MXPA01009539A - Laminar polyolefine plastic material recycling installation - Google Patents

Abstract

The invention relates to a laminar polyolefine plastic material recycling installation comprising:plastic material crushers (6);sorting devices (10) to separate dense material;mills (26);water decanting deposits (62, 68) with a lower outlet and a feeder delivering the material to the bottom (72) of the deposit (62, 68), in addition to a pump (78) communicating with a passage (74) and fitted with an outlet (80);mobile means (82) to generate a water and materials suctioning flow through the inlet (76) and a propelling flow through the outlet (80);a variable speed motor (84) which can drive the mobile means (82) in such a way that a change in speed causes a change in the volume of flow.

Description

INSTALLA TION FOR R EC I C TI D MATERIAL PLASTI CO LAM I NAR POL I OLEF I N The present invention relates to an installation for recycling polyolefin plastic sheet material, the installation being of the type comprising: [i] at least one breaker mechanism of the plastic material to be recycled; [ii] at least one first separating device, for flotation separation of materials of greater density than said plastic material, [iii] at least one grinding mill, for reducing said plastic material to particles of small dimensions; [iv] at least one settling tank in water which, on the one hand, is provided with blades for surface displacement of said particles of small dimensions and, on the other hand, is provided with a bottom in which there is a step of exit; each settling tank being provided with a feeder able to receive the crushed plastic material and, at least partially, separated from higher density materials, delivering said material in the vicinity of said bottom, there being a first speed motor capable of suitable variation to regulate said delivery; [v] means for separating said plastic material from said water; and [vi] means for agglomeration of plastic material. In particular, said installation refers to poiolefin plastic sheet material, without load, coming from selective collection and separation, that is to say after being used (Post-consumption) in polyethylenes (PE), polypropylenes (PP), ethylene-acetate vinoílo (EVA) and polybutylenes (PB); hereafter, the present description and claims relate exclusively to these plastic materials, whose density (if they are not loaded) is less than 1 g / cm3. As is known, the consumption of laminar plastic material is becoming more frequent, preferably for wrapping and also for forming container bags. This laminar plastic material is usually discarded after its use and this fact poses important ecological problems, particularly taking into account that most of these plastic materials are not biodegradable. Therefore, the current regulations and the global trend is to promote recycling, creating infrastructures for the collection, selection and recycling of plastics, such as packaging. With the recycling of these laminar plastics, on the one hand the regulations are met, the pollution is reduced and an economy is obtained, as a consequence of a lower oil import, from which these plastics derive. However, usually known facilities have drawbacks and among them it is worth noting what is the subject of the following comments. One of the important elements for an installation to recycle polyolefin plastic sheet material, is that it is constituted by one or more tanks of decantation in water; these are of inverted trunk-conical background and when they are more than one, they are communicated superiorly to each other, with which a leveling between the deposits is established; they also have two vertical descending feeders, which are submerged in the aforementioned tanks and which, by means of augers, drive the chopped plastic material to the vicinity of the bottom of the decanting tank: Once there, the plastic material having a density Less than water, it tends to rise to the surface of the water contained in the tank. Conversely, higher density materials, plastics, etc. (and that are not usable) tend to be at the bottom of the tank and for disposal, there is a controllable outlet for each vertical deposit. In each of the vertical tanks, it is necessary that the water and liquids in general that they contain, have a high degree of cleanliness; this need implies a renovation of said waters and therefore a water outlet, which is compensated with a clean water inlet. In addition, this water outlet evidently involves the exit of sludge, impurities and plastic particles of density greater than that of water and that are therefore in the vicinity of the bottom of the tanks, frequently associated with other particles of lower density.

