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Title:
METHOD FOR PRODUCING AN ASPHALT PRODUCT, AN ASPHALT PRODUCT AS SUCH, AN APPARATUS FOR PRODUCING AN ASPHALT PRODUCT
Document Type and Number:
WIPO Patent Application WO/2019/134729
Kind Code:
A1
Abstract:
The invention relates to a method for producing an asphalt product. The method comprises providing a shredded asphalt-containing road construction materials being disposed from a road surface, the road construction materials being shredded into a size of maximum 50 mm3. Also, shredded bitumen-containing roofing materials being disposed from a building are provided, the roofing materials being shredded into a size of maximum 50 mm3. The materials are mixed at ambient temperature without applying heating. Thereafter, the materials are heated, in a reactor, to a temperature of between 120°C and 190°C by applying heating to the mixture along heating conductors inside the reactor. The invention also relates to an apparatus for producing the asphalt product and to an asphalt product as such.

Inventors:
RASMUSSEN, Karsten (Strandvejen 340 A, 2980 Kokkedal, 2980, DK)
Application Number:
DK2019/050006
Publication Date:
July 11, 2019
Filing Date:
January 08, 2019
Export Citation:
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Assignee:
ENVISO GROUP A/S (Naverland 2, 2600 Glostrup, 2600, DK)
International Classes:
C08L95/00; E01C19/00; B02C18/22; B09B3/00; B29B17/04
Attorney, Agent or Firm:
PATRADE A/S (Ceresbyen 75, 8000 Aarhus C, 8000, DK)
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Claims:
CLAIMS

1. Method for producing an asphalt product, the method comprising the following steps:

- providing asphalt-containing road construction materials being retrieved from a road surface and shredding the road construction materials into a size of maximum 50 mm3

- providing bitumen-containing roofing materials, possibly being retrieved from a building, and shredding the roofing materials into a size of maximum 50 mm2

- mixing the asphalt-containing road construction materials and the bitumen- containing roofing materials, at ambient temperature without applying heat,

- heating, in a reactor, the mixture to a temperature of between l20°C and l90°C by applying heating to the mixture along heating conductors inside or integrated into the vessel. 2. Method according to claim 1 for producing an asphalt product, the method compris- ing the further steps of:

- providing at least one additive selected from the following additives: Rejuvenator, flux oil and hard wax,

- mixing, the at least one additive into the mixture of shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials, at am bient temperature without applying heating.

3. Method according to claim 1 or 2 for producing an asphalt product, where

- a weight ratio between the shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials is between 100: 1 and 100:5, and

- a weight ratio between the mixture of shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials and the additive, is between 100: 1 and 100: 10.

4. Asphalt product comprising shredded asphalt-containing road construction materi als and shredded bitumen-containing roofing materials, said asphalt product not con taining virgin bitumen, and said asphalt product only containing bitumen obtained from the bitumen-containing roofing and retrieved road-building materials.

5. Asphalt product according to claim 3, where a weight ratio between the shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials is between 100: 1 and 100:5.

6. Asphalt product according to claim 4 or 5, the asphalt product also containing at least one additive selected from the following additives: rejuvenator, flux oil and hard wax. 7. Asphalt product according to any of claims 4-6, where a weight ratio between the mixture of shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials and the additive is between 0.1% and 0.5%.

8. Apparatus for mixing shredded asphalt-containing road construction materials being retrieved from a road surface and the shredded bitumen-containing roofing materials, possibly being retrieved from a building, the apparatus comprising

- a mixing plant for mixing the materials, the mixing plant comprising

- at least one first container (23) for storing the shredded asphalt-containing road con struction materials retrieved from a road surface and

- at least one second container (24) for storing the shredded bitumen-containing roof ing materials, possibly retrieved from a building, and

- possible at least one third container (28) for storing at least one additive, and where

- a first conveyer is provided for conveying the shredded asphalt-containing road con struction materials from the at least one first container (23) to a reactor (1), and the first conveyor (27) provided also for conveying the shredded bitumen-containing roof ing materials from the at least one second container (24) to the reactor (1), and

- where the shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials, and possibly at least one additive, is intended for being conveyed at ambient temperature along the first conveyor and forming a mixture when being conveyed by the first conveyor to the rector (1), and

- the reactor (1) having an inlet for the mixture of shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials and an inlet for possible additives and intended for heating the mixture for providing a me chanical bonding between the materials and possible additives.

