FIELD OF THE INVENTION

The invention relates to an apparatus for separating sea shells from a beach garbage mixture. The invention further relates to a method for separating sea shells from a beach garbage mixture.

BACKGROUND OF THE INVENTION

The present invention relates to the field of processing mixed recyclable materials. The invention also relates to the field of beach sanitation.

Beaches all over the world are polluted both by a mixture of marine garbage and/or recreational garbage.

A garbage mixture collected from a beach mainly consists out of: fishery related garbage, food and drink related garbage, smoking related garbage, sanitary related garbage, offshore related garbage, domestic garbage, packaging and work related materials, shipping related garbage, industrial and transport related garbage and sea shells (which is unwanted in the collected garbage).

It is the responsibility of coastal municipalities to sanitize the beaches and to collect the scattered mixture of garbage. In this way, the beaches are kept attractive for tourists and the negative effects on the environment and marine species are reduced. In order to clean the larger beaches, so called beach cleaners are used.

Most beach cleaners are tractor-pulled screening machines that use a combination of raking and screening techniques to collect and separate a mixture of garbage from the beach sand. The screened-out material that results from this process, consists of material that cannot pass through the mesh of the screen and forms the overflow of the screen. This material is collected in a small collection container within the beach cleaner. If this container is full, it is deposited within a larger collection container on top of the beach cleaner. When both containers are full the beach cleaner deposits the collected material in a garbage truck that is present at the beach or directly onto a garbage disposal site. However, in the current existing beach cleaners, together with the collected mixture of garbage, large quantities of sea shells are also taken, which is undesirable for multiple reasons. First, sea shells contribute to a natural and ecological beach and help in preventing beach erosion by their sand clinching characteristics. In this way, the sea shells indirectly decrease the amount of expensive beach nourishments needed for eroding coasts. Also, the processing costs involved in the cleaning procedure of the beach may be brought down if the sea shells are no longer collected by the beach cleaners as less intermediate disposing will be needed. In this way, the costs and time needed for the sanitation can be reduced. However, currently there are no beach cleaners capable of making a distinction between the sea shells and a beach related mixture of garbage.

EP 1342832 discloses a method for recycling paper using a combination of: screen, screw conveyor and a double zigzag wind sifter paper recycling apparatus.

US20030062294 Al, US 6648145 B2, EP 1399274 Bl and WO

1989000893 Al disclose a method using a disc screen wherein large material fraction is disposed by the disc screen.

EP2832457 discloses a method using two parallel zig zag wind sifters to increase the throughput.

Finally, US 6237816 B l discloses an apparatus comprising a rotary valve and method of operating it.

SUMMARY OF THE INVENTION

It would be advantageous to have an improved apparatus for separating sea shells from a beach garbage mixture. To better address this concern, a first aspect of the invention provides an apparatus for separating sea shells from a garbage mixture comprising a first air classifier and a second air classifier, wherein the first air classifier comprises a first conduit and first separating means, and wherein the second air classifier comprises a second conduit and second separating means, wherein the first conduit comprises a first inlet fluidly connected to the first conduit, a first outlet fluidly connected to the first conduit, and a second outlet fluidly connected to the first conduit , wherein the first inlet is further arranged to receive the garbage mixture, wherein the first separating means is arranged to introduce a first air flow into the first conduit, and to separate the garbage mixture into a first material fraction, discharged through the second outlet, and a first mixture, wherein the first mixture comprises a sea shell fraction and a second material fraction and wherein the first mixture is discharged through the first outlet, wherein the second conduit comprises a second inlet fluidly connected to the second conduit, a third outlet fluidly connected to the second conduit and a fourth outlet fluidly connected to the second conduit, wherein the second inlet is furthermore fluidly connected to the first outlet of the first air classifier and is arranged to receive the first mixture from the first outlet of the first air classifier, wherein the second separating means is arranged to introduce a second air flow into the second conduit, and to separate the first mixture into the second material fraction discharged through the third outlet, and the sea shell fraction discharged through the fourth outlet,