Consequently, the function of the aforesaid controllable outlet is to regulate the amount of water (together with sludge, impurities, plastic particles discarded and others) that must leave the vertical tank to be led to the drainer. the structure of each controllable outlet is as follows: an elbow pipe communicates the lower vertex of the liquid tank with the upper zone of a drainer located at a lower level of the maximum water level of the tank, the lower area of this drainer (which is where the evacuation mouth of the same is located) is at a level lower than the liquid entry and between both areas is interposed a wire mesh, perforated plate, grid or similar, arranged in inclination and that separates the water from the cited muds, impurities, plastic particles, etc., disposable The amount of water that comes out of the tank is proportional to the smaller cross section of the tube The angle between the water level in the tank and the height of the aforementioned inlet of the squeegee, therefore, for the regulation of the aforementioned amount of water, one of the factors indicated in the previous paragraph; since it is not easy to change the aforementioned height difference (which would imply the vertical displacement of heavy bodies), the regulation must be obtained by varying the aforementioned section and this variation is not feasible by means of for example a butterfly valve or other type of known valves, since with them a jam will easily be produced by the inevitable retention of sludge, impurities and plastic particles present in the water. Consequently, in the usual known installations, this necessary regulation is carried out using a plurality of calibers and making the pertinent substitutions in each case. Obviously, this regulation involves disadvantages of some importance, since it is necessary to have a first valve located upstream of the place of placement of these calibres and of a second valve located downstream of the place of placement of these sizes; close these valves with the consequent stoppage of the process; replace the gauge and reopen the aforementioned valves in order to continue with the process. The invention aims to overcome these drawbacks, this purpose is achieved with an installation of the type indicated at the beginning, which is characterized in that it comprises a pump equipped: an input mouth communicated with said outlet step; an exit mouth; movable means apt to promote a suction flow of said water and said materials through said inlet mouth and a flow of said water and said materials through said outlet; and a second motor suitable for driving said mobile means, said second motor being of speed capable of being subject to variation, so that said variation of speed of said second motor causes a variation of the flow rate of said flows. Other advantages and features of the invention can be seen from the following description, in which, without any limiting character, a preferred embodiment of the invention is described, with reference to the accompanying drawings. The figures show: Fig. 1, a schematic view in elevation, partially sectioned, of part of the installation object of the present invention, the view being interrupted by the right. Fig. 2, a schematic elevation view of the other part of the installation, from the indicated interruption and as a continuation of the previous Fig. 1; this view is also interrupted by the right. Fig. 3, a schematic elevation view of the rest of the installation, from the last mentioned interruption and as a continuation of the previous Fig. 2. Fig. 4, a schematic section of an embodiment of the pump. Fig. 5, a schematic perspective view of the deposit that receives the water from the decanting tanks. Fig. 6, a view in axial direction of the assembly formed by the shaft and the blades attached to this axis and moving the particles of plastic material from the surface of the water contained in the decanting tanks.

Fig. 7, a perspective view of an assembly analogous to that shown in Fig. 6. The installation object of the present invention comprises a conveyor belt 2 that preferably starts in the vicinity of a cavity 4, in order to avoid excessive dispersion of the plastic material to be recycled; the belt 2 lifts this material until it is poured into the breaker 6; it comprises a drum and teeth and preferably rotating in alternate directions, destroys the sheets of plastic material until they are left in pieces whose dimensions are substantially reduced with respect to the initial dimensions of the plastic. Said plastic pieces leave the breaker 6 at the bottom thereof and fall on a second conveyor belt 8, which elevates them to a container 10 that acts as a separating device; the container 10 contains water and impurities of higher density than the plastic, such as earth, metals and others, are collected therein. In the container 10, the plastic material to be recycled floats and the impurities and also some of the plastic pieces of greater density than that of the water, fall by gravity to the bottom of the container 10. It is preferable that this bottom is formed by two conical cavities or inverted pyramids 12 that are provided with extreme outlet mouths 14 that allow the expulsion of unusable materials; each of