EP0784661B1 - Process for recovering synthetic raw materials and fuel components from used or waste plastics - Google Patents

Abstract

PCT No. PCT/EP95/03901 Sec. 371 Date Aug. 15, 1997 Sec. 102(e) Date Aug. 15, 1997 PCT Filed Oct. 2, 1995 PCT Pub. No. WO96/10619 PCT Pub. Date Apr. 11, 1996The invention concerns a process for recovering synthetic raw materials and fluid fuel components from used or waste plastics in accordance with patent application P 43 11 034,7. At least a partial flow of the depolymer produced according to this process is subjected, together with coal, to a coking process, fed to a thermal utilization system or introduced as a reducing agent into a blast furnace process. The depolymer can be used as an additive for bitumen and bituminous products.

Description

The invention relates to a method for obtaining chemical raw materials and / or liquid fuel components made from old or waste plastics where the old or waste plastics at an elevated temperature, possibly with the addition of a liquid Auxiliary phase, a solvent or solvent mixture, depolymerized and the resulting gaseous and condensable depolymerization products (Condensate) as well as a pumpable viscous depolymerization products containing the bottom phase (depolymerized product) is withdrawn in separate substreams and Condensate and depolymerizate are worked up separately as well as the use of a manufactured by this method Depolymerizates.

Such a method is described in DE-A-43 11 034.

1.) Ein Depolymerisat in einer Menge zwischen 15 und 85 Gew.-%, bezogen auf die eingesetzte Kunststoffmischung, das je nach Zusammensetzung und den jeweiligen Erfordernissen in die der Sumpfphasenhydrierung, der Druckvergasung, der Schwelung (Pyrolyse) und/oder anderen Prozessen und Verwendungen zuzuführenden Produktteilströme aufgeteilt werden kann.
Es handelt sich dabei überwiegend um > 480 °C siedende schwere Kohlenwasserstoffe, die alle mit den Alt- und Abfallkunststoffen in den Prozeß eingetragenen Inertstoffe, wie Aluminium-Folien, Pigmente, Füllstoffe, Glasfasern, enthalten.

2.) Ein Kondensat in einer Menge von 10 bis 80, vorzugsweise 20 bis 50 Gew.-%, bezogen auf die eingesetzte Kunststoffmischung, das in einem Bereich zwischen 25 °C und 520 °C siedet und bis zu ca. 1.000 ppm organisch gebundenes Chlor enthalten kann.
Das Kondensat läßt sich z. B. durch Hydrotreating an fest angeordneten handelsüblichen Co-Mo- oder Ni-Mo-Katalysatoren in ein hochwertiges synthetisches Rohöl (Syncrude) umwandeln oder auch direkt in Chlor tolerierende chemisch-technische oder raffinerieübliche Verfahren als kohlenwasserstoffhaltige Basissubstanz einbringen.

3.) Ein Gas in Mengen von etwa 5 bis zu 20 Gew.-% bezogen auf die eingesetzte Kunststoff-Mischung, das neben Methan, Ethan, Propan und Butan auch gasförmige Halogenwasserstoffe, wie hauptsächlich Chlorwasserstoff sowie leichtflüchtige, chlorhaltige Kohlenwasserstoff-Verbindungen enthalten kann.
Der Chlorwasserstoff läßt sich z. B. mit Wasser aus dem Gasstrom zur Gewinnung einer 30 %igen wäßrigen Salzsäure herauswaschen. Das Restgas kann hydrierend in einer Sumpfphasenhydrierung oder in einem Hydrotreater vom organisch gebundenen Chlor befreit und z. B. der Raffineriegas-Verarbeitung zugeführt werden.

The process products of the depolymerization are essentially divided into three main product streams.

1.) A depolymerizate in an amount between 15 and 85 wt .-%, based on the plastic mixture used, which, depending on the composition and the respective requirements in the bottom phase hydrogenation, pressure gasification, smoldering (pyrolysis) and / or other processes and Usage product streams to be used can be divided.
These are predominantly heavy hydrocarbons boiling at> 480 ° C, which contain all inert materials, such as aluminum foils, pigments, fillers, glass fibers, which have been introduced into the process with the waste and waste plastics.

