GB2162117A - Recycling thermoplastics sheet waste into an extruder - Google Patents

Abstract

Sheet waste of relatively low bulk density is disintegrated into particles or flakes, and mixed with thermoplastics granulate of relatively high bulk density, in a uniform feed stream, and introduced into an extruder (109). Separate thermal regeneration of the waste is rendered unnecessary and ensuring thermal decomposition of the waste does not take place. The process can be carried out by a simple and operationally reliable apparatus (10), which possesses a fall shaft (11) having two mixing zones (M<1>, M<2>) one above another; in these zones, waste particles (129) conveyed in an air stream are mixed with a portion of the granulate (151) suppled from a passage (161) and the mixture is then combined with the remaining portion (152) of the granulate, supplied into the base of the fall shaft (11) through apertures (221), the air from the waste particle stream being vented from shaft (11), by vents (114), above the apertures (221). <IMAGE>

Description

SPECIFICATION Recycling thermoplastics waste This invention relates to a process for the recycling and recovery of thermoplastics waste for example waste from thermoplastics sheets, such as is continuously produced in the form of edge strips in the manufacture of polyolefin foils or sheets with edge trimming. The invention also relates to an apparatus for producing a stream of thermoplastics granulate and flakes suitable for direct feeding into an extruder and to a thermoplastics processing plant for carrying out the recycling process.

The term "Restoration" (German word "Ruckfuhrung" in the original text from which this specification was prepared) of thermoplastics sheet waste is to be understood here as the use of material known as "Recycling"; the term "Recovery" (German "Ruckgewinnung") of thermoplastics sheet waste is to be understood here as the reclamation of the thermoplastics materials contained in the waste in the form of finished products or semifinished products, e.g. foils and sheets or other thermoplastics extruded materials, and generally with the addition of fresh and/or regenerated thermoplastics granulate. possibly with the usual additives, pigments and the like.

Sheet waste presents particular problems in the recovery of thermoplastics materials because, amongst other reasons, the heating of sheet wastes for producing granular regenerate leads, on account of the relatively large specific surfaces, to an increased oxidative breakdown and to considerable reduction in quality of the thermoplastics material.

The usual recovery of thermoplastics from foil waste is based upon the concept that the foil waste, optionally after disintegration, is heated for the purpose of forming granulate or granular extrudate to a sufficiently high temperature to bring it into an at least plastic state; the thermally granulated regenerate obtainable from sheet waste therefore not only has a cost disadvantage due to heating costs, but also an increased loss of quality, which can be determined only with difficulty or uncertainty, for example by continually measuring the melt index, which loss increases the risk of irregularities in the viscosity and melt flow during extrusion of thermoplastics materials containing such regenerate.

It would appear desirable to avoid the separate thermal granulation of the thermoplastics sheet waste by using sufficiently disintegrated waste ("foil chips") of thermoplastics foil or sheet material directly as feed for a production extruder; for production operation, however, more thermoplastics material is normally required than is available in the form of sufficiently homogeneous sheet waste material. Therefore the sheet waste is mixed with usual feed material, which has the usual bulk densities typically of 0.4 to 0.6 kg/dm3 or more for granulate or regenerate; sheet or foil chips which have a bulk density approximately 3 to 10 times lower and typically less than 0.1 kg/dm3, correspondingly have a tendency when mixed with granulate to "float", which means that the feed mixture for the extruder is not uniform.

In thermoplastics sheet production factories, where by. cutting and trimming extruded foil sheet material, a continuous stream of waste of edge strips is produced, the processing of the foil waste is a problem which has not been solved satisfactorily. Attempts have been made to solve the problem either by centralizing the recovery (i.e.

regeneration outside the firm) or by the installation of special equipment (i.e. "in-house" regeneration).

In the former case, on account of the necessity for baling presses and storage rooms, additional investment including operational and personnel expenses cannot be completely eliminated, and there is the usual loss of value of approximately 50%.

In the second case, i.e. in sheet waste regeneration by in-house processing, either the problem of material uniformity must be solved, for example by sorting according to colour and/or material differences, or homogeneity must be dispensed with and a mixed regenerate must be accepted which is suitable only for low cost products, such as garbage bags or construction sheets. Added to this is the problem of the build-up of electrostatic charges on the sheet waste material and the resultant accumulation of dust in the waste.