these extreme mouths 14 allows access to an auger 16 moved by respective gearmotors 18; the two augers 16 are connected to a central valve 19 communicating with another auger 20 which is preferably connected to a general refuse collection manifold 21 which is schematically represented. It is noted that when the end ports 14 are open, the central valve 19 is closed and vice versa. The water contained in the container 10 defines an upper surface in the vicinity of which float the plastic pieces that are to be recycled; the installation foresees the existence of shovels 22 that lead these pieces of plastic to an edge of the container that is opposite to that through which they have entered; this surface of the container is of a certain extension and the movement induced by the blades 22 is slow, all with the purpose of favoring the precipitation of the materials of greater density. In the vicinity of said opposite edge is another conveyor belt 24, which collects the pieces of floating material (plastics and non-plastics) and leads them towards a grinding mill 26. This mill 26 has a structure 28 that provides an upper access 30. which preferably allows the entry of plastic material and also allows the entry of water. The mill is not represented in detail; It consists of a bottom in which the plastic material enters and this bottom is constituted by a plate with a concavity directed downwards and provided with holes, which obviously only tend to allow the passage of plastic pieces of conditional dimensions to the diameter of the holes themselves. Faced with the aforementioned concavity of the perforated plate, there is a rotating lathe equipped with radial blades; on the other hand, the mill 26 has fixed blades, logically located in the vicinity of the winch. During the rotation of the radial blades, they pass in the vicinity of the fixed blades, so that a break of the pieces of plastic material occurs, until the desired dimensions are reached, which are of the order of a few thousand meters. These pieces or particles of plastic material are wet, since as indicated, water (adjustable according to need) enters the interior of the structure 28 in which the mill is located 26. To collect the pieces of plastic material from small dimensions and that have passed through the holes of the sheet referred to in the previous paragraph, there is a new auger 31 that allows the transfer of these pieces to a centrifuge 32 (Fig. 2). This centrifuge 32 is for treating and washing the wet pieces or particles of plastic material; It is formed by a prismatic plate equipped with small holes of small dimensions, which allow the passage through it of the water found in the pieces of plastic material but which prevent the passage of the pieces themselves. Inside the prism formed by the plate is a tree equipped with blades, which is rotatable, so that during its rotation it drives the particles of materials against the enveloping plate. Through an extreme mouth of this plate the moist plastic laminate material can enter the interior of the prism formed by the plates; by said space, during its displacement along the prism, the friction to which the pieces or particles of material are subjected by the action of the centrifuge 32, produces its cleaning, until the exit of the pieces takes place by a second mouth opposite the entrance. Immediate to said outlet is a fan 34, for extracting these pieces of material and their conduction to a cyclone 36, after which there are two settling ponds 38, located in parallel; in the figures, only the previous raft can be seen. For reasons of space and transport, it is preferable that this cyclone 36 pour into the edge of the rafts 38 which is located to the right in Fig. 2. These rafts 38 present a great analogy with the container , since they contain water, on whose upper surface the plastic pieces float; shovels 40 (referenced again below) advance these plastic pieces from the aforementioned entrance edge to the opposite edge. It is preferable that the bottom of the rafts also be formed by two inverted pyramidal cavities 42, provided with respective lower deposits 44 that collect the waste elements, of greater weight than the usable plastic pieces; the communication between the cavities 42 and the lower tanks 44 is regulated by means of first regulating devices (or valves) 46; on the other hand a few second regulating devices (or valves) 47 allow the communication of the lower tanks 44 with another lower evacuation conduit 48 (endowed with a worm) which is usually indirectly connected to the general waste collection manifold 21 to which it has already been referred to above. Actuation of the regulating devices 46, 47 frequently causes difficulties and to avoid them, it is preferable to have an arm 50 communicated (directly or indirectly) with the lower evacuation duct 48, this arm 50 is arranged in elevation and presents a ejection mouth 52 which reaches a height above the level of water contained in rafts 38 (first level); an auger 54 causes the rise of the waste products along the arm 50. With the arrangement described above, decompression problems are avoided in particular. On the other hand, during operation of the installation, valve 46 and valve 47 are open simultaneously; it