EP3102331A1

EP3102331A1 - Mill for grinding metal materials

Info

Publication number: EP3102331A1
Application number: EP15708332.0A
Authority: EP
Inventors: Sperandio FRAPPORTI
Original assignee: Zato Srl
Current assignee: Zato Srl
Priority date: 2014-02-04
Filing date: 2015-02-03
Publication date: 2016-12-14
Also published as: WO2015118448A1

Abstract

A mill (1) for grinding materials comprising: a casing (3) defining an inner cavity (9) and delimiting an advancement path of the materials from an inlet section (10) to an outlet section (11) of the casing (3) through the inner cavity (9) and at least one rotor (4) arranged inside the cavity (9) and configured for rotating with respect to the casing (3), the rotor (4) comprising a shaft (24) engaged to the casing (3) for rotation around a main axis (A) and a plurality of grinding elements (25) associated with the shaft (24).

Description

DESCRIPTION

"MILL FOR GRINDING METAL MATERIALS"

The present invention relates to a mill for grinding and crushing metal materials; the invention has particular application in the field of mills for grinding aluminium scraps.

There are known machines (indicated in the art with the term "mills") for grinding metal materials, usually provided with a loading hopper, an outer cage, a rotor disposed inside the cage and an outlet section for the metal material ground by the mill. The rotor comprises a shaft on which hammers or stars can be mounted, these being elements capable of grinding the metal materials through their particular movement. The material to be ground is usually introduced into the loading hopper and, after being ground inside the cage through the action of the rotor, is evacuated from the mill through the outlet section. An example of a known mill is described in Italian patent application BS2006A000199, in the Applicant's name.

The known mills have drawbacks, such as non-optimal effectiveness in crushing materials and the difficulty of keeping the particle size of the materials under control. The known mills have further problems, such as complexity in the expulsion of material from the machine.

A principal object of the present invention is to resolve one or more of the problems found in the known art. One object of the present invention is to simplify the process of grinding metal materials and to make it more effective. A further object of the present invention is to facilitate and optimize the process of expelling the ground materials from the mill.

These and still other objects, which will become more apparent from the following description, are substantially achieved by a mill for grinding metal materials in accordance with what is expressed in one or more of the appended claims, taken on their own or in combination with one another or in combination with any of the further aspects or features described hereunder.

According to one or more aspects of the present invention, each of which can be taken on its own or in combination with any one of the claims or other aspects indicated hereunder, the invention can further relate to a mill for grinding materials wherein:

the mill is configured to grind metal materials;

the mill is configured to grind aluminium scraps;

the mill comprises a support structure;

the mill comprises at least one loading hopper;

the loading hopper is upstream of the inlet section of the casing;

the loading hopper is operatively connected to the inlet section of the casing;

the material is forced to enter at the inlet section of the casing by means of a pusher; the pusher is of a hydraulic or pneumatic type; the casing is constrained to the support structure;

the casing is at least partially fixed with respect to the support structure;

the outer casing comprises an upper portion and a lower portion;

the casing comprises at least one door for evacuating non-grindable materials from the casing;

the door for evacuating non-grindable materials from the casing is placed in a lower portion of the casing, below the rotor;

the door for evacuating non-grindable materials from the casing is configured to operate between at least a closed position and at least an open position;

the casing comprises at least an outer shell defining an outer surface of the casing, and at least an inner shell defining an inner surface of the casing;

the upper portion is movable with respect to the lower portion;

the upper portion is movable by means of a piston;

the upper portion of the casing rotates with respect to the lower portion of the casing; the piston configured to move the upper portion of the casing is of a hydraulic type; the lower portion is fixed with respect to the support structure;

the advancement path of the materials in the casing is defined starting from the inlet section of the materials in the casing, extends prevalently in a longitudinal and/or axial direction inside the cavity and ends at the outlet section for the exit of ground materials from the casing; the inlet section for the entry of material into the casing and the outlet section for the exit of material from the casing are in opposite positions with reference to the longitudinal extent of the casing;

the inner cavity of the casing is substantially cylindrical;

the inner surface of the casing is characterized by a greater surface hardness than the outer surface of the casing;

the shaft rotates about a substantially horizontal main axis;

the mill comprises at least one grinding stage;

the mill comprises a first and a second grinding stage, the second grinding stage being arranged in series with the first grinding stage along the advancement path of the materials inside the casing;

the mill comprises a third grinding stage arranged in series with the second grinding stage along the advancement path of the materials inside the casing;

the third grinding stage is interposed between the second grinding stage and the outlet section for the exit of ground materials from the casing _; the casing comprises at least one separating wall extending transversally with respect to the inner surface of the casing in interposition between two consecutive grinding stages;

the casing comprises a first and a second separating wall;

the first separating wall extends transversally with respect to an inner surface of the casing;

the first separating wall extends circumferentially with respect to the cavity, defining a wall shaped as a circular crown projecting from the inner surface of the casing in a direction that is substantially perpendicular thereto;

the first separating wall is interposed between the first and second grinding stages; the first separating wall is at least partially interposed between one or more terminal grinding elements of the first grinding stage and one or more initial grinding elements of the second grinding stage;

the first separating wall has a plurality of openings for a selective passage of the material from the first grinding stage to the second grinding stage;

the casing comprises a second separating wall extending transversally with respect to an inner surface of the casing;

the second separating wall extends circumferentially with respect to the cavity, defining a wall shaped as a circular crown projecting from the inner surface of the casing in a direction that is substantially perpendicular thereto;

the second separating wall is disposed in an outlet portion for the exit of materials from the second grinding stage;

the second separating wall is interposed between the second and third grinding stages; the second separating wall extends downstream of one or more terminal grinding elements of the second grinding stage;

the second separating wall has a plurality of openings for a selective passage of the material from the second grinding stage to the third grinding stage;

the openings of the first and/or of the second separating wall are substantially polygonal and/or substantially rectangular;

the openings of the first separating wall and/or the openings of the second separating wall have a free passage area comprised between 3000 mm2 and 5000 mm2 or between 3500 mm2 and 4500 mm2, preferably around 4000 mm2;

each of the openings of the second separating wall has a free passage area of smaller size than a free passage area of the openings of the first separating wall; the openings of the first separating wall are equally spaced along the circumferential extent of the first separating wall;

the openings of the second separating wall are equally spaced along the circumferential extent of the second separating wall;

the first separating wall comprises a number of openings in the range of between 8 and

18;

the second separating wall comprises a number of openings in the range of between 13 and 23;

the second separating wall comprises a larger number of openings than the first separating wall;

the rotor comprises a plurality of grinding elements associated with the shaft;

the grinding elements are connected to the shaft by means of connecting parts;

the connecting parts rotate integrally with the shaft;

the connecting parts comprise one or more discs, in particular one or more pairs of discs, and one or more pins;

the discs are mounted, in particular keyed, onto the shaft;

the discs are equally spaced longitudinally along the main rotation axis of the shaft; the discs rotate integrally with the shaft;

the first grinding stage comprises a first pair of discs;

the second grinding stage comprises a first respective pair of discs;

the first grinding stage comprises a second pair of discs, the second pair of discs being arranged in series with respect to the first pair of discs;

the second grinding stage comprises a second respective pair of discs, the second pair of discs being arranged in series with respect to the first pair of discs;

the first grinding stage comprises a first plurality of pairs of discs;

the second grinding stage comprises a second plurality of pairs of discs;

the discs have holes in an end portion thereof;

the discs have one or more holes in an end portion thereof;

each pair of discs has one or more pairs of homologous holes, in particular at least three pairs of homologous holes;

each pair of homologous holes of each pair of discs consists of two coaxial holes, each hole of the pair being defined in a disc of the pair of discs; each pair of holes comprises a first hole and a second hole, the first hole of each pair of holes being defined in a first disc of each pair of discs, the second hole of each pair of holes being defined in a second disc of each pair of discs;

each pair of discs has a plurality of pairs of homologous holes, each pair of holes comprising a first hole and a second hole, the first hole of each pair of holes being defined in a first disc of each pair of discs, the second hole of each pair of holes being defined in a second disc of each pair of discs;

the first and second holes of each pair of holes are aligned along a respective secondary axis that is substantially parallel to the main rotation axis of the shaft and spaced away from the main axis;

the first and second discs of each pair of discs are connected by at least one respective pin passing through the pair of discs in the first hole and in the second hole, the pin extending transversally with respect to the mutually facing faces of the respective pair of discs along the secondary axis;

the first and/or the second pair of discs and/or further pairs of discs are connected by one or more pins passing through the pairs of discs in one or more pairs of homologous holes; each pair of discs is passed through in the respective holes by at least a first, a second and a third pin;

