ES2969745T3 - Sorting machine for cleaning incoherent material and corresponding sorting method - Google Patents

Abstract

Sorting machine (10) for cleaning incoherent material, particularly wood-based, and removing inert materials contained in said incoherent material. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Sorting machine for cleaning incoherent material and corresponding sorting method

field of invention

The present invention relates to a sorting machine for cleaning incoherent material, in particular, for removing contaminating materials present therein.

Advantageously, but not restrictively, the contaminating materials in question are of the heavy type, for example, but not only, inert materials such as stones, glass, sand, but also of a metallic or plastic nature.

Contaminating materials are usually primarily associated with incoherent wood-like material, for example, wood filings, wood shavings, shredded wood, wood scraps, or similar or comparable material, which may come from any source.

In particular, in the present invention, cleaning the material by sorting allows fine fractions of incoherent wood material that would otherwise be discarded to be separated and made available.

The present invention also relates to the corresponding selection method for cleaning incoherent material as described above.

Background of the invention

It is known that the reuse of wood material, for example in the form of wood chips, is becoming increasingly important as, where possible, it allows the felling of new trees to be avoided.

In particular, reclaimed wood, from which wood chips, fibers or other forms can be obtained, can be wood from various sources and which, therefore, usually contains a large amount of contaminating materials.

For example, reclaimed wood can come from the processing of wood used to obtain panels or furniture, or furniture in general; recovery of packaging, pallets, containers and crates; of beams, crossbars or planks or construction material in general; post-consumer, in particular, waste treatment and selective collection.

It is quite evident that reclaimed wood can contain pebbles, stones, sand, metals, plastic, etc., which are all foreign components that must be separated from the wood so that it can be reused or recycled. It is also known that wood chips are obtained from fallen trees of various sizes that have in themselves, or are associated with, sand or small stones.

These foreign components or contaminants are typically discharged during chip selection and calibration. In particular, screening machines have been known for some time in the state of the art, designed to separate and select chips and particles based on their granulometry from an incoherent or fibrous mass, whether dry or wet, generally, but not exclusively, of wood-based material.

Screening machines are also known that are configured to remove contaminating materials, inert and not, from this incoherent mass, in order to obtain better quality wood material for further processing.

These machines typically provide sieves with a mesh or disc, or roller sieves with one or more levels, or rows of sorting elements that define a bed onto which the material to be sorted is fed. In a downstream part of the screening process, the pre-sorted wood material may still contain inert material that needs to be removed.

For this purpose, downstream of the screening machines it is necessary to provide one or more incoherent material sorting machines to separate the newly selected wood fraction from the inert fraction still present therein.

In particular, to clean fine fractions of incoherent material, these sorting machines can currently be of the air-operated type and are followed or replaced by wet-type sorting machines in which the separation is based on the variable density of the incoming materials, immersed in a fluid, usually water.

These wet type sorting machines comprise a tank containing water into which the wood material is introduced along with the inert material. Due to the difference in density, the wood material floats while the inert material falls to the bottom of the tank from which it is removed, for example, by means of a chain conveyor device. The same chain conveyor device, in the return segment, touches the water surface, removing the lighter wood material which is recovered and discharged for further treatment.

One of the disadvantages of wet-type sorting machines is that they require a large amount of water at the inlet that must be constantly treated and periodically renewed. This not only implies a significant environmental impact, but also determines high costs for the management and obtaining of water resources. Another disadvantage of wet type sorting machines is that since they are preferably installed outdoors, that is, in an unprotected environment and not subject to controlled temperature regulation, they may be subject to freezing problems that would reduce their productivity and require that numerous plant shutdowns will be carried out. One solution could be to enrich the water with antifreeze products, which, however, could contaminate the wood material and require an additional process to remove them.

Another disadvantage is that water can sometimes act as an adhesive between the fine particles of inert materials and the flakes of wood material which therefore return to the production cycle still contaminated, causing problems that are already known.

Another additional disadvantage may be related to the need, for the purposes of subsequent reuse or recycling of the recovered wood, to eliminate excess moisture contained in the wood that is discharged from the tank.