9. Apparatus according to claim 9, where the reactor of the second unit has a screw conveyor provided inside the reactor for displacing the mixture of shredded asphalt- containing road construction materials and shredded bitumen-containing roofing mate- rials from the inlet of the reactor to an outlet of the reactor, said screw conveyor hav- ing a central axle and having blades extending outwards from the central axle, and where at least one of the central axle and the blades are provided with one or more cavities provided as heat conductors, and where a heated medium, preferably heated oil, is capable of being passed through the one or more cavities for conducting heat to the mixture of shredded asphalt-containing road construction materials and shredded bitumen-containing roofing materials, when the mixture is displaced by the screw conveyor from the inlet of the reactor to the outlet of the reactor.

10. Apparatus according to claim 8 or 9, where the first unit is placed on one mobile vehicle, such as a semitrailer of one truck, and the second unit is placed on another mobile vehicle such as a semitrailer of another truck, both the one and the other mo bile unit capable of being transported from one site for laying out asphalt product to another site for laying out asphalt product, and where the apparatus comprises a con veyer for conveying the mixture of shredded asphalt-containing road construction ma- terials and the shredded bitumen-containing roofing materials from the first unit placed on the one mobile to an inlet of a reactor placed on the other mobile unit.

Description:
METHOD FOR PRODUCING AN ASPHALT PRODUCT, AN ASPHALT PRODUCT AS SUCH, AN APPARATUS FOR PRODUCING AN ASPHALT PRODUCT

Field of the Invention

The invention relates to a method for producing an asphalt product. The invention also relates to an asphalt product, preferably produced by the method. The invention fur thermore relates to an apparatus for producing the asphalt product by the method.

Background of the Invention

Roofing materials containing bitumen, such as roofing membranes, generally consist of 10 to 15 weight percentage carrier material such as fiber materials and approxi- mately 70 to 80 weight percentage bitumen and other materials as well. The bitumen content used in bitumen-containing roofing materials is generally higher than the bi tumen content normally used as a binder in the production of an asphalt product for road surfaces.

In the production of bitumen-containing roofing materials such as roofing membranes, as well as products made therefrom, measures are often demanded for disposing of the roofing materials as waste. Disposing of house building materials such as roofing membranes and other structures made of, or comprising, bitumen is often costly and environmentally harmful.

In the production of asphalt for road surfaces, which also contains bitumen, a granu late is heated to a relatively high temperature, for example in the order of l80-l95°C and kept ready for mixing with virgin bitumen at the relatively high temperature in a so-called mixer. Heating the asphalt product to relatively high temperatures is costly and environmentally harmful. The heating in traditional asphalt mixers uses fossil fuels, with all the associated C0 2 related problems as well as“normal” air pollution. In a traditional asphalt mixer, the raw material is introduced into a rotation mixer ov- en. In the oven, a burner is arranged typically burning oil or gas such that the tempera- ture inside the asphalt mixing oven is relatively high or at least high enough in order to liquidize the bitumen in the raw materials. During the heating in the mixer, a num- her of undesirable side effects occur. During heating, the burning of fossil fuels as used in order to generate the necessary temperature inside the asphalt mixer creates harmful environmental emissions such as for example pollution by C02. Furthermore, as the raw material inside the mixer is heated and unavoidably come into contact with the flame of the asphalt mixer, parts of the raw material is heated to very high temper- atures at which temperatures the raw materials create harmful emissions which will be introduced into the immediate ambient environment. Also the bitumen material in contact with the flame will either be ignited and/or will form ashes, which does not provide advantageous properties to the finished asphalt.

