WO1996031332A1

WO1996031332A1 - Method and plant for separating polyolefins from waste containing same

Info

Publication number: WO1996031332A1
Application number: PCT/FR1996/000519
Authority: WO
Inventors: Michel Filippelli
Original assignee: Michel Filippelli
Priority date: 1995-04-07
Filing date: 1996-04-05
Publication date: 1996-10-10
Also published as: FR2732686B1; FR2732686A1; AU5504396A

Abstract

A method for separating polyolefins from waste containing same, wherein said waste is selectively melted by contacting it with an intermediate heat transfer fluid and the resulting mixture is vacuum distilled to remove the polyolefins, is disclosed. A plant comprising a melter (1), means (2, 3) for feeding the waste into the melter (1), a source of heat transfer fluid (12), means (14) for delivering the heat transfer fluid from the source (12) to the melter (1), a distillation column (17) connected to the melter, and means (18, C3) for feeding the mixture of the molten polyolefins and the heat transfer fluid to said distillation column where the polyolefins are separated from said heat transfer fluid, is also disclosed.

Description

Process and installation for the separation of polyolefins contained in waste-

The present invention relates to a process and an installation for the separation and recovery of the polyolefins contained in waste of various origins (industrial waste, distribution waste such as drums and cans, household waste such as bottles, pots, flasks and the like, plastic waste from building and public works, waste from the automobile and from the industrial parts sector, waste from the agricultural sector, etc.), i.e. from all discarded and manufactured objects , at least in part, in a plastic material of the aforementioned family such as, for example, polyethylenes, polypropylenes, etc. The separation and recovery of the polyolefins contained in the waste is generally carried out by means of physical-mechanical recycling facilities and processes which implement a certain number of operations and materials such as, for example: - sorting waste manual for removing objects containing polyolefins;

- manual removal of foreign bodies remaining attached to the objects (for example: metal bottle caps), and, possibly, washing of the latter; - grinding of objects by means of a mechanical grinder;

- regeneration carried out by introducing sorted and crushed waste into an extruder in order to obtain, between 140 and 250 degrees C, a mixture in the molten state which can then be used to manufacture various products, for example by molding by low pressure extrusion or injection-compression.

These physico-mechanical recycling methods and installations for waste have many drawbacks: - they require manual sorting and fine grinding of waste;

- they require the use of extruders demanding a lot maintenance, due to the presence of undesirable elements, forgotten by sorting or not eliminated during the water wash; these inert elements are generally the main cause of mechanical weakness and inconsistency of the characterization results;

- they do not allow good dispersion of the fillers, stabilizers and dyes in the mixture melted by the extruder, due to the short residence time specific to these machines; - they generate a high rate of volatiles in the final products, by a sharp rise in temperature, very localized and difficult to control;

- They have no selectivity to recy¬ cler waste very soui llés or made of different nested materials that will not be isolated or refused;

- they do not allow the recycling of particularly burnt industrial products (rheological separation);

- they consume a lot of energy, so that the economic balance can be negative compared to an energy recovery of waste, by incineration.

The object of the invention is in particular to remedy these drawbacks.

According to the invention, this objective is achieved by a process and an installation according to which the polyolefin-based wastes are selectively melted by contact with an intermediate heat transfer fluid brought to a temperature higher than the final melting temperature Tf polyolefins, that is, for example, Tf + 50 degrees C, and lower than the chemical degradation temperature of the polyolefins, and the mixture resulting from this selective melting is then subjected to vacuum distillation effecting the separation of its constituents and allowing the extraction, in the lower part, of said molten polyolefins.

The method and the installation according to the invention provide numerous advantages:

- they do not require any manual sorting or shredding of waste;

- they do not use extruders for melting-gelling of recycled plastic; - They allow good dispersion of the fillers, stabilizers and dyes which can be easily mixed by kneading, with the product extracted, at the bottom of the vacuum extraction column, advantageously useful for the distillation process.

