NL1029511C2 - Waste bituminous roof covering material recycling process, comprises heating granular waste material inside screw conveyor - Google Patents

Abstract

Granular waste material is supplied to a screw conveyor system (2) and transported through this system whilst being heated. A process for recycling waste bituminous roof covering material comprises supplying the waste as a granular material to a screw conveyor system, transporting the material through this system whilst heating in order to melt at least some of the granules and discharging the at least partly molten material from this system. INDEPENDENT CLAIMS are also included for the following: (A) Recycling apparatus for carrying out this process, comprising a transport space (4) for receiving the granular waste, at least one inlet (5) for the waste, at least one screw (3) for transporting and mixing the waste, a system (7) for heating the waste in the transport space and at least one outlet (9) for the material; (B) Recycled material produced by this process; and (C) Molded article formed by molding this recycled material.

Description

Title: Method and device for recycling bituminous roofing waste, as well as mass obtained by such a process and casting formed from such a mass.

The invention relates to a method and device for recycling bituminous roofing waste. The invention further relates to a mass obtained by such a method and a casting formed from such a mass.

From the Dutch patent publication NL1005029 a technique for recycling bitumen-containing webs is known. With this known technique, bitumen-containing webs to be recycled are poured into a melting bin, the melting bin being filled with hot bitumen above the dumped webs. A steel conveyor belt is furthermore present in the melting tray which slowly moves the dumped webs. Circulating currents are generated in the melting tank by means of pumps. The hot bitumen is hereby guided along the bitumen-containing webs at high speed and the bitumen of the bitumen-containing webs is melted. Contamination of the bitumen in the melting bin is removed with the help of filters. The conveyor belt transports the remains of the tracks from the melting bin to a waste container.

A drawback of the known technique is that it is not very efficient. For example, addition of hot bitumen is required to recover the bitumen from the bitumen-containing webs. Furthermore, pumps are needed to maintain circulating flows in the melting tank. Filters are also needed to remove contaminants.

The object of the invention is to provide a method and a device with the aid of which bituminous roofing waste can be recycled in a more efficient manner.

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To this end, according to the invention, a method according to claim 1 is provided, as well as a device according to claim 7.

Because, in the technique according to the invention, screw transport in combination with heating results in an extremely good mixing of bituminous granules melting during transport, an optimum homogeneity of the cohesive mass increasing during screw transport is obtained, without the need for the addition of hot bitumen and / or without the need for additional circulating flows of the mass. The synergistic effects of the use of granules and the combined transport, mixing and heating of the granules thus lead to a more efficient technique for recycling bituminous roofing waste.

A mass according to claim 19 and a casting according to claim 20 is also provided.

Specific embodiments of the invention are laid down in the subclaims.

In the following, the invention is further elucidated with reference to the figures in the accompanying drawing.

Figure 1 shows diagrammatically in side view a longitudinal section of an example of an embodiment of a device according to the invention.

Figure 2 shows diagrammatically in plan view a part of a longitudinal section of an example of a double-screw conveyor screw system of a device according to the invention.

Figure 3 shows a schematic perspective view of a first example of a sieve drum for use in a device according to the invention.

Figure 4 is a schematic perspective view of a second example of a sieve drum for use in a device according to the invention.

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Figure 5 shows diagrammatically in perspective an example of a mold for use in a device according to the invention.

Reference is first made to Figure 1. This figure shows a | device 1 for recycling bituminous roofing waste. Bituminous roofing waste usually consists of layers of various types of bituminous membranes with carriers of, for example, glass fleece, polyester fleece or wool felt, jute, glass fabric and the like. The bitumen can be blown (oxidized) or modified with polymers such as atactic polypropylene or styrene butadiene styrene block copolymer. Bituminous roofing waste can be obtained from rejected specimens when producing roofing rolls, or from material from roof dismantling. Prior to recycling the roof waste by means of the device 1, the roof waste may have undergone various pre-processing operations. For example, with material originating from roof dismantling, materials such as gravel, wood, and the like may already have been removed, while for example slate or other contaminants may still be present in the roof waste to a greater or lesser extent.

