WO2018207223A1

WO2018207223A1 - Mobile roller screener for granular mined material

Info

Publication number: WO2018207223A1
Application number: PCT/IT2018/050082
Authority: WO
Inventors: Bruno Mognon; Adel SAOUDI; Angiolino BROTTO
Original assignee: Superstar Sas Di Mognon Bruno & C
Current assignee: Superstar Sas Di Mognon Bruno & C
Priority date: 2017-05-12
Filing date: 2018-05-11
Publication date: 2018-11-15
Anticipated expiration: 2019-11-12
Also published as: IT201700051710A1

Abstract

The present invention relates to the mining industry. More specifically, it relates to a mobile roller screener (1 ) for granular mined material comprising at least one first series of rollers (10), comprising a plurality of rollers (2) arranged parallel to one another on a same plane (ττ), each having a main axis of rotation (x), and motor means (13) adapted to rotate said rollers (2) in a coordinated manner around their axis (x). Each roller (2) is provided with a plurality of shaped discs (3) mounted at regularly-spaced intervals, and said rollers (2) are separated from one another so that the space left between the shaped discs (3) acts as a discriminating factor for screening said granular mined material. Said roller screener (1 ) comprises means of movement adapted to allow it to move around the working area.

Description

MOBILE ROLLER SCREENER FOR GRANULAR MINED MATERIAL

Field of application

The present invention relates to the mining industry.

More specifically, it relates to a mobile roller screener for granular mined material, for use for example on sites for the extraction of phosphate, limestone, coke, coal, salt, gypsum, bauxite, quartz, granite, etc...

Prior art

Screening, or the separation according to size, of mined materials, is one of the pre-treatment operations to which extracted materials are subjected before leaving the quarry and being sent to various destinations and for various uses.

Currently, at a quarry, a space is set aside where specific screeners are positioned, and to where the trucks (or in technical jargon dumpers) come loaded with mined material.

Currently, granular mined materials extracted are loaded by a vehicle, usually provided with a shovel, into the tipping body of a dumper near the extraction site, without making any distinction or preselection of the material: all extracted material, regardless of its size, is loaded onto the dumpers destined for the screening station. The capacity of the dumper body can vary from around 50 to 300 tons, while the capacity of the loading shovel varies from 5 to 35 tons. Several shovel-loads are therefore needed to fill the entire dumper body, before the dumper can leave the extraction site and make its way to the screening site. On arrival at the screening site, the dumper unloads the material contained in the body into a hopper that directly feeds the screener, which is usually of the roller type.

A traditional roller screener is formed of several parallel axes rotating in a coordinated manner, positioned horizontally on a same plane. Mounted on the axes, at regularly-spaced intervals, are discs of various shapes (oval, hexagonal, lobed, etc.), which form a sort of grille. The distance between the various rotating axes, and the space left between the discs on the same axis, act as discriminating factors for screening the materials: those materials of a larger size are driven by the rotation of the discs along the screening plane towards an unloading point, while finer materials pass through the screener and fall onto a special conveyor belt below for collecting and transporting the material.

In brief, the mining extraction process consists of the following operations:

- loading extracted material onto the dumpers;

- transporting the material from the extraction point to the processing center where the roller screeners are located;

- introducing the material into the hopper for loading the screeners;

- selecting the material by means of the screeners;

- collecting the material produced on specific conveyer belts and transporting it to the next processing phases;

- expelling material of a large size (or grinding with another cycle); - loading, transporting and unloading the large-size material in specific quarry filling areas.

The above-described procedure for selecting mining material based on the different grit sizes is today very long and complex, as well as economically expensive.

The phases of loading the mining material to be sorted from the extraction site into the dumper body, transporting the material from the extraction site to the screening site, and the subsequent phase of unloading the material from the dumper body into the hopper for feeding the screener, require a great deal of time and considerable energy use for the operation of all the vehicles and machinery involved.

Furthermore, transfers around quarries and mining sites in general are not very easy: roads are tortuous and uneven, and it is not always easy for heavy dumpers and loads of material to move from one site to another.