- they generate a low measurable rate of volatiles in the final products;

- they have a selectivity allowing the recycling of very soiled waste (floors, detergents, hydrocarbons, domestic waste, etc.) or very nested (electric cables, automotive parts, mixtures of polyolefins and other plastics, etc. .);

- they allow the recycling of particularly burnt industrial products which do not react like polyolefins (at low melting point);

- They consume less energy, in particular by the absence of use of an extruder and by the possible re-use of volatiles as heating fuels.

The aims, characteristics and advantages above, and others still, will emerge more clearly from the description which follows and from the appended drawings in which:

FIG. 1 is a schematic representation of an exemplary embodiment of an installation for the separation of polyolefins contained in waste, by selective fusion using an intermediate heat transfer fluid. Figure 2 is a schematic view, on a larger scale, of the melting device of this installation.

Reference is made to said drawings to describe advantageous examples, although in no way limitative, of implementation of the method and production of the polyolefin-based waste recycling installation according to the invention. This installation mainly includes:

- A crucible or melter 1 consisting of a large tank or large capacity; - means allowing the introduction of polyolefin-based waste into this tank, and extracting the unfounded;

- a source of heat transfer fluid intended to serve as an intermediate thermal vector; - Means for bringing this heat transfer fluid into said tank;

- a device for distilling the polyolefin / heat transfer fluid mixture connected to the tank, in order to extract the polyolefins.

The tank 1 is open at its upper part and it can be fitted, internally, with all the devices necessary for the proper functioning of the installation, such as temperature sensor, hydrometer, vi scos met re, agitator, etc.

The means for introducing the waste into the crucible or melter 1 can be of two kinds, depending on whether it is bulky waste or waste of small dimensions. According to a characteristic arrangement of the invention, the means used for the introduction of waste rich in polyolefins into the crucible or melter 1, also serve for the retention and evacuation of heavy and light undesirable, as explained in following this presentation. For bulky waste (industrial waste, automobile parts, etc.), the introduction means may consist of one or more large baskets or skeleton containers 2, the vertical movements of which can be obtained by a vertical lifting of the hoist type (not shown), or by lower thrust by means of one or more jacks. These filtering cells 2 pass through airlocks for their loading and the inerting of the operation.

For waste of small dimensions (crushed containers, drums, pots, etc.), the introduction means can advantageously consist of at least one linear conveyor 3 with discs or squeegees, the general construction and operation of which are known in itself, but which is arranged specifically for its use, in a particular way, according to a characteristic arrangement of the invention, to enable it to perform the multiple functions which are assigned to it. This conveyor or each of the conveyors 3 comprises a fixed structure comprising a tube 4 constituted in a closed loop and in which the drive disks or scrapers 5 move, only a few of which are shown at the top of the conveyor.

These drive discs are connected by a chain and their movement inside the tube 4 is obtained by means of a motor 6, preferably at variable speed, ensuring the rotation of a wheel provided with fingers. drive 7 and arranged inside a curved section 4a of the tube 4. The tube 4 constituting the fixed structure of the conveyor 3 or of each conveyor 3, and in which the drive disks or squeegees 5 circulate, may have a diameter of the order of 250 mm and includes:

- An upper horizontal or substantially horizontal section 4b, disposed above the melter 1 and comprising an upper opening 8 into which opens a hopper 9, vibrated or not, making it possible to introduce your waste to be treated, into the conveyor;

- A section 4c descending towards the melter 1 and which can advantageously have a vertical or substantially vertical orientation; interestingly, this section 4c can be equipped, externally, with a heating device 24 allowing preheating of the waste, when it passes through said non-submerged section, before it enters the melter 1;

- A curved section 4d housed in the melter 1 and which can have the shape of a U whose two opposite branches are arranged near the vertical walls of said melter 1 and whose lower section is placed near the bottom of the latter;

- an ascending section 4e preferably oriented vertically or substantially vertically, which can be equipped, externally, with a cooling device (not shown); - a horizontal or substantially horizontal section 4f connecting to the previous one by a curved section and provided with a lower unloading opening 10 for heavy swabs and products which have not reacted during their stay in the heat transfer fluid, and,

- The semi-circular section 4a connecting the lower 4f and upper 4b horizontal sections, this half-ci reu lai re section having a slot 11 extending along its surface oriented in the direction of the loop formed by the conveyor , for the passage of the radial fingers 7 of the wheel 7a for driving the discs 5 of said conveyor.