The device 1 comprises a conveyor screw system 2 provided with a conveyor space 4 which is adapted to receive granules of bituminous roofing waste. The conveyor screw system 2 is further provided with an inlet 5 for supplying bituminous granules to the conveyor space 4. These granules can be obtained by granulation of the bituminous roofing waste, for example by means of cold shredding techniques. But the grains can also be manufactured in other suitable ways.

The transport screw system 2 is furthermore provided with a transport screw 3 which is adapted to transport and mix said granules in the transport space 4. The transport space 4 is delimited by a jacket 6 of the transport screw system 2.

In the example shown, the casing 6 is a substantially cylindrical sleeve 30 in which the transport screw 3 is rotatably arranged. However, other jackets are possible, for example in the form of a trough. The conveyor screw system 2 can be accommodated in a housing 8 of the device 1.

In the example shown, the conveyor screw 3 has a screw shaft 31 with one helical length elongated screw blade 32. Various parameters of the conveyor screw, such as diameter of the conveyor screw, length, pitch, rotational speed, and the like, can be selected according to the desired behavior of the process to be carried out with the aid of the device. Greater pitch, for example, gives faster throughput and will therefore have less temperature rise to give. Greater length, for example, gives higher temperature rise with given heat transfer per unit of length. An example of a suitable diameter of the transport screw is approximately 70 cm.

The conveyor screw system 2 further comprises a heating system 7 which is adapted to raise the temperature of the material to be conveyed and to be mixed in the conveyor space 4 of the conveyor screw system 2, at least a part of said granules melting at least partially. The heating system 7 can, as in this example, be adapted to heat the granules by circulation of thermal oil and, for the benefit of that circulation, hollow blades 32 and / or propeller shaft 31 of the conveyor screw 3 and / or hollow walls of the jacket 6. The advantage of this is that the combined processes of transport, mixing and heating run in an extremely efficient manner.

However, other heating systems can also be used.

The conveyor screw system 2 further comprises an outlet 9 for discharging from the conveyor space 4 a mass comprising at least a part of the said granules in an at least partially molten state.

The outlet can have various shapes and dimensions and can be situated at various places in the conveyor screw system 2. In the example shown 10295 the outlet 9 is situated at the end of the conveyor screw system 2 remote from the inlet 5. In cross section, the outlet 9 is a mouth of a portion 33 of the casing 6 narrowing towards the mouth. This narrowing part 33 contributes to a build-up 5 of the mass pressure in the transport space 4. Other means for such a pressure build-up however, operations are possible, for example a resilient valve which can at least partially close the outlet.

On the basis of the shown example of the device 1, an example of a method for recycling bituminous roofing waste is now described.

Bituminous roofing granules are supplied to the transport space 4 via the input 5. Such granules can be bonded together to a greater or lesser extent. The conveyor screw system 2 can be provided with means for loosening of adhered grains. In the example shown in Figure 1, these means comprise a number of blades 10. The blades 10 are mounted on the screw axis 31 of the conveyor screw 3 at the location of a screw section 11 where the grains are supplied to the transport space 4. the screw blades 32 of the conveyor screw 3 do not extend over the screw section 11. Alternatively, the screw blades may extend over the section 11, while the blades are mounted on the blade blades. The blades 10, whether or not arranged on the propeller blades 32, may optionally be hollow for the said thermal oil circulation of the heating system 7.

By means of the transport screw system 2, the granules are transported in a manner shown in FIG. 1 conveying direction of the conveyor screw system 2, indicated by an arrow T. Thereby, the pellets are also mixed and heated by means of the conveyor screw system 1029511 6 2. An example of a suitable heating temperature is approximately 200 degrees Celsius.

As a result of heating, part of the granules melts at least partially. Depending on the viscosity of the molten part, a coherent mass increases during transport. This mass comprises at least a part of said granules in an at least partially molten state, the cohesiveness of the mass being at least determined by molten parts of the heated granules. The associated mass is discharged from the conveyor system via the outlet 9. The discharged mass can then be used for various applications.