2.) A condensate in an amount of 10 to 80, preferably 20 to 50 wt .-%, based on the plastic mixture used, which boils in a range between 25 ° C and 520 ° C and up to about 1,000 ppm organically bound May contain chlorine.
The condensate can be z. B. by hydrotreating on firmly arranged commercial Co-Mo or Ni-Mo catalysts in a high-quality synthetic crude oil (Syncrude) or also directly in chlorine-tolerant chemical-technical or refining processes as a hydrocarbon-containing base substance.

3.) A gas in amounts of about 5 to 20 wt .-% based on the plastic mixture used, which in addition to methane, ethane, propane and butane can also contain gaseous hydrogen halides, such as mainly hydrogen chloride and volatile, chlorine-containing hydrocarbon compounds .
The hydrogen chloride can, for. B. wash out with water from the gas stream to obtain a 30% aqueous hydrochloric acid. The residual gas can be hydrogenated in a bottom phase hydrogenation or in a hydrotreater from the organically bound chlorine and z. B. the refinery gas processing.

Here the process parameters are preferably chosen so that the highest possible Share of condensate arises.

The individual product streams, especially the condensate, can further processing afterwards in the sense of raw material recycling, e.g. B. used as raw materials for olefin production in ethylene plants.

An advantage of the method is that inorganic Minor components of the old or waste plastics are concentrated in the sump phase be, while the condensate not containing these ingredients in less complex process can be processed. Especially about the optimal one The process parameters temperature and dwell time can be set be that on the one hand a relatively high proportion of condensate is formed and on the other hand the viscous depolymerizate of the bottom phase under the process conditions remains pumpable. A useful approximation can be that an increase the temperature around 10 ° C with an average residence time the yield of the in volatile phase passing products increased by more than 50%. The residence time dependency 6 shows two typical temperatures.

The preferred temperature range for the depolymerization process is 150 to 470 ° C. A range of 250 is particularly suitable up to 450 ° C. The residence time can be 0.1 to 20 hours. As generally sufficient a range of 1 to 10 h has been found. The pressure is less critical Size. So it may be preferable to use the vacuum method perform, e.g. B. if volatile components due to procedural reasons have to be deducted. However, relatively high pressures are practicable, too however, a higher expenditure on equipment. In general, the pressure should be are in the range from 0.01 to 300 bar, in particular 0.1 to 100 bar. The procedure can preferably be good at normal pressure or slightly above z. B. up to about 2 bar perform, which significantly reduces the expenditure on equipment. To the depolymerizate degas as completely as possible and in order to increase the proportion of condensate even more, the process is advantageous with a slight negative pressure down to about 0.2 bar carried out.

The depolymerization can be carried out in a conventional reactor, e.g. B. a stirred tank reactor, be carried out on the appropriate process parameters, such as pressure and temperature is designed. Suitable reactors are in the unpublished German patent applications P 44 17 721.6 and P 44 28 355.5. Preferably, the reactor contents are protected against overheating circulatory system connected to the reactor. This circulatory system in a preferred embodiment comprises an oven / heat exchanger and one powerful pump. The advantage of this method is that high circulation flow through the external furnace / heat exchanger is achieved on the one hand the necessary temperature increase of that in the circulatory system Material remains low, on the other hand favorable transmission conditions in the furnace / Allow heat exchangers to have moderate wall temperatures. This will make local Overheating and thus uncontrolled decomposition and coke formation largely avoided. The heating of the reactor contents is comparatively very gentle.

A high circulation flow can preferably be achieved with powerful centrifugal pumps to reach. However, these, like other sensitive elements of the Circulatory system, the disadvantage that they are susceptible to erosion.

This can be counteracted by withdrawing it into the circulatory system Reactor contents before entering the exhaust line one in the reactor passes through the integrated ascending section, where coarser solid particles with accordingly high rate of descent.

The reactor is designed so that the extraction device for the circulation (circulation system) lies in a riser for the essentially liquid reactor content. By appropriately determining the rate of climb, essentially determined through the dimensioning of the ascent section and the dimensioning of the circulating current, particles with a higher sink rate, which are the cause of the erosion, be kept out of circulation. The Rise path within the reactor can be designed in the form of a tube, which in the is mounted essentially vertically in the reactor (see FIG. 1).

Instead of a pipe, the Riser can also be realized in that a partition in the reactor Segments divided (see Figure 2).

The tube or the partition does not close with the reactor cover, protrude but beyond the fill level. The pipe or partition are far enough from the reactor floor removed that the reactor contents unimpeded and without major turbulence in the ascent can flow in.

