to act on the battery  2 . In this regard, the end  42 A can act directly on the transversal surface of the battery  2  opposite to that which the blade  5  faces. Alternatively, the end  42 A could act indirectly on such a transversal surface, e.g. providing a pusher element connected to the end  42 A itself and acting directly on the transversal surface. 
     In all cases, the rod  42  can be actuated between the minimum extension position, in which the end  42 A does not interact with the battery  2 , and a maximum extension position, having reached which the battery  2  is cut due to the blade  5 . Instead, the minimum extension condition of the rod  42  is such that the end  42 A does not interact with the battery  2 . The latter condition substantially corresponds to a condition of deactivation of the hydrodynamic actuator  41  and thus to a condition in which the battery  2  to be cut can be loaded into the seat  61  of the positioning device  60 . 
     The travel of the rod  42  between the two conditions defined above (minimum and maximum extension) identifies the direction of advancement  400  of the battery  2  defined above. In particular, following the activation of the hydraulic actuator  41 , the rod  42  moves starting from the minimum extension condition. At a given point, the end of the rod  42  starts pushing the battery  2  towards the blade  5  along the direction of advancement  400 . Such a push continues until the cutting of the battery  2  is completed due to the cutting blade  5 . 
     According to another aspect, the cutting station  1  preferably comprises guiding means of the rod  42 . In the form illustrated in the figures, such means are defined by a wall  46  fixed to the base  4  and interposed between the positioning device  60  and the actuator  41 . Such a wall  46  comprises a through hole crossed by the rod  42  during its travel between the two conditions defined above. Advantageously, such a solution contributes to avoiding lateral bending of the rod  42  due to the load which is generated on the rod itself during the cutting effort. 
     According to a further aspect, the guiding station comprises guiding means of the battery  2  to guide it along the direction of advancement  400 , between the first position and the second position. Such means have the purpose of maintaining the central axis  100  of the battery  2  in position coplanar with the cutting plane  200  during the step of cutting the battery itself. In a preferred embodiment shown in the figures, such guiding means comprise a chamber  70  defined by a lower half-shell  71  installed on the base  4  and by an upper half-shell  72  fixed to the lower half-shell  71  by means of removable fixing means. Following their union, the two half-shells  71 ,  72  configure a cylindrical passage, the axis of which is aligned with that of the battery  2  thus remaining coplanar with the cutting plane  200  identified by the blade  5 . Advantageously, the two half-shells  71 , 72  maintain such a coplanar condition during the step of cutting so as to ensure the cutting along the diametrical plane. 
     According to a further aspect shown in the figures, the cutting station  1  is preferably provided also with a loading device  80  for automatically loading/positioning the battery  2  in the seat  61  of the positioning device  60 . The figures show a possible embodiment of such a loading device  80  which loads according to a substantially “revolver” principle. In particular, the loading device  80  comprises a belt element  81  installed between two pulleys  82 A, 82 B supported by a supporting frame (not shown in the figures). A first one  82 A of these pulleys is a drive pulley because it is actuated by a motor, preferably electric. The other pulley  82 B is only used for transmission of the belt  81 . On the latter, a plurality of battery-holder elements  85  are arranged each of which defines a seat  86  in which a battery  2  can be positioned so that its axis remains parallel to that of rotation of the pulleys  82 A, 82 B. A battery  2  intended to be cut by the blade  5  is loaded into each seat  86 . The battery  2  may be loaded manually or alternatively automatically, exploiting for example a conveyor belt (not shown) as conveying and loading element. 
     The loading device  80  is positioned so that the axis of the pulleys is parallel to the direction of advancement  200  and so that one of the pulleys is arranged near the loading device  60  of the cutting station  1 . Following the rotation of the belt  81 , the battery  2  housed in a seat  86  of one battery-holder element  85  reaches an unloading end of the loading device  80 . At each unloading end, the rotation of the battery-holder element  85 , determined by the curvature of the belt  81 , determines the release of the battery  2  from the seat  86 . The belt  81  is arranged so that the battery  2 , exiting from the seat  86  of the belt  81 , is positioned autonomously inside the seat  61  configured by the positioning device  60 . 
