Apparatus for processing concrete waste

Abstract

The invention relates to an apparatus for processing stony material, in particular concrete or asphalt. The apparatus comprises a drum and a rotor that is present in the drum, wherein the rotor is configured to rotate in a rotation direction that is opposite to the rotation direction of the drum. The apparatus is arranged to rotate the drum at a rotational speed at which particles of stony material present in the drum interior space i) are carried upwards by the rotating drum; ii) subsequently get loose from the drum when they have reached a certain height; and iii) subsequently fall down in the drum; and wherein the rotor is positioned in the drum in such way that, during rotation of the drum and rotation of the rotor, the falling particles of stony material land in a particle collision zone of the rotating rotor so that they collide with a rotor blade, thereby causing that the particles are swept away from the rotating rotor and that the particles fragmentize. In this way, the apparatus can crush stony material and at the same time effectively separate generated dust from generated larger particles of stony material. This avoids the need to perform such separation as a separate post-processing step. The apparatus in particular allows to recycle concrete and obtain cement and aggregates separated from one another in one processing step.

Description

[0001] APPARATUS FOR PROCESSING CONCRETE WASTE

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a method and apparatus for processing stony material, in particular concrete.

[0004] BACKGROUND

[0005] In industrial sectors such as mining, infrastructure and construction, it is common practice that lumps of rock, minerals, concrete or other stony material are broken down into smaller fragments. In some of these fragmentation processes, particles of different sizes and / or composition are generated and concurrently separated. Each of the resulting fractions (e.g. pebbles, gravel, sand, dust) may find application for a different purpose.

[0006] In construction work, the crushing and breaking of end-of-life concrete has become more important in recent years, because there is an increased need to recycle the concrete from demolished concrete constructions. This is in particular fueled by the ever increasing conviction that conventional concrete production from natural resources should be diminished for environmental reasons (e.g. because of the emission of carbon dioxide), by the increasing scarcity of these same natural resources and by the understanding that waste concrete obtained from the demolition of buildings can at present not as easily be dumped or landfilled as in the past.

[0007] Conventional equipment for the fragmentation of stony materials exhibits however problems with the separate recovery of sand and stones on the one hand and dust on the other hand, all of which are usually formed during fragmentation. For the crushing and recycling of concrete, the corresponding problem is then that the dusty cement binder is difficult to separate from the heavier aggregates ( / .e. fillers such as sand, natural gravel, pebbles, stones). It is therefore a drawback of conventional concrete recycling methods and equipment that they are poor in recovering cement from concrete. Also, when the recycled aggregates and cement are obtained together in one recycled fraction, then this recyclate mixture is usually less suitable for the production of concrete. Neither is it attractive to isolate both components from the mixture with a separate post-processing step. Moreover, during handling of such recyclate mixture, the dusty cement easily leaches from the mixture by becoming airborne, after which it spreads through the environment. This is undesired for environmental reasons and for the reason that the cement becomes permanently unavailable for further processing.

[0008] SUMMARY OF THE INVENTION

[0009] It is therefore an object of the present invention to provide an improved apparatus and method for the fragmentation of stony material, in particular concrete or asphalt. It is an object that dust generated thereby is effectively separated from the larger particles. As regards the fragmentation of concrete, it is in particular an object that cement is effectively separated from aggregates. As regards the fragmentation of asphalt, it is in particular an object that bitumen and stones come loose from one another.

[0010] It has now been found that one or more of these objects can be reached by applying a particular apparatus. Accordingly, the present invention relates to an apparatus (1 ) for processing stony material, in particular concrete, the apparatus comprising

[0011] - a drum (2) defining a drum interior space and an exterior environment outside the drum (2), wherein the drum (2) comprises a drum rotational axis and a circumferential drum wall (3) between two terminal drum walls (4a, 4b), which circumferential drum wall (3) is rotatably driven around the drum rotational axis in a first rotational direction (5a);

[0012] - a rotor (6) that is present in the drum interior space, the rotor (6) having a rotor rotational axis and a plurality of rotor blades (6a) that define a particle collision zone (7) with respect to the rotor (6), which is a volume in which falling particles of stony material can be hit by the rotor blades (6a) during operation of the apparatus (1 ); wherein the rotor (6) is rotatably driven around the rotor rotational axis in a second rotational direction (5b) that is opposite to the first rotational direction (5a);