The solids are drawn off at the bottom of the reactor together with the amount of depolymerizate that is to be used for further processing. So that the sedimented Inert substances are removed from the reactor as completely as possible the removal device for the depolymerizate preferably in the lower area, especially attached to the bottom of the reactor.

To further support the complete removal of the inert substances, the reactor preferably tapers downward in the bottom area, e.g. B. tapered, or as a standing on its top Cone jacket.

Figure 1 shows such a device in the sense of an embodiment. In reactor (1) from storage container (13) old and waste plastic via addition device (18) by means of a gas-tight metering device (14) z. B. on introduced by pneumatic means. One such metering device is, for example a cellular wheel sluice well suited. The depolymerizate including the contained Inert substances can be removed via device (7) at the bottom of the reactor. The plastic is added and the depolymerized product is removed advantageously continuously and is designed so that approximately a certain Filling level (3) of the reactor content is maintained. The resulting device (4) Gases and condensable products from the top of the reactor deducted. The contents of the reactor are transferred to the circulation system via a discharge line (16) via pump (5) for gentle heating in furnace / heat exchanger (6) and recirculated to reactor (1) via inflow (17). In the reactor (1) tube (20) is vertical arranged, which forms a riser (2) for the reactor recycle stream.

The depolymerization stream withdrawn from the reactor is a factor of 10 to 40 less than the circulating current. This depolymerization stream is z. B. on wet mill (9) driven to the inert components contained therein for further use Bring processing allowable size. The depolymerization stream can also over a further separation device (8), where it is from the inert components is largely exempt. Suitable separation devices are, for example Hydrocyclones or decanters. The inert components (11) can then be separated removed and recycled, for example. Optionally, a part of the wet mill or the separator driven depolymerization stream via a pump (10) back into the reactor to be led back. The rest of the processing is z. B. bottom phase hydrogenation, Smoldering or gasification fed (12). Part of the depolymerizate can be taken directly from the circulatory system via a line (15) and the Further processing can be supplied.

FIG. 2 shows a similarly constructed reactor as in FIG. 1 with the difference that that the ascent section is not formed by a tube, but by a reactor segment, which is separated from the rest of the reactor content by a partition (19) is.

When used and plastics from household collections are used, the Most of the inert components (11) discharged via the separating device (8) made of aluminum, which is a material recycling in this way can be supplied. The removal and recycling of aluminum also opens up the possibility of completely composite packaging to recycle. The recycling can take place together with plastic packaging. This has the advantage that there is no separation of these packaging materials can. Composite packaging usually consists of paper or Cardboard connected with a plastic and / or aluminum foil. In the reactor Liquefied plastic, the paper or cardboard broken down into primary fibers, the follow the liquid because of their low tendency to sedimentation. The aluminum can largely be obtained separately. Plastic and paper are after the depolymerization carried out a raw material recycling.

Figure 3 shows a depolymerization system with two containers, each on different Temperature level can be operated. The first depolymerization tank (28) is equipped, for example, with a stirrer (33) to control the Lock (31) used and waste plastics quickly fed into the present to be able to mix in hot depolymerizate. The downstream second depolymerization tank (1) corresponds to the reactor from Fig. 1. The circuit for gentle Heating up, essentially consisting of pump (5) and furnace / heat exchanger (6) is therefore low in solids. The depolymerizate including the solid components is withdrawn from the bottom of the reactor. The solid / liquid ratio on the removal device (7) of the container (1) between 1: 1 and 1: 1000.

The removal device (7) is preferably a drop section (21) with one for this purpose immediately downstream branch (22), which is essentially at right angles.

Falling section (21) and branch (22) can be designed as a T-shaped tube.

The branch can also be equipped with mechanical separation aids (23) be.

Via branch (22) a stream of organic, under the present conditions derived essentially liquid components of the depolymerizate will. The depolymerizate is conveyed via pump (27) for further processing or can also be returned at least partially via line (32) to reactor (1).

The amount derived can be up to a thousand times the amount of solids discharged be. In extreme cases and temporarily if necessary, nothing can be said about Branch (22) can be derived. By determining the via branch (22) deducted amount of depolymerizate can suitable flow conditions for the safe discharge of the solids can be guaranteed. At the same time, the Derived current should be such that solid particles are not as significant as possible Scope to be swept away. The ratio is preferably from discharged amount of solids to the derived amount 1:50 and 1:200.