Even more disadvantageously, when it exits the screener, the screened material is transported by a conveyor belt and thus will need to be removed, or once again loaded into a dumper body to be moved again and brought to the next processing phases, or in any case away from the quarry.

It is clear that all these operations of loading, unloading and transportation can hold up productivity and lead to significant consumption of energy and fuel.

Description of the invention An object of the present invention is to eliminate the drawbacks mentioned above, and thereby to optimize the production process, i.e. the extraction and sorting of mining material based on the grit sizes, reducing processing times and operational energy consumption, and increasing productivity.

It is therefore an object of the present invention to conduct all screening operations in the proximity of the extraction area, by following the movement of the extraction face with the screener, leaving large size material directly in the extraction area, and thus loading onto the dumper trucks and transporting only useful material.

A further object is to provide a screener for mining material that is sturdy, efficient and versatile.

These objects are achieved by a mobile roller screener for granular mined material comprising at least one first series of rollers, comprising a plurality of rollers arranged parallel to one another on a same plane, each having a main axis of rotation, and motor means adapted to rotate said rollers in a coordinated manner around their axis, each roller being provided with a plurality of shaped discs mounted at regularly-spaced intervals, where said rollers are separated from one another so that the space left between the shaped discs acts as a discriminating factor for screening said granular mined material,

characterized in that said roller screener comprises means of movement adapted to allow it to move around the working area.

In particular, said means of movement comprise a plurality of motorized, steered wheel assemblies, provided with rubber tired wheels. Advantageously, said wheels are motorized by means of a reduction gear and motor, either hydraulic or electric.

Alternatively, said plurality of wheels may be replaced by at least one pair of caterpillar tracks.

According to a further aspect of the invention, said roller screener comprises a portal-like space structure, comprising a plurality of uprights and cross members adapted to support above ground said at least one first series of rollers.

In a preferred variant, said portal-like space structure comprises means for adjusting the length of said uprights to change the working height of said at least one first series of rollers.

In particular, said uprights comprise a first and a second portion slidingly associated with one another, and said means for adjusting the length of said uprights comprise lifting cylinders, adapted to act between said first and second portion of said uprights.

Alternatively or additionally, said means for adjusting the length of said uprights comprise extendable articulated shock absorbers connecting said means of movement and said uprights.

According to a further aspect of the invention, said portal-like space structure comprises translation means for said at least one first series of rollers, adapted to allow the movement of said at least one first series of rollers in the plane containing them, in a direction transversal to the main axis of rotation of the rollers.

In particular, said translation means comprise:

- an overhead crane structure provided with wheels associated with said at least one first series of rollers;

- rails associated with said portal-like space structure on which said overhead crane structure can slide by means of said wheels;

- at least one hydraulic piston placed between said portal-like structure and said overhead crane structure, adapted to control the translation of said overhead crane structure and the consequent movement of said at least one first series of rollers.

Furthermore, said mobile roller screener comprises a loading tray for said granular mined material.

Advantageously, said loading tray is rotatingly associated with said overhead crane structure by means of a horizontal-axis hinged joint parallel to the longitudinal axes of said rollers, so as to be able to take up a position for loading said granular mined material underneath the plane of said rollers and a position for tipping the material above said at least one first series of rollers.

In particular, said roller screener comprises at least one hydraulic piston placed between said portal-like structure and said loading tray, adapted to control the movement of said loading tray around said horizontal-axis hinged joint.

Furthermore, said loading tray comprises a mobile bulkhead, adapted to regulate the downward flow of said granular mined material from said loading tray onto said at least one first series of rollers.

According to possible variant embodiments of the invention, said mobile roller screener further comprises:

- an unloading slide for the granular mined material held and advanced above said rollers;

- protective bulkheads placed next to said at least one first series of rollers in a direction transversal to the longitudinal axis of the rollers. In a preferred variant, the containment plane of the longitudinal axis of said rollers is inclined with respect to a horizontal plane.

In an even more preferred variant, the roller screener comprises a second series of rollers, mounted specularly with respect to said first series.