An example of such an application is the use of the discharged mass in a seal of the bed of a waterway as described in Dutch patent applications NL1025760 and NL1025761. For example, the mass discharged from the conveyor screw system 2 can be used as a filling mass for (in situ) manufacturing (and applying) a composite membrane. Such a composite membrane can for instance be manufactured by providing a first (prefabricated) sub-membrane on a substrate on which the filling mass is poured, whereafter a second sub-membrane is optionally applied to the filling mass. Such a composite membrane can also be manufactured in situ and placed in a bed of a waterway, for example, by rolling out a first prefabricated sub-membrane on a floating platform, pouring the filling mass on the rolled-out sub-membrane, and a second prefabricated on the filling mass. sub-membrane is applied while the platform is moving and the finished composite membrane is guided at one end of the platform to the bottom to be sealed.

Another example of such an application is the manufacture of bituminous castings, such as tiles, mats and the like. To that end, the device 1 can comprise a mold 12 which, in operation, is arranged on the outlet 9, see Figs. 1. The discharged mass can be caught in the mold 12 to form the castings. The mold may optionally extend downstream of the conveyor screw system 2 over a large distance, whereby elongated webs of the mass are formed in the mold. The castings to be formed can then be obtained from such webs, for example by cutting them off the webs. The mold can further be provided with cooling means for cooling the mass in the mold.

10 Other important examples of castings are setting pieces for filling up roof details (so-called mastic shots) and edges of roof windows. An advantage of such castings in such applications is the high weight, which gives ballast and therefore wind resistance. Other important advantages include good screwability and excellent adhesion of the bituminous roofing rolls to be applied.

The device 1 can further be provided with one or more supply and / or discharge channels 14, 15, 16 and 17 which connect the transport space 4 and / or the space between the housing 8 and the transport screw 3 to the exterior of the device 1. Via such channels, for example, substances can be removed from the system and, for example, vapors released during the process can be discharged, if desired with the use of suitable extraction means. Via such channels substances / substances can also be added to the mass in the transport space, for instance for influencing the viscosity of the mass or for otherwise adjusting the properties of the mass. For example, liquid bitumen, mineral or vegetable oil, gravel, fibers, powdered agents, or other desired substances can be added.

The device 1 can further be provided at various suitable places with sieving means for sieving the mass. In the example shown 10295 1 8, the conveyor screw system 2 is provided with such screening means in the form of a screening outlet 18. By means of such a screening outlet the mass can be screened and discharged from the transportation space 4. In the embodiment shown in FIG. 1, such a screen output is formed in that the casing 6 has a section 19 which comprises a screen drum 18. This screen drum is shown in more detail in FIG. 3. The screen drum 18 has screen openings 20. In operation, a fine fraction of the mass propelled by the conveyor screw 3 is discharged from the conveyor space 4 via the screen openings 20, while a coarse fraction of the propelled mass is discharged via the outlet 9. In this way a stream of fine bitumen can be produced from roofing waste, which can be used, for example, as a (basis for) binding agent in asphalt or for making roofing rolls. From the coarse fraction of the mass obtained by means of the screen 18, castings can be formed with the aid of the mold 12.

It is noted that various means for building up the pressure of the mass in the transport space 4 can be used to promote the removal of the fine fraction through the screen openings 20. In the embodiment shown in FIG. 1, the jacket 6 narrowing in the outlet 9 contributes to such a pressure build-up. As stated, other pressure build-up provisions are also possible, for example a resilient valve which can at least partially close the outlet 9.

The separation into a coarse and a fine fraction can be influenced in various ways. For example, the shapes and dimensions of the screen openings 20 of the screen drum 18 can be varied. The heating temperature, and therefore the viscosity of the propelled mass, can also be varied. Furthermore, the residence time of the mass in the transport space 4 can be varied and diluting bitumen and / or (mineral or vegetable) oil can be added.

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Thus, with the aid of the method, a mass can always be obtained with desired properties. Examples of such properties can be: softening point "ring and ball" which is higher than 100 degrees Celsius (European standard EN1427), penetration at 25 degrees Celsius which is lower than 50 dmm (European standard EN1426); (1 mm = 0.1 mm). These properties can be varied and improved by sieving into a fraction with good flowe properties (low fiber) and a fraction with high strength and toughness due to the presence of fibers and many mineral components. The first fraction can be further optimized by adding means and thereby be made suitable for producing new roof membranes or heat-processable binders for road construction.