[0013] - a stony material inlet (8), allowing for an introduction of the stony material into the drum (2); - a stony material outlet (9), allowing for a discharge of processed stony material (17) out of the drum (2);

[0014] - an air inlet (10), allowing for an inlet of air from the exterior environment into the drum interior space when there is an underpressure in the drum (2) at the air inlet (10), wherein the air inlet (10) comprises an air inlet tube (10a) which o is present in the drum interior space where it is substantially aligned with the rotor rotational axis; o has one or more openings (11 ) in a longitudinal direction of the air inlet tube (10a); o is positioned relative to the circumferential drum wall (3) and the rotor (6) in such a way that when air enters the drum interior space via the air inlet (10), the air travels as an airflow from the one or more openings (11 ) towards the particle collision zone (7);

[0015] - an air outlet (12) which is arranged to exhaust air comprising dust (16) from the drum interior space into the exterior environment; wherein the apparatus (1 ) is arranged to rotate the circumferential drum wall (3) at a rotational speed at which particles of stony material present in the drum interior space i) are carried upwards by the rotating circumferential drum wall (3); ii) subsequently get loose from the rotating circumferential drum wall (3) when they have reached a certain height; and iii) subsequently fall down in the drum interior space; and wherein the rotor (6) is positioned in the drum (2) in such way that, during rotation of the circumferential drum wall (3) and rotation of the rotor (6), the falling particles of stony material land in the particle collision zone (7) of the rotating rotor (6) so that they collide with a rotor blade (6a), thereby causing that the particles are swept away from the rotating rotor (6) and that the particles fragmentize.

[0016] The invention further relates to a method for processing stony material, in particular concrete, comprising

[0017] - providing an apparatus (1 ) as described hereabove;

[0018] - charging the drum (2) with the stony material via the stony material inlet (8); - causing the drum (2) and the rotor (6) to rotate in opposite directions (5a, 5b), to thereby fragmentize the stony material to form a dust (16) that is airborne and a processed stony material (17) that is capable of becoming collected at the stony material outlet (9);

[0019] - allowing air to become drawn into the drum interior space via the air inlet (10) and to become exhausted from the drum interior space via the air outlet (12), wherein the exhausted air comprises the dust (16);

[0020] - collecting the processed stony material (17) from the drum (2) via the stony material outlet (9);

[0021] - collecting the dust (16) from the exhausted air.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 schematically displays a perspective view of an apparatus (1 ) according to the invention.

[0024] Figure 2 schematically displays a cross-sectional view of a first apparatus (1 ) according to the invention.

[0025] Figure 3 schematically displays a cross-sectional view of a second apparatus (1 ) according to the invention.

[0026] DETAILED DESCRIPTION OF THE INVENTION

[0027] Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various exemplary embodiments of the present invention. In particular, the relative dimensions of particles in the drum interior space, of the drum interior space itself, and of the rotor cannot be derived from the figures. The same accounts for the positions of the different components of the apparatus of the invention relative to one another, and for the positions of the particles in the drum interior space. Furthermore, the terms “first”, “second”, and the like herein, if any, are generally used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order.

[0028] In the context of the invention, by the term ‘air’ is meant gas from the Earth’s atmosphere (ambient air). Air is also meant to include gas mixtures with a composition that deviates from that of ambient air, for example by intentionally or unintentionally modifying an ambient atmosphere. It may for example be enriched or depleted with particular components, so that it for example has a higher or lower oxygen concentration, a higher or lower nitrogen concentration, a higher or lower carbon dioxide concentration, a higher or lower humidity or a higher or lower concentration of particular pollutants.

[0029] In the context of the invention, by the term ‘dust’ is meant a collection of solid particles ranging in size from e.g. 0.2-200 pm, which may be or become airborne, depending on their origin, physical characteristics and ambient conditions. Dust particles may also range in size from 0.5-100 pm or 1-50 pm.

[0030] An apparatus of the invention is suitable for the processing of stony material, in particular concrete. By this processing is meant the fragmentation of stony material that is fed to the apparatus and the concurrent separation of the thereby generated dust from the larger particles that are also generated. When (end-of-life) concrete is processed, then the process essentially concerns the liberation of the larger particles (sand, aggregate) from the dusty cement that acts as a binder in concrete, wherein both components are separated from one another.