The invention presents numerous advantages.

The innovative idea consists of making available a mobile screener capable of performing the screening and loading operations simultaneously directly at the various points of extraction, without having to install loading belts or hoppers for containing the mineral.

The main advantage relates to mobility: thanks to the means of movement, the screener can move around the quarry to follow the mined material extraction activities, moving to the various extraction sites and following the natural spatial changes to the extraction face. Screening of the mined material can therefore take place directly at the point of extraction without having to use dumpers to move the extracted material from one area of the quarry to another. The shovel for loading the material, instead of filling the dumper body, unloads the granular material directly onto the screener or into the screener loading tray.

The rubber tired wheels allow the screener to travel on asphalt, cement, uneven roads and slopes.

The steered wheels enable the wheel assemblies to turn even thru 270° thereby further facilitating movement of the screener.

A further important advantage comes from the elevated position of the screener: the portal-like space structure supports the screener and allows it to work directly above the body of a dumper, so that the sorted material passing through the rollers falls directly into a collection container and no longer needs to be carried away on conveyor belts and then loaded into the dumpers.

Alternatively, the screened material can be deposited directly on the ground, creating a linear accumulation as the screener advances, which may even be of a considerable height.

Even more advantageously, the portal structure that elevates the screener makes it possible to load the dumpers directly at the extraction site only with material that has already been screened, thereby reducing the volume to be transported, by limiting it to useable material only.

Furthermore, thanks to the combination of the means of movement and the portal structure, the screener enables continuous dumper loading and their optimal filling by means of the longitudinal movement of the entire screening system above the dumper.

To this end, the translation means for the entire series of rollers are also advantageous: thanks to the overhead crane structure, to which the rollers are fixed, sliding on specific rails on the portal structure, the screener can also slide in a direction transversal to the axis of the dumper and the rollers, uniformly filling the body even laterally, up to the edge of the sides.

The possibility of adjusting the height of said portal-like space structure, in addition to making the screener extremely versatile by enabling it to be positioned at different heights depending on the heights and dimensions of the various dumpers above which it is positioned, also makes it easier to move the screener around the quarry: during movements, it is in fact possible to lower the portal-like space structure, reducing its size and lowering its center of gravity, thereby avoiding the risk of unbalancing and tipping over, especially when moving along sloping roads.

The loading tray, which can tip around its horizontal-axis hinge, allows the shovel for loading the mined material not to have to unload above the screener. Although the shovel can come close to the portallike space structure, there is nevertheless always a certain area which the shovel cannot enter, for example due to the projection of the wheels or the size of the dumper. The possibility of loading the loading tray at a height lower than the plan of the screener rollers, enables the shovel to remain at a safe distance from the portal structure.

The loading tray also makes it possible to store a volume of mineral corresponding to various shovel-loads and to feed the screener at working intervals and with volumes that differ from those of the shovel. It is therefore also possible to use small shovels that are easier to move and require less energy consumption.

Said unloading slide for the mined material held by the rollers (material of a larger size than the screening measurement), favors disposal of the material, by directing it towards a specific falling point.

Even more advantageously, the axes of the rollers lie on an inclined plane that facilitates the advancement of material along the screener and towards said unloading slide.

The protective bulkheads placed to the sides of the screener rollers prevent material from accidentally falling under the screener, so as to reduce the risk of crushing either the equipment below or the operators moving near the screener.

In general, the invention advantageously reduces the costs of handling and processing the mined material, by resulting in the need, for example, for a smaller number of transport vehicles, and thereby reducing all expenses related to the initial outlay (dumpers and large shovels), their operation (drivers, fuel, etc..) and maintenance costs (tires, grease, shock absorbers, parts, etc.).

Furthermore, the invention enables productive capacity to be increased, given the increased loading speed of the screener, the possibility of placing several screeners side by side above the dumper body, and the direct passage of the sorted material from the screener to the transport dumper to the subsequent processing phases, without further passages on conveyor belts.