It is known in the art to reuse bitumen containing road building materials but until now it has only been possible to make usable asphalt having a content of 30-60% re- used materials. This naturally calls for a substantial amount of new fresh/virgin mate- rial with all the environmental and cost draw backs this implies.

Object of the Invention

The object of the invention is to provide a method for producing an asphalt product, and an asphalt product as such, where the amount of fresh/virgin materials used for producing the asphalt product is negligible, and as such the method and the asphalt product is based on reusable materials, thereby limiting the environmental impact in producing the asphalt product.

Description of the Invention

The problem to be solved by the invention is solved by a method for producing an asphalt product, the method comprising the following steps:

- providing asphalt-containing road construction materials being retrieved from a road surface and shredding the road construction materials into a size of maximum 50 mm 3 - providing bitumen-containing roofing materials, possibly being retrieved from a building, and shredding the roofing materials into a size of maximum 50 mm 2

- mixing the asphalt-containing road construction materials and the bitumen- containing roofing materials in a vessel, at ambient temperature (cold-mixing), - heating, in the vessel, the mixture to a temperature of between l20°C and l90°C by applying heating to the mixture along heating conductors inside or integrated into the vessel.

The inventive method involves many inventive principles, first of all the mixture which is obtained by the method may be used as an underlay asphalt layer, i.e. the asphalt layer immediately under the finished road surface asphalt layer, and hitherto it has not been possible to make this layer entirely from reused materials. Therefore, combining asphalt product containing road construction materials, for example mate rials having been grinded away from an existing road surface and combining these with reused bitumen containing roofing materials is a very economic and environmen tally healthy method. The materials which are used in the inventive method in order to produce a new asphalt product has before been considered waste products where par ticularly the bitumen containing roofing materials have required special considerations when being disposed of or being stored. Bitumen containing materials contain sol- vents and other volatile substances which when stored in land fills may seep into the ground water and create pollution of drinking water or may evaporate into the air and thereby create air pollution. By reusing these materials in an asphalt product as ob tained with the present invention, the otherwise waste products are reused as a valua ble resource and built into roads and at the same time new resources are saved for oth- er purposes.

Furthermore, by not having the actual burning i.e. flame inside the asphalt mixer but heating means inside or integrated into the vessel in the shape of heating conductors inside the vessel, no emissions are created. Only moisture from the bitumen material fractions i.e. the asphalt product containing road construction materials and the bitu men containing roofing materials will be evacuated from the asphalt mixer. This is a very environmentally safe process. According to a preferred aspect of the method according to the invention, the method comprises the further steps of:

- providing at least one additive selected from the flowing additives: Rejuvenator, flux oil and hard wax,

- mixing, at ambient temperature without providing externally applied heating, the at least one additive into the mixture of shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials.

Particularly the cold mixing feature is advantageous, as it is only necessary to apply heat immediately before placing the asphalt. In the art it is necessary to apply heat while mixing the asphalt at the factory, and keep the mixed asphalt warm/hot while transporting it and placing it.

According to a preferred aspect of the method according to the invention,

- a weight ratio between the shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials is between 100: 1 and 100:5 , and

- a weight ratio between the mixture of shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials and the additive, is between 0% and 0,5%

As is evident from the mixing relationship between the reused materials (both roadbuilding and roofing materials) an extremely high percentage of re-use is achieved. At the same time by mixing the cold reusable materials as discussed above a high quality product is achieved.

The additive which may be added in such an insignificant amount that the overall pic ture clearly demonstrates that the resulting asphalt is very close to being completely manufactured from reusable materials, which should otherwise have been disposed of as waste.

The additive will typically be a softener, added in order to achieve a better mixing of the regenerated materials, and thereby obtain a more homogeneous mix having in creased workability, especially while being place in-situ. The problem of the invention is solved by providing an asphalt product comprising shredded asphalt-containing road construction materials and shredded bitumen- containing roofing materials, and the asphalt product not containing virgin bitumen and only containing bitumen retrieved from bitumen-containing roofing materials.

Preferably, the asphalt product is produced by the method according to the invention.