at least one grinding element, in particular a plurality of grinding elements, is mounted on each pin;

the first, the second and the third pin pass through the pairs of discs of the first grinding stage and/or pass through the pairs of discs of the second grinding stage;

one or more pairs of discs of the first and/or of the second stage carry one or more grinding elements mounted on the respective pin;

each pair of discs of the first and/or of the second stage carries at least one grinding element mounted on the respective pin;

each pair of discs of the first and/or of the second stage carries a plurality of grinding elements, in particular three grinding elements, mounted on the respective pins;

the grinding elements are drawn in rotation by the shaft about the main rotation axis of the shaft;

each grinding element is engaged to the respective pin for rotation about the respective secondary axis; each grinding element has at least one through-hole of a size that is substantially equal to or greater than the diameter of the respective pin it is mounted upon, the respective pin passing through the grinding element in the through-hole;

each grinding element has a through-hole of a size that is greater than the diameter of the pin, each grinding element being engaged to the respective pin for translation and/or eccentric rotation about the secondary axis;

the grinding elements are mounted on the discs in eccentric positions with respect to the main rotation axis of the shaft;

one or more grinding elements extend at least partially in a gap defined between mutually facing faces of the discs of each pair of discs;

at the first and/or second and/or third grinding stage, the grinding elements comprise at least one selected from the group of: a plurality of grinding elements having a substantially star- shaped profile, a plurality of grinding elements having a hammer-shaped profile and a plurality of grinding elements having a profile characterized by at least one cutting surface;

the grinding elements having a profile characterized by at least one cutting surface comprise at least one tool, in particular a plurality of tools, selected from the group of: knives, blades and shears;

the grinding elements of the first and/or of the second grinding stage have a substantially star- and/or hammer-shaped profile;

the grinding elements of the first and/or of the second grinding stage are hammers and/or stars;

the hammers and/or stars are configured to rotate and/or rotate eccentrically and/or translate relative to a secondary axis along which the respective pins extend;

the rotor comprises a plurality of tools operatively associated with the shaft in a grinding stage, in particular at the third grinding stage;

the rotor comprises a plurality of first tools operatively associated with the shaft at a grinding stage, in particular at the third grinding stage;

the rotor comprises a plurality of second tools operatively associated with the shaft in a grinding stage, in particular at the third grinding stage, the second tools being in series with respect to the first tools with reference to the advancement path of the materials inside the casing;

the rotor comprises a plurality of third tools operatively associated with the shaft in a grinding stage, in particular the third grinding stage, the third tools being in series with respect to the second tools with reference to the advancement path of the materials inside the casing; the geometric profile of the tools is characterized by one or more cutting surfaces; the tools have a substantially quadrilateral geometric profile;

one or more cutting surfaces of the tools are defined on at least one end surface of the tool turned, in particular facing, toward the inner surface of the casing;

the rotor comprises a structure for supporting the tools;

the support structure comprises one or more discoidal elements;

the support structure comprises one or more supporting elements, the tools being configured to be constrained to the supporting elements;

each supporting element is configured to constrain a plurality of tools;

each supporting element is configured to constrain three tools, in particular a first tool, a second tool and a third tool, each supporting element extending axially in a direction substantially parallel to the main rotation axis of the shaft;

the tools are constrained to the supporting elements by connection means, such as screws and/or bolts;

the tools are removably constrained to the supporting elements;

the discoidal elements are mounted, in particular keyed, to the shaft at the third grinding stage;

the rotor comprises, at the third grinding stage, at least a first discoidal element keyed onto the shaft and rotating integrally with the shaft;

the rotor comprises, at the third grinding stage, a second discoidal element keyed onto the shaft and rotating integrally with the shaft;

the rotor comprises, at the third grinding stage, a third discoidal element and/or further discoidal elements, each discoidal element being keyed onto the shaft and rotating integrally with the shaft;

the support structure comprises one or more circular crowns mounted, in particular keyed, onto the respective discoidal elements;

the support structure comprises at least a first circular crown keyed to the first discoidal element;

the support structure comprises a second circular crown keyed to the second discoidal element;

the support structure comprises a third circular crown and/or further circular crowns keyed to the third discoidal element and/or to the respective discoidal element;

the first circular crown and/or the second circular crown and/or the third circular crown and/or further circular crowns comprise a plurality of housing seats for the tools; the first circular crown comprises a housing seat for each first tool;

the second circular crown comprises a housing seat for each second tool;

the third circular crown and/or further circular crowns comprise a housing seat for each third tool and/or further tools;

the housing seats for the tools, in the respective circular crowns, are arranged circumferentially in outer portions of the circular crowns;

each housing seat is suitable for housing at least one tool and a respective supporting element;

each housing seat for the first tools consists of a recess fashioned in an outer portion of the first circular crown;

each housing seat for the second tools consists of a recess fashioned in an outer portion of the second circular crown;

each housing seat for the third tools and/or of further tools consists of a recess fashioned in an outer portion of the third circular crown and/or of further circular crowns;

each recess has a substantially "U"-shaped profile;

one or more tools are mounted removably to the support structure in one or more housing seats;

the first tools and/or the second tools and/or the third tools and/or further tools are mounted in an adjustable, in particular radially adjustable, manner to the support structure in the respective housing seats;

the third grinding stage comprises a first discoidal element and/or a second discoidal element and/or a third discoidal element and/or further discoidal elements;

the third grinding stage comprises at least one circular crown configured to house a plurality of tools;

the third grinding stage comprises a first circular crown and/or a second circular crown and/or a third circular crown and/or further circular crowns;

the third grinding stage comprises a plurality of first tools and/or of second tools and/or of third tools and/or of further tools;

each first tool is positioned on the rotor at a first radial distance from the main rotation axis of the shaft and each second tool is positioned on the rotor at a second radial distance from the main rotation axis of the shaft, the second radial distance being greater than the first radial distance; the first and second radial distances are defined between the main rotation axis of the shaft and the cutting surface, respectively, of the plurality of first tools and the plurality of second tools;

each third tool is positioned on the rotor at a third radial distance from the main rotation axis of the shaft, the third radial distance being greater than the second radial distance;

the third radial distance is defined between the main rotation axis of the shaft and the cutting surface of the plurality of third tools;

the rotor has a maximum radial dimension that is variable along the advancement path of the materials inside the casing, in particular variable at the third grinding stage;

the maximum radial dimension of the rotor increases along the advancement path of the materials inside the casing, in particular it increases along the third grinding stage;

the maximum radial dimension of the rotor at the plurality of second tools is greater than the maximum radial dimension of the rotor at the plurality of first tools;

the maximum radial dimension of the rotor at the plurality of third tools is greater than the maximum radial dimension of the rotor at the plurality of second tools;

each tool of the plurality of first tools and/or of second tools and/or of third tools and/or of further tools has a respective length, the length being defined transversally with respect to the main rotation axis of the shaft, in particular radially with respect to the rotor;

the plurality of first tools extends for a first length and the plurality of second tools extends for a second length, the second length being greater than the first length;

the plurality of third tools extends for a third length greater than the second length; the tools are knives;

the casing has a toothing emerging from the inner surface of the casing toward the cavity;

the toothing is defined in the internal shell of the casing in a grinding stage, in particular the third grinding stage;

the toothing is disposed perimetrally and/or circumferentially with respect to the cavity in the internal shell of the casing;

the toothing comprises alternating recesses and teeth;

each tooth extends in interposition between two recesses;

each tooth extends longitudinally along a direction substantially parallel to the main rotation axis of the shaft;

the teeth emerge transversally from the inner surface of the casing, defining a radial dimension toward the cavity; the toothing comprises a first plurality of teeth and/or a second plurality of teeth and/or a third plurality of teeth and/or a further plurality of teeth;

the first plurality of teeth, the second plurality of teeth, the third plurality of teeth and/or further plurality of teeth are disposed along the perimetral and/or circumferential extent of the inner surface of the casing;

the second plurality of teeth is arranged in series with respect to the first plurality of teeth along the advancement path of the materials inside the casing;

the third plurality of teeth is arranged in series with respect to the second plurality of teeth along the advancement path of the materials inside the casing;

the first plurality of teeth is disposed around the plurality of first tools;

the first plurality of teeth emerges from the inner surface of the casing for a first depth; the first depth of the first plurality of teeth is in the range of between 5 and 10 mm; the first depth of the first plurality of teeth is substantially equal to 7 mm;

the second plurality of teeth is disposed around the plurality of second tools;

the second plurality of teeth emerges from the inner surface of the casing for a second depth;