• wherein the first air flow and the second air flow are such that the air flow force acting on the first mixture overcomes the gravity force acting on the first mixture thereby discharging the first mixture through the first outlet, the gravity force acting on the first material fraction overcomes the air flow force acting on the first material fraction thereby discharging the first material fraction through the second outlet, the air flow force acting on the second material fraction overcomes the gravity force acting on the second material fraction thereby discharging the second material fraction through the third outlet, and the gravity force acting on the sea shell fraction overcomes the air flow force acting on the sea shell fraction thereby discharging the sea shell fraction through the fourth outlet;

• or wherein the first air flow and the second air flow are such that the gravity force acting on the first mixture overcomes the air flow force acting on the first mixture thereby discharging the first mixture through the first outlet, the air flow force acting on the first material fraction overcomes the gravity force acting on the first material fraction thereby discharging the first material fraction through the second outlet, the gravity force acting on the second material fraction overcomes the air flow force acting on the second material fraction thereby discharging the second material fraction through the third outlet, and the air flow force acting on the sea shell fraction overcomes the gravity force acting on the sea shell fraction thereby discharging the sea shell fraction through the fourth outlet. By using multiple separation steps, this allows to make a distinction between sea shells and the mixture of garbage in the collected material. In this way, sea shells can be separated and returned to the beach. The apparatus can be used as an add- on to beach cleaners or used as a standalone device.

Currently, beach cleaners are not capable of making a classification between the garbage mixture and sea shells, and consequently large quantities of sea shells are collected along with the garbage mixture. By combining and integrating the current method and apparatus within a beach cleaner, the sea shells can be separated from the garbage mixture and returned to the beach.

This avoids unnecessary depositing of sea shells on the dump site, resulting in decreased processing costs of the collected material by the beach cleaner and thus a cheaper cleaning process.

Also less intermediate depositing will be needed, because returning the sea shells to the beach while collecting the garbage mixture implies that the container fills up less quickly and depositing the collection container of the beach cleaner when this is full takes time and slows down the cleaning process.

Sea shells will contribute to prevent beach erosion due to their sand clinching characteristics. In this way, the amount of expensive beach nourishments needed for eroding coasts is decreased.

I.e., this allows to decrease processing costs of the garbage disposal (less weight), to decrease cleaning time needed, decrease costs of the beach cleaning process, decrease beach erosion rate, maintain a more natural and ecological beach environment and to preserve the eco-system and geological beach processes.

The apparatus may further be provided with a collector with an integrated disc screen at its bottom which takes the largest garbage out of the mixed garbage and sea shell material. The disc-screen uses differences in size of the collected material; the sea shells and smaller garbage are separated from the larger garbage. The sea shells are separated from the smaller garbage in the next step.

The separating means may comprise a zigzag conduit for separating the smaller material into a small heavy garbage fraction, a small light garbage fraction and a sea shell fraction. In this way, the garbage is separated into 4 fractions after the beach cleaner has collected it. Afterwards, the three parts of waste (i.e., the larger garbage, the small heavy garbage fraction, and the small light garbage fraction) may be combined again in one large container for disposal.

The separating means are configured to perform the separation based on differences in size, shape, wall thickness and specific weight. I.e., the separating means may use an air flow to separate the material based on size, shape, wall thickness and specific weight. As such the beach cleaner does no longer remove and collect the sea shells from the beach, the processing costs related with the disposing of material at the dumpsite are decreased, the work flow of the cleaning process with the beach cleaner is increased and the beach erosion rate of the coast is reduced since the sand clinching characteristics of sea shells prevent sand drift.

The volumetric air flow rate of the first separating means may be higher than that of the second. In this way, the heavier/larger/thicker wall thickness garbage is separated in the first separating means and the lighter/smaller/thinner wall thickness garbage is separated in the second separating means.

On the other hand, the volumetric air flow rate of the first separating means may be lower than that of the second. In this way, the lighter/smaller/thinner wall thickness garbage is separated in the first separating means and the

heavier/larger/thicker wall thickness garbage is separated in the second separating means. I.e., the configuration of the separating means can be reversed. In that way, first the lighter garbage fraction would be taken out and after that the sea shells would be separated as“light fraction” from the heavy garbage fraction. This provides the additional advantage that the sea shells can be powerfully ejected out of the beach cleaner apparatus and evenly spread out over the beach (resembling the natural spreading of the sea shells).