According to a preferred embodiment of the asphalt product according to the inven- tion, a weight ratio between the shredded asphalt-containing road construction materi als and the shredded bitumen-containing roofing materials is between 100: 1 and 100:5.

In a possible embodiment of the asphalt product according to the invention, the as- phalt product also containing at least one additive selected from the following addi tives:

The additive is typically a softener in a very limited amount with respect to the entire batch of asphalt product manufactured according to the present invention. For exam- ple for approximately one ton of combined retrieved asphalt product containing road construction material and bitumen containing roofing materials, approximately six kilos as softener is used. The softener mainly acts in order to create a homogenous matrix when mixing the two fractions (the asphalt product containing road construc tion materials and the bitumen containing roofing materials).

In a further possible embodiment of the asphalt product according to the invention, a weight ratio between the mixture of shredded asphalt-containing road construction materials and the shredded bitumen-containing roofing materials and the additive is between 100: 1 and 100: 10.

The object of the invention may also be obtained by an apparatus for mixing shredded asphalt-containing road construction materials being retrieved from a road surface and shredded bitumen-containing roofing materials being, the apparatus comprising - a mixing plant for mixing the materials, the mixing plant comprising - at least one first container for storing the shredded asphalt-containing road construc- tion materials and

- at least one second container for storing the shredded bitumen-containing roofing materials, and

- possible at least one third container for storing at least one additive,

- Means for conveying materials and optionally additive to a mixer, where, when the materials in the mixer are mixed to a mixture, the mixture is trans- ferred to a reactor.

In a preferred embodiment of the apparatus according to the invention, the reactor has a screw conveyor provided inside the reactor for displacing the mixture from the inlet of the reactor to the outlet of the reactor, said screw conveyor having a central axle and having blades extending outwards form the central axle, and where at least one of the central axle and the blades are provided with one or more cavities, and where a heated medium is capable of being circulated through the one or more cavities for heating the mixture when the mixture is being displaced from the inlet of the reactor to the outlet of the reactor.

The screw conveyor being provided with cavities such that a heating media for exam ple superheated steam or a special oil being circulated inside said screw conveyor provides an improved heat distribution in the material inside the reactor such that a faster and more homogenous heating is obtained in the reactor. The screw conveyor comes into contact with substantially all the material fed into the reactor and as such very good heat exchange properties between the heating media and the mixture inside the reactor is obtained. As furthermore, no direct flame is inside the reactor, no burned residue or other deteriorated asphalt product is present inside the reactor. Consequent ly, the apparatus according to the invention provides a faster more homogenous safer and environmentally friendly mixing and heating process leading to an asphalt product having very good characteristics.

In a possible embodiment of the apparatus according to the invention, the apparatus is divided into first and second units, wherein the first unit is placed on one mobile unit and the second unit is placed on another mobile unit, both the one and the other mo bile unit capable of being transported from one site for laying out the asphalt product to another site for laying out the asphalt product, and where the apparatus comprises a conveyer for conveying the mixture of shredded asphalt -containing road construction materials and the shredded bitumen-containing roofing materials from an outlet of the first unit placed on the one mobile to an inlet of the reactor placed on the second unit on the other mobile unit.

An, asphalt product- and bitumen-containing road construction materials can be pro duced, at least in part, from waste materials, namely from bitumen-containing roofing materials such as shredded roofing materials resulting from faulty production or dis- mantling of a building. Typically in the art 30-60% reused materials of these types are used in asphalt products. Since the disposal of such waste materials is otherwise cost ly, the road building company may shift at least part of the costs to the supplier of the house waste materials. By using the redundant or discarded roofing materials being retrievable form a building the asphalt product for a road surface is cheaper to produce than when using virgin bitumen. Also, the environmental impact is reduced, both in relation to consumption of materials and in relation to energy consumption.