Falling section (21) or the downspout is in a special embodiment at the bottom Provide a lock (24) at the end. Above this lock is an addition device (25) attached for flushing oil.

Figure 5 shows a procedural alternative, in which the drop section (21) Separating device (26) is connected directly downstream. There is preferably an addition device on this (25) attached for flushing oil.

Rinsing oil with a higher density than that of the depolymerizate is added via the addition device (25) added in an amount that has a low upward flow rate the liquid within the drop distance between the addition device (25) and branch (22). This ensures that the drop distance (21) or Down pipe below the branch (22) is always filled with relatively fresh flushing oil. In this part of the drop section (21) there is a so-called stable stratification Flushing oil. If nothing is diverted via branch (22), the flushing oil rises in the falling section (21) and ultimately arrives in reactor (1).

While preferably the majority of the organic components of the depolymerizate is derived through branch (22), pass through the depolymerizate contained, predominantly inorganic solid particles, which are sufficient Have sink rate, the part of the drop section (21) filled with flushing oil. For this purpose, the organic depolymerizate constituents still adhering to the solid particles washed off or dissolved in the flushing oil.

The difference in density between the depolymerizate and the flushing oil should be at least 0.1 g / ml, preferably 0.3 to 0.4 g / ml. The depolymerizate has one Temperature of 400 ° C a density of the order of 0.5 g / ml. As a suitable one Flushing oil can e.g. B. a heated to about 100 ° C vacuum gas oil with a density of approx. 0.8 g / ml can be used.

The length of the portion of the drop section (21) filled with flushing oil is dimensioned such that the solid particles at the lower end of the drop section (21) at least largely are free from adhering organic depolymer components. It is also dependent of type, composition, temperature and the quantities enforced of the depolymerizate and the flushing oil used. Those skilled in the art can use relative simple tests the optimal length of the part of the drop section filled with flushing oil (21) determine.

As shown in Figure 3, the solid particles with part of the flushing oil discharged via lock (24). Lock (24) is used for pressure separation of the previous and the following plant section. A cellular wheel sluice is preferred used. But also other types of locks, e.g. B. cycle locks are suitable for this purpose. The discharged mixture has a solids content from about 40 to 60% by weight.

Appropriately, lock (24) is followed by a further separation device (26) for separation of flushing oil and solid particles.

A scraper conveyor or a screw conveyor is preferably used as the separating device (26) used. These are directed obliquely upwards in the conveying direction. Prefers is an angle to the horizontal of 30 to 60 °, in particular about 45 °.

FIG. 5 shows another process variant. The solid particles pass through here after passing the falling distance (21) immediately the separating device (26). About one Gas cushion, e.g. B. from nitrogen, and the addition of flushing oil is in the separator (26) a desired liquid level (34) is set. Most of flushing oil freed solid particles are then over lock (24), z. B. a cellular wheel lock or cycle lock, discharged.

A drainage screw (26) is shown schematically in FIG Separator can act. A flushing oil can also be carried out via line (30) with a lower density, e.g. B. a middle distillate oil. Hereby the heavier flushing oil is washed off the solid particles. The lower viscosity light flushing oil is easier and at least without major difficulties largely separate from the solid particles. The used flushing oil can be discharged via line (29), or at least partially into the via branch (22) derived depolymerizate can be introduced. The separator (26) works here preferably under atmospheric conditions. The so separated Solid particles are discharged via line (11) and can be recycled be fed.

If plastics from household collections are used as old and waste plastics, the solid discharged via line (11) consists predominantly of metallic Aluminum, which is then used for recycling this material can be.

FIG. 4 shows an enlarged detail of FIG. 3, the T-shaped arrangement of Fall section (21) and branch (22). Mechanical separation aids are also shown (23) and the flow conditions shown schematically with arrows.

After separation of gas and condensate, the depolymerizate is easy to handle, since it remains well pumpable above 200 ° C and is a good feed material in this form for the subsequent process stages and other uses represents.