the second depth of the second plurality of teeth is in the range of between 2 and 8 mm; the second depth of the second plurality of teeth is substantially equal to 5 mm;

the second depth of the second plurality of teeth is less than the first depth of the first plurality of teeth;

the third plurality of teeth is disposed around the plurality of third tools;

the third depth of the third plurality of teeth is in the range of between 1 and 6 mm; the third depth of the third plurality of teeth is substantially equal to 3 mm;

the third depth of the third plurality of teeth is less than the second depth of the second plurality of teeth;

the cutting surface of the first tools delimits, with the inner surface of the casing, a first radial gap;

the first radial gap is defined between the crest of the teeth of the first plurality of teeth and the cutting surface of the plurality of first tools;

the first gap has a first height defined between the cutting surface of the first tools and the teeth of the first plurality of teeth at the point of the maximum radial dimension thereof;

the first height of the first gap is in the range of between 5 and 10 mm;

the first height of the first gap is substantially equal to 7 mm; the cutting surface of the second tools delimits, with the inner surface of the casing, a second radial gap;

the first radial gap has a free passage section having a greater area than the area of the free passage section of the second radial gap;

the second radial gap is defined between the crest of the teeth of the second plurality of teeth and the cutting surface of the plurality of second tools;

the second gap has a second height defined between the cutting surface of the second tools and the teeth of the second plurality of teeth at the point of the maximum radial dimension thereof;

the second height of the second gap is in the range of between 2 and 8 mm;

the second height of the second gap is substantially equal to 5 mm;

the second height of the second gap is less than the first height of the first gap;

the cutting surface of the third tools delimits, with the inner surface of the casing, a third radial gap;

the second radial gap has a free passage section having a greater area than the area of the free passage section of the third radial gap;

the third radial gap is defined between the crest of the teeth of the third plurality of teeth and the cutting surface of the plurality of third tools;

the third gap has a third height defined between the cutting surface of the third tools and the teeth of the third plurality of teeth at the point of the maximum radial dimension thereof; the third height of the third gap is in the range of between 1 and 6 mm;

the third height of the third gap is substantially equal to 3 mm;

the third height of the third gap is less than the second height of the second gap;

the mill comprises suction means working downstream of the outlet section for the exit of materials from the casing;

the suction means are configured to suck the materials out of the casing;

the suction means are operatively connected to the outlet section for the exit of materials from the casing;

the evacuation conduit is disposed downstream of the outlet section for the exit of materials from the casing;

the suction means are disposed downstream of the evacuation conduit;

the suction means are operatively connected to the outlet section for the exit of materials from the casing via the evacuation conduit;

the suction means comprise a cyclone separator; downstream of the suction means there is disposed at least one filtering element configured to separate the different materials sucked out and/or the different phases present in the materials exiting the casing;

the filtering element comprises a filter configured to separate dust from gases, preferably a baghouse filter.

According to one or more aspects of the present invention, each of which can be taken on its own or in combination with any one of the claims or of the other aspects, the invention can further relate to a mill for grinding materials wherein:

the mill for grinding materials comprises:

o a casing comprising an inlet section and an outlet section for the exit of materials from the casing, the casing defining an inner cavity and delimiting an advancement path of the materials from the inlet section to the outlet section of the casing through the inner cavity;

o at least one rotor disposed inside the cavity and configured to rotate with respect to the casing, the rotor comprising a shaft engaged to the casing for rotation around a main axis and a plurality of grinding elements associated with the shaft,

said mill comprising at least a first and a second grinding stage, the second grinding stage being arranged in series with respect to the first grinding stage along the advancement path of the materials inside the casing, the casing further comprising at least one separating wall extending transversally with respect to an inner surface of the casing, the separating wall being interposed between the first and second grinding stages and having a plurality of openings for a selective passage of the material from the first stage to the second grinding stage;

the separating wall emerges from the inner surface of the casing toward the cavity and/or extends perimetrally with respect to the cavity;

the cavity is substantially cylindrical and the separating wall extends circumferentially with respect to the cavity, defining a wall shaped as a circular crown emerging from the inner surface of the casing in a direction substantially perpendicular thereto;

the mill comprises connecting parts between the grinding elements and the shaft and/or wherein the connecting parts comprise a plurality of discs keyed onto the shaft so as to be at least rotationally constrained to the shaft itself;

the plurality of discs comprises one or more pairs of adjacent discs, each pair of discs carrying one or more grinding elements which extend at least partially in a gap defined between mutually facing faces of the discs of said pair of discs and/or wherein each pair of discs has at least a first pair of homologous through-holes comprising a first hole and a second hole, the first hole being defined in a first disc of said pair of discs, the second hole being defined in a second disc of said pair of discs, the first and second holes being aligned along a secondary axis substantially parallel to the main rotation axis of the shaft and spaced away from the main axis, the first and second discs being connected by at least one respective pin passing through the pair of discs in the first hole and in the second hole, the respective pin extending transversally with respect to the mutually facing faces of the discs of the pair of discs along the secondary axis;

the first grinding stage comprises at least a first pair of discs and the second grinding stage comprises at least a first respective pair of discs, each pair of discs carrying at least two grinding elements;

the grinding elements at the first and/or the second grinding stage comprise at least one selected from the group of: a plurality of grinding elements having a substantially star-shaped profile, a plurality of grinding elements having a hammer-shaped profile and a plurality of grinding elements having a profile characterized by at least one cutting surface;

said at least one separating wall comprises a first and a second separating wall, the first separating wall extending in interposition between the first and second grinding stages, the second separating wall extending in an outlet portion for the exit of materials from the second grinding stage, the first separating wall having a plurality of openings for the passage of the material from the first stage to the second grinding stage and the second separating wall having a respective plurality of openings for the exit of the material from the second grinding stage; each of the openings of the second separating wall has a free passage area of smaller size than a free passage area of the openings of the first separating wall.

the mill for grinding materials comprises:

o a casing comprising an inlet section and an outlet section for the exit of materials from the casing, the casing defining an inner cavity and delimiting an advancement path of the materials from the inlet section to the outlet section of the casing;

o at least one grinding stage of the materials disposed in said inner cavity between the inlet section and the outlet section;

o at least one rotor disposed inside the cavity and configured to rotate with respect to the casing, the rotor comprising: a shaft mounted for rotation around a main axis with respect to said casing, a plurality of first tools operatively associated with the shaft at the grinding stage, each of said first tools having at least one cutting surface turned toward an inner surface of the casing, a plurality of second tools operatively associated with the shaft at the grinding stage and in series with the first tools, each of said second tools having at least one cutting surface turned toward an inner surface of the casing,

wherein the cutting surface of the first tools delimits, with the inner surface of the casing, a first radial gap, wherein the cutting surface of the second tools delimits, with the inner surface of the casing, a second radial gap consecutively disposed with respect to the first gap, and wherein the first gap has a free passage section having a greater area than the area of the free passage section of the second gap;

the rotor comprises a plurality of third tools and/or a further plurality of tools, the tools having at least one cutting surface turned toward an inner surface of the casing, the cutting surface of the tools of each plurality of tools delimiting, with the inner surface of the casing, a respective radial gap;

the gap between the cutting surfaces of the tools and the inner surface of the casing gets thinner along the advancement path of the material inside the casing;

the casing has a toothing emerging transversally from the inner surface of the casing toward the cavity and disposed perimetrally and/or circumferentially with respect to the cavity; the toothing comprises alternating recesses and teeth, each tooth extending in interposition between two recesses and/or extending longitudinally along a direction that is substantially parallel to the main rotation axis;

the toothing comprises a first plurality of teeth and a second plurality of teeth, the second plurality of teeth being arranged in series with respect to the first plurality of teeth along the advancement path of the materials inside the casing, each tooth of the first plurality of teeth and each tooth of the second plurality of teeth emerging transversally from the inner surface of the casing for a first depth and for a second depth, respectively, the second depth being less than the first depth;

the toothing comprises a third plurality of teeth and/or a further plurality of teeth, each tooth emerging transversally from the inner surface of the casing for a respective depth, the depth of the teeth decreasing along the advancement path of the material inside the casing in at the grinding stage;

the first plurality of teeth is arranged along the perimetral and/or circumferential extent of the inner surface of the casing, in particular around the plurality of first tools, and wherein the second plurality of teeth is disposed along the perimetral and/or circumferential extent of the inner surface of the casing, in particular around the plurality of second tools;

the rotor comprises, at the grinding stage, a support structure for the first tools and for the second tools, the support structure rotating integrally with the shaft.