In order to differentiate the garbage with multiple thresholds, multiple separating means comprising zigzag conduits could be placed in series each with a different volumetric air flow. A higher volumetric airflow will lead to a larger percentage of the garbage mixture ending up in the“lighter fraction”.

Furthermore a roller separator could be added to purify the sea shell fraction and remove any cork or other round foreign objects that should not be included within the sea shell fraction and that may not have been separated by the previous steps. Also a magnet could be added to further purify the sea shell fraction and remove any metal soda bottle caps or other metal objects that should not be included within the sea shell fraction and that may not have been separated by the previous steps.

This allows for separation of sea shells out of a large variety of different types of beach garbage.

The possibility to incorporate the apparatus within a beach cleaner enables the beach cleaner to perform mobile separation of sea shells during operation directly on the beach.

The apparatus may be provided with an expansion chamber for reducing the air flow inside of the conduits.

The apparatus may comprise a screw conveyor or a rotatory valve used for material transportation in between separation means.

The width of the zigzag conduits may be between 100 millimeters and 500 millimeters. In one embodiment, the width of the zigzag conduit may be 250 millimeters. However, the zigzag conduits may have any suitable width. The width of the zigzag conduits may be based on the amount of garbage that can be separated per hour.

The angle of the zigzags of the zigzag conduits may be 120 degrees. However, the zigzags may have any suitable angle.

The number of zigzags of the zigzag conduits may be between 2 and 5. In one embodiment, the number of zigzags of the zigzag conduits may be 3.

However, the number of zigzags of the zigzag conduits may be any suitable number. Every bend (i.e., every zigzag) in a zigzag conduit is a separator in itself. So every zigzag contributes to an increased separation effectiveness.

Furthermore, the zig zag conduits may be equal or different to each other.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention are apparent from and will be explained with reference to the embodiments described hereinafter. In the drawings,

Fig. 1 is a diagram schematically illustrating the classification of different materials of small size from a beach.

Fig. 2A illustrates an apparatus for separating sea shells from a garbage mixture according to a first embodiment of the invention. Fig. 2B illustrates an apparatus for separating sea shells from a garbage mixture according to a second embodiment of the invention.

Fig. 3 A illustrates further details of the apparatus for separating sea shells from a garbage mixture of Fig. 2A.

Fig. 3B illustrates further aspects of the apparatus for separating sea shells from a garbage mixture of Fig. 2B.

Fig. 4 is a diagram schematically illustrating a pre-classification of different materials of small size and large size from a beach.

Fig. 5A illustrates an apparatus for separating sea shells from a garbage mixture according to a third embodiment of the invention.

Fig. 5B illustrates an apparatus for separating sea shells from a garbage mixture according to a fourth embodiment of the invention.

Fig. 5C illustrates a screening unit for separating large size materials from beach garbage.

Fig. 6A illustrates further aspects of the apparatus for separating sea shells from a garbage mixture of Fig. 5 A.

Fig. 6B illustrates further aspects of the apparatus for separating sea shells from a garbage mixture of Fig. 5B.

Fig. 7 illustrates further aspects of the apparatus for separating sea shells from a garbage mixture of Fig. 6A.

Fig. 8 shows a different view of the apparatus for separating sea shells from a garbage mixture of Fig. 7.

Fig. 9 illustrates a beach cleaner vehicle comprising the apparatus for separating sea shells from a garbage mixture of Fig. 6A.

DETAILED DESCRIPTION OF EMBODIMENTS

Although the system is described herein in detail, it will be understood that for many features described herein, alternative solutions may be used without departing from the scope of the claims.

Fig. 1 is an illustration of a classification of the small fraction of a garbage mixture of different materials from a beach.

In Fig. 1, it is shown that the garbage mixture collected from a beach may contain sea shells 1, a heavy weight material fraction 5 and a light weight material fraction 3, wherein the difference between the sea shells, the material fraction 5 and the material fraction 3 is based on differences in size, shape, wall thickness and specific weight.