[0031] The stony material may in principle be any material that is capable of being broken and fragmented by a physical impact. It is in principle mainly composed of inorganic materials; organic additives may be present therein in minor amounts. The stony material may comprise actual stones in a matrix of another material, which is usually the case with cement and concrete. It is usually selected from the group of concrete materials, concrete waste materials, rocks, minerals, granite, asphalt, stones, cement clinkers and bricks. In a process of the invention, the stony material is usually added as particles having a diameter that is typically smaller than 5 cm. For example, more than 95 wt.% of the stony material comprises particles that have a diameter of up to 10 cm or up to 8.5 cm, in particular a diameter in a range of 0.5-5 cm. In particular, more than 98 wt.% of the stony material comprises particles that have a diameter of up to 10 cm, in particular a diameter in a range of 0.5-5 cm. More in particular, more than 95 wt.% of the stony material comprises particles that have a diameter in a range of -4 cm. An apparatus of the invention comprises a drum to which the stony material is continuously fed when the apparatus is in operation. The drum comprises a circumferential drum wall that is closed on either side by a terminal drum wall. In this way, a drum interior space is defined inside the drum and an exterior environment is defined outside of the drum. A drum rotational axis is defined for the drum, which is an axis that extends between both terminal drum walls and around which the drum may revolve. Typically, the drum rotational axis is at a center of gravity of a cross-section of the drum (such cross-section being perpendicular to the drum rotational axis). The drum rotational axis has a particular orientation relative to its environment on Earth to allow a proper functioning of the apparatus of the invention. This orientation is usually horizontal or slightly tilted with respect to the horizontal direction. For the purpose of the present invention, by a horizontal direction is meant a direction that is perpendicular to the direction of the Earth’s gravity. In case of a tilt, the drum rotational axis is tilted by an angle of e.g. up to 2°, up to 5°, up to 10°, up to 15°, up to 20°, up to 25° or up to 30° relative to the horizontal direction. Usually, the angle is in a range of 3-27° or in a range of 8-16° relative to the horizontal direction. A tilt inherently positions one end of the circumferential drum wall lower than its other end. A tilt is usually implemented together with positioning the stony material outlet of the apparatus at the lower end of the circumferential drum wall and the stony material inlet at the higher end of the circumferential drum wall. The effect of a tilt is then that, during operation, tumbling stony material in the drum reaches the lower outlet after a certain period of time, which generally puts a limit on the residence time of the stony material inside the drum.

[0032] A different measure which also positions one end of the circumferential drum wall lower than its other end is the use of a circumferential drum wall having a conical shape. The drum rotational axis may then still be horizontal.

[0033] A cross-section of the drum perpendicular to the drum rotational axis is usually of a circular shape, so that the circumferential drum wall is a cylindrical wall. This is visualized in Figure 1 , which schematically displays a perspective view of an apparatus (1 ) of the invention having a drum (2) with a circumferential drum wall (3) that is of a cylindrical shape. The cross-section may alternatively also be of a polygon shape or yet another shape. Preferably, an inner surface of the circumferential drum wall facing the drum interior space comprises edges or other shapes that reduce the premature downwards sliding of stony material along the circumferential drum wall and so facilitate the upward movement of the stony material during rotation of the circumferential drum wall. For example, the circumferential drum wall has a corrugated surface facing the drum interior space, typically with corrugations that have an elongate dimension that is aligned with the drum rotational axis. A polygon shape of the circumferential drum wall may also have such effect.

[0034] The circumferential drum wall is rotatably driven around the drum rotational axis, which means that it is arranged to rotate around the drum rotational axis and that there are means to drive such rotation, such as an electromotor. The circumferential drum wall is further arranged to rotate in a particular direction, which is termed the first rotational direction.

[0035] Usually, an apparatus of the invention is designed such that one or both terminal drum walls are stationary during operation of the apparatus and that the circumferential drum wall rotates relative to the one or both stationary terminal drum walls. The different inlets and outlets for air and stony material are then preferably provided at a stationary terminal drum wall in the sense that inlet and outlet of air and inlet and outlet of stony material occurs through one or both stationary terminal drum walls. This is visualized in Figure 1 , which displays a circumferential drum wall rotating in a first rotational direction (5a), with the two terminal drum walls (4a, 4b) being stationary. The different inlets and outlets in the two walls are also shown; a stony material inlet (8), an air inlet (10), a stony material outlet (9) and an air outlet (12).