The section 4d housed in the melter is openwork over at least most of its submerged length, so that the interior of the part of the tube 4 housed in the melter 1 communicates with the interior thereof. . The skeleton section 4d may be constituted by a succession of cylindrical cages assembled one after the other or may comprise a plurality of side openings otherwise formed, these openings however preferably being constituted by longitudinal slots 4d " , which, like those in baskets 2, can have a width of the order of 1 to 1.5 mm.

The movable members 5 of the conveyor 3 move in the fixed tubular structure 4 of the latter, at a slow, adjustable speed, which can be, for example, between 0.5 and 3 m / min.

The installation according to the invention also comprises a source of heat-transfer fluid which may advantageously consist of a white hydrogenated non-aromatic petroleum product, with a flash point equal to or greater than 200 degrees C, with an atmospheric distillation interval ( 280-315 degrees C) and density at 15 degrees C between 0.75 and 0.9. These products are preferably made up of hydrogenated white hues, colorless and i nodorous.

The source of heat transfer fluid may advantageously be constituted by a heat exchanger 12 arranged, in a manner known per se, to allow heating and circulation of said fluid, from an inlet 12a to an outlet 12b, single-pipe and single-pass at temperature regulated.

The calorie intake source is, for example, constituted by a primary oil circuit, heated by any suitable means and in particular as indicated below.

According to another characteristic arrangement of the invention, the heat transfer fluid is heated by recycling through the heat exchanger 12.

The heat transfer fluid from the heat exchanger 12, via a conduit C1 is introduced into the upper part of the melter 1, for example by means of feed ramps 13, or nozzles distributing the fluid. in the most efficient way to heat the plastic introduced into said melter.

On the other hand, the mixture of molten polyolefins and heat transfer fluid is recovered at the bottom of the melter 1 and conveyed to the exchanger 12, by means of a conduit C2 on which a pump 14 is arranged, preferably of the volumetric type with gears.

This pump 14 circulates the polyolefin / f coolant mixture from the outlet to the inlet of the melter 1, passing through the heat exchanger 12.

Between the outlet 1a provided in the bottom of the melter 1 and the pump 14, a mixer 15 is arranged, the function of which is to improve the overall fluidity of the melted polyolefin / heat transfer mixture. The pump 14 and the mixer 15 can advantageously be grouped into a single mixer-pump assembly.

In order to improve the performance of the installation by limiting the heat loss, the tank 1 can be heated externally, by any suitable heating system (not shown), for example arranged around said tank.

On the conduit C1 and between the outlet 12b of the heat exchanger 12 and the melter 1, are successively arranged: - a dynamic fi lter 16, for example constituted by a self-cleaning hydrocyclone at 0.3 mm, making it possible to choose preferably a mixture richer in denser polyolefins; - an output connected to a C3 conduit connecting

The hydrocyc Lone 16 has a vacuum separation column 17.

On the conduit or connection C3 is arranged a positive displacement pump 18, advantageously constituted by a sampling system on hydrocyclone; thus the oil-rich phase is mainly recirculated.

The vacuum separation column can be constituted by a distillation column with inclined perforated plates, known per se and operating, for example under absolute vacuum of 0.5 bar.

The mixture of molten polyolefin liquid / heat transfer fluid is introduced into the lower half-part of the column to which the conduit C3 terminates. At the level of the introduction of this mixture, a device (not shown) can be provided allowing atomization by steam or by a mixture of steam and nitrogen (HO / N), for very good dehydration of plastic material atomized into spherules 50 to 300 μ in diameter.