In substance, the number of dumpers used is significantly reduced while hourly production remains the same, or alternatively, if the number of dumpers used remains the same, a greater quantity of workable material is produced.

Brief description of the drawings

Further characteristics and advantages of the invention will be more apparent from the following description of a preferred embodiment, illustrated by way of non-limiting example, and with the aid of the figures, wherein:

Fig. 1 shows a schematic axonometric view of a mobile roller screener for granular mined material according to a simplified variant of the invention;

Fig. 2 shows an axonometric view of a mobile roller screener for granular mined material according to a first variant of the invention; Figs. 3A and 3B show a front plan view of the mobile screener shown in Fig. 2, in two different working phases; Fig. 4 shows an overhead plan view of the mobile screener shown in Fig. 2;

Fig. 5 shows a side plan view of the mobile screener in the working phase shown in Fig. 3B;

Fig. 6 shows a transversal cross-section along a vertical plane, of a part of the screener according to the invention;

Fig. 7 shows an axonometric view of a mobile roller screener for granular mined material according to a second variant of the invention;

Figs. 8A and 8B show a side plan view of the mobile screener in a simplified form, in two different configurations of the length of the uprights;

Figs. 9A and 9B show a side plan view of the mobile screener in a simplified form, in two different configurations of the extension of the articulated shock absorbers;

Figs. 10A, 10B, 10C, 10D show, in a front plan view with partial transparency of the dumper body, the mobile screener shown in Fig. 2, in four different working phases;

Figs. 1 1 A, 1 1 B, 1 1 C, 1 1 D show, in a front plan view with partial transparency of the dumper body, the mobile screener shown in Fig. 7, in four different working phases.

Detailed description of an example of a preferred embodiment

With particular reference to the Figures, there is shown a mobile roller screener 1 for granular mined material for use in open cast quarries and mines.

Said screener 1 , having a main axis of development y, essentially comprises: - a first 10 and a second 20 series of rollers, each comprising a plurality of rollers 2 with a longitudinal axis x, placed side by side;

- a supporting portal-like space structure 5 for said first 10 and said second 20 series of rollers;

- means of moving said screener 1 in the working area.

In all the variants shown, said means of movement comprise four wheel assemblies 40.

Said wheel assemblies 40 each comprise two twinned rubber-tired wheels 4, rotatingly supported by wheel reduction gears, each connected to its own hydraulic or electric motor, by means of an angular reduction gear.

The dimensions and type of tires on said wheels 4 will be chosen according to the conditions of the ground on which the screener 1 has to move, and its weight.

Said wheel assemblies 40 are steered, and can rotate thru around 270°.

A steel mesh net 18 is placed around each individual wheel assembly 40 to protect the tires from possible damage caused by an accidental impact with the mined material.

Alternatively, said means of movement could be a caterpillar-track type.

Said series of rollers 10, 20 are placed specularly so that the longitudinal axis x of their rollers 2 is transversal to the main axis of development y of said screener 1 .

The rollers 2 of each series 10, 20 are mounted parallel to one another on the same plane π and can rotate in a coordinated manner around their longitudinal axis x. The coordinated rotation of the rollers 2 favours the advancement of the mined material during the screening operation.

Each roller 2 is provided with a plurality of shaped discs 3 welded to it, with for example an elliptical shape, placed at regularly-spaced intervals.

Said rollers 2 are spaced from one another to create a grille of full and empty spaces, so that the space left between the rollers 2 and the shaped discs 3 of adjacent rollers acts as a discriminating factor for screening said granular mined material.

Each roller 2 is fitted with its own hydraulic motor 13, or alternatively an electric motor, and with a specific reduction gear to reduce the rotation speed to 50/60 rpm.

Said portal-like space structure 5 is made of steel tubular elements with a square or rectangular cross section, and is composed of uprights 15 and cross members 16, resting on the ground on the wheel assemblies 40, connected to one another by support members 17 of said portal-like space structure 5.

Arranged on the top of said portal-like space structure 5 are the two series of rollers 10, 20 side by side, while below the structure, and therefore also below the rollers 2, is the body C of the dumper ready to be filled with the sorted material.