In the search for an effective and economical solution to the in-house regeneration of sheet waste, which enables the above problems to be solved with acceptable expenditure on apparatus and running costs, various systems were investigated in the course of the research of the applicant leading to the present invention. It was first established that the problems of sorting and dust accumulation can be solved virtually only with "in-line" plants (in the production stream), i.e. by recycling the foil waste stream generated on a given production line continually and preferably without intermediate storage into the material feed for this line or a parallel production line operating with the same or compatible material.

Both compresgion/cutting methods, which supply a pellet-like material or operate with forced feed, and also secondary extrusion methods, in which the waste is plasticized in a smaller auxiliary extruder and introduced from this into the main extruder, were investigated.

The results were not satisfactory, in the first case mainly due to lack of reliability of a uniform material feed, and in the second case because the plant costs were too high.

An object of the present invention is to provide a process suitable for the recycling of thermoplastics sheet or foil waste for thermoplastics processing, which can be carried out "in-house" and "in-line" and which make possible, at comparatively low installation and operational cost, a relatively troublefree and value-preserving reprocessing of thermoplastics sheet waste.

Another object of the invention is to provide an apparatus or thermoplastics processing plant suitable for carrying out such a process.

Surprisingly, it has been found that these ob jects, contrary to expectation, can be achieved without a special thermal or compressive regeneration step by a simple mixing method, in which one does not attempt to reduce the differences in the bulk densities of granulate and foil waste for example by compression of fusion, but on the contrary retains or even increases these differences.

The process according to this invention for recycling thermoplastics sheet waste into a thermoplastics process is characterized in that the thermally non-regenerated sheet waste is introduced into an extruder continuously supplied with thermoplastics granulate by forming from particulate, and preferably flakey, disintegrated sheet waste of relatively low bulk density and thermoplastics granulate of relatively higher bulk density, a mechanically stabilized, virtually uniform feed stream from the disintegrated sheet waste and the thermoplastics granulate and introducing this feed stream into the extruder.

The term "particulate, disintegrated sheet waste of relatively lower bulk density" is understood to mean a waste the bulk density of which, expressed for example in units of kg/dm3, is at most one-third (33%), preferably less than onefourth (25%) and typically approximately one-fifth (20%) or less the bulk density of the thermoplastics granulate expressed in the same units, which latter accordingly has a "relatively higher" bulk density and may consist of usual fresh and/or regeneratively obtained, granulated material.

Typically, the bulk density of the particulate, disintegrated sheet waste is about 0.1 kg/dm3 or less, whereas the bulk density of the granulate in the same units is about 0.5 or more.

Preferably, the largest particle dimensions of the sheet waste particles on average (e.g. determined by sieving) are not more than three times as large and preferably not more than twice as large as the largest average particle dimensions of the granulate (e.g. also determined by sieving).

According to the invention, the feed stream is mechanically stablized; this means in connection with the invention a state of distribution which exhibits, during continual feeding into the extruder, little or virtually no segregation effects. in general this state of distribution is achieved according to this invention in that the waste material, e.g. edge strips, mechanically processed for example in a mill for forming sheet flakes, is united in a falling stream, for example in a drop shaft, with a first granulate partial stream to give a premixture, which is then united, usually in the form of a bedding, with a second granulate partial stream to give the stabilized feed stream.The granulate particles produce, in the falling stream, a "hail-like" precipitation effect on the flakes and fix them in the premixture bedding being produced, which collects near the lower end of the fall shaft and is continually drawn with the granulate of the second partial stream into the extruder.

The sheet flakes, formed for example in a knife mill and conveyed by a conveying blower through a sieve into a cyclone separator, can be combined in a falling air stream with a first granulate partial stream to give a premixture; the air stream can then be conducted, through appropriate slits in the lower end of the fall shaft and through a bed of thermoplastics granulate which surrounds the lower end of the fall shaft, in order to retain any residues of foil flakes in the granulate bed acting in the manner of a filter.

Since the process of this invention and the apparatus therefor, is relatively simple, it may be carried out even with relatively low rates of foil waste production in in-line operation, for example by the feed stream formed according to this invention being fed back again to the extruder which produces the foil from which the waste is obtained.