The light weight material 3 may comprise material having a density and/or a size in the maximum dimension and/or a thickness and/or a weight between the following ranges:

440 kilogram s/meters ³ < density < 1400 kilogram s/meters ³

1 millimeters < size in the maximum dimension < 40 millimeters

0.1 millimeters < thickness < 7 millimeters

0.4 grams < weight < 5 grams

Each of the sea shells 1 may have a density and/or a size in the maximum dimension and/or a thickness and/or a weight between the following ranges:

600 kilogram s/meters ³ < density < 800 kilogram s/meters ³

10 millimeters < size in the maximum dimension < 40 millimeters

0.1 millimeters < thickness < 1.5 millimeters

2 grams < weight < 15 grams

The heavy weight material 5 may comprise material having a density and/or a size in the maximum dimension and/or a thickness and/or a weight between the following ranges:

2200 kilogram s/meters ³ < density < 8500 kilogram s/meters ³

10 millimeters < size in the maximum dimension < 30 millimeters

0.5 millimeters < thickness < 30 millimeters

2 grams < weight < 100 grams

The light weight material 3 may comprise, for instance, cigarette butts and/or pieces of plastic.

Each one of the cigarette butts may be have a density and/or a size in the maximum dimension and/or a thickness and/or a weight between the following ranges:

440 kilograms/meters ³ < density < 800 kilogram s/meters ³

7 millimeters < size in the maximum dimension < 30 millimeters

5 millimeters < thickness < 7 millimeters

0.4 grams < weight < 1.0 grams

Each one of the pieces of plastic may have a density and/or a size in the maximum dimension and/or a thickness and/or a weight between the following ranges: 900 kilogram/meters ³ < density < 1400 kilogram/meter ³

1 millimeters < size in the maximum dimension < 40 millimeters

0.1 millimeters < thickness < 1 millimeters

0.5 grams < weight < 5.0 grams

The heavy weight material 5 may comprise, for instance, stones and/or pieces of metal and/or pieces of glass.

Each one of the pieces of glass may have a density and/or a size in the maximum dimension and/or a thickness and/or a weight between the following ranges:

2500 kilogram/meter ³ < density < ± 2700 kilogram/meter ³

10 millimeters < size in the maximum dimension< 30 millimeters

1 millimeters < thickness < 3 millimeters

10 grams < weight < 30 grams

Each one of the stones may have a density and/or a size in the maximum dimension and/or a thickness and/or a weight between the following ranges:

2200 kilogram/meter ³ < density < 2800 kilogram/meter ³

10 millimeters < size in the maximum dimension < 30 millimeters

5 millimeters < thickness < 30 millimeters

20 grams < weight < 100 grams

Each one of the pieces of metal may have a density and/or a size in the maximum dimension and/or a thickness and/or a weight between the following ranges:

7500 kilogram/meter ³ < density < 8500 kilogram/meter ³

10 millimeters < size in the maximum dimension < 30 millimeters

0.5 millimeters < thickness < 1 millimeters

2 grams < weight < 5 grams

Fig. 2A illustrates an apparatus for separating sea shells from a garbage mixture according to a first embodiment of the invention.

The apparatus for separating sea shells from a garbage mixture of Fig. 2A comprises a first air classifier 7 and a second air classifier 9.

The first air classifier 7 comprises an inlet 11, a first outlet 16 and a second outlet 15. The first air classifier 7 is arranged to receive a garbage mixture through the first inlet 11, and to classify the garbage mixture into a material fraction 5 and a mixture, wherein the mixture comprises a sea shell fraction 1 and a material fraction 3. The material fraction 5 is discharged through the second outlet 15 and the mixture is discharged through the first outlet 16.

The second air classifier 9 comprises an inlet 17, a first outlet 19 and a second outlet 21. The inlet 17 of the second air classifier 9 is fluidly connected to the first outlet 16 of the first air classifier 7. The second air classifier 9 is arranged to receive at the inlet 17 the mixture discharged by the first air classifier 7 through the first outlet 16. The second air classifier 9 is further arranged to classify the mixture received through the inlet 17 into a material fraction 3 and a sea shell fraction 1. The material fraction 3 is discharged through the first outlet 19 and the sea shell fraction 1 is discharged through the second outlet 19.

Fig. 2B illustrates an apparatus for separating sea shells from a garbage mixture according to a second embodiment of the invention.

The apparatus for separating sea shells from a garbage mixture of Fig. 2B comprises a first air classifier 8 and a second air classifier 13.