The dumper is placed underneath the portal structure 5 so that the main axis of development z of its body C is transversal to the main axis of development y of said screener 1 and is parallel to the individual longitudinal axes x of the rollers 2.

The containment plane π of the longitudinal axis x of said rollers 2 is inclined with respect to a horizontal plane. The angle of inclination a is around 5°, and is adapted to favour the advancement of the material along the screener 1 .

Said portal-like space structure 5 comprises translation means for said series of rollers 10, 20 side by side, adapted to allow the movement of said rollers in their containment plane ττ, in a direction transversal to their main axis of rotation x.

With particular reference to the axonometric Figures 2 and 7, and to the side views shown in Figures 3A and 3B where this movement in a direction transversal to the axis of rotation x of said rollers is evident, said translation means comprise:

- an overhead crane structure 1 1 provided with support wheels 14 for said series of rollers 10, 20;

- two rails 21 associated with said portal-like space structure 5 on which said overhead crane structure 1 1 can slide by means of said wheels 14;

- two hydraulic pistons 22 placed between said portal-like structure 5 and said overhead crane structure 1 1 , to the sides of said two series of rollers 10, 20, adapted to control the translation of said overhead crane structure 1 1 and the consequent movement of said series of rollers 10, 20.

Said portal-like space structure 5 comprises means for adjusting the length of said uprights 15 to change the working height of said series of rollers 10, 20, with respect to the plane of the ground.

With particular reference to the simplified variant shown in Figure 1 , to Figure 5, and to Figures 8A and 8B, the uprights 15 of said portal-like space structure 5 are telescopic and comprise a first 15' and a second 15" portion slidingly associated with one another. Said means for adjusting the length of said uprights 15 comprise lifting cylinders 23 connected to a hydraulic drive system. Said lifting cylinders 23 are adapted to act between said first 15' and said second 15" portion of said uprights 15.

With particular reference to the variants shown in Figures 2 and 7 and to Figures 9A and 9B, said means for adjusting the length of said uprights 15 comprise extendable articulated shock absorbers 24 arranged between the wheel assemblies 40 and said uprights 15.

As can be seen from a graphic comparison of Figures 8A, 8B and 9A, 9B, the vertical extension of the uprights 15 obtained with the lifting cylinders 23 and the telescopic structure 15', 15" of the uprights, is greater than the vertical extension obtained using the extendable articulated shock absorbers 24. Nevertheless, a combination of both technologies is possible, in order to increase the lifting/lowering capacity of the working plane of said series of rollers 10, 20.

Advantageously, it is also possible to increase or decrease the extension of the uprights 15 individually and independently. For example, by increasing or decreasing the extension of a pair of uprights 15 aligned along the axis x of the rollers 2, it is possible to increase the angle of inclination a of the plane π containing the rollers, so as to facilitate sliding of the granular material during screening operations.

Furthermore, the possibility of managing the extension of the uprights 15 individually allows the screener 1 to adapt better to unevenness in the ground.

Said mobile screener 1 further comprises:

- a loading tray 6 for said granular mined material to be screened; - an unloading slide 9 for the granular mined material of a large size, held and advanced above said rollers 2.

Said loading tray 6 is rotatingly associated with said overhead crane structure 1 1 , by means of a horizontal-axis hinged joint 7 parallel to the longitudinal axes x of said rollers 2.

Alternatively, in a simplified variant of the mobile screener 1 , without said overhead crane structure 1 1 supporting said series of rollers 10, 20, said loading tray 6 will be rotatingly associated directly with said portal structure 5.

Said screener 1 also comprises a pair of hydraulic pistons 8 adapted to control the movement of said loading tray 6 around said horizontal-axis hinge 7.

The ends of said hydraulic pistons 8', 8" are hinged to the overhead crane structure 1 1 supporting said series of rollers 10, 20 and to the sides of said loading tray 6 respectively.

Said loading tray 6 is therefore tippable, provided with a rotation movement around its horizontal-axis hinge 7.

