METHOD AND APPARATUS FOR TREATING WASTE MATERIAL

Abstract: The present invention relates to a method and an apparatus for treating waste material, which apparatus comprises a conical rotatable rotor (3) placed between stators (1, 2). At least the stators (1, 2) have recesses (9) by means of which the material in the apparatus can be discharged therefrom when the rotor (3) is rotating. The rotor (3) has several openings (8a, 8b) in the axial direction of the apparatus through which openings at least some of the material is arranged to pass. The edges of the recesses (9) and the openings (8a, 8b) of the rotor (3) are sharp in such a manner that the waste material supplied to the apparatus is ground by means of the sharp edges when it passes through the openings (8a, 8b).

Description: METHOD AND APPARATUS FOR TREATING WASTE MATERIAL The invention relates to a method for treating waste material, in which method waste material is supplied to an apparatus where a conical rotor is placed between stators, and whereby at least the stators have recesses by means of which the material can be transferred through the apparatus when the rotor is rotated, and which rotor has several openings in the axial direction, in which case at least some of the material is conducted through the openings. The invention further relates to an apparatus for treating waste material, which apparatus comprises a conical rotatable rotor placed between stators, whereby at least the stators have recesses by means of which waste material moves through the apparatus when the rotor is rotated, and which rotor has several openings in the axial direction through which openings at least some of the material is arranged to pass. WO 97/21532 discloses an apparatus where a conical rotor is placed between two stators. Helical grooves are arranged in the rotor and/or the stator for extruding the material to be extruded from the extruder when the rotor rotates. Furthermore, an opening or openings are arranged in the travel of the rotor, through which openings at least some of the material to be extruded is arranged to flow. The material to be extruded is made homogenous by means of the apparatus, but the treatment of waste material is inefficient with this apparatus. By arranging a sharp pitch angle for the grooves of the rotor, the material will be ground to some extent at the nozzle of the supply conduit, but this kind of a solution cannot be applied efficiently to the treatment of waste material. Finnish Patent Application 960,589 also discloses an apparatus where a conical rotor is arranged between two stators. At the nozzle of the supply conduit, the rotor has openings through which at least some of the material to be supplied can flow. By arranging the opening to be oblique, the cutting of fibres of the material to be extruded can be increased, but the apparatus of the reference cited is inefficient for the treatment of waste material. The object of the present invention is to attain a method and an apparatus with which waste material can be treated efficiently. The method of the invention is characterized in that the edges of the recesses and the openings of the rotor are sharp, in which case the waste material is conducted through the openings in such a manner that the waste material is ground by means of the sharp edges. Further, the apparatus of the invention is characterized in that the edges of the recesses and the openings of the rotor are sharp in such a manner that the material passing through the openings is ground by means of the sharp edges. The essential idea of the invention is that the apparatus has at least one conical rotor placed between two stators and at least the stator has recesses by means of which the material in the apparatus can be discharged when the rotor rotates. A further essential idea is that in the axial direction of the apparatus, the rotor has several openings through which the material to be treated is arranged to pass and that the edges of the openings and of the recesses of the stator are sharp to the effect that the material to be supplied is ground when it passes through the openings of the rotor. The idea of one preferred embodiment is that the recesses of the stator are at least partly discontinuous to the effect that when a recess ends, the material to be treated is forced through the opening of the rotor. The idea of a second preferred embodiment is that the rear end of the apparatus has recesses that transfer material outwards, which recesses lead to the outlet nozzle of the apparatus and which recesses are arranged into a sharp angle and the flights between the recesses are arranged to be so low that some of the material passes over the flights. The idea of a third preferred embodiment is that cooling means are arranged to the apparatus for cooling the material to be treated in the apparatus. An advantage of the invention is that waste material, such as rubber, PEX, leather or textile waste, can be ground and treated efficiently. By arranging some of the material to pass over the flight between the recesses, the waste material at the flight can be grated into a smaller form. It can be ensured by cooling that the waste material will retain its powdery form. The invention will be explained in more detail in the appended drawings wherein Figure 1 is a schematic sectional side view of one apparatus of the invention, and Figure 2 is a side view of the rotor of the apparatus of the invention. Figure 1 is a sectional side view of the apparatus of the invention. The apparatus comprises an inner stator 1 and an outer stator 2 arranged outside it. At least the outer surface of the inner stator 1 and the inner surface of the outer stator 2 are conical. A conical rotor 3 is arranged between the inner stator 1 and the outer stator 2. The rotor 3 is arranged to move rotatably between the inner stator 