[0036] In an embodiment, the apparatus may comprise a stationary housing in which the circumferential drum wall is present and which is arranged to drive the circumferential drum wall (a principle according to which e.g. also a household tumble dryer is built).

[0037] An apparatus of the invention comprises a rotor comprising a plurality of rotor blades, which rotor is present in the drum interior space. A rotor rotational axis is defined for the rotor, which is an axis around which the rotor may revolve during operation of the apparatus. Usually, the rotor rotational axis is substantially parallel to the drum rotational axis. The rotor blades together reach a certain area upon rotation of the rotor around the rotor rotational axis. The total area that is reached by the rotor blades can be defined as a rotor sweep volume (a volume that is present in the drum interior space). At least a part of the rotor sweep volume forms the particle collision zone, which is that part of the rotor sweep volume where falling particles during operation of the apparatus can be hit by the rotor blades.

[0038] The rotor is rotatably driven around the rotor rotational axis, which means that it is arranged to rotate around the rotor rotational axis and that there are means to drive such rotation, such as an electromotor. The rotor is further arranged to rotate in a particular direction, which is termed the second rotational direction. Usually, the second rotational direction is opposite to the first rotational direction, which means that the circumferential drum wall rotates opposite to the rotor.

[0039] During operation of an apparatus according to the invention, there is a continuous transport of air through the drum wherein air from the exterior environment enters the drum interior space via an air inlet and exits it via an air outlet.

[0040] The air inlet comprises an air inlet tube that is present in the drum interior space where it is substantially parallel to the rotor rotational axis. The air inlet tube has a tube interior space that is in fluid communication with the exterior environment. For example, an opening at each end of the tube coincides with a corresponding opening in one of the terminal drum walls. It is also possible that only one end of the tube has an opening that coincides with an opening of a terminal drum wall.

[0041] The tube itself comprises one or more openings along the tube to allow that the tube interior space is in fluid communication with the drum interior space. These one or more openings are located in a longitudinal direction of the air inlet tube. In case there is one opening, then the opening is an elongated opening (e.g. a slit opening) that is present along the tube in the drum interior space. This embodiment is visualized in Figure 1 , where the air inlet (10) comprises an air inlet tube (10a) with an opening (11 ) all along the air inlet tube (10a). In case of multiple openings, then they are typically neighboring one another in a longitudinal direction along the air inlet tube. The multiple openings themselves may also be elongated, typically in the longitudinal direction along the air inlet tube. Thus, the one or more openings effectively form an elongated means for the passage of air, allowing the air inlet tube to produce an air stream in the form of an air knife.

[0042] The alignment of the air inlet tube with the rotor rotational axis causes that the rotor is along its rotational axis subject to a more less uniform air stream from the air inlet during operation of the apparatus. More specifically, the air inlet tube is positioned in such a way relative to the circumferential drum wall and the rotor that when air enters the drum interior space through the one or more openings at a certain air flow speed, the air travels as an airflow (or air knife) from the one or more openings towards the particle collision zone. Here, the air flow reaches the particle collision zone, affecting the trajectories of falling stony particles in a manner that they become more effectively hit by the rotor blades and / or that a larger number of falling stony particles lands in the particle collision zone because the stream of falling stony particles is narrowed as compared to not subjecting it to the air flow.

[0043] In an embodiment, the air inlet is adjustable in the sense that a volumetric flow rate of air passing through the inlet can be controlled, for example by changing a dimension of the air inlet.

[0044] The air outlet allows the exhaust of air from the drum interior space to the exterior environment. It typically comprises an opening in one or both terminal drum walls. In a preferred embodiment, the air outlet comprises an air outlet tube that is present in the drum interior space, the air outlet tube preferably being substantially aligned with the rotor rotational axis in the longitudinal drum direction (e.g. substantially parallel to the rotor). The air outlet tube has a tube interior space that is in fluid communication with the exterior environment. For example, an opening at each end of the tube coincides with a corresponding opening in one of the terminal drum walls. It is also possible that only one end of the tube has an opening that coincides with an opening of a terminal drum wall.

[0045] The air outlet tube itself, if present, comprises one or more openings along the tube to allow that the tube interior space is in fluid communication with the drum interior space; and ultimately that there is a fluid communication between the drum interior space and the exterior environment. It is herewith noted that fluid communication is considered to be possible also when an auxiliary means is present for creating an airflow out of the air outlet. The one or more openings of the air outlet tube are for example arranged similar to how the one or more openings in the air inlet tube are arranged.