In general, said loading tray 6 is therefore able to take up a lower rest position, underneath the plane π of said rollers 2, when loading said granular mined material (Figure 3A), or a higher unloading position, placed above the plane π of said rollers 2, when tipping the material onto the rollers (Figure 3B).

To avoid possible overturning of the overhead crane structure 1 1 during rotation of the loading tray 6 to tip the material from the loading tray 6 onto the rollers 2, said overhead crane structure 1 1 comprises anti-tipping rollers placed underneath said rails 21 on which it slides.

Said loading tray 6 may have a different shape depending on the vehicle which will load it.

In the event of using a loading vehicle P provided with a traditional shovel, especially if small in size (Figures 2 and 10), the loading tray 6 needs to be lowered as much as possible to adapt to the height reached by the shovel and so as not to oblige the vehicle to get dangerously close to the portal structure of the screener. The loading tray 6 must therefore have an elongated shape that allows it to go close to the ground.

In the case where loading is done with a loading vehicle S provided with a long-arm claw, the material can be unloaded at a higher height and therefore the tray can be smaller and with a shorter radius of rotation (Figures 7, 1 1 ).

Said loading tray 6 comprises a mobile bulkhead 12 adapted to limit and regulate the fall of material onto the series of rollers 10, 20.

The unloading slide 9 for the granular mined material held above said rollers 2 is also rotatingly associated with said portal structure 5 (Figure 10A), so as to be able to take up an extended overhanging position during the screening phase in order to favour unloading of the material, and a closed, lowered position along the portal structure 5 when moving the mobile screener 1 from one area of the quarry to another.

With particular reference to the cross-section shown in Figure 6, said screener 1 comprises protective bulkheads 19 placed next to said series of rollers 10, 20 in a direction transversal to the longitudinal axes x of the rollers. In addition to containing the material laterally, they prevent the material from accidentally falling under the screener 1 outside the working area, and they protect the reduction gears of the individual rollers 2 from falling dust and detritus.

All electrical equipment mounted on said screener 1 is powered by motor and current generator means 25 associated with the portal structure 5 according to known art.

With particular reference to the series of Figures 10A, 10B, 10C, 10D and 1 1 A, 1 1 B, 1 1 C, 1 1 D, these show the working phases of the mobile screener 1 according to two variants of the invention, which differ from one another only for the loading vehicle P, S that can be used, and thus for the shape of the loading tray 6 provided on the screener.

In Figures 10A, 1 1 A, the mobile screener 1 is placed straddling the dumper C to be loaded; the loading tray 6 is in a fully lowered position, while the overhead crane structure 1 1 supporting the series of rollers 10, 20 is in the starting position, i.e. as close as possible to the point of approach of the shovel-loading means P.

Once the tray 6 has been filled, it is tipped above the series of rollers (Figures 10B, 1 1 B) and all the material contained therein is tipped out; the actual screening phase begins. The sorted material falls into the dumper body C; larger material is driven by the rollers 2 towards the unloading slide 9.

To prevent the dumper body C filling up closer to one side than the other, the overhead crane structure 1 1 supporting the series of rollers 10, 20 translates in a direction transversal to the axis of rotation x of the rollers, so as to position said rollers 2 above the part of the dumper body C that is still partially empty (Figures 10C, 1 1 C). After a series of overturns of the loading tray 6 and tipping of the material into the dumper body C, the screener 1 moves along the axis Z of the dumper C to enable the screened material to fall into the dumper body, filling it uniformly also in a longitudinal direction.

Loading operations will also be helped by video cameras and monitors in the command and control cabin housing the operator.

Once the dumper body C has been completely filled, the dumper moves and the screener 1 receives a new dumper C underneath, or else it moves around the mine to another extraction face (Figures 10D, 1 1 D).