The polyolefin mixture is recovered at the base of column 17, while the heat transfer fluid used for the simple and selective melting of waste is removed at the top of said column.

The bottom mixture acts as a non-Newtonian fluid which is itself again separated from the undesirable residual volatile fraction (rewinding) by a mechanical member heating it by programmed friction.

In the lower part of the vacuum separation column 17, is arranged a rotary screw device 25, single or double, but preferably single, with vertical axis and driven in rotation by a motor 26, for example placed below said column. This rotary screw placed in the center of an annular vacuum chamber 27, allows a final kneading and heating (reboiling) of the mixture of polyolefins, that is to say a final devolati Li sati on of said mixture at 250 degrees C, under absolute vacuum of 0.5-0.7 bar.

The rotary screw device 25 serves at the same time for the devolati Li sat i on further than in the column, while ensuring a hydraulic seal with the column. On the other hand, the rotary screw 25 conveys the product outside the column, in the pasty state, cooled or hot.

Advantageously, the heat exchanger 12 can be arranged around the lower part of the vacuum column 17 for recovering the polyolefins where the devolatilization screw 25 is placed, so as to ensure constant and regular heat around said screw.

At the base of the column and outside of it, is advantageously installed a kneading device 19 comprising, at one of its ends, an inlet or hopper 20, which can be provided with a screw, for the introduction of make-up resins, fillers, additives, dyes, etc., in the central part 28, a gelling zone of the resin, and, at its other end, a pressure-increasing zone comprising, for example, a pump 21 with gears or with a granulation or injection screw of the plastic mixture obtained.

The heat transfer fluid removed at the top of the column 17 is conveyed, via a conduit C4, in a recovery exchanger 22 provided with an exhaust 23 for the evacuation of the undesirable gases intended to be burned. Interestingly, these gases are burned in a recovery oven (not shown) used for heating the oil in the primary circuit of the heat-exchanger 12 through which calories are supplied. necessary for the heat transfer fluid.

On the other hand, the outlet of the recovery exchanger 22 communicates with the inlet of the mixer 15, via a conduit C5, in order to return the heat transfer oil devolat i Li sée. The recovery exchanger 22 also makes it possible to control the initial boiling point of the recycled heat transfer fluid, and thus to avoid boiling and the production of foam in the melter 1. According to the process of the invention, the rich waste in polyolefins are selectively melted by a heat transfer fluid of narrow cut serving only as an intermediate vector and brought to a temperature above final melting temperature Tf of the polyolefins, ie, for example Tf + 50 degrees C, and lower than the chemical degradation temperature of the polymer (polyoLéfi molecule or that), for example at a temperature below 300 degrees C, and the mixture weakly miscible resulting from this fusion is then, preferably after hydrocyc ionic filtration, subjected to vacuum distillation achieving the separation of its constituents and allowing, at the bottom, the extraction of molten polyolefins. According to the mode of implementation by means of the installation described above, the waste rich in polyolefins is introduced, by means of the skeleton basket (s) 2 or by the intermediary of the skeleton conveyor (s) 3, in the bath contained in the crucible or melter 1, this bath having a temperature higher than the final melting temperature of the mixture of polyolefins to be extracted, this temperature being for example: Tf + 50 degrees C, in which "Tf" is the final melting temperature of the polyolefin mixture to be extracted _* As indicated above. The heat transfer fluid is heated by recycling through the heat exchanger 12 and rotates in circles on the melter, at a constant flow rate measured by the pump 14, corresponding to the thermal load necessary to melt the solid mass of polyolefins, the temperatures of which melting are equal to or preferably lower than that of the bath introduced into the melter 1, these melting temperatures being for example of the order of 30 to 70 degrees C than that of said bath. According to the operating process of the installation of the invention using one or more conveyors 3, the waste is introduced into the conveyor 3, or into each conveyor, through the hopper 9 and the opening 8, and conveyed to Slow speed, by the drive discs 5 of said conveyor 3 to the lower skeleton section 4d of the latter housed in the melter 1. The polyolefins are melted in contact with the bath contained in the melter 1 and flow in said bath, through the openings 4d 'of said section 4d. The unfounded Heavy (glass, metal, thermoset plastics or with a high melting point, etc.) are raised in the direction of sections 4e and 4f of the conveyor 3 pushed by the drive discs 5 and, When they arrive in the region of the opening 10, they fall, by gravity, into a recovery bucket (not shown) arranged below said opening.