Therefore, there is a need to perfect a sorting machine for cleaning incoherent material that can overcome at least one of the disadvantages of the state of the art.

In particular, one purpose of the present invention is to provide a sorting machine for cleaning incoherent material that carries out this sorting in a dry environment, that is, without the aid of separating liquids such as water, for example.

Another purpose of the present invention is to provide a sorting machine for cleaning incoherent material that reduces the number of downstream processes and treatment operations in the separated wood material and therefore considerably simplifies the overall structure of the plant where insert.

Another purpose of the present invention is to provide a dry screening method for cleaning incoherent material, that is, without the aid of stripping liquids such as water, for example.

The applicant has devised, tested and materialized the present invention to address the drawbacks of the state of the art and to achieve these and other purposes and advantages.

Document EP 1362643 A1 discloses a sorting machine according to the preamble of claim 1.

Document WO2018/211545 A1 discloses an air-type separation device.

Summary of the invention

The present invention is set forth and characterized in the independent claims. The dependent claims describe other features of the invention or variants of the main inventive idea.

In accordance with the above purposes, a sorting machine for cleaning incoherent material particularly wood-based and for removing inert materials contained in the incoherent material comprises a sorting compartment capable of receiving a flow of incoherent material and in which there is a set roller selection configured to feed the incoherent material in one feeding direction.

The roller selection assembly comprises a plurality of rollers arranged adjacent to each other on a common support plane.

The rollers are arranged in the feeding direction at an increasing distance from each other, defining respective discharge spaces for the passage of incoherent material selected based on the discharge spaces as indicated above, in order to obtain, in the compartment selection as indicated above, at least a first selection area and a second selection area.

The first selection zone and the second selection zone are arranged in sequence in the feeding direction and have different discharge spaces.

The machine as described above comprises at least one collection chamber arranged below the support plane under the second selection area.

The collection chamber is provided with first air introduction means configured to transport a first flow of pressurized air towards the support plane, through the rollers.

The machine as described above also comprises an air-type separation unit, arranged downstream of the roller selection assembly and configured to convey a second flow of pressurized air towards the support plane to intercept incoherent material. at the exit of the roller selection assembly as indicated above.

To this end, according to the invention, the air type separation unit can supply the second air flow which, on the one hand, ensures the separation of the wood material from residual contaminants and, on the other hand, directs the two components , wood material and residual contaminants, to the designated discharge area. This machine makes it possible to eliminate the use of water to separate incoherent wood material and contaminating material, with all the resulting advantages in terms of cost, as well as energy and environmental savings.

Furthermore, separation using only pressurized air and rollers, as described above, completely eliminates the problem related to freezing of water in the winter period, and drying of the wet wood material after it has been separated from the contaminating material.

The first selection zone or the second selection zone, or both, may have selector rollers, advantageously, but not exclusively, which have a conical perimeter shape and are arranged at intervals to define an axial development consisting of a series of opposing grooves. , for example, in the shape of an opposite V. The selector rollers may have, on their perimeter, a profile formed, advantageously, but not exclusively, with a stepped shape and an inclined connecting ramp.

According to the invention and according to the selection level, in the first selection zone, the discharge space between two rollers, substantially defined by the distance between the conical surfaces, advantageously, although not necessarily, measured in a direction orthogonal with respect to the surfaces themselves, has an amplitude that varies in the range between about 0.2 mm and about 3 mm, preferably between about 0.5 mm and about 2 mm.

In this way, sand, stones, small stones, glass, metal, ceramics and other similar and comparable contaminating materials whose size is between approximately 1.2-1.5 mm and approximately 2-2.5 mm are removed.

The first selection zone cooperates with a feeding device that is configured to supply the incoherent material to be selected continuously, or in a periodic or variable manner.

The machine includes, below the support plane, conveying devices that direct the inert materials towards the designated discharge area.

According to the invention and according to the selection level, in the second selection zone, the discharge space between two rollers, substantially defined by the distance between the conical surfaces, advantageously, although not necessarily, measured in a direction orthogonal with respect to the surfaces themselves, has an amplitude that varies in the range between about 3 mm and about 8 mm, preferably between about 4 mm and about 6 mm.