Claims

1 . Mobile roller screener (1 ) for granular mined material comprising at least one first series of rollers (10), comprising a plurality of rollers (2), arranged parallel to one another on a same plane (ττ), each having a main axis of rotation (x), and motor means (13) adapted to rotate said rollers (2) in a coordinated manner around their axis (x), each roller (2) being provided with a plurality of shaped discs (3) mounted at regularly-spaced intervals, where said rollers (2) are separated from one another so that the space left between the shaped discs (3) acts as a discriminating factor for screening said granular mined material,

characterized in that said roller screener (1 ) comprises means of movement adapted to allow it to move around the working area.

2. Mobile roller screener (1 ) according to claim 1 , characterized in that said means of movement comprise a plurality of motorized, steered wheel assemblies (40).

3. Mobile roller screener (1 ) according to claim 1 , characterized in that it comprises a portal-like space structure (5), comprising a plurality of uprights (15) and cross members (16) adapted to support above ground said at least one first series of rollers (10).

4. Mobile roller screener (1 ) according to claim 3, characterized in that said portal-like space structure (5) comprises means for adjusting the length of said uprights (15) to change the working height of said at least one first series of rollers (10).

5. Mobile roller screener (1 ) according to claim 4, characterized in that said uprights (15) comprise a first (15') and a second (15") portion slidingly associated with one another, and said means of adjusting the length of said uprights (15) comprise lifting cylinders (23), adapted to act between said first (15') and said second (15") portion of said uprights (15).

6. Mobile roller screener (1 ) according to claim 4, characterized in that said means for adjusting the length of said uprights (15) comprise extendable articulated shock absorbers (24) connecting said means of movement and said uprights (15).

7. Mobile roller screener (1 ) according to claim 3, characterized in that said portal-like space structure (5) comprises translation means for said at least one first series of rollers (10), adapted to allow the movement of said at least one first series of rollers (10) in the containment plane (ττ), in a direction transversal to the main axis of rotation (x).

8. Mobile roller screener (1 ) according to claim 7, characterized in that said translation means comprise:

- an overhead crane structure (1 1 ) provided with support wheels (14) for said at least one first series of rollers (10);

- two rails (21 ) associated with said portal-like space structure (5) on which said overhead crane structure (1 1 ) can slide by means of said wheels (14);

- at least one hydraulic piston (22) placed between said portal-like structure (5) and said overhead crane structure (1 1 ), adapted to control the translation of said overhead crane structure (1 1 ) and the consequent movement of said at least one first series of rollers (10).

9. Mobile roller screener (1 ) according to claim 3, characterized in that it comprises a loading tray (6) for said granular mined material.

10. Mobile roller screener (1 ) according to claim 9, characterized in that said loading tray (6) is rotatingly associated with said portal-like structure (5) by means of a horizontal-axis hinged joint (7) parallel to the longitudinal axes (x) of said rollers (2), so as to be able to take up a position for loading said granular mined material underneath the plane (ττ) of said rollers (2), and a position for tipping the material above said at least one first series of rollers (10).

1 1 . Mobile roller screener (1 ) according to claim 1 0, characterized in that it comprises at least one hydraulic piston (8) placed between said portal-like structure (5) and said loading tray (6), adapted to control the movement of said loading tray (6) around said horizontal-axis hinged joint (7).

12. Mobile roller screener (1 ) according to claims 8 and 9, characterized in that said loading tray (6) is rotatingly associated with said at least one overhead crane structure (1 1 ) by means of a horizontal-axis hinged joint (7) parallel to the longitudinal axes (x) of said rollers (2), so as to be able to take up a position for loading said granular mined material underneath the plane (ττ) of said rollers (2) and a position for tipping the material above said at least one first series of rollers (10).

13. Mobile roller screener (1 ) according to claim 1 2, characterized in that it comprises at least one hydraulic piston (8) placed between said overhead crane structure (1 1 ) and said loading tray (6), adapted to control the movement of said loading tray (6) around said horizontal-axis hinged joint (7).

14. Mobile roller screener (1 ) according to claim 1 , characterized in that it comprises an unloading slide (9) for the granular mined material held and advanced above said rollers (2).

15. Mobile roller screener (1 ) according to claim 1 , characterized in that it comprises a second series of rollers (20), mounted specularly with respect to said first series (10).