Experiments indicate that the mass obtained always has a certain coherence. The degree of coherence can be varied by changing temperature and additions.

In the example shown, the screen openings 20 of the screen drum 18 are elongated and extend parallel to the conveying direction T with their longitudinal direction. An advantage hereof is that the mass propelled in the transport space 4 in the transport direction T experiences less resistance from the sieve drum 18 than in other directions. This has a favorable influence on the propulsion efficiency.

It is noted that, instead of or in addition to a screen, the device 1 can also comprise one or more other separation units for separating the mass into at least a first fraction and a second fraction. For example, a separation unit can be applied at various places in the device 1 which leads a mass flow to the mold 12 and a different mass flow to a different collection unit.

Reference is now made to FIG. 2. This figure shows, in top view, a part of a longitudinal section of a double-screw conveyor screw system 52, comprising two 10295 conveyor screws 53A, 53B in a casing 56 defining a conveyor space 54. The transport screws are placed parallel to each other with their longitudinal directions. In the example shown, the turns of the one conveyor screw partially extend into the spaces between the turns of the other conveyor screw. However, other mutual arrangements of the transport screws, in which the windings of the one transport screw do not partially extend in the spaces between the windings of the other transport screw, are also possible.

An advantage of a twin-screw version is that, depending on the circumstances, a higher propulsion efficiency and / or a better mixing and / or a faster process flow can be achieved.

Such double-screw designs can have conveyor screws 53A, 53B with mutually equal or opposite directions of rotation, or with an adjustable direction of rotation of at least one conveyor screw. Different rotational speeds are also possible in certain cases.

The choice of the mutual rotation directions and (mutual) rotation speeds can, depending on the circumstances, influence, among other things, the propulsion efficiency and / or the mixing and / or the speed of the process progress. In addition to double-screw versions, embodiments with more than two transport screws are also possible, whereby different relative directions of rotation and / or rotation speeds of the screws are possible.

FIG. 4 shows an example of a screen output 68 for use in the twin-screw conveyor screw system 52 of FIG. 2. The screen output comprises a casing 56 of the conveyor screw system 52 with a section 69 comprising a double-screw screen drum 68. In the example shown, the double-screw screen drum 68 has screen openings 70 that are similar to the screen openings 20 of the single-screw screen drum 18 of FIG. 3. 1 10295 1 1 11

However, screen openings with various other shapes and dimensions are also possible.

FIG. 5 shows an example of a mold 62 for use with the twin screw conveyor screw system 52 of FIG. 2. The mold 62 can be in | 5 operation on an outlet 59 of the conveyor screw system 52. The discharged mass can be collected in the mold 62 to form castings. It is noted that the double-screw transport screw system 52 shown also comprises a pressure building provision 83 for building up the mass pressure in the transport space 54. In the example shown, this pressure building device 83 is a narrowing part of the casing 56 that defines the transport space 54.

A special application of the described method and device for recycling bituminous roofing waste is to bring bituminous granules into contact with hot bitumen such that the granules hardly melt. For example, with a device as shown in Figs. 1, are introduced into the transport space 4 via the input 5, while hot bitumen is added to the granules in the transport space 4 via one or more of the channels 14, 15. In order to achieve that the pellets hardly melt in the process, the heating system 7 can then hardly be or hardly be in operation and / or the hot bitumen can only be brought into contact with the pellets for a short time. The latter can be realized, for example, by adding the hot bitumen near the end of the conveyor screw path to be traversed.

A mass withdrawn from the conveyor screw system is thus obtained with a very good castability and manageability. The granules transformed into castable mass are therefore particularly suitable for transfer and temporary storage, for example. In later use for various applications, the pourable mass obtained can then be melted up without further additives, whereby the content of the granules will only have its full effect and the viscosity will (drastically) increase.

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Transforming the granules into a pourable mass therefore offers logistical advantages.

It is noted that the above-mentioned examples of embodiments do not limit the invention and that various alternatives are possible within the scope of the appended claims.

Various types of transport screws can thus be used. For example, on one propeller shaft instead of one propeller blade elongated in helicoidal direction, more than one propeller blade may also be provided. It is also possible for a number of shorter screw blades to be arranged on a propeller shaft, instead of elongated helical blades 10. Furthermore, transport screws with helicoidal direction elongated propeller blades can also be designed without a propeller shaft.