The first selection zone is separated at the bottom from the second selection zone by a separator deflector, configured to direct the inert material to an area below designated for this purpose.

The machine as described above comprises, below the second selection zone, a collection chamber which, advantageously, may have valve means, for example, valve means of the star type, which prevent air from escaping. down.

According to some embodiments, a screening method is provided for cleaning incoherent material, particularly wood-based, and for removing inert materials contained in the incoherent material.

The method includes:

- feeding an incoherent flow of material to the selection compartment;

- carry out in dry conditions, in the selection compartment, a separation according to the size of the incoherent material, as described above, by means of the roller selection assembly that is located on a support plane and along which it is done advance the incoherent material in the feeding direction, including dry separation, depending on size:

a first selection according to size with respect to a first maximum nominal size of the incoherent material and

a second size selection with respect to a second maximum nominal size of the incoherent material, greater than the first maximum nominal size,

wherein, during the second size selection, as described above, at least part of the incoherent material advancing in the feed direction is kept in suspension along the roller selection assembly by means of a first flow of pressurized air passing through the support plane;

- carry out a gravimetric separation by air that allows intercepting incoherent material, at the exit of the roller selection assembly, by means of a second flow of pressurized air, determining a separation by gravity of the incoherent material from the heavy contaminating material that was not removed previously in the separation according to size.

Illustration of the drawings

These and other aspects, features and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the accompanying drawings, in which:

- Figure 1 is a side elevation view of a sorting machine for cleaning incoherent material according to the present invention.

For ease of understanding, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It should be understood that elements and features of one embodiment may conveniently be incorporated into other embodiments without further clarification.

Description of the achievements

Reference will now be made in detail to possible embodiments of the invention, one or more examples of which are shown in the accompanying drawings. Each example is provided by way of illustration of the invention and should not be understood as a limitation thereof.

Before describing these embodiments, it should also be clarified that the present description is not limited in its application to the details of the construction and the arrangement of the components, as described in the following description using the accompanying drawings. The present disclosure may provide other embodiments and may be obtained or implemented in various other ways. It should also be clarified that the phraseology and terminology used in this document are for descriptive purposes only and cannot be considered limiting.

A sorting machine 10 for cleaning incoherent material in the form of chips, in particular wood-based, and for removing inert materials contained in the incoherent material is shown by way of example in Figure 1.

The machine 10 can be placed downstream of a screening machine that has already processed a first selection of the incoherent material based on its granulometry.

In particular, the machine 10, object of the present invention, can be placed downstream of an air-type separation machine from which it can receive incoherent material, having sizes between about 1 mm and about 10 mm, which requires another separation.

The term "incoherent material" here and hereinafter in the description generally refers to loose material of homogeneous or non-homogeneous sizes, preferably, but not necessarily, based on wood and possibly also containing contaminating materials, e.g. although not limited to, inert material such as sand, stones, glass and the like.

The term "chips" herein and hereinafter in the description generally refers to any type of incoherent wood-type material, recycled or untreated, suitable for selection by means of roller sieves, i.e. i.e., for example, wood flakes, wood fragments, forest residues, wood shavings, sawdust, sawmill residues, or the like.

Referring to Figure 1, the machine 10 comprises a selection compartment 31 capable of receiving a flow of incoherent material and in which there is a roller selection assembly 32 configured to feed the incoherent material in a feed direction F.

The roller selection assembly 32 comprises a plurality of rollers 11 arranged adjacent to each other on a common support plane P.

The rollers 11 are arranged in the feed direction F at an increasing distance from each other, defining respective discharge spaces 14, 14' for the passage of incoherent material selected based on the discharge spaces 14, 14', in order to obtain, in the selection compartment 31, at least a first selection zone 12 and a second selection zone 13.

In particular, here and below, discharge space 14, 14' refers to the passage space obtained from the distance between the side surfaces of two adjacent rollers 11.

The first selection zone 12 and the second selection zone 13 are arranged in sequence in the feeding direction F and have different discharge spaces 14, 14'.