However, the depolymerizate can also solidify by means of a so-called cooling belt and thus brought into a solid form. Are suitable for. B. endless belts made of stainless steel. They usually run under tension over cylindrical ones Deflection drums or deflection disks. The product can, for example, by means of a Broadband nozzle can be applied as a film in the front area of the cooling belt. The underside of the cooling belt is sprayed with cooling liquid, the product but is not wetted. This cooling of the strip also causes this to happen existing product lowers temperature and solidifies. In addition to the Cooling from below, the depolymerizate can be cooled by supply air from above. The solid film formed can at the end of the cooling belt z. B. by means of a routing Crushing roller or broken by a lattice crusher. For the Subsequent processing or storage has proven beneficial if the fragments are not larger than the size of the palm of your hand. If necessary. can the fragments also crushed further z. B. be ground.

The depolymerizate can be pumped directly into the subsequent process stages introduced or used for other purposes. If intermediate storage is necessary, this should be done in tanks in the the depolymerizate is kept at temperatures at which it is easy to pump remains, usually at over 200 ° C. If longer storage is desired, please do so lends itself to storing the depolymerizate in solid form. In broken form the depolymerizate can be transported in the same way as fossil fuel hard coal, stored and fed to subsequent processes and uses.

The present invention relates to methods according to claims 1, 3 and 5 and uses according to claims 7 and 8.

A depolymerizate is preferred used, which is at least largely of coarser inorganic Solid particles, especially metallic aluminum, are freed.

In the inventive method according to claim 1 is at least a partial stream of the depolymerized product is subjected to coking together with coal. Not every coal is suitable for the production of high quality coke. A such coke, for example metallurgical coke, should be as coarse as possible and less friable be. It must have a minimum strength so that it is sufficient Filling in the blast furnace can be achieved without the coke under the weight the bed disintegrates and as a result the blast furnace is clogged. Suitable coals are, for example, the baking fat coal of the Ruhr area or gas coal Such baking coals are available in limited quantities and are more expensive than, for example, boiler coal.

Surprisingly, it was found that poorly baking coals in the coking process baked together if depolymerizate is added to them. While the high-temperature coking process, which is usually in the range between 900 to approx. 1400 ° C in the absence of air arise from the introduced Depolymerizat apparently coking products with binder properties that cause the coal to bake. The same applies to the coking of Lignite for the production of Grudekoks z. B. in the hearth furnace process. The desired one The caking effect is achieved when the depolymerizate and Coal in a ratio of 1: 200 to 1:10 can be used. As particularly cheap has shown a range from 1:50 to 1:20.

In the inventive method according to claim 3, at least a partial stream of Depolymerizats subjected to thermal recycling. Under thermal recovery is the oxidation of a substrate using the resulting Understand the tone of heat. Because of its high energy content and its Compared to old or waste plastics, relatively low chlorine content at the same time With high homogeneity, the depolymerizate is a suitable fuel for use in all types of power plants and in cement plants. The depolymerizate both liquid at temperatures above 200 ° C over lances, e.g. B. as a substitute for heavy fuel oil, be injected or in solid form, e.g. B. broken or ground, introduced.

In the inventive method according to claim 5, at least one Partial stream of the depolymerized product is used as a reducing agent in a blast furnace process. The depolymerizate can also be used as a substitute for heavy fuel oils, which are usually used for this purpose. It turns out here, as in thermal recycling, the relative low chlorine of the Depolymerizate of less than 0.5 wt .-% as a special advantage.

The depolymerizate leaves It is therefore advantageous as a binding additive in the coking of coal, as a reducing agent in blast furnace processes and as fuel in combustion plants, power plants and cement plants.

Furthermore, it can Depolymerizate as an additive to bitumen and bituminous products be used. Polymer modified bitumen is used in many areas of the Construction industry, especially used in roof sealing materials and in road construction. The polymers contained in the depolymerize the properties of the Bitumen such as toughness, stretchability and abrasion ability improved. The depolymerizate works due to its residual reactivity when heated together with bitumen and bitumen derivatives chemical bonds. This is partly the cause of the mentioned and desired property improvements.

This modification can reduce the cold flexibility and the stability of the bituminous Material can be improved. An improvement in the elastic properties the bitumen and the adherence to the mineral filling material can also be achieved by admixing polymers. The chemical reaction with the bitumen also has the advantage that z. B. in hot storage none Segregation can take place or this is severely restricted. The residual reactivity the depolymerizate can be introduced by introducing functional groups, for example according to the procedures according to European patent applications EP 0 327 698, EP 0 436 803 and EP 0 537 638 can be increased. If necessary. can the so modified Bitumen or bituminous products also contain crosslinking agents (see EP 0 537 638 A1).