The bitumen-containing roofing materials are mixed with the retrieved road construc tion materials in granular form with all the original components of the bitumen- containing roofing materials. The term "original" refers to components which belong to brand new roofing materials. In the case of possibly unused roofing membranes, the complete reuse of all components does not cause any problems. However, bituminous roofing membranes or the like obtained from dismantling of buildings can almost al ways be shredded without sorting out any parts and can be provided to the respective unit for mixing with the road constructing materials. However, nails and other iron parts contained in bitumen-containing roofing materials are preferably separated by means of a magnetic separator which can be assigned to the respective shredder.

A particularly useful process for reworking/reusing of roofing materials, providing suitable materials for the method discussed above, is disclosed in the applicant’s prior patent EP 1 951 450 Bl which is hereby incorporated by reference. In the simplest case, in the embodiment of the invention, the supplied bituminous roofing materials can only be introduced into an asphalt product mixer in shredded form. This applies both to roofing materials coming from dismantling and to entire webs, in particular also in the rolled-up state. The roofing construction materials are shredded to form a granulate with a piece size corresponding to the requirements of the road building material to be produced. The granulate size is selected in such a way that processing in the reactor results in the various materials integrating into an asphalt mix. Granulate size with dimensions of between 10 mm 3 and 1000 mm 3 or smaller, if preferred.

Description of the Drawing

Fig. 1A-1C are sketches of a fixed installation of an apparatus for producing an as- phalt product by a selected method of production, both according to the invention, and Fig. 2A-2B are sketches of a mobile apparatus for producing an asphalt product.

Detailed Description of the Invention

Fig. 1 shows various components of an apparatus for producing an asphalt product. The components are a reactor 1, a screw conveyer 2 with and central axle and blades (not shown) arranged inside the reactor, an electrical motor 3 with a gearbox 4 for driving the screw compressor 2, an oil heating vessel 5 for heating oil. The oil is in tended for applying heating a mixture of asphalt-containing road construction materi als and bitumen-containing roofing materials conveyed through the reactor 1. The apparatus also comprises electrical resistors 6 arranged inside the oil heating vessel 5 and for heating the oil, an oil collecting vessel 7 for collecting oil when emptying the oil heating vessel, an oil pump 8 for pumping oil from the oil collecting vessel to the oil heating vessel, when production of asphalt product is to be started, an oil pump 9 for pumping oil from the oil heating vessel 5 to the reactor 1, when the mixture of asphalt-containing road construction materials and bitumen-containing roofing mate rials is to be heated in the reactor 1.

The apparatus also comprises a feeder 10 for feeding the mixture of asphalt-containing road construction materials and bitumen-containing roofing materials to the reactor 1, hot air inlets 11 for blowing hot air into the reactor 1 at an inlet 12 of the reactor 1, and an asphalt product discharge pipe 13 constituting an outlet 14 of the reactor 1. The unit also comprises a hot air outlet 15 for letting out hot air from the reactor 1. The hot air is passed along pipes (not shown) from a hot air outlet 15 to the hot air inlets 11. Thereby, the hot air is used to preheat the mixture of shredded asphalt-containing road construction materials and shredded bitumen-containing roofing materials and the additives just when entering the reactor 1. Sidewalls 16 of the reactor 1 are provided with cavities 17 for accommodating heated oil for heating the mixture, when being conveyed through the reactor 1.

According to a preferred embodiment, the screw conveyor 2 inside the reactor 1 has cavities for the heated oil. Either the axle or the blades or both the axle and the blades are provided with cavities for accommodating heated oil. The axle and the blades of the screw conveyor 2 inside the reactor is in constantly in direct contact with the mix ture of asphalt-containing road construction materials and bitumen-containing roofing materials, when the mixture is conveyed through the rector 1. Therefore, a very effi cient heat transfer is obtained when heating is provided via the screw compressor in addition to, or instead of, heating via the sidewalls of the reactor

A frame 18 is provided for supporting the various components of the apparatus.

Fig. 2A-2B show a plant for producing an asphalt product. The plant is arranged on two semitrailers 21, 22. On the one semitrailer 21, a first unit of the plant is posi tioned. On the other semitrailer 22, a second unit of the plant is positioned.