The light unsealed (wood, paper, etc.) which can escape from the light tube 4d and are suspended in the bath contained in the melter 1, and on the surface of which they can float, are extracted by the baskets immersed in said melter and which thus fulfill the function of writers.

The skeleton containers make it possible to retain and evacuate the unfolded continuously (conveyor 3) or discontinuous (basket 2) in a level of melting temperatures Slightly higher than the melting temperature (Tf) of polyolefins, for example : Tf + 50 degrees C.

The fine and dense unfused are extracted by means of the hydrocyclone 16 disposed between the outlet of the polyolefin / heat transfer fluid mixture and the reintroduction of this heated mixture, in the melter 1.

The content of the bath is gradually enriched with polyolefins. The concentration control can be operated by means of a hydrometer housed in the melter 1, by measuring the differential pressure in the bottom of the melter 1, at a fixed level, while controlling the pressure drop at the inlet and at the outlet of the heat exchanger 12.

The desired concentration of polyolefins is maintained by withdrawing the mixture by means of the connection C3 and the pump 18, and by reinjection, in the heat transfer fluid circuit, of the desirable quantity of purified heat transfer fluid withdrawn at the upper part of the separation column 17 which makes it possible to recover 100% of the fraction of end point of atmospheric boiling point (280-315 degrees C) and to extract, at the bottom of the column, as indicated above, The desired mixture of purified polyolefins, unless 0.5% by weight of soluble oil molecules during hexa ne test.

The hydrocyc Lone 16 makes it possible to concentrate the polyolefins, before distillation of the molten mixture between 150 and 250 degrees C. Only a fraction very enriched in polyolefins is extracted from the recycling loop by the pump 18 associated with the hydrocyc Lone 16, the remains returning to the fund r.

The fraction of heat transfer fluid mixture enriched in polyolefins, taken from the recycling loop is atomized, at the level of its introduction into the vacuum separation column 17, as indicated previously, in a nozzle known per se, by steam of water superheated to about 180-200 degrees C, at a pressure of the order of 5 bars, the proportion of working fluid being, for example, at a rate of 2 to 4% by weight of the mixture introduced.

Steam ^superheated promotes The evaporat ion of the heat transfer fluid selected section (azeotrope low-di st i L Lat ion). On the other hand, in addition to the superheated water vapor, nitrogen can be introduced via the same nozzle, or through another inlet orifice, to control the vacuum level.

The residence time of the polyolefins in the melter is several minutes (for example 15 to 45 minutes) to obtain a regular statically homogeneous mixture, in particular in the case of recycling of plastics from urban public landfills. This homogeneous mixture is very easy to use on processing machines such as mold injection and IF (melt flow index) extruders ranging from 0.6 to 7 grams t 1 gram; it being understood that this process makes it possible to remain at 1 gram IF desired by monitoring and statistical mixing of the sources of waste or by correction, at the end of the process, by adding make-up resins to the device 19-20-21.

According to the process of the invention, the quantity of heat transfer fluid is kept constant and the density of this fluid in the melter as well as the pressure drop hydraulically through the exchanger-heater 12, provide information on the excess of polyolefins to be continuously extracted by transfer under vacuum to the separation column, which therefore makes it possible to increase the value of the flow rate of the pump 18.