The second selection zone 13 is located downstream of the first selection zone 12 with respect to the feed direction F.

The rollers 11 are configured to rotate around their own axis of rotation.

The axes of rotation of the rollers 11 are parallel to each other and coplanar. In this way, the support plane P is substantially horizontal.

According to some embodiments, the rollers 11 may be of a known type.

For example, the rollers 11 may advantageously, but not exclusively, have a perimeter shape to define, when arranged at intervals, an axial development consisting of a series of opposing grooves, for example, in the shape of an opposing V.

The rollers 11 rotate in the same direction and are arranged adjacent to each other to define a progressive succession of discharge spaces 14, 14' having respective amplitudes G1, G2 of the desired and adjustable value.

According to some embodiments, the first amplitude G1 may be different from the second amplitude G2.

According to some embodiments, the different amplitudes G1, G2 may also be variable within the same selection zone 12, 13, for example, increasing in the feed direction F of the material to be selected. According to some embodiments, the first selection zone 12 may have rollers 11 that define between them discharge spaces 14 that have a first amplitude G1, and the second selection zone 13 may have rollers 11 that define between them discharge spaces 14' that they have a second amplitude G2 greater than the first amplitude G1. According to some embodiments, the amplitude G1, G2 of the discharge spaces 14 can be selectively adjusted. In this way, it is possible to establish the desired degree of cleaning of the incoherent material, that is, it is possible to define the size range of the inert material to be removed.

According to some embodiments, the first amplitude G1 may be variable between about 0.2 mm and about 3 mm, preferably between about 0.5 mm and about 2 mm.

According to some embodiments, the second amplitude G2 can be variable between about 3 mm and about 8 mm, preferably between about 4 mm and about 6 mm.

In this way, contaminating materials such as inert materials such as sand, stones, small stones, glass, metal, ceramics and other similar and comparable contaminating materials whose size is between about 1.2 mm and about 2 mm are removed in correspondence with the first selection zone 12, falling by gravity between the discharge spaces 14 defined by the rollers 11 of the first selection zone 12.

To this end, the machine 10 comprises a collection compartment 35 arranged below the support plane P under the first selection zone 12 and through which the heavy contaminating material, removed in the first selection zone 12, can fall by gravity.

According to possible embodiments, nozzles may be installed in the collection compartment 35 to supply a pressurized air flow directed towards the support plane P and configured to facilitate the separation of the lighter incoherent wood material from the heavier contaminating material.

In relation to the reasonable conformation of the incoherent material to be selected, that is, whether or not a sandy component is present therein, the first selection zone 12, or one or more intermediate selection zones, if present, does not They can be affected by air flows, for example, to allow the sandy component to also be removed by gravity as described above.

According to some embodiments, the machine 10 comprises a feeding device 24, placed above the support plane P in communication with the selection compartment 31 in correspondence with the first selection area 12.

The feeding device 24 is configured to feed the incoherent material to the selection compartment 31, on the roller selection assembly 32.

The feeding device 24 may comprise valve means 29, for example, star-type valve means 29, which prevent air from leaving the machine 10 while feeding the incoherent material.

The valve means 29 allow the incoherent material to be introduced continuously or periodically, that is, variable. According to some embodiments, the machine 10 comprises, below the support plane P, conveying devices that direct the inert material towards the designated discharge area.

For example, in correspondence with the discharge area as indicated above, the machine 10 may provide extraction devices to evacuate inert material that is continuously discarded, or container devices 33 that can be emptied periodically.

According to some embodiments, the first selection zone 12 is separated from the second selection zone 13. In particular, between the first selection zone 12 and the second selection zone 13 there is a separator deflector 15, arranged below the support plane P , configured to keep the incoherent material passing through the discharge spaces 14 of the first selection zone 12 separate from the incoherent material passing through the discharge spaces 14' of the second selection zone 13.

To this end, the spacer deflector 15 is inclined with respect to the support plane P.

According to a variant, the separator deflector 15 can also have a vertical or sub-vertical positioning.

Advantageously, in Figure 1, the separator deflector 15 is substantially vertical or subvertical, since it is orthogonal or almost orthogonal to the support plane P.