is also foreseen that the duct 48 forms part, directly or indirectly, of the general manifold 21. There is a noria 56 that allows to collect the pieces of plastic material that have advanced by the action of the blades 40 and this ferris wheel 56 serves to deliver these pieces to an auger 58, which is variable speed. This auger 58 is connected to a feeder 60 which is preferably descending vertically and is moved by a first motor 61 whose speed can be varied; the feeder 60 is formed by another auger contained in a tubular device which, in turn, enters a tank 62 in which a new separation operation of unusable materials must take place. The reservoir 62 contains water and also in this case, it is provided that on its surface the pieces or particles of plastics material are partly purified and there are other paddles 64 (also referred to again below) that advance these pieces, up to a ferris wheel 66 for, where appropriate, delivering these pieces to at least another deposit 68, substantially twin of the deposit 62; then both are described at the same time. In both tanks 62, 68 the outlet mouth 70 of the corresponding feeder 60 is close to the respective bottom 72 of the tank 62, 68. In this way it is forced that, on the one hand, the pieces of plastic and materials received from the auger 58 enter the tanks 62, 68 at a certain distance from the water surface of the tank; on the other hand, at a certain distance from the tubular part of the tanks 62, 68 and also at a certain distance from the outlet passage 74 of the bottom 72 of the tanks 62, 68. These bottoms 72 are conical in shape and their completion The lower part is constituted by the exit passages 74. It can be seen that in the example shown, the two tanks work in series, that is, the material to be recycled runs first through one of the tanks and is then conducted to the remaining tank. The pieces of plastic material access the interior of the tanks 62, 68 through the corresponding feeder 60; those that are of lower density than water (pieces of light material) tend to ascend through the interior of the deposit and, conversely, those that are denser than water, tend to descend. However, it is the case that some of the latter are either of density only slightly greater than that of water or they are adhered to other pieces of plastic of light material; consequently, these pieces have a very reduced mobility, which makes it difficult to conveniently separate the pieces of light material (ie, those that are recyclable) and the heavier pieces, which must be discarded. To cope with this situation, each of the outlet passages 74 is connected to the inlet 76 of a pump 78 (Fig. 4). This pump 78 also has an outlet 80 and mobile means 82, whose movement is produced by a second motor 84 whose speed can be varied; all this in such a way that the said movement causes a suction flow of the water and of the materials located in the tank 62, 68 and this suction flow enters the pump 78 through the inlet mouth 76; This flow is controllable at will and continuously, so that a variation in its speed does not require the stoppage of the installation. At the same time that the suction flow is produced, the pump 78 promotes a flow of impulsion of its own water and of the materials it contains, so that this flow of impulsion passes through the outlet mouth 80; later on, the subsequent course of this impulse flow is indicated. Obviously, the fact that the motor 84 is of variable speed, causes a variation of this speed to induce a variation of the intensity of said suction and discharge flows. With this, a downward stream of water (together with the materials contained therein) is generated inside each reservoir 62, 68; this current motivates an important activation of the movement of the plastic pieces of reduced mobility, to which reference has been made above; It is also common to promote the separation of pieces of light material adhered to other pieces of material of greater density than water. The result is a significant improvement in the process of separation of both types of materials, along with a shortening of the time used in the process. However, if the suction flow is too intense, it also aspirates pieces of light material, overcoming the tendency of these to ascend through the interior of the deposit, which is not desirable.

It is also not convenient for the speed of the first motor 61 of the feeder 60 to be high, since in this case an excessive amount of plastic material is supplied, which results in an excessive concentration of such plastic material in the vicinity of the bottom 72 of the tank Decanting 62, 68; This can also cause pieces of light material to receive the effect of the suction flow. To avoid this possible drawback, the invention also provides for manual variations of the speeds of the first motor 61 and / or of the second motor 84 (especially of the latter), depending on the plastic materials aspirated and which logically are also found in the mentioned flow of impulsion. To facilitate the observation of these plastic materials, there is a point of easy observation of them and from which the necessary variations can be ordered and synchronized in the mentioned speeds of the motor 61 and / or the motor 84, until it is adequate the