[0046] During operation of the apparatus, air comprising dust that is generated in the drum passes through these one or more openings in the air outlet tube, travels through an interior space of the air outlet tube, and so becomes exhausted from the apparatus.

[0047] In an embodiment, the air outlet comprises a device for collecting dust from exhaust air that is exhausted from the air outlet. This means that dust and air are separated, so that air substantially void of dust can be obtained, which can subsequently be exhausted in the environment. Optionally, it is recycled by feeding it to the air inlet of the apparatus. Dust collected in this way is then suitable as e.g. a starting material in a subsequent process, for example for the manufacture of concrete.

[0048] In an embodiment, the air outlet is adjustable in the sense that a volumetric flow rate of air passing through the outlet can be controlled, for example by changing a dimension of the air outlet.

[0049] During operation of an apparatus according to the invention, there is a continuous feed of stony material into the drum and a continuous discharge of processed stony material out of the drum. The feeding into the drum occurs via the stony material inlet of the apparatus. The processed stony material typically comprises different fractions, not all of which leave the drum via the stony material outlet of the apparatus. As elaborated above, dust that has become airborne is exhausted via the air outlet. Other fractions such as sand, gravel, pebbles and other particles however usually leave the drum through the stony material outlet of the apparatus.

[0050] In a preferred embodiment, the stony material inlet as well as the stony material outlet comprises an opening in a terminal drum wall. This is especially advantageous when the terminal drum wall is stationary, because then the inlet and outlet do not have to be provided in moving elements (in particular not in rotating elements), which would be more complicated to realize. The apparatus may also comprise a plurality of stony material inlets and / or a plurality of stony material outlets. These may be located in both terminal drum walls, for example each terminal drum wall comprises a stony material inlet as well as a stony material outlet. This is in principle only the case in the absence of a tilting of the apparatus.

[0051] When an apparatus of the present invention is in operation, then particles of stony material are continuously affected by the rotating drum. Particles in the drum are first carried upwards by the rotating circumferential drum wall on which they rest, which is optionally facilitated by a certain surface structure at a surface of the circumferential drum wall, for example a surface relief such as a corrugated surface. The speed of rotation is chosen such that the particles get loose from the rotating circumferential drum wall when they have reached a certain height. This means that they are not continuously pressed against the circumferential drum wall by a centrifugal force during an entire revolution of the rotating circumferential drum wall. When the particles get loose from the wall, then they fall down in the drum interior space. In their fall, at least part of the particles enters the particle collision zone where they collide with a passing rotor blade. To this end, the rotor is arranged in the drum in a manner that allows the particles to land in the particle collision zone, given a certain speed of rotation of a particular circumferential drum wall. This mode of operation is visualized in Figure 2, which displays a cross-sectional view of an apparatus (1 ) of the invention. This view demonstrates how stony material (17a) that is being processed moves in the drum interior space under the influence of the drum (2) that rotates in a first direction (5a), and how the processed stony material (17) ultimately becomes discharged from the drum (2) via the stony material outlet (9). Also shown is an amount of dust (16) that has become airborne and that is exhausted via the air outlet (12).

[0052] Upon collision, the particles are swept away, e.g. they are expelled from the particle collision zone. Usually, this is accompanied by a certain degree of fragmentation of the particles. Once expelled or swept away, the fragmented particles may become airborne and travel out of the drum via an airflow that exhausts the drum via the air outlet. This usually concerns smaller and lighter particles. Larger and heavier particles that do not become airborne descend until they reach the rotating circumferential drum wall which subsequently drags them upwards again so that they can make another fall into the particle collision zone. After a number of such cycles of upwards dragging and downwards falling with a likely collision against a rotor blade or another particle, the fragmented stony particles ultimately collect at the stony material outlet and so leave the drum.

[0053] As outlined above, the number of cycles can be influenced by tilting the drum to a certain extent. During operation of the apparatus, the stony material is then added at the higher end of the drum and collected at the lower end of the drum. During rotation of the tilted drum, the stony particles ultimately move towards to the lower end where the stony material outlet is located. The smaller the tilt is during operation at a particular speed of rotation of the drum, the more cycles of upwards dragging and downwards falling are made before the stony material outlet is reached, the more collisions occur and the more fragmentation takes place. Conversely, the larger the tilt, the less cycles can be made and the less fragmentation occurs. Thus, the residence time of the stony particles in the drum can be influenced by tilting the drum. Depending on the type of stony material, the speed of rotation of the drum and the desired fragmentation, an appropriate tilt can be applied to the drum.