1 and the outer stator 2. The rotor is rotated with a motor 5. The motor 5 can be a hydraulic motor or an electric motor, for example, or any other motor known per se suitable for the purpose. The motor 5 is arranged to rotate the rotor 3 by a gear system 4. By means of the gear system 4, the speed of rotation of the rotor 3 can be adjusted as required. But the gear system 4 is not, however, necessary when using an electric motor, for example, as the speed of rotation of the rotor 3 can be easily adjusted by regulating the speed of rotation of the motor 5 in a manner known per se. The apparatus is further provided with a supply conduit 6 along which the material to be treated can be fed to the apparatus. The material to be fed to the supply conduit 6 is supplied with a feeding device 7. The feeding device 7 can be a feed screw or a pump, for example, or any other device known per se. The flow rate of the material to be supplied to the supply conduit can be adjusted by means of the feeding device. The material to be treated flows from the supply conduit 6 through a feed opening 8a to the interior of the rotor 3. After this the material passes in a recess 9 in the inner stator 1 when the rotor 3 rotates outwards from the apparatus, that is, upwards in Figure 1. From the recess 9 the material gains access through an opening 8b outside the rotor and there in a recess in the outer stator 2 further outwards from the apparatus. The recesses 9 are arranged to end in such a manner that substantially all the material to be treated can be made to move through the openings 8b while a recess always ends on the other side of the rotor 3. The edges of the openings 8a and 8b of the rotor 3 are arranged to be sharp and similarly, the edges of the recesses 9 are arranged to be sharp in such a manner that when the material to be treated moves through the openings 8a and 8b, the sharp edges of the openings 8a and 8b and the recesses 9 cut and grind the material to be treated at the boundary surface of the rotor 3 and the stators 1 and 2 in such a manner that the material will be ground. At the rear end of the apparatus, that is, at the end where the material to be extruded is discharged from the apparatus, the recesses 9 are arranged to continue as far as the outlet nozzle of the apparatus and the recesses 9 are helical. In this part, flights 10 between the recesses 9 are arranged to be so low that such a large clearance remains between the flights 10 and the rotor 3 that some of the material to be treated can pass over the flight 10 from one recess to another. In that case the material to be treated will be grated into a smaller form at the flight 10. If the material under treatment is rubber, for example, and a small amount of solvent oil is mixed into the material, a rubber particle can be made to grate open at the flight 10. The rear end of the apparatus can also have helical recesses in the rotor 3, which is illustrated in Figure 1 by means of broken lines. In the rotor 3 the recesses are in the opposite direction to those in the corresponding stators 1 and 2, that is, the helical recesses 9 are crossing, in which case the effect of the recesses on the material is considerable. It is also possible to arrange to the apparatus cooling means, such as a cooling channel 11 by means of which the apparatus and the material treated there can be cooled so that it will retain its powdery form and not get stuck onto the inner surfaces of the apparatus. By supplying a cooling medium to the cooling channel 11 through an inlet channel 12 situated close to the rear end of the apparatus and by conducting the cooling medium out along an outlet channel 13 situated at the front end of the apparatus, the rear end of the apparatus can be cooled more efficiently and heat can be transferred from the rear end of the apparatus towards the front end of the apparatus. Figure 1 shows cooling means arranged to the outer stator 2 but when required, cooling means can also be arranged to the inner stator 1. Figure 2 shows the rotor 3 of the apparatus as in Figure 1. The rotor 3 is rotated in the direction of arrow A. For the sake of clarity, Figure 2 shows only some of the openings 8a and 8b of the rotor 3. The openings 8a and 8b are naturally distributed evenly around the whole rotor 3. Figure 2 shows the recesses 9 in the inner stator 1 by a broken line and the recesses 9 in the outermost stator 2 are described by a line of dots and dashes. At the front end of the apparatus, the recesses 9 are discontinuous and oval and placed obliquely. In that case, the recesses 9 move the material to be treated outwards from the apparatus when the rotor 3 rotates, that is, upwards in Figure 2, and force the material through the openings 8b when they end. At the rear end of the apparatus, the recesses 9 continue as far as the outlet point of the apparatus. For the sake of clarity, Figure 2 does not show the recesses in the inner stator 1 at the rear end of the apparatus. At this end, the flights between the recesses 9 are so low that some of the material can pass over the flights 10 from one recess to another, as illustrated by arrows B. At this point, the pitch angle of the recesses 9, that is, the angle with respect to the horizontal level is rather sharp, such as about 45°, in which case the flow over the flights 10 can be made reasonably great. The pitch angle cannot, however, be too sharp in order that the recesses 9 will transport material all the time outwards and too high counterpressure will not be produced. The apparatus can be easily constructed of separable parts placed on top of one another, in which case it is easy to assemble and disassemble and maintain the apparatus. Further, the stators 1 and 2 can be formed as in Figure 1 of separate parts so that the surfaces which are against the rotor 3 and subject to wear can be changed