content of plastic material that is extracted together with the water. The materials that are rejected are those that impede a good final quality once the plastic is recycled and converted into pellets. This is precisely the object of this synchronized purification performed by the vertical auger driven by the motor 61 and the mobile means driven by the motor 84. Logically, the water outlet that takes place through the outlet passage 72, is compensated with a water entrance; later on, reference is also made to this point, pointing out that this water renewal improves and benefits the separation process. It is emphasized that the synchronization referred to causes an adequate suction flow and therefore a correct separation of the materials that could damage the quality of the recycling that is the purpose of the installation described. In the non-limiting example shown in FIG. 4, the pump 78 is a helical pump equipped with a rotor 82 (acting as a moving medium) with a straight cross section of a circular and constant shape and helical conformation; this rotor rotates inside a stator 86, which is internally covered by means of an elastic or flexible material 88 which gives it a helical configuration, with an elongated section and with a thread pitch equal to that of the rotor 82. In all there is a continuous line of alternative contact between the rotor 82 and the stator 86, so that, when the pump 78 is in operation by the action of the motor 84, the rotating movement of the rotor promotes that the spaces delimited between the The rotor and the inner surface of the stator move in the axial direction, resulting in suction and impulsion effects. Logically, the same results can be achieved with many other types of pumps, among which, by way of non-limiting example, other types of pumps can be mentioned, such as peristaltic, pneumatic double diaphragm, flexible sleeve, flexible impeller pumps , lobular rotaries and others. Between the two tanks 62, 68 there is a communication in the form of communicating vessels (not shown) and in it there is an exit line that acts when a certain level is exceeded, which on the one hand equalizes the levels of the two deposits and on the other hand there is a maximum level regulation also for the two deposits. The existence of a reservoir 90 is preferred, which is shown in FIG. 2 and in more detail in FIG. 5. The outlet mouth 80 of each of the pumps 78 is connected to a conduit 92 receiving said flow. of drive and each conduit 92 has a drain 94 that pours on trays 96 so that the water supplied overflows by an edge 98 of these trays which is lower than the other edges. The overflow along the entire length of the edge 98 causes water and plastic materials to fall over the full width of a cover 100 that is sloping downward and that is provided with a plurality of openings; the cover 100 may be of perforated plate or of mesh and in any case, the openings are of sufficiently small dimensions to prevent the pieces of material to be discarded from passing through them. With this, the water passes through the cover 100 while the pieces of material to be discharged slide along the cover 100, until they are received by a new auger 102, which, if necessary, leads them to the general collector 21. By means of a conduit 103 and suitable pumps, it is possible that the water recovered in the tank 90 is led to the top of the settling tanks 62, 68 whereby a practically closed circuit is formed. It is also preferred that at the outlet of the tank 68 there is a press 104 for draining the product that accesses it, causing a significant separation of the water with respect to the plastic material to be recycled. The installation also comprises at least centrifuges 106 for receiving the usable plastic material coming from the press 104; these centrifuges 106 can be of the same type as the centrifuge 32 described above, although they operate at different speeds. After the first centrifuge 106 there is a fan 108 which sends the plastic material to the lung 1 10 to subsequently access the second centrifuge where it is subjected to a new drying process. Again a fan 12 and a lung 1 14 intervenes, to direct the plastic material to a reservoir 1 16, from where it is sucked by a new ventilator 1 18, to access the lung 120, after reception of hot air by means of the heater 122. From the lung 120, the plastic material passes to another reservoir 124 and there is a conveyor 126 for dosing and transporting the material to an agglomerator 128, where the drying and final agglomeration of the recycled plastic material is achieved. The blades 64 (Figs 6 and 7) are fixed to a rotating shaft 130 and it is preferable that they present a section 132 immediately to the axis from which it projects radially, followed by an end portion 134, curved, which determines a convexity, which is located previously in the direction of rotation of the axis 130; the blades that are in the same stretch of the shaft 130 are distributed regularly and are offset in width with respect to fasfas fixed in the contiguous axes. With all this a smooth movement of advancement of the plastic pieces that are in the vicinity of the surface of the water contained in the decantation tanks and avoid undesirable turbulence is achieved.