The first air classifier 8 comprises an inlet 23, a first outlet 27 and a second outlet 25. The first air classifier 8 is arranged to receive a garbage mixture through the first inlet 23, and to classify the garbage mixture into a material fraction 3 and a mixture, wherein the mixture comprises a sea shell fraction 1 and a material fraction 5. The material fraction 3 is discharged through the second outlet 25 and the mixture is discharged through the first outlet 27.

The second air classifier 13 comprises an inlet 29, a first outlet 31 and a second outlet 33. The inlet 29 of the second air classifier 13 is fluidly connected to the first outlet 27 of the first air classifier 8. The second air classifier 13 is arranged to receive at the inlet 29 the mixture discharged by the first air classifier 8 through the first outlet 27. The second air classifier 13 is further arranged to classify the mixture received through the inlet 29 into a material fraction 5 and a sea shell fraction 1. The material fraction 5 is discharged through the first outlet 31 and the sea shell fraction 1 is discharged through the second outlet 33.

Fig. 3A illustrates further aspects of the apparatus for separating sea shells from a garbage mixture of Fig. 2 A in which same reference number refer to the same components as in Fig.2A.

The first air classifier 7 of the apparatus for separating sea shells from a garbage mixture of Fig. 3 A comprises separating means 38 and a conduit 35. The conduit 35 is fluidly connected to the inlet 11, to the first outlet 16 and to the second outlet 15. The conduit 35 is arranged to receive the garbage mixture through the inlet 11. The conduit 35 comprises a zig zag shape. The separating means 38 is arranged to introduce a first air flow into the conduit 35 for separating the garbage mixture into the material fraction 5, which is discharged through the second outlet 15, and the mixture comprising the sea shell fraction, which is discharged through the first outlet 16. The first air classifier 7 further comprises rotatory valve 10 arranged to regulate the flow of the garbage mixture entering into the conduit 35 through the inlet 11.

The second air classifier 9 of the apparatus for separating sea shells from a garbage mixture of Fig. 3 A comprises further separating means 40 and a conduit 37. The conduit 35 is fluidly connected to the inlet 17, to the first outlet 19 and to the second outlet 21. The conduit 37 is arranged to receive the mixture from the first outlet 16 of the first air classifier 7 through the inlet 17. The conduit 37 comprises a zig zag shape. The separating means 40 is arranged to introduce a second air flow into the conduit 37 for separating the mixture into the material fraction 3, which is discharged through the first outlet 19, and the sea shell fraction 1, which is discharged through the second outlet 21.

The second air classifier 9 further comprises rotatory valve 20 arranged to regulate the flow of the mixture entering into the conduit 37 through the inlet 17.

The apparatus for separating sea shells from a garbage mixture of Fig.

3 A works as follows. The garbage mixture enters the first air classifier 7 through the inlet 11. The rotatory valve 10 provides a steady flow of the garbage mixture inside of the conduit 35. The separating means 38 are arranged to introduce a first air flow such that the air flow produces a force which is acting on the mixture. This overcomes the gravity force acting on the mixture when it falls inside of the conduit 35 through the inlet 11. In this way, the mixture is pushed upwards the conduit 35 and is discharged through the first outlet 16. On the other hand, the gravity force acting on the material fraction 5 overcomes the air flow force acting on that material fraction 5. In this way, the material fraction 5 falls down through the conduit 35 and is discharged through the second outlet 15. The mixture, which has been pushed upwards the conduit 35 and discharged through the first outlet 16, enters into the second air classifier through the inlet 17 which is connected to the first outlet 16 of the first air classifier 7. The rotatory valve 20 provide a steady flow of the mixture inside of the conduit 37. The separating means 40 are arranged to introduce a second air flow such that the air flow produces a force which acting on the material fraction 3 overcomes the gravity force acting on the material fraction 3 when it falls inside of the conduit 37 through the inlet 17. In this way, the material fraction 3 is pushed upwards the conduit 37 and is discharged through the first outlet 19. On the other hand, the gravity force acting on the sea shell fraction 1 overcomes the air flow force acting on the sea shell fraction 1. In this way, the sea shell fraction 1 falls down through the conduit 37 and is discharged through the second outlet 21.