separately. Many different types of waste material, such as rubber, PEX, leather or textile waste, can aiso be treated with the apparatus of the invention. It is also possible to supply some polymer along with waste material into the apparatus. Then the apparatus is not cooled but it is possible to make an extrusion product containing waste material and polymer, such a tube, a film or a cable sheath or other such product. If the waste material is PEX, crosslinked PEX particles can be oriented at the rear end of the apparatus when passing over the flights 10 as in this place the particles are close to their softening point. The openings in the rotor 3 help to equalize the pressures of different heights on different sides of the rotor 3, for which reason no heavy constructions are required for mounting the apparatus in bearings and for power transfer. By moving the rotor 3 in the axial direction, the clearances between the stators 1 and 2 and the rotor 3 can be adjusted easily and simply in the conical solution. It is easy to adjust the amount to be supplied to the apparatus by means of the feeding device 7. The feeding can be made in such a manner that not an equal amount of material to be treated is fed as there is capacity in the apparatus for treatment, but so-called undersupply is used, in which case the rate of feeding can be easily adjusted and an optimum loading situation can be found for the apparatus. Undersupply can be realized also pulse-like to the effect that a full amount of the material to be treated is supplied through certain supply openings and some of the supply openings are left partially or totally empty so that the material to be treated is distributed substantially evenly all over the apparatus. The speed of rotation of the rotor is also easy to adjust, in which case it is very easy to regulate the temperature of the material to be treated by adjusting the speed of rotation of the rotor and flow rate of the material to be supplied. The drawings and the specification relating thereto are only meant to illustrate the idea of the invention. In its details, the invention may vary within the scope of the claims. In that case, at the rear end of the apparatus, the recesses 9 can be arranged either to the stators or the rotor, or to both. Further, there may be more than one rotor and more than two stators in the apparatus.

Claims: CLAIMS 1. A method for treating waste material, in which method waste material is supplied to an apparatus where a conical rotor (3) is placed between stators (1, 2), and whereby at least the stators (1, 2) have recesses (9) by means of which the material can be transferred through the apparatus when the rotor (3) is rotated, and which rotor (3) has several openings (8a, 8b) in the axial direction, in which case at least some of the material is conducted through the openings (8a, 8b), characterized in that the edges of the recesses (9) and the openings (8a, 8b) of the rotor (3) are sharp, in which case the waste material is conducted through the openings (8a, 8b) in such a manner that the waste material is ground by means of the sharp edges. 2. A method according to claim 1, characterized in that at least at the front end of the apparatus, the recesses of the stators (1, 2) are arranged to end so that when the recesses (9) end, they force the waste material through the openings (8a, 8b) of the rotor (3). 3. A method according to claim 1 or 2, characterized in that at the rear end of the apparatus, the recesses (9) are arranged at a sharp angle and flights (10) between the recesses (9) are arranged to be so low that at least some of the material is conducted over the flights (10) from one recess (9) to another. 4. A method according to any one of the preceding claims, characterized in that the apparatus is cooled when the waste material is being treated. 5. A method according to any one of claims 1 to3, character- i z e d in that in addition to waste material, polymer is simultaneously supplied to the apparatus and a product containing waste material and polymer is extruded with the apparatus. 6. An apparatus for treating waste material, which apparatus comprises a conical rotatable rotor (3) placed between stators (1, 2), whereby at least the stators (1 , 2) have recesses (9) by means of which waste material moves through the apparatus when the rotor (3) is rotated, and which rotor (3) has several openings (8a, 8b) in the axial direction through which openings (8a, 8b) at least some of the material is arranged to pass, characterized in that the edges of the recesses (9) and the openings (8a, 8b) of the rotor (3) are sharp in such a manner that the material passing through the openings (8a, 8b) is ground by means of the sharp edges. 7. An apparatus according to claim 6, characterized in that the recesses (9) at least in part of the apparatus are discontinuous so that the discontinuous recesses (9) force the material through the openings (8b). 8. An apparatus according to claim 6 or 7, characterized in that at the rear end of the apparatus, the recesses (9) are arranged at a sharp angle and flights (10) between the recesses (9) are arranged to be so low that at least some of the waste material passes over the flights (10). 9. An apparatus according to any one of claims 6 to 8, characterized in that the apparatus comprises means for cooling it. 10. An apparatus according to any one of claims 6 to 8, character i z e d in that the rear end of the apparatus has both in the rotor (3) and in the stator (1, 2) helical recesses (9) which are arranged so that in the rotor (3) they are in the opposite direction to those in the corresponding stator (1 , 2), that is, crossing.

Inventors: KIRJAVAINEN KARI, KIRJAVAINEN, KARI
Applicants: CONENOR OY, KIRJAVAINEN KARI, KIRJAVAINEN, KARI
Application year: 1998
Main classification: B02C2
IPC codes: B02C2, B02C18, B29C47