the mill for grinding materials comprises:

o an outer casing comprising an inlet section and an outlet section for the exit of materials from the casing, the casing defining an inner cavity and delimiting an advancement path of the materials from the inlet section to the outlet section of the casing;

o at least one rotor disposed inside the cavity and configured to rotate with respect to the outer casing, the rotor comprising a shaft and a plurality of grinding elements associated with the shaft,

said mill being characterized in that it comprises suction means for the materials working downstream from the outlet section of the casing, the suction means being configured to suck the materials out of the casing;

the mill comprises at least one conduit for evacuating the materials from the casing; the evacuation conduit is disposed downstream of the outlet section for the exit of materials from the casing;

the suction means are disposed downstream of the evacuation conduit;

the suction means comprise a cyclone separator;

downstream of the suction means there is disposed at least one filtering element configured to separate the different materials sucked out and/or the different phases present in the materials exiting the casing;

the filtering element comprises a filter configured to separate dust from gases, preferably a baghouse filter

According to one or more aspects of the present invention, each of which can be taken on its own or in combination with any one of the claims or of the other aspects, the invention can further relate to a process for grinding metal materials, wherein the process comprises at least the step of:

providing a mill according to any one of the preceding aspects; and/or feeding metal material to be ground into the inlet section of the casing ; and/or actuating the rotor in rotation so as to grind the metal material; and/or

grinding the material at the first grinding stage; and/or

enabling a passage, through the plurality of openings of the separating wall, in particular of the first separating wall, of a fraction of ground material having a particle size equal to or smaller than a first particle size, the first particle size being correlated to a passage area of the openings of the separating wall; and/or

further grinding the material at the second grinding stage; and/or

enabling a passage, through the plurality of openings of the second separating wall, of a fraction of ground material having a particle size equal to or smaller than a second particle size, the second particle size being correlated to a passage area of the openings of the second separating wall, preferably the second particle size being smaller than the first particle size. According to one or more aspects of the present invention, each of which can be taken on its own or in combination with any one of the claims or of the other aspects, the invention can further relate to a process for grinding metal materials, wherein the process comprises at least the step of:

providing a mill according to any one of the preceding aspects; and/or

feeding metal material to be ground into the inlet section of the casing ; and/or actuating said rotor in rotation so as to grind the metal material; and/or

grinding the metal material in the first gap; and/or

grinding the metal material in the second gap; and/or

grinding the metal material in the third gap.

According to one or more aspects of the present invention, each of which can be taken on its own or in combination with any one of the claims or of the other aspects, the invention can further relate to a process for grinding metal materials wherein the process comprises at least the step of:

providing a mill according to any one of the preceding aspects; and/or

evacuating ground material from said outlet section, said evacuation step comprising a suction step carried out by the suction means.

According to further aspects of the present invention, each of which can be taken on its own or in combination with any one of the claims or of the preceding aspects, in the process according to the present invention: the step of loading the metal material comprises a step of forcing the material to enter the casing in an inlet section; and/or

the step of forcing the material to enter the casing in an inlet section is carried out by means of a pusher.

There now follows, by way of non-limiting example, the detailed description of one or more preferred embodiments of the invention, in which:

- figure 1 represents a front perspective view of a mill according to one embodiment of the present invention, wherein the casing is in a first closed configuration;

- figure 2 represents a rear perspective view of a mill according to one embodiment of the present invention, wherein the casing is in a second open configuration;

- figure 3 represents a rear view of a mill according to one embodiment of the present invention, wherein the casing is in a second open configuration;

- figure 4 represents the rotor housed inside the casing of a mill according to one embodiment of the present invention;

- figure 5 represents a section of the mill according to one embodiment of the present invention, drawn across the rotor and the casing;

- figure 6 represents a view of the rotor of a mill according to one embodiment of the present invention;

- figure 7 represents the upper portion of the casing of a mill according to one embodiment of the present invention in a second open configuration;

- figure 8 represents a sectional view of the casing of a mill according to one embodiment of the present invention;

- figure 9 represents the casing of a mill according to one embodiment of the present invention;

- figure 10 represents a detail of the tools of a mill according to one embodiment of the present invention;

- figure 11 represents a view of the rotor of a mill according to one embodiment of the present invention illustrating the first and the second grinding stage;

- figure 12 represents a view of the rotor of a mill according to one embodiment of the present invention illustrating the third grinding stage;

- figure 13 represents a view of a pair of discs of the rotor of a mill according to one embodiment of the present invention;

- figure 14 represents a view of two pairs of discs of the rotor of a mill according to one embodiment of the present invention; - figure 15 represents a detail of the tools in figure 10;

- figure 16 represents three tools of the rotor of a mill according to one embodiment of the present invention;

- figure 17 represents a section of the casing of a mill according to one embodiment of the present invention in a first closed configuration;

- figure 18 represents a front view of a circular crown of the support structure of the tools;

- figure 19 represents a view of a first and a second circular crown mounted on a first and a second discoidal element, respectively;

- figure 20 represents a view illustrating the first radial gap between the plurality of first tools and the first plurality of teeth;

- figure 21 represents a detailed view of a radial gap between the toothing emerging from the inner surface of the casing and the plurality of tools;

- figure 22 represents a view illustrating the second radial gap between the plurality of second tools and the second plurality of teeth;

- figure 23 represents a view illustrating the third radial gap between the plurality of third tools and the third plurality of teeth;

- figure 24 represents a section of the casing and of the rotor of a mill according to one embodiment of the present invention;

- figure 25 represents a front view of a mill according to one embodiment of the present invention with some parts removed in order to show the door set below the casing.

With reference to the figures, 1 denotes overall a mill for grinding metal materials, in particular aluminium. The mill 1 comprises a loading hopper 2, an outer casing 3, a rotor 4 rotatingly housed inside the outer casing 3 and one or more portions 5 for evacuating the ground and/or unground metal material from the mill 1. The mill 1 further comprises a support structure 6 and can comprise means 7 configured to rotate the rotor 4, as illustrated in figure 1.

The loading hopper 2 forms the portion for introducing the material to be crushed to the inside of the mill 1 ; after the material is loaded into the hopper 2, the material is conveyed toward the inside of the casing 3. The material to be crushed can be forced to enter the casing 3 via a pusher 8, preferably of a hydraulic type, which is configured to push the material loaded in the hopper 2 so that it comes into contact with the rotor 4. The metal material, therefore, after having been introduced into the mill 1 through the hopper 2, is conveyed along an advancement path defined inside the casing 3.

The casing 3 represents the element of the mill 1 inside which the crushing of the material introduced in the hopper 2 takes place. From a structural viewpoint, the casing 3 defines an inner cavity 9 inside which the rotor 4 is rotatingly housed and the rotor is therefore configured to rotate with respect to the outer casing 3; preferably, the casing 3 and/or the cavity 9 are substantially cylindrical. The casing 3 further has an inlet section 10 for the entry of the metal material to be crushed in the casing 3 and an outlet section 11 for the exit of the crushed material from the casing 3; in interposition between the inlet section 10 and the outlet section 11 , the casing 3 delimits an advancement path of the materials through the inner cavity 9. Under operating conditions of the mill 1, the material processed inside it thus passes through the casing 3 along the advancement path starting from the inlet section 10 and proceeding toward the outlet section 11, while being ground along the path itself. The mill 1 can comprise one or more grinding stages, which can be defined and extend in a series inside the casing 3; each grinding stage can differ from the others in terms of the geometry of the rotor 4 and/or of the casing 3 and/or of the particle size of the material exiting the grinding stage. In particular, the mill 1 comprises at least a first and a second grinding stage 12, 13; the second grinding stage 13 is arranged in series with respect to the first grinding stage 12 along the advancement path of the materials inside the casing 3. In series with the second grinding stage 12, the mill can further comprise a third grinding stage 14. Figure 5, for example, shows a section of a mill 1 that comprises a first, a second and a third grinding stage 12, 13, 14. Preferably, at the first grinding stage 12, the material is ground into a first particle size and at the second grinding stage 13 the material is ground into a second particle size; the second particle size can be smaller than the first particle size.

From a structural viewpoint, the casing 3 has an inner surface 15 turned toward the cavity 9 and an outer surface 16; preferably, the casing 3 comprises at least an inner shell 17 defining the inner surface 15 of the casing and at least an outer shell 18 defining the outer surface 16 of the casing. The casing 3 further has an upper portion 19 and a lower portion 20; the upper portion 19 of the casing 3 can be moved, for example, by rotating with respect to the lower portion 20, which can be fixed with respect to the support structure 6. The upper portion 19 can be moved with respect to the lower portion 20, for example by means of a piston 21 , between a closed position and an open position. Depending on the reciprocal positioning between the upper portion 19 and lower portion 20, the casing 3 can take on a first closed configuration and a second open configuration corresponding, respectively, to the closed position and to the open position of the upper portion 19. The first closed configuration of the casing 3 is illustrated, for example, in figure 1 , whilst the second open configuration is illustrated in figure 2 and in figure 3; in the open configuration the rotor 4 is substantially accessible from the outside of the casing 3, for example for maintenance.