[0054] When an apparatus of the invention is in operation, then air enters the drum interior space via the air inlet as a result of a local underpressure in the drum at the air inlet relative to the pressure in the exterior environment, more specifically there is a local underpressure at the one or more openings that are present in the longitudinal direction of the air inlet tube. Such underpressure draws air from the outside environment into the drum interior space. The underpressure is generated by rotation of the rotor, which is positioned in such a way relative to the one or more openings that the underpressure is created at the one or more openings. The rotation also causes that air leaves the drum interior space via the air outlet. As a result, there is a net airflow from the air inlet to the air outlet. An effect of this airflow is that the trajectories of the falling particles can be better controlled than would be the case when the rotor rotates without causing a net airflow in the drum interior space. Another effect is that dust that is formed in or near the particle collision zone is taken up by the airflow, which allows it to travel towards the air outlet. This typically also has the effect that dust does not unnecessary loiter in the drum interior space, which would increase the chance that it gets mixed with the processed stony material that is collected at the stony material outlet (as collecting such mixture is undesired). Although the combined rotation of the rotor and the drum alone already causes the airflow as described above, also an auxiliary means may be present for creating the airflow. This may in principle be any device that is capable of contributing to the underpressure at the one or more openings of the air inlet tube. For example, a device may be applied that is arranged to actively exhaust air with dust from the drum interior space via the air outlet into the exterior environment, such as an airflow generator. In such case, there would be a general underpressure in the drum relative to the exterior environment.

[0055] Such auxiliary means for actively exhausting air with dust has the additional advantage that the dust is removed from the drum at a larger discharge flow-through. In this way, the stony material that is collected at the stony material outlet comprises less dust. Preferably, the airflow through such auxiliary means is so high that substantially all dust has escaped from the tumbling stony material at the moment that the tumbling stony material reaches the stony material outlet and collects there.

[0056] Fragmentation of the stony material occurs not only by collisions of the blades with particles of the stony material. In a preferred embodiment of the present invention, the fragmentation relies at least partly also on collisions between particles. This is in particular the case when particles that are swept away from the rotating rotor collide with other particles that are present in the drum but outside the collision zone. In this way, particle fragmentation not only occurs due to collision with the rotor blades. By making use of effective collisions between particles in the drum, the rotor gets spared because its direct involvement in fragmentation is reduced. This is advantageous, because the rotor is otherwise subjected to much more abrasion and attrition, prompting earlier replacement. Thus, an apparatus of the invention may be arranged to induce collisions of particles that are swept away from the rotating rotor with other particles, which other particles, as a result of the collision, undergo a fragmentation. In addition, also the particles that are swept away may undergo a fragmentation due to such collision.

[0057] An even better implementation of this principle is obtained when only smaller particles are hit by the rotor to become swept away, and when these expelled smaller particles collide with larger particles elsewhere in the drum. An advantage of this implementation is that the rotor blades are not hit by the larger and therefore heavier particles, but only by smaller particles that are lighter, which decreases wear of the rotor blades and so increases their lifetime.

[0058] This can be implemented by placing a separation device in the drum, which separation device is arranged to create a first stream of first falling particles and a second stream of second falling particles, wherein

[0059] - the first falling particles land in the particle collision zone to become swept away by the rotor blades;

[0060] - the second falling particles descend next to the particle collision zone;

[0061] - the first falling particles have a smaller size and / or a smaller mass than the second falling particles;

[0062] - the first falling particles that are swept away by the rotor blades collide with the second falling particles so that the first falling particles and / or the second falling particles become fragmented.

[0063] The separation device is preferably a sieve that is arranged in the drum to let pass smaller particles (through the sieve) which particles can then fall as the first falling particles, so that they can land in the particle collision zone. This means that the sieve blocks the larger particles which particles can then fall as the second falling particles so that they descend next to the particle collision zone. The separation device is typically positioned in an upper part of the drum and arranged as a stationary object that does not rotate together with the drum, so that it faces a stream of stony material. Usually, it is attached to the two terminal walls that are also stationary.