The apparatus according to this invention can accordingly be constructed as an auxiliary device to a conventional extruder and is characterized by a fall shaft, for example an approximately vertical fall pipe with rectangular, circular or polygonal cross-section; the upper end of the shaft is connected with a source of foil flakes, e.g. a mill; the lower end of the fall shaft leads to the feed opening of the extruder and through the machine hopper which surrounds the lower end of the fall shaft; into the fall shaft there opens a first, upper granulate feed and a second, lower granulate feed; the fall shaft constitutes, between the two granulate feeds, an upper mixing zone for producing a falling stream consisting of a premixture of granulate and flakes; at the second granulate feed there occurs a lower mixing zones for producing a particle bedding, in which the premixture is continually combined with granulate from the lower granulate feed and then introduced as feed stream into the extruder.

If the apparatus according to a preferred embodiment of the invention, is used as a part of a thermoplastics processing plant for carrying out the process according to the invention and is connected, as feed plant, directly with an extruder, the feed stream can form a material cover lying on the screw of the extruder, which cover, before being drawn into the extrusion cylinder and possibly also while being drawn in, is thoroughly mixed by the screw and screw thread before the material drawnin is compressed and plasticized in the extruder.

Preferably, the apparatus according to this invention comprises an upper granulate storage vessel formed generally as a funnel, from which a first granulate line leads to the fall shaft and there defines the start of the first mixing zone; this first granulate line may have, in general, a slide valve or similar device, by which the quantity of granulate arriving in the first mixing zone per unit time can be controlled or regulated. A second granulate line leads from the upper granulate storage vessel to the machine hopper in such a manner that its outlet determines the level of the granulate bedding in the machine hopper, which surrounds the fall shaft. Consequently, topping-up with granulate can be limited to the upper granulate vessel and can be monitored there automatically, if desired, since the granulate bedding in the machine hopper is automatically maintained by the second granulate line at the level defined by the position of its outlet.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic partial view of a thermoplastics processing plant suitable for carrying out a process according to the invention and comprising one embodiment of apparatus according to the invention, Figure 2a is a half-schematic, cut-away sectional elevation of an apparatus according to the invention, and Figure 2b shows the apparatus of Fig. 2a in section taken on line A-A of Fig. 2a.

The schematic view of Fig. 1 shows a partly cutaway, highly simplified section through a thermoplastics processing plant 1 for carrying out a process according to the invention. The plant 1 includes apparatus 10 according to this invention, which comprises of a generally hollow fall shaft 11, for example of rectangular cross-section or of cylindrical form, and a machine hopper 14.

The upper end 110 of the fall shaft 11 is connected with the outlet end of a source 12 of thermoplastics sheet flakes 129, which source includes an apparatus 120, e.g. a knife mill, for forming the flakes 129 from sheet strips 131, of a conveying blower 121 and a cyclone 122, which supplies the upper end 110 of the fall shaft 11 with a falling stream of sheet flakes 129. While the main portion of the air stream generated by the conveying blower 121 flows away upwards in the cyclone through the line 123, a portion of the air stream comprising the flakes 129 can enter the fall shaft 11 downwards and influence its fall speed.

Into the fall shaft 11 there opens an upper or first granulate feed 151 as the outlet of a first granulate line 161 from the upper granulate partial stream into the funnel 16, to feed a granulate partial stream into the fall shaft 11, for example under the influence of gravity. The quantity of granulate fed by this granulate partial stream per unit time into the fall shaft 11 can be controlled or regulated, manually or preferably automatically, for example by a valve 163 or the like.

The upper granulate feed 151 defines the upper end of a first mixing zone M', in which the granulate particles 169 form a premixture with the flakes 129 in the fall shaft 11; the mixing zone Mis a comparatively dynamic mixing zone, in which the components to be mixed together move relatively rapidly (of the order 10-to 102 m/sec).

As a result of the relatively high bulk density of the granulate particles 169 (which is a consequence of the form of the particles, as in the case of the sheet flakes 129), the granulate particles 169 exert upon the foil flakes a kind of "hail effect" in the sense that the granulate particles 169, when falling through the mixing zone Mr, entrain the sheet flakes with them and form with the latter, at the lower end of the mixing zone M', a bed of the resultant premixture; in this premixture bed, the flakes are fixed between the granulate particles in the sense that the granulate particles 169 with their larger mass per particle compared with the flakes 129, form a movable granulate matrix, in the interstices of which the flakes or flake groups are caught and move with the matrix, but are not precipitated from the matrix.The premixture then passes into the second mixing zone M2, which is relatively static and has a typical movement speed of the order of 10-Z to 104 misec.