The casing 3 can comprise a first separating wall 22, which can extend outward from the inner surface 15 of the casing 3 and in particular emerge transversally from the inner surface 15 of the casing 3 toward the cavity 9. The first separating wall 22 can extend perimetrally and/or circumferentially with respect to the cavity 9, thus defining a wall shaped as a circular crown emerging from the inner surface 15 of the casing 3; in particular, the first separating wall 22 emerges in a direction that is substantially perpendicular to the inner surface 15 of the casing 3. Preferably, the first separating wall 22 is interposed between the first and second grinding stages 12, 13, as illustrated in figure 5 and in figure 24.

The first separating wall 22 can further have a plurality of through openings 220, which can be configured for a selective passage of material having dimensions equal to or smaller than the first particle size. To make this passage possible, the first particle size can be correlated to a passage area of the openings 220 of the first separating wall 22; in particular, the first particle size can be less than one or more dimensions characterizing the openings 220 of the first separating wall 22. In other words, the openings 220 of the first separating wall 22 can be of any form configured to enable a selective passage of material having the first particle size from the first grinding stage 12 to the second grinding stage 13. Preferably, the openings 220 of the first separating wall 22 are equally spaced apart along the perimetral and/or circumferential extent of the first separating wall 22 with respect to the cavity 9.

The material ground at the first grinding stage 12, if of suitable dimensions, passes through the first separating wall 22 at the openings 220, then arriving at the second grinding stage 13, where it is further crushed and broken down.

Downstream of the second grinding stage 13, the casing 3 can comprise a second separating wall 23, which can extend in an outlet portion for the exit of materials from the second grinding stage 13. The second separating wall 23 can extend transversally with respect to an inner surface 15 of the casing 3, in particular emerging from the inner surface 15 of the casing 3 toward the cavity 9. The second separating wall 23 can extend perimetrally and/or circumferentially with respect to the cavity 9, thus defining a wall shaped as a circular crown emerging from the inner surface 15 of the casing 3; in particular, the second separating wall 23 emerges in a direction that is substantially perpendicular to the inner surface 15 of the casing 3. The second separating wall 23 is preferably interposed between the second grinding stage 13 and the third grinding stage 14, as illustrated in figure 5 and in figure 24.

The second separating wall 23 can have a plurality of through openings 230, which can be configured for a selective passage of material of dimensions that are equal to or smaller than the second particle size. To make this passage possible, the second particle size can be correlated to a passage area of the openings 230 of the second separating wall 23; in particular, the second particle size can be less than one or more dimensions characterizing the openings 230 of the second separating wall 23. In other words, the openings 230 of the second separating wall 23 can be of any form configured to enable a selective passage of material having the second particle size through the outlet of the second grinding stage. Preferably, the openings 230 of the second separating wall 23 can be equally spaced apart along the perimetral and/or circumferential extent of the second separating wall 23 with respect to the cavity 9.

The material ground at the second grinding stage 13, if of suitable dimensions, passes through the second separating wall 23 at the openings 230, so as then to be conveyed toward a further grinding stage, that is, a third grinding stage 14 provided inside the casing 3 in series with the second grinding stage 13, or else be evacuated from the mill 1.

From a dimensional viewpoint, the openings 220 of the first separating wall 22 and/or the openings 230 of the second separating wall 23 can have a free passage area in the range of between 3000 mm² and 5000 mm² or between 3500 mm² and 4500 mm², preferably around 4000 mm². In particular, the openings 230 of the second separating wall 23 can have a free passage area of smaller size than a free passage area of the openings 220 of the first separating wall 22. The element of the mill 1 responsible for moving and grinding the metal material inside the casing 3 is the rotor 4; in particular, grinding of the metal material takes place by the forcing of the material between the casing 3 and rotor 4 as a result of the movement of the rotor 4 with respect to the casing 3.

From a structural viewpoint, the rotor 4 comprises a shaft 24 and a plurality of grinding elements 25; the shaft 24 rotates around a main axis A and the grinding elements 25 rotate integrally with the shaft 24. The grinding elements 25, by repeatedly striking the materials introduced into the casing 3 at the respective grinding stage, determine the grinding thereof into parts of a particle size that gets increasingly smaller along the advancement path of the material inside the casing 3. The grinding elements 25 can work on the material to be ground according to two main methods; the first consists in impacting the material and consequently forcing it against the inner surface 15 of the casing 3, whilst the second consists in tearing and cutting the material itself via cutting surfaces of one or more grinding elements 25. In general, the grinding elements acting according to the first grinding method are prevalently hammers and/or stars, whereas the grinding elements acting in accordance with the second grinding method are prevalently knives. In the context of the present description, hammers, stars and knives mean grinding elements having a precise meaning in the art related to the grinding of metal materials. In the context of the present invention, each grinding element 25 can have a substantially star-shaped profile or a hammer-shaped profile or a profile characterized by at least one cutting surface; preferably, the grinding elements 25 are stars 251 and/or knives 252 and/or hammers (not illustrated in the figure). For example, figure 4 illustrates a rotor 4 comprising a plurality of stars 251 at the first and second grinding stages 12, 13 and a plurality of knives 252 at the third grinding stage 14. The grinding elements 25, besides rotating integrally with the shaft 24, can also rotate with respect to a secondary axis that is substantially parallel to the main axis A and spaced away from it; in particular, the grinding elements 25 can rotate eccentrically and/or translate with respect to the secondary axis. From a structural viewpoint, the grinding elements 25 can be connected to the shaft 24 by means of connecting parts 26, which are integral with the shaft 24; in other words, the connecting parts 26 can rotate integrally with the shaft 24 around the main axis A. The connecting parts 26 can comprise one or more discs 27, in particular a plurality of discs 27 keyed onto the shaft 24, and one or more pins 28 configured to connect one or more discs 27 and one or more grinding elements 25. The discs 27 can be mounted in different axial positions with respect to the longitudinal extent of the shaft 24, preferably at a same distance from one another. In particular, the plurality of discs 27 can comprise one or more pairs of discs 27; each pair of discs 27 consists of two adjacent discs 27 along the longitudinal extent of the shaft 24 and can carry at least one grinding element 25, in particular a plurality of grinding elements 25. The grinding elements 25 can extend at least partially in a gap defined between mutually facing faces of the discs 27 of a pair of discs 27, as illustrated for example in figure 11.

Each pair of discs 27 can comprise a first and a second disc 278, 279, which are adjacent and facing each other, and have one or more holes 29, in particular at least a first pair 291 of homologous through-holes 29. The first pair 291 of holes 29 can comprise a first hole 298 defined in the first disc 278 and a second hole 299 defined in the second disc 279, as illustrated in figure 13; preferably, the first and second holes 298, 299 are aligned along a secondary axis substantially parallel to the main rotation axis A of the shaft 24 and spaced away from it. In particular, the first and second discs 278, 279 can be connected by at least one respective pin 28 passing through the pair of discs 27 in the first and of the second holes 298, 299; the respective pin 28 can therefore extend transversally with respect to the mutually facing faces of the discs of the pair of discs 27 along the secondary axis common to the first and second holes 298, 299. Within a same pair of discs 27, the second disc 279 is disposed downstream and in series with respect to the first disc 278 with reference to the advancement path of the materials inside the casing 3; the arrangement in series of the first and second discs 278, 279 is for example illustrated in figure 13. In particular, with respect to two adjacent pairs of discs 27, i.e. a first and a second pair 271 , 272 of discs 27, wherein the second pair 272 of discs 27 is arranged downstream and in series with respect to the first pair 271 of discs 27 with reference to the advancement path of the materials inside the casing 3, a same disc 27 can act as the second disc 279 of the first pair 271 of discs 27 and the first disc 278 of the second pair 272 of discs 27. In other words, two pairs of discs 27 can also be defined by only three adjacent discs 27, since the central disc belongs to both adjacent pairs; for example, figure 14 shows the three discs 27 which form the first and the second pair of discs 271 , 272.