Claims

1. - Process for the separation of polyolefins contained in waste, characterized in that said waste rich in polyolefins is selectively melted by contact with an intermediate heat transfer fluid brought to a temperature higher than the final melting temperature (Tf) of polyolefins and lower at the chemical degradation temperature of said polyolefins, and the mixture resulting from this selective melting is then subjected to vacuum distillation achieving the separation of its constituents and allowing, at the bottom, the extraction of molten polyolefins.

2. - Method according to claim 1, characterized in that The contacting of waste rich in polyolefins and of the heat transfer fluid is carried out in a skeleton container (2, 4) immersed in a bath of heat transfer fluid, so as to obtain a liquid mixture of molten polyolefins and of heat-transfer fluid, while making it possible to retain and evacuate the melts.

3. - Method according to the claim on 1, characterized in that the distillation is carried out by means of a separation column (17) for recovery, in the lower part. The polyolefins extracted from the mixture and, in the upper part, the heat transfer fluid used for melting waste.

4. - Method according to any one of claims 1 to 3, characterized in that the heat transfer fluid and / or the fluid mixture ca loporteur / po Lyo léfi born molten, is recovered at the bottom of the melter (1) and reintroduced à The upper part of the latter after passing through a heat exchanger (12).

5. - Method according to claim 4, characterized in that retains the fine and dense unfunded by means of a hydrocyclone (16) disposed between the outlet of the mixture po lyo léfi nes / f It coolant and the reintroduction of this heated mixture in the melter (1).

6. - Method according to any one of claims 1 to 5, characterized in that one uses a hydrocyclone (16) disposed between the outlet of the polyolefin mixture / heat transfer fluid and the reintroduction of this heated mixture, the melter (1), to concentrate the polyolefins, before distillation of the molten mixture between 150 and 250 degrees C.

7. - Method according to one of claims 5 or 6, characterized in that the purified heat transfer fluid removed from the upper part of the separation column (17) is reinjected into the recycling loop (1, C2, 12, C1 , 1) between the melter (1) and the heat exchanger (12).

8. - Method according to claim 7, characterized in that the heat transfer fluid is reinjected between the melter (1) and a laxeur (15).

9. - Method according to one of claims 7 or 8, characterized in that the purified heat transfer fluid removed from the upper part of the separation column (17), passes through a recovery exchanger (22), before its reinjection into the recycling loop (1, C2, 12, C1, 1), and in that the recovered gases are preferably used for heating the oil in the primary circuit of the exchanger (12) providing the necessary calories with heat transfer fluid.

10. - Method according to any one of claims 1 to 9, characterized in that the heat transfer fluid is a white hydrogenated petroleum product, flash point greater than or equal to 200 degrees C.

11. - Method according to any one of claims 1 10, characterized in that the mixture enriched with polyolefins and heat transfer fluid is atomized in a nozzle, at the level of its introduction into the column of separation under vacuum (17), by superheated steam, for example, at a rate of 2 to 4% by weight of the mixture introduced.

12. - Method according to claim 11, characterized in that nitrogen is also introduced into the vacuum separation column (17) by said nozzle or by another inlet orifice.

13. - Installation for separating polyolefins contained in waste, characterized in that it comprises: - a melter (1)

- Means (2, 3) for the introduction of waste rich in polyolefins in this melter (1);

- a source of heat transfer fluid (12);

- Means (14) for conveying the heat transfer fluid, from the source (12) to the melter (1);

- Means (2, 3) for the retention and evacuation of the undead;

- a distillation column (17) connected to said melter (1);

- Means (18, C3) for conveying the mixture of molten polyolefins / heat transfer fluid to said distillation column where the polyolefins and said heat transfer fluid are separated.

14. - Installation according to claim 13, characterized in that the means (2, 3) for the introduction of waste rich in polyolefins into the melter (1) also constitute the means for bringing the waste into contact with the heat transfer fluid and the means of retention and evacuation of the flooded.

15. - Installation according to claim 14, characterized in that the means for introducing waste, in particular bulky waste, into the melter (1), consist of at least one basket or skeleton container (2) , for example suspended from a device allowing it to be moved vertically.