In the mixing zone M2, the premixture bed of flakes 129 and the first partial stream of granulate particles 169, formed at the lower end of the mixing zone Mr, is united with the second partial stream of granulate particles 169; this second partial stream is supplied from the granulate bed 149, which lies in the machine funnel 14 and in the lower part surrounds the fall shaft 11 at least up to the height at which the lower granulate feed 152 is disposed.

In general, the fall shaft 11 has a plurality of air outlet openings 114, which are so constructed by appropriate covers, louvres, slit widths, gratings or the like that air from the mixing zone M' can pass outwards through the granulate bed 149 but virtually no granulate particles 169 can escape from the bed 149 into the mixing zone M. It will readily be seen that the bed 149 thereby acts as a filter for the air flowing downwards through the fall shaft 11 and retains any entrained foil flakes 129 in the bed 149.

In the lower mixing zone M2 there leads at least one lower granulate feed 152, for example in the form of at least one graunlate passage aperture 118, formed in the wall of the fall shaft 11,through which granulate particles from the bed 149 can enter the mixing zone M2 and combine there with the premixture formed in M' to give a mechanically stabilized, virtually uniform feed stream of disintegrated sheet waste and thermoplastics granulate for the extruder 100. This mechanical stabilizing of the mixture is probably partly based upon the fact that the sheet flakes 129, even at the end of mixing zone M', are at least fixed sufficiently in the continually forming premixture bed by the granulate particles 169 and the movable matrix formed by them that segregation phenomena do not substantially occur.

As a result, the sheet flakes 129 contained in the premixture have substantially lost their freedom of movement when they enter the mixing zone M2 as a consequence of the "hail effect" of the granulate particles 169 quite suddenly and to the extent that they enter the premixture bed. It will be understood that the quantity of granulate particles 169 fed for this purpose per unit time into the mixing zone M' slhould be large enough to ensure that an excess of sheet flakes 129 in the resultant premixture bed is avoided.

A defined boundary between the lower end of the upper mixing zone M' and the upper end of the lower mixing zone M2 cannot in general be identified; the transition is rather dependent upon the particular operating conditions and feed rates and it is not of practical importance whether the contin ualiy forming bed of premixture is considered as the lower end of the upper mixing zone M' or as the upper end of the lower mixing zone M2.

The mixing operating of importance for mixing zone M2 consists in the continuous combining of the premixture with the second granulate partial stream which supplies the remaining granulate component of the feed stream; preferably, the bed of premixture forms an upper cover of mixing zone M2 or an overlying layer, the thickness of which can be controlled with the help of the current feed rates (first granulate stream, flake stream, second granulate stream).

With many normal operating conditions (a typical rate of occurrence of sheet waste with continuous production of typically less than 10% by weight, e.g. approx. 5% by wt.), it is sufficient to carry out the control of the granulate feed into the lower mixing zone M2 only by way of the control of the granulate feed into the upper mixing zone M1, so that although the rate of feed of granulate at the upper granulate feed 151 is made variable or continually adjustable to the process operation, the rate of granulate feed through the lower granulate feed point 152 is maintained virtually constant.

For a corresponding regulation in the plant according to Fig. 1, therefore, the actuation of the slide valve 163 is usually sufficient for a more or less large proportion of the granulate fraction to the total mixture entering at 151 and a control of the lower granulate feed point 152 is not necessary.

As a control parameter for the valve 163, for example, the optically measured density of the stream of sheet flakes 129 entering the fall shaft 11 can be used. Alternatively or in complementary manner, the height of the bed which forms in the second, relatively static mixing zone M2 may also be monitored, since an excessive rise in this level could lead to the first mixing zone M' being displaced by the second mixing zone M2, i.e. being filled and thereby the formation of a mechanically stabilized mixture being rendered difficult or impossible.

If, therefore, under given operating conditions, the possibility exists of the dynamic mixing zone M' being filled up by an ascending bed of the mixing zone M2, a corresponding sensor in mixing zone M' can appropriately throttle the feed rates, e.g. via the slide valve 163.