The separator deflector 15 is partially inserted between the last roller 11 of the first selection zone 12 and the first roller 11 of the second selection zone 13 without interfering with the movement of the rollers 11.

According to some embodiments, the separator deflector 15 may be fixed or selectively movable in a direction parallel to the feed direction F.

According to some embodiments, the machine 10 comprises at least one collection chamber 16 arranged below the support plane P under the second selection area 13.

The collection chamber 16 can advantageously, but not necessarily, have valve means 17, for example, star-type valve means 17, which prevent air from escaping downwards, but allow evacuation of inert material that has fallen. through 14' discharge spaces.

The collection chamber 16 is delimited laterally on one side by the separating deflector 15 and on the other by an inclined wall 30.

The inclined wall 30 delimits the roller selection assembly 32 at the downstream bottom.

The collection chamber 16 is delimited at the bottom by the valve means 17 and is open upwards. The chamber 16 faces directly, upwardly, the rollers 11 of the second selection zone 13 and the discharge spaces 14' defined between them.

The collection chamber 16 is provided with first air introduction means 25 configured to transport a first pressurized air flow A1 towards the support plane P, through the rollers 11.

The first air flow A1 keeps in suspension the lighter incoherent material that continues to advance, while the heavy contaminants fall through the discharge spaces 14' towards the collection chamber 16, from which they are evacuated through the means valve 17.

In this way, inert materials such as sand, stones, small stones, glass, metal, ceramics and other similar and comparable contaminating materials whose size is less than about 4-6 mm are removed in correspondence with the second selection zone 13, falling by gravity between the discharge spaces 14' defined by the rollers 11 of the second selection zone 13.

According to some embodiments, the machine 10 comprises an air-type separation unit 18, arranged downstream of the roller selection assembly 32 and configured to convey a second pressurized air flow A2 towards the support plane P to intercept the material. incoherent at the outlet of the roller selection assembly 32. The air-type separation unit can be placed downstream of the last of the at least two selection zones 12, 13, that is, downstream of the support plane P.

The second air flow A2 allows the incoherent wood material arriving from the roller selection assembly 32 to be separated from heavy residual contaminants that have not been previously removed.

The air type separation unit 18 comprises one or more blowing devices 19 configured to convey the second air flow A2 towards the incoherent material at the outlet of the roller selection assembly 32, in correspondence with a terminal edge 21 defined by the last roller 11 of the roller selection assembly 32.

The one or more blowing devices 19 are configured to convey the second air flow A2 with an angle of inclination a with respect to the support plane P of between approximately 20° and approximately 60°, advantageously approximately 45°.

The incoherent material pushed by the second air flow A2 follows a substantially curved path, for example parabolic, with a range depending on the weight of the material, as described above.

In this way, the incoherent wood material follows a longer path than the heavy polluting material that substantially falls into the designated discharge zone just below the terminal edge 21.

According to some embodiments, the air-type separation unit 18 also comprises a separator deflector 20 positioned in correspondence with the discharge zone downstream of the roller selection assembly 32. The separator deflector 20 divides the discharge zone into a zone of discharge 23 for contaminants and a discharge zone 22 for wood material.

The discharge zone 22 for wood material is further away, with respect to the discharge zone 23 for pollutants, from the support plane P, in a direction parallel to the feed direction F.

For example, in correspondence with the discharge area 22 for wood material, as described above, the machine 10 may provide extraction devices to evacuate the discarded inert material continuously, or container devices 34 that can be emptied periodically.

The discharge zone 23 for contaminants may, for example, flow into the container device 33 which collects, without separation, all of the separated contaminant material.

According to some embodiments, the separator deflector 20 may be movable to adjust its position in a direction parallel to the feed direction F.

In this way, it is possible to define, on each occasion and in relation to the weight of the incoherent material to be cleaned, the size of the discharge zone 23 for contaminants and of the discharge zone 22 for wood material. According to some embodiments, the machine 10 comprises air compression devices 26, 27 respectively configured to compress the air to be transported to the air introduction means 25 and to the blowing devices 19 of the air type separation unit. 18.