[0064] Figure 3 visualizes the presence of a separation device (13) in an apparatus (1 ) of the invention. Also shown is the route of the stony material (17a) that is being processed, in particular when it encounters the separation device (13) which generates first falling particles (14) that have passed the separation device (13) and second falling particles (15) that could not pass the separation device (13) due to their bigger size.

[0065] An advantage of an apparatus of the invention is that it can crush stony material and at the same time effectively separate generated dust from generated larger particles. This avoids the need to perform such separation as a separate post-processing step. When an apparatus of the invention is used to process concrete, then cement is the component that embodies the dust. The apparatus thus allows to recycle concrete and obtain its two main components separated from one another in one processing step, viz. cement and aggregates.

[0066] The invention further relates to a method for processing stony material with an apparatus as described hereabove. To this end, the drum is charged with stony material via the stony material inlet. Operating the apparatus then comprises causing the drum and the rotor to rotate in opposite directions. This on its turn causes the fragmentation of the stony material to form an airborne dust and a processed stony material. At the same time, air is allowed to become drawn into the drum interior space via the air inlet and to become exhausted from the drum interior space via the air outlet as an airflow. During operation, the processed stony material is continuously collected at the stony material outlet thereby leaving the drum, while the airborne dust continuously leaves the drum via the air outlet as a component of the airflow. The dust is then collected from the exhausted air, usually by means of a filter.

[0067] An airflow is generated by the rotation of the rotor in the rotating drum. Usually, this flow is sufficiently strong to draw air into the drum interior space via the air inlet and to exhaust it via the air outlet. If necessary, however, an auxiliary device may be applied that is arranged to actively exhaust the air with the dust. This may be an airflow generator, mounted at or near the air outlet.

[0068] The stony material that is applied in a method of the invention may in principle be any of the stony materials mentioned above. Usually, it is selected from the group of concrete materials, concrete waste materials, rocks, minerals, granite, asphalt, stones, cement clinkers and bricks.

[0069] In an advantageous method of the invention, the stony material comprises concrete. The generated dust then comprises cement and the processed stony material then comprises aggregate.

[0070] In another advantageous method of the invention, the stony material comprises asphalt. The collected stony material then comprises a loose mixture of stones and bitumen. These two components can then easily be separated from one another in a subsequent step. The mechanical operations in the drum that are performed on the initially added stony material advantageously knock off the stones from the bitumen, yielding a mixture of both as loose components. Any formed dust is transported to the air outlet via an airflow (usually, asphalt does not yield much dust upon fragmentation). It is an unexpected advantage that the processing of asphalt in an apparatus of the invention yields such a loose mixture of stones and bitumen that can conveniently be processed further (such as separating both components). The method works particularly well when the stones in the asphalt are made of granite.

Claims

CLAIMS1 . Apparatus (1 ) for processing stony material, the apparatus comprising- a drum (2) defining a drum interior space and an exterior environment outside the drum (2), wherein the drum (2) comprises a drum rotational axis and a circumferential drum wall (3) between two terminal drum walls (4a, 4b), which circumferential drum wall (3) is rotatably driven around the drum rotational axis in a first rotational direction (5a);- a rotor (6) that is present in the drum interior space, the rotor (6) having a rotor rotational axis and a plurality of rotor blades (6a) that define a particle collision zone (7) with respect to the rotor (6), which is a volume in which falling particles of the stony material can be hit by the rotor blades (6a) during operation of the apparatus (1 ); wherein the rotor (6) is rotatably driven around the rotor rotational axis in a second rotational direction (5b) that is opposite to the first rotational direction (5a);- a stony material inlet (8), allowing for an introduction of the stony material into the drum (2);- a stony material outlet (9), allowing for a discharge of processed stony material (17) out of the drum (2);- an air inlet (10), allowing for an inlet of air from the exterior environment into the drum interior space when there is, relative to the exterior environment, an underpressure in the drum (2) at the air inlet (10), wherein the air inlet (10) comprises an air inlet tube (10a) which o is present in the drum interior space where it is substantially aligned with the rotor rotational axis; o has one or more openings (1 1 ) in a longitudinal direction of the air inlet tube (10a); o is positioned relative to the circumferential drum wall (3) and the rotor (6) in such a way that when air enters the drum interior space via the air inlet (10), the air travels as an airflow from the one or more openings (1 1 ) towards the particle collision zone (7);- an air outlet (12) which is arranged to exhaust air comprising dust (16) from the drum interior space into the exterior environment;wherein the apparatus (1 ) is arranged to rotate the circumferential drum wall (3) at a rotational speed at which particles of stony material present in the drum interior space i) are carried upwards by the rotating circumferential drum wall (3); ii) subsequently get loose from the rotating circumferential drum wall (3) when they have reached a certain height; and iii) subsequently fall down in the drum interior space; and wherein the rotor (6) is positioned in the drum (2) in such way that, during rotation of the circumferential drum wall (3) and rotation of the rotor (6), the falling particles of stony material land in the particle collision zone (7) of the rotating rotor (6) so that they collide with a rotor blade (6a), thereby causing that the particles of stony material are swept away from the rotating rotor (6) and that the particles fragmentize.