The apparatus for separating sea shell from garbage mixture of Fig. 3 A and 3B may be configured for separating the sea shells from a garbage mixture as the one explained with reference to Fig. 1. 1.e, the first air flow and/or the second air flow and/or the first conduit and/or the second conduit may have parameters such that an air pressure is formed inside of the first and/or the second conduit able to separate garbage mixture comprising a heavy weigh material 5, a light weight material 3 and sea shells 1 having a density and/or a maximum size and/or a thickness and/or a weight within the parameters defined with respect to Fig. 1.

In this respect, the parameters may be such that the first conduit (zig-zag sifter) in Fig. 3A (the second zig-zag sifter in Fig. 3B) may receive from the first air flow (the second air flow of Fig. 3B) an air volume ratio between 5000 metersVhour and 7500 metersVhour.

The parameters may be also such that second conduit (zig-zag sifter) in Fig. 3 A (the first zig-zag sifter in Fig. 3B) may receive from the second air flow (the first air flow of Fig. 3B) an air volume ratio between 2500 metersVhour and 3000 metersVhour.

Among the parameters for having a separation according to the materials described in Fig. 1, the width of the rectangular cross section of the zigzag conduits may be between 100 millimeters and 500 millimeters, and the length of the rectangular cross section of the zigzag conduits may be between 100 millimeters and 200 millimeters. In one embodiment, the width of the zigzag conduit may be 260 millimeters and the length may be 200 millimeters. In one embodiment, the width of the zigzag conduit may be 260 millimeters.

The angle of the zigzags of the zigzag conduits may be 120 degrees.

The number of zigzags of the zigzag conduits may be between 3 and 6.

In one embodiment, the number of zigzags of the zigzag conduits may be 4. Fig. 3B illustrates further aspects of the apparatus for separating sea shells from a garbage mixture of Fig. 2B in which the same reference numbers refer to the same components as in Fig.2B.

The first air classifier 8 of the apparatus for separating sea shells from a garbage mixture of Fig. 3B comprises separating means 42 and a conduit 39. The conduit 39 is fluidly connected to the inlet 23, to the first outlet 27 and to the second outlet 25. The conduit 39 is arranged to receive the garbage mixture through the inlet 23. The conduit 39 comprises a zig zag shape. The separating means 42 are arranged to introduce a first air flow into the conduit 39 for separating the garbage mixture into the material fraction 3, which is discharged through the second outlet 25, and the mixture comprising the sea shell fraction, which is discharged through the first outlet 27. The first air classifier 8 further comprises rotatory valve 12 arranged to regulate the flow of the garbage mixture entering into the conduit 39 through the inlet 23.

The second air classifier 13 of the apparatus for separating sea shells from a garbage mixture of Fig. 3B comprises further separating means 44 and a conduit 41. The conduit 41 is fluidly connected to the inlet 29, to the first outlet 31 and to the second outlet 33. The conduit 41 is arranged to receive the mixture from the first outlet 29 of the first air classifier 11 through the inlet 29 of the second air classifier 13. The conduit 41 comprises a zig zag shape. The separating means 44 are arranged to introduce a second air flow into the conduit 41 for separating the mixture into the material fraction 5, which is discharged through the first outlet 31, and the sea shell fraction 1, which is discharged through the second outlet 33.

The second air classifier 13 fiirther comprises rotatory valve 14 arranged to regulate the flow of the mixture entering into the conduit 41 through the inlet 29.

The apparatus for separating sea shells from a garbage mixture of Fig.

3B works as follows. The garbage mixture enters the first air classifier 8 through the inlet 23. The rotatory valve 12 provides a steady flow of the garbage mixture inside of the conduit 39. The separating means 42 are arranged to introduce a first air flow such that the air flow produces a force which acting on the material fraction 3 overcomes the gravity force acting on the material fraction 3 when it falls inside of the conduit 39 through the inlet 23. In this way, the material fraction 3 is pushed upwards the conduit 39 and is discharged through the second outlet 25. On the other hand, the gravity force acting on the mixture overcomes the air flow force acting on the mixture. In this way, the mixture falls down through the conduit 41 and is discharged through the second outlet 27. The mixture enters into the second air classifier 13 through the inlet 29 which is connected to the first outlet 27 of the first air classifier 8. The rotatory valve 14 provides a steady flow of the mixture inside of the conduit 41. The separating means 44 are arranged to introduce a second air flow such that the air flow produces a force which acting on the sea shell fraction 1 overcomes the gravity force acting on the sea shell fraction 1 when it falls inside of the conduit 41 through the inlet 29. In this way, the sea shell fraction 1 is pushed upwards the conduit 41 and is discharged through the second outlet 33. On the other hand, the gravity force acting on the material fraction 5 overcomes the air flow force acting on the material fraction 5. In this way, the material fraction 5 falls down through the conduit 41 and is discharged through the first outlet 31.