An addition of 1 to 20 parts by weight of depolymerizate per 100 has proven practical Parts by weight of bitumen proved. An addition of 5 to 15 parts by weight is particularly favorable Depolymerisate per 100 parts by weight of bitumen.

example 1 Depolymerization of old plastics

In a stirred tank reactor with 80 m ³ content, which is provided with a circulation system with a capacity of 150 m ³ / h, 5 t / h mixed agglomerated plastic particles with an average grain diameter of 8 mm were fed pneumatically. The mixed plastic was material that came from a household collection of the Dual System Germany (DSD) and typically contained 8% PVC.

The plastic mixture was depolymerized in the reactor at temperatures between 360 ° C and 420 ° C. Four fractions were formed, the quantity distribution depending on the reactor temperature is shown in the following table: I. II III IV T [° C] Gas [wt%] Condensate [% by weight] Depolymerizate [% by weight] HCl [% by weight] 360 4th 13 81 2nd 380 8th 27 62 3rd 400 11 39 46 4th 420 13 47 36 4th

The depolymerizate stream (III) was drawn off continuously. The viscosity of the depolymerizate was 200 mPas at 175 ° C.

Example 2

Depolymerizate from processing from waste plastics from household collections of the DSD according to Example 1 was one in different proportions Coking coal added. The mixtures were coked in a test coke oven.

Cokes with the properties described below were obtained: Trial number 1 2nd 3rd 4th relationship Coal / depolymerizate 100: 0 99: 1 98: 2 95: 5 CRI index 29 28 27 27 CSR index 59 61 62 63 Coke resistance M 40 (in%) 73 76 77 78 Meat coke M 10 (in%) 8th 7 6 5

CRI:

Coke Reaktion Index

CSR:

Coke Strength after Reaktion Index

M 40:

MICUM-Test 40

M 10:

MICUM-Test 10

The values show that the addition of depolymerizate improves the coke resistance (M 40) and reduces the tendency to wear (M 10). Furthermore, the gasification reactivity (CRI index) is reduced, accompanied by an improved coke resistance after gasification (CRI index) with the addition of a depolymerizate.

CRI:

C oke RESPONSE I ndex

CSR:

C oke S trength after RESPONSE Index

M 40:

MICUM test 40

M 10:

MICUM test 10

Claims (10)

1. Process for extracting chemical raw materials and/or liquid fuel components from used or waste plastics, in which the used or waste plastics are depolymerized at elevated temperature, optionally with the addition of a liquid auxiliary phase, a solvent or solvent mixture, and the gaseous and condensable depolymerization products (condensate) produced and also a pumpable viscous liquid phase (depolymerized material) containing depolymerization products are drawn off in separate subflows and condensate and also depolymerized material are worked up separately from one another, characterized in that at least one subflow of the depolymerized material is added to coal to be coked for the purpose of better coking during the coking process and is subjected to coking together with the coal.
2. Process according to Claim 1, characterized in that the depolymerized material and the coal are used in a ratio of 1:200 to 1:10, preferably 1:50 to 1:20.
3. Process according to the preamble of Claim 1, characterized in that at least one subflow of the depolymerized material is subjected to an oxidation utilizing the heat of reaction produced in this process.
4. Process according to Claim 3, characterized in that the depolymerized material is oxidized in power stations and cement factories.
5. Process according to the preamble of Claim 1, characterized in that at least one subflow of the depolymerized material is utilized as reducing agent in a blast-furnace process.
6. Process according to at least one of the preceding claims, characterized in that the depolymerized material is used as a pumpable material at a temperature above 200°C or as a solid preferably ground or crushed after cooling.
7. Use of a depolymerized material produced by a process in accordance with the preamble of Claim 1 as a fuel in furnaces, power stations and cement factories, as a reducing agent in blast-furnace processes and also as a binding addition in the coking of coal.
8. Use of a depolymerized material produced by a process in accordance with the preamble of Claim 1 as an additive to bitumen and bitumen-containing products.
9. Use according to Claim 8, characterized in that 1 to 20, preferably 5 to 15, parts by weight of depolymerized material are added per 100 parts by weight of bitumen.
10. Use according to one of Claims 7 to 9, characterized in that depolymerized material is used which is at least largely freed of coarser inorganic solid-state particles.

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