According to possible embodiments, the same air compression device 26, 27 processes the air flows A1, A2 both for the air introduction means 25 and also for the blowing devices 19.

However, advantageously, it is preferable to have two distinct and separate air compression devices 26, 27 that supply air flows A1, A2 characterized by different compression coefficients or by different flow rates.

According to possible embodiments, the air compression devices 26, 27 can be chosen from a group comprising a compressor or a fan, depending on the required compression coefficient.

According to some embodiments, the machine 10 may provide an air inlet chimney 28 necessary to evacuate the air flows A1, A2 and to maintain the pressure within the machine 10 in balance.

For this purpose, the air inlet chimney 28 can be of the "suction" type, that is, with depression. This allows the air flows A1, A2 to be transported at the outlet of the air introduction means 25 and the blowing devices 19 towards the air inlet chimney 28, increasing its speed.

According to possible embodiments, the air inlet chimney 28 can be connected to the suction mouth of the air compression devices 26, 27.

According to some embodiments, a screening method is provided for cleaning incoherent material, particularly wood-based, and for removing inert materials contained in said incoherent material.

The method includes:

- feeding an incoherent flow of material to the selection compartment 31,

- carry out in dry conditions, in the selection compartment 31, a separation according to the size of the incoherent material, by means of the roller selection assembly 32 which is located on a support plane P and along which the material is advanced incoherent in the feed direction F, including dry separation, depending on size:

a first selection according to size with respect to a first maximum nominal size of the incoherent material and

a second size selection with respect to a second maximum nominal size of the incoherent material, greater than the first maximum nominal size,

wherein, during the second size selection, as described above, at least part of the incoherent material advancing in the feed direction F is kept in suspension along the roller selection assembly 32 by means of a first pressurized air flow A1 passing through the support plane P,

- carry out a gravimetric separation by air that allows intercepting incoherent material, at the exit of the roller selection assembly 32, by means of a second pressurized air flow A2, determining a separation by gravity of the incoherent material from the heavy contaminating material that does not was previously eliminated in the separation according to size.

With particular reference to the machine 10 shown in Figure 1, the feeding of the flow of incoherent material is carried out by the feeding device 24 which, thanks to the valve means 29, allows the regulation of the incoherent material within the selection compartment 31 .

The first separation according to size occurs in correspondence with the first selection zone 12, in which the distance between the rollers 11 defines discharge spaces 14 that have an amplitude G1 directly correlated with the first maximum nominal size of the incoherent material to be will delete.

The second separation according to size occurs in correspondence with the second selection zone 13, in which the distance between the rollers 11 defines discharge spaces 14' that have an amplitude G2, greater than the amplitude G1, directly correlated with the second maximum nominal size of incoherent material to be removed.

In correspondence with the second selection zone 13, the air introduction means 25 supply the first pressurized air flow A1 through the support plane P, keeping in suspension part of the incoherent material that advances in the feed direction F.

Subsequently, the blowing devices 19 supply the second air flow A2 which hits the incoherent material at the outlet of the roller selection assembly 32, projecting the incoherent wood material further, in a direction parallel to the feed direction F, with respect to the heavy contaminating material that falls immediately after the terminal edge 21.

It is also clear that, although the present invention has been described with reference to some specific examples, one skilled in the art will undoubtedly be able to achieve many other equivalent forms of an incoherent material sorting machine and the corresponding sorting method, which have the characteristics set forth in the claims and, therefore, fall within the field of protection defined therein.

In the following claims, the sole purpose of parenthetical references is to facilitate reading: restrictive factors should not be considered with respect to the field of protection claimed in the specific claims.