Fig. 4 is a diagram illustrating a pre-classification of different materials from a beach.

In Fig. 4 it is shown that the garbage collected from a beach may contain large garbage 43 and small garbage, wherein the small garbage comprises sea shells 1, a material fraction 5 and a material fraction 3.

Fig. 5A illustrates an apparatus for separating sea shells from garbage collected from a beach according to a third embodiment of the invention in which same reference number refer to the same components as in Fig. 2A.

The apparatus for separating sea shells from garbage collected from a beach of Fig. 5 A is identical to the one of Fig. 2A with the addition of a screening unit 45 wherein the screening unit 45 comprises further an inlet 47, a first outlet 49 and a second outlet 51. The screening unit 45 is arranged to receive garbage collected from a beach comprising large garbage 43 and small garbage at the inlet 47. The screening unit 45 is further arranged to separate the large garbage 43 from the small garbage wherein the large garbage 43 is discharged through the first outlet 49 and the small garbage is discharged through the second outlet 51. The first air classifier 7 is arranged to receive at the inlet 11 the small garbage discharged by the screening unit 45 through the first outlet 51, wherein the small garbage is the garbage mixture that will be separated by the first air classifier 7 into the material fraction 5 and the mixture comprising sea shells. Fig. 5B illustrates an apparatus for separating sea shells from garbage collected from a beach according to a fourth embodiment of the invention in which same reference number refer to the same components as in Fig.2B.

The apparatus for separating sea shells from garbage collected from a beach of Fig. 5B is identical to the one of Fig. 2B with the addition of a screening unit 45 of Fig. 5 A. The first air classifier 8 is arranged to receive at the inlet 23 the small garbage discharged by the screening unit 45 through the first outlet 51, wherein the small garbage is the garbage mixture that will be separated by the first air classifier 8 into the material fraction 3 and the mixture comprising sea shells.

Fig. 5C illustrates a screening unit according to one embodiment of the invention. The screening unit comprises a number of shafts 50 wherein each shaft comprises a number of double discs 52 interacting with each other and thereby fonning closures 54. 1.e., the shafts and the discs are arranged such that a number of closures 54 are formed between the discs. The size of the closures is such that the sea shells can pass through them and the larger garbage is separated.

Fig. 6A illustrates further aspects of the apparatus for separating sea shells from garbage collected from a beach of Fig. 5 A in which the same reference numbers refer to the same components as in Fig. 5A and 3 A.

The apparatus for separating sea shells from garbage collected from a beach of Fig. 6A is identical to the one of Fig. 3 A with the addition of the screening unit 45 wherein the screening unit 45 comprises further the inlet 47, the first outlet 49 and the second outlet 51.

Fig. 6B illustrates further aspects of the apparatus for separating sea shells from a garbage mixture of Fig. 5B in which the same reference numbers refer to the same components as in Fig. 5B and 3B.

The apparatus for separating sea shells from garbage collected from a beach of Fig. 6B is identical to the one of Fig. 3B with the addition of the screening unit 45 wherein the screening unit 45 comprises further the inlet 47, the first outlet 49 and the second outlet 51.

Fig. 7 illustrates further aspects of the apparatus for separating sea shells from a garbage mixture of Fig. 6A in which the same reference numbers refer to the same components as in Fig. 6A. Fig. 7 is a different view of Fig. 8 and everything that will be say for Fig. 7 applies to Fig. 8.

Fig. 9 illustrates a beach cleaner vehicle 100 comprising the apparatus for separating sea shells from a garbage mixture of Fig. 7 and 8 in which the same reference numbers refer to the same components as in Fig. 7 and 8.