With respect to the pins 28, at least one grinding element 25 can be mounted on each of them, in particular in the portion of the pin 28 extending in the gap defined between the mutually facing faces of the discs of a pair of discs 27. The pin 28 can pass through the grinding element 25 in a through-hole 295 of the grinding element 25 of dimensions that are substantially equal to a diameter of the pin 28; in other words, the hole 295 of the grinding element 25 can be characterized by dimensions such that the grinding element 25 can be engaged to the pin 28 to enable at least the rotation thereof about the pin 28 itself. Preferably, the through-hole 295 of the grinding element 25 can have dimensions that are larger than the diameter of the pin 28 (coupling with play), so as to enable the grinding element 25 to translate and/or rotate eccentrically about the pin 28 itself. In other words, the respective diameter size of the hole 295 of the grinding element 25 and of the respective pin 28 can be such that the grinding elements 25 can be mounted on the respective pins 28 in such a way as to be free to rotate or rotate eccentrically and/or translate with respect to the respective pins 28. For example, the rotor 4 can comprise a plurality of grinding elements 25, in particular stars 251, each of which can be endowed with a hole 295 of dimensions that are larger than the diameter of the pin 28 which passes through it precisely in the respective hole 295; this feature is visible in particular with reference to the star 251 in the foreground of figure 4.

The rotor 4 can further have a plurality of pairs of discs 27, each of which can be endowed with a plurality of pairs of homologous holes 29 suitable for accommodating a plurality of respective pins 28, each of which can be engaged to at least one grinding element 25. In other words, each pair of discs 27 can have a plurality of pairs of homologous holes 29 configured to accommodate a respective pin 28 extending along the secondary axis transversally with respect to the mutually facing faces of the discs of the respective pair of discs 27. In particular, the pairs of discs 27 of the rotor 4 can have respectively at least a first, a second and/or a third pair 291 , 292, 293 of holes 29, which can be aligned along respective secondary axes that are substantially parallel to the main axis A and spaced away from it. The first, second and third pairs 291 , 292, 293 of holes 29 can be positioned in the respective discs 27 at a same radial distance from the main rotation axis A of the shaft. Preferably, each first, second and third pair 291 , 292, 293 of holes can comprise a first hole 298 defined in the first disc 278 and a second hole 299 defined in the second disc 279; preferably, each first and each second hole 298, 299 of each pair of holes are aligned along a secondary axis that is substantially parallel to the main rotation axis A of the shaft 24 and spaced away from it.

In particular, the first holes 298 of the first, second and third pairs 291 , 292, 293 of holes 29 can be positioned at 120° from one another in a same first disc 278 and/or the second holes 299 of the first, second and third pairs 291 , 292, 293 of holes 29 can be respectively positioned at 120° from one another in a same second disc 279; this reciprocal geometric positioning of the holes 29 is for example illustrated in figure 13. The respective angular and radial positioning of the holes 29 enables the alignment of the homologous holes 29 of each pair and consequently the mounting of the pins 28 in the homologous aligned holes 29. For example, the pairs of discs 27 of the rotor 4 can be passed through by a first, a second and/or a third pin 281 , 282, 283, which can be respectively accommodated in the first, second and third pairs 291 , 292, 293 of holes 29 and can extend longitudinally with respect to the rotor 4 along the respective secondary axes. With regard to the first and second grinding stages 12, 13, they can be composed of one or more pairs of discs 27 endowed with one or more pairs of holes 29, each of which can be passed through by a pin 28; at least one grinding element 25 can be mounted on each pin 28. Each grinding stage can comprise at least one pair of discs 27 which carries at least two grinding elements 25; each grinding element 25 can extend at least partially in a gap defined between mutually facing faces of the discs 27 of the respective pair of discs 27. From the viewpoint of the geometry of the rotor 4, the first and second grinding stages 12, 13 can thus be similar; they can differ not only in their respective positioning inside the casing 3 (the first and second stages 12, 13 are respectively upstream and downstream of the first separating wall 22 with reference to the advancement path of the materials inside the casing 3) but also in the number of the pairs of discs 27 and/or number of grinding elements 25. Preferably, the first grinding stage 12 has a first plurality of pairs of discs 27 and the second grinding stage 13 has a second plurality of pairs of discs 27; the first plurality of discs 27 can be characterized by a number of pairs of discs 27 that is greater than the number of pairs of discs 27 of the second plurality of pairs of discs 27.

With reference to the discs 27 of one or more adjacent pairs of discs, they can be joined by means of a same pin 28 passing through pairs of homologous coaxial holes 29 of each pair of discs 27. The transverse pin 28 passing through two or more pairs of discs 27 can extend along the first and/or second grinding stages 12, 13; in particular, in a series of pairs of holes 29 aligned along a same secondary axis, the pairs of discs 27 of the first grinding stage 12 and the pairs of discs 27 of the second grinding stage 13 can be passed through by a same pin 28, which can extend both along the first grinding stage 12 and along the second grinding stage 13 in a direction that is substantially parallel to the main axis A. Preferably, the pairs of discs 27 of the first and second grinding stages 12, 13 are passed through in pairs of homologous coaxial holes 29 by a plurality of pins 28, for example three pins 28.

As said previously, the first separating wall 22 is interposed between the first and second grinding stages 12, 13; with reference to the positioning thereof with respect to the rotor 4, the first separating wall 22 can extend between one or more grinding terminal elements 25 of the first grinding stage 12 and one or more initial grinding elements 25 of the second grinding stage 13, as illustrated in figure 24. With regard, on the other hand, to the second separating wall 23, it can extend downstream of one or more grinding terminal elements 25 of the second grinding stage 13, as illustrated in figure 24. Initial grinding elements 25 of a grinding stage means the first grinding elements 25 with which the material comes into contact upon entering the grinding stage, whilst terminal grinding elements 25 of a grinding stage means the grinding elements 25 that the material, as it proceeds along the portion of the advancement path thereof inside the casing 3 defined at the grinding stage, meets last before going beyond the grinding stage itself. In other words, the initial and terminal grinding elements 25 of a same grinding stage are disposed, respectively, in an inlet portion and an outlet portion for the entry/exit of materials into/from the grinding stage.

The rotor 4 can further comprise a plurality of tools 30, preferably a plurality of first tools 301 and a plurality of second tools 302 operatively associated with the shaft 24; in particular, the plurality of second tools 302 is arranged in series with respect to the plurality of first tools 301 with reference to the advancement path of the material inside the casing 3. The rotor 4 can have the pluralities of first and second tools 301 , 302 at a same grinding stage, which can for example be the third grinding stage 14 (disposed preferably in series with the second grinding stage 13 along the advancement path of the materials inside the casing 3) or another grinding stage.

With reference to the profile of the tools 30, it can be at least partially sharp; in particular, each tool 30 has at least one cutting surface 31 , which can be turned, in particular facing, toward an inner surface 15 of the casing 3 and can delimit therewith a radial gap 32. The gaps 32 are defined between the cutting surface 31 of the tools 30 and the inner surface 15 of the casing 3; preferably, the gaps 32 are defined between a plurality of protuberances, in particular teeth, emerging from the inner surface 15 of the casing 3 itself and the cutting surface 31 of the tools 30, as illustrated in figure 21. In particular, the cutting surface 31 of the first tools 301 delimits, with the inner surface 15 of the casing 3, a first radial gap 321 and the cutting surface 31 of the second tools 302 delimits, with the inner surface 15 of the casing 3, a second radial gap 322; the first gap 321 and the second gap 322 are respectively illustrated in figure 20 and in figure 22. Preferably, the first gap 321 has a free passage section having a greater area than the area of the free passage section of the second gap 322. Each radial gap is characterized by a distance between the cutting surface 31 of each tool 30 and the inner surface 15 of the casing 3. In particular, the distance between the cutting surface 31 of each first tool 301 and the inner surface 15 of the casing 3 is greater than the distance between the cutting surface 31 of each second tool 302 and the inner surface 15 of the casing 3.

The rotor 4 can further comprise a plurality of third tools 303 and/or a further plurality of tools 30 endowed with at least one cutting surface 31 ; the cutting surface 31 of each tool 30 can delimit, with the inner surface 15 of the casing 3, a respective radial gap. For example, between the cutting surfaces 31 of the plurality of third tools 303 and the inner surface 15 of the casing 3 a third radial gap 323 can be defined, as illustrated in figure 23. Preferably, the distance between the cutting surface 31 of each second tool 302 and the inner surface 15 of the casing 3 is greater than the distance between the cutting surface 31 of each third tool 303 and the inner surface 15 of the casing 3.

Preferably, the gap between the cutting surfaces 31 of the tools 30 and the inner surface 15 of the casing 3 is dimensionally decreased along the advancement path of the material inside the casing 3. For example, in accordance with this dimensionally decreasing trend of the radial gap along the advancement path of the material inside the casing 3, the third radial gap 323 can have a free passage section having a smaller area than the area of the free passage section of the second gap 322.