Claims (5)

RECIPE ND ICAC IONS

1 . Installation for the recycling of polyolefin plastic sheet material, in which the installation is of the type comprising the following: [i] at least one breaker mechanism (6) for the plastic material to be recycled; [ii] at least one initial separation device (10) for separating, by means of flotation, material of greater density than that of the above plastic material; [iii] at least one grinding mill (26) to reduce this plastic material to small particles; [iv] at least one water separation tank (62, 68) which, on the one hand, is equipped with several blades (64) for surface displacement of these small particles and, on the other hand, is equipped with a bottom ( 72) having an outlet (74); each separation tank (62, 68) is equipped with a feeder (60) suitable for receiving the plastic material that has been crushed and, at least partially, separated from higher density materials, delivering such material close to that bottom (72). ), with an initial motor (61) of variable speed, this motor being suitable to regulate this delivery; [v] means to separate this plastic material from that water; and [vi] means for gluing the plastic material, and comprising a pump (78) equipped with: an inlet (76) connected to that outlet (74); an exit (80); various mobile devices (82) suitable for promoting the suction flow of this water and these materials through that inlet (76) and a propulsion flow of this water and these materials through that outlet (80); and a second motor (84) suitable to drive these mobile devices (82), this second motor (84) being of a suitable variable speed so that this variation of speed of this second motor (84) causes a variation in the rate of flow of these flows, characterized in that said water sucked through said inlet (76) is recirculated through a duct (103) to the upper part of said water separation tank (62, 68). The installation according to claim 1, characterized in that such speed variations and synchronizations of that first motor (61) and / or that second motor (84) are manually made, depending on the content of plastic materials in such a propulsion flow. . 3. The installation according to claim 2, characterized in that it has suitable means to facilitate the observation of such content of materials in such propulsion flow. The installation according to at least one of claims 1 to 3, characterized in that said outlet (80) of said pump (78) is connected by means of a duct (92) suitable for receiving said propulsion flow and emptying it. through a drain outlet (94); there being [a] a tray (96) located under said drain (94) and provided with an overflow edge (98) defining a length and [b] a cover (100) of a width of the order of said length, located below said edge (98), which is in descending inclination and which is provided with a plurality of openings suitable to prevent the passage through said materials. 5. - Installation according to at least one of the claims 1 to 4, characterized in that said pump is a helical pump (78) comprising an eccentric rotor (82) of constant circular cross section, said rotor (82) being able to rotate inside a stator (86) of helical shape , internally covered with an elastic or flexible material (88), there being at all times an alternative line of contact between said rotor (82) and stator (86), so that the rotation of the rotor (82) inside the stator (86) promotes delimited spaces between the rotor (82) and the inner surface of the stator (86) that move axially; there being a motor element (84) capable of promoting the rotation of said rotor (82) at a plurality of speeds. 6. Installation according to at least one of claims 1 to 5, comprising at least one settling basin (38) capable of holding water up to a first level and particles of small dimensions of material, said raft (38) being provided with a bottom (42) constituted by at least one cavity of inverted pyramidal configuration that is in lower communication with a reservoir (44), there being a first regulating device (46) to regulate the communication between said reservoir (38) and said reservoir (44) and a second regulating device (47) to regulate the communication between said reservoir (44) and a lower evacuation conduit (48), characterized in that said lower evacuation conduit (48) is in turn connected to an arm (50) arranged in elevation that has a vent mouth. ejection (52) that reaches a height above said first level of said water, there being an endless (54) able to promote the rise of said particles of material to be rejected by the interior of said arm or (50). 7. Installation according to at least one of claims 1 to 6, characterized in that it is provided with at least one centrifuge (32, 1 06) for treatment of wet particles of plastic material, said centrifuge (32, 106) comprising : an encircling plate of prismatic shape, defining a space and equipped with holes whose small dimensions prevent the passage of said particles; a first mouth apt to allow the passage of wet laminar plastic material into said space, a tree provided with blades, rotating inside said envelope sheet and apt to drive said particles against said covering sheet; and a second mouth suitable for allowing the exit of plastic material from the interior of said space. 8. Installation according to at least one of claims 1 to 7, characterized in that said blades (40, 64) are fixed in successive sections of a rotating shaft in a first direction of rotation, so that: [a] each blade (40, 64) presents a section immediately to the axis disposed radially with respect thereto and a curved end section, which determines a convexity, (to which it is disposed previously in said first direction of rotation; [b] each of the blades (40.64) that is fixed in a same stretch of said axis, forms equal angles with the adjacent blades fixed in the same stretch, and [c] the blades (40, 64) that are fixed in the same stretch are de-phased angularly with respect to the blades (40, 64) fixed in an immediate stretch.