Claims (10)

1. Sorting machine for cleaning incoherent material particularly wood-based and for removing inert materials contained in said incoherent material, comprising - a selection compartment (31) capable of receiving a flow of incoherent material and in which there is a roller selection assembly (32) configured to feed said incoherent material in a feeding direction (F) and comprising a plurality of rollers (11) arranged adjacent to each other on a common support plane (P) and arranged in said feeding direction (F) at an increasing distance from each other in said feeding direction (F) defining the respective discharge spaces (14 , 14') for the passage of incoherent material selected based on said discharge spaces (14, 14'), in order to obtain, in said selection compartment (31), at least a first selection area (12) and a second selection zone (13) in sequence in said feeding direction (F) and having different discharge spaces (14, 14'), - at least one collection chamber (16) arranged below said plane of support (P) under said second selection area (13) and the machine being further characterized in that: - said at least one collection chamber is provided with first air introduction means (25) configured to transport a first flow of air (A1) under pressure towards said support plane (P), through said rollers (11) , - an air type separation unit (18), arranged downstream of said roller selection assembly (32) and configured to transport a second pressurized air flow (A2) towards said support plane (P) to intercept incoherent material at the exit of said roller selection assembly (32). 2. Machine according to claim 1, characterized in that the discharge spaces (14) of said first selection zone (12) have a first amplitude (G1) in said feeding direction (F), and the discharge spaces (14 ') of said second selection zone (13) have a second amplitude (G2, in said feeding direction (F), greater than said first amplitude (G1). 3. Machine according to claim 2, characterized in that said first amplitude (G1) is between approximately 0.2 mm and approximately 3 mm, preferably between approximately 0.5 mm and approximately 2 mm, and that said second amplitude ( G2) is between about 3 mm and about 8 mm, preferably between about 4 mm and about 6 mm. 4. Machine as in any preceding claim herein, characterized in that a separating deflector (15) is provided between said first selection zone (12) and said second selection zone (13), arranged below said support plane (P) and configured to keep the incoherent material passing through the discharge spaces (14) of the first selection zone (12) separate from the incoherent material passing through the discharge spaces (14') of the second selection area (13). 5. Machine as in any preceding claim herein, characterized in that said air-type separation unit (18) comprises one or more blowing devices (19) configured to transport said second air flow (A2) towards the incoherent material coming out of said roller selection assembly (32), in correspondence with a terminal edge (21) defined by the last roller (11) of said roller selection assembly (32). 6. Machine according to claim 5, characterized in that said one or more blowing devices (19) are configured to transport said second air flow (A2) with an angle of inclination (a) with respect to said support plane (P ) of between approximately 20° and approximately 60°. 7. Machine as in any preceding claim herein, characterized in that said air-type separation unit (18) comprises a separator deflector (20), positioned in correspondence with a discharge zone downstream of said selection assembly. of rollers (32), which divides said discharge zone into a discharge zone (23) for contaminants and a discharge zone (22) for wood material, said discharge zone (22) for wood material being further away, with respect to said discharge zone (23) for contaminants, of said support plane (P), in a direction parallel to said feed direction (F). 8. Machine according to claim 7, characterized in that said separator deflector (20) is movable to adjust its position in a direction parallel to said feeding direction (F). 9. Machine as in any previous claim herein, characterized in that it comprises an air inlet chimney (28) configured to discharge said air flows (A1, A2) and to maintain the pressure inside the machine in balance. 10. Selection method for cleaning incoherent material, particularly wood-based, and for removing inert materials contained in said incoherent material, said method comprising: - feeding a flow of incoherent material to a selection compartment (31), - carry out in dry conditions, in said selection compartment (31), a separation according to the size of said incoherent material by means of a roller selection assembly (32) that is located on a support plane (P) and along from which said incoherent material is advanced in a feeding direction (F), comprising dry separation, depending on the size: a first selection according to size with respect to a first maximum nominal size of said incoherent material and a second selection according to size with respect to a second maximum nominal size of said incoherent material, greater than said first maximum nominal size, said method being characterized by: - maintaining, during said second selection according to size, at least part of said incoherent material advancing in the feed direction (F) in suspension along said roller selection assembly (32) by means of a first air flow (A1) under pressure that passes through the support plane (P), - perform a gravimetric separation by air that allows intercepting incoherent material, at the exit of said roller selection assembly (32), by means of a second flow of air (A2) under pressure, determining a separation by gravity of the incoherent material of heavy contaminating material that was not previously eliminated in said separation according to size.