The apparatus for separating sea shells from garbage collected from a beach of Fig. 7 comprises a collector 61 and a disc screen 63 having a number of rotating double discs 52.

The garbage collected from a beach consisting out of sea shells and garbage is fed into the collector 61. The disc screen 63 is arranged at the bottom of the collector 61. The disc screen 63 is arranged to remove the large garbage 43 from the garbage collected from a beach as an overflow. The disc screen 63 comprises a vertically inclined side and rotating disc assemblies 64 which collaborate in order to transport the large garbage 43 to one side of the collector 61. The collector 61 comprises opening 65 on one side. The opening 65 is configured to enable the large garbage 43 to leave the collector 61. The collector 61 further comprises a rubber baffle 67 which is positioned at the opening 65 in order to ensure that only the material that is in direct contact with the rotating discs 52 of the disc screen 63 leave the collector 61 of the apparatus. In this way, the chance of smaller particles leaving the collector on top of the large garbage 43 is decreased in order to improve separation effectiveness.

The small garbage together with the sea shells falls in between the openings 65 of the shafts of the disc screen 63 and the closures 54 between the interlocking discs (rotating discs assemblies) 52 as underflow. Due to the agitation of the material by the rotating discs 52, the disc screen 63 is capable of reaching a high separation efficiency. The small garbage that has passed through the disc screen 63 is collected in a funnel shaped collector underneath the disc screen 61. The small garbage is transported to the entry of the first separating means 7 by either a first rotary valve 72 or screw conveyor. This guaranties an air tight connection to the entry of the first separating means 7. The volumetric air flow rate is the main separating criterion of a zigzag wind sifter as the first separating means 7. An uprising air flow (stronger compared to the airflow of the second separating means 9) within the conduit 35 takes along the lighter garbage fraction together with the sea shells to the top end of the conduit 35 of the first separating means 7, while the heavier garbage fraction settles in against the uprising air stream and is disposed at the bottom of conduit 35.

The first 7 and the second 9 separating means consists of a multi-deck zigzag channel. The conduits 35 and 37 comprise a number of zigzags which can be considered as a sequence of single cross flow separators. A higher number of zigzags will result in a higher effectiveness of the separation. The first 7 and the second 9 separating means are fed from the middle of the conduits 35 and 37. Light, small material is entrained in the upward flowing air and large and heavy material falls down by gravitational forces.

The lighter garbage fraction and the sea shells settle in an expansion chamber 75 where they accumulate and are collected by a rotary valve or screw conveyor 73. The airflow generated for the first separating means 7 leaves the expansion chamber through a screen 79. Any material still entrained within the air flow is stopped by this screen, preventing material exiting the separation system at the wrong place. The second separating means 9 uses a lower volumetric air flow than the first separating means 7 causing the sea shells to settle in against the uprising airflow as the heavier fraction and leaves the second separating means 9 at the bottom 81. The lighter garbage is blown out at the top 83 of the second separating means 9. The apparatus thus separates the garbage collected from a beach in a total of 4 fractions (large, small heavy and small light garbage fraction) and a sea shell fraction.

When the apparatus for separating sea shells from a garbage mixture of Fig. 7 and 8 is mounted on a beach cleaner vehicle as in Fig. 9, the beach cleaner vehicle 100 comprises further a collection container 91. The beach cleaner vehicle first collects the material comprising the large and the small size garbage collected form the beach within the collection container 91 which is situated directly behind the rotating screen of the beach cleaner. When the collection container 91 is full, it is hydraulically emptied within a larger collection container (not shown in the figures) located on top of the beach cleaner. Furthermore, the beach cleaner vehicle 100 comprises a flexible tunnel 93. The flexible tunnel 93 is connected to the top 83 of the second separating means 9 such that, when the lighter garbage is blown out at the top 83, it is then guided back into another container 95 through the flexible funnel 93. The current invention can be placed within the larger collection container of the beach cleaner. When the beach cleaner is equipped with the current invention, the small collection container is emptied into the collector of the apparatus.

It will be understood that different implementation variations are possible and within reach of the person skilled in the art, based on the present description.

It should be noted that the above-described embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.