       FIGS. 9 to 12  show the operating principle of the cutting station  1  shown in the figures. In particular,  FIG. 9  shows the station during the step of automatically loading the battery  2 . In the condition of  FIG. 9 , the battery  2  is still housed in the seat  86  of a corresponding battery-holder element  85  of the battery  81 . 
     In the condition shown in  FIG. 10 , the battery  2  is positioned in the seat  61  of the positioning device  60  and its central axis  100  is coplanar with the cutting plane  200 . Substantially, the battery  2  is ready to be pushed, by the action of the hydraulic actuator  41 , against the blade  5 . 
       FIG. 11  refers to the step of cutting, i.e. in which the battery  2  is pushed against the blade  5  by means of the rod  42  of the hydraulic actuator  41 . In particular, during its travel along the direction of advancement  400  and during the entire step of cutting, the battery  2  remains, due to the guiding chamber  70 , a position such that the central axis  100  remains coplanar with the cutting plane  200  of the blade  2 . In this manner, at the end of the cut, the battery  2  is split into two halves  2 A,  2 B, as apparent from the enlargement shown in  FIG. 12 . In this regard, in the condition in  FIG. 12 , the rod  42  has reached it maximum extension condition which substantially coincides with the completion of the step of cutting. 
     The present invention also refers to the method for the dry separation of the components of AA-type batteries  1 . In particular, the purpose of such a method is to separate the black paste, inside the batteries, from the metal part, forming the casing of the batteries themselves, and from any plastic materials which form linings or seals of the batteries.  FIG. 14  diagrammatically shows a plant according to the invention which allows the implementation of such a method. 
     In detail, the method according to the invention comprises a first step which envisage of cutting each battery  2  in two halves  2 A, 2 B along a diametrical plane containing the central axis  100  of the battery itself, in particular the cutting of the battery  2  is preferably performed by means of a blade  5 , which identifies a cutting plane  200  and which is provided with a V-shaped notch. In particular, according to a principle already explained above, each battery  2  is cut by generating a relative motion between the battery  2  and the blade  5 , so that the central axis  100  of the battery  2  remains coplanar with the cutting plane  200  and so that the battery  2  impacts against the blade  5  at the V-shaped notch  55 . Preferably, according to a known solution, the step of cutting is preceded by a first preliminary step of dimensionally separating the batteries and by a second preliminary step of separating (following said first step) in which the batteries are separated as a function of their chemical structure. 
     The separating method of the components according to the invention comprises a second step, following the first, which includes mechanically striking the two halves  2 A, 2 B of each battery  2  so as to promote the detachment of the black paste from the metal part forming the metal casing defining the battery itself. 
     Such a second step may be advantageously achieved inside a disaggregation unit  110 , a preferred embodiment of which is shown in  FIG. 13 . Specifically, the disaggregation unit  110  comprises a casing defined by a base  111  from which a side containing wall  112  develops so as to generate a volume closed on top, i.e. in position opposite to the base  111 , by a lid  113 . The latter defines an opening  114  through which the halves  2 A, 2 B of the previously cut battery  2  are loaded. As diagrammatically shown in  FIG. 14 , halves  2 A, 2 B deriving from batteries of different size (e.g. AA, AAA, C and D type), but having the same chemical components of the black paste, except for the different ratio by weight of steel, may be introduced into the disaggregation unit  110 . The disaggregation unit  110  comprises a central pin  116  which emerges internally. One or more disaggregation chains  117  made of metal material are connected to such a central pin  116 . The disaggregation unit  110  is further provided with a motor assembly  118  connected to the central pin  116  to rotate it together with the chain or chains  117 . Due to their rotation, in a few seconds the chains  117  strike the cut batteries determining the detachment of the black paste in a substantially granular form. Preferably, the disaggregation unit  110  also comprises an unloading section  115  of the material struck and disaggregated by means of the chains  117 . 