With the preferred bulk density ratio for granulate:sheet flakes of 4:1 to 6:1, with a normal feed rate of sheet waste of up to 10% by wt, the bulk volume ratio of granulate:sheet waste is always greater than 1, so that a control of the sheet waste stream in general is not required. If necessary, the hail impact effect of the granulate particles in mixing zone M' can be amplified by strengthening the air stream which introduces the sheet flakes into the fall shaft 11 and thereby increasing the capacity for increased proportions of sheet flakes when necessary.

The upper granulate vessel 16 shown funnelshaped in Fig. 1 has, in addition to the first granulate line 161 which supplies the mixing zone M' with granulate, a second granulate line 162, which supplies with granulate the machine hopper 14 and the granulate bed 149 situated therein and acts in the manner of a filter and feed amplifier. The position of the outlet of the granulate line 162 in the machine hopper 14 is favourably so selected that the desired height of the bed 149 (in particular sufficiently high above the air passage openings 114) is automatically adjusted when the granulate vessel 16 is filled. Monitoring of the granulate supply can then be limited to the granulate vessel 16.

The disintegrating apparatus 120 can be a standard commercial knife mill or similarly-acting beating or cutting installation for disintegrating the sheet waste and is advantageously selected according to the particular form of waste (strips, bands, sheets) to be disintegrated; the preferred form of the particles of disintegrated sheet waste arises from (a) the normal density of the usual thermoplastics masses (0.1 -1), (b) the desired bulk density of the flakes, usually preferably below 0.1, and (c) the desired size ratio.of granulate to flake material.The maximum dimensions (e.g. determined as sieve numbers) of the flakes should in general be not more than three times as large as the maximum dimensions of the granulate particles; typically, the largest area dimensions being on average at most twice as large as the largest granulate dimensions; preferably, the largest area dimensions are on average approximately the same size as the largest granulate dimensions. A substantially more intense disintegration of flakes, i.e. maximum flake dimensions having smaller average values, is possible but in general does not result in further advantages.

The apparatus 10 illustrated in Fig. 1 and the plant 100 respectively makes possible substantially trouble-free and economic recycling of thermoplastics sheet waste; construction and operation of the apparatus are simple and economic; typically, with an additional energy consumption of approximately 10 kW per hour, the waste produced by a sheet manufacturing plant with edge trimming can be recovered virtually without loss, and virtually without problems of dust accumulation and thermal breakdown.

The thermoplastics feed stream produced according to Fig. 1 preferably forms a material cover lying directly on the extruder screw 102 and is thoroughly mixed by the action of the extruder screw 102 and screw thread, as indicated in Fig. 1 by arrows in the designated screw mixing zone 19.

The revolving screw thread 104 can produce a more or less pronounced circulation and additional homogenization of the feed stream, in that it draws a portion thereof into the extruder, compacts it there and converts it into the plastic state as indicated cross-hatched in the plasticizing zone 109, and expels it at the outlet end (not shown) of the extruder; another part of the feed stream is circulated by the screw thread 104 in the direction of the arrows in the screw mixing zone 19.

Fig. 2a shows in a schematic, cut-away sectional view the two mixing zones Ma, M2 of an apparatus 20 according to this invention, the start of the mixing zone M' (outlet of upper granulate feed line) being omitted and the falling granulate particles 269 and flakes 229 illustrated respectively by cir cles and squares not being drawn in the middle portion; also, the density of the particles and flakes in the region of the screw mixing zone 29 is not in accordance with reality, since the screw thread 204 of the screw 202 increasingly compacts the particles of the feed stream.

The fall shaft 21 consists of a shaft upper part 210 which is inserted into the shaft lower part 211.

The lower part 211 has, in each side wall, two air openings 213, 214; 215, 216, each of which is covered by a strip 223, 224; 225, 226, so that the air flowing downwards in the fall shaft 21 can escape through the granulate bed 249 (only partly shown) in the direction of the arrows, whereas the granulate particles for their part cannot pass through the air openings into the fall shaft 21.

The premixture formed in mixing zone M' accumulates as a slowly downwardly flowing material bed in mixing zone M2 and is there mixed with additionai granulate from the bed 249, which can enter the mixing zone M2 from the machine hopper 24 through a granulate opening 221, 222; 223, 224 in each wall of the fall shaft lower part. The opening 222 in the front wall is not shown.