Other alternatives are formed, for example, by using more or less separate units for, respectively, freeing, heating and sieving. Such units do not necessarily have to be mutually aligned with the same axes, but can also function independently of one another in various other ways. This can offer benefits. For example, the unloading unit can be made relatively large and therefore also serve as a storage buffer. The heating unit may, for example, be of double or multi-screw design, while a screen unit connected thereto may be of single-screw design for cost or construction reasons.

However, other variants or modifications are also possible. These and similar alternatives are understood to fall within the scope of the invention as defined in the appended claims.

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Claims (20)

Method for recycling bituminous roofing waste, wherein: granules of bituminous roofing waste are provided; - the granules are supplied to a conveyor screw system (2; 52); - the pellets are transported and mixed together by means of the conveyor screw system (2; 52), while the pellets are heated thereby whereby at least a part of the pellets at least partially melts; and - a mass that comprises at least a part of said granules in an at least partially molten state is discharged from the conveyor screw system (2; 52). A method according to claim 1, wherein the discharged mass is at least partially received in a mold (12; 62) for forming castings. 15 Method according to claim 1 or 2, wherein the mass is separated into at least a first fraction and a second fraction. 4. Method as claimed in any of the foregoing claims, wherein the mass is sieved. 5. Method as claimed in any of the foregoing claims, wherein to the granules, while being transported by means of the conveyor screw system (2; 52), means for adjusting properties of the mass to be discharged are added. 1 0295 1 1 The method of claim 5, wherein the means for adjusting properties of the mass to be discharged comprises hot bitumen and adjusting properties of the mass to be discharged is making the mass to be discharged castable. 5 Device for recycling bituminous roofing waste, comprising a conveyor screw system (2; 52) provided with: a transport space (4; 54) adapted to receive granules of bituminous roofing waste; 10. at least one input (5) for supplying said granules to the transport space (4; 54); - at least one transport screw (3; 53A, 53B) which is adapted to transport and mix said granules in the transport space (4; 54); A heating system (7) adapted to raise the temperature of said granules in the transport space (4; 54), at least a part of said granules melting at least partially; and - at least one outlet (9, 18; 59, 68) for discharging from the transport space (4; 54.) a mass comprising at least a part of said granules in an at least partially molten state. The device of claim 7, further comprising a pressure building facility (33; 83) for building the pressure of the mass in the transport space (4; 54). 25 The device of claim 8, wherein the pressure building feature (33; 83) is a narrowing portion of a jacket (6; 56) defining the transport space (4; 54). 1 0295 1 1 Device as claimed in any of the claims 7-9, further comprising a mold (12; 62) which is adapted to at least partially receive the discharged mass and to form castings from the collected mass. 5 The device of any one of claims 7 to 10, further comprising a separation unit (18; 68) for separating the mass into at least a first fraction and a second fraction. The device according to any of claims 7 to 11, further comprising a screen (18; 68) provided with screen openings (20; 70) for sieving the mass. 13. Device as claimed in claim 12, insofar as dependent on claim 10, wherein the mold (12; 62) is adapted to form castings from a coarse fraction of the mass obtained by means of the sieve (18; 68). Device according to claim 12 or 13, wherein the screen openings (20; 70) form part of the at least one outlet. Device according to any of claims 12 to 14, wherein the screen openings (20; 70) are elongated and extend with their longitudinal direction parallel to a conveying direction (T) of the conveying screw system (2; 52). Apparatus according to any of claims 7 to 15, further comprising a loosening reel unit (10) for loosening the bituminous grains from each other. 1029511 30 The apparatus of claim 16, wherein the unloading unit comprises blades (10) mounted on the at least one conveyor screw (3; 53A, 53B). Device according to one of claims 7 to 17, wherein the heating system (7) is based on circulation of thermal oil through hollow parts (3, 6, 10; 53A, 53B, 56) of the conveyor screw system (2; 52) ). A mass comprising granules of bituminous roofing waste in an at least partially molten state obtained by a method according to any one of claims 1 to 6, or with similar properties. 20. Casting piece formed by a mold from a mass according to claim 19. 1 0295 1 1