     Even more preferably, the disaggregation unit  110  is provided with closing means  119  of said unloading section. Such closing means  119  are activated during the rotation of the chains  117  and then deactivated at the end of said rotation to promote the evacuation of the fragments which are generated. 
     In this regard, the fragments generated in this second step may be structurally homogeneous, i.e. consisting of a single component (black paste, metal or plastic) or heterogeneous, i.e. consisting of multiple components (e.g. black paste combined with metal and/or with plastic). In all cases, such fragments have different sizes. The method according to the invention includes a third step which consists in separating, by means of vibration-sieving, the fragments according to their size. In particular, during such a third step, the fragments are separated at least into a first fraction F 1  and at least into a second fraction F 2 , wherein such fragments have a maximum size which is respectively higher and lower than a predetermined value. Preferably, such a predetermined value is approximately 1 mm. 
     The separation into two fractions is preferably performed in a vibration-sieving station  120  comprising at least first sieving means comprising a first vibrating sieve defining openings of amplitude corresponding to said predetermined value. The first fraction F 1  will consist of fragments which cross the first sieve, while the second fraction F 2  will consist of fragments which remain over said sieve. By choosing a predetermined value, in the order of 1 mm or a few millimeters, the first fraction F 1  will consist mainly of black paste granules. In such a first fraction F 1  there may also be small fragments of metal and plastic. 
     The method according to the invention includes at least a fourth step consisting in the step of magnetically separating the first fraction F 1 , i.e. separating, by magnetic attraction, the metal part PM from the black paste BP. The latter may thus be collected and then subjected to a chemical treatment in order to retrieve its constituent components. At the same time, the metal part PM can be collected and reused or in all cases disposed of independently from the black paste BP. 
     The step of magnetically separating may be performed in a magnetic separation unit  125  (or magnetic separator  125 ) comprising magnetic means adapted to attract the fragments of the metal part related to the casing and/or to the electrodes of the batteries. 
     In the black paste separated by means of the magnetic separation  125  there may be small fragments of plastic which can be disposed of in the field of the chemical treatment indicated above. Advantageously, due to the step of vibration-sieving, due to the different density, the large size plastic fragments tend to collect over the vibrating sieve in a different position from the metal fragments and/or the heterogeneous fragments having size higher than the predetermined value in all cases. So, the larger size plastic fragments may be advantageously collected and separated from the second fraction F 2 . The plastic part (indicated by PP) may be thus recovered and recycled in one of the many known processes adapted for the purpose. 
     The second fraction F 2  of fragments, mainly consisting of metal fragments, may also undergo a step of magnetic separation or alternatively be disposed of, e.g. in a foundry or more generally in the field of a fusion process in which the presence of elements such as zinc-carbon-manganese is acceptable. 
     Alternatively, the second fraction F 2  may undergo further steps of dry treatment. For example, according to a possible embodiment of the method diagrammatically illustrated in  FIG. 15 , a step of crushing the second fraction F 2  is included having the purpose of detaching the metal fragments from the hardened black paste on them. Preferably, such a crushing is made in a crushing unit  130  (or crushing mill  130 ) as indicated in the system diagrammatically shown in  FIG. 15 . In addition to the detachment of the black paste from the metal part, the crushing determines, at least in part, an advantageous reduction in size of the fragments. 
     In this variant, the product deriving from the crushing is subjected to a further step of vibration-sieving. This crushing product is broken down into a further first fraction F 1 * and into a further second fraction F 2 *, the fragments of which have a diameter lower and higher than the first predetermined value, respectively. Said further fraction F 1 * is then subjected to the step of magnetic separation according to that shown above for the first fraction F 1  defined to comment  FIG. 14 . 