2. Apparatus (1 ) according to claim 1 , wherein the air outlet (12) comprises a device for the active exhaust of air from the drum interior space.

3. Apparatus (1 ) according to claim 1 or 2, wherein the air outlet (12) comprises a device for collecting dust (16) from exhaust air that is exhausted from the air outlet (12).

4. Apparatus (1 ) according to any one of claims 1 -3, wherein the air outlet (12) comprises an air outlet tube which is present in the drum interior space and which air outlet tube has one or more openings in a longitudinal direction of the air outlet tube.

5. Apparatus (1 ) according to any one of claims 1-4, wherein sweeping the particles of stony material away from the rotating rotor (6) causes the particles to have a collision with other particles, which other particles, as a result of the collision, undergo a fragmentation.

6. Apparatus (1 ) according to any one of claims 1-5, wherein the apparatus (1 ) comprises a separation device (13) that is arranged to create a first stream of first falling particles (14) and a second stream of second falling particles (15), wherein- the first falling particles (14) land in the particle collision zone (7) to become swept away by the rotor blades (6a);- the second falling particles (15) descend next to the particle collision zone (7);- the first falling particles (14) that are swept away collide with second falling particles (15) so that the first falling particles (14) and / or the second falling particles (15) become fragmented.

7. Apparatus (1 ) according to claim 6, wherein the first falling particles (14) have a smaller size and / or a smaller mass than the second falling particles (15).

8. Apparatus (1 ) according to claim 6 or 7, wherein the separation device (13) comprises a sieve that is arranged in the drum (2) to let pass the first falling particles (14) so that they can land in the particle collision zone (7); and to block the second falling particles (15) so that they descend next to the particle collision zone (7).

9. Apparatus (1 ) according to any one of claims 1-8, wherein the drum rotational axis is oriented substantially horizontally or wherein the drum rotational axis is tilted with an angle that is between 0° and 25°, in particular between 5° and 15°.

10. Apparatus (1 ) according to any one of claims 1-9, wherein the stony material is selected from the group of concrete materials, concrete waste materials, rocks, minerals, granite, asphalt, stones, cement clinkers and bricks.11 . Apparatus (1 ) according to any one of claims 1 -10, wherein the circumferential drum wall (3) has a corrugated surface facing the drum interior space.

12. Apparatus (1 ) according to any one of claims 1-11 , wherein the circumferential drum wall (3) rotates relative to both terminal drum walls (4a, 4b).

13. Apparatus (1 ) according to any one of claims 1 -12, wherein the air inlet (10), the air outlet (12), the stony material inlet (8) and the stony material outlet (9) are contained in one or both terminal drum walls (4a, 4b).

14. Method for processing stony material, comprising- providing an apparatus (1 ) according to any one of claims 1-13;- charging the drum (2) with stony material via the stony material inlet (8);- causing the drum (2) and the rotor (6) to rotate in opposite directions (5a, 5b), to thereby fragmentize the stony material to form a dust (16) that is airborne and a processed stony material (17) that is capable of becoming collected at the stony material outlet (9);- allowing air to become drawn into the drum interior space via the air inlet (10) and to become exhausted from the drum interior space via the air outlet (12), wherein the exhausted air comprises the dust (16);- collecting the processed stony material (17) from the drum (2) via the stony material outlet (9);- collecting the dust (16) from the exhausted air.

15. Method according to claim 14, wherein the stony material comprises concrete, wherein the dust (16) comprises cement and wherein the processed stony material (17) comprises aggregate.

16. Method according to claim 14, wherein the stony material comprises asphalt.

17. Method according to any one of claims 14-16, wherein air is actively exhausted from the drum interior space by using an airflow generating device which creates an underpressure in the drum (2) relative to the exterior environment.

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