The mechanically stabilized mixture comprising the flakes 229, the granulate particles 269 of the first granulate stream which fall in a hail-like manner and the granulate particles sliding from the bed 249, is moved as explained above by the action of the revolving screw thread 204 in the screw mixing zone 29 in the direction of the arrows and thereby additionally mixed.

Fig. 2b shows the apparatus 20 in Section A-A of Fig. 2a, the flakes and the granulate particles being indicated schematically only in the region of the screw mixing zone 29, in order to illustrate the cir culation of material occurring also in the axial di rection before being drawn into the extruder 200.

The invention is not limited to the recycling of sheet wastes from sheet manufacture. Indeed, thermoplastics sheet waste produced in the proc essing.of plastics foils, e.g. in the textile or packag ing industries or in other processes, can also be produced according to this invention. As preferred examples of typical thermoplastics sheet or foil wastes, mention may be made of wastes of homo polymeric or copolymeric polyolefins, such as plyethylenes of various types, also copolymers of ethylene and acrylic acid and other thermoplastics polymer materials having similar extrusion proper ties.

Claims (14)

1. A process for the recyling of thermoplastics waste into a thermoplastics process, in which the non-regenerated plastics waste, such as sheet waste, is introduced into an extruder continuously supplied with thermoplastics granulate in which the plastics waste is disintegrated to particlate form of relatively low bulk density, a mechanically stabilized, virtually uniform feed stream is formed from the disintegrated waste and thermoplastics granulate of relatively high bulk density and the feed stream is introduced into the extruder.

2. A process according to claim 1, in which the disintegrated waste, is combined in a falling stream with a first granulate partial stream to give a premixture, which is then combined with a second granulate partial stream to give the stabilized feed stream.

3. A process according to claim 1 or 2, in which the waste is mechanically processed to form flakes.

4. A process according to claim 3, in which the waste is mechanically processed in a mill.

5. A process according to claim 1, 2, 3 or 4, in which the disintegrated waste, such as flakes combined in a falling air stream with the first granulate partial stream to form a premixture and an air stream is conducted, after or during the formation of the stabilized feed stream, through a bed of the thermoplastics granulate, in order to free the air stream virtually completely of disintegrated waste.

6. A process according to any one of claims 1 to 5, in which the feed stream forms, in the feed opening of the extruder, a material cover lying on the extruder screw, which is mixed by the screw thread before being drawn into the extrusion cylindet.

7. A process according to any one of claims 1 to 6, in which the bulk density of the granulate is at least three times as large as the bulk density of the disintegrated waste and that the largest particle dimensions of the latter on the average are at most three times as large as those of the former.

8. A process for the recycling of thermoplastics waste substantially as hereinbefore described.

9. Apparatus for producing a substantially uniform stream of thermoplastics granulate and thermoplastics pieces, such as flakes suitable for direct feeding into an extruder, comprising a fall shaft having an upper end for connection to a source for the thermoplastic pieces such as flakes and a lower end for connection to a feed opening of an extruder, a machine hopper which surrounds the fall shaft near its lower end, an upper granulate feed and a lower granulate feed leading into the fall shaft in order to form, between the two granulate feeds an upper mixing zone (M') for producing a falling stream of a granulate/pieces such as flakes premixture and to form, at the lower granulate feed, a lower mixing zone (M2) for producing a particle bed, in which the premixture is continually combined with granulate from the lower granulate feed and is conducted as feed into the extruder.

10. Apparatus according to claim 9, comprising an upper granulate funnel, from which a first granulate line leads to the upper granulate feed and a second granulate line leads to the machine hopper.

11. Apparatus according to claim 9 or 10, in which the machine hopper which surrounds the lower portion of the fall shaft possesses at least one granulate opening which forms the lower granulate feed, and at least one air outlet opening, which opening opens out into the portion of the machine hopper which is intended to receive an outer granulate bed surrounding the lower portion of the fall shaft, which outer granulate bed supplies the lower mixing zone (M2) with granulate and serves as a filter for thermoplastics pieces such as flakes.

12. Apparatus according to any one of claims 9 to 11, comprising an apparatus for disintegrating sheet material to form sheet flakes, which apparatus is connected to the upper end of the fall shaft.

13. Apparatus according to claim 12, in which the disintegrating apparatus is connected to the upper end of the fall shaft by way of a blower and a cyclone.

14. Apparatus for producing a substantially uniform stream of thermoplastics granulate and thermoplastics pieces such as flakes, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.