     The second fraction F 2 *, obtained by means of the second passage in the vibration sieve  120 , will mainly consist of metal fragments which may be possibly separated by means of the further step of magnetic separation. The metal fragments may then be reused, e.g. in the field of a metal casting process. Alternatively, at the outlet of the vibration-sieving station  120 , the second fraction F 2 * may be reused directly, e.g. in a foundry for the production of manganese steel, without the further step of magnetic separation indicated above. 
     Also in this case, in the field of vibration-sieving of the crushing products in the crushing mill  130 , a plastic part PP, separated from the second fraction F 2 * indicated above, may collect over the sieve of the vibration-sieving  120  and can thus be recovered and recycled. With reference to  FIG. 16 , according to a preferred embodiment of the method according to the invention, the step of vibration-sieving is performed so as to separate the fragments into a first fraction F 1 , into a second fraction F 2  and into a third fraction F 3 . In the first fraction, the maximum size of the fragments is lower than a first predetermined value, in the second fraction F 2  is higher than said first predetermined value and lower than a second predetermined value, and in the third fraction F 3  the maximum size of the fragments is higher than the second predetermined value. Even more preferably, the first predetermined value is about 1 mm and wherein said second predetermined value is about 5 mm. 
     In this case, in order to obtain the three fractions F 1 , F 2 , F 3  which are dimensionally homogeneous, the vibration-sieving station  120  comprises at least a first vibrating sieve, which defines openings of size corresponding respectively to the first predetermined value, and at least a second vibrating sieve, which defines opening of size corresponding to the second predetermined value. The third fraction F 3  of fragments (having maximum size higher than said second predetermined value) is defined by the fragments of the second vibrating sieve which were not sieved. 
     The first fraction F 1  and the second fraction F 2  are processed according to the same methods described above with reference to  FIG. 15 , to which reference is made. Substantially, the first fraction F 1  is subjected to magnetic separation, while the second fraction F 2  is crushed and then the respective crushing products are subjected to a successive vibration-sieving. The latter step determines the separation into two fractions F 1 *-F 2 *, not indicated in  FIG. 16  only for the sake of clarity. 
     The third fraction F 3  will mainly consist of metal fragments, the maximum size of which is higher than the second predetermined value. However, such a third fraction F 3  may also comprise heterogeneous elements made of plastic and hardened black paste, i.e. in the form of clumps. Preferably, the third fraction F 3  is magnetically separated in order to separate the fragments of the mixed part PM consisting of homogeneous fragments of plastic or hardened black paste or of heterogeneous fragments consisting of black paste and plastic. 
     Such a mixed part PM is then subjected to the same steps of treating provided for the second fraction F 2 . More precisely, the mixed part PM undergoes a step of crushing in the crushing station  130  the main purpose of which is to crush the black paste clumps. The products of such a crushing are sent directly to the vibration-sieving station  120 . Alternatively, the crushed products could be sent firstly to the disaggregation station  110  and only later to the vibrating sieving station  120 . The preventive passage in the disaggregation station  110  further promotes the separation of the fragments of black paste from those of plastic material. 
     The passage of the crushed products in the vibration-sieving station allows to collect a further plastic part PP consisting of plastic fragments of maximum size higher than the second predetermined value. At the same time, such a passage determines at least one further first fraction F 1 - 3  and at least a second fraction F 2 - 3  of fragments having a maximum size lower and higher than the first predetermined value. Also in this case, the first fraction F 1 - 3  and/or the second fraction F 2 - 3  deriving from the second passage in the vibration-sieving station  120  may be subjected to a further step of magnetic separation to separate the metal part PM from the black paste BP. Alternatively, the second fraction F 2 - 3  could be directly recycled. 
     So, the present invention further relates to a system for implementing the method shown above. Such a system further comprises at least one cutting station  1 , preferably having the peculiarities described above, a disaggregation station  110 , operatively downstream of the cutting station  1 , a vibrating sieving station  120  and at least one magnetic separation station  125 . According to a preferred embodiment, the system further comprises a grinding station  130  with the purposes described above.