The first unit is a unit for mixing asphalt-containing road construction materials and bitumen-containing roofing materials. The first unit comprises one container 23 for feeding already shredded asphalt-containing road construction materials being dis posed from a road surface and another container 24 for feeding already shredded bi tumen-containing roofing materials being disposed from a building. The first unit also comprises an apparatus for producing an asphalt product. The apparatus for producing an asphalt product is similar to the apparatus shown in Fig. 1 A-1C. The one semitrail er 21 also supports and oil heating vessel 5 and an oil collecting vessel 7 similar to the oil heating vessel and the oil collecting vessel described and disclosed with reference to Fig. 1A-1C.

Furthermore, the one semitrailer 21 supports a gas burner 25 for heating the oil in the oil heating vessel. Because a mobile unit may have difficulties in gaining access to electrical power for electrical conductors (see Fig. 1B) for heating the oil, a gas burner 25 with a storage tank 26 of gas is preferred, rather than electrical conductors, for heating the oil.

A conveyer 27 is provided for conveying a mixture of shredded asphalt-containing road construction materials and shredded bitumen-containing roofing materials to fur ther mixing and applied heating in a reactor provided on the other semitrailer 22.

The other semitrailer 22 supports a reactor 5 for applying heating the mixture of as phalt-containing road construction materials and bitumen-containing roofing materi als. The other semitrailer 22 also supports a tank 28 for feeding an additive. Examples of an additive to add to the mixture of shredded asphalt-containing road construction materials and shredded bitumen-containing roofing materials may be one or more of the following additives: rejuvenator, flux oil and hard wax.

The conveyor 27 conveying mixture of asphalt-containing road construction materials and bitumen-containing roofing materials from the one semitrailer 21 to the other semitrailer 22 discharges the mixture into an inlet 29 of another conveyer 30. The ad ditives are added to the mixture at the inlet 29 of the other conveyor 30.

The mixture, together with the one or more additives, is conveyed by the conveyer 30 to the inlet 12 of the reactor 1. In the reactor 1, the mixture of shredded asphalt- containing road construction materials and shredded bitumen-containing roofing mate rials and the additives are mixed together and are heated. Heating of the mixture of shredded asphalt-containing road construction materials and shredded bitumen- containing roofing materials and the additives is performed by the heating oil being heated by the oil heating vessel 5 arranged on the one semitrailer 21. The heated oil is passed from the oil heating vessel 5 on the one semitrailer to the re- actor 1 on the other semitrailer 22. The reactor 1 also has a hot air outlet 15 for letting out hot air from the reactor 1. As disclosed also in Fig. 1A-1C, the hot air is passed along pipes (not shown) from the hot air outlet 15 to hot air inlets (not shown). In this manner the hot air is used to preheat the mixture of shredded asphalt-containing road construction materials and shredded bitumen-containing roofing materials and the additives.

The now heated mixture of shredded asphalt-containing road construction materials and shredded bitumen-containing roofing materials and the additives is discharged through an asphalt discharge pipe (see Fig. 1A) at the outlet 14 of the reactor 1.

A further conveyor 31 conveys the heated mixture of shredded asphalt-containing road construction materials and shredded bitumen-containing roofing materials and the additives to a loading container 32 on a lorry 33. Now, the heated mixture of shredded asphalt-containing road construction materials and shredded bitumen- containing roofing materials and the additives is ready to be used for constructing a new road surface. The new road surface will be made of only reused bitumen- containing and asphalt-containing materials, apart from the additives which normally will be virgin additives.

The apparatus for producing an asphalt product as shown in Fig. 2A-2B is similar to the apparatus shown in Fig. 1 A-1C. Accordingly, reference is made to Fig. 1A-1C for disclosing at least some of the various components of the apparatus for producing the asphalt product, and the various components of the apparatus disclosed in Fig. 1 A-1C is therefore incorporated by reference into the disclosure of Fig. 2A-2B. However, in the apparatus shown in Fig. 2A-2B, alternative to, and preferably instead of, heating the oil by use of electric resistors, a gas burner is provided.