The inner surface 15 of the casing 3 can have a toothing 33 emerging transversally from the inner surface 15 of the casing 3 toward the cavity 9; preferably, the toothing 33 can extend perimetrally and/or circumferentially with respect to the cavity 9. The toothing 33 is composed of alternating recesses and teeth, which constitute the above-mentioned protuberances; each tooth can extend interposed between two recesses, emerging outwardly therefrom; the teeth are for example illustrated in figure 21. In particular, each tooth can emerge from the inner surface 15 of the casing 3, in particular outwardly from the recesses adjacent to the same tooth, for a depth J, which can be defined as the distance between the crest of the tooth (the crest of the tooth is defined in the portion of maximum radial extension of the tooth toward the cavity 9) and the surface of base of the adjacent recesses, as illustrated in figure 21. The teeth can further extend longitudinally along a direction that is substantially parallel to the main rotation axis A.

Preferably, the toothing 33 comprises a first and a second plurality of teeth 331 , 332; the second plurality 332 of teeth is arranged in series with respect to the first plurality 331 of teeth along the advancement path of the materials inside the casing 3. Each tooth of the first plurality 331 of teeth and of the second plurality 332 of teeth can emerge transversally from the inner surface 15 of the casing 3 respectively for a first depth J' and for a second depth J"; preferably, the second depth J" is less than the first depth J'. The toothing 33 can further comprise a third plurality of teeth 333 and/or further plurality of teeth, wherein the teeth of each plurality of teeth emerge transversally from the inner surface 15 of the casing 3 for a respective depth. In particular, the third plurality 333 of teeth can be arranged in series with respect to the second plurality 332 of teeth and the teeth thereof can emerge transversally from the inner surface of the casing for a third depth J'", which can be less than the second depth J" and/or than the first depth J'. Preferably, the depth of the teeth decreases along the advancement path of the material inside the casing 3, in particular at the third grinding stage 14.

From a dimensional view, the depths of the teeth can be on a millimetre scale; for example, the first depth J' can be in the range of between 5 and 10 mm, the second depth J" can be in the range of between 2 and 8 mm and the third depth J'" can be in the range of between 1 and 6 mm.

With reference to the reciprocal positioning between the toothing 33 emerging from the inner surface 15 of the casing 3 and the tools 30, the first plurality 331 of teeth can extend around the plurality of first tools 301 and the second plurality 332 of teeth can extend around the plurality of second tools 302. The toothing 33 can further comprise a third plurality 333 of teeth extending around the plurality of third tools 303. Preferably, each gap 32 is defined between a plurality of teeth emerging from the inner surface 15 of the casing 3 and the cutting surface 31 of the tools 30. Each gap 32 can further have a height H defined as the distance between the crest of the teeth of the toothing 33 and the cutting surface 31 of the tools 30, as illustrated in figure 21. In particular, the first gap 321 can have a first height H' defined between each tooth of the first plurality of teeth 331 in the point of the respective maximum radial dimension and the cutting surface 31 of the first tools 301 , as illustrated in figure 20. Analogously, the second gap 322 can have a second height H" defined between each tooth of the second plurality 332 of teeth in the point of the respective maximum radial dimension and the cutting surface 31 of the second tools 302, as illustrated in figure 22. In other words, the first height H' of the first gap 321 is defined between the crest of the teeth of the first plurality 331 of teeth and the cutting surface 31 of the first tools 301 ; analogously, the second height H" of the second gap 322 is defined between the crest of the teeth of the second plurality 332 of teeth and the cutting surface 31 of the second tools 302. Preferably, the second height H" is less than the first height H'. In particular, the height can decrease along the advancement path of the material inside the casing 3 across a further plurality of teeth arranged around a further plurality of tools 30. For example, the third gap 323 can have a third height H'" defined between each tooth of the third plurality 333 of teeth in the point of the respective maximum radial dimension and the cutting surface 31 of the third tools 303, as illustrated in figure 23. Preferably, the third height H'" is less than the second height H". From a dimensional viewpoint, the heights of the gaps can be on a millimetre scale; for example, the first height H' can be in the range of between 5 and 10 mm, the second height H" can be in the range of between 2 and 8 mm and the third height H'" can be in the range of between 1 and 6 mm.

With regard to the structure of the rotor 4, the tools 30 can be operatively associated with the shaft 24; preferably, the plurality of first tools 301 and the plurality of second tools 302 and/or further plurality of tools 30 rotate integrally with the shaft 24. With reference to the relative positioning between tools 30 and shaft 24 in a grinding stage, they can be connected by means of one or more discoidal elements 34 and a support structure 35. The rotor 4 can comprise one or more discoidal elements 34, in particular at least a first discoidal element 341 and a second discoidal element 342 and/or a third discoidal element 343, which can be directly keyed onto the shaft 24 so as to rotate integrally therewith. The rotor 4 can further comprise a support structure 35 for the first and second tools 301 , 302 and/or of the third tools 303 rotating integrally with the shaft 24. The support structure 35 can comprise at least a first circular crown 351 keyed onto a first discoidal element 341 and a second circular crown 352 keyed onto a second discoidal element 342 and/or a third circular crown 353 keyed onto a third discoidal element 343. The first circular crown 351 comprises a housing seat 36 for each tool 30 of the plurality of first tools 301 and the second circular crown 352 comprises a housing seat 36 for each tool 30 of the plurality of second tools 302; analogously, the third circular crown 353 comprises a housing seat 36 for each tool 30 of the plurality of third tools 303. Figure 18, for example, illustrates the housing seats 36 of the first circular crown 351 configured and intended to house the plurality of first tools 301. The rotor 4 can further comprise further discoidal elements 34 and/or further circular crowns, each of which can be keyed onto a respective discoidal element 34; for example, figure 12 illustrates a rotor 4 comprising a first, a second and a third circular crown 351 , 352, 353 keyed, respectively, onto a first, a second and a third discoidal element 341 , 342, 343 and in which a plurality of first, second and third tools 301 , 302, 303 are housed, respectively.

The circular crowns can comprise housing seats 36 for the tools 30; preferably, the tools 30 are mounted removably on the support structure 35 in the respective housing seats 36. The removable mounting of the tools 30 on the support structure 35 is particularly useful, for example, in order to facilitate the replacement thereof. The housing seats 36 of the tools 30 can consist in recesses fashioned in an outer portion of the circular crowns; in particular the recesses can have a substantially "U"-shaped profile. For example, the pluralities of first, second and third tools 301 , 302, 303 mounted in the respective housing seats 36 in an outer portion of the respective circular crowns are illustrated in figure 12.

The support structure 35 can further comprise supporting elements housed in the housing seats 36 of the tools 30; in particular, the tools 30 can be constrained, preferably removably, to the supporting elements in the respective housing seats 36.

The tools 30 can be further mounted in the respective housing seats 36 in an adjustable, in particular a radially adjustable, manner so as to modulate the radial dimension of the tools 30. The modulation of the radial dimension of the tools 30 can cause a consequent change in the height of one or more gaps 32, thus modifying the dimensions of the free passage section of one or more gaps 32; the adjustment of the radial position of the tools 30 can thus make it possible to control the particle size of the materials that can pass through the gaps 32 defined between the cutting surface 31 of the tools 30 and the inner surface 15 of the casing 3.

The tools 30 can be for example knives 252, a term which in the technical field of reference denotes tools endowed with one or more sharp profiles defining one or more cutting surfaces. In a step following the grinding of material inside the casing 3 at the first, second, third and/or further grinding stages, the material is conveyed out of the casing 3. In order to evacuate the ground material from the casing 3 itself under the normal operating conditions of the mill 1 , the mill 1 can be endowed with at least one evacuation conduit 50, which can be disposed downstream of the outlet section 11 for the exit of ground materials from the casing 3. In particular, the evacuation conduit 50 is operatively connected to the outlet section 11 of the casing 3; preferably, it is mounted on the outlet section 11 of the casing 3.

To facilitate and favour the evacuation of the materials, downstream of the outlet section 1 1 of the casing 3 the mill 1 can have suction means (not shown in the figures) configured to suck the materials out of the casing 3. In particular, the suction means are disposed downstream of the evacuation conduit 50 and are operatively connected to the outlet section 11 for the exit of the materials from the casing 3 by means of the evacuation conduit 50 itself. In other words, the suction means facilitate the evacuation of the material by generating a negative pressure capable of moving the ground material toward an outlet section of the evacuation conduit 50. The suction means can comprise, for example, at least one cyclone separator (not shown in the figures). Preferably, the suction means can be configured to process the ground metal materials and/or other materials and/or phases such as paints or other volatile phases; therefore, downstream of the suction means there can be placed at least one filtering element configured to separate the different materials sucked out and/or the different phases present in the materials exiting the casing 3. The filtering element can comprise a filter configured to separate dust from gases, preferably the filter can be of the "baghouse" type.