16. - Installation according to claim 14, characterized in that the means making it possible to introduce waste, in particular small waste, into the melter (1), are constituted by at least one conveyor (3) comprising a tube ( 4) constituted in a closed loop and in which the mobile members of said conveyor (3) move, for example constituted by discs (5) connected by chains, this tube comprising:

- An upper section (4b) horizontal or substantially horizontal disposed above the melter (1) and having an upper opening (8) for the introduction of waste;

- a section (4c) descending towards the melter (1);

- a curved section (4d) housed in the melter (1) and the lateral surface of which is provided with a plurality of openings or slots (4d ');

- A horizontal or substantially horizontal section (4f) provided with a lower unloading opening (10) and connecting to the upper horizontal section (4b) via a curved section (4a).

17. - Installation according to claim 16, characterized in that the means for driving the movable members (5) of the conveyor (3) are housed inside the curve formed by the curved section (4a) connecting the horizontal sections lower (4f) and upper (4b) of the fixed tubular structure (4) of said conveyor, these means comprising a motor (6) with variable speed, driving a paddle wheel or drive fingers (7) the end parts of which can moving through a slot (11) extending along the internal surface of said curved section (4a).

18. - Installation according to claim 16, characterized in that the descending section (4c) not immersed in the conveyor (3) is equipped, externally, with a heating device (24).

19. - Installation according to claim 13, characterized in that the source of heat transfer fluid is constituted by a heat exchanger (12).

20. - Installation according to claim 19 characterized in that the outlet of the melter (1) is connected to the heat exchanger (12).

21. - Installation according to one of claims 19 or 20, characterized in that a mixer (15) is disposed between the outlet of the melter (1) and the means (14, 18) for conveying the mixture po Lyolefins / f Him coolant in the direction of the separation column.

22. - Installation according to claim 19, characterized in that a hydrocyclone filter (16) is disposed on the conduit (C1) conveying the coolant or the mixture of lyo léfi nes / f coolant, the heat exchanger heat (12) to the melt (1).

23. - Installation according to claim 22, characterized in that it comprises a connection (C3) connected to the hydrocyclone filter (16), disposed on the conduit (C1) conveying the mixture poLyolefin born / f Him coolant, l 'heat exchanger (12) at the melter (1), this connection (C3) connecting said conduit (CD to the separation column under vi of (17).

24. - Installation according to claim 23, characterized in that a positive displacement pump (18) is mounted on the connection (C3).

25. - Installation according to claim 20, characterized in that the upper part of the separation column (17) is connected to the outlet of the melter (1) by means of a pipe (C4-C5).

26. - Installation according to claim 25, characterized in that a recovery exchanger (22) provided with an exhaust (23) for the evacuation of undesirable gases, is mounted on the pipe (C4-C5) connecting the part high of the separation column (17) at the outlet of the melter (1).

27. - Installation according to claim 13, characterized in that a rotary screw device (25) with vertical axis is arranged in the lower part of the separation column (17) for final mixing and heating of the mixture of polyolefins .

28. - Installation according to resale cation 27, characterized in that the screw device (25) is used as a means for carrying out a more extensive devolati liation than in the column (17). While ensuring a hydraulic seal with the column.

29. - Installation according to one of claims 27 and 28 according to which the screw (25) conveys the product outside the column in the pasty state cooled or hot.

30. - Installation according to the claims 18 and 27, characterized in that the heat exchanger (12) is arranged around the lower part of the vacuum separation column (17) where the devolatilisa ion screw is located ( 25).

31. - Installation according to the claim on 13, characterized in that a kneading device (19) is installed at the base and outside of the separation column (17), for the reception of the mixture of purified polyolefins, liquid or pasty, extracted at the base of the said column, this device comprising at least one inlet (20) for the possible introduction of corrective resins for lyo-léf i ni ues, fillers, additives or dyes.