The mill 1 can be further endowed with a door 55 for evacuating the non-grindable materials from the casing 3; the door 55 can be set in a lower portion 20 of the casing 3 below the rotor 4, as illustrated in figure 25, and is configured to rotate at least partially with respect to a lower portion 20 of the casing 3 between at least one closed position and at least one open position. Under normal operating conditions of the mill 1 , the door 55 is in the closed position, whereas in the event of anomalous operating conditions of the mill 1 the door can be moved so as to assume the open position; the open position of the door 55 is shown in figure 25. An example of such anomalous conditions consists in the jamming of the rotor 4, which may be due, for example, to the presence of materials of an excessively large size which the rotor 4 is unable to process or to discharge via the evacuation conduit 50; under such conditions the door 55 can be opened in order to evacuate the material from the inside of the casing 3.

The present invention further relates to a process for grinding metal materials comprising at least the steps of: providing a mill for grinding metal materials, feeding metal material to be ground into the inlet section of the casing and actuating the rotor in rotation so as to grind the metal material. Preferably, the mill designed to implement said process can be a mill 1 of the previously described type. In particular, the step of loading the metal material can comprise a step of forcing the material to enter the casing 3 in an inlet section 10; this step can be carried out by means of a pusher 8, for example of a hydraulic type.

The process can further comprise one or more of the following steps:

grinding the material at the first grinding stage 12;

enabling a passage, through the plurality of openings 220 of the first separating wall 22, of a fraction of ground material having a particle size equal to or smaller than a first particle size, the first particle size being correlated to a passage area of the openings 220 of the first separating wall 22;

further grinding the material at the second grinding stage 13 at least in a second particle size.

The process can further comprise the step of enabling a passage, through the plurality of openings 230 of the second separating wall 23, of a fraction of ground material having a particle size equal to or smaller than the second particle size. The process can comprise further one or more of the following steps:

grinding the metal material in the first gap 321 ;

grinding the metal material in the second gap 322;

grinding the metal material in the third gap 323.

The process can comprise further the step of evacuating ground material from the outlet section 11 ; the evacuation step can comprise a suction step carried out by the suction means.

The present invention makes it possible to obtain one or more of the following advantages and to resolve one or more of the problems encountered in the prior art. The invention makes it possible to optimize the process of grinding metal materials inside the mill. The present invention further makes it possible to facilitate the evacuation of ground materials from the casing.

The invention is moreover convenient to use, easy to implement and simple and economical to construct.

Claims

A mill (1) for grinding materials comprising:

a casing (3) comprising an inlet section (10) and an outlet section (11) for the materials from the casing (3), the casing (3) defining an inner cavity (9) and delimiting an advancement path for the materials from the inlet section (10) to the outlet section (11) of the casing (3) through the inner cavity (9);

at least one rotor (4) arranged inside the cavity (9) and configured for rotating with respect to the casing (3), the rotor (4) comprising a shaft (24) engaged to the casing (3) for rotation around a main axis (A) and a plurality of grinding elements (25) associated to the shaft (24),

said mill (1) including at least a first and a second grinding stage (12; 13), the second grinding stage (13) being arranged in series with respect to the first grinding stage (12) along the advancement path for the materials inside the casing (3), the casing further comprising at least one separating wall (22) developing transversally with respect to an inner surface (15) of the casing, the separating wall (22) being interposed between the first and the second grinding stage (12; 13) and having a plurality of openings (220) for a selective passage of the material from the first grinding stage (12) to the second grinding stage (13).

The mill (1) according to claim 1 , wherein the separating wall (22) projects from the inner surface (15) of the casing (3) towards the cavity (9) and/or develops perimetrally with respect to the cavity (9) and/or wherein the cavity (9) is substantially cylindrical and the separating wall (22) develops circumferentially with respect to the cavity (9), defining a wall shaped as a circular crown projecting from the inner surface (15) of the casing (3) in a substantially perpendicular direction thereto.

The mill (1) according to claim 1 or 2, wherein the mill (1) comprises connecting parts (26) between the grinding elements (25) and the shaft (24) and/or wherein the connecting parts (26) comprise a plurality of discs (27) mounted to the shaft (24) so as to be at least rotationally connected to the shaft (24) itself and/or wherein the plurality of discs (27) comprises one or more pairs of adjacent discs (27), each pair of discs (27) carrying one or more grinding elements (25) which develop at least partially at a gap defined between mutually facing faces of the discs (27) of said pair of discs (27) and/or wherein each pair of discs (27) has at least a first pair (291) of homologous through- holes (29) comprising a first hole (298) and a second hole (299), the first hole (298) being defined at a first disc (278) of said pair of discs (27), the second hole (299) being defined at a second disc (279) of said pair of discs (27), the first and the second hole (298; 299) being aligned along a secondary axis substantially parallel to the main axis (A) of rotation of the shaft (24) and spaced away from the main axis (A), the first and the second disc (278; 279) being connected to each other by at least one respective pin (28) passing through the pair of discs (27) at the first hole (298) and at the second hole (299), the respective pin (28) developing transversally with respect to the mutually facing faces of the discs (27) of the pair of discs (27) along the secondary axis.

The mill (1) according to the preceding claim, wherein the first grinding stage (12) comprises at least a first pair (271) of discs (27) and the second grinding stage (13) comprises at least a first respective pair of discs (27), each pair of discs (27) carrying at least two grinding elements (25).

The mill (1) according to any one of the preceding claims, wherein the grinding elements (25) at the first and/or at the second grinding stage (12; 13) comprise at least one selected in the group including: a plurality of grinding elements (25) having a star- shaped profile, a plurality of grinding elements (25) having a hammer-shaped profile and a plurality of grinding elements (25) having a profile characterized by at least one cutting surface.

The mill (1) according to any one of the preceding claims, wherein said at least one separating wall (22) comprises a first and a second separating wall (22; 23), the first separating wall (22) developing between the first and the second grinding stage (12; 13), the second separating wall (23) developing at an outlet portion for the materials from the second grinding stage (13), the first separating wall (22) having a plurality of openings (220) for the passage of the material from the first grinding stage (12) to the second grinding stage (13), and the second separating wall (23) having a respective plurality of openings (230) for letting the material out of the second grinding stage (13). The mill (1) according to any one of the preceding claims, wherein the mill (1) further comprises a third grinding stage (14) arranged in series with respect to the second grinding stage (13) along the advancement path for the materials inside the casing (3), and wherein the rotor (4) further comprises:

a plurality of first tools (301) operatively associated to the shaft (24) at the third grinding stage (14), each one of said first tools (301) having at least one cutting surface (31) facing an inner surface (15) of the casing (3),

a plurality of second tools (302) operatively associated to the shaft (24) at the third grinding stage (14) in series with respect to the first tools (301), each one of said second tools (302) having at least one cutting surface (31) facing an inner surface (15) of the casing (3),

wherein the cutting surface (31) of the first tools (301) delimits with the inner surface (15) of the casing (3) a first radial gap (321), wherein the cutting surface (31) of the second tools (302) delimits with the inner surface (15) of the casing (3) a second radial gap (322) placed downstream from the first gap (321), and wherein the first gap (321) has a free passage section having a greater area than the area of the free passage section of the second gap (322).

8. The mill (1) according to the preceding claim, wherein the rotor (4) comprises a plurality of third tools (303) and/or further pluralities of tools (30), the tools (30) having at least one cutting surface (31) facing an inner surface (15) of the casing (3), the cutting surface (31) of the tools (30) of each plurality of tools (30) delimiting with the inner surface (15) of the casing (3) a respective radial gap (32) and/or wherein the gap (32) between the cutting surfaces (31) of the tools (30) and the inner surface (15) of the casing (3) gets thinner along the advancement path for the materials inside the casing (3).

9. The mill (1) according to any one of the preceding claims, wherein the mill (1) comprises suction means for the materials working downstream from the outlet section (11) of the casing (3), the suction means being operatively connected to the outlet section (11) for the materials from the casing (3) and being configured for sucking the materials out of the casing (3) and/or wherein the suction means comprise a cyclone separator.

10. A process for grinding metal materials comprising steps of:

providing a mill (1) according to any one of the preceding claims;

feeding metal material to be ground at the inlet section (10) of the casing (3); actuating said rotor (4) in rotation so as to grind the metal material.